Pub Date : 2022-05-18DOI: 10.1088/2050-6120/ac7123
Han Dong, Mogos Girmatsion, Ruoyu Wang, Gang Lu, Yunfei Xie, Yahui Guo, H. Qian, Weirong Yao
Chemical pollutants such as heavy metals and antibiotics in the environment pose a huge threat to humans and animals. Our studies have demonstrated that the fluorescence of phycocyanin showed quenching responses towards both mercury (Hg2+) and ciprofloxacin (CIP), which acted in accordance with the ‘OR’ molecular logic gate. In order to discriminate Hg2+ and CIP in application scenarios, cysteine (Cys) was utilized to design another ‘INHIBIT’ logic gate, in which Hg2+ and Cys were the two inputs. Thus, an intelligent biosensor with dual-target identification capacity was successfully developed by using a fluorescent natural protein in an ingenious logic gate system.
{"title":"Construction of fluorescent logic gates for the detection of mercury(II) and ciprofloxacin based on phycocyanin","authors":"Han Dong, Mogos Girmatsion, Ruoyu Wang, Gang Lu, Yunfei Xie, Yahui Guo, H. Qian, Weirong Yao","doi":"10.1088/2050-6120/ac7123","DOIUrl":"https://doi.org/10.1088/2050-6120/ac7123","url":null,"abstract":"Chemical pollutants such as heavy metals and antibiotics in the environment pose a huge threat to humans and animals. Our studies have demonstrated that the fluorescence of phycocyanin showed quenching responses towards both mercury (Hg2+) and ciprofloxacin (CIP), which acted in accordance with the ‘OR’ molecular logic gate. In order to discriminate Hg2+ and CIP in application scenarios, cysteine (Cys) was utilized to design another ‘INHIBIT’ logic gate, in which Hg2+ and Cys were the two inputs. Thus, an intelligent biosensor with dual-target identification capacity was successfully developed by using a fluorescent natural protein in an ingenious logic gate system.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43880530","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}
Pub Date : 2022-05-17DOI: 10.1088/2050-6120/ac70ab
Vishab Kesarwani, V. K. Rai
The present article reports the optical absorption and upconversion (UC) studies of 1.0 mol% Er3+/2.0 mol% Yb3+ doped/codoped glasses prepared by melt-quenching technique. The elements present and the composition of the prepared glass have been confirmed from XPS and XRF analysis respectively. Judd-Ofelt intensity parameters have been calculated using the absorption spectrum which is further utilized to predict the nature of Er_O bond, the transition probabilities, branching ratios and radiative lifetimes. The CIE study shows non-colour tunable and highly pure green emission (94.2%). The temperature-dependent UC emission spectra of the 2.0 mol% Yb3+ sensitized glass have been recorded at three different pump power densities to establish a reliable FIR based temperature scale. Furthermore, the Arrhenius fitting of the temperature-dependent spectra reveals low thermal quenching of green luminescence in the codoped glass.
