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
