Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 31
Filter
Add more filters










Publication year range
1.
Nanoscale ; 16(19): 9558-9569, 2024 May 16.
Article in English | MEDLINE | ID: mdl-38666449

ABSTRACT

This study presents a halide exchange mediated cation exchange reaction to co-dope d- and f-block elements in CsPbX3 NPs at room temperature. Addition of MnCl2 and YbCl3 to CsPbBr3 NPs induces ion exchange reactions generating the corresponding CsPbBr3/MnCl2YbCl3 NPs. In addition to the perovskite emission, the NPs display sensitized Mn2+ and Yb3+ emissions in concert spanning the UV, visible, and NIR spectral region. Structural and spectroscopic characterizations indicate a substitutional displacement of Pb2+ by the Mn2+ and Yb3+. The identity of the host halide in modulating the ion exchange reactions was also tested. An effective perovskite host NP is presented that can be used to incorporate d-f or f-f dopant combinations to realize a gamut of dopant emission lines. A charge trapping based photophysical model is developed that focuses on rational energy alignments to predict dopant emissions semi-empirically and aids the design of optimal perovskite host-multi-dopant combinations.

2.
Chemosphere ; 355: 141820, 2024 May.
Article in English | MEDLINE | ID: mdl-38561158

ABSTRACT

Organic solvent nanofiltration (OSN) is an incipient technology in the field of organic liquid-liquid separation. The incomplete separations and complexity involved in these, forces many organic liquids to be released as effluents and the adverse effects of these on environment is enormous and irreparable. The work prominences on the complete separation of industrially significant cyclohexanone: cyclohexanol (keto-alcohol oil) and heptane: toluene mixtures. The separations of these above-mentioned organic liquid mixtures were carried out using the fabricated Lewis acid modified graphitic carbon nitride (Cu2O@g-C3N4) incorporated polyvinylidene difluoride (PVDF) composite membranes. These fabricated membranes showed a separation factor of 18.16 and flux of 1.62 Lm-2h-1 for cyclohexanone: cyclohexanol mixture and separation of heptane and toluene mixture (with heptane flux of 1.52 Lm-2h-1) showed a separation factor of 9.9. The selectivity and productivity are based on the polarity and size of the organic liquids. The role of Cu2O@g-C3N4 is influencing the pore size distribution, increased divergence from solubility parameters, polarity, solvent uptake and porosity of the composite membranes. The developed composite membranes are thus envisioned to be apt for a wide range of liquid-liquid separations due to its implicit nature.


Subject(s)
Cyclohexanols , Cyclohexanones , Heptanes , Solvents , Toluene
3.
Environ Sci Pollut Res Int ; 31(1): 167-190, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38044404

ABSTRACT

Magnetic nanoparticle-incorporated metal organic frameworks (MOF) are potential composites for various applications such as catalysis, water treatment, drug delivery, gas storage, chemical sensing, and heavy metal ion removal. MOFs exhibits high porosity and flexibility enabling guest species like heavy metal ions to diffuse into bulk structure. Additionally, shape and size of the pores contribute to selectivity of the guest materials. Incorporation of magnetic materials allows easy collection of adsorbent materials from solution system making the process simple and cost-effective. In view of the above advantages in the present review article, we are discussing recent advances of different magnetic material-incorporated MOF (Mg-MOF) composite for application in photocatalytic degradation of dyes and toxic chemicals, adsorption of organic compounds, adsorption of heavy metal ions, and adsorption of dyes. The review initially discusses on properties of Mg-MOF, different synthesis techniques such as mechanochemical, sonochemical (ultrasound) synthesis, slow evaporation and diffusion methods, solvo(hydro)-thermal and iono-thermal method, microwave-assisted method, microemulsion method post-synthetic modification template strategies and followed by application in waste water treatment.


