Chemically Diverse Stimuli-Responsive Polymers for Myriad Applications

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Our group's research program is aimed at solving human health and environmental problems via the development of new advanced functional materials. Our approach to tackling these issues is via the use of stimuli-responsive polymers (SRPs) capable of "sensing" changes in their surroundings and responding in a specified way. The most well-known SRP is poly (N-isopropylacrylamide) (pNIPAm), that exhibits thermoresponsivity, i.e., it shrinks/swells in water at T>32 ºC/T<32 ºC, respectively. Crosslinked pNIPAm-based hydrogel networks with macro/micro/nano scale dimensions (hydrogels, microgels, nanogels, respectively) can be generated and also exhibit thermoresponsivity. This proposal describes the use of pNIPAm-based SRPs, and the diversification of their chemistry, such that new, value added behaviors and properties can be achieved. We envision utilizing these chemically diverse SRPs, and the concomitant diverse responsivities in three main research themes: 1) Sensing and biosensing; 2) Controlled and triggered drug delivery; and 3) Artificial muscles/actuators. The primary goal of Theme 1 is to generate new paradigms for sensing and biosensing by generating a library of pNIPAm-based microgels with various chemistry, such that diverse responsivities can be achieved and sensors developed. The concept relies on microgel-based sensors (etalons) that the group has already developed, but the addition of microgels with such diverse responsivities will lead to great diversity in analytes that we can detect, that we will use in arrays, combined with pattern recognition/machine learning to make sensors for anything. Our first target analyte will be phosphate in natural waters; high phosphate concentrations in natural waters lead to algae blooms and mass fish kills. By continuously monitoring phosphate concentration, conditions that favor algae blooms can be addressed before they become an issue. We will also explore a variety of new sensing schemes utilizing bilayer membranes and antimicrobial peptides. Theme 2 will focus on developing controlled/triggered drug delivery devices with a broad range of triggers and release kinetics/profiles. We will explore the use of chemically distinct thiols on etalons to control release rates, combined with tailoring of the microgel chemistry, to yield release devices with incredible diversity in release profiles. We will also embark on a new research endeavour for the group, by generating microgels that have the ability to trigger macrophage polarization for novel disease treatments. Theme 3 will focus on generating materials capable of triggered actuation and locomotion. These technologies will exploit SRPs as well as shape memory metal alloys to achieve such behaviors. In addition to these well-defined themes, my group will always be looking to discover new materials, and new applications of the materials, to make for a better environment and improved human health.