RESUMO
Improving the performance of traditional diagnostic lateral flow assays combined with new manufacturing technologies is a primary goal in the research and development plans of diagnostic companies. Taking into consideration the components of lateral flow diagnostic test kits; innovation can include modification of labels, materials and device design. In recent years, Resonance-Enhanced Absorption (REA) of metal nano-particles has shown excellent applicability in bio-sensing for the detection of a variety of bio-molecular binding interactions. In a novel approach, we have now integrated REA-assays in a diagnostic microfluidic setup thus resolving the bottleneck of long incubation times inherent in previously existing REA-assays and simultaneously integrated automated fabrication techniques for diagnostics manufacture. Due to the roller-coating based technology and chemical resistance, we used PET-co-polyester as a substrate and a CO(2) laser ablation system as a fast, highly precise and contactless alternative to classical micro-milling. It was possible to detect biological binding within three minutes - visible to the eye as colored text readout within the REA-fluidic device. A two-minute in-situ silver enhancement was able to enhance the resonant color additionally, if required.
RESUMO
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 approximately 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.