Browsing by Author "Prince Kumar"

Now showing 1 - 10 of 10

Engineered ultra-luminous La/YPO4:Eu3+ nanophosphors for advanced security ink and latent fingerprint (LFPs) detection
(Elsevier Ltd, 2024) Prince Kumar; P.K. Vishwakarma; S.B. Rai; A. Bahadur
Designing versatile NPs for multifarious applications is crucial for achieving an array of criterion in realm, including improving efficiency, inexpensiveness, flexibility, least power consumption, etc. Facile hydrothermal treatment of La/YPO4:Eu3+ NPs yields composite phase growth signifying even-sized NPs with the requisite elemental composition. Relative CTB predominates in LaPO4:Eu3+; while luminescence of YPO4:Eu3+ is notably higher when stimulated by atomic lines. Nevertheless, La/YPO4:Eu3+ NPs exhibit adequate luminescence under both CTB and 394 nm (7F0→5L6) excitations, evincing intrinsic QY (63.91 %) with relatively large lifetime (∼6 ms) of 5D0 states, substantiated by J-O analysis. Designed NPs is readily cling to friction ridge skin residues demonstrating the efficient LFPs development through the ‘powder dusting approach’ on various substrate. NPs conjugated PVC gold medium and aqueous PVA were effectively used for security encryptions using the screen-printing technique. Reddish-orange emission with different excitation probabilities resulting in high QY emphasizes them in a class of futuristic versatile materials with potential applications in security ink, LFP development, LEDs, and display devices. © 2024 Elsevier B.V.
Enhancing milk quality assessment with watermelon (Citrullus lanatus) urease immobilized on VS2-chitosan nanocomposite beads using response surface methodology
(Elsevier Ltd, 2024) Prince Kumar; Divya; Amit Kumar Patel; Anchal Srivastava; Arvind M. Kayastha
An eco-friendly hydrothermal method synthesized VS2 nanosheets. Several spectroscopic and microscopic approaches (TEM) were used to characterize the produced VS2 nanosheet microstructure. VS2, Chitosan, and nanocomposite were used to immobilize watermelon (Citrullus lanatus) urease. Optimization using the Response Surface Methodology and the Box-Behnken design yielded immobilization efficiencies of 65.23 %, 72.52 %, and 87.68 % for chitosan, VS2, and nanocomposite, respectively. The analysis of variance confirmed the mathematical model's validity, enabling additional research. AFM, SEM, FTIR, Fluorescence microscopy, and Cary Eclipse Fluorescence Spectrometer showed urease conjugation to the matrix. During and after immobilization, FTIR spectra showed a dynamic connectivity of chemical processes and bonding. The nanocomposite outperformed VS2 and chitosan in pH and temperature. Chitosan and VS2-immobilized urease were more thermally stable than soluble urease, but the nanocomposite-urease system was even more resilient. The nanocomposite retained 60 % of its residual activity after three months of storage. It retains 91.8 % of its initial activity after 12 reuse cycles. Nanocomposite-immobilized urease measured milk urea at 23.62 mg/dl. This result was compared favorably to the gold standard p-dimethylaminobenzaldehyde spectrophotometric result of 20 mg/dl. The linear range is 5 to 70 mg/dl, with a LOD of 1.07 (±0.05) mg/dl and SD of less than 5 %. The nanocomposite's ksel coefficient for interferents was exceptionally low (ksel < 0.07), indicating urea detection sensitivity. Watermelon urease is suitable for dairy sector applications due to its availability, immobilization on nanocomposite, and reuse. © 2024 Elsevier Ltd
Exploring the catalytic potential of watermelon urease: Purification, biochemical characterization, and heavy metal precipitation
(Elsevier B.V., 2024) Prince Kumar; Divya; Arvind M. Kayastha
Bioactive urease from watermelon (Citrullus lanatus) seeds was purified using acetone fractionation, anion-exchange, and size-exclusion chromatography, achieving a 121-fold increase and specific activity of 3216 U/mg. The enzyme appeared as a single band on native and SDS-PAGE, with a molecular mass of 480 ± 10 kDa and subunit mass of 80 ± 10 kDa, indicating six identical subunits. Atomic absorption spectroscopy revealed 1.46 nickel ions per subunit. Watermelon urease exhibited serological similarities with jack bean and pigeon pea ureases, an optimal pH of 7.3, an activation energy of 3 kcal/mol, Vmax of 3571 μmol/min/mg, and Km of 0.16 mM. The enzyme displayed biphasic thermal and pH inactivation kinetics, a strong preference for urea, and a half-life of 70 days with 1 mM DTT. This study highlights watermelon urease's role in bioremediation by facilitating the precipitation of heavy metals as stable carbonates, promoting environmental sustainability. © 2024 Elsevier B.V.
