Fast-Dip Layer-by-Layer Self-Assembly of Polyelectrolytes as a Low-Cost Biosensing Platform

Polyelectrolyte multilayer (PEM) films fabricated using Layer-by-Layer (LbL) self-assembly are most versatile for numerous surface tailoring applications. Physicochemical customization of PEM at a nanometer scale is possible by choice of incorporated materials, assembly parameters, and assembly techniques. Conventional dip (CDip) (10–15 min dip time) coating dominates the PEM fabrication due to its simple, geometry-independent, and economical coating capabilities. Deposition of the PEM in CDip-LbL happens in two phases, that is, the initial adsorption phase followed by rearrangement of the complementary polyelectrolyte chains. By shortening the prolonged rearrangement phase, thicker stratified PEM films can form with a reduced dipping time (1 min), called Fast Dip (FDip). This reduction in the dipping time is studied in situ using Etched Fiber Bragg Grating-based sensors. To define the practical utility of the FDip deposited PEM, bio-molecular loading studies are performed using biotin and Bovine Serum Albumin (BSA). FDip-LbL is as effective as CDip-LbL self-assembly and also better than spin-LbL. Thus, the FDip deposition prompts a scalable LbL self-assembly process for quick fabrication of the biosensing platforms.