Aptamer based Lateral Flow Assays for Rapid and Sensitive Detection of CKD marker Cystatin C

Abstract

A novel aptamer-antibody pair-based lateral flow assay was designed to rapidly quantify Cystatin C (CysC). CysC is a small protein that can be expressed by all nucleated cells. It is rarely influenced by factors other than Glomerular filtration rate (GFR), an indicator of renal function chronic kidney diseases (CKD). That makes it a reliable biomarker for the measurement of the GFR. Aptamers bind specifically to the target molecules, it is less expensive, more stable, and lack immunogenicity. The aptamers became a valuable tool in clinical diagnosis and made them a great alternative to antibodies. In this study, we designed and developed an aptamer- antibody pair-based quantitative lateral flow assay for the CysC quantification in the human sample. A highly sensitive and specific CysC sensor was achieved by conjugating CysC selective aptamers to the organic dye Alexafluor-647. When CysC molecules are present in the sample, they form a complex with the designed aptamers to bind, especially with the CysC antibody immobilized on the lateral flow assay strip's test zone. Important parameters that influence the sensitivity in lateral flow assay, such as the concentration of aptamers in the conjugation pad, were evaluated to give the optimum assay performance. The assay was precise and has a limit of detection of 0.013 µg/µl was shown better than the antibody-based kit. In summary, the resulting LFA aptamers-based sensor provides a rapid, sensitive, cost-effective point of care sensor for CysC detection in human samples.