In situ encapsulation of biologically active ingredients into polymer particles by polymerization in dispersed media

The encapsulation of biologically active ingredients (e.g., peptides, proteins, enzymes, drugs) into polymer particles is extensively used for drug delivery purposes. However, this strategy relies mainly on emulsification processes from preformed polymers, which leads to strong limitations such as low particle concentrations (typically a few wt%), poor active ingredient loadings, as well as a rather limited structural diversity of the polymers usually used. Conversely, polymerizations in dispersed media, which allow for the formation of scalable suspensions of (nano)particles during the polymerization process, have been advantageously used for the in situ encapsulation of active ingredients. In this review, the in situ encapsulation of active ingredients, such as peptides, proteins, enzymes or drugs, in polymer particles obtained by polymerization in dispersed media for potential biomedical applications, is covered. Their physical and chemical encapsulations were both considered as function of the polymerization technique used. Several polymerization and encapsulation parameters will be discussed in view of adjusting the drug loading and the encapsulation efficiency of the active agent considered.