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1.
Langmuir ; 40(11): 5785-5798, 2024 Mar 19.
Article in English | MEDLINE | ID: mdl-38446077

ABSTRACT

In the modern era, water pollution, especially from industries, agricultural farms, and residential areas, is caused by the release of a large scale of heavy metals, organic pollutants, chemicals, etc., into the environment, posing a serious threat to aquatic ecosystems and nature. Moreover, untreated sewage waste discharged directly into nearby water bodies can cause various diseases to mankind due to the high load of fecal coliform bacteria. This work demonstrates the development of a biocompatible, cost-effective, highly robust, efficient, flexible, freestanding, and reusable membrane using naturally formed biocompatible kaolinite clay-doped poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) for effective piezodynamic destruction of coliform bacteria. In this study, Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) have been used to evaluate the mechanical stimulus-responsive antibacterial efficacy of the nanocomposite membrane. The membrane can effectively eradicate nearly 99% viable E. coli and 97% E. faecalis within a span of 40 min under mechanical stimulation (soft ultrasound ∼15 kHz). To further understand the mechanism, an evaluation of reactive oxygen species and bacterial FESEM was performed. These studies revealed that bacterial cells suffered severe visible cell damage after 40 min of piezocatalysis, elucidating the fact that the synthesized membrane is capable of producing a superior piezodynamic antibacterial effect.


Subject(s)
Escherichia coli , Wastewater , Clay , Ecosystem , Anti-Bacterial Agents/pharmacology , Bacteria
2.
J Environ Manage ; 359: 120985, 2024 May.
Article in English | MEDLINE | ID: mdl-38677226

ABSTRACT

Amid rising water contamination from industrial sources, tackling toxic dyes and pathogens is critical. Photocatalysis offers a cost-effective and eco-friendly solution to this pressing challenges. Herein, we synthesized Te4+ and Er3+ doped ZrO2 photocatalysts through hydrothermal method and investigated their efficacy in degrading Congo red (CR) and pathogens under visible light. XRD and Raman Spectroscopy confirm monoclinic and tetragonal mixed-phases without any impurities. Doping-induced defects, reduced crystalline diameter, high surface area, modified bandgap (2.95 eV), photoluminescence quenching, coupled with interfacial polarization, contribute to EZO's excellent dielectric response (1.149 × 106), for achieving remarkable photocatalytic activity, verified by photoelectrochemical measurements, LC-MS and phytotoxicity analysis. Under optimal conditions, EZO achieves 99% CR degradation within 100 min (TOC 79.9%), surpassing ZO (77%) and TZO (84%). Catalyst dosages, dye concentrations, and solution pH effect on EZO's photocatalytic performance are systematically assessed. Scavenging experiment emphasized the pivotal role of · OH in CR degradation with 96.4% efficiency after 4 cycles, affirming its remarkable stability. Moreover, EZO demonstrates ROS-mediated antibacterial activity against E. faecalis and E. coli bacteria under visible light, achieving >97% and >94% inhibition rate with an inhibition zone > 3 mm. Hence, the nanoparticle's dual action offers a practical solution for treating contaminated wastewater, ensuring safe irrigation.


Subject(s)
Anti-Bacterial Agents , Zirconium , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Catalysis , Zirconium/chemistry , Nanoparticles/chemistry , Erbium/chemistry , Congo Red/chemistry
3.
J Fluoresc ; 32(4): 1489-1500, 2022 Jul.
Article in English | MEDLINE | ID: mdl-35503196

ABSTRACT

This article reports the fluorometric detection of toxic hexavalent chromium Cr (VI)) in wastewater and Cr (VI) contaminated living cells using in-situ grown carbon quantum dots into the goethite (α-FeOOH) nano-matrix. The synthesized nano-hybrid shows enormous potential in determining the chromium contamination levels in various types of water samples. This selective fluorometric probe is enormously sensitive (LOD 81 nM) toward hexavalent chromium, which makes it a dedicated chromium sensor. Moreover, the sensing mechanism has been assessed using Stern-Volmer's equation and fluorescence lifetime experiments showing the simultaneous occurrence of photoinduced electron transfer and the inner filter effect. This chromium sensor has also been employed to assess the contamination level in real-life industrial wastewater. The performance of this probe in a real-life wastewater sample is quite commendable. Further, this biocompatible fluorometric probe has been used to demonstrate the in-vitro sensing of Cr (VI) in HeLa cells. The rapid detection mechanism of hexavalent chromium in living cells has been validated using theoretical docking simulations. Henceforth, this fluorometric sensor material could open new avenues not only in wastewater monitoring but also in biomedical applications.


