Q.1 Which surface modification technique uses ionized gas to introduce functional groups onto a biomaterial surface?
Electrospinning
Plasma treatment
Sol‑gel coating
Layer‑by‑layer assembly
Explanation - Plasma treatment generates a reactive plasma that can graft functional groups (e.g., –OH, –COOH) onto material surfaces without affecting bulk properties.
Correct answer is: Plasma treatment
Q.2 What is the primary purpose of graft polymerization on a biomaterial surface?
To increase bulk mechanical strength
To create a conductive core
To attach bioactive molecules while preserving bulk properties
To reduce material density
Explanation - Graft polymerization forms polymer chains covalently bonded to the surface, allowing functionalization (e.g., cell‑adhesive ligands) without altering the interior of the material.
Correct answer is: To attach bioactive molecules while preserving bulk properties
Q.3 Which of the following is a common result of increasing surface roughness on an implant material?
Decreased electrical conductivity
Enhanced osteointegration
Reduced corrosion resistance
Lower tensile strength
Explanation - Micron‑scale roughness provides more surface area and mechanical interlocking for bone cells, promoting better integration of the implant.
Correct answer is: Enhanced osteointegration
Q.4 Self‑assembled monolayers (SAMs) are used to modify biomaterial surfaces primarily because they:
Create thick protective coatings
Form highly ordered, single‑molecule thick layers
Increase bulk conductivity
Introduce bulk porosity
Explanation - SAMs consist of molecules that spontaneously organize into a well‑defined monolayer, allowing precise control over surface chemistry.
Correct answer is: Form highly ordered, single‑molecule thick layers
Q.5 In layer‑by‑layer (LbL) assembly, the driving force for film growth is:
Covalent bonding between layers
Electrostatic attraction between oppositely charged polyelectrolytes
Thermal diffusion
Magnetic alignment
Explanation - LbL builds up multilayers by alternating adsorption of positively and negatively charged polymers, relying on electrostatic forces.
Correct answer is: Electrostatic attraction between oppositely charged polyelectrolytes
Q.6 Which surface modification method is most suitable for creating a conductive polymer coating on a metallic implant?
Silane coupling
Electrochemical polymerization
Physical vapor deposition
Laser ablation
Explanation - Electrochemical polymerization deposits conductive polymers (e.g., polypyrrole) directly onto conductive substrates, allowing control over thickness and conductivity.
Correct answer is: Electrochemical polymerization
Q.7 The term "bio‑inert" when describing a surface modification means:
The surface actively promotes cell adhesion
The surface resists protein adsorption and cell attachment
The surface conducts electricity
The surface degrades rapidly in vivo
Explanation - Bio‑inert surfaces aim to minimize biological interactions, reducing unwanted fouling or immune response.
Correct answer is: The surface resists protein adsorption and cell attachment
Q.8 Which analytical technique is commonly used to verify the chemical composition of a modified biomaterial surface?
Scanning electron microscopy (SEM)
X‑ray photoelectron spectroscopy (XPS)
Dynamic mechanical analysis (DMA)
Fourier‑transform infrared spectroscopy (FTIR)
Explanation - XPS provides elemental composition and chemical state information of the top few nanometers of a surface, ideal for confirming modifications.
Correct answer is: X‑ray photoelectron spectroscopy (XPS)
Q.9 A common reason to apply a hydroxyapatite coating to a titanium orthopedic implant is to:
Increase electrical conductivity
Improve radiopacity
Enhance bone bonding
Reduce manufacturing cost
Explanation - Hydroxyapatite mimics bone mineral, promoting osteoconduction and stronger bonding between bone and implant.
Correct answer is: Enhance bone bonding
Q.10 Which of the following modifications would most likely reduce bacterial adhesion on a catheter surface?
Increasing surface hydrophobicity
Applying a zwitterionic polymer coating
Roughening the surface
Adding a positively charged layer
Explanation - Zwitterionic polymers resist protein and bacterial adhesion due to their charge neutrality and strong hydration layer.
Correct answer is: Applying a zwitterionic polymer coating
Q.11 In the context of surface modification, the term "functionalization" most accurately refers to:
Changing the bulk crystal structure
Adding specific chemical groups that confer desired surface properties
Increasing the overall mass of the material
Removing surface contaminants
Explanation - Functionalization introduces moieties such as –NH₂, –COOH, or bioactive peptides that tailor interactions with cells or proteins.
Correct answer is: Adding specific chemical groups that confer desired surface properties
Q.12 Which surface modification method typically requires a high‑vacuum environment?
Plasma polymerization
Chemical vapor deposition (CVD)
Dip coating
UV‑ozone treatment
Explanation - CVD processes are performed under low pressure to allow vapor‑phase precursors to react and deposit thin films on the substrate.
Correct answer is: Chemical vapor deposition (CVD)
Q.13 A common metric to assess the wettability of a modified biomaterial surface is:
Young’s modulus
Contact angle
Electrical resistivity
Hardness
Explanation - The static water contact angle indicates how hydrophilic or hydrophobic a surface is; lower angles mean higher wettability.
Correct answer is: Contact angle
Q.14 Which surface modification technique can be used to immobilize growth factors on a polymer scaffold without compromising their bioactivity?
Thermal annealing
Physical adsorption at high temperature
Covalent coupling via carbodiimide chemistry
Ion implantation
Explanation - Carbodiimide (EDC/NHS) chemistry links carboxyl groups on the surface to amine groups on proteins, preserving activity under mild conditions.
Correct answer is: Covalent coupling via carbodiimide chemistry
Q.15 What is the main advantage of using nanostructured surface topographies in cardiovascular stents?
Reduced electrical resistance
Enhanced endothelialization and reduced restenosis
Increased stent rigidity
Improved radiopacity
Explanation - Nanotopographies promote endothelial cell adhesion while limiting smooth‑muscle cell proliferation, lowering the risk of restenosis.
Correct answer is: Enhanced endothelialization and reduced restenosis
Q.16 Silane coupling agents are primarily used to:
Create a metallic bond between two metals
Link organic molecules to inorganic surfaces such as glass or silicon
Increase thermal conductivity
Reduce surface charge
Explanation - Silane molecules have bifunctional groups; one reacts with the inorganic substrate while the other provides a reactive site for organic chemistry.
Correct answer is: Link organic molecules to inorganic surfaces such as glass or silicon
Q.17 Which surface modification approach can be applied to create a gradient of bioactive ligand density across a biomaterial?
Uniform dip‑coating
Mask‑less photolithography
Spin coating
Thermal oxidation
Explanation - By varying exposure dose, photolithography can pattern surfaces with a continuous gradient of functional groups or ligands.
