Physically or chemically cross-linked hydrogel particles made of stimuli-responsive smart polymers have attracted considerable attention in recent years. Nanoscale sized hydrogel particles dispersed in aqueous medium or ‘nanogels’ are soft nanomaterials that can be applied to a diverse field of interests, ranging from drug delivery, biosensors, protein and biomolecule separation and purification. Stimuli-responsive nanogels respond to the changes of environmental factors, such as pH, temperature, and ionic strength by changing size and surface morphology. Nanogels of poly(N-isopropylacrylamide) (PNIPAM) polymer material show characteristic reversible phase transition from a swollen hydrophilic state at a lower temperature to a hydrophobic collapsed state at a higher temperature. The swelling-deswelling property of nanogels has been exploited in drug delivery applications and chromatographic separation of biomolecules. However, a molecular level understanding of the specific interactions between nanogel particles and biomolecules, such as proteins, is lacking.<br/>Fluorescence based single-molecule microscopy and single particle tracking methods are ideal to understand the complex dynamic behavior of proteins at the polymer surface. In this study, the dynamics of a model protein lysozyme on the nanogel surface and inside the nanogel cavity were investigated using single molecule spectroscopy. Understanding these complex surface and intra-cavity dynamics of biomolecules will instigate further theoretical and experimental studies of these systems. This will inspire better bottom-up design strategies with other stimuli-responsive polymers for various applications including, but not limited to, separation science and biomedical sciences.

Protein dynamics on the stimuli-responsive nanogel surface and inside nano-cavities

256th National Meeting (2018)

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