Liposomal gene delivery MCQs With Answer

Introduction

Liposomal gene delivery combines the biocompatibility of lipid vesicles with nucleic acid therapeutics to enable efficient intracellular delivery of DNA, mRNA, siRNA and gene-editing tools. This short quiz set for M.Pharm students focuses on critical concepts: liposome composition, preparation methods, mechanisms of cellular uptake and endosomal escape, characterization parameters, formulation challenges, in vivo behavior, targeting strategies and regulatory considerations. Questions are designed to deepen understanding of how lipid chemistry, surface modification, size, charge and helper lipids influence transfection efficiency, stability, toxicity and biodistribution. Reviewing these MCQs will help students bridge theoretical knowledge and practical formulation choices in designing liposomal gene delivery systems.

Q1. Which lipid component is most commonly used to provide structural rigidity and membrane ordering in liposomal formulations for gene delivery?

• DOPE (dioleoyl phosphatidylethanolamine)
• DOTAP (dioleoyl trimethylammonium propane)
• Cholesterol
• PEGylated DSPE

Correct Answer: Cholesterol

Q2. Which ionizable lipid property is most desirable for systemic mRNA delivery to enhance in vivo tolerability while allowing endosomal escape?

• Constitutively cationic at physiological pH
• Neutral at physiological pH and protonated in endosomes
• Highly anionic at all pH values
• Irreversibly crosslinked after administration

Correct Answer: Neutral at physiological pH and protonated in endosomes

Q3. Which helper lipid is frequently used to facilitate membrane fusion and promote endosomal escape of nucleic acids from liposomes?

• DSPC (distearoyl phosphatidylcholine)
• DOPE (dioleoyl phosphatidylethanolamine)
• DSPE-PEG2000
• Cholesteryl hemisuccinate

Correct Answer: DOPE (dioleoyl phosphatidylethanolamine)

Q4. In a thin-film hydration method for liposome preparation, which step most directly determines encapsulation efficiency of plasmid DNA?

• Hydration volume and ionic strength during rehydration
• Rate of organic solvent evaporation
• Temperature of lipid film formation
• Type of glassware used for drying

Correct Answer: Hydration volume and ionic strength during rehydration

Q5. What is the primary purpose of PEGylation (attachment of PEG chains) on liposomal surfaces in systemic gene delivery?

• Increase cationic charge to enhance cellular uptake
• Promote rapid clearance by the reticuloendothelial system
• Reduce protein adsorption and prolong circulation time
• Cause immediate endosomal rupture after uptake

Correct Answer: Reduce protein adsorption and prolong circulation time

Q6. Which physicochemical parameter is most predictive of colloidal stability and aggregation risk for liposomal gene formulations?

• Zeta potential
• Optical rotation
• Glass transition temperature of lyophilized cake
• Aqueous pH only

Correct Answer: Zeta potential

Q7. For delivering siRNA intracellularly, what advantage do cationic liposomes provide compared to neutral liposomes?

• Reduced serum nuclease protection
• Enhanced electrostatic complexation and cellular uptake
• Lower cytotoxicity in most cell types
• Improved renal clearance

Correct Answer: Enhanced electrostatic complexation and cellular uptake

Q8. Which of the following cationic lipids is commonly used in laboratory transfection reagents and noted for efficient plasmid delivery?

• DOTAP (1,2-dioleoyl-3-trimethylammonium-propane)
• DSPC (1,2-distearoyl-sn-glycero-3-phosphocholine)
• Cholesterol hemisuccinate
• DSPE-PEG2000

Correct Answer: DOTAP (1,2-dioleoyl-3-trimethylammonium-propane)

Q9. Which analytical technique is most suitable for determining the lamellarity and internal aqueous volume of liposomes used for gene encapsulation?

• Dynamic light scattering (DLS)
• Cryogenic transmission electron microscopy (cryo-TEM)
• UV-visible spectroscopy at 260 nm
• Zeta potential measurement

Correct Answer: Cryogenic transmission electron microscopy (cryo-TEM)

Q10. What is a common strategy to achieve targeted delivery of liposomal nucleic acids to hepatocytes in vivo?

