Polycarbonates for delivery of drugs and methods of preparation thereof

An amphiphilic block copolymer, comprising:

• a hydrophilic poly(alkylene oxide) block;
• and
• a biodegradable hydrophobic block comprising a first repeat unit of formula (3):
• wherein i) t and t′ are integers independently having a value of 0 to 6 wherein t′ and t cannot both be zero, ii) each Q1 is a monovalent radical independently selected from the group consisting of hydrogen, halides, alkyl groups comprising 1 to 30 carbons, and aryl groups comprising 6 to 30 carbon atoms, iii) L′ is a divalent linking group comprising one or more carbons, iv) S′ is a steroidal group.

A loaded micelle comprising:

• 85.0 wt. % to 99.9 wt. % of the amphiphilic block copolymer comprising a) a hydrophilic poly(alkylene oxide) block and b) a biodegradable hydrophobic block comprising a carbonate repeat unit of formula (3):
• wherein i) t and t′ are integers independently having a value from 0 to 6 wherein t′ and t cannot both be zero, ii) each Q1 is a monovalent radical independently selected from the group consisting of hydrogen, halides, alkyl groups comprising 1 to 30 carbons, and aryl groups comprising 6 to 30 carbon atoms, iii) L′ is a divalent linking group comprising one or more carbons, and iv) S′ is a steroidal group;
• and
• 15 wt. % to 0.1 wt. % of a biologically active cargo material bound by non-covalent interactions to the block copolymer, wherein weight percent (wt. %) is based on total dry weight of the loaded micelle.

A method, comprising:

• forming a solution comprising a water miscible organic solvent, a biologically active substance, and an amphiphilic block copolymer, the block copolymer comprising a) a hydrophilic poly(alkylene oxide) block and b) a biodegradable hydrophobic block comprising a carbonate repeat unit of formula (3):
• wherein i) t and t′ are integers independently having a value from 0 to 6 wherein t′ and t cannot both be zero, ii) each Q1 is a monovalent radical independently selected from the group consisting of hydrogen, halides, alkyl groups comprising 1 to 30 carbons, and aryl groups comprising 6 to 30 carbon atoms, iii) L′ is a divalent linking group comprising one or more carbons, and iv) S′ is a steroidal group;
• and
• dialyzing the solution against water using a dialysis membrane system, thereby forming a loaded micelle comprising the block copolymer bound by non-covalent interactions to the biologically active material.