Detection of organophosphorus pesticide - Malathion in environmental samples using peptide and aptamer based nanoprobes

The contamination of environment with pesticides residues has necessitated the development of rapid, easy and highly sensitive approaches for the detection of pesticides. Thus, the prime objective of the present strategy was sensing of malathion, a toxic organophosphorus pesticide, widely used in agricultural fields, employing aptamer, cationic peptide and unmodified gold nanoparticles. The role of peptide was carefully evaluated to exploit its potential in colorimetric detection of pesticides. The peptide, when linked to the aptamer renders the gold nanoparticles free and therefore, red in color. However, when the aptamer is associated with malathion, the peptide remains available to cause the aggregation of the nanoparticles and turn the suspension blue. The methodology utilizes the optical changes of the gold nanoparticles for the colorimetric detection of malathion. The method was found to be linear in the range of 0.01-0.75 nM with a limit of detection as 1.94 pM which is significantly lower than the other available reports. Moreover, the sensitivity of the developed nanoparticle based peptide aptasensor was tested in real samples and the results implied the high practicability of the method. Therefore, the present approach may pave a way for the sensitive, yet simple detection of different analytes without the need of expensive instrumentation. (C) 2016 Elsevier B.V. All rights reserved.