Correct answer is: Mask‑less photolithography
Q.18 The term "bioactive" surface modification refers to:
A surface that passively resists all biological interactions
A surface that actively promotes specific cellular responses
A surface that degrades in seconds
A surface that conducts electricity
Explanation - Bioactive modifications are designed to interact with cells or tissues, such as encouraging osteogenesis or endothelialization.
Correct answer is: A surface that actively promotes specific cellular responses
Q.19 Which of the following is NOT a typical outcome of plasma surface treatment on polymers?
Increased surface energy
Cross‑linking of bulk polymer chains
Introduction of polar functional groups
Improved adhesion of coatings
Explanation - Plasma mainly affects the top nanometers, altering chemistry and energy without significantly cross‑linking the bulk material.
Correct answer is: Cross‑linking of bulk polymer chains
Q.20 Electrospun nanofibrous scaffolds can be surface‑modified to improve cell attachment by:
Increasing fiber diameter to >500 µm
Coating with extracellular matrix proteins like fibronectin
Heating to melt fibers
Adding metallic particles
Explanation - Protein coatings provide natural adhesion motifs (e.g., RGD) that enhance cell attachment on nanofibrous substrates.
Correct answer is: Coating with extracellular matrix proteins like fibronectin
Q.21 Which technique would you use to deposit a thin, conformal oxide layer on a curved biomedical implant?
Atomic layer deposition (ALD)
Sputtering
Melt extrusion
Laser cutting
Explanation - ALD provides atomic‑scale control and uniform coverage on complex geometries, ideal for thin oxide films on implants.
Correct answer is: Atomic layer deposition (ALD)
Q.22 A surface that exhibits a water contact angle of 10° is considered:
Hydrophobic
Superhydrophobic
Hydrophilic
Superhydrophilic
Explanation - Contact angles <20° indicate superhydrophilicity, meaning the surface strongly attracts water.
Correct answer is: Superhydrophilic
Q.23 Ion implantation as a surface modification method primarily changes:
Surface chemistry via implanted ions
Bulk mechanical strength
Overall material density
Color of the material
Explanation - Ion implantation embeds energetic ions into the near‑surface region, altering chemical composition and properties without removing material.
Correct answer is: Surface chemistry via implanted ions
Q.24 Which of the following surface modifications can improve the hemocompatibility of a vascular graft?
Applying a hydrophobic fluoropolymer coating
Grafting heparin onto the surface
Roughening the surface with sandblasting
Depositing a thick metal layer
Explanation - Heparin is an anticoagulant; covalently grafting it reduces platelet adhesion and clot formation on blood-contacting devices.
Correct answer is: Grafting heparin onto the surface
Q.25 The main benefit of using a gradient surface stiffness in a biomaterial scaffold is:
Uniform cell distribution
Mimicking tissue interfaces that transition from soft to stiff
Increasing overall scaffold weight
Reducing electrical resistance
Explanation - Gradients in stiffness can replicate natural tissue transitions (e.g., cartilage‑bone), guiding cell differentiation and tissue formation.
Correct answer is: Mimicking tissue interfaces that transition from soft to stiff
Q.26 Which of these is a common method for attaching antibodies to a biomaterial surface for biosensing applications?
Physical adsorption at high temperature
Covalent bonding via maleimide-thiol chemistry
Embedding the antibodies in bulk polymer matrix
Ion implantation
Explanation - Maleimide groups react specifically with thiol groups on antibodies, forming stable covalent links while preserving antigen‑binding sites.
Correct answer is: Covalent bonding via maleimide-thiol chemistry
Q.27 When a titanium implant is anodized, the primary surface change is:
Formation of a thick polymer coating
Creation of a nanostructured TiO₂ oxide layer
Embedding of metallic particles
Reduction of surface roughness
Explanation - Anodization grows a controlled TiO₂ layer with nano‑features that improve osseointegration and corrosion resistance.
Correct answer is: Creation of a nanostructured TiO₂ oxide layer
Q.28 Which surface modification approach can render a normally bio‑active polymer surface bio‑inert?
Grafting polyethylene glycol (PEG) chains
Plasma etching
Thermal annealing
Embedding silver nanoparticles
Explanation - PEG creates a hydrated, protein‑resistant brush that prevents cell adhesion, making the surface bio‑inert.
Correct answer is: Grafting polyethylene glycol (PEG) chains
Q.29 A common way to assess protein adsorption on a modified biomaterial surface is:
Tensile testing
BCA (bicinchoninic acid) assay
Differential scanning calorimetry
X‑ray diffraction
Explanation - The BCA assay quantifies protein concentration on a surface by measuring colorimetric change after protein extraction.
Correct answer is: BCA (bicinchoninic acid) assay
Q.30 Which of the following modifications would most likely increase the electrical conductivity of a polymer scaffold for neural tissue engineering?
Coating with gold nanoparticles
Embedding silica particles
Adding a hydrophobic fluoropolymer layer
Surface roughening with sandblasting
Explanation - Gold nanoparticles provide conductive pathways, enhancing overall scaffold conductivity without compromising flexibility.
Correct answer is: Coating with gold nanoparticles
Q.31 In biomaterials, the term "osteoconductive" refers to a surface that:
Prevents bone growth
Promotes bone cell adhesion and growth along its surface
Conducts electrical signals in bone
Degrades within a week
Explanation - Osteoconductive materials act as a scaffold for new bone tissue to grow onto and integrate with.
Correct answer is: Promotes bone cell adhesion and growth along its surface
Q.32 What is the main purpose of using a "click chemistry" reaction (e.g., azide‑alkyne cycloaddition) on biomaterial surfaces?
To increase surface roughness
To enable highly specific, rapid, and bio‑orthogonal coupling of functional molecules
To remove surface contaminants
To melt the polymer surface
Explanation - Click chemistry provides a clean, fast reaction that proceeds under mild conditions, ideal for attaching biomolecules to surfaces.
Correct answer is: To enable highly specific, rapid, and bio‑orthogonal coupling of functional molecules
Q.33 Which surface treatment would you apply to a silicone catheter to reduce protein fouling?
Silane‑based fluorination
Plasma polymerization of PEG‑like monomers
Thermal oxidation at 500 °C
Embedding carbon fibers
Explanation - PEG-like plasma polymers create a hydrophilic, protein‑resistant surface that diminishes fouling on silicone.
Correct answer is: Plasma polymerization of PEG‑like monomers
Q.34 The use of a nanometer‑scale titanium dioxide (TiO₂) coating on a dental implant primarily serves to:
Increase the implant's radiopacity
Provide photocatalytic antibacterial activity under UV light
Reduce the elastic modulus
Make the implant magnetic
Explanation - TiO₂ can generate reactive oxygen species when illuminated, killing bacteria and reducing infection risk.
