Nanoparticles: types and preparation MCQs With Answer

Nanoparticles: types and preparation MCQs With Answer (M.Pharm – Molecular Pharmaceutics / NTDS)

Nanoparticles are central to modern drug delivery, enabling targeted therapy, improved solubility, and controlled release. For M.Pharm students, mastering their types—polymeric nanospheres/capsules, solid lipid nanoparticles, nanostructured lipid carriers, dendrimers, micelles, metallic nanoparticles, and more—and preparation methods—nanoprecipitation, emulsion-based techniques, miniemulsion polymerization, ionic gelation, antisolvent precipitation, and top-down approaches—is essential. This MCQ set tests conceptual depth and practical understanding of solvent choices, interfacial phenomena, surfactants, process parameters, stabilization, and scale-up considerations. You will encounter questions on zeta potential, PDI, cryoprotection, Ostwald ripening, green synthesis, and PEGylation—designed to sharpen your analytical skills for research and exams. Review each explanation as a quick refresher and use these questions to identify knowledge gaps and strengthen core competencies.

Q1. Which statement best distinguishes nanospheres from nanocapsules in polymeric nanoparticle systems?

• Nanospheres are matrix systems with drug uniformly dispersed; nanocapsules are reservoir systems with drug confined to a core
• Nanospheres always have a lipid core; nanocapsules always have a polymer core
• Nanospheres are hollow vesicles; nanocapsules are solid particles
• Nanospheres are prepared only by emulsion methods; nanocapsules only by nanoprecipitation

Correct Answer: Nanospheres are matrix systems with drug uniformly dispersed; nanocapsules are reservoir systems with drug confined to a core

Q2. In nanoprecipitation (solvent displacement) for PLGA nanoparticles, which solvent pairing is most appropriate?

• Polymer in acetone (miscible with water) added to an aqueous surfactant solution under stirring
• Polymer in dichloromethane (immiscible with water) added to aqueous phase without surfactant
• Polymer in mineral oil added to ethanol under ultrasonication
• Polymer in water added to hexane containing surfactant

Correct Answer: Polymer in acetone (miscible with water) added to an aqueous surfactant solution under stirring

Q3. Emulsion–solvent evaporation for polymeric nanoparticles generally relies on which principle?

• Formation of an oil-in-water emulsion using a volatile, water-immiscible organic solvent that is later evaporated
• Direct crystallization of drug from a supersaturated aqueous solution without organic solvent
• Self-assembly of amphiphilic polymers above critical micelle concentration
• Crosslinking of polysaccharides using multivalent counterions

Correct Answer: Formation of an oil-in-water emulsion using a volatile, water-immiscible organic solvent that is later evaporated

Q4. In hot high-pressure homogenization (HPH) for solid lipid nanoparticles (SLNs), which step is essential?

• Disperse molten lipid in a hot surfactant solution, homogenize at elevated temperature, then cool to solidify nanoparticles
• Dissolve lipid in acetone and dropwise add into cold water to precipitate
• React lipid with diamine at the interface to form a polyamide shell
• Freeze-dry lipid powder and reconstitute with saline

Correct Answer: Disperse molten lipid in a hot surfactant solution, homogenize at elevated temperature, then cool to solidify nanoparticles

Q5. Ionic gelation for chitosan nanoparticles typically uses which crosslinking agent?

• Sodium tripolyphosphate (TPP)
• Calcium chloride
• Glutaraldehyde
• N,N′-Methylenebisacrylamide

Correct Answer: Sodium tripolyphosphate (TPP)

Q6. A key advantage of miniemulsion polymerization for nanocapsule formation is:

• Droplet nucleation allowing high encapsulation of hydrophobic actives and narrower size distribution
• Elimination of surfactants while maintaining stability
• Production of thermodynamically stable dispersions
• Exclusive use of water-miscible solvents

Correct Answer: Droplet nucleation allowing high encapsulation of hydrophobic actives and narrower size distribution

Q7. PEGylation of nanoparticles primarily leads to:

• Reduced opsonization and prolonged systemic circulation by imparting a stealth corona
• Accelerated cellular uptake via enhanced electrostatic attraction
• Immediate endosomal escape due to proton sponge effect
• Increased crystallinity of the nanoparticle core

Correct Answer: Reduced opsonization and prolonged systemic circulation by imparting a stealth corona

Q8. For PLGA nanoparticles, increasing the lactic:glycolic ratio generally results in:

• Slower degradation and more hydrophobic polymer matrix
• Faster degradation due to increased hydrophilicity
• No change in degradation rate but increased glass transition temperature
• Complete suppression of autocatalysis

Correct Answer: Slower degradation and more hydrophobic polymer matrix

Q9. In dynamic light scattering (DLS), which polydispersity index (PDI) value is typically indicative of a narrowly distributed nanoparticle sample?