Subject(s)
Metal-Organic Frameworks , Metals, Heavy , Nanostructures , Water Purification , Metal-Organic Frameworks/chemistry , Adsorption , Water Purification/methods , Ions , Coloring Agents , Magnetic Phenomena
4.
Langmuir ; 39(31): 11099-11107, 2023 08 08.
Article in English | MEDLINE | ID: mdl-37490749

ABSTRACT

In the realm of electrochemical sensor application, the development and fabrication of semiconducting metal oxides with the integration of conducting polymers for the trace-level detection of pharmaceutical medicines garnered considerable interest. Herein, we reported facile cadmium oxide decorated with polypyrrole nanotubes fabricated on a glassy carbon electrode (CdO@PPy/GCE) for efficient determination of antihistamine drug promethazine hydrochloride (PMH). The as-synthesized CdO@PPy composite was characterized by various analytical tools like X-ray powder diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Furthermore, the electrocatalytic activity of the modified electrode for PMH detection was examined by voltammetry and amperometric methods, and the modified electrode exhibited lower charge transfer resistance compared to the bare GCE. Under the optimized condition, the fabricated electrode shows a wide linear range (50-550 µM), better sensitivity (0.13 µAµM-1 cm-2), low detection limit (10.83 nM) (S/N = 3), and excellent selectivity and reproducibility toward PMH detection. Moreover, the modified GCE depicted eminent practical ability for PMH detection in lake water and pharmaceutical tablets.


Subject(s)
Nanotubes , Polymers , Polymers/chemistry , Promethazine , Pyrroles/chemistry , Reproducibility of Results , Histamine Antagonists , Pharmaceutical Preparations , Electrodes , Limit of Detection
5.
J Mater Chem B ; 11(10): 2184-2190, 2023 03 08.
Article in English | MEDLINE | ID: mdl-36779786

ABSTRACT

Despite the excellent optoelectronic properties exhibited by CsPbBr3 QDs (PQDs) for sensing applications, their poor resistance to water does not allow their utilization as probes to detect analytes in aqueous media. The present work provides water soluble PQDs (dispersed in water) prepared by an appropriate phase engineering of the ligand. The dicarboxylate functional ligands at a particular pH allow the protonated state to form solvated carboxyl dimers, which interconnects PQDs, thus avoiding Ostwald ripening and enhancing the photoluminescence quantum yield (PLQY). As a proof of concept, this probe was applied to detect bioamines in water, namely histamine, hexamethylenediamine, phenethylamine, dopamine and thiamine. The probe is highly selective to histamine at concentrations below 500 nM and this selectivity of histamine over dopamine is very interesting and rarely reported. More importantly, this work offers a standard protocol for transferring PQDs from the organic to aqueous phase, for the detection of such biomolecules in water.


Subject(s)
Quantum Dots , Water , Dopamine , Histamine
6.
ACS Omega ; 7(49): 44495-44506, 2022 Dec 13.
Article in English | MEDLINE | ID: mdl-36530224

ABSTRACT

Liquid-liquid separation is crucial in the present circumstances. Substitution of the conventional types of separation like distillation and pervaporation is mandatory due to the high energy requirement of the two. The separation of organic mixtures has a huge potential in industries such as pharmaceutical, fine chemicals, fuels, textile, papers, and fertilizers. Membrane-affiliated separations are one of the prime techniques for liquid-liquid separations. Organic solvent nanofiltration, solvent-resistant nanofiltration, and ultrafiltration are a few methods through which organic liquid-liquid separation can be attained. Implementation of such a technology in chemical industries reduces the time consumption and is cost efficient. Even though a lot of research has been done, attention is needed in the field of organic-liquid separation aided by membranes. In this review, various membranes used for organic mixture separations such as polar-nonpolar, polar-polar, and nonpolar-nonpolar are discussed with a focus on membrane materials, additives, separation theory, separation type, experimental setup, fouling mitigation, surface modification, and major challenges. The review also offers insights and probable solutions for existing problems and also discusses the scope of research to be undertaken in the future.

