A simple aptamer/gold nanoparticle aggregation-based colorimetric assay for oxidized low-density lipoprotein determination

Abstract

Oxidized low-density lipoprotein (oxLDL) is the leading cause of atherosclerosis and cardiovascular diseases. Here, we created a simple colorimetric assay for sensitive and specific determination of oxLDL using a selective aptamer coupled with salt-induced gold nanoparticle (AuNP) aggregation. The aptamer was chosen by Systematic Evolution of Ligands by Exponential Enrichment to obtain a novel selective sequence towards oxLDL (as 5′-CCATCACGGGGCAGGCGGACAAGGGGTAAGGGCCACATCA-3′). Mixing a 5 μM aptamer solution with an aliquot of a sample containing oxLDL followed by adding AuNP solution (OD = 1) and 80 mmol L-1 NaCl achieved rapid results within 19 min: linear response to oxLDL from 0.002 to 0.5 μmol L-1 with high selectivity, a recovery accuracy of 100–111% at the 95% confidence interval, and within-run and between-run precision of 1–6% and 1–5% coefficient variations, respectively. Artificial serum diluted at least 1:8 with distilled water, analyzed by the aptamer-based colorimetric assay, showed excellent correlation with conventional thiobarbituric acid reactive substances (TBARS) (R2 = 0.9792) as a rapid colorimetric method without the need for sample preparation other than dilution.