Correct answer is: Provide photocatalytic antibacterial activity under UV light
Q.35 Which surface modification method is best suited for creating a patterned array of cell‑adhesive islands on a polymer film?
Spin coating
Microcontact printing
Bulk melt extrusion
Thermal annealing
Explanation - Microcontact printing uses a stamp to transfer inked biomolecules onto defined regions, producing patterned adhesive islands.
Correct answer is: Microcontact printing
Q.36 A surface that exhibits a water contact angle of 110° is considered:
Superhydrophilic
Hydrophilic
Hydrophobic
Superhydrophobic
Explanation - Contact angles between 90° and 150° indicate hydrophobic surfaces; >150° would be superhydrophobic.
Correct answer is: Hydrophobic
Q.37 Which modification technique can be used to introduce a gradient of stiffness in a hydrogel scaffold?
Uniform UV cross‑linking
Photopolymerization with a spatial light modulator
Bulk freeze‑drying
Thermal curing in an oven
Explanation - By varying light intensity across the hydrogel, cross‑link density—and thus stiffness—can be spatially controlled.
Correct answer is: Photopolymerization with a spatial light modulator
Q.38 In the context of biomaterial surfaces, the term "zwitterionic" refers to:
A surface bearing only positive charges
A surface bearing both positive and negative charges in the same molecule
A surface that is electrically conductive
A surface that degrades in water
Explanation - Zwitterionic groups contain both cationic and anionic sites, creating strong hydration shells that resist fouling.
Correct answer is: A surface bearing both positive and negative charges in the same molecule
Q.39 Which analytical method would you choose to measure nanoscale surface topography after a modification step?
Atomic force microscopy (AFM)
Thermogravimetric analysis (TGA)
Differential scanning calorimetry (DSC)
Fourier‑transform infrared spectroscopy (FTIR)
Explanation - AFM provides high‑resolution topographical maps of surfaces down to sub‑nanometer height differences.
Correct answer is: Atomic force microscopy (AFM)
Q.40 The primary effect of grafting a RGD peptide onto a polymer surface is to:
Increase the surface hardness
Promote specific integrin‑mediated cell adhesion
Make the surface electrically conductive
Create a magnetic surface
Explanation - RGD is a cell‑binding motif recognized by integrin receptors, enhancing adhesion of many cell types.
Correct answer is: Promote specific integrin‑mediated cell adhesion
Q.41 Which surface modification method can be performed at room temperature and is compatible with temperature‑sensitive biomolecules?
Thermal oxidation
Plasma polymerization with low‑power RF
Electron beam lithography
Hot‑press molding
Explanation - Low‑power plasma can graft functional groups without raising bulk temperature, preserving delicate biomolecules.
Correct answer is: Plasma polymerization with low‑power RF
Q.42 When a surface is modified with a dense layer of PEG, the main observed change in cell culture is:
Increased cell proliferation
Reduced cell attachment and spreading
Enhanced cell differentiation
Higher electrical conductivity
Explanation - PEG creates a steric barrier that prevents proteins and cells from adhering to the surface.
Correct answer is: Reduced cell attachment and spreading
Q.43 A surface that releases nitric oxide (NO) upon contact with blood is intended to:
Increase platelet activation
Promote vasodilation and inhibit platelet adhesion
Accelerate corrosion
Increase electrical resistance
Explanation - NO is a natural vasodilator and antithrombotic agent; its release improves hemocompatibility of blood‑contacting devices.
Correct answer is: Promote vasodilation and inhibit platelet adhesion
Q.44 Which surface modification technique can be used to create a nano‑patterned array of pits on a metallic implant without using masks?
Laser interference lithography
Mechanical polishing
Electroplating
Thermal annealing
Explanation - Interference of coherent laser beams generates periodic intensity patterns that can directly ablate or modify surfaces at the nanoscale.
Correct answer is: Laser interference lithography
Q.45 The term "bio‑resorbable" when describing a surface coating means that the coating:
Remains permanently on the device
Gradually degrades into non‑toxic by‑products in the body
Conducts electricity
Becomes magnetic over time
Explanation - Bio‑resorbable coatings are designed to disappear safely after serving their function, eliminating the need for removal surgery.
Correct answer is: Gradually degrades into non‑toxic by‑products in the body
Q.46 A common method to functionalize the surface of a glass slide for DNA microarray fabrication is:
Sputter deposition of gold
Silane‑based amino‑functionalization
Thermal oxidation
Ion implantation of nitrogen
Explanation - Aminosilanes (e.g., APTES) provide reactive –NH₂ groups that can covalently bind DNA probes onto glass surfaces.
Correct answer is: Silane‑based amino‑functionalization
Q.47 Which of the following surface modifications can improve the wear resistance of a polymer joint component?
Grafting of soft hydrogel layers
Coating with diamond‑like carbon (DLC) film
Embedding of low‑density foams
Increasing surface hydrophobicity
Explanation - DLC provides a hard, low‑friction coating that markedly enhances wear resistance of polymeric components.
Correct answer is: Coating with diamond‑like carbon (DLC) film
Q.48 When evaluating the success of a surface‑modified orthopedic implant, which in‑vivo metric is most directly related to surface chemistry?
Pull‑out strength
Blood glucose level
Radiographic bone density around the implant
Patient’s body temperature
Explanation - Pull‑out tests measure the mechanical fixation of the implant, which is strongly influenced by surface chemistry that promotes bone bonding.
Correct answer is: Pull‑out strength
Q.49 What is the main advantage of using a “click‑type” azide‑alkyne reaction over traditional carbodiimide chemistry for surface functionalization?
It requires higher temperatures
It is faster, more specific, and works in aqueous environments without side‑reactions
It creates a metallic bond
It reduces surface roughness
Explanation - Click chemistry proceeds under mild, bio‑compatible conditions and yields quantitative coupling with minimal by‑products.
Correct answer is: It is faster, more specific, and works in aqueous environments without side‑reactions
Q.50 A surface that is modified with a layer of chitosan primarily aims to:
Increase electrical conductivity
Provide antibacterial activity and improve biocompatibility
Make the surface magnetic
Decrease surface hardness
Explanation - Chitosan is a natural polysaccharide with inherent antimicrobial properties and good cell compatibility.
Correct answer is: Provide antibacterial activity and improve biocompatibility
Q.51 Which of the following would most likely increase the surface energy of a polymer?
Coating with a fluorinated polymer
Plasma oxidation to introduce –OH groups
Embedding hydrophobic silica particles
Applying a thick silicone oil layer
Explanation - Introducing polar –OH groups raises surface energy, making the surface more wettable.
Correct answer is: Plasma oxidation to introduce –OH groups
Q.52 A biomaterial surface that releases silver ions is mainly intended to:
Enhance osteogenesis
Provide antibacterial activity
Increase electrical conductivity
Promote angiogenesis
Explanation - Silver ions disrupt bacterial cell membranes and metabolic pathways, offering a broad‑spectrum antimicrobial effect.
