title: Low density lipoprotein detection based on antibody immobilized self-assembled monolayer: investigations of kinetic and thermodynamic properties.
abstract: Human plasma low density lipoprotein (LDL) immunosensor based on surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) was fabricated by immobilizing antiapolipoprotein B (AAB) onto self-assembled monolayer (SAM) of 4-aminothiophenol (ATP). The AAB/ATP/Au immunosensor can detect LDL up to 0.252 microM (84 mg/dL) and 0.360 microM (120 mg/dL) with QCM and SPR, respectively. The SPR and QCM measurements were further utilized to study the reaction kinetics of the AAB-LDL interaction. The adsorption process involved was explored using Langmuir adsorption isotherm and Freundlich adsorption models. The thermodynamic parameters such as change in Gibb's free energy (DeltaG(ads)), change in enthalpy (DeltaH(ads)), and change in entropy (DeltaS(ads)) determined at 283, 298, and 308 K revealed that the AAB-LDL interaction is endothermic in nature and is governed by entropy. Kinetic, thermodynamic, and sticking probability studies disclosed that desorption of the water molecules from the active sites of AAB and LDL plays a key role in the interaction process and increase in temperature favors binding of LDL with the AAB/ATP/Au immunosensor. Thus, the studies were utilized to unravel the most important subprocess involved in the adsorption of LDL onto AAB-modified ATP/Au surface that may help in the fabrication of LDL immunosensors with better efficiency.
authors.affiliation: Department of Science and Technology Centre on Biomolecular Electronics, National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi-110012, India.
authors.forename: Zimple
authors.initials: Z
authors.lastname: Matharu
authors.forename: Amay Jairaj
authors.initials: AJ
authors.lastname: Bandodkar
authors.forename: G
authors.initials: G
authors.lastname: Sumana
authors.forename: Pratima R
authors.initials: PR
authors.lastname: Solanki
authors.forename: E M I Mala
authors.initials: EM
authors.lastname: Ekanayake
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kaneto
authors.forename: Vinay
authors.initials: V
authors.lastname: Gupta
authors.forename: B D
authors.initials: BD
authors.lastname: Malhotra
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry; D055910:Antibodies, Immobilized / Q000276:immunology / Q000378:metabolism*; D015374:Biosensing Techniques / Q000379:methods*; D006046:Gold / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D008077:Lipoproteins, LDL / Q000097:blood*; D011791:Quartz / Q000737:chemistry; D013438:Sulfhydryl Compounds; D020349:Surface Plasmon Resonance / Q000379:methods*; D013816:Thermodynamics
chemical_list: D000814:Aniline Compounds; D055910:Antibodies, Immobilized; D008077:Lipoproteins, LDL; D013438:Sulfhydryl Compounds; D011791:Quartz; D006046:Gold; C064316:4-aminothiophenol