Size-controlled preparation of fluorescent gold nanoparticles using pamoic acid

Abstract

We previously showed that pamoic acid (PA) could be utilized as a reducing and capping reagent for preparing monodispersed gold nanoparticles (AuNPs) with diameters of 10.8 nm. Here, we show that the size of these PA-capped AuNPs can be varied in a controlled manner by changing the pH used in the preparation process. By changing the added amount of NaOH in the PA solution before mixing with HAuCl 4 , several types of AuNPs were prepared at different pH values. The absorption spectra showed a red shift of the characteristic peak of the AuNPs with decreasing pH, indicating the formation of larger AuNPs. The TEM results confirmed this relationship between AuNP size and pH, and the zeta potentials indicated that the AuNPs capped with PA were more stable than the AuNPs prepared by citrate reduction method. Furthermore, the PA-capped AuNPs showed much higher fluorescence intensities than those of citrate-capped AuNPs, which is due to the fluorescence of PA. The sizes of PA-capped spherical AuNPs could also be controlled by a seed-mediated growth approach. However, the original PAcapped AuNPs, with diameters of 10.8 nm, exhibited the highest fluorescence intensities among the various types of PA-capped AuNPs that were grown. In addition to conferring fluorescence properties to the AuNPs, the capping by PA also provided the nanoparticles with carboxylate groups.

Biogenic Synthesis of Gold Nanoparticles on a Green Support as a Reusable Catalyst for the Hydrogenation of Nitroarene and Quinoline

“…The appearance of peaks at binding energies of 84.33 and 87.97 eV are associated with the 4f 7/2 and 4f 5/2 gold orbitals with a splitting orbital coupling constant Δ of 3.75 eV, respectively (Fig 3b). [51,52] The formation of metallic gold (Au o ) at a binding energy of 84.33 eV in AuNPs/ JPS catalyst is also detected, further proving that JPS acts as a reductant to form metallic Au. The peaks at binding energies of 284.48 and 286.12 eV indicate À CÀ CÀ bond and À CÀ OÀ C group, respectively.…”

Influence of Pamoic Acid as a Complexing Agent in the Thermal Preparation of NiO Nanoparticles: Application to Electrochemical Water Oxidation

“…Organic moieties that act as a surfactant, stabilizer, reductant, or ligand play an important role in determining the sizes and shapes of NPs. In early experiments, we prepared monodisperse 10.8 nm florescent gold NPs using pamoic acid (PA) (Scheme ) as a reductant and stabilizer ,. Disodium salt pamoic acid (Na 2 PA) provided monodisperse tin‐doped indium oxide (ITO) NPs by acting as an organic additive and dehydrating agent .…”

Sol-gel synthesis and third-order optical nonlinearity of Au nanoparticles doped monolithic glass

“…Au has attracted wide concern over the years, the research on Au can be traced back to the colloidal Au reported in the scientific literature by Faraday in 1857 [17]. As the most stable metal nanoparticles, gold nanoparticles (Au NPs) not only present fascinating aspects such as their assembly of multiple types involving material science, the behavior of the individual particles, size-related electronic, magnetic and unique optical properties but also their applications in nanotechnology, biology, and catalysis, as well as the excellent nonlinear properties and potential prospect in the nonlinear optical devices [12,[18][19][20]. Particularly, Au NP glasses [18,21,22] act as the most widely studied nonlinear material because of the unique plasmon resonance absorption, chemical inertness, and thermal stability.…”

“…As the most stable metal nanoparticles, gold nanoparticles (Au NPs) not only present fascinating aspects such as their assembly of multiple types involving material science, the behavior of the individual particles, size-related electronic, magnetic and unique optical properties but also their applications in nanotechnology, biology, and catalysis, as well as the excellent nonlinear properties and potential prospect in the nonlinear optical devices [12,[18][19][20]. Particularly, Au NP glasses [18,21,22] act as the most widely studied nonlinear material because of the unique plasmon resonance absorption, chemical inertness, and thermal stability. A. I. Ryasnyanskiy et al [22] synthesized gold nanoparticles embedded in Al 2 O 3 , ZnO, and SiO 2 matrices by radiofrequency magnetron sputtering technique and investigated their third-order nonlinear optical properties by Z-scan method using a frequency-doubled Q-switched Nd…”