Spectroscopic Study on the Reaction of L-Cysteine in Rh(PVP) Nanoparticle Colloidal Solution

Abstract

We have investigated the reaction of L-cysteine in Rh(PVP) nanoparticle colloidal solution using S-K and Cl-K edges near edge X-ray absorption fine structure and circular dichroism measurements. In our previous study, it was shown using S-K edge NEXAFS technique that cystine molecules were synthesized by dissolving L-cysteine into the Rh(PVP) nanocolloidal solution. In this study, we have revealed the details of cystine synthesis reaction. There are four reactions, which are the adsorption of L-cysteine on Rh nanoparticle surface, the L-cysteine decomposition to cysteine thiolate, the formation of the complex structure similar to (NH4)3[RhCl6] and the synthesis of cystine molecule on Rh nanoparticle surface. These reactions start immediately after dissolving L-cysteine into the nanocolloidal solution.

Adsorption Reaction of Amino Acid Molecule on Pd Thin Layer Surface Constructed by Nano-dots under Water Environment

“…To identify a chemisorbed adsorbate on each substrate surfaces, the assignation of NEXAFS peak positions is necessary. From the results of previous studies, we have judged the peak positions of L-cysteine thiolate and atomic S [2,8,12,13]. The spectra for L-cysteine aqueous solution and the NiAl(111) substrate without dipping into L-cysteine aqueous solution under dry environment are also shown as standard and background.…”

“…For example Gohda et al have fabricated Rh(PVP) * Corresponding author: tsukada.chie@e.mbox.nagoya-u.ac.jp nanoparticles that are synthesized by reducing Rh ion in ethanol-water solvent with water-solution polymers of PVP (polyvinylpyrrolidone), and added L-cysteine powder to the nano-colloidal solution [2,3]. They have revealed an adsorption reaction between Rh nanoparticles and the L-cysteine under water environment.…”

Spectroscopic Study on the Adsorption Reaction of L-Cysteine on Cu nanoparticle/Ag under <i>in vivo</i> condition

“…Therefore, we think that the adsorption reaction of L-Cysteine on Cu nanoparticle surface is influenced by the electron donation from Cu nanoparticle to substrate. Figure 3 shows the S K-edge NEXAFS spectra for samples from 1 to 4, L-Cysteine powder [7] and atomic S on Rh(100) [8]. To compare the chemical state of adsorbed L-Cysteine, all spectra for samples are normalized by the edge jump.…”