Correct answer is: Provide antibacterial activity
Q.53 Which technique can simultaneously modify surface chemistry and create micro‑scale topographical features in a single step?
Spin coating
Laser‑induced periodic surface structuring (LIPSS)
Hot‑press molding
Bulk extrusion
Explanation - LIPSS uses interference of laser light to create periodic nano‑/micro‑structures while also altering chemistry via photon‑induced reactions.
Correct answer is: Laser‑induced periodic surface structuring (LIPSS)
Q.54 When a polymer surface is treated with UV‑ozone, the main chemical change is:
Formation of carbon‑carbon double bonds
Oxidation leading to carbonyl and hydroxyl groups
Deposition of metal particles
Reduction of surface charge
Explanation - UV‑ozone generates reactive oxygen species that oxidize the polymer surface, introducing polar groups.
Correct answer is: Oxidation leading to carbonyl and hydroxyl groups
Q.55 Which surface modification approach is most suitable for creating a biodegradable polymer coating that releases a drug over weeks?
Physical vapor deposition of metal
Electrospinning of drug‑loaded nanofibers onto the surface
Laser ablation
Ion implantation
Explanation - Electrospun fibers can encapsulate drugs and degrade gradually, providing controlled release from a polymeric coating.
Correct answer is: Electrospinning of drug‑loaded nanofibers onto the surface
Q.56 What is the primary reason for using a “passivation layer” on a stainless‑steel stent?
To increase electrical conductivity
To prevent corrosion and reduce ion release
To make the stent magnetic
To lower the elastic modulus
Explanation - Passivation creates a thin, stable oxide film that protects the metal from aggressive bodily fluids.
Correct answer is: To prevent corrosion and reduce ion release
Q.57 A surface modified with a high density of carboxyl (–COOH) groups is expected to:
Be highly hydrophobic
Bind positively charged biomolecules through electrostatic attraction
Become magnetic
Increase thermal conductivity
Explanation - Carboxyl groups are negatively charged at physiological pH and attract positively charged species like certain proteins or peptides.
Correct answer is: Bind positively charged biomolecules through electrostatic attraction
Q.58 Which surface modification method can be used to create a thin, uniform polymer brush layer on a glass substrate?
Grafting‑to approach using pre‑synthesized polymers
Bulk melt extrusion
Thermal annealing
Sandblasting
Explanation - The grafting‑to method attaches pre‑made polymer chains bearing reactive end groups to a functionalized surface, forming dense brushes.
Correct answer is: Grafting‑to approach using pre‑synthesized polymers
Q.59 Which of the following is a characteristic of a “superhydrophobic” surface?
Water contact angle >150° and low sliding angle
Water contact angle <20°
Complete absorption of water
Uniform water spreading
Explanation - Superhydrophobicity combines high contact angle with low adhesion, causing water droplets to roll off easily.
Correct answer is: Water contact angle >150° and low sliding angle
Q.60 To improve the integration of a neural electrode with brain tissue, a surface modification should aim to:
Increase stiffness dramatically
Introduce anti‑inflammatory and neurotrophic factors
Make the surface highly hydrophobic
Add a thick metal layer
Explanation - Modifying the electrode surface with anti‑inflammatory agents and neurotrophic cues reduces glial scarring and promotes neuronal attachment.
Correct answer is: Introduce anti‑inflammatory and neurotrophic factors
Q.61 When a titanium surface is functionalized with phosphonic acid groups, the primary benefit is:
Improved corrosion resistance
Strong covalent bonding to TiO₂ for stable coating attachment
Increased electrical resistivity
Reduced biocompatibility
Explanation - Phosphonic acids form robust P‑O‑Ti bonds with titanium oxide, ensuring durable attachment of subsequent layers.
Correct answer is: Strong covalent bonding to TiO₂ for stable coating attachment
Q.62 A biomaterial surface that is engineered to release growth factors in a temporally controlled manner typically uses:
Rapidly degrading PEG hydrogels
Layer‑by‑layer (LbL) multilayers with degradable polyelectrolytes
Permanent metal coatings
Silicone rubber layers
Explanation - LbL allows precise stacking of layers that can be programmed to degrade and release embedded growth factors over time.
Correct answer is: Layer‑by‑layer (LbL) multilayers with degradable polyelectrolytes
Q.63 Which technique would you use to quantify the thickness of a nanometer‑scale coating on a biomaterial?
Scanning electron microscopy (SEM)
Ellipsometry
Tensile testing
Differential scanning calorimetry (DSC)
Explanation - Ellipsometry measures changes in polarized light reflected from thin films, providing accurate thickness data for sub‑nanometer layers.
Correct answer is: Ellipsometry
Q.64 A surface coating that is both conductive and biodegradable is most suitable for:
Permanent orthopedic implants
Transient neural interfaces that dissolve after use
Dental crowns
Heart valve leaflets
Explanation - Such coatings enable temporary electrical stimulation while safely resorbing, eliminating the need for surgical removal.
Correct answer is: Transient neural interfaces that dissolve after use
Q.65 Which surface modification approach is commonly employed to improve the adhesion of polymeric films on metal substrates?
Sputter deposition of a thin adhesion promoter layer (e.g., chromium)
Thermal annealing at 800 °C
Laser ablation of the polymer
Embedding polymer particles in metal
Explanation - Chromium forms strong bonds with both metal and polymer, enhancing interfacial adhesion.
Correct answer is: Sputter deposition of a thin adhesion promoter layer (e.g., chromium)
Q.66 When a biomaterial surface is functionalized with a catechol (dopamine‑derived) coating, the expected benefit is:
Increased hydrophobicity
Strong universal adhesion to diverse substrates
Reduced electrical conductivity
Increased surface roughness only
Explanation - Catechol groups mimic mussel adhesive proteins, binding to metals, oxides, polymers, and ceramics through multiple interactions.
Correct answer is: Strong universal adhesion to diverse substrates
Q.67 A major limitation of bulk surface modification methods (e.g., melt blending) compared with true surface‑specific techniques is:
Inability to change bulk mechanical properties
Potential alteration of the material’s bulk properties
Requirement for high‑vacuum environments
Only works on metallic substrates
Explanation - Bulk methods affect the entire material, possibly compromising strength, flexibility, or other bulk characteristics.
Correct answer is: Potential alteration of the material’s bulk properties
Q.68 Which of the following surface modifications would most likely enhance the hemocompatibility of a polymeric heart valve leaflets?
Grafting a dense PEG brush layer
Applying a thick silicone coating
Roughening the surface with sandblasting
Embedding iron particles
Explanation - PEG brushes create a hydrated, protein‑repellent surface that reduces platelet adhesion and thrombus formation.
