TABLE 8.

Advantages and limitations of different surface modification techniques.

Method	Advantage	Limitation
Coextrusion	High degree of control reproducibility	Clogging
	Preserves orientation of the vesicle	Exosomes prone to aggregate after extrusion
		Preformed vesicles are required
Sonication	Applicable to both micron- and nanosized biomaterials	Low yield of fully coated particles
	High throughput
	Less loss of material
Adsorption	Simple	Unstable
	Applicable to both micron- and nanosized biomaterials	Possibility of non-specific interactions
		May require a preconditioned surface
Chemical conjugation	High control over degree of surface modification	Possible denaturing effects
	Applicable to both micron- and nanosized biomaterials
Pickering emulsion	Simple and fast	Less control over stability
	Preserves dynamic nature of emulsion droplets	High requirement in optimizing mass ratio of cores and coating materials
Electroporation	Simple and fast	Possible low encapsulation yield
		Preformed vesicles are required
Passive loading	Simple	Suitable for NPs
	Non-invasive	Preformed vesicles are required
Freeze-thawing	Preserves integrity, structure, and composition of biological membranes	Suitable for NPs
		Changes the orientation of the coating vesicle
Coprecipitation	Easy scale-up	Harsh chemical process
	Allows control over the particle size	Not suitable for biological membranes
Emulsion evaporation	High encapsulation yield	Less control over polydispersity
	Applicable for both hydrophobic and hydrophilic particles	Requires organic solvents
	No size restrictions
Coaxial electrospray	No restrictions in hydrophilicity or hydrophobicity of adjacent layers	Low throughput
Electrostatic deposition	Uniform coating	May require a preconditioned surface
		Expensive
Microfluidics-assisted techniques	Allow precise control	Require large number of auxiliary equipment
	High degree of coating by improved mixing	Expensive
		Clogging