Showing papers in "New Journal of Chemistry in 2018"
TL;DR: In this article, a green method using Malus domestica leaf extract has been used to synthesize nanoparticles of copper and silver for in vitro study, and the synthesized nanoparticles have shown Surface Plasmon Resonance maxima (SPR) at 335 and 440 nm, respectively.
Abstract: The reactivity of metallic and bimetallic nanoparticles of copper and silver towards in vitro study has been quantitatively investigated. Here, we report an easy synthesis of nanoparticles by the green method using Malus domestica leaf extract, which acts as a good stabilizing agent. The synthesized CuO and Ag–CuO nanoparticles have shown Surface Plasmon Resonance maxima (SPR) at 335 and 440 nm, respectively. The particles are spherical and crystalline in nature with average sizes between 18 and 20 nm. The Malus domestica leaf-capped nanoparticles have exhibited interesting antibacterial activity with both Gram-positive and Gram-negative bacteria at microgram concentrations. The antioxidant activity of the synthesized nanoparticles has also been measured on the basis of the free radical scavenging activity by the DPPH (1,1-diphenyl 2-picrylhydrazyl) method. Moreover, the DNA cleavage activities of the synthesized nanoparticles have been screened by agarose gel electrophoresis using the E. coli pBR322 plasmid as a target. Hence. owing to the biologically active nature of the synthesized nanoparticles, these greenly synthesized NPs act as a potent therapeutic agent.
128 citations
TL;DR: A green synthetic approach for the synthesis of water-soluble fluorescent CQDs via a simple one-step hydrothermal treatment using Tamarindus indica leaves for the first time was reported in this paper.
Abstract: Herein, we report a green synthetic approach for the synthesis of water-soluble fluorescent CQDs via a simple one-step hydrothermal treatment using Tamarindus indica leaves for the first time. The prepared CQDs show an excitation-dependent behavior in the range from 260 to 400 nm with a high QY of approximately 46.6%. Further, the prepared CQDs serve as a very sensitive nanoprobe for the turn-off sensing of Hg2+ with a minimum LOD as low as 6 nM in the dynamic range from 0 to 0.1 μM. The attractiveness of the present sensing system is that it further acts as a turn-on sensor for GSH detection with good selectivity. The feasibility of the present sensing system is also examined using pond water samples for the detection of Hg2+. Thus, the present sensing system is reliable for sensing and several another analytical applications.
116 citations
TL;DR: In this article, a microwave assisted one-pot multicomponent reaction using MgO NPs as a heterogeneous, mild and reusable catalyst was proposed for the synthesis of steroidal pyridines.
Abstract: The present study reports a highly efficient and green synthetic route for the synthesis of steroidal pyridines. The synthetic methodology involves a microwave-assisted one-pot multicomponent reaction using MgO NPs as a heterogeneous, mild and reusable catalyst. The synthesized MgO NPs were characterized by FTIR, TGA/DTA and XRD analyses. The remarkable features of this protocol include simple operational procedure, shorter reaction profiles, mild reaction conditions, minimal chemical waste and economic viability. The recyclability of the catalyst and high yield of products make the proposed method a sustainable alternative.
107 citations
TL;DR: In this paper, the authors reported the high-yield synthesis of lignin nanoparticles in different media, i.e., castor oil (CO), ethylene glycol (EG) and water (W), and evaluated their effect on the size and morphology of the LNP.
Abstract: The conversion of micro lignin to lignin nanoparticles (LNP) and their application in engineering and technology are potential steps towards global sustainability because lignin is obtained from industrial and agricultural waste and can be used in green chemistry. In the present study, we report the high-yield synthesis of lignin nanoparticles in different media, i.e., castor oil (CO), ethylene glycol (EG) and water (W) and evaluate their effect on the size and morphology of the LNP. The syntheses of LNP cover 9 out of 12 of the green chemistry principles; the synthesis was carried out via acid precipitation in a polyol medium, which acts as a stabilizing agent. From the results of the TEM, DLS, and SEM studies, it was observed that ≈15–20 nm LNP were successfully formed and spherical morphologies were observed when EG and CO were used as solvents. Furthermore, the anticorrosive behaviour of these nanoparticles was evaluated; the LNP acted as anticorrosive nanofillers for the protection of carbon steel (CS) in stringent corrosive conditions and was dispersed in an epoxy matrix to formulate epoxy nanocomposite coatings. Physicomechanical and electrochemical impedance spectroscopy (EIS) studies suggest that LNP-dispersed epoxy coatings potentially protect the underlying materials and show better protection as compared to the bare epoxy coatings.
99 citations
TL;DR: In this article, Samarium-doped ZnO nanoparticles (1, 3, and 5%) were synthesized by a gel-combustion route and their application as an efficient photocatalyst for the degradation of Malachite green (MG) dye is demonstrated.