Correct answer is: Grafting a dense PEG brush layer
Q.69 Which method can be used to create a surface that switches between hydrophilic and hydrophobic states in response to pH changes?
Coating with a pH‑responsive polymer such as poly(2‑dimethylamino)ethyl methacrylate (PDMAEMA)
Applying a permanent fluoropolymer coating
Thermal annealing
Ion implantation of inert gases
Explanation - PDMAEMA protonates/deprotonates with pH, changing its hydrophilicity and thereby the surface wettability.
Correct answer is: Coating with a pH‑responsive polymer such as poly(2‑dimethylamino)ethyl methacrylate (PDMAEMA)
Q.70 When a surface is treated with ozone, which functional group is most likely introduced onto a polymer?
Methyl (–CH₃)
Carbonyl (C=O) and carboxyl (–COOH)
Silane (–Si–)
Amide (–CONH₂)
Explanation - Ozone is a strong oxidant that forms carbonyl and carboxyl groups on polymer surfaces, increasing polarity.
Correct answer is: Carbonyl (C=O) and carboxyl (–COOH)
Q.71 A surface-modified polymer intended for cartilage repair should possess which mechanical characteristic?
High stiffness comparable to bone
Low elastic modulus similar to native cartilage
Magnetic properties
Electrical conductivity
Explanation - Matching the mechanical compliance of cartilage helps distribute loads and promotes proper tissue function.
Correct answer is: Low elastic modulus similar to native cartilage
Q.72 Which surface modification technique can be performed in a liquid environment and is therefore suitable for delicate biomolecules?
Plasma etching
Click chemistry (azide‑alkyne cycloaddition) in aqueous media
Sputter coating
Electron beam lithography
Explanation - The copper‑catalyzed click reaction proceeds efficiently in water at room temperature, preserving biomolecule activity.
Correct answer is: Click chemistry (azide‑alkyne cycloaddition) in aqueous media
Q.73 What is the primary reason for using a “nanotopographical” surface on a dental implant?
To reduce the implant’s color contrast
To increase the surface area for bone cell attachment and accelerate osseointegration
To make the implant electrically conductive
To lower the manufacturing cost
Explanation - Nanotopography mimics natural bone structure, fostering faster and stronger bone integration.
Correct answer is: To increase the surface area for bone cell attachment and accelerate osseointegration
Q.74 Which surface modification would be most appropriate to make a polymeric scaffold resistant to enzymatic degradation in vivo?
Grafting with a hydrophilic PEG brush
Coating with a thin layer of biodegradable gelatin
Introducing labile ester bonds
Adding a high density of carboxyl groups
Explanation - PEG sterically hinders enzyme access and reduces hydrolytic degradation of the underlying polymer.
Correct answer is: Grafting with a hydrophilic PEG brush
Q.75 A surface coating that contains catechol groups and silver nanoparticles aims to achieve:
Improved mechanical stiffness
Combined strong adhesion to substrates and antibacterial activity
Electrical conductivity
Magnetic responsiveness
Explanation - Catechol ensures robust adhesion while silver nanoparticles provide antimicrobial properties.
Correct answer is: Combined strong adhesion to substrates and antibacterial activity
Q.76 When measuring the surface energy of a biomaterial after modification, you observe a decrease in the water contact angle from 80° to 30°. This indicates that the surface has become:
More hydrophobic
More hydrophilic
More electrically conductive
More magnetic
Explanation - A lower water contact angle reflects increased wettability and higher surface energy, characteristic of hydrophilic surfaces.
Correct answer is: More hydrophilic
Q.77 Which method is most suitable for depositing a thin, uniform layer of polydopamine on a curved implant surface?
Dip coating in an alkaline dopamine solution
Thermal evaporation
Ion implantation
Laser ablation
Explanation - Polydopamine forms spontaneously on immersed substrates under mild alkaline conditions, conforming to complex geometries.
Correct answer is: Dip coating in an alkaline dopamine solution
Q.78 A surface that is functionalized with anionic sulfonate groups is expected to:
Attract cationic proteins and improve cell adhesion
Repel all proteins
Become magnetic
Increase the material's melting point
Explanation - Anionic sulfonate groups can bind positively charged biomolecules, influencing protein adsorption and subsequent cell interactions.
Correct answer is: Attract cationic proteins and improve cell adhesion
Q.79 Which surface modification technique is capable of creating a gradient of bioactive molecule concentration without using masks?
Gradient dip‑coating using controlled withdrawal speed
Ion implantation
Thermal annealing
Bulk extrusion
Explanation - Varying the withdrawal speed during dip‑coating produces a thickness/concentration gradient of the coating material.
Correct answer is: Gradient dip‑coating using controlled withdrawal speed
Q.80 In a neural electrode, why is it important to minimize the modulus mismatch between the electrode surface and brain tissue?
To increase electrical resistance
To reduce chronic inflammation and tissue damage
To improve magnetic properties
To enhance thermal conductivity
Explanation - A softer, tissue‑matched surface reduces mechanical irritation, limiting glial scar formation and improving signal stability.
Correct answer is: To reduce chronic inflammation and tissue damage
Q.81 Which surface modification strategy is best suited to create a bioactive coating that releases nitric oxide (NO) in a sustained manner?
Embedding NO‑releasing silica nanoparticles in a polymer matrix
Applying a metallic gold layer
Grafting hydrophobic fluorocarbons
Thermal oxidation of the surface
Explanation - Silica nanoparticles can be loaded with NO donors; when dispersed in a polymer, they enable controlled, sustained NO release.
Correct answer is: Embedding NO‑releasing silica nanoparticles in a polymer matrix
Q.82 A surface coated with a thin layer of titanium nitride (TiN) is primarily intended to:
Increase corrosion resistance and provide a gold‑like appearance
Make the surface biodegradable
Enhance magnetic susceptibility
Reduce electrical conductivity
Explanation - TiN forms a hard, inert, conductive coating that also gives a gold‑colored finish, improving durability and aesthetics.
Correct answer is: Increase corrosion resistance and provide a gold‑like appearance
Q.83 Which surface modification technique can be employed to introduce specific peptide sequences onto a polymeric scaffold without affecting its bulk mechanical properties?
Bulk melt blending
Surface grafting via carbodiimide chemistry
Thermal curing
Ion implantation
Explanation - Carbodiimide coupling attaches peptides directly to surface carboxyl groups, preserving the scaffold’s bulk strength.
Correct answer is: Surface grafting via carbodiimide chemistry
Q.84 Which of the following is a typical benefit of using a layer‑by‑layer (LbL) assembly for drug‑eluting stent coatings?
