Sensing Elements Encapsulated within Hydrogel Matrix to Enhance the Signal-To-Noise Ratio

Abstract

In this study, we developed polydiacetylene(PDA) vesicle based colorimetric biosensor. PDA vesicle is a cluster of diacetylene(DA) lipid that has a unique property of color transition from blue-to-red upon eternal stimuli, such as temperature, pH, and mechanical stress. In our biosensor, PDA vesicle was conjugated with target-specific antibody by EDC/NHS coupled reaction to identify target protein. Antibody conjugated PDA vesicle was then encapsulated into Poly(ethylene glycol) diacrylate(PEG-DA) hydrogel at high density to enhance reaction sensitivity. Furthermore, PDA vesicle encapsulating hydrogel was formed in spherical shape by using droplet-microfluidic device to enable transportation. We named this colorimetric biosensor as immunohydrogel bead. Detection of PAT protein from genetically modified organisms (GMO) was attempted for practical use. The PAT protein allows herbicide resistance to GMO and was known as model protein of GMO. Using immunohydrogel bead, PAT protein was detected to 20 nM with naked eyes which means that even 1% of GMO can be detected. Thus, we expect that immunohydrogel bead can be used practically not only in GMO but also in other targets.