Human health conditions can be improved by developing new DNA delivery approaches for controlling and treating diseases. Fundamental goal in this area of research is the safe and efficient transfer of foreign DNA into cells. Cationic polymers can be used as non-viral delivery vehicles in this regard. Cationic polymers can form complexes with DNA, termed polyplexes which are compact nanoparticles. They can protect DNA from enzymatic degradation and deliver the cargo into the cell nucleus. My current projects involve the design of novel polymers that can self assemble into micelles and polymersomes for the delivery of DNA.
Chemicals from Biomass
Hydrocarbon-rich biomass such as pine chemicals, plant oils, fatty acids, terpenes and terpenoids are increasingly recognized as feedstock chemicals to replace fossil chemicals. These natural products provide hydrophobicity that is comparable to many petroleum chemicals such as ethylene and styrene. This property is useful for various applications such as food packaging and biomedical application. While this class of biomass bears numerous constitutional isomers, we have executed organic functionalization and successfully derivatized many of them into a series of monomers that can undergo controlled and living polymerization such as ATRP, RAFT, ROP and ROMP to yield a variety of macromolecular architectures. We have combined biodegradable skeleton with biomass that exhibit much better hydrophobicity than emerging polyesters such as poly(lactic acid) and polycaprolactone. Our experiments have opened novel pathways to utilize these natural biomass to produce sustainable polymeric materials with improved mechanical properties.
Cationic Antimicrobial Polymers
Natural product derived cationic compounds and polymers can be used as very effective antimicrobial materials to kill both Gram-positive and Gram-negative bacteria while maintaining low cytotoxicity to mammalian cells. We carry out molecular dynamics simulation (with collaborations) and model experiments to investigate interactions between antimicrobial agents and cell membranes and hope to reveal killing mechanisms.
We have found out that cationic metallopolymers such as cationic cobaltocenium-containing polymers can form unique ion-pairs with conventional antibiotics. The novel materials protect the antibiotics from β-lactamase enzymes and greatly improve the efficacy against a wide range of bacteria. Currently, we are exploring new derivatives of these materials for biomedical applications.