Nanogels with particle sizes ranging from 1 to 1000 nm have attracted worldwide attention due to their potential applications in drug delivery

medical diagnosis

biosensor

bioseparation

etc. This review describes the research progress of nanogels synthesizing methods based on their raw materials

including polymerization of monomers with crosslinkers and post-crosslinking of polymers. The former can be categorized into three kinds of methods:precipitation polymerization

inverse emulsion polymerization and micromold polymerization. The latter can be classified into four kinds of methods:precipitation/crosslinking

emulsion/crosslinking

micromolding/crosslinking and self-assembly/crosslinking. Furthermore

the advantages and disadvantages of these methods are reviewed

and some viewpoints on synthesizing the nanogels for biomedical applications are put forward.