Spontaneous Preparation of Highly Stable Gold Nanoparticle Stabilized with ω-Sulfonylated Alkylsulfanylaniline

Preparation, characterization, and stability evaluation of gold nanoparticles stabilized by ω-sulfonylated alkylsulfanylaniline have been described. The particle solution was obtained by the spontaneous reaction of HAuCl₄ and ω-sulfonylated alkylsulfanylaniline in boiling water. It showed a deep red color, owing to surface plasmon resonance of the resulting gold nanoparticles. The size and shape of the nanoparticles were pH-dependent, and pH 8 was found to be the most suitable condition to prepare stable nanoparticles with an average size of 11.2 ± 5.9 nm. The resulting particle solution was stable for a wide range of pH (3-13) and in phosphate-buffered saline (PBS) solution. The nanoparticles were storable as dried powder for at least two weeks, and were redispersible in water or PBS to give almost the same absorption spectra as the freshly prepared solution. Nanoparticle modification was achieved by simply adding thiol molecules to the particle solution.