Recent Advancements in the Field of Chitosan/Cellulose-Based Nanocomposites for Maximizing Arsenic Removal from Aqueous Environment.

Water remediation, acknowledged as a significant scientific topic, guarantees the safety of drinking water, considering the diverse range of pollutants that can contaminate it. Among these pollutants, arsenic stands out as a particularly severe threat to human health, significantly compromising the overall quality of life. Despite widespread awareness of the harmful effects of arsenic poisoning, there remains a scarcity of literature on the utilization of biobased polymers as sustainable alternatives for comprehensive arsenic removal in practical concern. Cellulose and chitosan, two of the most prevalent biopolymers in nature, provide a wide range of potential benefits in cutting-edge industries, including water remediation. Nanocomposites derived from cellulose and chitosan offer numerous advantages over their larger equivalents, including high chelating properties, cost-effective production, strength, integrity during usage, and the potential to close the recycling loop. Within the sphere of arsenic remediation, this Review outlines the selection criteria for novel cellulose/chitosan-nanocomposites, such as scalability in synthesis, complete arsenic removal, and recyclability for technical significance. Especially, it aims to give an overview of the historical development of research in cellulose and chitosan, techniques for enhancing their performance, the current state of the art of the field, and the mechanisms underlying the adsorption of arsenic using cellulose/chitosan nanocomposites. Additionally, it extensively discusses the impact of shape and size on adsorbent efficiency, highlighting the crucial role of physical characteristics in optimizing performance for practical applications. Furthermore, this Review addresses regeneration, reuse, and future prospects for chitosan/cellulose-nanocomposites, which bear practical relevance. Therefore, this Review underscores the significant research gap and offers insights into refining the structural features of adsorbents to improve total inorganic arsenic removal, thereby facilitating the transition of green-material-based technology into operational use.

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.

Effect of ZnO Nanoparticles on Growth and Biochemical Responses of Wheat and Maize.

Zinc is an essential element that is also renowned for widespread contamination and toxicity at high concentrations. The present study was carried out to analyze the responses induced by lower, as well as higher, doses of zinc (0-200 mg/L), in the form of zinc oxide nanoparticles (ZnO NPs) in wheat and maize, for a period of 21 days. Accumulation of zinc increases with increasing Zn doses in both wheat and maize, with higher doses being in wheat (121 mg/kg in root and 66 mg/kg in shoot) than in maize (95 mg/kg in root and 48 mg/kg in shoot). The activity of alpha-amylase showed increase, while that of dehydrogenase decline, in response to ZnO NPs. The length and biomass of plants and photosynthetic pigments increased slightly upon ZnO NPs supply. Malondialdehyde content showed a progressive increase in root and shoot of both plants. However, in response, antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, and catalase) showed increase up to lower concentrations (100 mg/L) of ZnO NPs but decline variably at higher levels (150-200 mg/L) in wheat and maize. The results suggest that lower supply of ZnO NPs (100 mg/L) could be stimulatory to the growth of plants and can be recommended as a Zn fertilizer source for crop production.

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.

Mitigation of Cr(VI) toxicity using Pd-nanoparticles immobilized catalytic reactor (Pd-NICaR) fabricated via plasma and gamma radiation.

Catalytic reduction of Cr(VI) to less toxic Cr(III) form using metal nanoparticles is one of the novel approaches adopted to deal with Cr toxicity. In this work, we report the fabrication of a facile, reusable, and robust Pd nanoparticles-immobilized catalytic reactor (Pd-NICaR) system using green, environment-friendly gamma radiolytic, and plasma polymerization processes. A room temperature, RF-powered plasma polymerization process was employed to functionalize a polyethylene-polypropylene (PE-PP) non-woven matrix with epoxy group containing monomer 2,3-epoxypropyl methacrylate (EPMA). EPMA-functionalized PE-PP (EPMA-f-PE-PP) substrate was subsequently used as a template for in situ generation and immobilization of Pd NPs via gamma radiolytic route. The samples were characterized using FTIR, SEM, XPS, and XRF techniques. The catalytic efficacy of Pd-NICaR towards Cr(VI) reduction, in the presence of formic acid (FA) as a reductant, was investigated spectrophotometrically, and reaction parameters were optimized at reaction temperature of 50 °C and [FA]/[Cr(VI)] = 680 to achieve catalytic reduction efficiency of 99.7% within 10 min in batch process. The system showed excellent reusability (~ 20 cycles) and storage stability (> 30 days) without substantial loss (~ 11%) of activity. Practical applicability of the robust catalytic system towards Cr(VI) toxicity mitigation was established in continuous flow mode using a fixed-bed column reactor.

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.

Synthesis of Water Dispersible Fluorescent Carbon Nanocrystals from Syzygium cumini Fruits for the Detection of Fe3+ Ion in Water and Biological Samples and Imaging of Fusarium avenaceum Cells.

In this work, water dispersible fluorescent carbon nanocrystals (NCs) were synthesized by a simple, green and low cost hydrothermal method using Syzygium cumini (jamun) as a carbon source at 180 °C for 6 h. The average size of carbon NCs was found to be 2.1 ± 0.5 nm and shown bright blue fluorescence when excited at 365 nm under UV lamp. The carbon NCs were characterized by spectroscopic (UV-visible and fluorescence, Fourier transform infrared and dynamic light scattering) and high resolution transmission electron microscopic techniques. The quantum yield of carbon NCs was found to be ~5.9 % at 438 nm emission wavelength when excited at 360 nm. It was noticed that none of the metal ions quenched the fluorescence intensity of carbon NCs at 438 nm except for Fe3+, indicating the formation of Fe3+ ion-carbon NCs complexes. The linear range was observed in the concentration range of 0.01-100 µM with the corresponding detection limits of 0.001 µM, respectively. Furthermore, the carbon NCs were used as probes for imaging of fungal (Fusarium avenaceum) cells.