7.
ACS Omega ; 7(48): 43346-43363, 2022 Dec 06.
Article in English | MEDLINE | ID: mdl-36506161

ABSTRACT

Despite the advantages of high contaminant removal, operational flexibility, and technical advancements offered, the undesirable fouling property of membranes limits their durability, thus posing restrictions on their usage. An enormous struggle is underway to conquer this major challenge. Most of the earlier reviews include the basic concepts of fouling and antifouling, with respect to particular separation processes such as ultrafiltration, nanofiltration, reverse osmosis and membrane bioreactors, graphene-based membranes, zwitterionic membranes, and so on. As per our knowledge, the importance of nanofiber membranes in challenging the fouling process has not been included in any record to date. Nanofibers with the ability to be embedded in any medium with a high surface to volume ratio play a key role in mitigating the fouling of membranes, and it is important for these studies to be critically analyzed and reported. Our Review hence intends to focus on nanofiber membranes developed with enhanced antifouling and biofouling properties with a brief introduction on fabrication processes and surface and chemical modifications. A summary on surface modifications of preformed nanofibers is given along with different nanofiller combinations used and blend fabrication with efficacy in wastewater treatment and antifouling abilities. In addition, future prospects and advancements are discussed.

8.
ACS Appl Mater Interfaces ; 14(34): 38471-38482, 2022 Aug 31.
Article in English | MEDLINE | ID: mdl-35975683

ABSTRACT

Perovskite quantum dots (PQDs) offer high photoluminescence quantum yields; however, due to their limited stability in aqueous media, to date their utilization in biomedical applications has been limited. The present work demonstrates highly fluorescent and stable aqueous PQDs that were synthesized using a facile engineered phase transfer method. Ligands were engineered to have a dual functionality, i.e., they could simultaneously mediate the strong binding of PQDs and the interactions with water molecules. The resultant water-soluble PQDs demonstrated robust structural and optical properties. The extracted aqueous PQDs remained stable in pellet form for 8 months, which was the entire test duration. Notably, 100% of their fluorescence was also retained. As a proof-of-concept experiment, the water-soluble PQDs were successfully tagged to polyclonal antibodies and used to image Escherichia coli cells in aqueous media. No structural or optical disturbance in PQDs was detected throughout the process. This work marks the beginning of the use of nonpolymeric aqueous PQDs and shows their strong potential to be used in biological applications.


Subject(s)
Quantum Dots , Calcium Compounds/chemistry , Fluorescence , Oxides , Quantum Dots/chemistry , Titanium , Water/chemistry
9.
ACS Omega ; 7(11): 9674-9683, 2022 Mar 22.
Article in English | MEDLINE | ID: mdl-35350350

ABSTRACT

Nitrogenated graphene oxide-decorated copper sulfide nanocomposites (Cu x S-NrGO, where x = 1 and 2) are designed to be incorporated in polysulfone (PSF) membranes for effective fouling resistance of PSF membranes and their dye removal capacity. The developed membranes possess more hydrophilicity and an enhancement in pure water flux (PWF). Also, the highest bovine serum albumin (BSA) rejection of 89% was observed when compared to membranes with pristine PSF (5 L/m2 h PWF and 88% BSA rejection) and CuS-incorporated PSF membranes (14 L/m2 h PWF and 83% BSA rejection) because of N doping and enhanced permeability. It is also found that the Cu x S-NrGO-incorporated PSF membranes exhibited a significantly higher fouling resistance, a larger permeate flux recovery ratio (FRR) of nearly 82%, and a congo red dye rejection of 93%. Cu x S-NrGO nanoparticles thus demonstrate the potential efficacy of enhancing the hydrophilicity, leading to a better flux, dye removal capacity, and antifouling capacity with a very high FRR value of 82% because of a strong interaction between the N-active sites of the NrGO, Cu x S, and polysulfone matrix, and negligible leaching of nanoparticles is observed.

