(210d) Hydrogel-Encapsulated Gold Nanoshells Prepared By Inverse Emulsion Polymerization As a Biosensor for Sjögren’s Syndrome Protein Markers

Proteomics research has led to identification of increasing numbers of differences in the protein makeup of biological fluids, such as saliva, tears, urine, or serum, due to the onset of disease; however, more work is needed to improve the molecular recognition capabilities of existing biosensors before these markers can see more widespread adoption in clinical practice. One approach for more robust, low-cost recognition elements is synthetic receptors based on polymeric hydrogels, but this approach is challenged by the lack of specificity toward the target analytes, which reduces their viability for recognition in biological fluids due to a myriad of competing molecules. One solution is differential sensor arrays that exploit semi-selective recognitive elements in order to screen for differences in multiple protein biomarkers in a single assay. In this work, we explore the capabilities of using inverse emulsion polymerization to form libraries of multifunctional hydrogel networks on the surface of gold nanoshells (AuNS) as semi-selective recognition elements for use in a localized surface plasmon resonance-based biosensor for the detection of biomarkers associated with Sjögren’s syndrome.

Hydrogel nanoparticles were prepared by an inverse emulsion copolymerization of methacrylic acid with acrylamide or N-isopropylacrylamide, crosslinked with N,N’-methylene bisacrylamide. The particles were characterized by dynamic light scattering, potentiometric titration, and Fourier-transform infrared spectroscopy. AuNS were prepared using the method of seeded growth of gold colloids on aminated silica nanoparticles followed by encapsulation with poly(maleic anhydride-alt-1-octadecene)-g-poly(ethylene glycol) methacrylate (PMAO-g-PEGMA) graft copolymer to improve particle stability. Hydrogel-coated AuNS were prepared with the same procedure as the nanoparticle synthesis with the addition of PMAO-g-PEGMA AuNS to the aqueous phase of the inverse emulsion. UV-Vis spectroscopy was used to measure the shifts in the wavelength of the localized surface plasmon resonance for the hydrogel-coated AuNS. Inverse emulsion synthesis was found to lead to thin surface coatings for both formulations and shows immense promise for the creation of a library of hydrogels with various functional groups that could be used to alter affinity for different protein biomarkers from patient biological fluids.

Work supported by National Institutes of Health Grant R01-EB022025