Subject(s)
Wastewater , Water Pollutants, Chemical , Carbon , Chromium/analysis , HeLa Cells , Humans , Iron Compounds , Minerals , Water Pollutants, Chemical/analysis
4.
Biometals ; 35(3): 499-517, 2022 06.
Article in English | MEDLINE | ID: mdl-35355153

ABSTRACT

A family of dioxidovanadium(V) complexes (1-4) of the type [Na(H2O)x]+[VVO2(HL1-4)]- (x = 4, 4.5 and 7) where HL2- represents the dianionic form of 2-hydroxybenzoylhydrazone of 2-hydroxyacetophenone (H2L1, complex 1), 2-hydroxy-5-methylacetophenone (H2L2, complex 2), 2-hydroxy-5-methoxyacetophenone (H2L3, complex 3) and 2-hydroxy-5-chloroacetophenone (H2L4, complex 4), have been synthesized and characterized by analytical and spectral methods. These complexes exhibited the potential abilities to suppress the erythrocytes carbonic anhydrase enzymatic activity in type 1 and type 2 diabetic patients (in vitro), promising antidiabetic activity against T2 diabetic mice (in vivo). They also exhibited significant cytotoxic activity against cervical cancer (SiHa) cells (in vitro) as the IC50 value of complexes 1, 2 and 4 is substantially lower than the value found for cisplatin while that of 3 is comparable and follow the order: 4 < 1 < 2 < 3 and can kill the cells by apoptosis via the generation of reactive oxygen species (ROS). The complexes are soluble both in water and octanol media and also non-toxic at working concentrations. The antidiabetic activity of these four complexes follows the order: 4 > 2 > 1 > 3 while both the carbonic anhydrase and cytotoxic activity follow the order: 4 > 1 > 2 > 3 suggesting that complex 4, containing electron withdrawing Cl atom is the most reactive while 3 with electron donating OCH3 group is the least reactive species. The molecular docking study on hCA-I and hCA-II demonstrates that complexes interact via hydrogen bonding as well as different types of π-stacking.


Subject(s)
Antineoplastic Agents , Carbonic Anhydrases , Diabetes Mellitus, Experimental , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Carbonic Anhydrase Inhibitors/chemistry , Carbonic Anhydrase Inhibitors/pharmacology , Carbonic Anhydrases/metabolism , Diabetes Mellitus, Experimental/drug therapy , Humans , Hydrazones/chemistry , Hydrazones/pharmacology , Hypoglycemic Agents/pharmacology , Mice , Molecular Docking Simulation , Structure-Activity Relationship
5.
Mikrochim Acta ; 188(4): 134, 2021 03 23.
Article in English | MEDLINE | ID: mdl-33759061

ABSTRACT

A flexible nano-engineered natural mineral (carbon dot doped natural microcline) based membrane (MCPV) has been developed, which can efficiently detect the presence of hexavalent chromium (Cr6+) and trivalent iron (Fe3+) ions in water by altering its fluorescence emission. Detailed characterization of the membrane was carried out using XRD, FT-IR spectroscopy, FESEM, TEM, and UV-Vis spectroscopy. Mechanical and temperature stabilities were also investigated. This new-generation sensor membrane is designed in such a way that it does not dissolve in water, keeping the water quality unaffected. The fluorescence studies were conducted at 414 nm and "turn-off" response was observed specifically for Fe3+ at 489 nm. A prominent red shift (530 nm) of the fluorescence maxima takes place when it comes to Cr6+. Figures of merit, such as LOD (8.7 µM for Cr6+ and 18.4 µM for Fe3+) and LOQ (29.1 µM for Cr6+ and 61.6 µM for Fe3+), were evaluated from the linear range (0-60 µM for Cr6+ and 0-30 µM for Fe3+) of the calibration curve (Stern-Volmer plots) showing high sensitivity of this sensing probe toward Cr6+ and Fe3+. Recovery and RSD calculations were done in various real-life water samples on intraday-interday basis to determine the accuracy of the sensor. This work validates the fact that the synthesized sensor membrane is capable of detecting these heavy metals in glutathione environment as well, which could be beneficial for early-stage carcinogen detection in living cells.