{"title":"Fluorescence intensity ratio technique and its reliability","authors":"Vishab Kesarwani, V. K. Rai","doi":"10.1088/2050-6120/ac70ab","DOIUrl":"https://doi.org/10.1088/2050-6120/ac70ab","url":null,"abstract":"The present article reports the optical absorption and upconversion (UC) studies of 1.0 mol% Er3+/2.0 mol% Yb3+ doped/codoped glasses prepared by melt-quenching technique. The elements present and the composition of the prepared glass have been confirmed from XPS and XRF analysis respectively. Judd-Ofelt intensity parameters have been calculated using the absorption spectrum which is further utilized to predict the nature of Er_O bond, the transition probabilities, branching ratios and radiative lifetimes. The CIE study shows non-colour tunable and highly pure green emission (94.2%). The temperature-dependent UC emission spectra of the 2.0 mol% Yb3+ sensitized glass have been recorded at three different pump power densities to establish a reliable FIR based temperature scale. Furthermore, the Arrhenius fitting of the temperature-dependent spectra reveals low thermal quenching of green luminescence in the codoped glass.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":"10 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60499051","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}
Pub Date : 2022-05-17DOI: 10.1088/2050-6120/ac70aa
J. Schuyt, G. Williams, K. Shinohara, T. Shimizu, K. Yamanoi, M. Cadatal-Raduban
The luminescence properties of NaMgF3:Sm and NaMgF3:Ce,Sm were studied in the vacuum ultraviolet spectral region. Excitation bands corresponding to the charge transfer processes F− → Sm3+, O2− → Sm3+, and O2− → Ce3+, and the energy transfer processes Ce3+ → Sm3+ and O2− → Sm3+, were observed. The energies of the Sm3+ charge transfer transitions and the crystal field split Ce3+ 4f 05d 1 transitions were used to construct a complete host referred binding energy diagram for the series of lanthanide-doped NaMgF3:Ln compounds. We demonstrate that the optical and luminescence properties predicted by the binding energy diagram are in good agreement with those predicted by the binding energy diagram constructed via the alternative impurity-informed method, and all available experimental data regarding the NaMgF3:Ln compounds. We demonstrate that NaMgF3:Ln compounds are model systems for the study of charge trapping phenomena and divalent lanthanide luminescence. Ultimately, we validate that the impurity-informed method can be used to establish the energy levels of lanthanides in fluoride systems.
{"title":"Vacuum ultraviolet photoluminescence of NaMgF3:Sm and NaMgF3:Sm,Ce: energy levels of the lanthanides in NaMgF3:Ln compounds","authors":"J. Schuyt, G. Williams, K. Shinohara, T. Shimizu, K. Yamanoi, M. Cadatal-Raduban","doi":"10.1088/2050-6120/ac70aa","DOIUrl":"https://doi.org/10.1088/2050-6120/ac70aa","url":null,"abstract":"The luminescence properties of NaMgF3:Sm and NaMgF3:Ce,Sm were studied in the vacuum ultraviolet spectral region. Excitation bands corresponding to the charge transfer processes F− → Sm3+, O2− → Sm3+, and O2− → Ce3+, and the energy transfer processes Ce3+ → Sm3+ and O2− → Sm3+, were observed. The energies of the Sm3+ charge transfer transitions and the crystal field split Ce3+ 4f 05d 1 transitions were used to construct a complete host referred binding energy diagram for the series of lanthanide-doped NaMgF3:Ln compounds. We demonstrate that the optical and luminescence properties predicted by the binding energy diagram are in good agreement with those predicted by the binding energy diagram constructed via the alternative impurity-informed method, and all available experimental data regarding the NaMgF3:Ln compounds. We demonstrate that NaMgF3:Ln compounds are model systems for the study of charge trapping phenomena and divalent lanthanide luminescence. Ultimately, we validate that the impurity-informed method can be used to establish the energy levels of lanthanides in fluoride systems.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48439118","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}
Pub Date : 2022-05-11DOI: 10.1088/2050-6120/ac6ecb
Ádám Golcs, Korinna Kovács, Panna Vezse, L. Bezúr, P. Huszthy, T. Tóth
We report here the development of a surface-modified quartz glass sheet, which affords an opportunity for converting conventional spectrofluorometers to ion-selective optochemical sensors by placing it diagonally into a photometric cuvette. Moreover, we describe a generalizable technique, which allows the usage of any polymerizable ionophores for developing multiple-use fluorescent chemosensors of various selectivity. A fluorescent bis(acridino)-crown ether containing allyl groups was photocatalytically copolymerized with a methacrylate-acrylamide-based monomer mixture to obtain an ion-selective sensor membrane layer on the surface of the cuvette-compatible glass sheet. This glass membrane-based direct optode enabled the analysis of Zn2+ above a lower limit of detection of 2.2 × 10–7 mol·l−1 with an excellent reusability. Limiting factors, like pH and competing ionic or organic agents were thoroughly investigated. Moreover, spiked river-water samples were measured to demonstrate applicability. The proposed sensor placed in any conventional spectrofluorometer provides an innovative method for perturbation-free analysis of Zn2+ for all the chemists in need of a fast, easy-to-use, portable and regenerable analyzer without the requirement of an analyte-specific instrumentation.