Immobilized pigeon pea urease on chitosan-PEG biocomposite for concurrent urea sensing in milk and blood samples
(Elsevier Ltd, 2025) Prince Kumar; Aditya Ghosal; Arvind Mohan Kayastha
The ubiquitous hydrolytic enzyme urease converts urea into ammonia and carbon dioxide, making it an essential indicator for dairy product quality and kidney health. We developed a biocomposite sensor to meet this diagnostic necessity. This innovation strategically incorporates pigeon pea seed urease into chitosan-PEG. We verified our predicted model with a 91.30 % immobilization efficiency via our thorough process. The immobilized urease showed strong catalytic activity, with a Vmax of 3194 μmol/min/mg and a Km of 0.373 mM. Optimal activity was observed at 90 °C and pH 8.0. Additionally, it exhibited exceptional operational stability, maintaining 56 % activity over 200 days at 4 °C and 60 % reusability over 11 cycles. The sensor showed a wide linear detection range (5–400 mg/dL) with high sensitivity (LOD 3.10 (±0.155) mg/dL, LOQ 10.36 (±0.510) mg/dL). Its high selectivity (Ksel < 0.08) ensures precise urea detection in complex milk and blood matrices. This stable and reproducible biocomposite is a breakthrough in dairy and healthcare analytical tools. © 2025 Elsevier Ltd
In Silico Structural and Functional Insight into the Binding Interactions of the Modeled Structure of Watermelon Urease with Urea
(American Chemical Society, 2024) Prince Kumar; Arpan Kayastha; Vinay Kumar Singh; Arvind M. Kayastha
Urease (EC 3.5.1.5) is an amidohydrolase. This nickel-dependent metalloenzyme converts urea into NH3 and CO2. Despite their vital role in plants, the structure and function of watermelon (Citrullus lanatus) urease are unknown. We used third- and fourth-generation gene prediction algorithms to annotate the C. lanatus urease sequence in this investigation. The solved urease structure from Canavalia ensiformis (PDB ID: 4GY7) was utilized as a template model to identify the target 3-D model structure of the unknown C. lanatus urease for the first time. Cluretox, the C. lanatus urease intrinsic disordered area identical to Jaburetox, was also found. The C. lanatus urease structure was docked with urea to study atom interaction, amino acid interactions, and binding analyses in the urease-urea complex at 3.5 Å. This study found that amino acids His517, Gly548, Asp631, Ala634, Thr569, His543, Met635, His407, His490, and Ala438 of C. lanatus urease bind urea. To study the molecular basis and mode of action of C. lanatus urease, molecular dynamics simulation was performed and RMSD, RMSF, Rg, SAS, and H-bond analyses were done. The calculated binding free energy (ΔG) for the urea-urease complex at 100 ns using the MM/PBSA method is −7.61 kJ/mol. Understanding its catalytic principles helps scientists construct more efficient enzymes, tailor fertilization to boost agricultural output, and create sustainable waste management solutions. © 2023 The Authors. Published by American Chemical Society
Nanotechnology Developments in Active Food Packaging
(Springer Science+Business Media, 2025) Avinash Kumar; Prince Kumar; Arvind Mohan Kayastha
Nanofillers are fillers with particle diameters between 1 and 100 nm. Examples of such fillers are carbon blacks, synthetic silicas, and precipitated calcium carbonate. Food packaging often uses nanofillers to improve factors including heat and moisture resistance, gas leakage, and packing properties. The most popular nanofillers, such as nanorod, nanofibril, and nanotube varieties, are used in food packaging. The nanosized fillers can be either organic or inorganic, such as carbon nanotubes, graphene nanosheets, natural antimicrobials like nisin, natural biopolymers like chitosan, clay (such as montmorillonite and kaolinite), metals like silver, and metal oxides like TiO[[inf]]2[[/inf]]. Nanofillers offer antimicrobial properties through the creation of cutting-edge packaging technologies to sense biochemical or microbiological changes in food and detect the diseases and their root causes to be utilized as a product monitoring tool for food safety and to prevent food fraud. Laboratory studies, commercial applications, and development trends point to the existence of numerous categories of uses for nanofillers in the food packaging sector, including enhanced packaging, intelligent packaging, and active packaging. © 2025 Springer Nature Singapore Pte Ltd.
Study of array plasma antenna parameters
(American Institute of Physics Inc., 2018) Rajneesh Kumar; Prince Kumar
This paper is aimed to investigate the array plasma antenna parameters to help the optimization of an array plasma antenna. Single plasma antenna is transformed into array plasma antenna by changing the operating parameters. The re-configurability arises in the form of striations, due to transverse bifurcation of plasma column by changing the operating parameters. Each striation can be treated as an antenna element and system performs like an array plasma antenna. In order to achieve the goal of this paper, three different configurations of array plasma antenna (namely Array 1, Array 2 and Array 3) are simulated. The observations are made on variation in antenna parameters like resonance frequency, radiation pattern, directivity and gain with variation in length and number of antenna elements for each array plasma antenna. Moreover experiments are also performed and results are compared with simulation. Further array plasma antenna parameters are also compared with monopole plasma antenna parameters. The study of present paper invoke the array plasma antenna can be applied for steering and controlling the strength of Wi-Fi signals as per requirement. © 2018 Author(s).
