Synthesis and Functionalization of Gold Nanoparticles by Using of Poly Functional Amino Acids

Synthesis and characterization of two functionalized gold nanoparticles by using of two poly functional amino acids (L-Arginine and L-Aspartic acid) are reported. The gold nanoparticles were reduced by sodium citrate and functionalized with L-Arginine at the pH of 7 and 11 and L-Aspartic acid at the pH of 7. Transmission electron microscopy, UV-Vis spectroscopy, dynamic light scattering, zeta potential and agarose gel electrophoresis techniques were used for characterization and identification. The transmission electron microscopy image showed well distributed particles with an average size of about 10 nm. At the pH of 7, the results obtained, verified that the interaction between L-Arginine and gold nanoparticles was electrostatic and it was covalent/ coordinate in the case of L-Aspartic acid. The functionalized gold nanoparticles possessing free amine and carboxylic groups (poly functional amino acid) could play an important role in conjugating biomolecules such as proteins (e.g. antibodies) and DNA in nanomedicinal and nanobiotechnological applications. In addition, if the pH of the target in vivo environment is constant, functionalized gold nanoparticles bound electrostatically will be preferred. On the other hand, if the pH of the target in vivo environment is variable, then amino acid capped gold nanoparticles bound covalently/coordinately are recommended.