Pt nanoparticle tethered DNA assemblies for enhanced catalysis and SERS applications

Abstract

The influence of noble metals in the fields of catalysis and surface enhanced Raman scattering (SERS) is an emerging and interesting area of applied materials research. The application of bio-scaffolds such as DNA for staging nanoparticles (NPs) could also give an immense enhancement in SERS. The chemical reduction (bottom-up approach) is proposed here for the synthesis of Pt NPs staged on DNA assemblies. Using NaBH₄ to reduce Pt⁴⁺ ions to metallic Pt and keeping the concentration of DNA fixed, Pt NP–DNA assemblies were synthesized by changing Pt concentration in the molar ratios of 0.003, 0.004, 0.005 and 0.006 M. The as-synthesised NPs show the average chain length of ∼103 nm and average particle size below 5 nm. The Pt NP–DNA assemblies gave better activity in both catalysis and SERS. In catalysis, various nitro compounds were tested using NaBH₄ as a reducing agent, where we observed the high rate constant (k) of 6.45 × 10⁻¹ min⁻¹ for 2-nitroaniline using the Pt NPs–DNA (0.006 M). In SERS, the enhancement factor (EF) was calculated to be 2.52 × 10⁵ for Pt NP–DNA assemblies (0.003 M). Stability of the Pt NP–DNA assemblies was monitored, and they were found to be highly stable for more than six months when kept in the refrigerator. With the high activity in catalysis and SERS, the Pt NP–DNA assemblies also have the potential for application in other fields of research in the near future.