Abstract:Gold nanoparticles (AuNP) are widely used for reaction catalysis. The common understanding is that the smaller the particles, the more reactive they are. It is reported here that this is not always the case for citrate (Ct) or polyvinylpyrrolidone (PVP) stabilized AuNP in the catalytic reduction of 4‐nitrophenol with sodium borohydride (NaBH4), when the total surface area is kept constant. The results prove that for AuNP in the size range of 10–58 nm, the reactivity increases with increasing particle diameter … Show more
“…4 c, d. Zeta potential is considered as an indicator of the stability of nanoparticles. This negative value of zeta potential is due to the presence of three deprotonated anionic carboxyl groups of citrate ions which verify the repulsive interaction between nanoparticles and aim to prevent the agglomeration of AuNPs [ 26 , 27 ]. Fig.…”
Multi-drug resistance (MDR) in addition to the damage to non-malignant normal cells are the most difficult in cancer treatment. Drug delivery and Plasmonic photothermal therapy based on the use of resonant metallic nanoparticles have developed as promising techniques to destroy cancer cells selectively. In the present work, gold nanoparticles (AuNPs) were synthesized using trisodium citrate. The prepared AuNPs have a small size of 14 ± 4 nm and exhibit high stability with Zeta potential − 18 mV, AuNPs showed higher photothermal heating efficiency compared to irradiation with a 532 nm laser alone on the breast cancer cell line (MCF-7). Treatment of MCF-7 cells with 0.125 mM AuNPs coupled with laser irradiation for 6 min was found to significantly reduce (34%) the cell viability compared to 5% obtained with AuNPs in the same concentration and 26% with laser irradiation for 6 min without AuNPs. Moreover, the prepared AuNPs were used as an anticancer drug carrier for Doxorubicin (Dox), upon loading Dox to AuNPs there was a slight increase in the particle size to 16 ± 2 nm, FT-IR spectroscopic results showing the binding of Dox to AuNPs was through the –NH group. The potential cytotoxicity of the DOX@AuNPs nanocomposite was significantly increased compared to free DOX on the MCF7 cell line with a decrease in IC50. All these results suggested the potential use of AuNPs as therapeutic photothermal agents and drug carriers in cancer therapy.
“…4 c, d. Zeta potential is considered as an indicator of the stability of nanoparticles. This negative value of zeta potential is due to the presence of three deprotonated anionic carboxyl groups of citrate ions which verify the repulsive interaction between nanoparticles and aim to prevent the agglomeration of AuNPs [ 26 , 27 ]. Fig.…”
Multi-drug resistance (MDR) in addition to the damage to non-malignant normal cells are the most difficult in cancer treatment. Drug delivery and Plasmonic photothermal therapy based on the use of resonant metallic nanoparticles have developed as promising techniques to destroy cancer cells selectively. In the present work, gold nanoparticles (AuNPs) were synthesized using trisodium citrate. The prepared AuNPs have a small size of 14 ± 4 nm and exhibit high stability with Zeta potential − 18 mV, AuNPs showed higher photothermal heating efficiency compared to irradiation with a 532 nm laser alone on the breast cancer cell line (MCF-7). Treatment of MCF-7 cells with 0.125 mM AuNPs coupled with laser irradiation for 6 min was found to significantly reduce (34%) the cell viability compared to 5% obtained with AuNPs in the same concentration and 26% with laser irradiation for 6 min without AuNPs. Moreover, the prepared AuNPs were used as an anticancer drug carrier for Doxorubicin (Dox), upon loading Dox to AuNPs there was a slight increase in the particle size to 16 ± 2 nm, FT-IR spectroscopic results showing the binding of Dox to AuNPs was through the –NH group. The potential cytotoxicity of the DOX@AuNPs nanocomposite was significantly increased compared to free DOX on the MCF7 cell line with a decrease in IC50. All these results suggested the potential use of AuNPs as therapeutic photothermal agents and drug carriers in cancer therapy.
“…140 The reduction of 4-nitrophenol increased with an increase in the diameter of Au nanoparticles in the range of 10–58 nm. 141 Hierarchical supports have potential for embedding size-selected metal particles, either confined in their pores or on their exterior surface, which can be tailored for specific reactions.…”
The article presents knowledge-driven design of multifunctional hierarchically structured gold on ceria catalyst for environmental applications. Variety of configurations of gold-decorated ceria has been obtained by precise control of the...
“…To improve the stability and catalytic performance of composite particles, chemical bonding methods are often applied in the composite process to fulfill the dual bonding forces' action induced by physical and chemical interaction. 23 Gold nanoparticles (AuNPs) have been widely used in the fields of detection, 24 catalysts, 25 and sensors 26 due to their high dielectric characteristics, 27 catalytic activity, 28 and ability to attach to a variety of macromolecules. Poly(N-isopropylacrylamides) (PNIPAM) with excellent temperature-sensitive properties 29 is often used in biomedicine, 30 tissue engineering, 31 sensors, 32 etc.…”
Stimuli-responsive hybrid nanoparticles used for controllable
catalysis
have been attracting increasing attention. This study aims to prepare
hybrid microgels with excellent temperature-sensitive colorimetric
and catalytic properties through combining the surface plasmon resonance
properties of gold nanoparticles (AuNPs) with the temperature-sensitive
properties of poly(N-isopropylacrylamide) (PNIPAM)-based
microgels. Microgels with hydroxy groups (MG-OH) were prepared by
soap-free emulsion polymerization, using N-isopropylacrylamide
as the main monomer, hydroxyethyl methylacrylate as the functional
monomer, N,N′-methylene bisacrylamide
as the crosslinker, and 2,2′-azobis(2-methylpropionamidine)
dihydrochloride as an initiator to ensure the microgels are positively
charged. Furthermore, chemical modification on the surface of MG-OH
was carried out by 3-mercaptopropyltriethoxysilane to obtain thiolated
microgels (MG-SH). Two kinds of hybrid nanoparticles, AuNPs@MG-OH
and AuNPs@MG-SH, were self-assembled, through electrostatic interaction
between positive MG-OH and negative citrate-stabilized AuNPs as well
as through synergistic bonding of electrostatic interaction and Au–S
bonding between positive MG-SH and negative AuNPs. The morphology,
stability, temperature-sensitive colorimetric properties, and catalytic
properties of hybrid microgels were systematically investigated. Results
showed that although both AuNPs@MG-OH and AuNPs@MG-SH exhibit good
temperature-sensitive colorimetric properties and controllable catalytic
properties for the reduction reaction of p-nitrophenol, AuNPs@MG-SH
with synergistic bonding has better stability and higher catalytic
performance than AuNPs@MG-OH. This work has good competitiveness against
known PNIPAM-based materials and may provide an effective method for
preparing smart catalysts by self-assembly with stimuli-responsive
polymers, which has a great potential application for catalyzing a
variety of reactions.
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