Poly(vinyl alcohol) Rehydratable Photonic Crystal Sensor Materials

Abstract

We developed a new photonic crystal hydrogel material based on the biocompatible polymer poly (vinyl alcohol) (PVA), which can be reversibly dehydrated and rehydrated, without the use of additional fillers, while retaining the diffraction and swelling properties of polymerized crystalline colloidal arrays (PCCA). This chemically modified PVA hydrogel photonic crystal efficiently diffracts light from the embedded crystalline colloidal array. This diffraction optically reports on volume changes occurring in the hydrogel by shifts in the wavelength of the diffracted light. We fabricated a pH sensor, which demonstrates a 350 nm wavelength shift between pH values of 3.3 and 8.5. We have also fabricated a Pb(+2) sensor, in which pendant crown ether groups bind lead ions. Immobilization of the ions within the hydrogel increases the osmotic pressure due to the formation of a Donnan potential, swelling the hydrogel and shifting the observed diffraction in proportion to the concentration of bound ions. The sensing responses of rehydrated PVA pH and Pb(+2) sensors were similar to that before drying. This reversibility of rehydration enables storage of these hydrogel photonic crystal sensors in the dry state, which makes them much more useful for commercial applications.

Tunable Colors in Opals and Inverse Opal Photonic Crystals

“…By using poly(vinyl alcohol) (PVA) as the hydrogel matrix, a pH sensor was obtained that could be reversibly dehydrated and rehydrated while retaining the original diffraction and swelling properties and therefore did not need additives or stabilizers. [ 77 ] A large red shift covering a wavelength range of 350 nm was observed as the pH was raised from 2.6 to 9.1.…”

Photonic crystal borax competitive binding carbohydrate sensing motif

“…These PVA PCCAs have a major advantage over our classic acrylamide PCCAs in their ability to be reversibly dehydrated 15. When rehydrated they show similar sensitivity to that prior to dehydration.…”

“…Synthesis of poly(vinyl alcohol) PCCA was reported previously 15. The PVA was functionalized with glycidyl methacrylate in order to introduce vinyl groups for the PCCA photopolymerization 16.…”

Molecular imprinted opal closest-packing photonic crystals for the detection of trace 17β-estradiol in aqueous solution

“…However, a novel self-reporting sensor platform using the opal closest-packing (OCP) photonic crystal (PC) would be an interesting alternative for easy and rapid detection of the pollutant [11]. The OCP PC is a class of three-dimensional (3D) PC with the continuously ordered 111 plane of the face centered cubic (FCC) lattices and periodic structure, which is different from non-closest-packing polymerized colloidal crystal arrays (PCCA) consisted of highly charged monodisperse polymer spheres [12,13,14], and inverse opal PC (IO PC) composed of a periodically ordered interconnecting porosity-endowed hydrogels [15,16,17,18]. Owing to the Bragg diffraction effect, such PC also exhibits the fascinating Bragg diffraction and bright structural color.…”