Microwave assisted synthesis of tyrosine protected gold nanoparticles for dual (colorimetric and fluorimetric) detection of spermine and spermidine in biological samples.

In this work, tyrosine-protected gold nanoparticles (Tyr-Au NPs) were fabricated by one-step reduction of Au3+ ion using Tyr as a reducing and capping agent under microwave irradiation. The Tyr-Au NPs were successfully used as a dual probe for colorimetric and fluorescence turn-on assays of spermine and spermidine in biological samples. Upon addition of spermine and spermidine, the characteristic surface plasmon resonance (SPR) band of Tyr-Au NPs was red-shifted to 596 and 616nm and the emission peak (Tyr) at 410nm was gradually increased with increasing concentration of both analytes, confirming the aggregation of Tyr-Au NPs induced by spermine and spermidine, which results to restore fluorescence of Tyr on the surfaces of Au NPs. In addition, it shows high selectivity for sensitive detection of prostatic cancer biomarkers spermine and spermidine in real clinical applications with reduced sample preparations.

One-step green synthetic approach for the preparation of multicolor emitting copper nanoclusters and their applications in chemical species sensing and bioimaging.

One-step green microwave synthetic approach was developed for the synthesis of copper nanoclusters (Cu NCs) and used as a fluorescent probe for the sensitive detection of thiram and paraquat in water and food samples. Unexpectedly, the prepared Cu NCs exhibited strong orange fluorescence and showed emission peak at 600 nm, respectively. Under optimized conditions, the quenching of Cu NCs emission peak at 600 nm was linearly proportional to thiram and paraquat concentrations in the ranges from 0.5 to 1000 µM, and from 0.2 to 1000 µM, with detection limits of 70 nM and 49 nM, respectively. In addition, bioimaging studies against Bacillus subtilis through confocal fluorescence microscopy indicated that Cu NCs showed strong blue and green fluorescence signals, good permeability and minimum toxicity against the various bacteria species, which demonstrates their potential feasibility for chemical species sensing and bioimaging applications.

New Chitosan-Thiomer: An Efficient Colorimetric Sensor and Effective Sorbent for Mercury at Ultralow Concentration.

This paper describes an innovative procedure for the fabrication of a facile colorimetric sensor in one step with thiol functional group for Hg(2+) detection at trace level. The sensor was successfully synthesized via chitosan isothiouronium salt intermediate with innocuous low cost thiourea reagent under microwave irradiation. It is an innovative green approach to achieve thiol functionalization with a high degree of substitution. Thiomer was characterized by titrimetry, FTIR, (1)H NMR, elemental analysis (CHNS), and EDX for extent of modification with detail structure. The synthesized and well characterized thiomer was screened for sensor application. The sensing solution of thiomer resulted in an instantaneous sharp color change from colorless, yellow, to brown with increase in Hg(2+) concentration. Chitosan thiomer also exhibited high sensitivity and selectivity for Hg(2+) over other possible interfering ions in aqueous media. The sensing responses were visualized quantitatively with quick response, good selectivity, high sensitivity, and a low detection limit of ∼0.465 ppb by the naked eye. The same was tested with a paper strip method for technological applications. Furthermore, the as-prepared sensors also exhibited exceptional sorption potential for Hg(2+) even from ultralow concentration aqueous solution and reduced the Hg(2+) concentration from 10 ppb to the extremely low level of ∼0.04 ppb as studied by cyclic voltammetry. Thus, the proposed method is simple, promising, and rapid without any complicated modifying step and is an economical alternative to traditional Hg(2+) sensors for rapid sensor application in environmental water samples at ppb levels.

Thermodynamic parameters of U (VI) sorption onto soils in aquatic systems.

The thermodynamic parameters viz. the standard free energy (∆Gº), Standard enthalpy change (∆Hº) and standard entropy change (∆Sº) were determined using the obtained values of distribution coefficient (kd) of U (VI) in two different types of soils (agricultural and undisturbed) by conducting a batch equilibrium experiment with aqueous media (groundwater and deionised water) at two different temperatures 25°C and 50°C. The obtained distribution coefficients (kd) values of U for undisturbed soil in groundwater showed about 75% higher than in agricultural soil at 25°C while in deionised water, these values were highly insignificant for both soils indicating that groundwater was observed to be more favorable for high surface sorption. At 50°C, the increased kd values in both soils revealed that solubility of U decreased with increasing temperature. Batch adsorption results indicated that U sorption onto soils was promoted at higher temperature and an endothermic and spontaneous interfacial process. The high positive values of ∆Sº for agricultural soil suggested a decrease in sorption capacity of U in that soil due to increased randomness at solid-solution interface. The low sorption onto agricultural soil may be due to presence of high amount of coarse particles in the form of sand (56%). Geochemical modeling predicted that mixed hydroxo-carbonato complexes of uranium were the most stable and abundant complexes in equilibrium solution during experimental.