Single‑burst release of the entire drug load
Precise control over release kinetics by adjusting layer composition and number
Permanent, non‑degradable coating
Increased electrical resistance
Explanation - LbL allows tailoring of drug release profiles through the choice of polymers and number of deposited layers.
Correct answer is: Precise control over release kinetics by adjusting layer composition and number
Q.85 When a polymer surface is functionalized with a perfluorinated silane, the expected change in surface properties is:
Increased hydrophilicity
Decreased surface energy and increased hydrophobicity
Improved electrical conductivity
Enhanced protein adsorption
Explanation - Perfluorinated chains are highly non‑polar, reducing surface energy and making the surface water‑repellent.
Correct answer is: Decreased surface energy and increased hydrophobicity
Q.86 Which surface modification method can simultaneously provide antimicrobial activity and promote osteogenesis on a bone implant?
Grafting of silver nanoparticles only
Coating with a composite of hydroxyapatite and silver ions
Applying a thick silicone layer
Thermal oxidation
Explanation - Hydroxyapatite supports bone growth, while silver provides antimicrobial protection, delivering a dual function.
Correct answer is: Coating with a composite of hydroxyapatite and silver ions
Q.87 A surface modified with a high density of amino (–NH₂) groups at physiological pH will most likely:
Carry a net negative charge
Carry a net positive charge and attract negatively charged biomolecules
Become highly hydrophobic
Resist all protein adsorption
Explanation - Amino groups are protonated at physiological pH, giving the surface a positive charge that can bind anionic species.
Correct answer is: Carry a net positive charge and attract negatively charged biomolecules
Q.88 Which technique is best suited for creating a conformal coating on the internal lumen of a long polymeric catheter?
Atomic layer deposition (ALD)
Sputter coating
Spin coating
Dip coating
Explanation - ALD provides uniform, pinhole‑free films even inside high‑aspect‑ratio structures like catheters.
Correct answer is: Atomic layer deposition (ALD)
Q.89 A biomaterial surface that exhibits a water contact angle of 0° after modification is considered:
Superhydrophobic
Superhydrophilic
Hydrophobic
Neutral
Explanation - A contact angle of 0° means water spreads completely, indicating extreme hydrophilicity.
Correct answer is: Superhydrophilic
Q.90 Which surface modification technique is most appropriate for attaching a DNA probe onto a glass slide for a microarray?
Physical vapor deposition of gold
Silane functionalization followed by covalent coupling of the DNA
Thermal annealing at high temperature
Ion implantation of nitrogen
Explanation - Aminosilanes enable covalent attachment of DNA probes via stable amide bonds, essential for microarray reliability.
Correct answer is: Silane functionalization followed by covalent coupling of the DNA
Q.91 A surface coating that releases an anti‑inflammatory drug in response to a specific enzymatic trigger is an example of:
Passive diffusion coating
Stimuli‑responsive (smart) coating
Permanent inert coating
Electrical conductive coating
Explanation - Smart coatings release their payload only when a specific physiological cue (e.g., enzyme) is present, providing targeted therapy.
Correct answer is: Stimuli‑responsive (smart) coating
Q.92 Which surface modification can reduce the immunogenic response of a polymeric scaffold used for soft tissue regeneration?
Coating with a dense PEG brush layer
Roughening the surface with sandblasting
Embedding iron particles
Applying a thick metallic film
Explanation - PEG brushes create a hydration layer that limits protein adsorption and immune cell activation.
Correct answer is: Coating with a dense PEG brush layer
Q.93 When a titanium surface is anodized to form TiO₂ nanotubes, the expected biological benefit is:
Improved electrical conductivity for nerve stimulation
Enhanced osteogenic differentiation due to increased surface area
Reduced mechanical strength
Increased magnetic susceptibility
Explanation - TiO₂ nanotube arrays provide nanoscale topography that promotes osteoblast adhesion and differentiation.
Correct answer is: Enhanced osteogenic differentiation due to increased surface area
Q.94 A surface that has been treated with a zwitterionic polymer is primarily designed to:
Increase cell adhesion
Resist fouling by proteins and microorganisms
Conduct electricity
Increase surface roughness
Explanation - Zwitterionic polymers form strong hydration shells that prevent nonspecific adsorption, leading to anti‑fouling properties.
Correct answer is: Resist fouling by proteins and microorganisms
Q.95 Which of the following surface modification methods is most suitable for adding a thin, conductive graphene layer onto a polymeric substrate?
Spin coating of graphene oxide followed by reduction
Thermal oxidation
Ion implantation of carbon
Laser ablation
Explanation - Spin coating delivers a uniform graphene oxide film; subsequent chemical or thermal reduction converts it to conductive graphene.
Correct answer is: Spin coating of graphene oxide followed by reduction
Q.96 A surface modified with a high density of sulfhydryl (–SH) groups is especially useful for:
Covalent attachment of gold nanoparticles via Au–S bonds
Increasing surface hydrophobicity
Improving thermal conductivity
Making the surface magnetic
Explanation - Thiol groups bind strongly to gold surfaces, enabling stable immobilization of gold nanoparticles or other Au‑based structures.
Correct answer is: Covalent attachment of gold nanoparticles via Au–S bonds
Q.97 Which surface modification technique can be used to create a micro‑pattern of adhesive islands for guided cell migration?
Microcontact printing of ECM proteins
Bulk melt extrusion
Thermal annealing
Ion implantation
Explanation - Microcontact printing transfers biomolecules in defined patterns, allowing precise control over where cells can adhere and migrate.
Correct answer is: Microcontact printing of ECM proteins
Q.98 A surface that is coated with a thin layer of poly(L‑lactic acid) (PLLA) and subsequently functionalized with RGD peptides is primarily intended to:
Increase electrical conductivity
Provide a biodegradable matrix with enhanced cell adhesion
Make the surface magnetic
Reduce mechanical flexibility
Explanation - PLLA degrades safely in vivo, while RGD promotes cell attachment, together supporting tissue engineering applications.
Correct answer is: Provide a biodegradable matrix with enhanced cell adhesion
Q.99 When a polymer surface is treated with a fluorinated silane, the primary effect on protein adsorption is:
Increased adsorption due to hydrophobic interactions
Reduced adsorption because of low surface energy
No change in adsorption
Enhanced covalent binding of proteins
Explanation - Fluorinated surfaces are highly hydrophobic with low surface energy, discouraging protein attachment.
Correct answer is: Reduced adsorption because of low surface energy
Q.100 Which surface modification technique can create a gradient of stiffness across a hydrogel by varying cross‑link density?
Uniform UV exposure
Photopolymerization with a spatial light modulator (SLM)
Thermal curing in an oven
Bulk extrusion
Explanation - SLM allows spatial control of light intensity, generating regions with different cross‑link densities and thus varying stiffness.
