Methods and Applications in Fluorescence最新文献

{"title":"Simultaneous effects of synthesis temperature and dopants on MgWO4 UC phosphors","authors":"M. Prasad, V. K. Rai","doi":"10.1088/2050-6120/ac6ab7","DOIUrl":"https://doi.org/10.1088/2050-6120/ac6ab7","url":null,"abstract":"A sequence of coactivated divalent-metal tungstate Er3+/Yb3+/Mn4+: MgWO4 phosphors have been successfully developed to study the effect of synthesis temperature on the crystal structure, surface morphology, fluorescence, temperature sensing and the dynamics involved in the processes. Upconversion (UC) intensity of the Er3+/Yb3+: MgWO4 phosphors increased by ∼109 and ∼778 times on increasing the synthesis temperature from 800 °C to 1000 °C and 1200 °C. UC intensity of the Er3+/Yb3+/Mn4+: MgWO4 phosphors has been significantly improved up to ∼90 times via charge compensation. The incorporation of Mn4+ in the Er3+/Yb3+ codoped crystal system shifted the UC spectra from sharp green peaks to broadband emission along with amended sensing abilities. The ratiometric techniques of thermally coupled stark sublevels of the Er3+ have been used to achieve a wide temperature range (300–623 K). The prepared nanophosphors show maximum absolute & relative sensitivities ∼25.86 × 10−3 K−1 @453 K and ∼10.39 × 10−3 K−1 @303 K respectively with an accuracy of ±0.42 K@303 K.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":"10 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41367522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thienoguanosine brightness in DNA duplexes is governed by the localization of its ππ* excitation in the lowest energy absorption band","authors":"Stefano Ciaco, Krishna Gavvala, V. Greiner, Viola Mazzoleni, P. Didier, M. Ruff, L. Martínez-Fernández, R. Improta, Y. Mély","doi":"10.1088/2050-6120/ac6ab6","DOIUrl":"https://doi.org/10.1088/2050-6120/ac6ab6","url":null,"abstract":"Thienoguanosine (thG) is an isomorphic fluorescent guanosine (G) surrogate, which almost perfectly mimics the natural G in DNA duplexes and may therefore be used to sensitively investigate for example protein-induced local conformational changes. To fully exploit the information given by the probe, we carefully re-investigated the thG spectroscopic properties in 12-bp duplexes, when the Set and Ring Associated (SRA) domain of UHRF1 flips its 5′ flanking methylcytosine (mC). The SRA-induced flipping of mC was found to strongly increase the fluorescence intensity of thG, but this increase was much larger when thG was flanked in 3′ by a C residue as compared to an A residue. Surprisingly, the quantum yield and fluorescence lifetime values of thG were nearly constant, regardless of the presence of SRA and the nature of the 3′ flanking residue, suggesting that the differences in fluorescence intensities might be related to changes in absorption properties. We evidenced that thG lowest energy absorption band in the duplexes can be deconvoluted into two bands peaking at ∼350 nm and ∼310 nm, respectively red-shifted and blue-shifted, compared to the spectrum of thG monomer. Using quantum mechanical calculations, we attributed the former to a nearly pure ππ* excitation localized on thG and the latter to excited states with charge transfer character. The amplitude of thG red-shifted band strongly increased when its 3′ flanking C residue was replaced by an A residue in the free duplex, or when its 5′ flanking mC residue was flipped by SRA. As only the species associated with the red-shifted band were found to be emissive, the highly unusual finding of this work is that the brightness of thG in free duplexes as well as its changes on SRA-induced mC flipping almost entirely depend on the relative population and/or absorption coefficient of the red-shifted absorbing species.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45986542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recent advances in near infrared upconverting nanomaterials for targeted photodynamic therapy of cancer","authors":"Carla Arnau del Valle, T. Hirsch, María J. Marín","doi":"10.1088/2050-6120/ac6937","DOIUrl":"https://doi.org/10.1088/2050-6120/ac6937","url":null,"abstract":"Photodynamic therapy (PDT) is a well-established treatment of cancer that uses the toxic reactive oxygen species, including singlet oxygen (1O2), generated by photosensitiser (PS) drugs following irradiation of a specific wavelength to destroy the cancerous cells and tumours. Visible light is commonly used as the excitation source in PDT, which is not ideal for cancer treatment due to its reduced tissue penetration, and thus inefficiency to treat deep-lying tumours. Additionally, these wavelengths exhibit elevated