(22d) Inverse Emulsion Synthesis of Hydrogel-Coated Gold Nanoshells for Protein Biomarker Quantification

As proteomics research has begun to identify increasing numbers of differences in the protein makeup of patient samples, such as saliva, tears, urine, or serum, between healthy and diseased patients, there has been growing interest in developing new biosensor diagnostic tools that allow for minimally-invasive quantification of these potential biomarkers. One strategy is differential sensor arrays that exploit semi-selective recognitive elements in order to screen for differences in multiple protein biomarkers in a single assay. However, accurate protein recognition is challenged by the similarity of the target protein’s structures and properties to those of the other proteins present in the sample, necessitating the use of multiple sensing elements in order to separate the interactions. In order address this challenge, 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 autoimmune disease biomarkers.

Hydrogel nanoparticles were formed by an inverse emulsion copolymerization of methyacrylic acid with acrylamide or N-isopropylacrylamide, crosslinked with N,N’-methylenebis(acrylamide), and 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 using the same nanoparticle synthesis method 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. The successful synthesis of coated AuNS with both formulations 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 biofluids.

Work supported by National Institutes of Health Grant R01-EB022025