title: Protein-conjugated quantum dots interface: binding kinetics and label-free lipid detection.
abstract: We propose a label-free biosensor platform to investigate the binding kinetics using antigen-antibody interaction via electrochemical and surface plasmon resonance (SPR) techniques. The L-cysteine in situ capped cadmium sulfide (CdS; size < 7 nm) quantum dots (QDs) self-assembled on gold (Au) coated glass electrode have been covalently functionalized with apolipoprotein B-100 antibodies (AAB). This protein conjugated QDs-based electrode (AAB/CysCdS/Au) has been used to detect lipid (low density lipoprotein, LDL) biomolecules. The electrochemical impedimetric response of the AAB/CysCdS/Au biosensor shows higher sensitivity (32.8 kΩ μM(-1)/cm(2)) in the detection range, 5-120 mg/dL. Besides this, efforts have been made to investigate the kinetics of antigen-antibody interactions at the CysCdS surface. The label-free SPR response of AAB/CysCdS/Au biosensor exhibits highly specific interaction to protein (LDL) with association constant of 33.4 kM(-1) s(-1) indicating higher affinity toward LDL biomolecules and a dissociation constant of 0.896 ms(-1). The results of these studies prove the efficacy of the CysCdS-Au platform as a high throughput compact biosensing device for investigating biomolecular interactions.
authors.affiliation: Department of Science and Technology Centre on Biomolecular Electronics, Biomedical Instrumentation Section, CSIR-National Physical Laboratory , Dr. K. S. Krishnan Marg, New Delhi, Delhi 110012, India.
authors.forename: Md Azahar
authors.initials: MA
authors.lastname: Ali
authors.forename: S
authors.initials: S
authors.lastname: Srivastava
authors.forename: M K
authors.initials: MK
authors.lastname: Pandey
authors.forename: Ved V
authors.initials: VV
authors.lastname: Agrawal
authors.forename: R
authors.initials: R
authors.lastname: John
authors.forename: B D
authors.initials: BD
authors.lastname: Malhotra
mesh_terms: D053299:Apolipoprotein B-100 / Q000737:chemistry*; D019187:Cadmium Compounds / Q000737:chemistry; D003545:Cysteine / Q000737:chemistry; D058266:Dielectric Spectroscopy; D004566:Electrodes; D006046:Gold / Q000737:chemistry; D007700:Kinetics; D008055:Lipids / Q000032:analysis*; D045663:Quantum Dots; D013440:Sulfides / Q000737:chemistry; D020349:Surface Plasmon Resonance / Q000379:methods*
chemical_list: D053299:Apolipoprotein B-100; D019187:Cadmium Compounds; D008055:Lipids; D013440:Sulfides; C034939:cadmium sulfide; D006046:Gold; D003545:Cysteine