UV-guided enhanced green luminescence in Y2O3/ZnO:Tb3+ composite via induced defect state and applied for latent fingerprinting application
(Elsevier B.V., 2025) Prince Kumar; Pradeep Kumar Vishwakarma; Shyam Bahadur Rai; Amresh Bahadur
The Y2O3/ZnO:Tb3+ composite was synthesized through the solid-state reaction method. XRD analysis confirms the phase formation corresponding to JCPDS #36–1451 (ZnO) and #43–1036 (α-Y2O3), revealing nano order crystallinity, negative strain, and 76:24 % occupancy of Y2O3/ZnO. The submicron-sized particles subsequently increased upon Tb3+ doping as shown in FE-SEM images. Elemental mapping and XPS analyses confirm the composition, oxidation state, and presence of oxygen vacancies. The DRS spectra show that the band gaps of Y2O3 & ZnO are 5.28 eV and 3.27 eV, respectively. An intense green emission at 520 nm due to ZnO defect states and at 543 nm due to 5D4→7F5 transition was observed under λEx = 378 and 305 nm, respectively. Interestingly, ZnO emits a broad band from 385 to 700 nm region through 378 or 340 nm excitations. The Tb3+ ion-induced tunability due to modification in defects, is well supported by decay analysis. The intense green and whitish green emission of Tb3+ ion and composite has been successfully applied in latent fingerprint detection. © 2025 Elsevier B.V.
Watermelon (Citrullus lanatus) urease immobilized on chitosan-unzipped multi-walled carbon nanotubes (UZMWCNTs) nanobiocomposite for enhanced blood urea sensing
(Elsevier B.V., 2025) Prince Kumar; Ahsan Ali; Anchal Srivastava; Arvind Mohan Kayastha
Urease, a hydrolytic enzyme, facilitates the conversion of urea into ammonia and carbon dioxide and serves as a critical biomarker for assessing renal function. Developing a sensor to monitor urea is essential, as elevated urea levels in the blood often indicate renal impairments. In contrast, low levels may reflect inadequate protein intake or diminished kidney performance. To address this need, a novel nanobiocomposite was synthesized by incorporating purified urease from watermelon into chitosan-modified chemically unzipped multi-walled carbon nanotubes (UZMWCNTs). High immobilization efficiency (92.5 %) validated predictive modeling. Immobilized urease exhibited a Vmax of 3225.8 µmol/min/mg and Km of 0.24 mM. At 277 K, 53 % activity was retained after 200 days. Operational stability showed 90 % activity after 13 cycles. The sensor exhibited a broad linear detection range from 10 mg/dL to 400 mg/dL. It demonstrated exceptional sensitivity, with a limit of detection (LOD) of 3.17 ± 0.158 mg/dL and a limit of quantification (LOQ) of 10.58 ± 0.52 mg/dL. Its high selectivity, highlighted by a selectivity coefficient below 0.1 (ksel < 0.1), ensured precise urea detection even within complex biological samples. Validation using artificial blood serum revealed recovery rates of 86.4–96.9 % (RSD < 5 %), underscoring the sensor's reliability and accuracy. The nanobiocomposite also showcased excellent stability and reproducibility, making it a promising tool for clinical applications. This sensor offers a robust solution for precise and efficient urea quantification, paving the way for enhanced diagnostics of renal health. © 2025 Elsevier B.V.
Watermelon Derived Urease Immobilized Gold Nanoparticles-Graphene Oxide Transducer for Direct Detection of Urea in Milk Samples
(American Chemical Society, 2024) Prince Kumar; Daphika S. Dkhar; Pranjal Chandra; Arvind M. Kayastha
Urea contamination in milk poses significant health risks, including kidney failure, urinary tract obstruction, fluid loss, shock, and gastrointestinal bleeding. This highlights the need for sensitive, rapid, and reliable methods to detect traces amount of urea in milk. In this study, we designed an electrochemical transducer for urea detection by utilizing purified watermelon urease (Urs), gold nanoparticles (AuNPs), and graphene oxide (GO). The nanomaterials and biosensor probe were characterized using UV-vis spectroscopy, XPS, TEM, XRD, FTIR, AFM, CV, EIS, and DPV. The engineered probe (GCE/AuNPs/GO/Urs) demonstrated a broad linear detection range of 5 to 90 mg/dL and a low limit of detection (LOD) of 0.037 (±0.012) mg/dL (RSD < 3.7%). The biosensor was tested for potential interferents that may be present in adulterated milk and an exceptionally low coefficient of selectivity (ksel <0.1) was obtained. Evaluation of milk samples from a local dairy farm showed good recovery rates from 93.13% to. 98.79% (RSD < 4.28%, n = 3), indicating reliable detection capabilities. Stability tests confirmed the sensor’s reproducibility and consistent performance. Additionally, a comparison study of the system was carried out using the purified watermelon urease and the commercially available urease. Herein, the results obtained using the sensor probe was finally validated with the gold standard method. © 2024 American Chemical Society.