Low-Density Lipoprotein Sensor Based on Molecularly Imprinted Polymer.

Increased level of low-density lipoprotein (LDL) strongly correlates with incidence of coronary heart disease. We synthesized novel molecularly imprinted polymers (MIP) as biomimetic specific receptors to establish rapid analysis of LDL levels. For that purpose the ratios of monomers acrylic acid (AA), methacrylic acid (MAA), and N-vinylpyrrolidone (VP), respectively, were screened on 10 MHz dual-electrode quartz crystal microbalances (QCM). Mixing MAA and VP in the ratio 3:2 (m/m) revealed linear sensor characteristic to LDL cholesterol (LDL-C) from 4 to 400 mg/dL or 0.10-10.34 mmol/L in 100 mM phosphate-buffered saline (PBS) without significant interference: high-density lipoprotein (HDL) yields 4-6% of the LDL signal, very-low-density-lipoprotein (VLDL) yields 1-3%, and human serum albumin (HSA) yields 0-2%. The LDL-MIP sensor reveals analytical accuracy of 95-96% at the 95% confidence interval with precision at 6-15%, respectively. Human serum diluted 1:2 with PBS buffer was analyzed by LDL-MIP sensors to demonstrate applicability to real-life samples. The sensor responses are excellently correlated to the results of the standard technique, namely, a homogeneous enzymatic assay (R(2) = 0.97). This demonstrates that the system can be successfully applied to human serum samples for determining LDL concentrations.