Subject(s)
Aluminum Compounds/chemistry , Carcinogens/analysis , Chromium/analysis , Iron/analysis , Membranes, Artificial , Quantum Dots/chemistry , Silicates/chemistry , Carbon/chemistry , Density Functional Theory , Drinking Water/analysis , Fluorescent Dyes/chemistry , Glutathione/chemistry , Limit of Detection , Models, Chemical , Molecular Docking Simulation , Ponds/analysis , Spectrometry, Fluorescence/methods , Wastewater/analysis , Water Pollutants, Chemical/analysis
6.
Physiol Mol Biol Plants ; 26(8): 1685-1693, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32801496

ABSTRACT

During a survey performed in sapota orchards of India, from 2015 to 2018, symptoms of phyllody, little leaf, flat stem and witches' broom were observed in three states: Karnataka, Kerala and Tripura. The association of phytoplasmas was confirmed in all the symptomatic sapota samples by using nested PCR specific primers (P1/P7, R16F2n/R16R2 and 3Far/3Rev) with amplification of fragments of ~ 1.25 kb and ~ 1.3 kb. Association of three phytoplasma groups, aster yellows with flat stem from Tripura (Lembucherra), clover proliferation with phyllody symptoms at Karnataka (Bengaluru) and bermuda grass white leaf with flat stem and little leaf from Kerala (Thiruvananthapuram) and Tripura (Cocotilla) were confirmed by 16S rRNA gene sequence comparison analysis. Virtual RFLP analysis of 16S rRNA gene sequences using pDRAW32 further classified the sapota phytoplasma isolates into 16SrI-B, 16SrVI-D and 16SrXIV-A subgroups. This is the first report on identification of three phytoplasma groups in sapota in world.

7.
Langmuir ; 35(52): 17016-17026, 2019 Dec 31.
Article in English | MEDLINE | ID: mdl-31815478

ABSTRACT

Herein, biocompatible Ca3(PO4)2 nanorod-incorporated poly(vinylidene) difluoride films have been prepared via an in situ process. A good piezoelectricity (d33 ≈ 56.6 pC/N) along with a large dielectric constant of ∼3.48 × 105 at frequency 20 Hz has been achieved. Then, we have designed a biocompatible, highly durable, low-cost piezoelectric nanogenerator (CPNG) which shows the superiority in open-circuit voltage ∼47 V and current ∼1.8 µA generation with power density ∼47.4 mW cm-3 under the gentle touch of a finger. Excellent mechanical to electrical energy conversion efficiency (∼65.5%) of our developed CPNG leads to fast charging of a capacitor of 1 µF in 18 s and glowing of 26 light-emitting diodes (LEDs) under finger impartation. Further, a portable light-charging power pack (LCPP) has been developed using the high dielectric film as the storage function. Under light illumination, our LCPP generates open-circuit output voltage ∼1.29 V with short-circuit current 5.7 mA cm-2. Areal capacitance ∼1779 F m-2 and storage efficiency ∼88% are achieved. The device is able to lighten up 22 LEDs for 10 days after charging once.

