Introduction to liposomes and their applications MCQs With Answer

Introduction to liposomes and their applications MCQs With Answer

Liposomes are spherical vesicles composed of phospholipid bilayers that encapsulate aqueous cores, widely used in drug delivery and nanomedicine. For B. Pharm students, understanding liposome composition, preparation methods (thin-film hydration, reverse-phase evaporation, ethanol injection), encapsulation strategies (passive and active loading), and characterization techniques (DLS, TEM, entrapment efficiency) is essential. Key concepts include cholesterol’s role in membrane stability, PEGylation for prolonged circulation, targeted delivery, controlled release mechanisms, and clinical applications such as anticancer formulations and vaccines. Regulatory, sterilization, and scale-up challenges are also important. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the primary structural component forming the bilayer of conventional liposomes?

• Cholesterol
• Sodium alginate
• Phospholipids
• Polyethylene glycol

Correct Answer: Phospholipids

Q2. Which region of a liposome primarily encapsulates hydrophilic drugs?

• Lipid bilayer
• Aqueous core
• Surface PEG layer
• Hydrophobic tails

Correct Answer: Aqueous core

Q3. Which lipid additive is commonly used to increase membrane rigidity and reduce permeability?

• Sodium dodecyl sulfate
• Cholesterol
• Polyethylene glycol
• Polyvinyl alcohol

Correct Answer: Cholesterol

Q4. Which preparation method involves dissolving lipids in organic solvent, forming a thin film, then hydrating it?

• Reverse-phase evaporation
• Thin-film hydration (Bangham) method
• Ethanol injection
• Detergent removal

Correct Answer: Thin-film hydration (Bangham) method

Q5. What does PEGylation of liposomes primarily achieve?

• Increase drug crystallization inside core
• Shorten circulation half-life
• Provide stealth properties and reduce RES uptake
• Make liposomes more cationic

Correct Answer: Provide stealth properties and reduce RES uptake

Q6. Passive encapsulation is most effective for which type of drug during liposome preparation?

• Hydrophobic drugs that partition into the bilayer
• Hydrophilic drugs present in the hydration medium
• Large plasmid DNA
• Gas molecules

Correct Answer: Hydrophilic drugs present in the hydration medium

Q7. Which technique measures liposome size distribution by analyzing light scattering intensity fluctuations?

• Transmission electron microscopy (TEM)
• Dynamic light scattering (DLS)
• High-performance liquid chromatography (HPLC)
• Nuclear magnetic resonance (NMR)

Correct Answer: Dynamic light scattering (DLS)

Q8. Remote (active) loading of weakly basic drugs into liposomes typically exploits which gradient?

• Hyperosmotic gradient
• pH or ion gradient (e.g., ammonium sulfate)
• Temperature gradient
• Electrochemical gradient across the bilayer

Correct Answer: pH or ion gradient (e.g., ammonium sulfate)

Q9. Which of the following is an FDA-approved liposomal anticancer product?

• Dexamethasone liposome
• Doxil (liposomal doxorubicin)
• Liposomal paracetamol
• Paclitaxel microemulsion

Correct Answer: Doxil (liposomal doxorubicin)

Q10. What is the effect of increasing lipid concentration on liposome size during thin-film hydration?

• Always decreases size due to better dispersion
• Generally increases size and lamellarity
• Has no effect on size
• Converts liposomes to micelles

Correct Answer: Generally increases size and lamellarity

Q11. Which liposome type has multiple concentric bilayers like an onion?

• Small unilamellar vesicle (SUV)
• Large unilamellar vesicle (LUV)
• Multilamellar vesicle (MLV)
• Reverse micelle

Correct Answer: Multilamellar vesicle (MLV)

Q12. For gene delivery, which characteristic of liposomes is most desirable?

• Neutral charge and large size
• Cationic surface charge for complexing nucleic acids
• High cholesterol content to prevent endosomal escape
• High PEGylation to prevent cellular uptake

Correct Answer: Cationic surface charge for complexing nucleic acids

Q13. Which analytical method provides direct visualization of liposome morphology and lamellarity?

• Dynamic light scattering (DLS)
• Transmission electron microscopy (TEM) or cryo-TEM
• UV-Visible spectroscopy
• Zeta potential measurement

Correct Answer: Transmission electron microscopy (TEM) or cryo-TEM

Q14. Entrapment efficiency (%) refers to:

• Percentage of total lipid retained after purification
• Percentage of initial drug that is encapsulated in liposomes
• Percentage of PEG chains on the surface
• Percentage of liposomes that are multilamellar

Correct Answer: Percentage of initial drug that is encapsulated in liposomes

Q15. Which statement best describes the Enhanced Permeability and Retention (EPR) effect relevant to liposomal delivery?

