New insights on the formation of gold nanoparticles and Pluronic nanocomposites: Kinetics and thermodynamics parameters

Gomes, Deizilene S. B.; Paterno, Leonardo G.; Santos, Aline B. S.; Garay, Aisel Valle; Mertz, Damien; Freitas, Sonia María de; Soler, Maria A. G.

doi:10.1016/j.molliq.2018.07.042

Cited by 7 publications

(11 citation statements)

References 30 publications

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“…The best fit of the binding isotherm occurred with four sequential binding sites. This model is useful for systems with non-identical sites, such as the binding of multiple ligands to transition metal ions and association in nanocomposites 49 . The binding processes are spontaneous, as indicated by Gibbs free energy values from −5.5 to −10.0 kcal/mol.…”

Section: Discussionmentioning

confidence: 99%

Structural and biochemical analysis reveals how ferulic acid improves catalytic efficiency of Humicola grisea xylanase

Oliveira

Garay

Souza

et al. 2022

Sci Rep

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Humicolagrisea var. thermoidea is an aerobic and thermophilic fungus that secretes the GH11 xylanase HXYN2 in the presence of sugarcane bagasse. In this study, HXYN2 was expressed in Pichiapastoris and characterized biochemically and structurally in the presence of beechwood xylan substrate and ferulic acid (FA). HXYN2 is a thermally stable protein, as indicated by circular dichroism, with greater activity in the range of 40–50 °C and pH 5.0–9.0, with optimal temperature and pH of 50 °C and 6.0, respectively. FA resulted in a 75% increase in enzyme activity and a 2.5-fold increase in catalytic velocity, catalytic efficiency, and catalytic rate constant (kcat), with no alteration in enzyme affinity for the substrate. Fluorescence quenching indicated that FA forms a complex with HXYN2 interacting with solvent-exposed tryptophan residues. The binding constants ranged from moderate (pH 7.0 and 9.0) to strong (pH 4.0) affinity. Isothermal titration calorimetry, structural models and molecular docking suggested that hydrogen bonds and hydrophobic interactions occur in the aglycone region inducing conformational changes in the active site driven by initial and final enthalpy- and entropy processes, respectively. These results indicate a potential for biotechnological application for HXYN2, such as in the bioconversion of plant residues rich in ferulic acid.

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Section: Discussionmentioning

confidence: 99%

Structural and biochemical analysis reveals how ferulic acid improves catalytic efficiency of Humicola grisea xylanase

Oliveira

Garay

Souza

et al. 2022

Sci Rep

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“…Gomes et al used cyclic voltammetry to test the redox potential of gold nanoparticles synthesized in the presence of the block copolymer Pluronic F127. F127 has an oxidation potential of +0.11 V, which is lower than the Au(III) reduction potential of +0.56 V, and therefore, F127 is able to reduce chloroaurate [34]. Since P123 has a similar molecular structure as F127, it is supposed to also have the capacity to reduce chloroaurate.…”

Section: The Effect Of the Type Of Alkali Metal Ionmentioning

confidence: 99%

Solution-Phase Synthesis of KCl Nanocrystals Templated by PEO-PPO-PEO Triblock Copolymers Micelles

Sun,

Li,

et al. 2024

Polymers

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The current work introduces the synthesis of inorganic salt nano/micro-crystals during the reduction of hydrogen tetrachloroaurate(III) by Pluronic triblock copolymers (P123, PEO20–PPO70–PEO20). The morphologies and component were confirmed using an electron microscope with an electronic differential system (EDS), and the crystal structures were determined with X-ray diffraction (XRD). The morphologies highly depend on the concentrations of Pluronic and pH values. The mean size of the nanocrystal and hollow micro-crystal were controlled typically in the range of 32–150 nm (side length) and 1.4 μm, respectively. Different from the electrospray–ionization (EI) method, a model in which KCl forms a supersaturated solution in the micellar core of Pluronic is used to explain the formation process. This work provides the new insight that inorganic salt nanocrystals could be synthesized with the template of micelles in pure aqueous solutions.

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“…Isothermal calorimetry titration performed in a subsequent study revealed that during the formation of F127:Au nanocomposites, at a very low F127:Au molar ratio (below 0.05), the association between tetrachloroaurate anion (AuCl 4 − ) and F127 is the prevailing event (exothermic process). However, at a larger F127:Au (0.05 to 0.12), particle growth becomes dominant when the Au 0 nuclei and poly(propylene oxide) block interact by entropic hydrophobic forces [31]. In parallel, cyclic voltammetry indicated that complete reduction of Au 3+ occurs only above the critical micellar concentration (cmc) (~0.2-0.8 wt%) of F127 [31].…”

Section: Introductionmentioning

confidence: 99%

“…However, at a larger F127:Au (0.05 to 0.12), particle growth becomes dominant when the Au 0 nuclei and poly(propylene oxide) block interact by entropic hydrophobic forces [31]. In parallel, cyclic voltammetry indicated that complete reduction of Au 3+ occurs only above the critical micellar concentration (cmc) (~0.2-0.8 wt%) of F127 [31]. Another study suggested that the size and polydispersity of these AuNPs depend almost exclusively on the copolymer concentration [32].…”

Section: Introductionmentioning

confidence: 99%

UV-Accelerated Synthesis of Gold Nanoparticle–Pluronic Nanocomposites for X-ray Computed Tomography Contrast Enhancement

et al. 2023

Self Cite

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Eco-friendly chemical methods using FDA-approved Pluronic F127 (PLU) block copolymer have garnered much attention for simultaneously forming and stabilizing Au nanoparticles (AuNPs). Given the remarkable properties of AuNPs for usage in various fields, especially in biomedicine, we performed a systematic study to synthesize AuNP-PLU nanocomposites under optimized conditions using UV irradiation for accelerating the reaction. The use of UV irradiation at 254 nm resulted in several advantages over the control method conducted under ambient light (control). The AuNP-PLU-UV nanocomposite was produced six times faster, lasting 10 min, and exhibited lower size dispersion than the control. A set of experimental techniques was applied to determine the structure and morphology of the produced nanocomposites as affected by the UV irradiation. The MTT assay was conducted to estimate IC50 values of AuNP-PLU-UV in NIH 3T3 mouse embryonic fibroblasts, and the results suggest that the sample is more compatible with cells than control samples. Afterward, in vivo maternal and fetal toxicity assays were performed in rats to evaluate the effect of AuNP-PLU-UV formulation during pregnancy. Under the tested conditions, the treatment was found to be safe for the mother and fetus. As a proof of concept or application, the synthesized Au:PLU were tested as contrast agents with an X-ray computed tomography scan (X-ray CT).

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New insights on the formation of gold nanoparticles and Pluronic nanocomposites: Kinetics and thermodynamics parameters

Cited by 7 publications

References 30 publications

Structural and biochemical analysis reveals how ferulic acid improves catalytic efficiency of Humicola grisea xylanase

Structural and biochemical analysis reveals how ferulic acid improves catalytic efficiency of Humicola grisea xylanase

Solution-Phase Synthesis of KCl Nanocrystals Templated by PEO-PPO-PEO Triblock Copolymers Micelles

UV-Accelerated Synthesis of Gold Nanoparticle–Pluronic Nanocomposites for X-ray Computed Tomography Contrast Enhancement

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