Nano-aptamer Based Quantitative Detection of Chloramphenicol

Abstract

Chloramphenicol (CAP) is a broad-spectrum antibiotic, chronic use of which leads to aplastic anaemia and bone marrow suppression. Most countries, including India, have banned CAP from animal food production. However, it has still been detected in milk, honey and aquaculture products. The existing screening methods for CAP are time-consuming, laborious and expensive. Hence, there exists a need to develop an economical, fast and convenient method. In the current technique, single-stranded oligonucleotide molecule that binds specifically to CAP (aptamer) was used to protect synthesized gold nanocolloids from salt-induced aggregation, leading to colour change. The prepared nanocolloids were of size 7 nm and concentration 1.83 × 10⁻⁸ M. The buffer, salt, aptamer concentrations and incubation time were optimized. With optimized parameters, the proposed system could detect CAP up to 0.55 pg/mL in buffer, with a linear range of detection from 0.55 pg/mL to 55 μg/mL. The detection time was 30 min and cost was minimal (approximately Rs. 20 for 10 assays). Such a biosensing format, if extrapolated to real samples, can be used for rapid and effective quantitative screening for CAP in food matrices.