10.
ACS Omega ; 7(6): 4859-4867, 2022 Feb 15.
Article in English | MEDLINE | ID: mdl-35187306

ABSTRACT

Nanostructured polymeric membranes are of great importance in enhancing the antifouling properties during water filtration. Nanomaterials with tunable size, morphology and composition, surface modification, and increased functionality provide considerable opportunities for effective wastewater treatment. Thus, in this work, an attempt has been made to use spinel-structured MnCo2O4 as a nanofiller in the fabrication of nanostructured polysulfone (PSF) mixed matrix membranes and is investigated in terms of morphology, hydrophilicity, permeability, protein and natural organic matter separation, dye removal, and, finally, antifouling properties. The MnCo2O4 nanomaterials are synthesized and characterized via X-ray diffraction and field emission scanning electron microscopy and are loaded into a membrane matrix with varied concentrations (0 to 1.5 wt %). PSF nanocomposite membranes are prepared via a nonsolvent-induced phase-separation process. The results show an enhancement in hydrophilicity, porosity, and permeability with respect to the modified nanocomposite membranes because of oxygen-rich species in the membrane matrix, which increases affinity toward water. It was also found that the modified membranes display remarkably greater pure water flux (PWF) (220 L/m2 h), higher Congo red rejection coefficient (99.86%), higher humic acid removal (99.81%), higher fouling resistance, and a significant flux recovery ratio (FRR) (88%) when tested with bovine serum albumin protein when compared to a bare PSF membrane (30 L/m2 h PWF and 35% FRR). This is because the addition of MnCo2O4 nanoparticles into the polymeric casting solution yielded tighter PSF membranes with a denser skin layer and greater selectivity. Thus, the enhanced permeability, greater rejection coefficient, and antifouling properties show the promising potential of the fabricated PSF-spinel nanostructured membrane to be utilized in membrane technology for wastewater treatment.

11.
ACS Appl Mater Interfaces ; 13(48): 57264-57273, 2021 Dec 08.
Article in English | MEDLINE | ID: mdl-34813271

ABSTRACT

Perovskite quantum dots (PQDs) exhibit exceptional fluorescence property and are potential candidates for fluorescent metal-ion sensors. The present work shows the presence of inner filter effect (IFE) in perovskite sensing systems and its significance in enhancing the detection limits. Two different sensing systems (with a different extent of IFE), one with simple long-chain monodentate ligand-capped PQDs and the other with short-chain bidentate ligand capped PQDs, were developed toward sensing Co2+. The fluorescence quenching mechanism is elucidated and is observed to be a combination of Forster resonance energy transfer (FRET) and IFE. The electrostatic interaction of donor (D) with acceptor (A) and its distance for energy transfer was appropriate and was well within the requirement for a good energy transfer from PQDs (donor) to Co2+ ions (acceptor) facilitating partial FRET. Also, the spectral overlap of absorption of excited and emitted radiation (of PQDs) with that of Co2+ allows a significant amount of IFE. PQDs were successfully modified for lesser spectral overlap with reduced IFE. The reduction in IFE adversely drops the detection levels from 0.733 × 10-7 to 0.7970 × 10-6 on modification. This work provides insights into the design and development of high sensing perovskite probes with manipulation of IFE and also shows the importance of IFE to be considered during the study of such sensing systems, which has been neglected so far in perovskite systems.

12.
J Colloid Interface Sci ; 603: 758-770, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34229118

ABSTRACT

Building compatible surface on perovskite quantum dots (PQDs) for applications like sensing analytes in aqueous medium is highly challenging and if achieved by simple means can revolutionize disease diagnostics. The present work reports the surface engineering of CsPbBr3 QDs via "simple ligand exchange process" to achieve water-compatible QDs towards detection of biomolecules. The monodentate oleic acid ligand in CsPbBr3 QDs is exchanged with dicarboxylic acid containing (bidentate) ligands such as folic acid (FA), ethylenediamine tetra-acetic acid (EDTA), succinic acid (SA) and glutamic acid (GA) to develop an efficient water-compatible PQD-ligand system. optical and theoretical studies showed the existence of a stronger binding between the perovskite and succinic acid ligand as compared to oleic acid (OA) and all other ligands. Replacement of OA with SA and retention of crystal structure is validated using spectroscopic and microscopic tools. It is observed that SA ligands facilitate better electronic coupling with PQDs and show significant improvement in fluorescence and stability. Further N-Hydroxy succinimide (NHS), which is a well-known compound to activate carboxyl groups, is used to bind onto SA PQDs as multidentate ligand, to form water stable PQDs. SA PQDs react with NHS (in water) to form multidentate ligand passivated PQDs that show very high photoluminescence (PL) as compared to OA PQDs in toluene. This also results in the formation of an NHS ester that allows bioconjugation with PQDs. This simple probe in water is further utilized for sensing a highly hydrophilic bovine serum albumin (BSA) protein as a model target to demonstrate the potential and effectiveness of this process to create compatible QDs for the successful conjugation of biomolecules. Although the focus of this work is to demonstrate bioconjugation and not achieving higher sensitivity levels, the intrinsic sensing level of these compatible QDs towards BSA shows a detection limit of 51.47 nM, which is above par with other reports in literature.


