Ultrasmall fluorescent silver nanoclusters: Protein adsorption and its effects on cellular responses

Li, Shang; Dörlich, René M.; Trouillet, Vanessa; Bruns, Michael; Nienhaus, G. Ulrich

doi:10.1007/s12274-012-0238-x

Cited by 128 publications

(98 citation statements)

References 58 publications

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“…[10][11][12][13][14][15][16][17][18][19][20][21][22][23] Compared to QDs, [24] Au and Ag nanoclusters (NCs) are more biocompatible and can be readily bioconjugated; other advantages include their extrememly small size, good photostability, and low toxicity; thus, fluorescent noble-metal NCs have been recognized as a promising candidate for cell labeling, biosensing, and photo-therapy applications. [25][26][27][28][29][30] However, a general issue lies in the lower quantum yield (QY) of metal NCs compared to QDs and organic dyes, which significantly limits the applications of metal NCs. Various approaches have been developed to synthesize noble metal NCs with enhanced fluorescence, for example: 1) engineering the particle surface by using different ligands, such as DHLA, [31] dendrimers, [32] polymers, [33] DNA, [34,35] peptides, and proteins; [36][37][38][39][40][41][42][43][44] 2) controlling the metal core size [45] or doping the core with other metal atoms.…”

mentioning

confidence: 99%

A 200‐fold Quantum Yield Boost in the Photoluminescence of Silver‐Doped Ag_xAu_25−x Nanoclusters: The 13 th Silver Atom Matters

et al. 2014

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The rod-shaped Au 25 nanocluster possesses a low photoluminescence quantum yield (QY = 0.1 %) and hence is not of practical use in bioimaging and related applications. Herein, we show that substituting silver atoms for gold in the 25-atom matrix can drastically enhance the photoluminescence. The obtained Ag x Au 25Àx (x = 1-13) nanoclusters exhibit high quantum yield (QY = 40.1 %), which is in striking contrast with the normally weakly luminescent Ag x Au 25Àx species (x = 1-12, QY = 0.21 %). X-ray crystallography further determines the substitution sites of Ag atoms in the Ag x Au 25Àx cluster through partial occupancy analysis, which provides further insight into the mechanism of photoluminescence enhancement.Fluorescent nanomaterials are of major importance in many fields.[1-4] Different types of fluorescent nanomaterials have been developed, such as quantum dots (QDs), [5] lanthanide nanoparticles, [6,7] and carbon nanodots. [8,9] Metal nanoclusters (Ag, Au) have emerged as a new class of nanomaterial. [10][11][12][13][14][15][16][17][18][19][20][21][22][23] Compared to QDs, [24] Au and Ag nanoclusters (NCs) are more biocompatible and can be readily bioconjugated; other advantages include their extrememly small size, good photostability, and low toxicity; thus, fluorescent noble-metal NCs have been recognized as a promising candidate for cell labeling, biosensing, and photo-therapy applications. [25][26][27][28][29][30] However, a general issue lies in the lower quantum yield (QY) of metal NCs compared to QDs and organic dyes, which significantly limits the applications of metal NCs. Various approaches have been developed to synthesize noble metal NCs with enhanced fluorescence, for example: 1) engineering the particle surface by using different ligands, such as DHLA, [31] dendrimers, [32] polymers, [33] DNA, [34,35] peptides, and proteins; [36][37][38][39][40][41][42][43][44] 2) controlling the metal core size [45] or doping the core with other metal atoms. Doping atomically precise nanoclusters is highly desired and allows atomic-level insight into the origin of fluorescence, which is of major importance. [46,47] Recently, several doped gold NCs with conserved core size have been successfully synthesized; [48][49][50][51][52][53] however, these thiolate-protected nanoclusters, as well as the phosphine-protected gold NCs, [13,16,54] are of low fluorescence. Herein, we report the discovery of drastic fluorescence enhancement in gold nanoclusters doped with 13 Ag atoms. Interestingly, gold nanoclusters of the same structure, but doped with fewer Ag atoms, are only weakly fluorescent. Thus, the 13th Ag atom triggers strong fluorescence in the doped gold nanocluster.Two synthetic methods were devised for obtaining Agdoped, 25-metal-atom nanoclusters (see the Experimental Section and the Supporting Information for details). In the first route, polydisperse Au nanoparticles [16] were first made and then used as the precursors to react with an Ag I thiolate complex, which gave rise to Ag-doped gold nanocl...

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A 200‐fold Quantum Yield Boost in the Photoluminescence of Silver‐Doped Ag_xAu_25−x Nanoclusters: The 13 th Silver Atom Matters

et al. 2014

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“…We previously reported a facile strategy to synthesize photoluminescent, water-soluble Au and Ag NCs stabilized with dihydrolipic acid (DHLA) [11,12] . Interestingly, their photophysical properties are highly sensitive to protein adsorption.…”

Section: Protein Adsorption Changes the Photophysical Properties Of Fmentioning

confidence: 99%

Fluorescent nanoparticle interactions with biological systems: What have we learned so far?