8.
Langmuir ; 35(19): 6346-6355, 2019 May 14.
Article in English | MEDLINE | ID: mdl-30998847

ABSTRACT

In the present work, we propose a simple and unique approach to design a lightweight, low-cost, self-charging power cell with considerable capacity to generate and store photocharges named self-charged photo-power cell (SCPPC). Initially, highly electroactive sodium dodecyl sulfate (SDS)-incorporated poly(vinylidene fluoride) (PVDF) composite thin films with a large dielectric constant of ∼525 are synthesized via a simplistic solution casting process. Then, the as-prepared high-dielectric SDS/PVDF thin film is used as a charge-storage medium in combination with an inorganic-organic dye film, i.e., ZnO nanoparticles-eosin Y-poly(vinylpyrrolidone) film, as a photoelectron generator in our SCPPC. An open-circuit voltage of ∼1.2 V is attained after charging SCPPC under illumination light with intensity ∼110 mW/cm2 and then discharging fully with a constant current density of ∼4.5 mA/cm2. A specific areal capacitance of ∼450 F/m2 is obtained with large energy and power densities of ∼90 mWh/m2 and 54 W/m2, respectively. The improved overall efficiency, ∼3.78%, along with 89% storage efficiency leads to promising application possibilities of our rechargeable photo-power cell. The recyclability, i.e., rechargeability and storage durability, of the photo-power cell are also checked for 35 days without no such reduction in voltage generation and storage. Also, multicolored light-emitting diodes are lightened up using the photo-power cell as power source.

9.
Inorg Chem ; 58(13): 8369-8378, 2019 Jul 01.
Article in English | MEDLINE | ID: mdl-31247863

ABSTRACT

This article reports the effect of Gd(III) doping on the structure, microstructure, and optical properties of boehmite nanoparticles. The bright-blue fluorescence along with a long lifetime makes our material an efficient candidate for optical applications. Our material particularly targets and eliminates hexavalent chromium ions (Cr(VI)) from aqueous media, which turns it into a multifunctional fluorescent nanosensor (MFNS). The development of an efficient hexavalent chromium ion (Cr(VI)) sensor to detect and quantify Cr(VI) ions is still a serious issue worldwide. Thus, this work will be very beneficial for various environmental applications. No such work has been reported so far which includes cost-effective and biocompatible boehmite nanoparticles in this field. Detailed synthesis and characterization procedures for the MFNS have been incorporated here. The biocompatibility of the MFNS has also been studied rigorously by performing cell survivability assay (MTT) and cellular morphology assessments. Our extensive research confirmed that the "turn-off" sensing mechanism of this sensor material is based on a collisional quenching model which initiates the photoinduced electron transfer (PET) process. High selectivity and sensitivity (∼1.05 × 10-5 M) of the MFNS toward hexavalent chromium ions even in real life wastewater samples have been confirmed, which makes this fluorescent probe a potential candidate for new age imaging and sensing technologies.


Subject(s)
Aluminum Hydroxide/chemistry , Aluminum Oxide/chemistry , Chromium/analysis , Fluorescent Dyes/chemistry , Nanoparticles/chemistry , Wastewater/analysis , Adsorption , Aluminum Hydroxide/chemical synthesis , Aluminum Oxide/chemical synthesis , Cell Line, Tumor , Fluorescence , Fluorescent Dyes/chemical synthesis , Gadolinium/chemistry , Humans , Limit of Detection , Microscopy, Fluorescence/methods , Porosity , Spectrometry, Fluorescence/methods
10.
Appl Opt ; 58(33): 9163-9171, 2019 Nov 20.
Article in English | MEDLINE | ID: mdl-31873592