autofluorescence background from the biological tissues which hinders optical biomedical imaging. An alternative to UV–Vis irradiation is the use of near infrared (NIR) excitation for PDT. This can be achieved using upconverting nanoparticles (UCNPs) functionalised with photosensitiser drugs where UCNPs can be used as an indirect excitation source for the activation of PS drugs yielding to the production of singlet 1O2 following NIR excitation. The use of nanoparticles for PDT is also beneficial due to their tumour targeting capability, either passively via the enhanced permeability and retention (EPR) effect or actively via stimuli-responsive targeting and ligand-mediated targeting (i.e. using recognition units that can bind specific receptors only present or overexpressed on tumour cells). Here, we review recent advances in NIR upconverting nanomaterials for PDT of cancer with a clear distinction between those reported nanoparticles that could potentially target the tumour due to accumulation via the EPR effect (passive targeting) and nanoparticle-based systems that contain targeting agents with the aim of actively target the tumour via a molecular recognition process.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45270553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluorescent cysteine probe based on a signal amplification unit, a catalyzed hairpin assembly reaction and Förster resonance energy transfer","authors":"Sirirat Ouiganon, Chongdee Thammakhet-Buranachai, P. Thavarungkul, P. Kanatharana, C. Buranachai","doi":"10.1088/2050-6120/ac6664","DOIUrl":"https://doi.org/10.1088/2050-6120/ac6664","url":null,"abstract":"This work developed a sensitive DNA-based fluorescent probe comprising a cysteine binding unit and a signal amplification unit based on a catalyzed hairpin assembly (CHA) reaction. The cysteine binding unit comprises a homodimer of single-stranded DNA (ssDNA) rich in cytosine and held together by silver ions. In the presence of cysteine, the homodimer is disintegrated because of cysteine-silver binding that liberates the ssDNA, which drives the CHA reaction in the signal amplification unit. Förster resonance energy transfer (FRET) was used to report the generation of the amplified double-stranded DNA (dsDNA) product. Under the optimal conditions, the probe provided a good linearity (100–1200 nM), a good detection limit (47.8 ± 2.7 nM) and quantification limit (159.3 ± 5.3 nM), and a good sensitivity (1.900 ± 0.045 μM−1). The probe was then used to detect cysteine in nine real food supplement samples. All results provided good recoveries that are acceptable by the AOAC, indicating that it has potential for practical applications.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46475986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phasor-based multi-harmonic unmixing for in-vivo hyperspectral imaging","authors":"A. Vallmitjana, Paola Lepanto, F. Irigoín, Leonel Malacrida","doi":"10.1101/2022.03.31.486485","DOIUrl":"https://doi.org/10.1101/2022.03.31.486485","url":null,"abstract":"Hyperspectral imaging (HSI) is a paramount technique in biomedical science, however, unmixing and quantification of each spectral component is a challenging task. Traditional unmixing relies on algorithms that need spectroscopic parameters from the fluorescent species in the sample. The phasor-based multi-harmonic unmixing method requires only the empirical measurement of the pure species to compute the pixel-wise photon fraction of every spectral component. Using simulations, we demonstrate the feasibility of the approach for up to 5 components and explore the use of adding a 6th unknown component representing autofluorescence. The simulations show that the method can be successfully used in typical confocal imaging experiments (with pixel photon counts between 101 and 103). As a proof of concept, we tested the method in living cells, using 5 common commercial dyes for organelle labeling and we easily and accurately separate them. Finally, we challenged the method by introducing a solvatochromic probe, 6-Dodecanoyl-N,N-dimethyl-2-naphthylamine (LAURDAN), intended to measure membrane dynamics on specific subcellular membrane-bound organelles by taking advantage of the linear combination between the organelle probes and LAURDAN. We succeeded in monitoring the membrane order in the Golgi apparatus, Mitochondria, and plasma membrane in the same in-vivo cell and quantitatively comparing them. The phasor-based multi-harmonic unmixing method can help expand the outreach of HSI and democratize its use by the community for it does not require specialized knowledge.