Protein-templated gold nanoclusters: size dependent inversion of fluorescence emission in the presence of molecular oxygen

Das, Tarasankar; Ghosh, Prasun; Shanavas, Muhammad Salman; Maity, Arnab; Mondal, Somen; Purkayastha, Pradipta

doi:10.1039/c2nr31271a

Cited by 66 publications

(50 citation statements)

References 60 publications

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“…The average particle size was found to be around 8 nm (Figure 2) with a narrow size distribution supporting the possibility of the presence of at least two BSA molecules holding gold cluster together. This observation is in well agreement with the report from Purkayastha et al 20 .…”

Section: Resultssupporting

confidence: 94%

Polarization properties of fluorescent BSA protected Au25 nanoclusters

et al. 2013

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BSA protected gold nanoclusters (Au25) are attracting great deal of attention due to their unique spectroscopic properties and possible use in biophysical applications. Although there are reports on synthetic strategies, spectroscopy and applications, little is known about their polarization behavior. In this study, we synthesized the BSA protected Au25 nanoclusters and studied their steady state and time resolved fluorescence properties including polarization behavior in different solvents: glycerol, propylene glycol and water. We demonstrated that the nanocluster absorption can be separated from the extinction spectrum by subtraction of Rayleigh scattering. The nanocluster absorption spectrum is well approximated by three Gaussian components. By a comparison of the emissions from BSA Au25 clusters and rhodamine B in water, we estimated the quantum yield of nanoclusters to be higher than 0.06. The fluorescence lifetime of the BSA Au25 cluster is long and heterogeneous with an average value of 1.84 μs. In glycerol at −20°C the anisotropy is high, reaching a value of 0.35. However, the excitation anisotropy strongly depends on the excitation wavelengths indicating a significant overlap of the different transition moments. The anisotropy decay in water reveals a correlation time below 0.2 μs. In propylene glycol the measured correlation time is longer and initial anisotropy depends on the excitation wavelength. The BSA Au25 cluster, due to long lifetime and high polarization, can potentially be used in studying large macromolecules such as protein complexes with large molecular weight.

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Section: Resultssupporting

confidence: 94%

Polarization properties of fluorescent BSA protected Au25 nanoclusters

et al. 2013

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“…The papers that reported synthesis using NaOH as a reducing agent [13,39] attribute a PL band around 470 nm to the PL of protein. Moreover, using mass spectroscopy Das et al demonstrated that performing the synthesis of BSA-Au NCs using NaOH as a reducing agent, only Au 25 nanoclusters were formed [40]. Both Au 8 and Au 25 nanoclusters were formed when a different reducing agent (ascorbic acid) was used.…”

Section: Discussionmentioning

confidence: 99%

Protein stabilized Au nanoclusters: spectral properties and photostability

Poderys¹,

Matulionytė-Safinė²,

Rupšys³

et al. 2016

Lith. J. Phys.

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Bovine serum albumin stabilized gold nanoclusters (BSA-Au nanoclusters) have been widely studied due to their possible applications in biomedicine as sensors, fluorescent or multi-modality markers, and therapeutic agents. Synthesis and optical properties of these nanoclusters have been extensively investigated; however, there is still very little data on photostability of BSA-Au nanoclusters. Photostability of BSA-Au nanoclusters is of major importance for a variety of applications, such as material sensing and fluorescence imaging. Herein we demonstrate that after synthesis the BSA-Au solution has two photoluminescence (PL) bands peaking at 468 and 660 nm. Nevertheless, a different behaviour of the PL bands at 468 and 660 nm upon irradiation indicates that only band at 660 nm is related to PL of Au nanoclusters. BSA-Au nanoclusters exhibit great colloidal stability and do not undergo irreversible changes when heated up to 65 °C. However, irradiation of BSA-Au nanoclusters causes a wavelength dependent decrease of intensity and a hypsochromic shift of the PL band at 660 nm which is proportional to the delivered dose. The shift of the PL band at 660 nm could occur due to loss of several gold atoms in Au nanoclusters and/or due to deterioration of a nanoparticle coating layer. We have also demonstrated that the photostability of BSA-Au nanoclusters increases in the cell growth medium.

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“…640 nm emission) was Au 25 NC (Figures 2c and 2d). 12a (Note: the “blue species” may alternatively be assigned to the oxidized product of Trp from BSA 15…”

Section: Protein‐directed Approachesmentioning

confidence: 99%

π‐Expanded α,β‐Unsaturated Ketones: Synthesis, Optical Properties, and Two‐Photon‐Induced Polymerization

et al. 2014

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A library of π-expanded α,β-unsaturated ketones was designed and synthesized. They were prepared by a combination of Wittig reaction, Sonogashira reaction, and aldol condensation. It was further demonstrated that the double aldol condensation can be performed effectively for highly polarized styrene- and diphenylacetylene-derived aldehydes. The strategic placement of two dialkylamino groups at the periphery of D-π-A-π-D molecules resulted in dyes with excellent solubility. These ketones absorb light in the region 400-550 nm. Many of them display strong solvatochromism so that the emission ranges from 530-580 nm in toluene to the near-IR region in benzonitrile. Ketones based on cyclobutanone as central moieties display very high fluorescence quantum yields in nonpolar solvents, which decrease drastically in polar media. Photophysical studies of these new functional dyes revealed that they possess an enhanced two-photon absorption cross section when compared with simpler ketone derivatives. Due to strong polarization of the resulting dyes, values of two-photon absorption cross sections on the level of 200-300 GM at 800 nm were achieved, and thanks to that as well as the presence of the keto group, these new two-photon initiators display excellent performance so that the operating region is 5-75 mW in some cases.

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Protein-templated gold nanoclusters: size dependent inversion of fluorescence emission in the presence of molecular oxygen

Cited by 66 publications

References 60 publications

Polarization properties of fluorescent BSA protected Au25 nanoclusters

Polarization properties of fluorescent BSA protected Au25 nanoclusters

Protein stabilized Au nanoclusters: spectral properties and photostability

π‐Expanded α,β‐Unsaturated Ketones: Synthesis, Optical Properties, and Two‐Photon‐Induced Polymerization

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