ABSTRACT

Recently, titanium-based nanostructures with high nonlinear optical properties have found use in ultrafast photonic system applications. Here, we report a study of the third-order nonlinear optical property of the ${{\rm CuCo}_{0.5}}{{\rm Ti}_{0.5}}{{\rm O}_2}$CuCo0.5Ti0.5O2 (CCoTO) nanostructure synthesized via a simple chemical route. The 40-70 nm CCoTO nanoparticles with centrosymmetric crystalline structure show strong absorption in the 325-850 nm wavelength range due to the presence of different crystalline phases and surface vacancies. A Z-scan technique is used to study the electronic third-order nonlinearity of the synthesized nanoparticles, where a low-repetition-rate 120 fs laser source is employed to minimize thermal agitation-related nonlinearity. The CCoTO nanoparticles possess high surface defects due to oxygen- and copper-related vacancies, which are able to enhance the exciton oscillator strength resulting from the high value of third-order optical nonlinearity. The estimated values of nonlinear refractive index (${n_2}$n2) and nonlinear absorption coefficient ($\beta $ß) of the CCoTO are $ - {1.24}\; \times \;{{10}^{ - 15}}$-1.24×10-15 and ${3.79} \times {{10}^{ - 11}}$3.79×10-11, respectively, under ${188}\,\,{{\rm GW/cm}^2}$188GW/cm2 incident intensity. The intensity-dependent nonlinear optical property of the synthesized nanoparticles is also studied under different incident laser irradiation (62.7, 93, and ${188}\,\,{{\rm GW/cm}^2}$188GW/cm2). In the two-photon absorption (TPA)-dominated third-order nonlinear optical process, the values of ${n_2}$n2 and $\beta $ß of CCoTO are increased with intensifying the incident laser irradiation. The obtained high value of third-order optical nonlinearity of the synthesized nanostructure can be exploited in optical power limiters, pulse power reshaping, and optical switching applications.

11.
Homeopathy ; 108(2): 121-127, 2019 05.
Article in English | MEDLINE | ID: mdl-30616251

ABSTRACT

BACKGROUND: For the study of homeopathic medicines in proper perspective, emerging techniques in material science are being used. Vibrational spectroscopy is one such tool for providing information on different states of hydrogen bonding as an effect of potentization. The associated change in electrical properties is also correlated with this effect. OBJECTIVE: From the vibrational spectra, the changes in hydrogen bonding due to dilution followed by unidirectional vigorous shaking (together termed potentization) of 91% ethanol and two homeopathic medicines Chininum purum and Acidum benzoicum have been studied. The aim was to correlate the result with the change in the electrical properties of the system. METHODS: Raman spectroscopy was used to study the vibrational spectra. A U-shaped glass tube (electrochemical cell), where one arm contained bi-distilled water and the other arm alcohol/homeopathic medicine (the arms being separated by a platinum foil), was used to measure the voltage generated across two symmetrically placed platinum electrodes. RESULTS: For all samples, it was observed that potentization affected the intensity of OH stretching bands at the frequencies 3240 cm-1, 3420 cm-1 and 3620 cm-1, corresponding to strong hydrogen bond, weak hydrogen bond and broken hydrogen bond, respectively. With the increase in potency, in the presence and absence of the two medicines in ethanol, the number of OH groups linked by strong hydrogen bonds decreased, while the number of OH groups with weak hydrogen bonds increased. With the increase in potentization, the number of OH groups with broken hydrogen bonds showed a difference in the presence and absence of the medicine.The voltage measurements for ethanol show that, with succussion, the magnitude of voltage increased with the two medicines at lower potencies, but not at higher potency where the voltage is lower. Acidum benzoicum, which is acidic in nature, had higher voltage values (113mV, 130 mV and 118 mV at 6C, 30C and 200C, respectively), compared with Chininum purum, which is basic in nature (20 mV, 85 mV and 65 mV at 6C, 30C and 200C, respectively). CONCLUSION: The experimental results indicate a correlation between the vibrational and electrical properties of the homeopathic medicines Acidum benzoicum and Chininum purum at different potencies.


Subject(s)
Homeopathy , Materia Medica/chemistry , Electric Conductivity , Humans , Spectrum Analysis, Raman
12.
Langmuir ; 34(43): 12702-12712, 2018 10 30.
Article in English | MEDLINE | ID: mdl-30289725

