Browsing by Author "Arpita Dwivedi"

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A Eu3+doped functional core-shell nanophosphor as fluorescent biosensor for highly selective and sensitive detection of dsDNA
(Elsevier B.V., 2023) Arpita Dwivedi; Monika Srivastava; Amit Srivastava; Abhai Kumar; Rameshwar Nath Chaurasia; S.K. Srivastava
Lanthanide-doped core-shell nanomaterials have illustrated budding potential as luminescent materials, but their biological applications have still been very limited due to their aqueous solubility and biocompatibility. Here, we report a simple and cost-effective approach to construct a water-stable chitosan-functionalized lanthanoid-based core shell (Ca-Eu:Y2O3@SiO2) nanophosphor. The as-synthesized Ca-Eu:Y2O3@SiO2-chitosan (CEY@SiO2-CH) nanophosphor has been characterized for its structural, morphological, and optical properties, by employing different analytical tools. This sensing platform is suitable for dsDNA probing by tracing the “turn on” fluorescence signal generated by CEY@SiO2-CH nanophosphor with the addition of dsDNA. The ratio of fluorescence intensity enhancement is proportional to the concentration of dsDNA in the range 0.1–90 nM, with the limit of detection at ⁓16.1 pM under optimal experimental conditions. The enhancement in fluorescence response of functionalized core-shell phosphor with dsDNA is due to the antenna effect. Additionally, response of probe has been studied for the real samples displaying percent recovery in between 101 and 105, maximum RSD% upto 5.23 (n = 3). This outcome can be applied to the selective sensing of dsDNA through optical response. These findings establish the CEY@SiO2-CH a simple, portable, and potential candidate as a sensor for rapid and analytical detection of dsDNA. © 2023 Elsevier B.V.
A flexible Eu:Y2O3-polyvinyl alcohol photoluminescent film for sensitive and rapid detection of arsenic ions
(Elsevier Inc., 2022) Arpita Dwivedi; Monika Srivastava; Rajnikant Upadhyay; Amit Srivastava; R.S. Yadav; S.K. Srivastava
The present article reports the synthesis and characterization of Eu:Y2O3 nanophosphor (EYN) and EYN dispersed polyvinyl alcohol (PVA) fluorescent film (EYF), with subsequent studies of sensing behavior for the detection of heavy metal ions particularly arsenic ions (As3+) in real water samples. Various characterization techniques have been employed to confirm the successful phase formation/stability of EYF. The maximum emission peak for EYF with excitation wavelength 394 nm has been obtained as 612 nm and hence picked for the demonstration of PL (Photoluminescence) response with arsenic ions solution in natural pH range (at ∼ 7 pH). Fluorescence intensities of EYF have been found to decrease quickly with As3+ ion contents due to the reduction in the population of Eu3+ ions in the 5D0 level and also due to formation of direct or indirect coordinate bonds with Eu3+. The PL intensity of the EYF nanoprobe has completely been quenched at 260 µg/L concentration of As3+ ions with the limit of detection 57.5 ng/L (=0.057 ppb) for 0–100 µg/L linear range. The selectivity of EYF probe is also investigated for various common cations and ions present in real water samples. Moreover, sensing probe has been examined with different river water samples and shows recovery percent in between 98 and 105 & maximum % RSD value as 5.76 with n = 5 tests. Furthermore, the EYF sensing probe shows a visible color change with the contaminated water under UV–Vis light which useful for the onsite detection of arsenic concentration. Hence, EYF endows a promising pathway for a flexible, portable, low-cost sensing device for the sensitive and selective detection of arsenic ions in real water samples. © 2021 Elsevier B.V.
