Inorganic-Organic Thin-Layers which Transform Bio-Molecule Binding into Visible Color Change

Abstract

SiO2 thin-films were prepared by thermal oxidation method. It showed uniform color based on the thin-film interference of visible light. Then we made biotin antenna on the top of SiO2 thin-film. Biotin is one of the vitamins and it has high association constant with protein avidin. After immersed the substrate into avidin solution, certain color changes based on the self-assembling of avidin on its surface were observed. By the immersing these substrates into mono-dispersed polystyrene particle solution, a polystyrene particle layer was formed onto avidin SAMs and it brought dynamic interference color change. As a result, this substrate could sense the avidin molecules over 1.0×10-8M of its concentration by naked eyes.

Visible detection of biotin by thin-film interference: thickness control through exchange reaction of biotin/dethiobiotin–avidin bonding

“…Previously, we have demonstrated that a silica thin-film constructed on a silicon substrate showed interference color change when bacteria and protein adsorbed on it. [13][14][15][16] Adsorption of bacteria of a sub-micron scale gave a visible color change, which was not only observed by spectrum measurement, but was also seen by the naked eye. On the other hand, adsorption of small molecules on the nanometre scale, such as antigens and peptides, gave little color change, which was only observed by spectrum measurement.…”

Design and Fabrication of Biosensor for a Specific Microbe by Silicon-Based Interference Color System

“…In fact, we can calculate the whole thickness of the external layer including the layers of oxide (SiO 2 ), organic layers, and microbe. Strong shifts in optical properties were similarly observed when increasing the thickness by the addition of nanolayers [ 3 ], chemical vapor absorption [ 6 , 32 ], and an aqueous dispersion of microgel [ 33 ].…”

“…However, colorimetric detection systems have a fundamental problem detecting specific molecular interactions, such as antibodies or nucleic acids. At the same time, the advantage of the optical platform is that the unaided eye can detect changes in the iridescent color due to several factors such as the nano-ordered film thickness, the number of layers, and the angle of the incident light [ 3 , 4 , 5 , 6 , 7 ]. The chip presented herein is developed especially for the detection of a specific pathogen, Sphingobium yanoikuyae [ 8 , 9 ], which alters the taste of non-beverage alcohols.…”

“…Since those sensors have limited diagnostic ability, they require instrumentation for signal detection [ 18 ]. We have worked for several years on silicon-based iridescent color chips through the coating of various numbers of peptide layers [ 3 , 5 , 6 ]. In this study, we have investigated the application of different numbers of nano-ordered layers of different biomaterials through a step-by-step surface-modification strategy, which provides considerable flexibility in the formation of an iridescent color response for visual sensor applications.…”