Abstract: Samarium-doped ZnO nanoparticles (1%, 3%, and 5%) were synthesized by a gel-combustion route and their application as an efficient photocatalyst for the degradation of Malachite green (MG) dye is demonstrated. These nanoparticles were characterized by spectroscopic techniques (UV-vis and photoluminescence), micrograph techniques (SEM and TEM), X-ray diffraction, and energy dispersive X-ray, in order to evaluate their optical and structural properties, particle size distribution, and morphology. The UV-vis spectroscopic studies indicated that Sm doping increased the visible light absorption ability of the Sm-doped ZnO nanoparticles and a redshift for the Sm-doped ZnO nanoparticles appeared when compared to ZnO nanoparticles. An enhancement in the optical absorption of the Sm-doped ZnO nanoparticles indicated that it can be used as an efficient photocatalyst under a visible light irradiation. The effect of tert-butyl alcohol and disodium salt of ethylenediaminetetraacetic acid as the scavengers in the photocatalysis process revealed that hydroxyl radicals (˙OH) and holes (h+) were the reactive species responsible for the degradation of MG. The degradation mechanism has been proposed for the degradation of MG dye under the visible light irradiation. The recyclability of the Sm-doped ZnO nanoparticles for the MG dye degradation is also demonstrated.
98 citations
TL;DR: In this paper, 1-(2-pyridyl)-2-thiourea and 2-(imidazol-2-yl)-pyridine (IP) are described as inhibitors of mild steel corrosion in acidic medium based on investigations such as weight loss tests, potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS).
Abstract: 1-(2-Pyridyl)-2-thiourea (TP) and 2-(imidazol-2-yl)-pyridine (IP) are described here for the first time as inhibitors of mild steel corrosion in acidic medium based on investigations such as weight loss tests, potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS). The experimental results revealed that 1-(2-pyridyl)-2-thiourea and 2-(imidazol-2-yl)-pyridine are effective corrosion inhibitors for mild steel in acidic medium, and their maximum corrosion inhibition efficiencies at 4 × 10−4 M are 93.57% and 96.66%, respectively. TP and IP are determined as mixed-type inhibitors based on polarization studies, and their adsorption on the mild steel surface follows the Langmuir adsorption isotherm and physical adsorption is dominant. The formation and characteristics of the protective layer on the steel surface were verified by scanning electrochemical microscopy (SECM), UV-visible spectroscopy, FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS) methods. Besides, the correlation between the inhibition efficiency and the molecular structure of inhibitors was theoretically studied via quantum chemical calculations.
95 citations
TL;DR: In this paper, the authors have explored electrochemically synthesized nanostructures of free standing NiCo2O4@NiCo2 o4 composite electrode interconnected hierarchical nanoplates, and NiCo 2O4 connected hierarchical nanowires were directly grown on a high conductivity Ni foam substrate as an electrode for supercapacitor applications through a cost effective and simple chemical bath deposition method.
Abstract: Currently, enormous attention is being paid to the difficult design and synthesis of hierarchical nanosheet structures for high-performance supercapacitors. In the present study, we have explored electrochemically synthesized nanostructures of free standing NiCo2O4@NiCo2O4 composite electrode interconnected hierarchical nanoplates, and NiCo2O4 connected hierarchical nanowires were directly grown on a high conductivity Ni foam substrate as an electrode for supercapacitor applications through a cost effective and simple chemical bath deposition method. The electrochemical properties were investigated via cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy studies. This optimized NiCo2O4@NiCo2O4 nanoplate electrode delivered a remarkable specific capacitance of 2800 F g−1 at a current density of 35 A g−1, which is higher than that of the NiCo2O4 nanowire electrode (1200 F g−1 at 35 A g−1) in 3 M KOH aqueous solution, with good electrochemical and superior cycling life properties because of its higher conductivity, broad surface area and the mesopores on its walls. The NiCo2O4@NiCo2O4 nanoplate composite electrode is directly grown on the high conductivity Ni foam substrate with NiCo2O4 nanowires to support efficient electrocatalytic oxidation reactions. The mesoporous features of the NiCo2O4@NiCo2O4 nanoplate electrode enhance the properties through fast electron/ion transfer and enhance the utilization of the electrode material and large number of electroactive sites. All these results indicate that the NiCo2O4@NiCo2O4 nanoplate composite electrode would be a promising positive electrode material for flexible electrochemical capacitors.
93 citations
TL;DR: In this paper, a flower-like architecture of Bi2S3/ZnO heterostructures was successfully synthesized by a facile in situ generation method, which showed enhanced visible-light absorption and charge separation efficiency of photoinduced electron-hole pairs.
Abstract: Fabrication of heterostructures is considered as one of the effective strategies to improve photocatalytic performance for organic pollutant degradation and hydrogen production under solar light irradiation. Here, Bi2S3/ZnO heterostructures with a flower-like architecture have been successfully synthesized by a facile in situ generation method. The as-synthesized Bi2S3/ZnO heterostructures showed enhanced visible-light absorption and charge separation efficiency of photoinduced electron–hole pairs. This heterojunction exhibits 3 fold enhancement in organic pollutant degradation and 2.7 fold enhancement in photocatalytic hydrogen generation under visible irradiation compared to rod-shaped Bi2S3. The high current gain (ca. 8.79) and low photocorrosion in photoelectrochemical water splitting reveal the superior photocatalytic activity of the heterojunction under visible light. The superior photocatalytic activities are attributed to the synergetic effects of ZnO nanoparticles and rod-shaped Bi2S3 in the Bi2S3/ZnO heterostructures, which result in fast separation and slow recombination of photoinduced electron–hole pairs. The reusability and stability of the photocatalysts has been checked by recycling experiments. X-ray diffraction and scanning electron microscopy reveal that the structure and morphology of the heterostructures remain unchanged after photocatalytic cycling tests. The visible light active catalysts have potential for efficient solar light harvesting and overall water splitting. This work demonstrates the potential use of heterostructures as a highly efficient photocatalyst for dye degradation and hydrogen production under visible light irradiation.