Alkali metal ion codoped Eu3+ activated yttrium orthovanadate with tunable photoluminescence properties for LEDs and anti-counterfeiting applications
(Elsevier Ltd, 2025) Anuradha; Arpita Dwivedi; Satyam Upadhyay; Amit Kumar Srivastava; Monika Srivastava; Rajneesh Kumar; Sanjay Kumar Srivastava
The present experimental report articulates a comprehensive investigation on the synthesis, structural, and photoluminescence characteristics of M0.05,Eu0.05:Y0.90VO4 (M = Li+, Na+, K+) nanophosphors synthesised by auto-combustion approach, for optical display and anticounterfeiting technologies. Various characterization tools such as X-ray diffractometer (XRD), Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), Fourier transform infra-red (FTIR) Spectroscope, and Raman spectroscope have been employed to understand the morphology and crystal structure of M0.05,Eu0.05:Y0.90VO4 (M = Li+, Na+, K+) nanophosphor, which reveals the formation of a pure tetragonal structure and well crystalline phase. Moreover, the UV–Vis spectra, suggests that the as-synthesised material substantiated to possess an energy band gap of ∼3.6 eV conjecturing it as a wide-band material, and the refractive index (n) of the prepared samples has been deduced as ∼ 2.1. Among all alkali ions, Li+-codoped sample exhibits the most intense PL spectra. The enhancement in PL intensity has been observed due to the energy transfer of VO43−→Eu3+ and the codoping of lithium ions acts as a good charge compensator. For the optimized sample CIE coordinates has been found as (0.59, 0.39) and CCT value as 1712 K, which suggest it as a prospective candidate for the warm LEDs. The optimized sample has further been investigated for the visualization of Latent fingerprint on glass slide and as security ink. It displays efficient applicability as a well-defined ridge features up to level III. Henceforth, the as-synthesised Li0.05,Eu0.05:Y0.90VO4 nanophosphor may potentially be applied for multipurpose applications. © 2024 Elsevier Ltd and Techna Group S.r.l.
Biosynthesis of ZnO and TiO2 nanoparticles using Ipomoea carnea leaf extract and its effect on black carrot (Daucus carota L.) cv. Pusa Asita
(Elsevier Masson s.r.l., 2023) Deen Dayal Upadhyay; Ankit Kumar Goyal; Sutanu Maji; Arpita Dwivedi; Gajanan Pandey
Nano fertilizers (NFs) are now becoming an important tool for plant nutrient management having capabilities to improve soil fertility, crop productivity and quality of agricultural products. Since, they are needed in very small amount, thus, reduces cost of crop production. Among different essential or beneficial plant nutrients, Zn and Ti are important micro nutrients having number of beneficial effect on crop growth, yield, quality and post harvest life. Present experiment was carried out to prepare ZnO and TiO2 nanoparticles (NPs) through green technology by using aqueous extract of Ipomoea carnea (morning glory) leaves. In order to investigate size, morphology, composition, and stability of selected NPs, the detailed characterization was carried out using UV–visible spectroscopy, FTIR, HRTEM, EDX, BET, X-ray diffraction, XPS and particle size distribution studies. Subsequently, the effect of foliar spray of ZnO and TiO2 NPs was evaluated in respect of vegetative growth, yield and quality of black carrot (Daucus carota L.) cv. Pusa Asita in presence of 50% Recommended dose of fertilizer (RDF) to assess their effect on fertilizer use efficiency also. There were 8 treatments viz. Control (no fertilizer), recommended dose of fertilizer (RDF), TiO2 (5, 10 and 15 ppm along with 50% RDF), ZnO (50, 75 and 100 ppm along with 50% RDF)] with 3 replications following Randomised Block Design having 24 plots (1 m × 1 m). The observations were taken for vegetative growth, edible root yield and root quality parameters. Although, the growth, yield and quality parameters were found superior (root yield 43.84 g/plant) under conventional system of recommended dose of fertilizers (RDF) of NPK, however, TiO2 NPs also showed very promising result close to RDF as compared to ZnO NPs. Among them, 5 ppm TiO2 foliar application along with 50% NPK was found to be the best in terms of vegetative growth, root yield (38.73 g/plant) and quality of black carrot. It was also found that higher concentration of TiO2 and ZnO NPs had adverse effect on the plant performance. Therefore, it can be concluded that 5 ppm TiO2 NPs along with 50% RDF was good for black carrot production. © 2023 Elsevier Masson SAS
Enhance photoluminescence properties of Ca-Eu:Y2O3@SiO2 core–shell nanomaterial for the advanced forensic and LEDs applications
(Elsevier B.V., 2023) Arpita Dwivedi; Anuradha; Monika Srivastava; Amit Srivastava; Rajneesh Kumar; Sanjay Kumar Srivastava
The divalent (Ca2+)-doped Eu:Y2O3@SiO2 core–shell luminescent nanophosphors have been synthesised by a cost-effective combustion technique. Various characterizations were carried out to confirm the successful formation of the core–shell structure. The TEM micrograph reveals the thickness of the SiO2 coating over Ca-Eu:Y2O3 as ∼25 nm. The optimal value of silica coating over the phosphor has been obtained as 10 vol%(TEOS) of SiO2, with this value increasing fluorescence intensity by 34 %. Phosphor exhibits CIE coordinates as x = 0.425, y = 0.569 and a CCT value as ∼2115 K with color purity and the respective CRI of 80 % and 98 %, respectively, which make the core–shell nanophosphor suitable for warm LEDs, and other optoelectronic applications. Further, the core–shell nanophosphor has been investigated for the visualisation of latent finger prints and as security ink. The findings point towards the prospective future application of nanophosphor materials for anti-counterfeiting purposes and latent finger prints for forensic purposes. © 2023 Elsevier B.V.
