Gold Nanoparticles as Colorimetric Sensors for the Detection of DNA Bases and Related Compounds

Results regarding interaction of colloidal gold solutions with nucleobases, including uracil (U), as well as its sulfur derivatives, 2-thiouracil (2TU) and 4-thiouracil (4TU), cytosine (C), adenine (A), and guanine (G), as well as urea and thiourea (TU), are reported. Anionic stabilized citrate gold nanoparticles (AuNPs) were synthesized by reducing the tetrachloroaurate (III) trihydrate with trisodium citrate. The surface plasmon resonance (SPR) band was used in the characterization of synthesized AuNPs, as well as transmission electron microscope (TEM) imaging, which was used in the characterization of dispersed and aggregated gold nanoparticles. Interactions of nucleobases with the gold surface was analyzed by following the plasmon absorbance band red shift of the AuNPs. The sulfur-containing compounds adsorbed to the nanoparticle surfaces by chemisorption-type interactions; with TU and 4TU, the process is accompanied by a sudden change in color; in contrast, 2TU forms stable functionalized gold nanoparticles. Urea and U do not adsorb to nanoparticle surfaces, but the other heterocyclic bases containing nitrogen interact effectively with the gold surface, causing the assembly of nanoparticles, even though the interparticle self-aggregation process was slower than that mediated by either TU or 4TU. The method is efficient in the colorimetric detection of nucleobases and derivatives at concentration levels on the order of 1 µM.

Metal nanoparticle catalyzed charge rearrangement in selenourea probed by surface-enhanced Raman scattering

The adsorption behavior of selenourea (SeU) on Ag and Au nanoparticles was investigated using the surface-enhanced Raman scattering technique in combination with X-ray photoelectron spectroscopy and density functional theoretical calculations.

Investigation of the in situ generation of oxide-free copper nanoparticles using pulsed-laser ablation of bulk copper in aqueous solutions of DNA bases

The pulsed-laser ablation method was used as a facile and green approach to prepare oxide-free copper nanoparticles, and was performed by laser ablation of a copper target in aqueous solutions of the DNA bases.

Positively charged, surfactant-free gold nanoparticles for nucleic acid delivery

Synthesis of positively charged, surfactant-free, not cytotoxic 2–200 nm gold nanoparticles in water by seeding growth method; a powerful candidate for nucleic acid delivery application.