Jiang Lab
Fundamentals
Molecular-level Understanding and Design
Poly(ethylene glycol) (PEG) is widely used for nonfouling materials, but is unstable for long-term applications. Our group has performed extensive simulation and experimental studies of protein interactions with PEG and zwitterionic groups. From these simulations we have worked out molecular-level nonfouling mechanisms. A set of new zwitterionic and mixed charge materials with unique properties have been designed and developed based on the principles learned.
Development of Zwitterionic Materials
Our group demonstrated for the first time that polysulfobetaine (pSB) and polycarboxybetaine (pCB) are ultra low fouling (< 0.3ng / cm2 adsorbed proteins). Various approaches for attaching these zwitterionic groups onto surfaces and controlling their packing densities/film thicknesses have been explored. These materials are highly effective, stable, and robust.
Development of Mixed Charge Materials
Our group demonstrated for the first time that a wide spectrum of ultra low fouling materials can be prepared from a large number of polymers with positively and negatively charged groups. The advantages of mixed charge nonfouling materials include the simplicity of synthesis, abundance of raw materials, and availability of functional groups. This work opens a new avenue to design new biomaterials. One system of particular interests is ultra low fouling peptides composed of certain positively and negatively charged residuals (e.g., glutamic acid and lysine), which are the first all natural and biologically stealthy materials.
Applications and Impact
Environmentally Benign Marine Coatings
Biofouling on ship hulls and other marine surfaces has become a global environmental and economic issue. Currently, the majority of marine coating products are based on the release of TBT, Cu or biocides. Our group has successfully developed environmentally benign, durable, effective, and low-cost zwitterionic nonfouling coatings. This work is highlighted by an ONR press release.
Biomedical Coatings and Implantable Materials
Our group demonstrated that zwitterionic materials are highly resistant to nonspecific protein adsorption from undiluted blood plasma and serum and have excellent biocompatibility in vivo. We are currently developing implantable autonomous devices and hemostatic/antimicrobial wound dressings for trauma management. In collaborations with Semprus BioSceinces, these materials are being applied to various medical devices.
Nanoparticles for Drug Delivery
Our group is developing highly stable and functionalizable nanoparticles (NPs) for long term circulation in the body for targeted drug/gene delivery and imaging. Merging multifunction and ultra low fouling surface chemistries has been the key to our success in this area. In addition, our results show that undiluted blood serum (instead of 10% blood serum) is needed to evaluate the stability of NPs before their in vivo tests. This work is highlighted by the National Cancer Institute Alliance for Cancer Nanotechnology.
Smart Antimicrobial and Nonfouling Coatings
A switchable polymer surface integrating antimicrobial and non-fouling properties has been developed. The antimicrobial cationic surface can effectively kill bacterial cells and switch to a non-fouling zwitterionic surface, which releases killed microorganisms upon its hydrolysis. This work was highlighted by Science and Nature Biomaterials.
Protein Arrays for Biomarker Discovery and Food Safety
Zwitterionic pCB has not only excellent nonfouling properties, but also abundant functional groups for ligand immobilization. This enables one to create a sensing surface with very low background noise. pCB materials integrated with our$
Biocompatible and Low Friction Materials
The objectives of our work are to understand the molecular origin of friction and to design low-friction materials. Our recent focus has been on the molecular understanding of the relationship between hydration and friction for zwitterionic materials using both molecular simulation and experimental approaches.