Gold nanorods modified Eu: Y2O3 dispersed PVA film as a highly sensitive plasmon-enhanced luminescence probe for excellent and fast non-enzymatic detection of H2O2 and glucose
(Elsevier GmbH, 2021) Dhananjay Kumar; Arpita Dwivedi; Monika Srivastava; Anchal Srivastava; Amit Srivastava; S.K. Srivastava
This article addresses a high sensitivity, non-invasive, and use-throw in nature type biocompatible Eu: Y2O3 dispersed PVA film with gold nanorod (AEYCP film) fluorescent sensing probe for non-enzymatic detection of hydrogen peroxide (H2O2) and glucose (C6H12O6). The fluorescence spectra of the as-synthesized AEYCP fluorescent film consist of some sharp emission (most intense peak at ∼611 nm, owing to the 5D0-7F2 transition) which corresponds to electrical and magnetic dipole transitions. In the presence of H2O2 and glucose, the fluorescence intensity of the AEYCP film gets quenched due to the reduction of electron-hole pair, at the Eu center. The AEYCP film shows excellent fluorescence quenching in the presence of H2O2 at ∼500 nM (with a low detection limit of 1.80 × 10−9 M) and glucose (with a low detection limit 1.60 × 10-6 M). Herein, we envision that our result provides an insight for the synthesis of rare earth metal-doped oxide flexible,non-enzyme mimicking fluorescent probe for different biomedical applications. © 2020 Elsevier GmbH
Ho3+activated Ca0.5Y1.90-xO3 green-emitting nanophosphors for solid state lightening: Synthesis, characterization and photoluminescence properties
(Elsevier B.V., 2022) Arpita Dwivedi; Monika Srivastava; S.K. Srivastava
This paper presents a series of Ho3+activated Ca0.5Y1.90-xO3 green-emitting nanophosphors using the facile solution combustion method. X-ray diffraction (XRD) and Transmission electron microscope (TEM) confirm the phase purity, structural morphology with cubic phase, and irregular shape particle with the average particle size of 21 nm. Diffuse reflectance spectra of the recorded and band gap estimated by Tauc's equation which is 5.78 eV, 4.90 eV for direct and indirect band gaps for 2 mol% of Ho3+, respectively. Under the excitation of 448 nm wavelength (5I8 → 3G6), the doped samples display characteristic emission of Ho3+ ions correspond to 5S2 → 5I8 (at 551 nm) transition, which fall in a strong green region. The optimal concentration for Ho3+ doping is found as 2 mol%, after this quenching of photoluminescence (PL) intensity occurred and this is accredited due to dipole-dipole interaction. The proposed nanophosphor also displays the good thermal stability with activation energy of 0.23 eV. The nanophosphor confirms the excellent color purity (98%), CRI (98.36%), and CCT value (5724 K). With this, nanophosphor also exhibits good quantum efficiency of 81.1% under the 448 nm excitation wavelength. These results direct that the Ho3+activated Ca0.5Y1.90-xO3 nanophosphor may have potential applicability for green-emitting LEDs, display device and optoelectronic applications. © 2021 Elsevier B.V.
