Enhanced Multicolor Resonant-Optical-Assay with Direct Text Output

The effectiveness of a novel multicolor biochip boosted by reducing cluster repulsion and in-situ silver enhancement has been demonstrated by using anti-serum albumine antibodies conjugated to gold nanoparticles on a vacuum metalized plastic film coated with nano-resonance driving ceramic multilayers. A dense and smooth vacuum deposited SiO similar to 1.6 top layer (50 to 300 nm thick) on a flexible thermoplastic polymer poly-ethylene-terephthalate-chip functionalized via poly-ethylenimine monolayer coating and chemical cross-linking was employed to immobilize capture antibodies. Following capturing of the human serum albumin antigen from analyte solution, the multicolor chip reacts with anti HSA-gold nanoparticles binding them in a nanometric distance to the resonant mirror of the device-visible to the eye as faint coloring of the chip surface. Following silver enhancement, a strong metallic angle-dependent color via Resonance Enhanced Absorption is observed. In this study, silver staining has been used for the first time to boost and shift the color of nano-resonance enhanced optical bioassays. The use of silver staining increases and significantly modifies the intensity of the resonance color and was done in less than 5 minutes directly on the chip. This novel methodology will find broad application in Point-of-Care diagnostic devices via a color signal output designed as a written text with high contrast to replace standard lateral flow devices just showing lines or dots.