91 citations
TL;DR: This paper presents the recent progress in fabricating intelligent chitosan hydrogels and focuses on the relationship between the structural characteristics and the corresponding functions of the intelligenthydrogels.
Abstract: Knowledge of the structure of hydrogels and the mechanism of gelation of intelligent hydrogels is essential to designing bioinspired hydrogels. As one of the raw materials in hydrogels, chitosan has been highly pursued due to the polymer's biocompatibility, biodegradability and low toxicity. The biomimetic principles for preparing intelligent chitosan hydrogels have drawn great research interest in materials science and engineering. In this paper, we present the recent progress in fabricating intelligent chitosan hydrogels. The features of hydrogels, the advantages of chitosan, and the development of the chitosan intelligent hydrogels are discussed. Diverse physical interactions and chemical covalent bonds have been used to construct the hydrogel network; this review focuses on the interactions that form the hydrogels that are based on chitosan. The stimuli-responsive characteristics, bio-inspired functions and high mechanical strength properties of the chitosan hydrogels are detailed herein. The emphasis of this paper is on the relationship between the structural characteristics and the corresponding functions of the intelligent hydrogels. A perspective on the challenges facing the field and prospects for future development are given.
89 citations
TL;DR: In this paper, NiCo2O4 nanowires grown on Ni foam have been synthesized through a facile hydrothermal approach, revealing a large capacitance and superior cycling stability with 80.3% capacitance retention after 20,000 cycles.
Abstract: The rational design and construction of supercapacitor electrode materials with prominent energy and power density play an indispensable role for their potential application in energy storage devices. In this work, NiCo2O4 nanowires grown on Ni foam have been synthesized through a facile hydrothermal approach, revealing a large capacitance and superior cycling stability with 80.3% capacitance retention after 20 000 cycles. The asymmetric supercapacitors are fabricated based on NiCo2O4 nanowire electrodes, which deliver an energy density of 27.4 W h kg−1 at a power density of 493.2 W kg−1 and an excellent cycle life with 79.2% capacitance retention after 10 000 cycles.
80 citations
TL;DR: In this paper, the ability of these nanoparticles towards the catalytic reduction of 4-nitrophenol with NaBH4 and the dual-catalytic oxidation of formic acid followed by the reduction of methyl orange (MO) was studied.
Abstract: Sodium rhodizonate was used as a bifunctional reducing as well as stabilizing agent for the single step synthesis of gold (Au), silver (Ag), platinum (Pt), and palladium (Pd) nanoparticles (NPs) in water. Transmission electron microscopy analysis revealed that Pt, Au, Ag, and PdNPs have average core diameters of about 2, 8, 26, and 39 nm, respectively. The ability of these nanoparticles towards the catalytic reduction of 4-nitrophenol (4-NP) with sodium borohydride (NaBH4) and the dual-catalytic oxidation of formic acid followed by the reduction of methyl orange (MO) was studied. The apparent rate constants (kapp) of the catalytic reduction of 4-NP in the presence of Ag, Au, Pt, and PdNPs were calculated to be 2.1482, 1.1167, 1.088 × 10−1, and 1.65 × 10−2 min−1, respectively. However, for the dual-catalytic oxidation of formic acid followed by the reduction of MO, the kapp values were calculated to be 4.145, 1.25 × 10−2, 6.7 × 10−3, and 9.0 × 10−5 for the Pt, Pd, Au, and AgNPs, respectively.
TL;DR: In this paper, a new Zn(II) metal-organic framework, formulated as {[Zn(L)]·2.7 DMF} (1), was synthesized using a multidentate ligand 1,4-bis(triazol-1-yl)terephthalic acid (H2L).
Abstract: A new Zn(II) metal–organic framework, formulated as {[Zn(L)]·2.7 DMF} (1), was synthesized using a multidentate ligand 1,4-bis(triazol-1-yl)terephthalic acid (H2L). The MOF 1 adopts 3D uninodal 4-c CdSO4 topology and behaves as a luminescent chemosensor for highly selective and sensitive detection of Fe3+ and nitro-aromatics, particularly 2,4,6-trinitrophenol (TNP). In addition, the thermal stability, UV/Vis diffuse-reflection spectra and photocatalytic behaviors of 1 against organic dyes have also been investigated. The possible mechanism associated with the alleviation in the emission intensity of 1 in the presence of nitro-aromatic compounds were addressed by theoretical calculations. In addition, the photocatalytic activity of 1 against organic dyes was addressed using density of states (DOS) calculations.
TL;DR: In this paper, a colorimetric method was proposed for the detection of H2O2 based on Co3O4-MMT NPs, which can exhibit great potential applications in the medical, food, and environmental fields.