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42961900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of constituents present in smokeless tobacco (<i>Nicotiana tabacum)</i>using spectroscopic techniques.","authors":"Pratima Mishra, Rohit Kumar, Abhishek Dwivedi, Awadhesh Kumar Rai","doi":"10.1088/2050-6120/ac5e11","DOIUrl":"10.1088/2050-6120/ac5e11","url":null,"abstract":"<p><p>Laser-Induced Breakdown Spectroscopy (LIBS) is an analytical technique used to identify and quantify the elements present in any type of material present in any phase (solid, liquid, gas, and aerosol). In the present work, our objective is to find the presence of toxic and other elements in chewing tobacco (<i><b>Nicotiana tabacum</b></i>) using LIBS. Spectral signatures of elements like C, Fe, Si, Mg, Mn, Ca, Ti, Na, H, N, K, O, along with some toxic elements Al, Sr, Li, Cu, Sb, and Cr are observed in the LIBS spectra of these tobacco samples. The spectral intensity ratio is measured for quantitative analysis of elements present in the samples. Further, Atomic Absorption Spectroscopy is used for determining absolute concentration in these samples. A relation between the AAS result and the relative intensity of spectral lines measured in the LIBS is obtained using regression analysis. The multivariate technique, Principal Component Analysis (PCA), discriminates all the samples based on their toxicity and other constituents. Molecular study (Photoacoustic spectroscopy (PAS), UV-Visible (UV-vis), and FT-IR) of tobacco samples were performed to analyze the molecules present in the tobacco samples.</p>","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":"10 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2022-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60498616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lifetime based axial contrast enable simple 3D-STED imaging","authors":"Yuanqing Ma, Alex Macmillan, Ying Yang, K. Gaus","doi":"10.1088/2050-6120/ac5e10","DOIUrl":"https://doi.org/10.1088/2050-6120/ac5e10","url":null,"abstract":"Stimulated Emission Depletion (STED) microscopy increase spatial image resolution by laterally sharpening the illumination profile of the confocal microscope. However, it remains compromised in axial resolution. To improve axial STED resolution, constructive interference of the STED depletion beam must be formed surrounding the focal plane to turn off the fluorophores beyond the focal plane. For isotropic 3D-STED resolution, this axial STED interference pattern must be overlayed with the doughnut STED beam at nanometer accuracy. Such optical configurations can be challenging in alignment. In this current work, we introduced a straightforward lifetime based axial contrast in STED microscope by imaging the samples on an ITO coated glass coverslip. The STED laser generates surface plasmon resonance on the ITO surface that enhanced the metal induced energy transfer MIET effect on the ITO surface. The enhanced MIET effect established a lifetime gradient with ∼20% dynamic range that extend for mor than 400 nm from the ITO surface. The axial contrast based on the lifetime gradient was directly used for 3D-STED imaging of tubulin fibers inside COS-7 cells, where the vertical displacement of single tubulin fiber was revealed. Lifetime gating could be applied to further improve lateral spatial resolution. Considering that most common implementation of STED microscopes uses pulsed lasers and timing electronics, there is no optical modification of the microscope is required in the current 3D-STED approach.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42305795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microwave-assisted synthesis and upconversion luminescence of NaYF4:Yb, Gd, Er and NaYF4:Yb, Gd, Tm nanorods.","authors":"Shivanand H Nannuri,&nbsp;Simranjit Singh,&nbsp;Superb K Misra,&nbsp;Santhosh C,&nbsp;Sajan D George","doi":"10.1088/2050-6120/ac58e6","DOIUrl":"https://doi.org/10.1088/2050-6120/ac58e6","url":null,"abstract":"<p><p>Anisotropic rare earth ion (RE³⁺) doped fluoride upconversion particles are emerging as potential candidate in diverse areas, ranging from biomedical imaging to photonics. Here, we develop a facile strategy to synthesize NaYF₄: Yb, Gd, Er, and NaYF₄: Yb, Gd, Tm upconversion nanorods via microwave synthesis route by controlling the synthesis time and compared the optical properties similar nanorods prepared via solvothermal technique. With the increase in synthesis time, the phase of the particle found to change from mixed phase to purely hexagonal and morphology of the particles change mixed phase of spherical and rod-shaped particles to completely nanorods for a synthesis time of 60 min. Further, the intrinsically hydrophobic particles changed to hydrophilic by removal of oleic capping via acid treatment and the amine functionalized silica coating. The upconversion luminescence as well as laser power dependent emission properties of the surface modified particles elucidate that surface modification route influence the upconversion luminescence as well as solvent dependent emission properties. Moreover, the laser power dependent studies elucidate that the upconversion process in a multi-photon process.