Table 1 Comparative evaluation of various methods for the MDS preparation

1

Liquid–liquid suspension polymerization

It may be adjusted to a single-step or two-step technique for drug loading

(a) Solvent traces and unreacted monomers can be trapped; (b) the structure is non-uniform; (c) the reaction time needed for monomers is considerable; and (d) thermosensitive medicines necessitate two-step methods

[6, 19]

2

Quasi-emulsion solvent diffusion

High drug loading, no monomer entrapment, low solvent traces, MDS size is readily regulated by regulating the stirring rate, and spherical microsponges are obtained

(a) Not appropriate for loading water-soluble medicines, and (b) the monomer reaction takes a long time

[6, 19]

3

Multiple-emulsion solvent diffusion

(a) Water-soluble drugs can be loaded effectively, and (b) proteins and peptides may be entrapped using this approach

Requires the use of water-insoluble surfactants, which can be found in the form of residues in the resultant MDS

[6, 19]

4

Addition of porogen

Extremely porous structure with well-distributed and interconnected pores

Disruption in structure may occur

[6, 19]

5

Lyophilization

Method is simple and quick, and the results are repeatable

To get rid of the organic solvent remnants, vigorous washing is required

[6, 19]

6

Ultrasound-assisted production

No solvent traces, produce rapid and reproducible results

It is possible that an irregular structure may emerge, necessitating the use of cross-linking chemicals, which may be harmful

[6, 19]