Self-assembled gold nanoparticles on the serpentine networks of Calf Thymus-DNA Langmuir-Blodgett films as efficient SERS sensing platform: Fabrication and its application in thiram detection

Abstract

Fabrication of efficient SERS active substrates from the Langmuir-Blodgett (LB) films of Calf Thymus-DNA (CT-DNA) molecule after incubation into gold nanocolloid for 24 h has been presented. Relaxation kinetics of CT-DNA molecules at the air-water interface has been explicitly studied. The experimental observations from UV–Vis electronic absorption spectra together with the FESEM and AFM images of CT-DNA molecule organized in LB film collectively suggest the presence of H-type aggregated domains due to plane-to-plane self-association of the CT-DNA molecules on the surface of the LB film. XPS spectrum of the as prepared substrate has been unveiled to identify its chemical compositions while their morphological features are explored from the FESEM and AFM images. The SERS efficacy of the substrate has been tested with the 4-Mercaptopyridine (4-MPy) molecule at trace concentration. SERS enhancement factors ranging from 106–107 orders of magnitude have been evaluated for the characteristic bands of the 4-MPy molecule. The substrate not only exhibits appreciable spectral reproducibility, but it also confirms its stability and uniformity. The as prepared SERS active substrate has also been used for thiram detection at ultrasensitive concentration.