{"title":"A cuvette-compatible Zn2+ sensing tool for conventional spectrofluorometers prepared by copolymerization of macrocyclic fluoroionophores on quartz glass surface","authors":"Ádám Golcs, Korinna Kovács, Panna Vezse, L. Bezúr, P. Huszthy, T. Tóth","doi":"10.1088/2050-6120/ac6ecb","DOIUrl":"https://doi.org/10.1088/2050-6120/ac6ecb","url":null,"abstract":"We report here the development of a surface-modified quartz glass sheet, which affords an opportunity for converting conventional spectrofluorometers to ion-selective optochemical sensors by placing it diagonally into a photometric cuvette. Moreover, we describe a generalizable technique, which allows the usage of any polymerizable ionophores for developing multiple-use fluorescent chemosensors of various selectivity. A fluorescent bis(acridino)-crown ether containing allyl groups was photocatalytically copolymerized with a methacrylate-acrylamide-based monomer mixture to obtain an ion-selective sensor membrane layer on the surface of the cuvette-compatible glass sheet. This glass membrane-based direct optode enabled the analysis of Zn2+ above a lower limit of detection of 2.2 × 10–7 mol·l−1 with an excellent reusability. Limiting factors, like pH and competing ionic or organic agents were thoroughly investigated. Moreover, spiked river-water samples were measured to demonstrate applicability. The proposed sensor placed in any conventional spectrofluorometer provides an innovative method for perturbation-free analysis of Zn2+ for all the chemists in need of a fast, easy-to-use, portable and regenerable analyzer without the requirement of an analyte-specific instrumentation.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48692897","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}
Pub Date : 2022-05-11DOI: 10.1088/2050-6120/ac6eca
R. Shanmugapriya, P. S. Kumar, C. Nandhini, K. Satheeshkumar, K. Vennila, K. Elango
A highly selective and sensitive assay of Al(III) using ratiometric fluorescence enhancement is reported in an aqueous solution. The probe (named RS5) exhibits a red-shift of 54 nm upon binding with Al(III) ion. The significant enhancement response of RS5 at 481 nm is attributed to the formation of a 1:1 complex between the probe and Al(III), wherein RS5 acts as a tridentate NNN-donor ligand. The complexation process is ascertained by 1H, 13C, and 27Al NMR and HR-MS spectral techniques. The binding constant of the complex is determined to be 1.3 × 105 M−1. The ratiometric change in fluorescence upon complexation with Al(III) is ascribed to an increase in intramolecular charge transfer (ICT) transition along with chelation enhanced fluorescence (CHEF) processes. The probe can be applied for monitoring Al(III) in a pH range of 6–8. The limit of detection (LOD) of RS5 for the examination of Al(III) is found to be 0.3 μM. With an aim to understand the sensing behavior of RS5, the optical properties of the probe and its Al(III) complex are investigated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The probe is successfully employed for the determination of Al(III), with very high recovery percentages, in natural matrices like deep well water, tap water, drinking water, pond water, river water, bovine serum albumin (BSA) solution and blood serum.