Correct answer is: Photopolymerization with a spatial light modulator (SLM)
Q.101 A biomaterial surface that is modified to be superhydrophobic is expected to:
Promote rapid cell spreading
Resist wetting and reduce bacterial colonization in aqueous environments
Increase protein adsorption
Become electrically conductive
Explanation - Superhydrophobic surfaces repel water and can limit bacterial adhesion due to reduced contact area.
Correct answer is: Resist wetting and reduce bacterial colonization in aqueous environments
Q.102 Which surface modification approach is most appropriate for adding a thin, uniform, electrically conductive coating on a polymeric neural probe?
Electrochemical polymerization of polypyrrole
Thermal oxidation
Ion implantation of nitrogen
Laser ablation
Explanation - Electrochemical polymerization deposits conductive polypyrrole directly onto the probe surface with controllable thickness.
Correct answer is: Electrochemical polymerization of polypyrrole
Q.103 In surface modification, the term "bioactive” typically indicates that the surface:
Prevents any cellular interaction
Stimulates a specific biological response such as cell adhesion or differentiation
Is electrically conductive
Degrades within minutes
Explanation - Bioactive surfaces are designed to interact positively with biological systems, promoting desired outcomes.
Correct answer is: Stimulates a specific biological response such as cell adhesion or differentiation
Q.104 Which surface modification technique would you choose to create a durable, wear‑resistant coating on a polymeric joint component?
Diamond‑like carbon (DLC) deposition
Silane grafting of PEG
Thermal annealing at 200 °C
Ion implantation of helium
Explanation - DLC provides a hard, low‑friction coating that significantly improves wear resistance of polymer components.
Correct answer is: Diamond‑like carbon (DLC) deposition
Q.105 A surface functionalized with heparin is primarily intended to:
Promote bone formation
Provide anticoagulant properties to blood‑contacting devices
Increase electrical conductivity
Make the surface magnetic
Explanation - Heparin binds antithrombin and inhibits clotting, reducing thrombogenicity of devices such as catheters and stents.
Correct answer is: Provide anticoagulant properties to blood‑contacting devices
Q.106 When a polymer surface is modified by UV‑induced graft polymerization of acrylic acid, the dominant new functional group is:
Methyl (–CH₃)
Carboxyl (–COOH)
Silane (–Si–)
Amide (–CONH₂)
Explanation - Acrylic acid introduces pendant –COOH groups, increasing surface acidity and reactivity.
Correct answer is: Carboxyl (–COOH)
Q.107 A surface modified with a dense layer of poly(ethylene glycol) (PEG) is most likely to:
Enhance bacterial adhesion
Resist protein adsorption and cell adhesion
Increase electrical conductivity
Become magnetically active
Explanation - PEG forms a hydrated steric barrier that repels proteins and cells, providing antifouling properties.
Correct answer is: Resist protein adsorption and cell adhesion
Q.108 Which surface modification method can be used to create a hierarchical micro‑/nano‑structure that mimics the extracellular matrix?
Electrospinning combined with plasma etching
Thermal annealing alone
Bulk extrusion
Ion implantation
Explanation - Electrospun fibers provide micro‑scale architecture; plasma etching adds nano‑scale roughness, together resembling ECM.
Correct answer is: Electrospinning combined with plasma etching
Q.109 A surface coating that releases nitric oxide (NO) in response to physiological triggers is categorized as:
Passive diffusion coating
Stimuli‑responsive (smart) coating
Permanent inert coating
Conductive coating
Explanation - The coating releases NO upon specific stimuli (e.g., pH, enzymes), providing on‑demand therapeutic action.
Correct answer is: Stimuli‑responsive (smart) coating
Q.110 Which analytical method provides quantitative information about the amount of nitrogen on a surface after plasma nitridation?
X‑ray photoelectron spectroscopy (XPS)
Atomic force microscopy (AFM)
Thermogravimetric analysis (TGA)
Differential scanning calorimetry (DSC)
Explanation - XPS can detect elemental composition and chemical states, allowing quantification of surface nitrogen.
Correct answer is: X‑ray photoelectron spectroscopy (XPS)
Q.111 Which surface modification technique is most appropriate for adding a thin, uniform, conductive polymer layer onto a flexible polymeric substrate without heating it?
Electrochemical polymerization
Thermal evaporation
Sputter deposition at high temperature
Ion implantation
Explanation - Electrochemical polymerization occurs at room temperature and can coat flexible substrates uniformly.
Correct answer is: Electrochemical polymerization
Q.112 A surface modified with a high density of sulfonic acid groups will most likely:
Increase hydrophobicity
Be strongly acidic and attract basic biomolecules
Become magnetic
Reduce surface energy
Explanation - Sulfonic acid groups are strong acids, imparting negative charge that can bind positively charged species.
Correct answer is: Be strongly acidic and attract basic biomolecules
Q.113 Which surface modification method is widely used to create a bio‑inert, corrosion‑resistant oxide layer on titanium alloys?
Anodization
Ion implantation of gold
Thermal annealing at 900 °C
Plasma polymerization of PTFE
Explanation - Anodization forms a thick, stable TiO₂ oxide layer that is bio‑inert and improves corrosion resistance.
Correct answer is: Anodization
Q.114 When a polymer surface is functionalized with a high density of carboxyl groups, it is best suited for:
Covalent attachment of amine‑containing biomolecules via carbodiimide chemistry
Increasing hydrophobicity
Making the surface magnetic
Reducing mechanical strength
Explanation - Carboxyl groups react with amines in the presence of EDC/NHS, forming stable amide bonds for biomolecule immobilization.
Correct answer is: Covalent attachment of amine‑containing biomolecules via carbodiimide chemistry
Q.115 Which surface modification approach can be used to introduce a reversible, pH‑responsive switching of surface charge?
Grafting of poly(2‑dimethylamino)ethyl methacrylate (PDMAEMA)
Silane fluorination
Thermal annealing
Ion implantation of inert gases
Explanation - PDMAEMA protonates under acidic conditions (positive charge) and deprotonates under basic conditions (neutral), enabling pH‑responsive charge switching.
Correct answer is: Grafting of poly(2‑dimethylamino)ethyl methacrylate (PDMAEMA)
Q.116 A surface that is coated with a thin layer of TiN (titanium nitride) will most likely exhibit:
Increased corrosion resistance and a gold‑like appearance
Magnetic properties
Reduced hardness
Rapid degradation in vivo
Explanation - TiN provides a hard, chemically stable coating with a characteristic golden color, enhancing durability.
Correct answer is: Increased corrosion resistance and a gold‑like appearance
Q.117 Which surface modification technique can be used to attach biomolecules via a click‑type azide‑alkyne reaction without the need for metal catalysts?