Subject(s)
Quantum Dots , Animals , Calcium Compounds , Cattle , Ligands , Oxides , Serum Albumin, Bovine , Titanium
13.
Langmuir ; 36(26): 7332-7344, 2020 07 07.
Article in English | MEDLINE | ID: mdl-32510224

ABSTRACT

The rapid, ultralow detection, degradation, and complete removal of pesticides demand the design of potential substrates. Herein, we discussed gold nanorods (Au NRs) as the potential substrate for the naked eye detection and degradation of two common and broad-spectrum pesticides, chlorpyrifos (CPF) and malathion (MLT), up to 0.15 ppt concentration within 2 min. Under certain environmental conditions, both the pesticides degraded and adsorbed on the surface of Au NRs. The degraded moieties of CPF and MLT on the surface of Au NRs formed side-to-side and end-to-end interactions, respectively, leading to a long-range assembly. This shows that no external agent is required, and only CPF and MLT analytes are quite enough for the formation of assembly of Au NRs. Assembly of Au NRs is confirmed by transmission electron microscopy (TEM) analysis, and degradation is supported by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and gas chromatography-mass spectrometry (GC-MS) analyses. Au NRs were recovered and reused for four consecutive cycles. The fast and ultralow detection of pesticides demonstrates that Au NRs are a potential substrate for the detection and degradation of pesticides.

14.
Mikrochim Acta ; 187(3): 189, 2020 02 26.
Article in English | MEDLINE | ID: mdl-32103346

ABSTRACT

An electrochemical sensor is described for the determination of catechol (CT) based on the nanocomposite of lanthanum cobaltite supported on graphene nanosheets (LaCo/GNS). The nanocomposite was systematically examined by various analytical and spectroscopic methods. The LaCo/GNS-modified electrode exhibites good electrochemical activity towards CT determination compared to other modified and unmodified electrodes. The electrochemical signal was acquired at a redox potential of 0.21 (Epa) and 0.17 (Epc) Volt (vs. Ag/AgCl). The proposed electrode exhibits low detection limit (1.0 nM), wide working range (0.009-132 µM), and good sensitivity (5.68 µA µM-1 cm-2). The electrochemical nanoprobe has good selectivity over potentially interfering compounds. The electrochemical sensor was applied to the analysis of environmental samples with acceptable recovery. Graphical abstractSchematic representation of electrochemical determination of catechol in the environmental sample analysis using lanthanum cobaltite supported on graphene nanosheets.


Subject(s)
Catechols/chemistry , Electrochemical Techniques/methods , Graphite/chemistry , Lanthanum/chemistry , Minerals/chemistry , Nanocomposites/chemistry
15.
J Photochem Photobiol B ; 204: 111799, 2020 Mar.
Article in English | MEDLINE | ID: mdl-32018156

ABSTRACT

CdSe/CdS core shelled quantum dots (QDs) were prepared by colloidal synthesis using a binary ligand system and a non-coordinating, reusable solvent n-octadecane (nOD). Both the synthesis of CdSe and CdSe/CdS core shelled quantum dots were achieved by hot injection technique at much lower temperatures than reported earlier. The use of binary ligand facilitated enough nucleation and growth. Red shift in absorption spectra, an enhanced crystallite and particle size is evidenced by XRD and TEM respectively, confirming the formation of core shell structure of CdSe/CdS. The synthesized core shells exhibited high fluorescence intensity, long term stability and good mono dispersion, making it a potential material for bio-imaging and sensing. Core shell QDs were modified with mercapto propionic acid (MPA) to impart aqueous solubility. Studies on cytotoxicity of shelled QDs reveal good bio compatibility with a very minimum toxicity of IC50 = 20 µg/L. These QDs were used for sensing E. coli. Ordinary glass slide, modified using plasma etching is surface modified through APTES aiding conjugation of antibodies. Anti- E. coli polyclonal antibody on glass matrix (slide) and antibody conjugated QDs were used for detection of E. coli in a typical sandwich model. The excellent optical transparency of glass and high emission of QDs lead to detection of E.coli with a limit of detection of 50 CFU/mL.


