Biomaterials and Nanomedicine

Our research focuses on design, synthesis, characterization and evaluation of polymeric and nanostructured biomaterials.  We are particularly interested in developing nanomedicines for their applications in drug delivery to improve or enable medical treatments of human diseases.  Our research covers a broad scope of multidisciplinary areas including chemistry, materials science, nanotechnology, bioengineering and pharmaceutical science.

Development of polymeric nanoparticulate drug delivery systems for cancer therapy

Polymeric nanoparticles are important carriers for the delivery of chemotherapeutics or imaging materials because they can provide prolonged systemic circulation and improved tumor accumulation compared to unformulated drugs.  However, current nanoencapsulates show low drug loadings, uncontrollable encapsulation efficiency and significant drug burst release profiles, all of which significantly limit their potential clinical use.  We aim to develop a new nanofabrication technique that allows facile incorporation of a broad range of therapeutics to degradable polymeric nanoparticles with virtually any drug loading, up to quantitative loading efficiency and drastically reduced burst release of drugs. The new formulation method will allow preparation of multi-therapeutics nanoparticles with core-shell structures to facilitate sequential drug release for potential schedule-dependent, combination cancer treatment.

Organosilicon reagent mediated ring-opening polymerization of α-amino acid N-carboxyanhydrides

Polypeptides are a class of important biomaterials that are extensively utilized in drug delivery, tissue engineering, sensing and catalysis. They are usually prepared through amine initiated ring-opening-polymerizations of α-amino acid-N-carboxyanhydrides (NCAs). Although large-scale, high molecular weight polypeptides can be readily synthesized using this method, the resulting polypeptides typically have uncontrolled molecular weights and broad molecular weight distributions.  We are interested in developing organosilicon reagent mediated controlled NCA polymerization. This method will allow polymerization of NCAs with unprecedented control over molecular weights and molecular weight distributions.

Peptide self-assembly through molecular recognition

The self-assembly of peptide building blocks creates important biomaterials and scaffolds with a wide range of application such as drug delivery vehicles and regenerative tissues. Peptide self assemble is typically achieved via the non-specific interaction, e.g. hydrophobic interaction or hydrogen bonding. We are incorporating molecular recognition to peptide helices in order to precisely and programmably control the assembly of peptides.

Intracellular drug delivery

Cell membranes are natural barriers to many administered macromolecules, such as peptides, proteins and nucleic acids. These molecules enter cells usually through receptor-mediated endocytosis, and are initially localized in the endosomal compartments. A majority of the therapeutics are trafficked to lysosomes and subsequently degraded. There is a significant need for carriers that can enhance the intracellular delivery of agents, in particular to circumvent the barrier of endosomal trafficking. We are interested in designing block copolymer based delivery vehicles with integrated endosomal membrane permeability that can be specifically activated in response to endosomal pH change, resulting in successful trafficking of delivery vehicles with encapsulated agents (e.g. antisense, nucleic acids, and siRNA) from endosomes to cytoplasma.

Synthesis of functional polyesters for drug delivery applications

Polyesters have been widely used in drug delivery, tissue engineering, and biomedical devices. However, polyesters that have been approved for clinical use usually lack side-chain functionalities, resulting in limited variations of their physical and chemical properties via the side chain modification to meet different needs. We are interested in developing coordination initiators for the controlled, living ring-opening polymerization of functional cyclic esters, resulting in homo- or block co-polyesters bearing pendant functional groups (e.g. amino or hydroxyl groups) that can be used for gene and drug delivery applications.