(31a) Multifunctional Hydrogel-Coated Gold Nanoshells for Protein Biomarker Quantification

There has been growing interest in using biomarkers expressed in readily available patient samples, such as saliva, tears, urine, or serum, to develop minimally-invasive tests for disease screening and diagnosis. While many different approaches have been explored, differential sensors exploiting arrays of semi-selective recognitive elements are a promising strategy for extending current methods to multiple marker quantification without the need for the development of a new receptor for each biomarker. However, translating differential sensing approaches to protein recognition is challenged by the similarity of the biomarkers’ structures and properties to those of the other proteins present in the sample. In order address this challenge, we explore the capabilities of hydrogel network formation on the surface of gold nanoshells (AuNS) as a semi-selective recognition element for the quantification of protein biomarkers based on differences in polymer functionalization using shifts in the maximum localized surface plasmon resonance (LSPR) wavelength.

AuNS were prepared by seeded growth of colloidal gold on the surface of 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 shells were formed by incorporating the AuNS into the aqueous phase of an inverse emulsion copolymerization of methacrylic acid with acrylamide or n-isopropylacrylamide, crosslinked with N,N’-methylenebis(acrylamide). Transmission electron microscopy was used to determine nanoshell size distribution and UV-Vis spectroscopy was used to measure the shifts in the wavelength of the LSPR. These polymer-coated AuNS can serve as a semi-selective sensor for protein adsorption, which will produce a red shift in the LSPR, and can be modified by incorporating comonomers with selective functionalities or by post-synthesis modification through carbodiimide coupling in order to improve the selectivity of the sensor for certain biomarkers.

Work supported by National Institutes of Health Grant R01-EB022025