The oxygen evolution reaction (OER) is of great importance for renewable energy conversion and storage; however, the intrinsic process is sluggish and suffers from severe efficiency loss as well as ...large overpotentials. In this work, with the introduction of the plasmonic effects by design of the Au‐MnO2 hybrid catalysts, it is demonstrated that this photophysical phenomenon could largely promote the confinement of the outer electrons of Mn cations by plasmonic “hot holes” generated on gold surface. These “hot holes” work as the effective electron trapper to form the active Mnn+ species which could provide active sites to extract electrons from OH− and eventually facilitate the electrochemical OER catalysis under low laser power. By tuning the laser intensity from 100 to 200 mW, the overpotential is decreased from 0.38 to 0.32 V, which is comparable to IrO2 and RuO2 catalysts. These findings may provide insights into activation of plasmon‐promoted electrocatalysis under low power laser irradiation/treatment and the design of novel composite electrocatalysts.
A plasmon‐promoted electrochemical catalyst for oxygen evolution reaction (OER) is developed by integrating gold nanoantennas with MnO2 nanosheets. This work provides new insights into understanding light‐promoted electrochemical OER catalysis and sheds light on developing new plasmonic electrocatalysts under low power laser or sunlight irradiation.
Collagen’s long half-life (in skin approximately 10 years) makes this protein highly susceptible to glycation and formation of the advanced glycation end products (AGEs). Accumulation of ...cross-linking AGEs in the skin collagen has several detrimental effects; thus, the opportunity for non-invasive monitoring of skin glycation is essential, especially for diabetic patients. In this paper, we report using the time-resolved intrinsic fluorescence of collagen as a biomarker of its glycation. Contrary to the traditional fluorescence intensity decay measurement at the arbitrarily selected excitation and detection wavelengths, we conducted systematic wavelength- and time-resolved measurements to achieve time-resolved emission spectra. Changes in the intrinsic fluorescence kinetics, caused by both collagen aggregation and glycation, have been detected.
The application of time-resolved fluorescence sensing to the study of heterogenic biomolecular systems remains challenging because of the complexity of the resulting photophysics. Measuring the ...time-resolved emission spectroscopy (TRES) spectra can provide a more informative alternative to the modeling of the fluorescence decay that is currently employed. Here, we demonstrate this approach by monitoring real-time changes in intrinsic insulin fluorescence by TRES as a straightforward probe to directly measure kinetics of insulin aggregation and glycation. Our findings hold promise for monitoring the storage of insulin and its application in the control of diabetes and may support the development of more effective therapeutics against amyloidosis.
We report the effects of quercetin, a flavonoid present in the human diet, on early stage beta-amyloid (Aβ) aggregation, a seminal event in Alzheimer’s disease. Molecular level changes in Aβ ...arrangements are monitored by time-resolved emission spectral (TRES) measurements of the fluorescence of Aβ’s single tyrosine intrinsic fluorophore (Tyr). The results suggest that quercetin binds β-amyloid oligomers at early stages of their aggregation, which leads to the formation of modified oligomers and hinders the creation of β-sheet structures, potentially preventing the onset of Alzheimer’s disease.
We performed time-resolved transient absorption and fluorescence anisotropy measurements in order to study tautomerization of porphycene in rigid polymer matrices at cryogenic temperatures. Studies ...were carried out in poly(methyl methacrylate) (PMMA), poly(vinyl butyral) (PVB), and poly(vinyl alcohol) (PVA). The results prove that in all studied media hydrogen tunnelling plays a significant role in the double hydrogen transfer which becomes very sensitive to properties of the environment below approx. 150 K. We also demonstrate that there exist two populations of porphycene molecules in rigid media: "hydrogen-transferring" molecules, in which tautomerization occurs on time scales below 1 ns and "frozen" molecules in which double hydrogen transfer is too slow to be monitored with nanosecond techniques. The number of "frozen" molecules increases when the sample is cooled. We explain this effect by interactions of guest molecules with a rigid host matrix which disturbs symmetry of porphycene and hinders tunnelling. Temperature dependence of the number of hydrogen-transferring molecules suggests that the factor which restores the symmetry of the double-minimum potential well in porphycene are intermolecular vibrations localized in separated regions of the amorphous polymer.
Time-resolved studies of the double hydrogen transfer in porphycene indicate strong coupling of the reaction to the dynamics of the local microenvironment.