Abstract: Herein, Co3O4 nanoparticles deposited on montmorillonite (Co3O4–MMT NPs) were synthesized via a facile method and characterized by energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), and transmission electron microscopy (TEM). Significantly, the as-prepared Co3O4–MMT NPs were demonstrated to possess an intrinsic peroxidase-like activity, which could rapidly catalytically oxidize the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB·2HCl) by H2O2, accompanied by a visible color change (colorless to blue); these NPs were then used to develop a sensitive colorimetric sensor for the detection of H2O2. The catalytic reaction of Co3O4–MMT NPs followed the Michaelis–Menten kinetics equation, and the composites showed good affinity towards TMB. Via the proposed method, H2O2 can be detected in the range of 10–100 μM with a low detection limit (DL) of 8.7 μM. Fluorescence data reveal that electron transfer among the catalyst, TMB, and H2O2 may contribute to the peroxidase-like activity of the Co3O4–MMT NPs. Finally, a colorimetric method was proposed for the detection of H2O2, and the robustness of the Co3O4–MMT NPs was quite good. The sensor of H2O2 based on Co3O4–MMT NPs can exhibit great potential applications in the medical, food, and environmental fields.
TL;DR: In this paper, the dispersive-micro-solid phase extraction (D-μ-SPE) procedure based on a core-shell magnetic molecularly imprinted polymer (MMIP) in combination with high-performance liquid chromatography-ultraviolet (HPLC-UV) was developed for the preconcentration and determination of quercetin residues in Apium graveolens, Brassica oleracea, Spinacia olderacea, watercress, onion, and apple matrices.
Abstract: The objective of this study was to develop a simple, sensitive and selective procedure for the preconcentration and determination of quercetin residues in Apium graveolens, Brassica oleracea, Spinacia oleracea, watercress, onion, and apple matrices This novel method was developed on the basis of the dispersive-micro-solid phase extraction (D-μ-SPE) procedure based on a core–shell magnetic molecularly imprinted polymer (MMIP) in combination with high-performance liquid chromatography-ultraviolet (HPLC-UV) Variables affecting the quercetin extraction efficiency included pH, MIP dose, extraction contact time, elution organic solvent, and volume of organic solvent and were evaluated by the experimental central composite design (CCD) The obtained optimal parameters were as follows: pH (35), sorbent (12 mg), elution organic solvent and solvent volume (methanol, 02 mL), and elution time (220 min, without adding salt) The calibration curve was linear in the concentration range of 06–5500 μg L−1 with the lower limits of detection found in the range of 0113–0117 μg L−1, thereby revealing the high-sensitivity and -selectivity properties The combination of D-μ-SPE and HPLC-UV could provide a method for the recovery of the analyte in various matrices at 22 min contact time with good reusability and excellent recoveries at four concentration levels (50, 100, 500, and 1000 μg L−1), ranging between 9544 and 10689% (relative standard deviation <60%) Based on competitive sorption experiments, the synthesized MMIP displays higher selectivity toward quercetin compared to non-imprinted polymers (NIPs) and other sorbents
TL;DR: In this paper, the synthesis of TiO2 quantum dots, carbon dots (C-dots), and TiO 2/C-Dots using facile sol-gel and hydrothermal methods was reported.
Abstract: This paper reports the synthesis of TiO2 quantum dots, carbon dots (C-dots), and TiO2/C-dots using facile sol–gel and hydrothermal methods. The synthesized quantum dots were further characterized in detail to understand their crystalline, structural, morphological, thermal and optical properties using various spectroscopic and analytical techniques. The characterization results confirmed that the prepared photocatalysts exhibited high crystallinity, purity and excellent optical properties. The morphological results indicated that the C-dots were uniformly distributed over the TiO2 quantum dots and nanocomposites have an average size of 12 nm. Furthermore, the prepared sample, i.e. TiO2/C-dots, was efficiently employed as a potential heterogeneous photocatalyst for solar light driven photocatalytic degradation of a fluoroquinolone antibiotic drug levofloxacin. To optimize the photocatalytic degradation experiments, various catalyst dose-dependent, pH-dependent, and initial drug-concentration dependent experiments were carried out. The photocatalytic experiments revealed almost complete photocatalytic degradation of levofloxacin (10 mg L−1) within 90 minutes of solar light illumination using the TiO2/C-dots under optimum conditions, whereas bare TiO2 showed only 66.5% degradation of the drug. Different commercial photocatalysts such as TiO2 PC-50 and TiO2 PC-500 were also used for comparing the photocatalytic efficiency of the synthesized photocatalyst. Furthermore, the stability of the photocatalyst was studied by performing recyclability experiments up to 5 cycles using the TiO2/C-dots, indicating that the nanocomposites could be reused without any significant loss. The TOC results indicated the simultaneous 53.4% mineralization and photocatalytic degradation of levofloxacin under optimized conditions. The enhanced photocatalytic activity of the nanocomposites was attributed to the presence of the C-dots in the system, which provided more active sites for the drug molecules and also restricted the recombination of charge carriers. The role of active radical species in the photocatalytic degradation of levofloxacin was also investigated. A photocatalytic degradation mechanism and pathway were also proposed.
