Visual in Solution Detection of Denatured Insulin Coupled to Gold Nanoparticles in the Presence of an Aminosilane

Abstract

The pharmaceutical industry is comprised of a myriad of active pharmaceutical ingredients, all applied to increasing human health and quality of life. One of the requirements of reaping the health benefits of these drug products is maintaining them in a native or desired form. Such non-native forms can include, aggregated or fragmented structures. Unfortunately, the most widely used methods to detect non-native or denatured proteins require trained technicians, bulky instrumentation and large amounts of reagents. Deviation from the native structures can occur at all stages; from manufacturing and processing to storage. With these limitations in mind, a simplistic and highly sensitive in solution detection method was evaluated to visually detect denatured insulin proteins, utilizing gold nanoparticle aggregation via 3-Aminopropyltreithoxysilane. The insulin in this study was heat stressed using an 80 • C water bath to create an accelerated heat stressed environment. The insulin, gold nanoparticle and aminosilane solution was then characterized utilizing, UV-Vis spectroscopy, dynamic light scattering and scanning electron microscopy. Captured images and resulting absorbance spectra of the trials demonstrated visual color changes detectable with the human eye as a function of the denaturation time. This work serves as an extended proof of concept for fast in solution detection methods for proteins that have experienced heat stress.