Kinetics and mechanism of reduction of silver(I) by ascorbic acid

Neogeometric copper nanoparticles (CuNPs) have various applications yet its synthesis still proves to be challenging with regards to self-assembly and uniformity control. This study aimed to synthesize shape-specific CuNPs in the biomedical application of ascertaining skin permeation and retention of the CuNPs as a drug delivery system. The approach to the shape design involved the dual control of two surfactants to direct the shape organisation of the nanoparticles (NPs) while an interesting aspect of the study showed the competitive adsorption of the surfactants onto the nanocrystal facets to direct facet growth. The resulting copper nanoparticles were characterised using X-ray diffraction (XRD) and electron diffraction spectra analysis (EDS) for elemental and crystalline analysis. Thermogravimetric Analysis (TGA) identified the degradation of the surfactant coat and the synthesis of a novel copper-polymer complex and extensive transmission electron microscopy (TEM) was conducted to determine the nanoparticle morphology. Epidermal skin tissue served as the model for permeation studies of five idealistic nano-geometries and investigated its application in drug delivery with regards to cellular internalisation and transbarrier transport of the geometric CuNPs. A mechanistic consideration for shape control is discussed.

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“…In addition to its use as a reducing agent, ascorbic acid also functions as a capping agent [18,19]. …”

Section: Resultsmentioning

confidence: 99%

Neo-Geometric Copper Nanocrystals by Competitive, Dual Surfactant-Mediated Facet Adsorption Controlling Skin Permeation

et al. 2016

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“…It behaves as a vinylogous carboxylic acid with involvement of the lone electron pair on the hydroxyl group, the double bond of the ring structure, and the carbonyl double bond acting as a conjugated system. 13 Mushran et al have monitored the progress of the reaction between ascorbic acid and silver ions and have demonstrated the stoichiometric equation for the reduction of silver ions with ascorbic acid (AH 2 ) as shown in Scheme 2. The pH of the L-ascorbic acid solution used in the present study was 2.63.…”

Section: Resultsmentioning

confidence: 99%

Time resolved growth of membrane stabilized silver NPs and their catalytic activity

et al. 2014

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Formation of highly stable metal nanostructures in a Nafion® membrane with various aspect ratios has been of considerable research interest in recent years. However, there is a need for a proper understanding of the growth mechanism of such nanostructures in Nafion® (sometimes larger than the size of water-sulfonate ionic clusters of the membrane). In this work, the early growth kinetics of silver nanoparticles (NPs) in Nafion®-117 ion-exchange membrane during in situ L-ascorbic acid reduction of Ag + ions by time resolved in situ small-angle X-ray scattering (SAXS) using synchrotron radiation with a time resolution of 50 ms are revealed for the first time. The SAXS analyses, corroborated by transmission electron microscopy, showed that the sizes of NPs increase rapidly together with their number density until they attain a certain size that could be accommodated in the $5 nm water-sulfonate ionic clusters. Further growth takes place either by self-agglomeration of the particles ejected out from the water-sulfonic acid clusters or by continuous reduction of metal ions on the existing NP surfaces (uniformly or on a specific plane) leading to formation of bigger nanostructures with various aspect ratios. The time resolved information of NP growth provides an opportunity for the controlled synthesis of metal NPs with a definite size, shape and size distribution for a specific application. The catalytic properties of Ag NPs formed in the membrane were examined using borohydride reduction of a model dye methylene blue. It was observed that smaller Ag NPs with a mean diameter $3 nm, confined in the hydrophilic clusters of the Nafion® matrix, have reasonably good catalytic activity and a lower lag time for the onset of reduction.

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“…Zur Untersuchung des Einflusses einer Heterogenkatalyse wurden der Reaktionslosung Silbercluster zugesetzt, die in einfacher Weise durch Reduktion eines Teils der Silberionen mit Ascorbinsaure hergestellt wurden. Diese Redoxreaktion verlauft auch in schwach saurer Losung in den hier angewendeten Konzentrationen innerhalb weniger Minuten weitgehend quantitativ, wenn auch nicht als einfache homogene Reaktion zweiter Ordnung, wie vor einiger Zeit berichtet [29], sondern vollig analog zur Reaktion zwischen p-Phenylendiamin und Silber(I), wie durch Verfolgung der zeitlichen Ascorbinsaureabnahme im Zweiwellenlangenphotometer gesehen werden kann. Daher durften die so gebildeten Silbercluster groBe Ahnlichkeit mit den bei der p-Phenylendiaminreduktion entstehenden Clustern besitzen.…”

Section: Experimentellesunclassified

Mechanismus der quasi-homogenen Oxidation von p-Phenylendiaminen mit Silbernitrat

Nickel¹,

Rühl²,

Zhou³

1986

Zeitschrift Für Physikalische Chemie

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Oxidation / Cluster / p-Phenylenediamines / Silver / Photographic development The redox reaction between p-phenylenediamines and silver nitrate in aqueous acid solution was observed optically in a double wavelength photometer. In presence of a noble metal plate or larger clusters of silver, production of p-semiquinonediimines respective silver starts immediately, whereas without clusters present at the beginning of the reaction the maximum reaction rate is attained only after a certain induction period. The length of this induction period depends on the pH and the concentration of pphenylenediamine, but not on the silver ion concentration. It is not the number of the clusters that influences the induction period, but their size. The rate of the main reaction, however, is proportional to the number of the clusters formed. In dilute solutions the main reaction is of first order concerning both of the two reactants, in concentrated solution, however, it is of smaller order. Die Redoxreaktion zwischen p-Phenylendiaminen und Silbernitrat in saurer waBriger Losung wurde optisch in einem Zweiwellenlangenphotometer untersucht. In Gegenwart von Edelmetallblech oder groBeren Silberclustern setzt die p-Semichinondiimin -bzw.Silberbildung sofort ein, dagegen wird ohne besonderen Clusterzusatz die maximale Reaktionsgeschwindigkeit erst nach einer Induktionsperiode erreicht, deren Lange vom pH und von der p-Phenylendiamin-Konzentration, nicht aber von der Silberionenkonzentration abhangt. Die Zahl der entstehenden Cluster nimmt dabei kaum EinfluB auf die Dauer der Induktionsperiode, wohl aber ihre GroBe. Die Geschwindigkeit der Hauptreaktion ist demgegeniiber der Zahl der gebildeten Cluster proportional und in verdiinnter Losung 1. Ordnung hinsichtlich jedes der beiden Reaktanten, in konzentrierter Losung jedoch von kleinerer Ordnung.

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Kinetics and mechanism of reduction of silver(I) by ascorbic acid

Cited by 33 publications

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Neo-Geometric Copper Nanocrystals by Competitive, Dual Surfactant-Mediated Facet Adsorption Controlling Skin Permeation

Neo-Geometric Copper Nanocrystals by Competitive, Dual Surfactant-Mediated Facet Adsorption Controlling Skin Permeation

Time resolved growth of membrane stabilized silver NPs and their catalytic activity

Mechanismus der quasi-homogenen Oxidation von p-Phenylendiaminen mit Silbernitrat

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