Luminescent diagnostics and quantitative assessment of malaria based on a lateral flow immunoassay with cdte quantum dots

Abstract

A lateral flow immunoassay (LFI) is a simple, low-cost and rapid diagnostic tool to identify various diseases by detecting analytes such as antibodies, parasites, or other relevant biomarkers. However, most LFIs can only confirm the presence or absence of a target analyte being applied as qualitative diagnostic tools. In addtion, the conventional LFIs, which require visual inspection of the test line, may demonstrate insufficient sensitivity for the mild form or early detection of infections and for this reason, the result can be falsely negative. This study presents the results of employing thioglycolic acid capped CdTe quantum dots as a probe to enhance luminescence and subsequently detection sensitivity in LFIs for diagnosis of malaria. The chemical route synthesis of thioglycolic acid capped CdTe quantum dots was optimized systematically by probing optical properties of the quantum dots. These optimized quantum dots of thioglycolic acid capped CdTe have been conjugated with the anti-malaria antibodies against HRP2 protein (P. falciparum) and were then incorporated into LFIs. Further, an image processing code has been developed to carry out the quantification of malaria parasites in terms of the ratio on intensities of control and test lines on the LFIs. The results have been compared with those obtained using the standard, colloidal gold based LFIs. It has been demonstrated that sensitivity and lower detection limits of malaria under low parasite concentration increase significantly due to enhanced luminescence of control and test lines under UV light, owing to the presence of thioglycolic acid capped CdTe quantum dots. It has also been shown that the image processing based quantification of malaria will likely minimize the chances of false negative results under low parasite concentration and assist in early diagnosis of malaria.