title: 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.
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260 (USA).
authors.forename: Zhongyu
authors.initials: Z
authors.lastname: Cai
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260 (USA).
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Kwak
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260 (USA).
authors.forename: David
authors.initials: D
authors.lastname: Punihaole
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260 (USA).
authors.forename: Zhenmin
authors.initials: Z
authors.lastname: Hong
authors.affiliation: Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (USA).
authors.forename: Sachin S
authors.initials: SS
authors.lastname: Velankar
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260 (USA). xinyuliu@pitt.edu.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260 (USA). asher@pitt.edu.
authors.forename: Sanford A
authors.initials: SA
authors.lastname: Asher
mesh_terms: D015374:Biosensing Techniques; D002176:Candida albicans / Q000166:cytology / Q000302:isolation & purification*; D003208:Concanavalin A / Q000737:chemistry*; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D017785:Photons
chemical_list: D003208:Concanavalin A; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate
keywords: gels; microbes; photonic crystals; proteins; sensors