ABSTRACT

Because of the superior optical and electrical properties, copper-impregnated size tuneable high-temperature stable manganese dioxide semiconductor quantum dots (SQDs) have been successfully synthesized by a modified chemical synthesis technique. Their size-dependent dielectric properties, semiconducting properties, and current-voltage ( I- V) characteristics have been investigated. X-ray diffraction pattern and Raman spectra confirmed that the required phase is present. Because of the different sintering temperature tuneable size of SQDs has been found and confirmed by high-resolution transmission electron microscopy. The band gap energy of the material is found to be 1.25-1.67 eV, measured from Tauc plot using UV-vis absorbance spectrum and their semiconducting properties have been confirmed by the non linear current-voltage ( I- V) behavior. Most intense green emission peak of photoluminescence (PL) spectroscopy confirms the oxygen vacancy defect state. The stoke shifting of Raman spectra, UV absorption, and PL emission are the footprint of quantum confinement effect. Incorporation of a little amount of Cu in tetragonal hollandite structure of α-MnO2 generates strain within that structure. This leads to create sufficient crystal defect state as well as rise in dielectric constant accompanied with low dielectric loss and higher ac conductivity. All these highly desirable properties make the SQDs a potential candidate for developing multifunctional photo-electronic devices. Owing to the tuneable band gap and electronic transport of the SQDs, we realized that the controllable size paves the way for designing SQDs possessing unique properties for optical and electronic device applications. Using this material as a high dielectric separator, a high-performance supercapacitor has been successfully fabricated which can light up 15 light-emitting diodes for 47 min 23 s after charging them only for 30 s.

13.
Chem Phys ; 513: 156-164, 2018 Sep 24.
Article in English | MEDLINE | ID: mdl-32287864

ABSTRACT

Graphical representation methods constitute a class of alignment-free techniques for comparative study of biomolecular sequences. In this brief commentary, we study how well some of these methods can discriminate among closely related genes.

14.
Homeopathy ; 107(2): 130-136, 2018 05.
Article in English | MEDLINE | ID: mdl-29767830

ABSTRACT

BACKGROUND: We report the effects of nanoparticles in homeopathic preparations of copper salts on the electrical properties of polymer film. Previous work showed that the incorporation of metal-derived homeopathic medicines increases the dielectric constant and alternating current (AC) conductivity of an electroactive polymer film that is commonly used as a capacitor in the electronic industry.We report here the effect of dilution of one homeopathic medicine, Cuprum arsenicosum (CuAs), at 200C potency on the electrical properties of the polymer film of poly(vinylidene fluoride-co-hexafluoropropylene). METHODS: CuAs 200c was incorporated in the film by the solution casting method. The electrical characteristics were measured at different frequencies using an inductance, capacitance, and resistance meter. Fourier transform infrared spectroscopy (FTIR) was performed to detect phase change in the polymer film due to the incorporation of CuAs. Morphology and particle size were studied using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy. RESULTS: At 10 kHz frequency, both dielectric constant and AC conductivity increased approximately 18 times for the polymer film when incorporated with 2 mL CuAs at 200C potency. FTIR indicated the increase in conducting phase, while FESEM and EDX confirmed the presence of spherical CuAs particles. CONCLUSION: The incorporation of CuAs in the electroactive polymer film enhances the conductivity and dielectric constant. We conclude that these changes arise from the change in phase of the polymer film, and because of the presence of two different metals that affects the interfacial polarization.


Subject(s)
Arsenites/chemistry , Copper/chemistry , Homeopathy , Hydroxides/chemistry , Nanoparticles/chemistry , Indicator Dilution Techniques , Polyvinyls
15.
Phys Chem Chem Phys ; 18(25): 16775-85, 2016 Jun 22.
Article in English | MEDLINE | ID: mdl-27271864

ABSTRACT

A biocompatible poly(vinylidene) difluoride (PVDF) based film has been prepared by in situ precipitation of calcium phosphate precursors. Such films were surface absorbed with two essential oils namely eucalyptus and tea tree oil. Physico-chemical characterization of the composite film revealed excellent stability of the film with 10% loading of oils in the PVDF matrix. XRD, FTIR and FESEM measurements confirmed the presence of hydroxyapatite and octacalcium phosphate in the PVDF matrix which showed predominantly ß phase. Strong bactericidal activity was observed with very low minimum bactericidal concentration (MBC) values on both E. coli and S. aureus. The composite films also resisted biofilm formation as observed by FESEM. The release of essential oils from the film showed an initial burst followed by a very slow release over a period of 24 hours. Antibacterial action of the film was found to be primarily due to the action of essential oils which resulted in leakage of vital fluids from the microorganisms. Both necrotic and apoptotic morphologies were observed in bacterial cells. Biocompatibility studies with the composite films showed negligible cytotoxicity to mouse mesenchymal and myoblast cells at MBC concentration.

