Optical effects of graphene oxide attached to the hydrogel-inverse opal photonic crystals applicable to rapid semi-quantification of E.coli

Visual readout is one of optical signal responses which are the most widely used in material recognition, providing a simple and fast detection of analytes. In this work, we have studied effects of the attachment of graphene oxide (GO) to the polyethylene glycol diacrylate (PEGDA) inverse opal photonic crystals (IOPC) on the reflection behaviors of the device, aiming at rapid quantification of Escherichia coli (E.coli) by naked eyes. We found a threshold of the concentration of GO (CGO) at which the shift of reflection peak position, λrp, switched from red-shift to blue-shift. This threshold was, thus, related to the optimized CGO for the attachment of GO to the PEGDA-based IOPC. The combination of reflectance spectra and Fourier transform infrared spectroscopies (FT-IR) indicated clearly that with the attachment of GO to the PEGDA-based IOPC, the E.coli antibody DH5-α was maintained on the surface of this device of due to intermolecular interactions, forming hydrogen bonds. In addition, the attachment of GO at the optimized CGO also increased the red-shift of λrp significantly when E.coli was enriched on the surface of the device with the presence of the antibody DH5-α. The photonic color of the device clearly varied from the green color to the red color, corresponding to the concentration of E.coli (CE.coli) increasing from 5 × 102 cfu/mL to 5 × 107 cfu/mL. The sensitivity was estimated to be 408 nm/RIU. These optical behaviors of the modified PEGDA-based IOPC exhibited the potential application of the device like a biosensor for simple and rapid semi-quantification of E.coli in aqueous medium. •Stopband switch of the inverse opal photonic crystals attached with graphene oxide (GO) related to the concentration.•Increase in the stability of the E.coli antibody and widening the red-shift range of the stopband.•Rapid semi-quantification of E.coli through visible photonic color changes for a wide color range.