• Decoration with transferrin ligands
• Incorporation of galactose or N-acetylgalactosamine (GalNAc) ligands
• Using cationic lipids only without targeting moieties
• Formulating liposomes as large multilamellar vesicles (>5 µm)

Correct Answer: Incorporation of galactose or N-acetylgalactosamine (GalNAc) ligands

Q11. During freeze-drying (lyophilization) of liposomal gene formulations, which excipient is primarily used to protect vesicle integrity and nucleic acid activity?

• Sodium chloride
• Sucrose or trehalose as cryoprotectants
• Organic solvents like ethanol
• Polyacrylamide

Correct Answer: Sucrose or trehalose as cryoprotectants

Q12. How does serum protein adsorption (opsonization) typically affect liposomal gene delivery in vivo?

• Enhances endosomal escape directly
• Leads to rapid clearance by phagocytic cells and reduced delivery to target tissue
• Increases circulation half-life
• Prevents interaction with target cell receptors

Correct Answer: Leads to rapid clearance by phagocytic cells and reduced delivery to target tissue

Q13. Which formulation parameter most strongly influences renal filtration and biodistribution of systemically administered liposomal nanoparticles?

• Particle size
• Taste
• Electrical conductivity of buffer
• Presence of cholesterol alone irrespective of size

Correct Answer: Particle size

Q14. What is the main mechanistic reason for using pH-sensitive lipids in liposomal gene delivery?

• To increase thermal stability at 37°C
• To become fusogenic or destabilize membranes at endosomal pH and promote cargo release
• To permanently fix the liposome surface charge
• To inhibit cellular uptake by clathrin-mediated endocytosis

Correct Answer: To become fusogenic or destabilize membranes at endosomal pH and promote cargo release

Q15. Which parameter describes the fraction of total nucleic acid that is successfully encapsulated or associated with liposomes after formulation?

• Polydispersity index (PDI)
• Encapsulation efficiency (EE%)
• Zeta potential
• Hydrophilic-lipophilic balance (HLB)

Correct Answer: Encapsulation efficiency (EE%)

Q16. Reverse-phase evaporation is a method used to prepare liposomes. What advantage does it offer for gene encapsulation?

• Produces large single unilamellar vesicles with high internal aqueous volume, improving encapsulation of hydrophilic nucleic acids
• Eliminates the need for any organic solvents
• Ensures complete PEGylation in a single step
• Automatically sterilizes the formulation

Correct Answer: Produces large single unilamellar vesicles with high internal aqueous volume, improving encapsulation of hydrophilic nucleic acids

Q17. Which in vitro assay best measures functional delivery (biological activity) of delivered siRNA from liposomal formulations?

• Particle size measurement by DLS
• mRNA knockdown measured by qRT-PCR or protein reduction by Western blot
• Thin layer chromatography of lipids
• Zeta potential measurement

Correct Answer: mRNA knockdown measured by qRT-PCR or protein reduction by Western blot

Q18. Which safety concern is particularly associated with permanently cationic liposomes in systemic gene delivery?

• Low transfection efficiency
• Hemolysis, complement activation and higher in vivo toxicity
• Complete resistance to degradation in tissues
• Inability to bind nucleic acids

Correct Answer: Hemolysis, complement activation and higher in vivo toxicity

Q19. What role does cholesterol play in cationic liposome formulations used for gene delivery?

• It acts as a nucleic acid condensing agent by itself
• Modulates membrane fluidity and stability, reducing leakage and improving in vivo performance
• Directly increases endosomal acidification
• Serves as the PEGylating moiety

Correct Answer: Modulates membrane fluidity and stability, reducing leakage and improving in vivo performance

Q20. When scaling up liposomal gene formulations for clinical manufacture, which consideration is most critical to ensure reproducibility?

• Maintaining consistent lipid composition, mixing energy, and particle size distribution across batches
• Changing lipid ratios for each batch to optimize performance
• Eliminating in-process controls to speed production
• Using home-prepared solvents without specification

Correct Answer: Maintaining consistent lipid composition, mixing energy, and particle size distribution across batches

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