Fabrication of Substrate-Independent Protein Microarrays Using Polyelectrolyte Scaffolding

Abstract

While significant advances have been made in regard to protein microarray surface chemistries, the surface modification strategies developed are generally substrate-specific and cannot be interchanged between different materials and platforms. This current lack of substrate-independent surface modification strategies makes it difficult to compare or transfer fabrication methodologies between dissimilar substrates. To address this shortcoming, we have developed an interchangeable surface scaffold, which can be utilized to fabricate protein microarrays on a variety of materials with nearly identical results. The surface scaffold is deposited by alternate electrostatic assembly of the cationic and anionic polyelectrolytes poly(allylamine hydrochloride) and poly(sodium 4-styrenesulfonate), respectively. Once assembled, the polyelectrolyte scaffold serves to mask the underlying surface properties of different materials and convert them to the surface properties of the scaffold itself. By obtaining common surface properties across different materials, it is possible to eliminate differences in protein surface density, spot diameter, and nonspecific binding of analytes on substrates as diverse as glass, gold, mica, silicon, and polymer. The concept of substrate-independent polyelectrolyte scaffolding described here provides researchers with a powerful new tool that can be utilized to compare, optimize, and transfer useful protein microarray surface chemistries across different materials and platforms.

Universal polymer coatings and their representative biomedical applications

“…The properties of the different underlying surfaces were completely converted to the surface properties of the polyelectrolyte coatings. 28 The chemically active scaffold can be further utilized to fabricate protein microarrays. Mouse IgG has been immobilized on PAH-capped polyelectrolyte coatings.…”

“…The nearly identical specific signal intensities of anti-mouse IgG with low nonspecific binding can be observed on the tested dissimilar substrates. 28 LbL assembly is, however, a time-consuming process, especially for the fabrication of thick films. 29 Large dimensional building blocks with fast adsorption kinetics can realize rapid fabrication and have been built with mesoporous silica (MSiO 2 ) nanoparticles with cationic poly(diallyldimethylammonium chloride) (PDDA) to assemble a substrate-independent thick coating with only three coating cycles.…”

Increased Cross-Platform Microarray Data Set Correlation via Substrate-Independent Nanofilms

“…Here, recently developed substrate-independent (SI) nanofilms were investigated as a simple approach to circumvent this limitation by providing a common cross-platform interface. SI nanofilms, which include certain types of chemical vapor deposited (CVD), 14 polyelectrolyte multilayer (PEM), 15 and polydopamine (PD) 16 coatings, represent a unique class of multifunctional thin films (<10 nm) which are capable of depositing onto virtually any material while simultaneously converting their surface properties into those of the nanofilm itself. The resultant film is thick enough to dissociate the surface properties from the underlying material, yet thin enough to minimize interference with bulk properties such as transparency or reflectivity.…”

“…The PEM coating was assembled using a previously reported protocol. 15 Briefly, platforms were immersed in 2 mg/mL PAH in water (pH 7.4) containing 0.1 M sodium chloride for 10 min. Next each platform was washed with five exchanges of water to remove any unbound PAH and dried using a slide centrifuge.…”

“…PAC was utilized in the wash solution as it has been shown to significantly reduce both probe spot streaking and target nonspecific binding during the subsequent sample assay. 15 Blocking was performed by immersing each slide in a solution of PBS containing 2% BSA for 30 min. After the blocking step, each platform was washed with PBST and then water and dried using a slide centrifuge.…”