A biogenic hydrogel to recover Au(III) from electronic waste.

In the course of this investigation, we undertook the contemplation of a green chemistry paradigm with the express intent of procuring valuable metal, namely gold, from electronic waste (e-waste). In pursuit of this overarching objective, we conceived a procedural framework consisting of two pivotal stages. As an initial stage, we introduced a physical separation procedure relying on the utilization of the Eddy current separator, prior to embarking on the process of leaching from e-waste. Subsequent to the partitioning of metals from the non-metal constituents of waste printed circuit boards (PCB), we initiated an investigation into the hydrogel derived from basil seeds (Ocimum basilicum L.), utilizing it as a biogenic sorbent medium. The thorough characterization of hydrogel extracted from basil seeds involved the application of an array of analytical techniques, encompassing FTIR, XRD, SEM, and BET. The batch sorption experiments show more than 90% uptake in the pH range of 2-5. The sorption capacity of the hydrogel material was evaluated as 188.44 mg g-1 from the Langmuir Isotherm model. The potential interference stemming from a spectrum of other ions, encompassing Al, Cu, Ni, Zn, Co, Cr, Fe, Mn, and Pb was systematically examined. Notably, the sole instance of interference in the context of adsorption of gold ions was observed to be associated with the presence of lead. The application of the hydrogel demonstrated a commendable efficiency in the recovery of Au(III) from the leached solution derived from the waste PCB.

Development of magnetic La doped Al2O3 core-shell nanoparticle loaded hydrogel for selective recovery of fluoride from aquatic medium.

The selective removal of pollutants from water bodies is regarded as a conciliation between the rapid expansion of industrial activities and need of clean water for sustainability. Fluoride is one such geogenic pollutant, and various materials have already been reported. Developing an efficient field employable material is however a challenge. Herein, we report the synthesis and competencies of strategically designed magnetic La-doped Al2O3 core-shell nanoparticle loaded polymeric nanohybrid as a benchmark fluoride sorbent. A facile synthesis strategy involved fabrication of Fe3O4 magnetic core followed by growth of La doped Al2O3 shell using sol-gel method. Doping of La2O3 into Al2O3 structure was optimised (6%), resulting in Fe3O4-Al0.94 La0.06O1.5 core-shell particles which provided exceptional fluoride affinity. The obtained magnetic Fe3O4-Al0.94La0.06O1.5 core-shell nanoparticles were then loaded (22%) into alginate to form cross-linked hydrogel beads (Fe3O4-Al0.94 La0.06 O1.5-Ca-ALG). These prepared hydrogel beads were characterised and utilized for selective recovery of fluoride under different ambient conditions. Driving forces for enhanced fluoride uptake by La doped Al2O3 were investigated and explained with the help of both experimental observation and theoretical simulation. Density functional theory calculations indicated significant expansion in the cell volume of Al2O3 due to La doping which favoured the fluoride sorption. The calculated defect formation energy for the incorporation of F into Al2O3 was found to decrease in the presence of La. XPS analysis suggested direct interaction of fluoride with Al, forming Al-F bond and breaking Al-O bond. Different vital parameters for uptake were optimised. Also, kinetics, isotherm and diffusion models were evaluated. Developed hydrogel beads attained record sorption capacity of 132.3 mgg-1 for fluoride. Overall, excellent stability, no leaching of constituents, effectiveness for selective fluoride recovery from groundwater, brand it a perfect epitome of sustainable water treatment application.

Synthesis of multicolor silver nanostructures for colorimetric sensing of metal ions (Cr3+, Hg2+ and K+) in industrial water and urine samples with different spectral characteristics.

