Article

Low density lipoprotein detection based on antibody immobilized self-assembled monolayer: investigations of kinetic and thermodynamic properties.

Department of Science and Technology Centre on Biomolecular Electronics, National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi-110012, India.
The Journal of Physical Chemistry B (impact factor: 3.7). 10/2009; 113(43):14405-12. DOI:10.1021/jp903661r pp.14405-12
Source: PubMed

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.

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Keywords

AAB-LDL interaction
 
AAB-modified ATP/Au surface
 
AAB/ATP/Au immunosensor
 
active sites
 
adsorption process
 
fabrication
 
Freundlich adsorption models
 
Gibb's free energy
 
Human plasma low density lipoprotein
 
immobilizing antiapolipoprotein B
 
interaction process
 
Langmuir adsorption isotherm
 
LDL immunosensors
 
probability studies
 
quartz crystal microbalance
 
reaction kinetics
 
self-assembled monolayer
 
surface plasmon resonance
 
thermodynamic parameters
 
water molecules