</p>","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":"10 2","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39822539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced fluorescence from semiconductor quantum dot-labelled cells excited at 280 nm.","authors":"Mollie McFarlane,&nbsp;Nicholas Hall,&nbsp;Gail McConnell","doi":"10.1088/2050-6120/ac5878","DOIUrl":"https://doi.org/10.1088/2050-6120/ac5878","url":null,"abstract":"<p><p>Semiconductor quantum dots (QDs) have significant advantages over more traditional fluorophores used in fluorescence microscopy including reduced photobleaching, long-term photostability and high quantum yields, but due to limitations in light sources and optics, are often excited far from their optimum excitation wavelengths in the deep-UV. Here, we present a quantitative comparison of the excitation of semiconductor QDs at a wavelength of 280 nm, compared to the longer wavelength of 365 nm, within a cellular environment. We report increased fluorescence intensity and enhanced image quality when using 280 nm excitation compared to 365 nm excitation for cell imaging across multiple datasets, with a highest average fluorescence intensity increase of 3.59-fold. We also find no significant photobleaching of QDs associated with 280 nm excitation and find that on average, ∼80% of cells can tolerate exposure to high-intensity 280 nm irradiation over a 6-hour period.</p>","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":"10 2","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39648379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of synthesis temperature effect on β-NaGdF4: Yb3+, Er3+ upconversion luminescence efficiency and decay time using maximum entropy method","authors":"D. Pominova, I. Romanishkin, V. Proydakova, S. Kuznetsov, P. Grachev, A. Ryabova, N. Tabachkova, P. Fedorov, V. Loschenov","doi":"10.1088/2050-6120/ac5bdc","DOIUrl":"https://doi.org/10.1088/2050-6120/ac5bdc","url":null,"abstract":"Upconversion materials have several advantages for many applications due to their great potential in converting infrared light to visible. For practical use, it is necessary to achieve high intensity of UC luminescence, so the studies of the optimal synthesis parameters for upconversion nanoparticles are still going on. In the present work, we analyzed the synthesis temperature effect on the efficiency and luminescence decay of β-NaGd0.78Yb0.20Er0.02F4 (15–25 nm) upconversion nanoparticles with hexagonal crystal structure synthesized by anhydrous solvothermal technique. The synthesis temperature was varied in the 290 °C–320 °C range. The synthesis temperature was shown to have a significant influence on the upconversion luminescence efficiency and decay time. The coherent scattering domain linearly depended on the synthesis temperature and was in the range 13.1–22.3 nm, while the efficiency of the upconversion luminescence increases exponentially from 0.02 to 0.10% under 1 W cm−2 excitation. For a fundamental analysis of the reasons for the upconversion luminescence intensity dependence on the synthesis temperature, it was proposed to use the maximum entropy method for luminescence decay kinetics processing. This method does not require a preliminary setting of the number of exponents and, due to this, makes it possible to estimate additional components in the luminescence decay kinetics, which are attributed to different populations of rare-earth ions in different conditions. Two components in the green luminescence and one component in the red luminescence decay kinetics were revealed for nanoparticles prepared at 290 °C–300 °C. An intense short and a weak long component in green luminescence decay kinetics could be associated with two different populations of ions in the surface quenching layer and the crystal core volume. With an increase in the synthesis temperature, the second component disappears, and the decay time increases due to an increase in the number of ions in the crystal core volume and a more uniform distribution of dopants.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44254974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}