TL;DR: In this paper, a sulfonated polyethylene glycol-coated Fe3O4 nanocomposite was used for selective oxidation of sulfides to sulfoxides or sulfones with brilliant yields under solvent free conditions by employing 30% hydrogen peroxide as the oxidant.
Abstract: We present below a sulfonated-polyethylene glycol-coated Fe3O4 nanocomposite (Fe3O4/PEG-SO3H) as a greatly effective and ecological nanocatalyst for the selective oxidation of sulfides to sulfoxides or sulfones with brilliant yields under solvent-free conditions by employing 30% hydrogen peroxide as the oxidant. A number of sulfides containing alcohol, ester, and aldehyde functional groups were fruitfully and selectively oxidized without altering the desired characteristics. The magnetic nanocatalyst (Fe3O4/PEG-SO3H) can be conveniently and swiftly retrieved through the utilization of an external magnetic tool and recycled for more than 10 reaction runs without significantly decreasing its catalytic behavior.
TL;DR: In this article, the photocatalytic properties of boron nitride (BN) nanosheets and silver (Ag) composite nanofibers were investigated for organic compound degradation and bacterial removal.
Abstract: To develop material with good photocatalytic properties for organic compound degradation and bacterial removal, we produced Ag/TiO2 and BN–Ag/TiO2 composite nanofibers that included controlled amounts of boron nitride (BN) nanosheets and silver (Ag). After annealing at 500 °C under air, we used scanning electron microscopy, transmission electron microscopy, Brunauer–Emmet–Teller analysis, X-ray diffraction, energy-dispersive X-ray spectroscopy, Raman spectroscopy, UV-visible reflectance spectroscopy and room temperature photoluminescence to investigate the morphological, structural and optical properties of all samples. The photocatalytic tests using methylene blue under visible light, in repeated and long-term applications, showed that the photodegradation activity of BN(5 wt%)–Ag(3 wt%)/TiO2 composite nanofibers was 17.2 and 2.3 times higher than that of pure TiO2 and Ag(3 wt%)/TiO2 nanofibers, respectively. In antibacterial tests using Gram-negative Escherichia coli, 3 hours of incubation with BN(5 wt%)–Ag(3 wt%)/TiO2 composite nanofibers killed all bacteria. These results indicate that the synthesized BN(5 wt%)–Ag(3 wt%)/TiO2 composite nanofibers can be considered to be a multifunctional material for photodegradation and antibacterial applications.
TL;DR: In this paper, the authors demonstrate very good carbon monoxide (CO) sensing capability of bismuth ferrite (BFO) nanoparticles prepared through a simple sol-gel technique.
Abstract: Creation of novel functionality in materials is always fascinating for researchers/scientists. Bismuth ferrite (BFO), a well known multiferroics material with simultaneous magnetic and electric order, is promising for spintronics and memory devices. Herein, we were able to demonstrate for the first time very good carbon monoxide (CO) sensing capability of bismuth ferrite (BFO) nanoparticles prepared through a simple sol–gel technique. Morphological/structural characterization was performed using various standard sophisticated modern probes, which confirms the formation of single phase BFO nanoparticles. The sensing properties of BFO nanoparticles towards CO was tested for concentrations in the range of 5 ppm–30 ppm at different temperatures (between 270 °C to 450 °C). Very good response (Rg/Ra) of around 2.12 towards 30 ppm CO at an operating temperature of 350 °C was observed. The as-prepared sensors exhibited rapid response and recovery time of around 25 s and 13 s, respectively, for sensing 30 ppm CO. In addition, the sensors are selective, highly reproducible and remain quite stable for almost 150 days, which is required for device application. A plausible mechanism has been proposed to explain the CO sensing behaviour of the BFO nanoparticles. On the basis of the observed sensing properties we believe that a BFO nanoparticle-based sensor could be a suitable alternative to conventional oxide-based sensors having various difficulties.
Abstract: Zinc oxide nanoparticles (ZnONPs) have received considerable attention as an antibacterial agent particularly in the textile industry. In the present work a successful procedure for in situ growth of ZnONPs in textiles was developed. The results obtained showed that a combination of in situ synthesis and the sol–gel method promoted a uniform and dense adsorption of the nanoparticles both inside and on the surface of fabric fibres. The fabrics finished with ZnONPs have been investigated for antibacterial properties by the agar diffusion method and by the absorption method according to the ISO 20743:2013 standard and exhibited an antibacterial effect against methicillin resistant Staphylococcus aureus ATCC33591, Staphylococcus epidermidis ATCC1228, Staphylococcus aureus RN4220 and Propionibacterium acnes ATCC6919. Moreover, tests conducted with hydrogen peroxide suggested the involvement of reactive oxygen species, namely the involvement of hydrogen peroxide, in the antibacterial activity of the zinc oxide nanoparticles. Therefore, the synthesised nanoparticles showed great potential to be used as coatings for medical, cosmetic or sports fabrics.
TL;DR: In this paper, a dual-emitting carbon dot/silicon dot conjugates were used to detect ciprofloxacin (CIP) in solution phase and filter paper.
