title: Rapid and label-free detection of protein a by aptamer-tethered porous silicon nanostructures.
abstract: Protein A, which is secreted by and displayed on the cell membrane of Staphylococcus aureus is an important biomarker for S. aureus. Thus, its rapid and specific detection may facilitate the pathogen identification and initiation of proper treatment. Herein, we present a simple, label-free and rapid optical biosensor enabling specific detection of protein A. Protein A-binding aptamer serves as the capture probe and is immobilized onto a nanostructured porous silicon thin film, which serves as the optical transducer element. We demonstrate high sensitivity of the biosensor with a linear detection range between 8 and 23μM. The apparent dissociation constant was determined as 13.98μM and the LoD is 3.17μM. Harnessing the affinity between protein A and antibodies, a sandwich assay format was developed to amplify the optical signal associated with protein A capture by the aptamer. Using this approach, we increase the sensitivity of the biosensor, resulting in a three times lower LoD.
authors.affiliation: Institute of Technical Chemistry, Leibniz Universität Hannover, Callinstr. 5, 30167 Hanover, Germany; Department of Biotechnology and Food Engineering, Technion Israel Institute of Technology, Technion City, 32000 Haifa, Israel.
authors.forename: Katharina
authors.initials: K
authors.lastname: Urmann
authors.affiliation: Institute of Technical Chemistry, Leibniz Universität Hannover, Callinstr. 5, 30167 Hanover, Germany; Institute for Bioprocessing and Analytical Measurement Techniques e.V., Rosenhof, 37308 Heilbad Heiligenstadt, Germany.
authors.forename: Peggy
authors.initials: P
authors.lastname: Reich
authors.affiliation: Institute of Technical Chemistry, Leibniz Universität Hannover, Callinstr. 5, 30167 Hanover, Germany.
authors.forename: Johanna-Gabriela
authors.initials: JG
authors.lastname: Walter
authors.affiliation: Institute for Bioprocessing and Analytical Measurement Techniques e.V., Rosenhof, 37308 Heilbad Heiligenstadt, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Beckmann
authors.affiliation: Department of Biotechnology and Food Engineering, Technion Israel Institute of Technology, Technion City, 32000 Haifa, Israel. Electronic address: esegal@technion.ac.il.
authors.forename: Ester
authors.initials: E
authors.lastname: Segal
authors.affiliation: Institute of Technical Chemistry, Leibniz Universität Hannover, Callinstr. 5, 30167 Hanover, Germany. Electronic address: scheper@iftc.uni-hannover.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Scheper
mesh_terms: D000906:Antibodies; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D007103:Immobilization / Q000379:methods; D007074:Immunoglobulin G; D049329:Nanostructures / Q000737:chemistry*; D055620:Optical Phenomena; D016062:Porosity; D012680:Sensitivity and Specificity; D012825:Silicon / Q000737:chemistry*; D013203:Staphylococcal Infections / Q000175:diagnosis; D013205:Staphylococcal Protein A / Q000302:isolation & purification*; D013211:Staphylococcus aureus / Q000378:metabolism
chemical_list: D000906:Antibodies; D052157:Aptamers, Nucleotide; D007074:Immunoglobulin G; D013205:Staphylococcal Protein A; D012825:Silicon
keywords: Aptamer; Label-free; Optical biosensor; Porous silicon; Protein A; Staphylococcus aureus