16.
Phys Chem Chem Phys ; 17(2): 1368-78, 2015 Jan 14.
Article in English | MEDLINE | ID: mdl-25424552

ABSTRACT

A simple and low cost in situ process has been developed to synthesize Fe2O3-Co3O4 nanoparticles (NPs) loaded poly(vinylidene fluoride) (PVDF) thin films. The electroactive ß phase nucleation mechanism and the dielectric properties of the films have been investigated by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry and using an LCR meter. Results confirmed that the electroactive ß phase crystallization in the PVDF matrix is due to the fast nucleating or catalytic effect of the in situ NPs. Homogenous dispersion of in situ Fe2O3-Co3O4 NPs in the polymer matrix leads to strong interfacial interaction between the NPs and the polymer resulting in enhanced ß phase nucleation in PVDF and a large dielectric constant of the thin films. The observed variation in the electroactive ß phase nucleation by NPs (Fe2O3-Co3O4) and the dielectric properties of the thin films have been explained on the basis of surface charge, size, geometrical shape and extent of agglomeration of the NPs in the polymer matrix.

17.
Phys Chem Chem Phys ; 17(35): 22784-98, 2015 Sep 21.
Article in English | MEDLINE | ID: mdl-26260070

ABSTRACT

Poly(vinylidene fluoride) (PVDF) nanocomposites are recently gaining importance due to their unique dielectric and electroactive responses. In this study, GeO2 nanoparticles/PVDF and SiO2 nanoparticles/PVDF nanocomposite films were prepared by a simple solution casting technique. The surface morphology and structural properties of the as-prepared films were studied by X-ray diffraction, scanning electron microscopy, and FT-IR spectroscopy techniques. The studies reveal that the incorporation of GeO2 or SiO2 nanoparticles leads to an enhancement in the electroactive ß phase fraction of PVDF due to the strong interactions between the negatively charged nanoparticle surface and polymer. Analysis of the thermal properties of the as-prepared samples also supports the increment of the ß phase fraction in PVDF. Variation of dielectric constant, dielectric loss, and ac conductivity with frequency and loading fraction of the nanoparticles were also studied for all the as-prepared films. Dielectric constant of the nanocomposite films increases with increasing nanofiller concentration in PVDF. 15 mass% SiO2-loaded PVDF film shows the highest dielectric constant, which can be attributed to the smaller size of SiO2 nanoparticles and the homogeneous and discrete dispersion of SiO2 nanoparticles in PVDF matrix.

18.
Phys Chem Chem Phys ; 17(19): 13082-91, 2015 May 21.
Article in English | MEDLINE | ID: mdl-25915166

ABSTRACT

A facile and low cost synthesis of Ni(OH)2 nanobelt (NB) modified electroactive poly(vinylidene fluoride) (PVDF) thin films with excellent dielectric properties has been reported via in situ formation of Ni(OH)2 NBs in the PVDF matrix. The formation and morphology of the NBs are confirmed by UV-visible spectroscopy and field emission scanning electron microscopy respectively. A remarkable improvement in electroactive ß phase nucleation (∼82%) and the dielectric constant (ε ∼ 3.1 × 10(6) at 20 Hz) has been observed in the nanocomposites (NCs). The interface between the NBs and the polymer matrix plays a crucial role in the enhancement of the electroactive ß phase and the dielectric properties of thin films. Strong interaction via hydrogen bonds between Ni(OH)2 NBs and the PVDF matrix is the main reason for enhancement in ß phase crystallization and improved dielectric properties. The NC thin films can be utilized for potential applications as high energy storage devices like supercapacitors, solid electrolyte batteries, self-charging power cells, piezoelectric nanogenerators, and thin film transistors and sensors.