Impact of Eu3 +/Y3+ doping on the structural and optical properties of SrTiO3 perovskite phosphor and multi-functional applications
(Elsevier Ltd, 2025) Satyam Upadhyay; Arpita Dwivedi; Prateek Kumar Yadav; Monika Srivastava; Amit Kumar Srivastava; Chandan Upadhyay; Sanjay Kumar Srivastava
A latent fingerprint (LFP) examination is essential for identifying fingerprints at crime sites, and personal data for legal operations requires economical, eco-friendly, and sensitive new materials. Here, a new composition of intense red-emitting Eu3+ and Y3+ co-doped SrTiO3 perovskites nanophosphor synthesized using a modified sol-gel-assisted combustion technique has been reported. To explore the structural and optical features of the nanophosphors the samples are characterized by various techniques. The powder XRD pattern reveals that the approximate crystallite size is 30 nm, which is consistent with TEM. It is found that with the mid- and near-ultraviolet light excitation, Eu3+ and Y3+ co-doped SrTiO3 nanophosphor displays a strong red emission at 618 nm for optimal concentrations (3 mol% Eu). The CIE (0.656, 0.344), color purity 95 %, CRI 98 %, and CCT values 2435 K, which is less than 5000 K reveals that the Eu3+ and Y3+ co-doped SrTiO3 phosphor was highly useful for the fabrication of warm LED and display device applications. Further, the optimized phosphor was tested (under UV light of 254 nm) for the visualization of LFP and security ink on various material surfaces. The results demonstrated that it provides an effective method for visualizing ridge patterns, offering a promising approach for applications in these areas. Based on the findings, Eu3+ and Y3+ co-doped SrTiO3 show potential for various optoelectronic applications, including WLEDs, LFP detection, security inks, and LEDs. © 2025 Elsevier B.V.
Investigations of coal beneficiation by using choline chloride and urea-based deep eutectic solvent
(Taylor and Francis Ltd., 2023) Ankur Dwivedi; Arpita Dwivedi; Amrendra Kumar
The present study reports on the interaction, influence, and dissolution properties of coal samples (CS) by a green solvent, deep eutectic solvent (DES), prepared from choline chloride and urea. The bituminous coal has been collected from the Singrauli coalfield in India. DES was synthesized using urea as a hydrogen bond acceptor (HA) and choline chloride as a hydrogen bond donor (HD) in an equimolar amount. The synthesized DES has been used in the study for swelling behavior, proximate and ultimate analysis, and FTIR to understand the beneficiation of coal after DES treatment. The swelling index of DES-treated coal ranges from 1.12 to 1.43 when compared to raw CS. FTIR confirms the presence of different oxygen-containing phenolic, aromatic, and aliphatic hydrocarbon containing functional groups present in coal samples. Quantitative analysis of FTIR peaks was carried out through the Gaussian function peak processing method. Fourier transform infrared (FTIR) analysis of the raw coal and treated sample confirms the reduction of oxygen-carrying and phenolic vibrational groups by up to 86%. The ultimate and proximate analysis of raw coal and DES-treated CS shows the decrease in ash content (up to 26%) of DES-treated coal samples and confirms the FTIR results. Calorific value in the form of fixed carbon content was also increased by up to 4.7% after DES treatment. Hence, DES treatment efficiently benefits coal properties and makes them more useful for the industrial environment. © 2022 Taylor & Francis Group, LLC.
