Designing a two-stage colorimetric sensing strategy based on citrate reduced gold nanoparticles: Sequential detection of Sanguinarine (anticancer drug) and visual sensing of DNA

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2021-02, Vol.246, p.119039, Article 119039
• Main Authors: Khurana, Sonia, Kukreti, Shrikant, Kaushik, Mahima
• Format: Article
• Language: English
• Subjects: Aggregation; Anticancer drug; Calf thymus DNA; Colorimetric sensing; Gold nanoparticles; Sanguinarine
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2020.119039

Distance dependent optical properties of colloidal gold nanoparticles offer designing of colorimetric sensing modalities for detection of a variety of analytes. Herein, we report a simple and facile colorimetric detection assay for an anti-cancer drug, Sanguinarine (SNG) and Calf Thymus DNA (Ct-DNA) based on citrate reduced gold nanoparticles (CI-Au NPs). The electrostatic interaction between SNG and CI-Au NPs induce aggregation of Au NPs accompanied with visible colour change of colloidal solution. The assay conditions like salt concentration, pH and reaction time had been adjusted to achieve highly sensitive and fast colorimetric response. Furthermore, the optimized CI-Au NPs/SNG sensing system is used for the detection of Ct-DNA based on the mechanism of anti-aggregation of CI-Au NPs. The simultaneous presence of SNG and Ct-DNA prevent aggregation of Au NPs owing to preferential formation of Ct-DNA-SNG intercalation complex and colour of the Au NPs solution tends to remain red, depending on the concentration of Ct-DNA in solution. The degree of aggregation and anti-aggregation of CI-Au NPs was monitored using Transmission electron microscopic (TEM) measurements and UV–Visible spectrophotometry by analysing the ratio of absorptions for aggregated and dispersed Au NPs. The intercalation mode of binding between SNG and Ct-DNA in CI-Au NPs/SNG sensing system was determined by Fluorescence spectral studies and UV-thermal melting studies. The absorption ratio (A627/A525) of Au NPs exhibited a linear correlation with SNG concentrations in the range from 0 to 0.9 μM with detection limit as 0.046 μM. This optical method can determine Ct-DNA as low as 0.36 μM and the calibration is linear for concentration range 0 to 5 μM. The proposed sensing strategy enables detection as well as quantification of SNG & Ct-DNA in real samples with satisfactory results and finds application in drug or DNA monitoring. We report a new, facile colorimetric sensing assay for detection of Sanguinarine and Calf thymus DNA (Ct-DNA) based on the Citrate reduced Au NPs using Sanguinarine ions as an aggregation agent and DNA intercalating agent. The electrostatic interaction between positively charged Sanguinarine ions and CI-Au NPs solution leads to the aggregation of nanoparticle solution, which appear in the form of colour change from red to blue. The presence of Ct-DNA in solution effectively mask Sanguinarine induced aggregation of CI-Au NPs due to prior formation of Ct-DNA- Sanguinar