• PDI ≤ 0.2
• PDI ≈ 0.5
• PDI ≥ 0.7
• PDI between 0.3 and 0.6

Correct Answer: PDI ≤ 0.2

Q10. What zeta potential magnitude is commonly associated with good electrostatic stabilization of aqueous nanoparticle dispersions (without steric stabilizers)?

• |ζ| ≥ 30 mV
• |ζ| ≥ 5 mV
• |ζ| ≥ 10 mV
• |ζ| ≥ 15 mV

Correct Answer: |ζ| ≥ 30 mV

Q11. Which statement correctly contrasts nanoemulsions and microemulsions?

• Microemulsions are thermodynamically stable; nanoemulsions are kinetically stable
• Nanoemulsions require very high surfactant fractions; microemulsions do not
• Both systems are thermodynamically stable
• Microemulsions always have larger droplet sizes than nanoemulsions

Correct Answer: Microemulsions are thermodynamically stable; nanoemulsions are kinetically stable

Q12. In antisolvent precipitation for drug nanosuspensions, which condition most effectively reduces particle size?

• High supersaturation with rapid mixing to favor nucleation over growth
• Low supersaturation with slow mixing to favor crystal growth
• Use of high-viscosity solvents to slow diffusion
• Elevated temperature to increase solubility during precipitation

Correct Answer: High supersaturation with rapid mixing to favor nucleation over growth

Q13. The primary role of a co-surfactant (e.g., short-chain alcohol) in microemulsion formation is to:

• Reduce interfacial tension and increase interfacial film flexibility to expand the microemulsion region
• Increase the critical micelle concentration of the main surfactant
• Crystallize the oil phase to stabilize droplets
• Neutralize charges on nanoparticles to increase aggregation

Correct Answer: Reduce interfacial tension and increase interfacial film flexibility to expand the microemulsion region

Q14. In green synthesis of metallic nanoparticles using plant extracts, phytochemicals mainly function as:

• Both reducing agents and capping/stabilizing agents
• Only as acidic catalysts for hydrolysis
• Only as hydrotropes to increase metal salt solubility
• Only as crosslinkers for polymer shells

Correct Answer: Both reducing agents and capping/stabilizing agents

Q15. During lyophilization of polymeric nanoparticles, which additive is most appropriate as a cryoprotectant to prevent aggregation?

• Trehalose
• Sodium dodecyl sulfate
• Hydrochloric acid
• Toluene

Correct Answer: Trehalose

Q16. Ostwald ripening in lipid nanoparticles can be minimized by:

• Using poorly water-soluble lipids and creating imperfect matrices (e.g., NLC with mixed solid/liquid lipids)
• Increasing temperature to accelerate molecular diffusion
• Replacing lipids with highly water-soluble oils
• Eliminating all surfactants to reduce micellar solubilization

Correct Answer: Using poorly water-soluble lipids and creating imperfect matrices (e.g., NLC with mixed solid/liquid lipids)

Q17. In the emulsion–diffusion method, what is the purpose of pre-saturating the aqueous phase with the organic solvent (and vice versa)?

• To control solvent diffusion, reduce interfacial turbulence, and promote uniform nanoparticle formation
• To eliminate the need for surfactants completely
• To increase the volatility of the organic solvent
• To precipitate the polymer before emulsification

Correct Answer: To control solvent diffusion, reduce interfacial turbulence, and promote uniform nanoparticle formation

Q18. Which technique is a top-down approach for producing drug nanosuspensions?

• Wet media milling (pearl milling) of coarse drug crystals
• Nanoprecipitation from acetone into water
• Interfacial polymerization of monomers
• Ionic gelation of chitosan with TPP

Correct Answer: Wet media milling (pearl milling) of coarse drug crystals

Q19. Interfacial polymerization to form polyamide nanocapsules typically involves which monomer pair at the oil–water interface?

• Hexamethylenediamine and sebacoyl chloride
• Acrylic acid and potassium persulfate
• Glycerol and terephthalic acid
• Ethylene oxide and propylene oxide

Correct Answer: Hexamethylenediamine and sebacoyl chloride

Q20. For formulating oil-in-water nanoemulsions, which surfactant property is generally preferred?

• High HLB surfactant (e.g., Tween 80) suitable for o/w systems
• Low HLB surfactant (e.g., Span 80) to stabilize o/w droplets
• Nonionic surfactant with HLB ≈ 2 for maximum micellization
• Cationic surfactant exclusively to provide electrostatic stabilization

Correct Answer: High HLB surfactant (e.g., Tween 80) suitable for o/w systems

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