{"title":"A highly selective and sensitive ratiometric fluorescent probe for quantitative detection of Al(III) in different natural matrices","authors":"R. Shanmugapriya, P. S. Kumar, C. Nandhini, K. Satheeshkumar, K. Vennila, K. Elango","doi":"10.1088/2050-6120/ac6eca","DOIUrl":"https://doi.org/10.1088/2050-6120/ac6eca","url":null,"abstract":"A highly selective and sensitive assay of Al(III) using ratiometric fluorescence enhancement is reported in an aqueous solution. The probe (named RS5) exhibits a red-shift of 54 nm upon binding with Al(III) ion. The significant enhancement response of RS5 at 481 nm is attributed to the formation of a 1:1 complex between the probe and Al(III), wherein RS5 acts as a tridentate NNN-donor ligand. The complexation process is ascertained by 1H, 13C, and 27Al NMR and HR-MS spectral techniques. The binding constant of the complex is determined to be 1.3 × 105 M−1. The ratiometric change in fluorescence upon complexation with Al(III) is ascribed to an increase in intramolecular charge transfer (ICT) transition along with chelation enhanced fluorescence (CHEF) processes. The probe can be applied for monitoring Al(III) in a pH range of 6–8. The limit of detection (LOD) of RS5 for the examination of Al(III) is found to be 0.3 μM. With an aim to understand the sensing behavior of RS5, the optical properties of the probe and its Al(III) complex are investigated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The probe is successfully employed for the determination of Al(III), with very high recovery percentages, in natural matrices like deep well water, tap water, drinking water, pond water, river water, bovine serum albumin (BSA) solution and blood serum.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43641658","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}
A novel fluorescence sensor for successive detection of Cu2+ and Fe3+ based on anti-B18H22 derivative which possesses 5-hydroxyisoquinoline as an ionophore was synthesized via a one-pot and its structure and photophysical properties were characterized by NMR, HRMS, FTIR, UV–vis, PL and theoretical calculation. The fluorophore displays two emission peaks at 460 nm and 670 nm in THF solution coming from the emission of the locally excited state and intramolecular charge transfer fluorescence, respectively. The complex exhibited obvious aggregation-induced emission enhancement (AIEE) characteristics in THF/H2O solution by increasing the aqueous concentration from 70% to 95%. The AIEE molecules showed a high selectivity towards Cu2+ over other metal ions by forming a 2:1 metal-to-ligand complex in THF/H2O (fw = 20%) solution, the fluorescence intensity increased as a linear function of the Cu2+ concentration at 460 nm due to the inhibition of PET effect. The fluorescent emission was quenched linearly by the addition of Fe3+, which provides a method for successive determination of Cu2+ and Fe3+ based on ‘off-on-off’ fluorescence of the fluorescent. The detection limit of Cu2+ and Fe3+ was 5.7 × 10−6 M and 7.2 × 10−5 M respectively. Morever, a rapid identification of Cu2+ in the aqueous solution by naked eyes can be realized. In addition, the molecules were pH-sensitive, the fluorescence quenching can be observed in strongly alkaline environment. The method has been applied to the determination of copper ions in water samples with satisfactory results.
{"title":"A novel AIEE active anti-B18H22 derivative-based Cu2+ and Fe3+ fluorescence off-on-off sensor","authors":"Linli Xiong, Yong Zheng, Haibo Wang, Jiangyang Yan, Xuguang Huang, Hongyun Meng, Chunhua Tan","doi":"10.1088/2050-6120/ac6b88","DOIUrl":"https://doi.org/10.1088/2050-6120/ac6b88","url":null,"abstract":"A novel fluorescence sensor for successive detection of Cu2+ and Fe3+ based on anti-B18H22 derivative which possesses 5-hydroxyisoquinoline as an ionophore was synthesized via a one-pot and its structure and photophysical properties were characterized by NMR, HRMS, FTIR, UV–vis, PL and theoretical calculation. The fluorophore displays two emission peaks at 460 nm and 670 nm in THF solution coming from the emission of the locally excited state and intramolecular charge transfer fluorescence, respectively. The complex exhibited obvious aggregation-induced emission enhancement (AIEE) characteristics in THF/H2O solution by increasing the aqueous concentration from 70% to 95%. The AIEE molecules showed a high selectivity towards Cu2+ over other metal ions by forming a 2:1 metal-to-ligand complex in THF/H2O (fw = 20%) solution, the fluorescence intensity increased as a linear function of the Cu2+ concentration at 460 nm due to the inhibition of PET effect. The fluorescent emission was quenched linearly by the addition of Fe3+, which provides a method for successive determination of Cu2+ and Fe3+ based on ‘off-on-off’ fluorescence of the fluorescent. The detection limit of Cu2+ and Fe3+ was 5.7 × 10−6 M and 7.2 × 10−5 M respectively. Morever, a rapid identification of Cu2+ in the aqueous solution by naked eyes can be realized. In addition, the molecules were pH-sensitive, the fluorescence quenching can be observed in strongly alkaline environment. The method has been applied to the determination of copper ions in water samples with satisfactory results.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43138010","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}