Abstract: Herein, we report a novel and facile strategy for the ratiometric fluorescence (FL), solution-phase and filter-paper visual detection of ciprofloxacin (CIP) based on dual-emitting carbon dot/silicon dot (CD/SiD) conjugates. Red-emissive CDs with surface amino-modification were combined with surface carboxyl-modified and blue-emissive SiDs via carbodiimide-activated coupling. Then, the conjugates were functionalized with bis(3-pyridylmethyl)amine (BPMA) on the SiD surface to prepare CDs/SiDs–BPMA hybrids. The coordination of Cu2+ to BPMA sites led to marked blue FL quenching of SiDs because of photo-induced electron transfer from SiDs to the BPMA–Cu2+ complex. The addition of CIP induced clear FL recovery of SiDs due to competitive coordination of Cu2+ to CIP over BPMA. The Cu2+ ions specifically reacted with BPMA and CIP on the SiD surface but hardly influenced the red FL of CDs, which thus served as a reference. The CDs/SiDs–BPMA–Cu2+ system was developed as an efficient ratiometric FL (ISiDs/ICDs) probe to determine CIP based on CIP-induced dramatic ratiometric FL turn-on responses and FL color changes from red to blue. This probe enabled naked-eye visual detection of CIP in the solution phase and on filter paper. In pharmaceutical preparations and real human fluids, this probe exhibited superior capability for CIP detection over interferents with high detection recoveries.
TL;DR: In this article, a facile hydrothermal technique was applied to prepare doped Fe2O3/CeO2 nanocubes (NCs) in alkaline medium at low temperature.
Abstract: A facile hydrothermal technique was applied to prepare doped Fe2O3/CeO2 nanocubes (NCs) in alkaline medium at low temperature. The calcined NCs were characterized by Fourier-transform infrared spectroscopy (FTIR), ultraviolet visible spectroscopy (UV/vis), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), and powder X-ray diffraction (XRD). A chemical sensor was fabricated with a glassy carbon electrode (GCE) modified by deposition of a uniform thin layer of NCs film. The fabricated chemical sensor was used successfully to detect hydrazine selectively by a reliable electrochemical method at lower potential. The sensor's analytical performances, including good sensitivity (0.1275 μA μM−1 cm−2), low detection limit (7.45 ± 0.37 pM), broad linear dynamic range (0.02 μM–0.02 M), precious reproducibility, low limit of quantification (0.22 ± 0.01 μM) and long-term stability, were investigated. An efficient hydrazine chemical sensor based on Fe2O3/CeO2 NCs/binder/GCE was developed and performed well in terms of analytical sensing performances as well as being validated for environmental and extracted real samples.
TL;DR: The asymmetric supercapacitor (ASC) device is denoted as Nd(OH)3/G‖AC; a poly(vinylidene fluoride) electrospun membrane soaked in 6 M KOH was used as a separator as well as the electrolyte as discussed by the authors.
Abstract: Neodymium hydroxide nanorods [Nd(OH)3] are developed by a facile chemical precipitation method without any surfactants/templates at ambient temperature. The neodymium hydroxide nanorods–graphene [Nd(OH)3/G] nanohybrid is prepared by a simple solvothermal reduction process using Nd(OH)3/GO in a mass ratio of 1 : 0.5 in dimethylformamide for 7 h. This new Nd(OH)3/G nanohybrid can be used as an electrode material for supercapacitors; it exhibits good capacitive behaviour, with a specific capacitance of 820 F g−1 at 1 A g−1. The nanohybrid exhibits a capacitance retention of 96% even after 3000 continuous charge–discharge cycles. This excellent electrochemical behaviour is mainly attributed to the synergetic effect of Nd(OH)3 and graphene. The asymmetric supercapacitor (ASC) device is denoted as Nd(OH)3/G‖AC; a poly(vinylidene fluoride) electrospun membrane soaked in 6 M KOH was used as a separator as well as the electrolyte. The ASC device functions in an optimized potential window of 1.6 V with an energy density of 40 W h kg-1. Furthermore, the ASC device exhibits excellent capacitance retention of 85.3% with a Coulombic efficiency of 97% even after 5000 cycles. This new hybrid electrode material shows impressive performance and can be used as an electrode material for asymmetric supercapacitors.
TL;DR: In this paper, a novel cardanol based benzoxazine was synthesised by reacting three different amines (aniline, N,N-dimethylaminopropylamine (CrDb) with cardanol in the presence of formaldehyde under appropriate experimental conditions.
Abstract: In the present work, a novel cardanol based benzoxazine was synthesised by reacting three different amines (aniline (CrAb), N,N-dimethylaminopropylamine (CrDb) and caprolactam modified N,N-dimethylaminopropylamine (CrCb)) with cardanol in the presence of formaldehyde under appropriate experimental conditions. The resulting benzoxazines were characterised for their molecular structure and thermal behaviour using different analytical methods. Among the different systems studied, the tertiary amine derivatives were found to reduce the curing temperature efficiently (CrAb-275 °C > CrDb-265 °C > CrCb-251 °C) and were confirmed by DSC analysis. These cardanol based CrAb benzoxazines were blended with conventional benzoxazines (Bzs) and bismaleimides (BMIs) as binary and ternary systems and their thermal properties were studied. Three different catalysts (4-hydroxy acetophenone, 4-aminophenol, and 4-hydroxyphenyl maleimide) were used to study the effect of lowering the curing temperature. Further, the prepared benzoxazines were reinforced with varying weight percentages (1, 3, 5 and 10 wt%) of bio-silica derived from rice husk to obtain hybrid composites. The dielectric studies of bio-silica reinforced cardanol benzoxazines infer that the values of dielectric constant decreased with increasing wt% of bio-silica. It was further observed that 10 wt% bio-silica reinforced cardanol benzoxazines show the lowest value of dielectric constant of 1.9 at 1 MHz. From the data obtained from the different studies, it is concluded that the blends of cardanol based benzoxazines can be used in the form of sealants, encapsulants, adhesives and matrices in the fields of microelectronics and automobile applications for better performance.
