Differentiation of oxidized low density lipoproteins by nanosensors

Oxidized low density lipoprotein (oxLDL) is considered a biomarker for acute heart attack in patients with coronary artery disease (CAD). LDL cholesterol in the circulatory system can undergo oxidative modification to oxidized LDL (oxLDL), leading to the development of CAD. We tested whether indium oxide (In2O3) nanowires network- and carbon nanotube network-based field effect transistors (FETs) were able to differentiate the LDL cholesterol between the reduced (native LDL) and the oxidized state (oxLDL). LDL samples isolated from human plasma were exposed to In2O3 FETs, and conductivities and gating characteristics were obtained as current versus drain-source voltage (ID–VDS), and current versus gate-source voltage (ID–VGS). A higher conductivity was observed in the LDL sample containing 15.1% oxLDL relative to the sample containing 4.4% oxLDL. The results were validated by high performance liquid chromatography (HPLC). Next, carbon nanotube network-based FETs conjugated with anti-copper oxLDL antibody were exposed to the LDL samples. Distinct conductivities between nLDL and oxLDL were also observed from the ID versus time domain curve in the presence of bovine serum albumin (BSA), demonstrating nano-scale sensors as potential lab-on-a-chip devices for detection of oxLDL cholesterol.