Over the past 30 years many groups have been interested in microgels and nanogels, particularly colloidal aqueous hydrogels that respond to their environment (temperature, pH, etc). We have two very specific interests in these types of materials. The first is as reference beads for mass cytometry, a high throughput bioanalytical technique based on atomic mass spectrometry for determining biomarker expression on cells. Microbeads containing known amounts of lanthanide (Ln) ions allow the instrument to be calibrated in situ. Initially we prepared poly(N-isopropyl acrylamide-co-vinyl caprolactam-co-methacrylic acid) microgels loaded with precipitated LnF3. Unfortunately, the Ln ions slowly leached from the microgels at mildly acid pH. Using these microgels as reactors to generate the less soluble LnPO4 nanocrystals was a challenge that makes a very interesting story. The second area of interest to us is the use of colloidal hydrogels as covalent hosts for enzymes for reactions to be carried out at elevated temperatures. The thermally induced collapse transition of common aqueous microgels normally interferes with enzyme activity. We designed and synthesized a functional poly(hydroxyethyl acrylamide) microgel, a thermally unresponsive microgel (no cloud point for T ≤ 140°C). We attached the enzyme horseradish peroxidase (HRP) to the microgel, and, for comparison, also attached HRP to PEGMA microgels, which have a collapse transition in water at about 55 °C. We studied the activity of HRP on both microgels at temperatures up to70 °C.

Aqueous microgels as reference beads for mass cytometry and supports for enzyme reactions at elevated temperatures

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.