TL;DR: In this paper, a one-step procedure for the fabrication of Pd-Ag bimetallic nanoparticles on the surface of a graphene oxide (rGO) support was reported.
Abstract: In this study we report a one-step procedure for the fabrication of Pd–Ag bimetallic nanoparticles on the surface of a graphene oxide (rGO) support. A controlled reduction of Pd2+ and Ag+ ions on an rGO support was achieved by using a methyl ammonium borane reducing agent. The fabricated Pd–Ag/rGO bimetallic nanocomposites were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FT-IR). A Pd–Ag/rGO based electrochemical sensor was fabricated by immobilizing the as-prepared Pd–Ag/rGO bimetallic nanocomposites on to a bare glassy carbon electrode (GCE). The resulting Pd–Ag/rGO/GCE electrochemical sensor was proved to be ultrasensitive and selective towards the detection of acetaminophen (APAP) in the presence of etilefrine (ET). The linear dynamic range (LDR) for the detection of APAP was found to be 1.2–30 nM with a good limit of detection (LOD) and the limit of quantification (LOQ) of 3.26 nM and 13 nM, respectively. The newly prepared Pd–Ag/rGO/GCE-modified electrode makes a good analytical tool for the accurate determination of APAP either in its pristine conditions or in the presence of both real human samples and pharmaceutical formulations. The convenient fabrication protocol shown here can be extendable to other types of bimetallic configurations for various electrochemical sensing applications.
TL;DR: In this paper, an equimolar one-pot reaction of PbX2 (X = NO3−, CH3COO−) salts with HLI and H2LII in MeOH at 60 °C in a branched tube apparatus leads to heteroleptic complexes.
Abstract: The evaluation of N′-(pyridin-2-ylmethylene)nicotinohydrazide (HLI) and N,N′′′-bis(1-(pyridin-2-yl)-ethylidene)carbazide (H2LII) as linker precursors in the synthesis of novel PbII extended structures is described. An equimolar one-pot reaction of PbX2 (X = NO3−, CH3COO−) salts with HLI and H2LII in MeOH at 60 °C in a branched tube apparatus leads to heteroleptic complexes [Pb(HLI)(NO3)2]n (1), [Pb(LI)(CH3O)]n (2), [Pb2(H2LII)(NO3)4] (3) and [Pb2(HLII)(CH3COO)3]n (4), respectively. The nature of the anion in the parent PbII salt also influences the final structure. In all complexes, the PbII center exhibits a hemidirected coordination geometry with all the covalent bonds being concentrated on one hemisphere of the coordination sphere. The sterically available PbII ion participates in Pb⋯O/N tetrel bonding or Pb⋯Cg interaction as evidenced from the detailed structural and topological analysis of the described complexes. As a result of these interactions, the structures of all four compounds can be extended to a higher dimensional framework, which is further stabilized by hydrogen N–H⋯O/C–H⋯O and dihydrogen C–H⋯H–C bonds and/or π⋯π stacking interactions. The complementary Hirshfeld surface analysis of the discrete complex 3, considering covalent bonds, showed that the structure is highly dominated by H⋯X (X = O, H and C) and O⋯Y (Y = O, Pb, C and N) contacts, of which the O⋯Pb/H/N/C contacts are highly favoured. DFT based charge and energy decomposition (ETS-NOCV) calculations are performed in order to shed light on the nature of the non-covalent interactions that determine the stability of the obtained structures.
TL;DR: In this paper, a microporous sulfur-doped carbon microspheres (S-MCMS-900) was synthesized and assembled as an electrochemical sensor for the monitoring of ascorbic acid (AA) in commercial juices and vitamin C tablets.
Abstract: Fabrication of electrodes based on a metal-free catalyst with desirable sensitivity, selectivity, and stability has been given considerable interest. Microporous sulfur-doped carbon microspheres (S-MCMS) were synthesized and assembled as an electrochemical sensor for the monitoring of ascorbic acid (AA) in commercial juices and vitamin C tablets. The S-doped microporous carbon with a spherical structure was fabricated at different annealing temperatures (700, 800, and 900 °C) to achieve a high surface area, an actively doped carbon interfacial surface, soft interactive surfaces and an open microporous network. The high surface area, actively doped S-atom percentage, microporous construction, and active doping of the carbon microsphere construction of S-MCMS-900, make it a highly stable metal-free electrocatalyst for selective detection of AA. The S-atoms incorporated with the sp2-carbon matrix form numerous active sites, which bind to targets and stimulate the transduction of the electrochemical interaction with a fast response and high charge transfer efficiency. Selective monitoring of AA on S-MCMS-900 with high sensitivity was achieved with a detection limit as low as 1 μM, and wide linear range up to 4 mM. Monitoring of AA in lemon juice or pharmaceutical tablets was realized by using S-MCMS-900, with a fast response, high sensitivity, reliable selectivity, high stability and rational reproducibility. S-MCMS-900 can be employed as a fast, sensitive, and selective assay for routine detection of AA in food, biological, and environmental samples.
