title: Ultrasensitive electrochemical immunoassay for surface array protein, a Bacillus anthracis biomarker using Au-Pd nanocrystals loaded on boron-nitride nanosheets as catalytic labels.
abstract: Bacillus anthracis, the causative agent of anthrax, is a well known bioterrorism agent. The determination of surface array protein (Sap), a unique biomarker for B. anthracis can offer an opportunity for specific detection of B. anthracis in culture broth. In this study, we designed a new catalytic bionanolabel and fabricated a novel electrochemical immunosensor for ultrasensitive detection of B. anthracis Sap antigen. Bimetallic gold-palladium nanoparticles were in-situ grown on poly (diallyldimethylammonium chloride) functionalized boron nitride nanosheets (Au-Pd NPs@BNNSs) and conjugated with the mouse anti-B. anthracis Sap antibodies (Ab2); named Au-Pd NPs@BNNSs/Ab2. The resulting Au-Pd NPs@BNNSs/Ab2 bionanolabel demonstrated high catalytic activity towards reduction of 4-nitrophenol. The sensitivity of the electrochemical immunosensor along with redox cycling of 4-aminophenol to 4-quinoneimine was improved to a great extent. Under optimal conditions, the proposed immunosensor exhibited a wide working range from 5 pg/mL to 100 ng/mL with a minimum detection limit of 1 pg/mL B. anthracis Sap antigen. The practical applicability of the immunosensor was demonstrated by specific detection of Sap secreted by the B. anthracis in culture broth just after 1h of growth. These labels open a new direction for the ultrasensitive detection of different biological warfare agents and their markers in different matrices.
authors.affiliation: Biosensor Development Division, Defence Research and Development Establishment, Jhansi Road, Gwalior, Madhya Pradesh 474002, India. Electronic address: mksharma@drde.drdo.in.
authors.forename: Mukesh Kumar
authors.initials: MK
authors.lastname: Sharma
authors.affiliation: Biosensor Development Division, Defence Research and Development Establishment, Jhansi Road, Gwalior, Madhya Pradesh 474002, India.
authors.forename: J
authors.initials: J
authors.lastname: Narayanan
authors.affiliation: Vertox Laboratory, Defence Research and Development Establishment, Jhansi Road, Gwalior, Madhya Pradesh 474002, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Pardasani
authors.affiliation: Analytical Discipline & Centralized Instrument Facility, CSIR-Central Salt & Marine Chemicals Research Institute, Bhavnagar 364021, India.
authors.forename: Divesh N
authors.initials: DN
authors.lastname: Srivastava
authors.affiliation: Biosensor Development Division, Defence Research and Development Establishment, Jhansi Road, Gwalior, Madhya Pradesh 474002, India.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Upadhyay
authors.affiliation: Biotechnology Division, Defence Research and Development Establishment, Jhansi Road, Gwalior, Madhya Pradesh 474002, India. Electronic address: akgoel73@yahoo.co.uk.
authors.forename: Ajay Kumar
authors.initials: AK
authors.lastname: Goel
mesh_terms: D000818:Animals; D000881:Anthrax / Q000175:diagnosis* / Q000382:microbiology; D055910:Antibodies, Immobilized / Q000737:chemistry; D001408:Bacillus anthracis / Q000737:chemistry / Q000302:isolation & purification*; D015415:Biomarkers / Q000737:chemistry; D015374:Biosensing Techniques; D001895:Boron / Q000737:chemistry; D055664:Electrochemical Techniques; D006046:Gold / Q000737:chemistry; D007118:Immunoassay / Q000379:methods; D008562:Membrane Glycoproteins / Q000302:isolation & purification*; D053768:Metal Nanoparticles / Q000737:chemistry; D051379:Mice; D010165:Palladium / Q000737:chemistry
chemical_list: D055910:Antibodies, Immobilized; D015415:Biomarkers; D008562:Membrane Glycoproteins; C055764:S-layer proteins; D010165:Palladium; D006046:Gold; D001895:Boron
keywords: B. anthracis; Boron nitride; Catalytic bionanolabel; Electrochemical Immunosensor; Redox cycle; Surface array protein