In this work, we have synthesized four different color (yellow, orange, green, and blue (multicolor)) silver nanostructures (AgNSs) by chemical reduction method where silver nitrate, sodium borohydride and hydrogen peroxide were used as reagents. The as-synthesized multicolor AgNSs were successfully functionalized with bovine serum albumin (BSA) and applied as a colorimetric sensor for the assaying of metal cations (Cr3+, Hg2+, and K+). The addition of metal ions (Cr3+, Hg2+, and K+) into BSA functionalized AgNSs (BSA-AgNSs) causes the aggregation of BSA-AgNSs, and are accompanied by visual color changes with red or blue shift in the surface plasmon resonance (SPR) band of BSA-AgNSs. The BSA-AgNSs show different SPR characteristic for each metal ions (Cr3+, Hg2+, and K+) with exhibiting different spectral shift and color change. The yellow color BSA-AgNSs (Y-BSA-AgNSs) act as a probe for sensing Cr3+, orange color BSA-AgNSs (O-BSA-AgNSs) act as probe for Hg2+ ion assay, green color BSA-AgNSs (G-BSA-AgNSs) act as a probe for the assaying of both K+ and Hg2+, and blue color BSA-AgNSs (B-BSA-AgNSs) act as a sensor for colorimetric detection of K+ ion. The detection limits were found to be 0.26 µM for Cr3+ (Y-BSA-AgNSs), 0.14 µM for Hg2+ (O-BSA-AgNSs), 0.05 µM for K+ (G-BSA-AgNSs), 0.17 µM for Hg2+ (G-BSA-AgNSs), and 0.08 µM for K+ (B-BSA-AgNSs), respectively. Furthermore, multicolor BSA-AgNSs were also applied for assaying of Cr3+, and Hg2+ in industrial water samples and K+ in urine sample.

Perspectives of different colour-emissive nanomaterials in fluorescent ink, LEDs, cell imaging, and sensing of various analytes.

In the past 2 decades, multicolour light-emissive nanomaterials have gained significant interest in chemical and biological sciences because of their unique optical properties. These materials have drawn much attention due to their unique characteristics towards various application fields. The development of novel nanomaterials has become the pinpoint for different application areas. In this review, the recent progress in the area of multicolour-emissive nanomaterials is summarized. The different emissions (white, orange, green, red, blue, and multicolour) of nanostructure materials (metal nanoclusters, quantum dots, carbon dots, and rare earth-based nanomaterials) are briefly discussed. The potential applications of different colour-emissive nanomaterials in the development of fluorescent inks, light-emitting diodes, cell imaging, and sensing devices are briefly summarized. Finally, the future perspectives of multicolour-emissive nanomaterials are discussed.

Thiol functionalised silica microsphere loaded polymeric hydrogel: Development of a novel hybrid sorbent for removal of lead and cadmium.

Current study presents a facile synthesis method for thiol functionalised silica microsphere loaded polymeric hydrogel. Silica microspheres were synthesised as core shell particles by sol-gel method followed by hydrolysis and condensation reaction to form the silica core. The silica was functionalised with thiol and the functionalised silica microsphere was subsequently impregnated into polymeric alginate matrix to form thiol functionalised silica microspheres loaded alginate hydrogel beads (SH-SiO2MS-Ca-Alg). The developed components and final products were characterised by BET, FTIR, DLS, SEM-EDS. The developed SH-SiO2MS-Ca-Alg hydrogel beads were used for efficient removal of Pb and Cd [72-97 % for Pb; 60-85 % for Cd at concentration range of 0.1-100 µg mL-1 and optimum pH 5-7] from aquatic medium. The sorption capacities evaluated for Pb and Cd from Langmuir isotherm were 127.99 and 70.68 mgg-1 respectively. Uptake kinetics, isotherm, thermodynamics, intraparticle diffusion studies were carried out for both Pb (II) and Cd (II). Mechanism of Pb (II) and Cd (II) removal by SH-SiO2MS-Ca-Alg hydrogel hybrid beads was proposed with the help of zeta potentials of SH-SiO2MS at different pH along with fraction diagram of Pb and Cd.

An overview of molecular biology and nanotechnology based analytical methods for the detection of SARS-CoV-2: promising biotools for the rapid diagnosis of COVID-19.