• Targeted binding to specific cell-surface receptors
• Preferential accumulation of nanosized carriers in tumor tissue due to leaky vasculature
• Rapid renal clearance of liposomes under 200 nm
• Improved oral absorption through intestinal pores

Correct Answer: Preferential accumulation of nanosized carriers in tumor tissue due to leaky vasculature

Q16. Which stabilizer is commonly used during lyophilization of liposomes to preserve structure?

• Glucose oxidase
• Talc
• Sucrose or trehalose (cryoprotectants)
• Sodium dodecyl sulfate

Correct Answer: Sucrose or trehalose (cryoprotectants)

Q17. What is the primary reason for including charged lipids in liposome formulation?

• To make liposomes edible
• To control surface charge, stability, and interactions with biological membranes
• To increase drug crystallinity
• To reduce entrapment efficiency

Correct Answer: To control surface charge, stability, and interactions with biological membranes

Q18. Temperature-sensitive (thermosensitive) liposomes release drug primarily in response to:

• Changes in external pH
• Local hyperthermia or elevated temperature
• Enzymatic degradation by lipase only
• Exposure to electromagnetic fields only

Correct Answer: Local hyperthermia or elevated temperature

Q19. Which parameter is measured by zeta potential analysis of liposomes?

• Hydrodynamic diameter
• Surface charge and colloidal stability
• Entrapment efficiency
• Lipid phase transition temperature

Correct Answer: Surface charge and colloidal stability

Q20. Reverse-phase evaporation method is particularly suitable for:

• Producing SUVs with extremely small sizes only
• High encapsulation of aqueous-soluble macromolecules
• Formulating only hydrophobic drugs into the bilayer
• Direct sterilization by heat

Correct Answer: High encapsulation of aqueous-soluble macromolecules

Q21. Which lipid headgroup is a common zwitterionic phospholipid used in liposomes?

• Phosphatidylcholine (PC)
• Phosphatidylserine (PS)
• Phosphatidic acid (PA)
• Cardiolipin

Correct Answer: Phosphatidylcholine (PC)

Q22. A major biological clearance pathway for conventional liposomes involves uptake by:

• Renal glomeruli filtration
• Reticuloendothelial system (RES) / mononuclear phagocyte system (MPS)
• Cerebrospinal fluid drainage
• Intestinal epithelial cells

Correct Answer: Reticuloendothelial system (RES) / mononuclear phagocyte system (MPS)

Q23. Which modification can enhance liposome circulation time and reduce opsonization?

• Increasing multilamellarity
• Incorporating PEGylated lipids (stealth liposomes)
• Adding high concentrations of cholesterol only
• Using anionic detergents in formulation

Correct Answer: Incorporating PEGylated lipids (stealth liposomes)

Q24. Encapsulation of amphotericin B in liposomes (e.g., Ambisome) primarily improves therapy by:

• Increasing renal toxicity
• Reducing toxicity and improving targeted delivery to infected tissues
• Making the drug inactive
• Preventing drug binding to fungal membranes

Correct Answer: Reducing toxicity and improving targeted delivery to infected tissues

Q25. Which release mechanism describes drug diffusion across the liposomal bilayer without liposome disruption?

• Fusion-mediated release only
• Permeation/diffusion-controlled release
• Immediate burst from ruptured liposomes
• Enzymatic cleavage of PEG chains only

Correct Answer: Permeation/diffusion-controlled release

Q26. What role does cholesterol play in liposome formulations at physiological temperature?

• Prevents bilayer formation entirely
• Modulates membrane fluidity and decreases permeability
• Acts as a cryoprotectant during freeze-drying
• Adds positive charge to the membrane

Correct Answer: Modulates membrane fluidity and decreases permeability

Q27. Which of the following is a critical quality attribute assessed during liposome characterization for regulatory submissions?

• Color under UV light
• Particle size distribution, encapsulation efficiency, and sterility
• Number of multilamellar layers only
• Manufacturer’s logo clarity

Correct Answer: Particle size distribution, encapsulation efficiency, and sterility

Q28. Which method is commonly used to remove unencapsulated drug after liposome formation?

• Dialysis, gel filtration (size-exclusion chromatography), or ultracentrifugation
• Direct heating to 100°C
• Adding acid to precipitate lipids
• Ion exchange chromatography targeting PEG

Correct Answer: Dialysis, gel filtration (size-exclusion chromatography), or ultracentrifugation

Q29. In formulation design, what is a major challenge when scaling up liposome production?

• Maintaining particle size, encapsulation efficiency, and batch-to-batch reproducibility
• Finding organic solvents that dissolve water only
• Preventing all lipids from forming crystals
• Eliminating the need for sterile conditions

Correct Answer: Maintaining particle size, encapsulation efficiency, and batch-to-batch reproducibility

Q30. Which liposome property most directly influences extravasation into tumor tissue via the EPR effect?

• Surface color
• Hydrodynamic diameter (size), typically 50–200 nm
• Number of double bonds in fatty acid chains only
• Presence of fluorescent dye

Correct Answer: Hydrodynamic diameter (size), typically 50–200 nm

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com