Methods and Applications in Fluorescence最新文献

Fluorescence spectroscopy serves as a vital technique for studying the interaction between light and fluorescent molecules. It encompasses a range of methods, each presenting unique advantages and applications. This technique finds utility in various chemical studies. This review discusses Fluorescence spectroscopy, its branches such as Time-Resolved Fluorescence Spectroscopy (TRFS) and Fluorescence Lifetime Imaging Microscopy (FLIM), and their integration with other spectroscopic methods, including Raman, Infrared (IR), and Circular Dichroism (CD) spectroscopies. By delving into these methods, we aim to provide a comprehensive understanding of the capabilities and significance of fluorescence spectroscopy in scientific research, highlighting its diverse applications and the enhanced understanding it brings when combined with other spectroscopic methods. This review looks at each technique's unique features and applications. It discusses the prospects of their combined use in advancing scientific understanding and applications across various domains.

Blinking of fluorophores is essential in the context of single molecule localization-based optical super-resolution microscopy methods. To make the fluorescence molecule undergo blinking specific complex chemical mounting buffer systems, combined with suitable oxygen scavengers, and reducing agents are required. For instance to realise blinking in widely used fluorescence tags, like Alexa Fluor 647 (AF647), they are to be mounted on anti-fading buffer such as Mowiol and reducing agent such as Beta (β) - ME. However, the quality of the super-resolved images is decided by the total number of blinking events or in other words net duration for which the fluorescence blinking persists. In this paper we investigate how a violet and UV light induced fluorescence recovery mechanism can enhance the duration of fluorescence blinking. Our study uses AF647 dye conjugated with Phalloidin antibody in U87MG cell line mounted on Mowiol andβ- ME. On the basis of the investigation we optimize the intensity, at the sample plane, of fluorescence excitation laser at 638 nm and fluorescence recovery beam at 405 nm or in the UV giving the maximum possible fluorescence blinking duration. We observe that the longer blinking duration, using the optimized illumination scheme, has brought down the resolution in the super-resolved image, as given by Fourier Ring Correlation method, from 168 nm to 112 nm, while the separation between two nearby resolvable filaments has been brought down to ≤ 60 nm.

In the past, there were limited efforts to use light-emitting diodes (LEDs) for pumping solid-state lasers. However, these attempts were overshadowed by the introduction of laser diodes, which offered more favourable pumping conditions. Nevertheless, recent advancements in high-power LEDs, coupled with the utilization of luminescent concentrators (LC), have paved the way for a novel approach to pump solid-state lasers. The combination of LEDs and LC in this LED-LC system presents several advantages, including enhanced ruggedness, stability, and cost-effectiveness compared to other laser pumping methods. This review explores the various techniques employed to pump solid-state lasers using LED-LC as a pump source, along with improvements made to enhance the brightness of LEDs in this context.

The alignment of chromophores plays a crucial role in determining the optoelectronic properties of materials. Such alignment can make interpretation of fluorescence anisotropy microscopy (FAM) images somewhat ambiguous. The time-resolved emission behaviour can also influence the fluorescence anisotropy. This is particularly the case when probing excitation energy migration between chromophores in a condensed phase. Ideally information concerning the chromophoric alignment, emission decay kinetics and fluorescence anisotropy can be recorded and correlated. We report on the use of polarised transmission imaging (PTI) coupled with both steady-state and time-resolved FAM to enable accurate identification of chromophoric alignment and morphology in thin films of a conjugated polydiarylfluorene. We show that the combination of these three imaging modes presents a comprehensive methodology for investigating the alignment and morphology of chromophores in thin films, particularly for accurately mapping the distribution of amorphous and crystalline phases within the thin films, offering valuable insights for the design and optimization of materials with enhanced optoelectronic performance.