Subject(s)
Escherichia coli/drug effects , Glass/chemistry , Quantum Dots/chemistry , Animals , Cadmium Compounds/chemistry , Cell Line , Cell Survival/drug effects , Mice , Microscopy, Fluorescence , Quantum Dots/toxicity , Selenium Compounds/chemistry , Sulfides/chemistry , Surface Properties
16.
Ecotoxicol Environ Saf ; 190: 110098, 2020 Mar 01.
Article in English | MEDLINE | ID: mdl-31901811

ABSTRACT

Prostate cancer is one of the primary causes of death around the world. As an important drug, flutamide has been used in the clinical diagnosis of prostate cancer. However, the over dosage and improper discharge of flutamide could affect the living organism. Thus, it necessary to develop the sensor for detection of flutamide with highly sensitivity. In this paper, we report the synthesis of lanthanum cobaltite decorated halloysite nanotube (LCO/HNT) nanocomposite prepared by a facile method and evaluated for selective reduction of flutamide. The as-prepared LCO/HNT nanocomposite shows the best catalytic performance towards detection of flutamide, when compared to other bare and modified electrodes. The good electrochemical performance of the LCO/HNT nanocomposite modified electrode is ascribed to abundant active sites, large specific surface area and their synergetic effects. Furthermore, the LCO/HNT modified electrode exhibits low detection limit (0.002 µM), wide working range (0.009-145 µM) and excellent selectivity with remarkable stability. Meaningfully, the developed electrochemical sensor was applied in real environmental samples with an acceptable recovery range.


Subject(s)
Environmental Pollutants/analysis , Flutamide/analysis , Lanthanum/chemistry , Nanocomposites/chemistry , Catalysis , Clay , Electrochemical Techniques/methods , Electrodes , Graphite/chemistry , Humans , Limit of Detection , Minerals , Nanotubes/chemistry
17.
ACS Appl Mater Interfaces ; 11(31): 27780-27787, 2019 Aug 07.
Article in English | MEDLINE | ID: mdl-31266296

ABSTRACT

Hydrogen production by photochemical and electrochemical means is an important area of research related to renewable energy. 2D nanomaterials such as C3N4 and MoS2 have proven to be active for the hydrogen evolution reaction (HER). Phosphorene, a mono-elemental 2D layer of phosphorus, is known to catalyze the HER, but the activity is marginal. The use of phosphorene is also limited by its ambient instability. We have been able to prepare covalently cross-linked nanocomposites of phosphorene with MoS2 as well as MoSe2. The phosphorene-MoS2 nanocomposite shows excellent photochemical HER activity yielding 26.8 mmol h-1 g-1 of H2, while only a negligible amount is produced by the physical mixture of phosphorene and MoS2. The phosphorene-MoS2 composite also displays high electrochemical HER activity with an onset overpotential of 110 mV, close to that of Pt. The enhanced HER activity of the phosphorene-MoS2 nanocomposite can be attributed to the ordered cross-linking of the 2D sheets, increasing the interfacial area as well as the charge-transfer interaction between phosphorene and MoS2 layers. The phosphorene-MoSe2 nanocomposite also exhibits good photochemical HER activity.

