Sensing array based on molecularly imprinted polymers for simultaneous assessment of lipoproteins

Abstract

A three-electrode quartz crystal microbalance (QCM) sensor array served for simultaneously and selectively detecting the concentrations of two atherosclerosis biomarkers, namely low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Molecularly imprinted polymers (MIPs) for both lipoproteins, namely LDL-MIP and HDL-MIP, containing monomer mixtures of methacrylic acid and N-vinylpyrrolidone at the ratio 3:2 and 2:3, respectively, served as the selective recognition elements for LDL and HDL. The third electrode carried the corresponding non-imprinted polymer (NIP) and acted as reference electrode. The sensor array revealed detection range toward LDL/HDL mixture standards (defined through their cholesterol LDL-C, and HDL-C) in 10 mM phosphate-buffered saline (pH 7.4) in relevant ranges of 3–400 mg/dL LDL-C and 8–200 mg/dL HDL-C. Coefficients of variation indicating sufficient precision of sensor array are at 2%–17%. Intra-assay test reveal correlation coefficients of R2 = 0.9839 and 0.9809 for LDL-C and HDL-C determination, respectively. Hence, the array is inherently useful as a quantitative detector for both lipoproteins during one measurement. In contrast to current clinical detection methods, analysis in this case requires only one step without sample pretreatment. It achieves results simultaneously within 7 min. Array sensing shows the ability to distinguish the responses of (lipo)protein classes using principal component analysis (PCA), demonstrating applicability for both qualitative and quantitative assays. This opens up the way for MIP multisensory arrays, for instance to assess other lipoproteins.