TL;DR: In this paper, the features of non-covalent hole interactions of the halogen, chalcogen and pnictogen bond families were discussed by means of molecular orbital theory and the analysis of charge transfer and electrostatic forces.
Abstract: By means of molecular orbital theory and the analysis of charge transfer and electrostatic forces, we discuss the features of non-covalent hole interactions of the halogen, chalcogen and pnictogen bond families. The use of MOs allows us to explain and predict the location of holes, and to design novel interactions such as systems with σ and π holes on the same or opposite sides. In view of the orbital origin of the hole interactions, we suggest that many chalcogen and pnictogen bonds are largely based on π holes and not on the commonly accepted σ holes. In addition, a new type of hole interaction based on δ holes is found on the sextuply bonded dimolybdenum.
TL;DR: In this article, a carbon paste electrode, modified with 1-butylpyridinium hexafluorophosphate and CuO nanoparticles (CPE/1-BPr/CuO-NPs), was used as an amplified sensor for the electrochemical determination of Epirubicin (EB) and topotecan (TP).
Abstract: Epirubicin (EB) and topotecan (TP) are two major anticancer drugs that are used in breast cancer therapy with many side effects In this research, we introduce a carbon paste electrode, modified with 1-butylpyridinium hexafluorophosphate and CuO nanoparticles (CPE/1-BPr/CuO-NPs), as an amplified sensor for the electrochemical determination of EB The electrochemical behavior of EB was initially studied on the surface of CPE/1-BPr/CuO-NPs, CPE/CuO-NPs, CPE/1-BPr, and on bare carbon paste electrodes The CPE/1-BPr/CuO-NPs showed two separate oxidation signals with a potential of 628 mV and 935 mV in the oxidation of EB and TP, respectively; these potentials are sufficient for determining them simultaneously The linear response range was found to be 003 to 800 μM (R2 = 09972) and 07 to 800 μM (R2 = 09984) for the EB and TP concentrations, with limits of detection (LODs) of 0008 μM and 03 μM, respectively Finally, the concentrations of EB and TP were successfully measured by CPE/1-BPr/CuO-NPs as a voltammetric sensor in real samples
TL;DR: In this article, X-ray diffraction, Raman and Fourier transform infra-red spectroscopies confirmed the presence of Co3O4/CoO in the carbon matrix.
Abstract: Cobalt oxide (Co3O4/CoO) nanoparticle-embedded carbon matrix (Co3O4/CoO@carbon) was synthesized by pyrolysis of cobalt-salen complex ([Co(salen)]) followed by hydrothermal treatment. The X-ray diffraction, Raman and Fourier transform infra-red spectroscopies confirmed the presence of Co3O4/CoO in the carbon matrix. The scanning electron microscopy observation showed highly agglomerated spike-like grains. The TEM observation confirmed that the Co3O4/CoO grains were embedded in the carbon matrix. The supercapacitor studies conducted on the Co3O4/CoO@carbon matrix revealed a specific capacity of 324 C g−1 at 1 A g−1 in 1 M KOH. The Co3O4/CoO@carbon electrode also exhibited long-term life cycle with a high Coulombic efficiency of 96%. It is believed that the carbon present in Co3O4/CoO acted as a conductive nano-network, leading to such a high supercapacitor performance. The Co3O4/CoO@carbon material was also tested for its catalytic property, and it was found that the prepared material exhibited excellent photocatalytic degradation of azure A dye.
TL;DR: In this paper, highly luminescent N-doped carbon dots (CG-CDs) obtained from citric acid and glycine with a quantum yield of 78% and label-free fluorescent assay system were designed for Cr(VI) detection based on the inner filter effect (IFE).
Abstract: Chromium is highly toxic and considered as a severe contaminate. Therefore, low cost, highly sensitive sensors for the determination of Cr(VI) are highly required. In the present study, highly luminescent N-doped carbon dots (CG-CDs) obtained from citric acid and glycine with a quantum yield of 78% and label-free fluorescent assay system were designed for Cr(VI) detection based on the inner filter effect (IFE). The CG-CDs were prepared by a one-step hydrothermal method using citric acid and glycine as carbon precursors. The fluorescent sensors showed rapid response, high selectivity, and sensitivity to Cr(VI). A good linear relationship between the concentration of Cr(VI) ions and fluorescence intensity was obtained in the range from 5 to 200 μmol L−1 (R2 = 0.98), and the limit of detection was calculated to be 4.16 μmol L−1 for Cr(VI). Importantly, this method has been successfully applied to the detection of Cr(VI) ions in simulated aquaculture water, which may be helpful to reduce the risk of Cr(VI) intake from contaminated water.