A Photonic Crystal Protein Hydrogel Sensor for Candida albicans

Abstract

We report two-dimensional (2D) photonic crystal (PC) sensing materials that selectively detect Candida albicans (C. albicans). These sensors utilize Concanavalin A (Con A) protein hydrogels with a 2D PC embedded on the Con A protein hydrogel surface, that multivalently and selectively bind to mannan on the C. albicans cell surface to form crosslinks. The resulting crosslinks shrink the Con A protein hydrogel, reduce the 2D PC particle spacing, and blue-shift the light diffracted from the PC. The diffraction shifts can be visually monitored, measured with a spectrometer, or determined from the Debye diffraction ring diameter. Our unoptimized hydrogel sensor has a detection limit of around 32 CFU/mL for C. albicans. This sensor distinguishes between C. albicans and those microbes devoid of cell-surface mannan such as the gram-negative bacterium E. coli. This sensor provides a proof-of-concept for utilizing recognition between lectins and microbial cell surface carbohydrates to detect microorganisms in aqueous environments.

Chromogenic Photonic Crystal Sensors Enabled by Multistimuli‐Responsive Shape Memory Polymers

“…Each intermediate state exhibits a specific and easily perceived diffractive color, which can be used as a colorimetric indicator of the analyte concentration. In sharp contrast to most state‐of‐the‐art photonic crystal sensors, the multiple temporary configurations of the SMP‐based chromogenic sensors are structurally fixed and can be stored under ambient conditions for a long period of time. These “frozen” intermediate states enable reliable optical and microstructural characterization of the SMP membranes at any time interval during the reversible SM cycle, which greatly facilitate fundamental mechanistic studies on intriguing nanoscopic SM effects and swelling dynamics of macroporous SMP membranes with complex hierarchical porous networks.…”

“…The visually perceived color changes associated with stimuli‐responsive PBG shifts in active photonic crystals have also been extensively exploited as a more convenient transduction mechanism than traditional electrical pathways for developing novel, low‐cost chemical sensors . Various photonic crystal geometries ranging from mesoporous 1D Bragg stacks and 2D photonic crystal fibers to 3D inverted photonic crystals and porous silicon membranes, coupled with many stimuli‐responsive materials, such as hydrogels (including those with specific analyte‐binding ligands), oxides, semiconductors, metals, and polymers, have enabled sensitive colorimetric and/or spectroscopic detection of a large variety of chemical and biological analytes (e.g., glucose, proteins, metal ions, alcohols, and water) . Drastic color shifts of photonic crystal sensors are commonly achieved through changes in lattice constants (for example, induced by swelling/deswelling of hydrogels) and/or effective refractive indices (e.g., caused by liquid uptake in porous photonic crystals) .…”

Bottom-Up Assembly and Applications of Photonic Materials

“…They made use of the shrinking of the hydrogel when exposed to the pathogen to modify the particle spacing in the 2D array, which translated to visually evident blue shifts of diffracted light that could be readily detected. The sensor is a proof of concept for utilizing recognition between microbial cell surface carbohydrates and lectins to detect microorganisms in aqueous environments [159]. Men et al reported that optical sensors based on hydrogel films with 2D colloidal arrays on both surfaces exhibited enhanced diffraction intensity and avoided the curling problems on traditional hydrogel films with only a single colloidal array on one side [160].…”

Synthesis of Polypyrrole Inverse Opals through an Air–Water Interface Polymerization Method and Their Application in Dye‐Sensitized Solar Cells

“…Inverse opals (IOs), featuring a 3D ordered interconnected pore system with extremely uniform pore size, have received great attention owing to their wide applications in photonic crystals, sensors, dye‐sensitized solar cells (DSSCs), catalysis, etc. Normally, a colloidal crystal obtained by self‐assembly of microspheres is employed as template for the infiltration of metal oxides, carbon, polymer, conducting polymers, etc., and after the removal of the microspheres IOs of corresponding materials could be obtained.…”