18.
Spectrochim Acta A Mol Biomol Spectrosc ; 223: 117291, 2019 Dec 05.
Article in English | MEDLINE | ID: mdl-31284241

ABSTRACT

The study demonstrates the fabrication of test strips made from newly synthesized ortho-Vanillin based colorimetric chemosensor (probe P) that could be employed as field deployable tool for rapid and naked eye detection of Cu2+. Upon addition of Cu2+ to the chemosensor, it exhibits rapid pink color from colorless and can be easily seen through the naked eye. This probe exhibits a remarkable colorimetric "ON" response and the absorbance intensity of the probe enhances significantly in presence of Cu2+. The sensing mechanism has been deduced using FTIR, XPS, LCMS and DFT studies. The binding mechanism of the probe to Cu2+ was substantiated by DFT studies. HOMO of the probe suggests that a high electronic density resides on O, N atoms and thus these are the favorable binding site for the metal ions. Study revealed that the P + Cu2+ complex is -35.64 eV more stable than individual reactants. The Cu2+ binds to the probe in 1:1 stoichiometry with a binding constant of 2.6 × 104 M-1 as calculated by Job's plot and Benesi-Hildebrand plot. The chemosensor shows 1.8 × 10-8 M detection limit, which is considerably lesser than that of the WHO admissible limit of [Cu2+] in drinking water. Possible interfering ions namely Ca2+, Mg2+, Fe2+, Co2+, Ni2+, Cd2+, Hg2+, Mn2+, Al3+ and Cr3+ do not show any appreciable interference in the colorimetric response of the probe towards Cu2+. Particularly, the colorimetric "ON-OFF-ON" responses are proved to be repeated over 5 times by the sequential inclusion of Cu2+ and S2-. Sensitivity of the probe in real-time water and blood samples is found at par with results with AAS and ICP-OES techniques. Further, the reversibility of the probe and the easy fabrication of deployable strips for real-field naked eye detection of Cu2+ suggest importance of synthesized probe.

19.
Analyst ; 144(13): 3999-4005, 2019 Jun 24.
Article in English | MEDLINE | ID: mdl-31172144

ABSTRACT

Micrococcal nuclease (MNase) is an extracellular endonuclease of Staphylococcus aureus (S. aureus). It digests single stranded nucleic acid. The presence of MNase is the gold standard to identify S. aureus and its content. The present study reports the ultrahigh sensitive and selective fluorescence platform for MNase detection, designed and developed based on the surface energy transfer mechanism. A "proof of concept" is being developed based on monoclonal antibody-conjugated quantum dots (mAb-QDs), wherein mAb-QDs act as donors and graphene oxide (GO) acts as an acceptor. mAb-QDs in close proximity to GO undergo adsorption due to weak affinity between them and this results in fluorescence quenching by the transfer of surface energy from mAb-QDs to GO. During sensing, a much stronger affinity of mAb-QDs towards MNase inhibits the energy transfer to GO and this allows the regaining of fluorescence. Immobilized mAb-QDs on nitrocellulose membrane strips were fabricated and tested for "ON-OFF-ON" sensing of MNase. The limit of detection for fluorescence based assay and strips is found to be 0.3 ng mL-1 and 0.5 ng mL-1, respectively. The developed strips were applied on real samples for the detection of S. aureus.


Subject(s)
Fluorescent Dyes/chemistry , Graphite/chemistry , Micrococcal Nuclease/analysis , Quantum Dots/chemistry , Staphylococcus aureus/chemistry , Antibodies, Monoclonal/chemistry , Biosensing Techniques/methods , Collodion/chemistry , Fluorescence Resonance Energy Transfer/methods , Limit of Detection , Membranes, Artificial , Nanocomposites , Proof of Concept Study , Sensitivity and Specificity , Staphylococcus aureus/enzymology
20.
Biosens Bioelectron ; 134: 24-28, 2019 Jun 01.
Article in English | MEDLINE | ID: mdl-30953872

ABSTRACT

Glucose oxidase mimicking nickel-based porous structures with organic anchors are developed as cheap and reliable electrochemical sensors for the quantitative detection of glucose. A series of sterically and electronically modulated, air- and moisture-stable half-sandwich nickel(II) NHC complexes were prepared and characterized. Under the optimized electrocatalytic conditions, the nickel complex immobilized glassy carbon electrodes (GCEs) displayed high sensitivity (0.663, 1.280, 1.990 and 0.182 µA/µM) towards glucose detection, which is much higher than that of 3D porous nickel networks. The limit of detection of modified GCEs is found in the range 1.56-2.09 µM with much wider linear sensing range, and having a catalytic rate constant of 0.273 × 103 M-1s-1. Finally, the selectivity of the modified GCEs towards glucose in presence of other blood constituents was also evaluated.


Subject(s)
Biosensing Techniques/methods , Blood Glucose/analysis , Coordination Complexes/chemistry , Coumarins/chemistry , Methane/analogs & derivatives , Nickel/chemistry , Biomimetic Materials/chemistry , Electrochemical Techniques/methods , Electrodes , Glucose Oxidase/chemistry , Humans , Methane/chemistry , Models, Molecular , Oxidation-Reduction
SELECTION OF CITATIONS
SEARCH DETAIL
...