Aggregation, dissolution and cyclic regeneration of Ag nanoclusters based on pH-induced conformational changes of polyethyleneimine template in aqueous solutions

Dong, Jiancheng; Qü, Fei; Li, Nian Bing; Luo, Hong Qun

doi:10.1039/c4ra14812f

Cited by 17 publications

(9 citation statements)

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“…3 The loss of the lattice was accompanied by the appearance of the size-dependent physicochemical properties of Figure 3a and b describes the changes in the fluorescence and UV-vis absorption spectra during the etching process, showing that the fluorescence intensity at 428 nm and absorbance at 349 nm increased synchronously, and an obvious blue shift was observed at the UV-vis absorption peak within 12 h after the addition of GSH, which showed that the nanoparticles in the solution changed from larger nanocrystals to small nanoclusters, and the increasing absorbance showed the increase in the concentration of Ag NCs as the etching process progressed. 35,36 The color of the Ag colloid solution changed from the original dark brown (before adding GSH) to reddish-brown (72 h after the addition of GSH) and then to colorless after 168 h (Figure 3c), and the blue emission of the diluted Ag NCs solutions brightened correspondingly over time (Figure 3d).…”

Section: Resultsmentioning

confidence: 99%

The pH-switchable agglomeration and dispersion behavior of fluorescent Ag nanoclusters and its applications in urea and glucose biosensing

et al. 2016

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Water-soluble fluorescent Ag nanoclusters (Ag NCs) with distinct pH-switchable agglomeration and spectral signal responses are prepared using a facile etching method. Increased and decreased pH cause the Ag NCs to switch between agglomeration and dispersion, accompanied by decreases in and recoveries of fluorescence intensity and absorbance. The pH switchable behavior of the Ag NCs is attributed to carboxyl groups on the nanocluster surface that are rich in the citrate and amido functional groups of ligands (glutathione), creating an easily formed, weak molecular interaction among Ag NCs (for example, hydrogen bonding) and maintaining a balance in the colloidal solution, whereas a change in pH will disrupt the balance, leading to the reversible agglomeration of Ag NCs and the switchable spectral signal response. In addition, because urea and glucose can change the pH of a solution by producing NH 3 and gluconic acid in enzyme-catalyzed reactions, the pH-switchable behavior of the Ag NCs is used to develop them as an optical probe to establish a regenerated biosensing platform for the sensitive and selective detection of urea and glucose, and the test results are satisfactory. INTRODUCTIONMetal nanoparticles on an~2 nm scale are defined as metal nanoclusters, and they show physicochemical properties that are significantly different from those of their bulk form. Fluorescent metal nanoclusters composed of a small number of atoms have attracted research interest because of their unique properties and molecule-like behavior. 1,2 In recent decades, many fluorescent metal nanoclusters, especially nanoclusters of Au and Ag, among noble metals, have been reported, and the ligands that stabilize these small nanoparticles have a key role in their fundamental properties: (i) ligands can influence optical properties by transferring their charge to the metal cores or by directly donating delocalized electrons contained on them to the metal cores; 3,4 (ii) surface ligands can determine the physical properties of nanoclusters (for example, hydrophily and hydrophoby), and amphiphilic metal nanoclusters can be produced by skillfully controlling the type and amount of ligands; 5 (iii) the functional groups of the surface ligands determine the chemical properties of the metal nanoclusters; thus, fluorescent nanoclusters can be more widely used as probes for detecting various targets. 6,7 Moreover, published studies show that the optical properties of Au and Ag nanoclusters (Ag NCs) protected by thiols are more

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Section: Resultsmentioning

confidence: 99%

The pH-switchable agglomeration and dispersion behavior of fluorescent Ag nanoclusters and its applications in urea and glucose biosensing

et al. 2016

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“…Formaldehyde (100 µL, 30%) was then added dropwise to the mixture and incubated for 10 min at 70 °C, and then at room temperature for 24 h to obtain bPEI‐capped AgNCs. AgNCs were purified by dialysis against water in 1 kDa MWCO membranes for 24 h. UV–vis absorption spectra exhibited peaks at 268 and 354 nm indicating the formation of AgNCs …”

Section: Methodsmentioning

confidence: 99%

Nanosilver Mitigates Biofilm Formation via FapC Amyloidosis Inhibition

Huma

Javed

Zhang

et al. 2020

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Multidrug resistance of bacteria is a major challenge due to the wide‐spread use of antibiotics. While a range of strategies have been developed in recent years, suppression of bacterial activity and virulence via their network of extracellular amyloid has rarely been explored, especially with nanomaterials. Here, silver nanoparticles and nanoclusters (AgNPs and AgNCs) capped with cationic branched polyethylenimine polymer are synthesized, and their antimicrobial potentials are determined at concentrations safe to mammalian cells. Compared with the ultrasmall AgNCs, AgNPs entail stronger binding to suppress the fibrillization of FapC, a major protein constituent of the extracellular amyloid matrix of Pseudomonas aeruginosa. Both types of nanoparticles exhibit concentration‐dependent antibiofilm and antimicrobial properties against P. aeruginosa. At concentrations of 1 × 10−6 m or below, both the bactericidal activity of AgNCs and the antibiofilm capacity of AgNPs are associated with their structure‐mediated bio–nano interactions but not ion release. For AgNPs, specifically, their antibiofilm potency correlates with their capacity of FapC fibrillization inhibition, but not with their bactericidal activity. This study demonstrates the antimicrobial potential of safe nanotechnology through the novel route of amyloidosis inhibition.

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“…It is well known that the size distribution and agglomeration extent of metal nanoparticles could be effectively controlled by regulating the protected templates. 18 The strategy to achieve this goal is to control the growth of nanoparticles in monodisperse templates, such as porous membranes, dendrimers or reversed micelles. [19][20][21] As a special monodisperse macromolecule with successive layers or generations of branch units surrounding a central core, dendrimer is considered as a superb template to synthesize metal nanoparticles with narrow size distribution owing to their unique molecule properties.…”

Section: Introductionmentioning

confidence: 99%

Controllable synthesis of silver nanoparticles in hyperbranched macromolecule templates for printed flexible electronics

Zhang

2015

RSC Adv.

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Aggregation, dissolution and cyclic regeneration of Ag nanoclusters based on pH-induced conformational changes of polyethyleneimine template in aqueous solutions

Abstract: The cyclic-conversion among polyethyleneimine-templated Ag nanoclusters, Ag nanoparticles, and Ag(i) ions was realized by adjusting pH and adding corresponding reductant.

Cited by 17 publications

References 50 publications

The pH-switchable agglomeration and dispersion behavior of fluorescent Ag nanoclusters and its applications in urea and glucose biosensing

The pH-switchable agglomeration and dispersion behavior of fluorescent Ag nanoclusters and its applications in urea and glucose biosensing

Nanosilver Mitigates Biofilm Formation via FapC Amyloidosis Inhibition

Controllable synthesis of silver nanoparticles in hyperbranched macromolecule templates for printed flexible electronics

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