Cationic Surfactant-Based Colorimetric Detection of Plasmodium Lactate Dehydrogenase, a Biomarker for Malaria, Using the Specific DNA Aptamer

Abstract

A simple, sensitive, and selective colorimetric biosensor for the detection of the malarial biomarkers Plasmodium vivax lactate dehydrogenase (PvLDH) and Plasmodium falciparum LDH (PfLDH) was demonstrated using the pL1 aptamer as the recognition element and gold nanoparticles (AuNPs) as probes. The proposed method is based on the aggregation of AuNPs using hexadecyltrimethylammonium bromide (CTAB). The AuNPs exhibited a sensitive color change from red to blue, which could be seen directly with the naked eye and was monitored using UV-visible absorption spectroscopy and transmission electron microscopy (TEM). The reaction conditions were optimized to obtain the maximum color intensity. PvLDH and PfLDH were discernible with a detection limit of 1.25 pM and 2.94 pM, respectively. The applicability of the proposed biosensor was also examined in commercially available human serum.

Aromatic Surfactant as Aggregating Agent for Aptamer-Gold Nanoparticle-Based Detection of Plasmodium Lactate Dehydrogenase

“…Hence, the method reported by us is simpler and has potential economical implications. Conversely, the sensitivity reported in [17] using different aptamers was found to be better than the one obtained by us. However, the sensitivity reported by us is in the clinically relevant picomolar range [40] for the reliable detection of malaria.…”

“…The aptamer P38 so evolved through the SELEX process adapted by us did not bind to hLDH B. The selectivity information of the previously developed PvLDH aptasensor for the major interfering agent hLDH B was absent [17] for comparative analyses with the present work. The detection limits obtained by us (38 pg/ll with BCK and 55 pg/ll with NaCl) with P38 are marginally superior to the similar assay developed by Cheung et al [14].…”

“…CTAB has been shown to interact with single-and double-stranded DNA to form cubic and hexagonal nanostructures, respectively [38]. CTAB has also been used to develop an AuNP-based colorimetric assay for small molecules [39], ions [12] and proteins [17]. For the present work, we studied three different surfactants: (i) Alkyl dimethylbenzyl ammonium chloride, commonly known as Benzalkonium chloride (BCK) which contained an aromatic group and a long (C 12 ) alkyl chain; (ii) Hexadecyl (cetyl) trimethyl ammonium bromide (CTAB), which contained a single long (C 16 ) alkyl chain; and (iii) Didodecyl dimethyl ammonium bromide (DDAB) which contained two long (C 12 ) alkyl chains.…”

“…Several biomarkers for diagnosis of malaria have been investigated [13] among which Plasmodium-specific lactate dehydrogenase has emerged as a promising biomarker for malaria detection owing to its subtle structural and kinetic differences from the mammalian counterpart, leading to an increased interest in development of sensors that target this enzyme [14][15][16][17][18]. Here, we report a novel ssDNA aptamer developed against Plasmodium falciparum lactate dehydrogenase and its application potential to detect this biomarker through an aromatic cationic surfactant-based assay using gold nanoparticles as the optical sensing platform.…”

Gold nanoparticles and nanostructures in optical biosensors

“…49 Since some surfactants may promote aggregation, a novel technique has been demonstrated to detect malarial biomarkers plasmodium vivax lactate dehydrogenase and plasmodium falciparum lactate dehydrogenase (LDH). 50,51 Here, plasmodium LDH (pLDH) and the cationic surfactant hexadecyltrimethylammonium bromide (CTAB) competitively bind/assemble with pL1 aptamer, and free molecules of CTAB are found only if pLDH is present in the sample. These free molecules of CTAB cause AuNPs to aggregate.…”