Nienhaus

2015

SPIE Proceedings

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Fluorescent nanoparticles (NPs) are promising optical probes for biological and biomedical applications, thanks to their excellent photophysical properties, color tunability and facile bioconjugation. It still remains unclear, however, how fluorescent NPs behave in the complex biological environment. Our group has quantified interactions of different fluorescent NPs (i.e., semiconductor quantum dots and metal nanoclusters) with serum proteins and living cells by the combined use of different spectroscopic and microscopic techniques. Our studies show that (1) interactions with proteins may significantly alter the photophysical properties of the NPs as well as the responses of cells internalizing them; (2) protein surface charge distributions play an important role in the interactions of NPs with proteins and cells; (3) ultrasmall NPs (diameter less than 10 nm) show a cellular internalization behavior that is distinctly different from the one observed with larger particles (diameter ~100 nm).

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“…[4][5][6] Additionally, recent studies have demonstrated the usefulness of fluorescent AgNCs in biodetection and biological imaging. 7,8 Meanwhile, AgNCs have been shown to effectively inactivate bacteria and inhibit microbial growth, but the mechanism has yet to be sufficiently elucidated. 9 Therefore, fluorescent AgNCs hold great potential as novel optical probes and may find wide application in biological research.…”

Section: Introductionmentioning

confidence: 99%

Polyethyleneimine-capped silver nanoclusters for microRNA oligonucleotide delivery and bacterial inhibition

Du¹,

Yan²,

Liang³

et al. 2017

IJN

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Efficient and safe nonviral gene delivery systems are a prerequisite for the clinical application of therapeutic genes. In this paper, polyethyleneimine-capped silver nanoclusters (PEI-AgNCs) were prepared for the purpose of microRNA (miRNA) delivery. The resultant PEI-AgNCs were characterized by a photoluminescence assay and transmission electron microscopy. A cytotoxicity assay showed that PEI-AgNCs exhibit relatively low cytotoxicity. Interestingly, PEI-AgNCs were confirmed to transfect miRNA mimics more effectively than PEI in HepG2 and 293A cells. In this regard, hsa-miR-21 or hsa-miR-221 mimics (miR-21/221m) were transported into HepG2 cells by using PEI-AgNCs. The miR-21/221 expression was determined post-transfection by quantitative real-time polymerase chain reaction. Compared with the negative control, PEI-AgNCs/miR-21/221m groups exhibited higher miR-21/221 levels. In addition, AgNCs endow PEI with stronger antibacterial activity, and this advantage provided PEI-AgNCs the potential to prevent bacterial contamination during the transfection process. Furthermore, we showed that PEI-AgNCs are viable nanomaterials for plain imaging of the cells by laser scanning confocal microscopy, indicating great potential as an ideal fluorescent probe to track the transfection behavior. These results demonstrated that PEI-AgNCs are promising and novel nonviral vectors for gene delivery.

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Ultrasmall fluorescent silver nanoclusters: Protein adsorption and its effects on cellular responses

Cited by 128 publications

References 58 publications

A 200‐fold Quantum Yield Boost in the Photoluminescence of Silver‐Doped Ag_xAu_25−x Nanoclusters: The 13 th Silver Atom Matters

A 200‐fold Quantum Yield Boost in the Photoluminescence of Silver‐Doped Ag_xAu_25−x Nanoclusters: The 13 th Silver Atom Matters

Fluorescent nanoparticle interactions with biological systems: What have we learned so far?

Polyethyleneimine-capped silver nanoclusters for microRNA oligonucleotide delivery and bacterial inhibition

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Ultrasmall fluorescent silver nanoclusters: Protein adsorption and its effects on cellular responses

Cited by 128 publications

References 58 publications

A 200‐fold Quantum Yield Boost in the Photoluminescence of Silver‐Doped AgxAu25−x Nanoclusters: The 13 th Silver Atom Matters

A 200‐fold Quantum Yield Boost in the Photoluminescence of Silver‐Doped AgxAu25−x Nanoclusters: The 13 th Silver Atom Matters

Fluorescent nanoparticle interactions with biological systems: What have we learned so far?

Polyethyleneimine-capped silver nanoclusters for microRNA oligonucleotide delivery and bacterial inhibition

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Product

Resources

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A 200‐fold Quantum Yield Boost in the Photoluminescence of Silver‐Doped Ag_xAu_25−x Nanoclusters: The 13 th Silver Atom Matters

A 200‐fold Quantum Yield Boost in the Photoluminescence of Silver‐Doped Ag_xAu_25−x Nanoclusters: The 13 th Silver Atom Matters