Fluorescence Signal Enhancement by a Spray-Assisted Layer-by-Layer Technique on Aluminum Tape Devices for Biosensing Applications

Abstract

Layer-by-layer (LbL) self-assembled polyelectrolyte multilayer (PEM) films are a simple yet elegant bottom-up technology to create films at the nano−microscale. This low-cost technology has been widely used as a universal functionalization technique on a broad spectrum of substrates. Biomolecules under investigation can be incubated onto films based on complementary charge interactions between the films and biomolecules. There is a great demand for developing an ultralow-cost biosensing device, which can optimally enhance the fluorescence signal of the adsorbed biomolecules from the traditional labeled sensing platforms. In this work, we have incorporated a blend of the conventional metal enhanced fluorescence technology and the PEM as a dielectric spacer and functionalized film, coated on an aluminum paper (tape)-based substrate. These device has been found to be capable of holding biomolecules in three-dimensional PEM space. The devices fabricated by the proposed spray LbL technique provide significant fluorescence signal enhancement by holding a relatively higher mass per volume of the adsorbed biomolecules, when compared to traditional spin-and dip-coating techniques. Interestingly, our proposed device has expressed a fluorescence enhancement factor, which is 9 times higher than PEM-functionalized glass-based devices. To demonstrate the practical utility of our devices, we also compared our devices to Whatman FAST slides. Our experimental fluorescence results are almost comparable to Whatman FAST slides. Such PEM devices fabricated on top of low-cost aluminum tape using a spray LbL technique give new insights into the future development of ultralow-cost, high-throughput, and disposable lab-on-chip diagnostic applications.

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

“…[ 66 ] In our previous investigations, for enhancing fluorescence signals, distance‐dependent metal enhanced fluorescence techniques were implemented on aluminum tape using PEM as a dielectric spacer. [ 67 ] It was concluded that FDip devices showed better bio‐adsorption performance than spin‐coated devices. Therefore, devices fabricated by FDip‐LbL offer a wide range in designing the biosensors with minimum deposition time compared to devices fabricated using spin‐based LbL self‐assembly.…”

Nanoarchitectonics for Free‐Standing Polyelectrolyte Multilayers Films: Exploring the Flipped Surfaces

“…[168,169] The flexibility of LbL techniques for depositing FS-PEM and the inclusion of a wide variety of polymers, biomolecules, and inorganic and graphene-based 2D materials make them promising sensing platforms for numerous applications. [170][171][172][173][174][175][176] Transparent FS-PEM holographic films of (PDDAC/Heparin) impregnated with cobalt (II) chloride have been used as a quantitative tool for measuring environmental humidity. [173] Inspired by PEM-based assembly, hybrid inorganic NPs assembled freestanding nanoarchitectures have been utilized for surfaceenhanced Raman scattering (SERS)-based bacterial detection.…”

“…Still, PEM layering is known to upgrade microfluidics‐based platforms by providing barrier safety against the flowing organic components [168,169] . The flexibility of LbL techniques for depositing FS‐PEM and the inclusion of a wide variety of polymers, biomolecules, and inorganic and graphene‐based 2D materials make them promising sensing platforms for numerous applications [170–176] . Transparent FS‐PEM holographic films of (PDDAC/Heparin) impregnated with cobalt (II) chloride have been used as a quantitative tool for measuring environmental humidity [173] .…”