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Increased levels of plasma oxLDL, which is the oxidized fraction of Low Density Lipoprotein (LDL), are
associated with atherosclerosis, an inflammatory disease, and the subsequent development of severe
cardiovascular diseases that are today a major cause of death in modern countries. It is therefore
important to find a reliable and fast assay to determine oxLDL in serum. A new immunosensor
employing three monoclonal antibodies (mAbs) against oxLDL is proposed in this work as a quick and
effective way to monitor oxLDL. The oxLDL was first employed to produce anti-oxLDL monoclonal
antibodies by hybridoma cells that were previously obtained. The immunosensor was set-up by selfassembling
cysteamine (Cyst) on a gold (Au) layer (4 mm diameter) of a disposable screen-printed
electrode. Three mAbs were allowed to react with N-hydroxysuccinimide (NHS) and
ethyl(dimethylaminopropyl)carbodiimide (EDAC), and subsequently incubated in the Au/Cys. Albumin
from bovine serum (BSA) was immobilized further to ensure that other molecules apart from oxLDL
could not bind to the electrode surface. All steps were followed by various characterization techniques
such as electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). The
analytical operation of the immunosensor was obtained by incubating the sensing layer of the device in
oxLDL for 15 minutes, prior to EIS and SWV. This was done by using standard oxLDL solutions prepared
in foetal calf serum, in order to simulate patient's plasma with circulating oxLDL. A sensitive response
was observed from 0.5 to 18.0 mg mL 1
. The device was successfully applied to determine the oxLDL
fraction in real serum, without prior dilution or necessary chemical treatment. The use of multiple
monoclonal antibodies on a biosensing platform seemed to be a successful approach to produce a
specific response towards a complex multi-analyte target, correlating well with the level of oxLDL within
atherosclerosis disease, in a simple, fast and cheap way.
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Royal Society of Chemistry