We investigate the nanometrology of sub-nanometre particle sizes in industrially manufactured sodium silicate liquors at high pH using time-resolved fluorescence anisotropy. Rather than the previous ...approach of using a single dye label, we investigate and quantify the advantages and limitations of multiplexing two fluorescent dye labels. Rotational times of the non-binding rhodamine B and adsorbing rhodamine 6G dyes are used to independently determine the medium microviscosity and the silicate particle radius, respectively. The anisotropy measurements were performed on the range of samples prepared by diluting the stock solution of silicate to concentrations ranging between 0.2 M and 2 M of NaOH and on the stock solution at different temperatures. Additionally, it was shown that the particle size can also be measured using a single excitation wavelength when both dyes are present in the sample. The recovered average particle size has an upper limit of 7.0 ± 1.2 Å. The obtained results were further verified using small-angle X-ray scattering, with the recovered particle size equal to 6.50 ± 0.08 Å. To disclose the impact of the dye label on the measured complex size, we further investigated the adsorption state of rhodamine 6G on silica nanoparticles using molecular dynamics simulations, which showed that the size contribution is strongly impacted by the size of the nanoparticle of interest. In the case of the higher radius of curvature (less curved) of larger particles, the size contribution of the dye label is below 10%, while in the case of smaller and more curved particles, the contribution increases significantly, which also suggests that the particles of interest might not be perfectly spherical.
Previously we have demonstrated surface plasmon enhanced energy transfer between fluorophores and gold nanorods under two-photon excitation using fluorescence lifetime imaging microscopy (FLIM) in ...both solution and intracellular phases. These studies demonstrated that gold nanoparticle-dye energy transfer combinations are appealing, not only in
Förster resonance energy transfer (FRET)
imaging, but also energy transfer-based fluorescence lifetime sensing of bio-analytes. Here, we apply this approach to study the internalization of gold nanorods (GNRs) in HeLa cells using the early endosome labeling marker GFP. The observed energy transfer between GFP and the GNRs indicates the involvement of endocytosis in GNR uptake. Moreover, a novel nanoprobe based on oligonucleotide functionalized gold nanorods for nucleic acid sensing
via
dye-GNRs energy transfer is demonstrated, potentially opening up new possibilities in cancer diagnosis and prognosis. The influence of oligonucleotide design on such nanoprobe performance was studied for the first time using time-resolved fluorescence spectroscopy, bringing new insights to the optimization of the nanoprobe.
Fluorescence Guided Surgery Stewart, Hazel L; Birch, David J S
Methods and applications in fluorescence,
10/2021, Letnik:
9, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Abstract
Fluorescence guided surgery (FGS) is an imaging technique that allows the surgeon to visualise different structures and types of tissue during a surgical procedure that may not be as visible ...under white light conditions. Due to the many potential advantages of fluorescence guided surgery compared to more traditional clinical imaging techniques such as its higher contrast and sensitivity, less subjective use, and ease of instrument operation, the research interest in fluorescence guided surgery continues to grow over various key aspects such as fluorescent probe development and surgical system development as well as its potential clinical applications. This review looks to summarise some of the emerging opportunities and developments that have already been made in fluorescence guided surgery in recent years while highlighting its advantages as well as limitations that need to be overcome in order to utilise the full potential of fluorescence within the surgical environment.
Gold nanorods (GNRs) have emerged as the most efficient photothermal agent in cancer therapy and photocatalysis. Understanding the influence of the surrounding medium, particle size, and excitation ...wavelength is critical to optimising the photothermal conversion rate. Here, three pairs of large and small gold nanorods of different aspect ratios and their heat generation under laser radiation at on and off surface plasmon resonance wavelengths in aqueous solution and gel‐like media are investigated. In the aqueous solution, the temperature rise of the large gold nanorods is more than with small gold nanorods at resonance excitation. In contrast to the large gold nanorods (LGNRs), the small gold nanorods (SGNRs) were less sensitive to excitation wavelength. At off‐resonance excitation, the temperature rise of the SGNRs is larger than that of the LGNRs. In the agarose gel, the photothermal effect of the SGNRs is greater than LGNRs excited at the wavelength near their solution phase longitudinal surface plasmon resonance wavelength. The temperature increase of LGNRs in gel is significantly less than in aqueous solution. These findings suggest that SGNRs could be more beneficial than the LGNRs for photothermal applications in biological systems and provides further insight when selecting GNRs.
Photothermal effect of large and small gold nanorods of different aspect ratios have been investigated at on and off surface plasmon resonance wavelengths in solution and gel media. In contrast to large gold nanorods, small gold nanorods were less sensitive to the excitation wavelength. This leads to more enhanced heat generation of small gold nanorods in gel media as surface plasmon resonance wavelength shifts when gold nanorods change media from water to gel.
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