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Professor Mary Chan-Park’s main research
interests are in polymers in nanoscience and biotechnology, and she has
published extensively, with more than 280 papers in top-tier journals. (1)
Antimicrobial
POLYMERS The emergence of microbial resistance to antibiotics is a serious and growing challenge for human public health. There is an overwhelming demand for new antimicrobial materials that are not vulnerable to the development of microbial resistance and which are also non-toxic and biocompatible. Contact active antimicrobial materials, such as positively charged (cationic) polymers, kill bacteria by disrupting their membranes rather than targeting microbe metabolism and consequently are believed to be less likely to lead to resistant bacteria. Dr Chan’s group has developed a novel class of antimicrobial materials based on positively charged “sugar” polymers. Most cationic polymers are non-selectively toxic so that they kill microbes but also mammalian cells. Her “sugar-based” cationic polymers are highly selective for microbes and have record high selectivity. Further, she has designed new biomedical coatings based on nanoporous hydrogels which are highly effective to kill microbes. Most antimicrobial coatings are non-porous solids, and the polymers significantly lose antibacterial efficacy when immobilized. The hydrogel coatings, on the other hand, have interior space to “receive” the disrupted mammalian cell membranes and have excellent antimicrobial efficacy. Their findings have recently been published in Nature Materials, Advanced Materials and Biomaterials. Her discovery of a new contact-active mechanism for killing microbes forms the basis for the design and synthesis of a wide range of polycationic antimicrobial materials for diverse applications, ranging from biomedical implants to paints and other surface coatings for aseptic environment in medical facilities. (2)
Delivery of RNA and
other drugs via polymeric carriers for Endosomal Escape and Targeted Delivery Dr Chan has
also investigated the application of polymers in drug and RNA delivery. Ribonucleic
acid (RNA) therapeutics, which are nucleic acid fragments with defined
sequences that interfere with specific gene expression or produce therapeutic
proteins, are promising medicines, as shown by the recent success with COVID
vaccines. They can treat or prevent a multitude of human diseases ranging
from infectious diseases to cancers to genetic disorders. However, RNAs are
generally large hydrophilic polyanions that cannot enter cells on their own.
In addition, naked RNAs are vulnerable to removal by the immune system and by
RNases in tissues. Hence, they require suitable delivery vehicles to reach
the cytosol, which is the target site of RNA therapeutics. Various families
of delivery vehicles have been explored. Among them, lipid nanoparticles (LNPs),
which are employed in the recent FDA-approved COVID-19 mRNA-LNP vaccines, are
one of the most advanced systems. There are now at least 15 FDA-approved RNA
therapeutics, including two COVID-19 mRNA vaccines, with another 15 or more
approvals expected in the next 5 years. Besides LNPs, polymeric nanoparticles
are also commonly researched. However, when RNA Delivery Vehicles enter
cells, most of the particles are entrapped in some sub-cellular compartments
such as endosomes and are finally destroyed. Only a small fraction of the
particles reaches the final target in the cytosol. To reduce toxicity and
improve the treatment outcome, a critical hurdle is to improve the endosomal
escape efficiency of delivery nanoparticles. Our group works on the development
of carriers with improved endosomal escape efficiency. Dr Chan is an elected fellow of the American Institute of Medical and Biomedical Engineering. She is also on the Editorial Board of three international and highly reputed journals: (i) Journal of Biomedical Materials Research: Part A (ii) American Chemical Society Applied Materials and Interfaces and (iii) Polymers for Advanced Technologies. She has published extensively in top tier journals such as Nature Materials, Advanced Materials, Advanced Functional Materials, Small, Biomaterials, etc. Her work in the past 10 years has garnered total citations of more than 20,000 and led to about 20 patents/patent applications. Dr Mary Chan obtained her B.Eng (Chem) and PH.D from the National University of Singapore and MIT in 1986 and 1993 respectively. Prior to joining NTU in 2001, she worked in the chemical industry. She was formerly a senior technical manager in Sipix Imaging (CA, USA) working on Epaper development. |