ε-Polylysine and next-generation dendrigraft poly-L-lysine: chemistry, activity, and applications in biopharmaceuticals

Polylysine is an important class of polyamino acids with a broad spectrum of applications in biomedical research and development. It can be divided into two classes, α-polylysine and ε-polylysine, the former is synthesized by artificial chemical synthesis and has limited applications due to its high toxicity, and the latter is produced by microbial synthesis as a class of natural polymers and is widely used in various food, medicinal, and electronics products. Another major class of synthetic polymers is dendrimers (after linear, cross-linked, and branched polymers). Dendrigraft poly-L-lysine (DGL) has the favorable properties of polylysine and dendrimers, with a broad spectrum of applications in drug discovery and development, including drug delivery, gene carriers, diagnostic imaging, diagnostics, biosensors, and special cancer therapies (such as boron neutron capture therapy and photodynamic therapy). As there are still some problems with the development of DGL, further research is warranted for its broad applications.