Subject(s)
Hydroxides/chemistry , Nanocomposites/chemistry , Nickel/chemistry , Polyvinyls/chemistry , Crystallization , Electric Impedance
19.
Dalton Trans ; 53(15): 6690-6708, 2024 Apr 16.
Article in English | MEDLINE | ID: mdl-38529641

ABSTRACT

The drawbacks inherent to traditional antibacterial therapies, coupled with the escalating prevalence of multi-drug resistant (MDR) microorganisms, have prompted the imperative need for novel antibacterial strategies. Accordingly, the emerging field of piezocatalysis in semiconductors harnesses mechanical stress to drive chemical reactions by utilizing piezo-generated free charge carriers, presenting a promising technology. To the best of our knowledge, this study is the first to provide a comprehensive overview of the eradication of pathogenic S. aureus bacteria using few-layer black phosphorus (SCBP) piezo catalyst under mechanical stimuli, along with the exploration of temperature dependent dielectric properties. The synthesis of the piezo catalysts involved a one-step cost-effective sonochemical method, and its structural, morphological, elemental, optical, and overall polarization properties were thoroughly characterized and compared with the traditional method-derived product (TABP). The synthesis-introduced defects, reduced crystalline diameters, modified bandgap (1.76 eV), nanoparticle aggregation, photoluminescence quenching, along with interfacial polarization, synergistically contribute to SCBP's exceptional dielectric response (4.596 × 107 @40 Hz), which in turn enhanced the piezocatalytic activity. When subjected to soft ultrasound stimulation at 15 kHz, the piezo catalyst SCBP demonstrated significant ROS-mediated antibacterial activity, resulting in a ∼94.7% mortality rate within 40 minutes. The impact of this study extends to cost-effective energy storage devices and advances in antibacterial therapy, opening new dimensions in both fields.


Subject(s)
Nanoparticles , Staphylococcus aureus , Anti-Bacterial Agents/pharmacology , Phosphorus , Semiconductors
20.
Biomed Mater ; 18(3)2023 05 03.
Article in English | MEDLINE | ID: mdl-37075777

ABSTRACT

Wound or injury is a breakdown in the skin's protective function as well as damage to the normal tissues. Wound healing is a dynamic and complex phenomenon of replacing injured skin or body tissues. In ancient times theCalendula officinalisandHibiscus rosa-sinensisflowers were extensively used by the tribal communities as herbal medicine for various complications including wound healing. But loading and delivery of such herbal medicines are challenging because it maintains their molecular structure against temperature, moisture, and other ambient factors. This study has fabricated xanthan gum (XG) hydrogel through a facile process and encapsulatedC. officinalisandH. rosa-sinensisflower extract. The resulting hydrogel was characterized by different physical methods like x-ray diffractometer, UV-vis spectroscopy, Fourier transform infrared spectroscopy, SEM, dynamic light scattering, electronkinetic potential in colloidal systems (ZETA) potential, thermogravimetric differential thermal analysis (TGA-DTA), etc. The polyherbal extract was phytochemically screened and observed that flavonoids, alkaloids, terpenoids, tannins, saponins, anthraquinones, glycosides, amino acids, and a few percentages of reducing sugar were present in the polyherbal extract. Polyherbal extract encapsulated XG hydrogel (X@C-H) significantly enhanced the proliferation of fibroblast and keratinocyte cell lines in comparison to the bare excipient treated cells as determined by 3-(4, 5-dimethylthiazol-2-Yl)-2, 5-diphenyltetrazolium bromide assay. Also, the proliferation of these cells was confirmed by BrdU assay and enhanced expression of pAkt. In anin-vivostudy, wound healing activity of BALB/c mice was carried out and we observed that X@C-H hydrogel showed significant result compared to the other groups (untreated, X, X@C, X@H). Henceforth, we conclude that this synthesized biocompatible hydrogel could emerge as a promising carrier of more than one herbal excipients.


Subject(s)
Hydrogels , Plants, Medicinal , Animals , Mice , Humans , Male , Hydrogels/chemistry , Wound Healing , Cell Line , Flowers , Plant Extracts/chemistry
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