Facile colorimetric sensor development for sequential detection of coralyne and calf-thymus DNA via tannic acid-assisted silver nanoparticles

Abstract

Owning to unique size dependent optical properties, plasmonic nanoparticles have been explored as chemical read-outs for assaying various biological and chemical analytes. We propose colorimetric sensing strategy based on tannic acid mediated silver nanoparticles (TA-AgNPs) for the detection of Coralyne (COR) and calf thymus DNA (CT-DNA). Aggregation of TA-AgNPs is observed on addition of COR molecule because of electrostatic interaction between them, which is established by change in color from yellow to brown. TA-AgNPs/COR based colorimetric probe was then employed for CT-DNA detection, utilizing anti-aggregation of nanoparticles. Formation of intercalated complex between CT-DNA and COR prevents the aggregation of nanoparticles and color of TA-AgNPs solution remains yellow. Under optimum sensing conditions, extent of aggregation and anti-aggregation of TA-AgNPs was studied. A linear correlation between absorbance value at 437 nm and COR concentration is obtained in the range of 0 to 1.2 μM with detection limit of 0.44 μM. TA-AgNPs/COR based detection probe exhibited linear response to CT-DNA in concentration range of 0 to 7.62 μM with a limit of detection down to 1.63 μM. The applicability of sensing strategy verified by analysis of COR and CT-DNA in human urine samples, which demonstrated the practical utility of method in biomedical applications.