Varying polymer architecture to deliver drugs.

Variable architecture polymers are of considerable interest for the delivery of therapeutic biopolymers, such as DNA and proteins, to their site of action. Polymers that can respond with a change in conformation to biologically relevant stimuli, such as temperature and pH, are being carefully designed to take advantage of the change in environmental conditions the polymer-drug conjugate encounters upon progression from larger-scale systems in the body to subcellular compartments. Viruses respond to changes in the cellular environment to gain access to their desired region of cells, and much can be learned from the mechanisms they employ in this effort. However, despite the efficiency of therapeutic biopolymers, undesirable immune and inflammatory responses may result from their repeated administration, so synthetic polymers are an attractive alternative. This mini-review examines a range of recently developed variable architecture polymers, mainly focusing on polymers responsive to temperature and pH, covering both synthetic copolymers and derivatives of naturally occurring polymers for advanced drug delivery applications. The polymers discussed in the article have some of the properties that are most important for polymer drug delivery vehicles to be effective, such as biodegradability, specificity, and biocompatibility.