title: Highly stable porous silicon-carbon composites as label-free optical biosensors.
abstract: A stable, label-free optical biosensor based on a porous silicon-carbon (pSi-C) composite is demonstrated. The material is prepared by electrochemical anodization of crystalline Si in an HF-containing electrolyte to generate a porous Si template, followed by infiltration of poly(furfuryl) alcohol (PFA) and subsequent carbonization to generate the pSi-C composite as an optically smooth thin film. The pSi-C sensor is significantly more stable toward aqueous buffer solutions (pH 7.4 or 12) compared to thermally oxidized (in air, 800 °C), hydrosilylated (with undecylenic acid), or hydrocarbonized (with acetylene, 700 °C) porous Si samples prepared and tested under similar conditions. Aqueous stability of the pSi-C sensor is comparable to related optical biosensors based on porous TiO(2) or porous Al(2)O(3). Label-free optical interferometric biosensing with the pSi-C composite is demonstrated by detection of rabbit IgG on a protein-A-modified chip and confirmed with control experiments using chicken IgG (which shows no affinity for protein A). The pSi-C sensor binds significantly more of the protein A capture probe than porous TiO(2) or porous Al(2)O(3), and the sensitivity of the protein-A-modified pSi-C sensor to rabbit IgG is found to be ~2× greater than label-free optical biosensors constructed from these other two materials.
authors.affiliation: Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, People's Republic of China.
authors.forename: Chun Kwan
authors.initials: CK
authors.lastname: Tsang
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Kelly
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Sailor
authors.forename: Yang Yang
authors.initials: YY
authors.lastname: Li
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002244:Carbon / Q000737:chemistry*; D004355:Drug Stability; D004563:Electrochemistry; D005663:Furans / Q000737:chemistry; D007118:Immunoassay; D007074:Immunoglobulin G / Q000032:analysis / Q000276:immunology; D055620:Optical Phenomena; D016062:Porosity; D011817:Rabbits; D012825:Silicon / Q000737:chemistry*
chemical_list: D005663:Furans; D007074:Immunoglobulin G; D002244:Carbon; C012986:furfuryl alcohol; D012825:Silicon