Currently, the 2019 novel coronavirus (2019-nCoV) is drastically affecting 214 countries, causing severe pneumonia in patients, which has resulted in lockdown being implemented in several countries to stop its local transmission. Considering this, the rapid screening and accurate detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; 2019-nCoV) play an essential role in the diagnosis of COVID-19, which can minimize local transmission and prevent an epidemic. Due to this public health emergency, the development of ultra-fast reliable diagnostic kits is essential for the diagnosis of COVID-19. Recently, molecular biology and nanotechnology based analytical methods have proven to be promising diagnostic tools for the rapid screening of 2019-nCoV with high accuracy and precision. The main aim of this review is to provide a retrospective overview on the molecular biology tools (reverse transcription polymerase chain reaction (RT-PCR) and reverse transcription loop-mediated isothermal amplification (RT-LAMP)) and nanotechnology based analytical tools (enzyme-linked immunosorbent assay (ELISA), RT-PCR, and lateral flow assay) for the rapid diagnosis of COVID-19. This review also presents recent reports on other analytical techniques including paper spray mass spectrometry for the diagnosis of COVID-19 in clinical samples. Finally, we provide a quick reference on molecular biology and nanotechnology based analytical tools for COVID-19 diagnosis in clinical samples.

Simple hydrothermal approach for synthesis of fluorescent molybdenum disulfide quantum dots: Sensing of Cr3+ ion and cellular imaging.

Nowadays, fluorescent molybdenum disulfide quantum dots (MoS2 QDs) have proven to be potential candidates in the sensing and bioimaging areas owing to their exceptional intrinsic characteristics. Here, a simple hydrothermal strategy was explored for the preparation of MoS2 QDs using ammonium heptamolybdate and 6-mercaptopurine (6-MP) as precursors. The emission peak of MoS2 QDs was significantly quenched in the presence Cr3+ ion due to the selective surface chemistry on the surfaces of MoS2 QDs. The designed fluorescent MoS2 QDs showed a linear fluorescence quenching response with increasing concentration of Cr3+ ion (0.1-10 µM), allowing to detect Cr3+ ion even at 0.08 µM. This fluorescent MoS2 QDs were utilized for the quantification of Cr3+ ion in real samples (water and biological samples). Interestingly, the synthesized MoS2 QDs exhibited negligible cytotoxicity on NRK cells and acted as good candidates for imaging of Trichoderma viride fungal cells.

Evaluation of selected pharmaceuticals and personal care products in water matrix using ion trap mass spectrometry: A simple weighted calibration curve approach.

A novel analytical method is presented for 12 target pharmaceutical and personal care products (PPCPs), belonging to different classes like antibiotics, non-steroid anti-inflammatory drugs, parabens, UV-filters, plasticizer, and antibacterials. The method development comprises of solid-phase extraction (SPE) with lipophilic-hydrophilic material balanced Oasis HLB cartridge, followed by reverse-phase liquid chromatography interfaced to linear ion trap tandem mass spectrometry (LC-MS/MS) with electrospray ionization. Chromatographic separation was achieved with a gradient elution of 25 min run time using 5 mM ammonium acetate buffer with pH adjustment using acetic acid. In addition, cost effective organic solvent with buffer used together as the mobile phase with Chromatopak C18 column (150 mm × 4 mm, 5-µm,) in negative ionization mode. Recoveries ranged from 61.74 % to 119.89 % for most of the compounds. Matrix-matched calibration curves were used for counterbalancing the matrix effects for all the analytes, and ibuprofen D3 internal standard was used for assessing the effectiveness of extraction technique and monitoring the recovery of sample analysis. Simple empirical weighted linear regression curve technique was adopted practically for each analysis in enhancing the analyte accuracy at lower quantification level. The 1/x2 model was selected as the best suitable model for quantification of analytes, which can be evaluated by deviation from back-calculated concentration in terms of percentage relative error (%RE). Weighted calibration curves with regression value for most of the compounds were ≥ 0.98, except triclosan with a regression value ≥ 0.93. Precision showed as % relative standard deviation (%RSD) were always below 15.0 %. Accuracy-test was evaluated by the statistical one-sample t-test and no significant difference was observed between nominal and experimental value. The limit of quantification (LOQ) ranged from 3.0 ng/mL (BP1) to 1000 ng/mL (naproxen). Finally, the validated method was used for the first time to determine target analytes in surface water samples collected from Arkavathi river flowing across southern India's Bengaluru city.

Acid Oxidation of Muskmelon Fruit for the Fabrication of Carbon Dots with Specific Emission Colors for Recognition of Hg2+ Ions and Cell Imaging.

