6.2.1.2　Poly（amino acids）

Poly（amino acids）contain multiple reactive sites，therefore，it is easy to manipulate their hydrophilicity，charge and targeted features through further modification.Poly（glutamic acid），polylysine，poly（styrene alanine）and poly（aspartic acid），etc.are commonly used for nano-drug carriers.Hydrophobic poly（amino acids）usually link with hydrophilic polymer block（such as poly（ethylene glycol））forming amphiphilic block copolymer to prepare micelles，which can be used as nano-drug carriers.With the active groups such as carboxyl and amino groups，poly（amino acids）are capable of combining with drug molecules through either chemical bonding，physical embedding，or electrostatic adsorption.Therefore，the drugs can be loaded in different positions of the micelles.Amino acid copolymers can be synthesized by copolymerization of two or more amino acids.Due to their rich variety，amino acids with the desired structure and properties can be selected to prepare copolymers according to the requirements of different drugs.(https://www.daowen.com)