This study evaluated the reliability of portable X-ray fluorescence (pXRF) in Pb²⁺adsorption kinetics and isotherm experiments using soybean straw biochar. The research aimed to compare pXRF results with those obtained through traditional atomic absorption spectrometry (AAS). Soybean straw biochar, produced at 400 °C, was employed as the adsorbent for Pb²⁺. The efficiency of adsorption was assessed using Langmuir and Freundlich models. The kinetics of Pb²⁺adsorption was analysed through pseudo-first-order and pseudo-second-order models. The pseudo-second-order model described the kinetics of Pb²⁺adsorption on biochar better than the pseudo-first order model. Importantly, the pXRF technique demonstrated comparable results to those of AAS, making it a reliable and resource-efficient method for studying Pb²⁺kinetics. The results of the isotherm analyses fit the Langmuir model, indicating a desirable and irreversible adsorption of Pb²⁺on biochar. PXRF measurements on biochar allowed simultaneous observations of Pb²⁺adsorption and K⁺and Ca²⁺desorption, highlighting ionic exchange as the primary adsorption mechanism. In conclusion, our results showcased the applicability of pXRF for Pb⁺²adsorption studies in biochars, offering a valuable alternative to traditional methods. The findings contribute to the understanding of biochar as an effective adsorbent for heavy metals, emphasizing the potential of pXRF for cost-effective and efficient environmental research. In this study, we present a novel and detailed procedure that will allow other researchers to continue their studies on Pb²⁺adsorption on biochar or similar matrices, significantly reducing the resources and time used and enabling the simultaneous study of the behavior of other ions participating in the process.

Lead halide perovskite nanocrystals (PNCs) have attracted intense attention due to their excellent optoelectronic properties. In this work, a series of water-stable CsPb(Br/I)₃PNCs fluorescent probes were prepared using an anion exchange method. It was found that the PNCs probes could be used to detect ascorbic acid (AA) in water, and interestingly, the FL spectra of the PNCs probes can be adjusted by controlling the concentration of KI in anion exchange to improve the detection selectivity of AA. The high sensitivity and selectivity make CsPb(Br/I)₃PNCs an ideal material for AA sensing. The concentration of AA can be linearly measured in the range from 0.01 to 50μM, with a detection limit of 4.2 nM. The reason for the enhanced FL of CsPb(Br/I)₃PNCs was studied, and it is considered that AA causes the aggregation of CsPb(Br/I)₃PNCs. This strategy of improving the selectivity of the probe to the substrate by adjusting the spectrum will significantly expand the application of PNCs in the field of analysis and detection.

Polycationic photosensitizers (PS) are not susceptible to aggregation in solutions, but their high local concentrations in Gram-negative bacteria can be sufficient for aggregation and reduced effectiveness of antibacterial photodynamic treatment. By measuring fluorescence spectra and kinetics we were able to evaluate the degree of aggregation of polycationic PS ZnPcChol₈in Gram-negative bacteria E.coliK12 TG1. Binding of ZnPcChol₈toE.coliK12 TG1 leads to an appearance of groups of molecules with shorter PS fluorescence lifetime, a decrease in fluorescence intensity and a shift in the fluorescence spectral maximum. However, we evaluated that about 88% of the fluorescing PS molecules in the bacteria were in an unaggregated state, which indicates only a small reduction in the generation of reactive oxygen species.

Lanthanide-doped fluoride nanocrystals (NCs) exhibit excellent optical features, including upconversion and downconversion luminescence (UCL and DCL), that can be utilized in a variety of applications. In this study, we have successfully demonstrated the photoluminescence behavior of triple-doped NaYF₄: Yb³⁺, Er³⁺, Pr³⁺NCs in the Vis-NIR region. Herein, highly monodisperse hexagonal phase NaYF₄: Yb_0.2, Er_0.02, Pr_xnanocrystals in various Pr³⁺(x = 0, 0.1, 0.5, and 1 mol %) concentration with ∼22 nm diameter synthesized by thermal decomposition technique. The photoluminescence studies for all samples were performed under 980 nm laser excitation. The luminescence intensity of Er³⁺including blue (407 nm), green (520 and 540 nm), red (654 nm), and near-infrared (845 nm and 1530 nm) emissions was significantly quenched and Pr³⁺emission intensity at 1290 nm (Pr³⁺:¹G₄→³H₅) changes irregularly upon doping with Pr³⁺ions. Furthermore, we performed the excitation power dependence and decay time analysis to investigate the energy transfer and upconversion mechanisms of samples. These findings indicate that the presence of praseodymium strongly reduces emission intensities due to abundant cross-relaxation channels. In addition, particle size is an efficient factor, shedding light on the influence of Pr³⁺on the energy transfer and upconversion mechanisms of the fluorides.