Qualitative surface characterization of Indian Permian coal using XPS and FTIR
(Taylor and Francis Ltd., 2023) Ankur Dwivedi; Arpita Dwivedi; Amrendra Kumar
This paper reports on the surface properties associated with high-ash Indian Permian coal, which primarily depend on its geochemical compositions. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) techniques have been used to assess surface properties. The results confirm the presence of different elements, mineral phases, and organic functional groups in coal. The XPS survey confirms the presence of different elements on the surface of the coal. Some of them are C 1s (286.0 eV), O 1s (534.5 eV), N 1s (399.9 eV), S 2p (158.2 eV), such as SiO2 and Al2O3, which correspond to Si 2p (102.7 eV) and Al 2p (75.6 eV) with other clay minerals. XPS spectra of C 1s confirm the presence of aliphatic and aromatic carbon, which are hydrophobic compared to hydrophilic groups such as alcoholic, carboxylic, and phenolic. FTIR also validates the existence of hydrophobic functional groups as being higher than hydrophilic groups. Proximate and ultimate analysis results also confirm the presence of less moisture and a higher carbon percentage in the coal samples. Hence, the inherent hydrophobicity of the coal surface is excellent, and the surface hydrophobicity of coal can also be characterized using XPS and FTIR techniques. This information about the coal properties will be very beneficial for coal beneficiation and utilization. © 2022 Taylor & Francis Group, LLC.
Recent advancements of smartphone-based sensing technology for diagnosis, food safety analysis, and environmental monitoring
(Elsevier B.V., 2024) Satyam Upadhyay; Anil Kumar; Monika Srivastava; Amit Srivastava; Arpita Dwivedi; Rajesh Kumar Singh; S.K. Srivastava
The emergence of computationally powerful smartphones, relatively affordable high-resolution camera, drones, and robotic sensors have ushered in a new age of advanced sensible monitoring tools. The present review article investigates the burgeoning smartphone-based sensing paradigms, including surface plasmon resonance (SPR) biosensors, electrochemical biosensors, colorimetric biosensors, and other innovations for modern healthcare. Despite the significant advancements, there are still scarcity of commercially available smart biosensors and hence need to accelerate the rates of technology transfer, application, and user acceptability. The application/necessity of smartphone-based biosensors for Point of Care (POC) testing, such as prognosis, self-diagnosis, monitoring, and treatment selection, have brought remarkable innovations which eventually eliminate sample transportation, sample processing time, and result in rapid findings. Additionally, it articulates recent advances in various smartphone-based multiplexed bio sensors as affordable and portable sensing platforms for point-of-care devices, together with statistics for point-of-care health monitoring and their prospective commercial viability. © 2024 Elsevier B.V.
Synthesis and enhanced photoluminescence properties of red emitting divalent ion (Ca2+) doped Eu:Y2O3 nanophosphors for optoelectronic applications
(Editorial Office of Chinese Rare Earths, 2022) Arpita Dwivedi; Monika Srivastava; Ankur Dwivedi; Amit Srivastava; Anurag Mishra; S.K. Srivastava
This work presents the synthesis of Y2O3:Eu3+,xCa2+ (x = 0 mol%, 1 mol%, 3 mol%, 5 mol%, 7 mol%, 9 mol%, 11 mol%) nanophosphors with enhanced photoluminescence properties through a facile solution combustion method for optoelectronic, display, and lighting applications. The X-ray diffraction (XRD) patterns of the proposed nanophosphor reveal its structural properties and crystalline nature. The transmission electron microscope (TEM) results confirm the change in the shape of the particle and aggregation of particles after co-doping with Ca2+. Fourier transform infrared spectroscopy (FTIR) and Raman vibrations also confirm the presence of Y–O vibration and subsequently explain the crystalline nature, structural properties, and purity of the samples. All the synthesized nanophosphors samples emit intense red emission at 613 nm (5D0→7F2) under excitation with 235, 394 and 466 nm wavelengths of Eu3+ ions. The photoluminescence (PL) emission spectra excited with 235 nm illustrate the highest emission peak with two other emission peaks excited with 466 and 394 nm that is 1.4 times higher than 466 nm and 1.9 times enhanced by 394 nm wavelength, respectively. The emission intensity of