In this study, water-soluble emissive carbon dots (CDs) are effectively fabricated with specific optical properties and colors by acid oxidation of muskmelon (Cucumis melo) fruit, which are termed as C. melo CDs (CMCDs). The fluorescence properties of CMCDs were tuned by controlling the experimental conditions that allow them to emit different colors, that is, blue (B-), green (G-), and yellow (Y-) CMCDs, with different emission wavelengths at 432, 515, and 554 nm when excited at 342, 415, and 425 nm, respectively. The fabricated multicolor-emissive CDs were confirmed by various analytical techniques. The sizes of B-, G-, and Y-CMCDs were found to be ∼3.5, ∼4.3, and ∼5.8 nm, respectively. The as-prepared CMCDs display stable emissions with quantum yields of 7.07, 26.9, and 14.3% for the three CMCDs, which could act as a promising probe for the selective detection of Hg2+ ions. Upon the addition of Hg2+ ions, the fluorescence intensity of G-CMCDs at 515 nm was quenched largely than that of B- and Y-CMCDs. The spectroscopic results display that the G-CMCDs acted as a sensor for the detection of Hg2+ ions with a wide linear range from 1.0 to 25 µM (R 2 = 0.9855) with a detection limit of 0.33 µM. This method was successfully applied to detect Hg2+ ions in biological and water samples. The fabricated multicolor-emissive CMCDs possess the cell (Cunninghamella elegans, Aspergillus flavus, and Rhizoctonia solani) imaging property, suggesting the biocompatible nature for multicolor imaging of various cells.

Influence of doping ion, capping agent and pH on the fluorescence properties of zinc sulfide quantum dots: Sensing of Cu2+ and Hg2+ ions and their biocompatibility with cancer and fungal cells.

Herein, a facile one-pot synthetic method was explored for the fabrication of glutathione capped Mn2+ doped­zinc sulphide quantum dots (GSH-Mn2+-ZnS QDs) for both fluorescent detection of Cu2+ and Hg2+ ions and for fluorescence imaging of two cancer (RIN5F and MDAMB231) and fungal (Rhizopus oryzae) cells. Particularly, doping of Mn2+ into ZnS QDs nanocrystal structure resulted a great improvement in the fluorescence properties of ZnS QDs. The emission peak of undoped ZnS QDs was found at 447 nm, which is due to the large number of surface defects in the ZnS QDs nanostructures. Under identical conditions, there is a good linear relationship between the quenching of fluorescence intensity and analytes (Cu2+ and Hg2+ ions) concentration in the range of 0.005 to 0.2 mM and of 0.025 to 0.4 mM for Cu2+ and Hg2+ ions, respectively. The GSH-Mn2+-ZnS QDs exhibit least cytotoxicity against RIN5F and MDAMB231 cells, demonstrating the multifunctional applications in sensing of metal ions and biocompatibility towards cancer (RIN5F and MDAMB231) and fungal (Rhizopus oryzae) cells.

Tuning of gold nanoclusters sensing applications with bovine serum albumin and bromelain for detection of Hg2+ ion and lambda-cyhalothrin via fluorescence turn-off and on mechanisms.

Herein, fluorescent gold nanoclusters (Au NCs) were obtained by one-pot synthetic method using bovine serum albumin (BSA) and bromelain as templates. As-synthesized fluorescent Au NCs were stable and showed bright red fluorescence under UV lamp at 365 nm. The fluorescent Au NCs exhibit the emission intensity at 648 nm when excited at 498 nm. Various techniques were used such as spectroscopy (UV-visible, fluorescence, and Fourier-transform infrared), high-resolution transmission electron microscopy, and dynamic light scattering for the characterization of fluorescent Au NCs. The values of I0/I at 648 nm are proportional to the concentrations of Hg2+ ion in the range from 0.00075 to 5.0 µM and of lambda-cyhalothrin in the range from 0.01 to 10 µM with detection limits of 0.0003 and 0.0075 µM for Hg2+ ion and lambda-cyhalothrin, respectively. The practical application of the probe was successfully demonstrated by analyzing Hg2+ ion and lambda-cyhalothrin in water samples. In addition, Au NCs used as probes for imaging of Simplicillium fungal cells. These results indicated that the as-synthesized Au NCs have proven to be promising fluorescent material for the sensing of Hg2+ ion and lambda-cyhalothrin in environmental and for imaging of microorganism cells in biomedical applications.