Intelligent Polymerized Crystalline Colloidal Arrays:  Novel Chemical Sensor Materials

Abstract

We report the development of a novel sensing material that reports on analyte concentrations via diffraction of visible light from a polymerized crystalline colloidal array (PCCA). The PCCA is a mesoscopically periodic crystalline colloidal array (CCA) of spherical polystyrene colloids polymerized within a thin, intelligent polymer hydrogel film. CCAs are brightly colored, and they efficiently diffract visible light meeting the Bragg condition. The intelligent hydrogel incorporates chemical molecular recognition agents that cause the gel to swell in response to the concentration of particular analytes; the gel volume is a function of the analyte concentration. The color diffracted from the hydrogel film is, thus, a function of analyte concentration: the swelling of the gel changes the periodicity of the CCA, which results in a shift in the diffracted wavelength. We have fabricated a sensor, utilizing a crown ether as the recognition agent, that detects Pb 2+ in the 0.1 µM-20mM (∼20 ppb-∼4000 ppm) concenration range. We have also fabricated glucose and galactose sensors, utilizing glucose oxidase or β-D-galactosidase as the recognition elements. The glucose oxidase sensor detects glucose in the 0.1-0.5 mM (18-90 ppm) concentration range in the presence of oxygen and detects as little as 10 -12 M glucose (0.18 ppt) in the absence of oxygen. In addition, this sensor reports on dissolved oxygen concentration from ∼1 to 6 ppm in the presence of constant glucose concentrations.

Photonic-crystal full-colour displays

“…As would be expected from a polymer-network-based PC composite [10][11][12][13][14][15] , P-Ink films show colour changes based on solvent swelling. Solvent influx into the network causes a lattice increase, and is manifested as a redshift of the Bragg diffraction peak.…”

Transport of Ions and Electrostatic Interactions in Thermoresponsive Poly(N-Isopropylacrylamide-co-acrylic acid) Hydrogels: Electroanalytical Studies

“…This decrease in concentration depends on the composition of the gel; it is more significant for higher percentages of NIPA-AA polymer in the gel, and it depends on the ionic strength of the systems, changes are more pronounced in gels without electrolyte than in those of high ionic strength. 4%NIPA-AA gel 5.8xl0 6 16. T(°C) Figure 5 …”

“…The number of applications of stimuli-responsive polymeric gels increases continuously [5]. In addition to medical and biotechnological applications [1], phase transition phenomenon might be very important for gel-based chemical sensors [6] and as electrolytes for batteries and other power sources.…”

“…ABSTRACT . To study transport phenomena and electrostatic interactions m negatively charged poly(Nisopropylacrylacrylamide-co-acrylic acid) hydrogels, NIPA-AA, electroanalytical experiments with two positively charged probes, ferrocenylmethyltrimethylammonium, FcTMA , and hexaammineruthenium(III) Ru(NH 3 ) 6 3+ cations were performed, and the results compared with those for an uncharged electroactive probe, 1 l'-ferrocenedimethanol, Fc(MeOH) 2 . Steady-state voltammetry and chronoamperometry at platinum disk rnicroelectrodes were used to determine diffusion coefficients of those probes.…”

Osmotic-pressure-controlled concentration of colloidal particles in thin-shelled capsules

“…Such dynamic control is especially useful for reflective colour displays, which have been fabricated by embedding colloidal particles in a polymer matrix whose swelling is controlled by an external electric field 6,7 . Dynamic control of diffraction has also be exploited to create colorimetric biosensors that change their structural colour upon specific binding of a biomolecule [8][9][10][11][12][13] . In all of these cases, the modulation of the photonic properties is controlled by changing the interparticle spacing, which requires fluid to flow out from the crystal; this transport is limited by diffusion, and thus rapid response requires small dimensions.…”