Y2O3:Eu3+,xCa2+ (5 mol%) is increased 8-fold as compared to Eu:Y2O3. Doping with Ca2+ ions enhances the emission intensity of Eu:Y2O3 nanophosphors due to an increase in energy transfer in Ca2+→Eu3+ through asymmetry in the crystal field and by introduction of radiative defect centers through oxygen vacancies in the yttria matrix. It is also observed that the optical band gap and the lifetime of the 5D0 level of Eu3+ ions in Y2O3:Eu3+,xCa2+ nanophosphor sample gets changed with a doping concentration of Ca2+ ions. Nanophosphor also reveals high thermal stability and quantum yield as estimating activation energy of 0.25 eV and 81%, respectively. CIE, CCT, and color purity values (>98%) show an improved red-emitting nanophosphor in the warm region of light, which makes this material superior with a specific potential application for UV-based white LEDs with security ink, display devices, and various other optoelectronics devices. © 2021 Chinese Society of Rare Earths
Synthesis of high luminescent Eu3+ doped nanoparticle and its application as highly sensitive and selective detection of Fe3+ in real water and human blood serum
(Elsevier B.V., 2021) Arpita Dwivedi; Monika Srivastava; Amit Srivastava; S.K. Srivastava
The present work reports a highly efficient Ca doped Eu: Y2O3 i.e Ca0.05Eu0.01Y1.94O3 (CEY.) nanophosphor material synthesized through a facile combustion method, as a simple and selective turn-off fluorescence probe for the quantitative analysis of iron ions (Fe3+). The proposed sensor allows the quantification of iron in the range of 10 µM–90 µM with a limit of detection (LOD) ∼ 63.2 nM under the natural pH range. Moreover, CEY nanophosphor shows an excellent fluorescence phenomenon with a gradual increase in the Fe3+ ion concentration. It has been observed that the corresponding PL intensity gets completely quenched with 500 µM Fe3+ ion concentration. Furthermore, the applicability of the sensor as an efficient probe has been investigated with real water samples, iron tablets, and human blood serum (HBS). The selectivity of the probe has also been analyzed with various metal ions and biomolecules. Thus, in turn, the as-obtained sensing probe illustrates an excellent accuracy, sensitivity, and selectivity, and offers potential application in clinical diagnosis, biological and real water sample studies, with the detection of Fe3+ ion. Furthermore, it does not require any acidic medium for a level-free, and non-enzymic detection of a real sample with almost not affecting the sample quality and henceforth provides more reliable results. © 2021 Elsevier B.V.
Tunable photoluminescence and energy transfer of Eu3+,Ho3+-doped Ca0.05Y1.93-xO2 nanophosphors for warm white LEDs applications
(Nature Research, 2022) Arpita Dwivedi; Monika Srivastava; Amit Srivastava; Chandan Upadhyay; Sanjay Kumar Srivastava
A series of Eu3+ ions doped Ca0.05Y1.93-xO3:0.02Ho3+ (CYO:Ho3+,xEu3+) nanophosphors having multicolour tuneability have been synthesised by following a simplistic solution combustion approach. The synthesised samples have been characterised by employing X-ray diffraction (XRD), Transmission electron microscope (TEM), and Fourier transforms infrared spectroscopy (FTIR). The optical properties have been engrossed by UV–visible and photoluminescent excitation and emission spectra, and decay lifetimes measurements. The characteristic emission, which occurs due to the f-f transition of Ho3+ and Eu3+ has been observed in emission spectra with excitation of 448 nm. By adjusting the doping ratio of Ho3+/Eu3+, the as-synthesized nanophosphor accomplishes multicolour tunability from green-yellow to red. Emission spectra and decay lifetime curve recommend dipole–dipole interaction causes energy transfer from Ho3+ → Eu3+. The energy transfer process from Ho3+ to Eu3+ has been confirmed through electric dipole–dipole interaction with critical distance 15.146 Å. Moreover, temperature dependent emission spectra show the high thermal stability with an activation energy ⁓ 0.21 eV, with the quantum efficiency of 83.6%. CIE coordinate illustrates that the singly doped Ho3+ and Eu3+ lie in the green and red region, respectively, while the as-synthesized CYO:Ho3+,xEu3+shows tunability from green to red with low CCT and high colour purity values. Hence, the CYO:Ho3+,xEu3+nanophosphor may be a near-UV excited multicolour colour-tunable pertinent candidate with potential prospects for multicolour- display and near-ultraviolet lighting applications. © 2022, The Author(s).