Design of hybrid aptamer-molecularly imprinted polymer nanoparticles for selective binding of oxidized low-density lipoprotein in an ELISA-mimic system.

Oxidized low-density lipoprotein (oxLDL) is the leading cause of atherosclerosis and cardiovascular disease development. An enzyme-linked immunosorbent assay (ELISA)-mimic system for sensitive and specific oxLDL determination was developed using selective aptamer-molecularly imprinted polymer nanoparticles (AP-MIP NP) coupled with an immunology-based colorimetric assay. The AP-MIP NP were synthesized using solid-phase molecular imprinting by incorporating aptamers into the MIP NP cavities. This resulted in AP-MIP NP with diameters of 108 ± 28 nm. For AP-MIP NP-ELISA-mimic assay development, the surface of a microplate was coated with the novel AP-MIP NP capture receptors at a concentration of 0.1 mg mL to capture oxLDL. The reaction time between AP-MIP NP and oxLDL was 20 min. Horseradish peroxidase conjugated anti-oxLDL polyclonal antibody at a concentration of 0.6 μg mL was used as the detection antibody, with a linear response ranging from 24.72 to 1,600 μg dL. The recovery accuracy was 89-106 %. Within-run precision was 3.3-6.7 % of the coefficient of variation, while between-day precision was 3.8-7.1 %. The AP-MIP NP-coated wells were stored at room temperature for one month without a loss of binding ability, retaining over 91 % binding ability after three regeneration cycles. Human serum diluted 1:10 and analyzed by the AP-MIP NP-ELISA-mimic assay showed high correlation with conventional ELISA (R = 0.9779). This assay achieved rapid results within 95 min, compared to ELISA at 195 min. The high binding ability and selectivity of the AP-MIP NP shows promise as a selective material against oxLDL for the ELISA-mimic system and other applications.