Strain‑promoted azide‑alkyne cycloaddition (SPAAC)
Thermal oxidation
Sputter deposition of gold
Ion implantation
Explanation - SPAAC is a copper‑free click reaction that proceeds under mild, aqueous conditions, ideal for sensitive biomolecules.
Correct answer is: Strain‑promoted azide‑alkyne cycloaddition (SPAAC)
Q.118 A surface modified with a high density of amine groups (–NH₂) at physiological pH will tend to:
Repel positively charged proteins
Bind negatively charged proteins and nucleic acids
Become highly hydrophobic
Increase mechanical stiffness
Explanation - Protonated amine groups are positively charged, attracting negatively charged biomolecules.
Correct answer is: Bind negatively charged proteins and nucleic acids
Q.119 Which technique is most suitable for creating a nanoscale, ordered pattern of metal islands on a polymer surface for plasmonic applications?
Nanoimprint lithography
Bulk extrusion
Thermal annealing
Ion implantation
Explanation - Nanoimprint lithography can transfer nanoscale patterns into a resist, followed by metal deposition to form ordered islands.
Correct answer is: Nanoimprint lithography
Q.120 A surface coating that combines a hydroxyapatite layer with immobilized BMP‑2 growth factor is designed to:
Promote antibacterial activity while reducing bone formation
Enhance bone regeneration by providing both a mineral scaffold and osteoinductive signals
Increase electrical conductivity for nerve stimulation
Make the implant magnetic
Explanation - Hydroxyapatite offers a bone‑like matrix, while BMP‑2 stimulates osteogenic differentiation, together accelerating healing.
Correct answer is: Enhance bone regeneration by providing both a mineral scaffold and osteoinductive signals
Q.121 When a polymer surface is treated with a fluorinated silane, the most likely impact on cellular adhesion is:
Increased cell adhesion due to hydrophobic interactions
Decreased cell adhesion because of reduced protein adsorption
No change in adhesion
Conversion of the surface to a conductive state
Explanation - Fluorinated surfaces are highly hydrophobic, discouraging protein adsorption and consequently cell attachment.
Correct answer is: Decreased cell adhesion because of reduced protein adsorption
Q.122 Which surface modification technique is particularly advantageous for creating a thin, conformal, and electrically conductive coating on a flexible polymer electrode?
Atomic layer deposition (ALD) of a metal oxide
Electrochemical polymerization of polypyrrole
Thermal vapor deposition at >400 °C
Ion implantation of argon
Explanation - Polypyrrole can be polymerized directly onto flexible substrates at low temperature, forming a conductive film.
Correct answer is: Electrochemical polymerization of polypyrrole
Q.123 A surface functionalized with a high density of sulfobetaine groups is expected to:
Increase protein adsorption
Provide antifouling properties due to zwitterionic nature
Make the surface magnetic
Reduce mechanical strength
Explanation - Sulfobetaine contains both positive and negative charges, creating strong hydration that repels proteins and cells.
Correct answer is: Provide antifouling properties due to zwitterionic nature
Q.124 Which surface modification method can be employed to graft a polymer brush that resists both protein adsorption and bacterial adhesion?
Grafting‑to approach using pre‑synthesized PEG brushes
Bulk melt extrusion
Thermal oxidation
Ion implantation
Explanation - PEG brushes, attached via grafting‑to chemistry, create dense, hydrated layers that deter fouling.
Correct answer is: Grafting‑to approach using pre‑synthesized PEG brushes
Q.125 A surface-modified orthopedic screw that releases vancomycin in response to bacterial enzymes exemplifies which design concept?
Passive diffusion coating
Stimuli‑responsive (smart) antimicrobial coating
Permanent inert coating
Conductive coating
Explanation - The coating releases the antibiotic only when bacterial enzymes are present, providing targeted infection control.
Correct answer is: Stimuli‑responsive (smart) antimicrobial coating
Q.126 Which of the following surface modifications is most likely to improve the long‑term stability of a polymeric scaffold in a physiological environment?
Grafting of hydrolytically stable silane groups
Increasing surface roughness with sandblasting
Embedding metal particles
Applying a thin layer of water‑soluble gelatin
Explanation - Silane coupling creates strong covalent bonds that are resistant to hydrolysis, enhancing durability in vivo.
Correct answer is: Grafting of hydrolytically stable silane groups
Q.127 A surface modified with a dense layer of zwitterionic polymers will most likely exhibit:
Enhanced osteogenic differentiation
Reduced fouling due to strong hydration
Increased electrical conductivity
Higher hydrophobicity
Explanation - Zwitterionic polymers form tightly bound water layers that prevent nonspecific adsorption of proteins and microbes.
Correct answer is: Reduced fouling due to strong hydration
Q.128 Which surface modification technique can be used to introduce nitrogen‑containing functional groups onto a polymer surface without affecting its bulk properties?
Plasma nitridation
Thermal annealing at 300 °C
Bulk extrusion with nitrogen gas
Ion implantation of gold
Explanation - Plasma nitridation creates reactive nitrogen species that modify only the surface layer, preserving bulk characteristics.
Correct answer is: Plasma nitridation
Q.129 Which method provides the most precise control over film thickness at the atomic level for surface coatings on biomaterials?
Atomic layer deposition (ALD)
Spin coating
Dip coating
Thermal spray
Explanation - ALD deposits material one atomic layer at a time, allowing sub‑nanometer thickness control.
Correct answer is: Atomic layer deposition (ALD)
Q.130 A surface that is grafted with a polymer containing pendant carboxyl groups will likely:
Be positively charged at physiological pH
Bind positively charged proteins via electrostatic interaction
Become highly hydrophobic
Resist any chemical modification
Explanation - Carboxyl groups are negatively charged at physiological pH, attracting positively charged biomolecules.
Correct answer is: Bind positively charged proteins via electrostatic interaction
Q.131 Which surface modification technique can be used to create a superhydrophilic surface that promotes rapid endothelial cell spreading on a vascular graft?
Plasma oxidation to introduce –OH groups
Silane fluorination
Thermal annealing at high temperature
Embedding magnetic particles
Explanation - Plasma oxidation adds polar hydroxyl groups, lowering water contact angle and fostering endothelial cell attachment.
Correct answer is: Plasma oxidation to introduce –OH groups
Q.132 Which surface modification strategy is most effective for creating a conductive, biodegradable coating for transient electronic implants?
Coating with polylactic acid (PLA) blended with carbon nanotubes
Applying a permanent gold film
Silane fluorination
Thermal oxidation
Explanation - PLA degrades safely, while carbon nanotubes confer conductivity, enabling temporary electronic functionality.
Correct answer is: Coating with polylactic acid (PLA) blended with carbon nanotubes