Pub Date : 2022-04-28DOI: 10.1088/2050-6120/ac6b87
Dipti Bidwai, Niroj Kumar Sahu, S. J. Dhoble, Ashutosh Mahajan, D. Haranath, G. Swati
Semiconductor assisted photocatalysis is one of the most efficient methods for the degradation of complex organic dyes. A major limiting factor of semiconductor assisted photocatalysis is the requirement of a continuous source of light to perform a redox reaction. One of the upcoming solutions is photon energy-storing long afterglow/persistent phosphors. They are an unusual kind of rechargeable, photon energy capturing/trapping phosphors that can trap charge carriers (electrons/holes) in their meta-stable energy levels, thereby resulting in persistent luminescence. Persistence luminescence from such materials can range from minutes to hours. The coupling of long afterglow phosphors (LAP) with the conventional semiconductor is a promising way to support the photocatalytic process even in dark. In addition, dissimilar band structures of LAPs and semiconductor results in formation of heterojunction which further suppresses the recombination of charge. Such an encouraging idea of LAP for round-the-clock working photocatalytic system is in its premature stage; which is required to be investigated fully. Thus, we present a state-of-art review on the potential materials for assisting round-the-clock photocatalysis, trapping-detrapping mechanism in LAP materials, fabrication strategies and their associated characterization tools. Review also covers LAP materials and their photocatalytic mechanism briefly.
{"title":"Review on long afterglow nanophosphors, their mechanism and its application in round-the-clock working photocatalysis","authors":"Dipti Bidwai, Niroj Kumar Sahu, S. J. Dhoble, Ashutosh Mahajan, D. Haranath, G. Swati","doi":"10.1088/2050-6120/ac6b87","DOIUrl":"https://doi.org/10.1088/2050-6120/ac6b87","url":null,"abstract":"Semiconductor assisted photocatalysis is one of the most efficient methods for the degradation of complex organic dyes. A major limiting factor of semiconductor assisted photocatalysis is the requirement of a continuous source of light to perform a redox reaction. One of the upcoming solutions is photon energy-storing long afterglow/persistent phosphors. They are an unusual kind of rechargeable, photon energy capturing/trapping phosphors that can trap charge carriers (electrons/holes) in their meta-stable energy levels, thereby resulting in persistent luminescence. Persistence luminescence from such materials can range from minutes to hours. The coupling of long afterglow phosphors (LAP) with the conventional semiconductor is a promising way to support the photocatalytic process even in dark. In addition, dissimilar band structures of LAPs and semiconductor results in formation of heterojunction which further suppresses the recombination of charge. Such an encouraging idea of LAP for round-the-clock working photocatalytic system is in its premature stage; which is required to be investigated fully. Thus, we present a state-of-art review on the potential materials for assisting round-the-clock photocatalysis, trapping-detrapping mechanism in LAP materials, fabrication strategies and their associated characterization tools. Review also covers LAP materials and their photocatalytic mechanism briefly.","PeriodicalId":18596,"journal":{"name":"Methods and Applications in Fluorescence","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2022-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47808257","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}
Pub Date : 2022-04-26DOI: 10.1088/2050-6120/ac6ab7
M. Prasad, V. K. Rai
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.
{"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}
Pub Date : 2022-04-26DOI: 10.1088/2050-6120/ac6ab6
Stefano Ciaco, Krishna Gavvala, V. Greiner, Viola Mazzoleni, P. Didier, M. Ruff, L. Martínez-Fernández, R. Improta, Y. Mély
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.
{"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}
Pub Date : 2022-04-21DOI: 10.1088/2050-6120/ac6937
Carla Arnau del Valle, T. Hirsch, María J. Marín
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.
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