Label-free quantification of polymerization is of significant importance in today's research as recent advancements in the polymer field have sparked numerous applications in the biomedical industry. Poly-((Ethylene Glycol) Methyl Ether)- Methacrylate (POEGMA) has been recognized as a replacement for PNIPAM for biomedical applications due to various factors such as biocompatibility and thermal response rate. With a rapid thermal response, POEGMA allows for a variety of biomedical applications including a potential drug delivery mechanism. In this study, a Photonic Crystal-Total Internal Reflection (PC-TIR) biosensor has been utilized to monitor POEGMA-144, which has been synthesized via an Atom Transfer Radical Polymerization (ATRP) grafting-from approach. Monitoring the optical resonance of this biosensor, it allows for quantification of the growth of a layer of an initiator on the sensor surface as well as the growth of the POEGMA on top of it. In addition, the PC-TIR sensor further allows real-time analysis of the polymer’s thermal responsiveness in an aqueous environment. At a well-defined, molecular weight specific, Lower Critical Solution Temperature (LCST) of 42°C, the POEGMA-144 polymer conformationally changes, becoming hydrophobic and collapsing after expelling any water between its PEG side chains. Using the PC-TIR biosensor, a definitive polymer collapse was observed at the LCST; similarly, a re-swelling of the polymer was observed as the ambient temperature of the polymer was allowed to cool back to room temperature.
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