Drug-resistant bacteria are an increasingly serious threat to global public health. In particular, infections from multidrug-resistant (MDR) Gram-positive bacteria (i.e. Staphylococcus aureus) are ...growing global health concerns. In this work, we report the first use of nanoscale metal-organic frameworks (NMOFs) coencapsulating an antibiotic (vancomycin) and targeting ligand (folic acid) in one pot to enhance therapeutic efficacy against MDR S. aureus. Zeolitic imidazolate framework (ZIF-8) NMOFs, which have globular morphologies coencapsulating vancomycin and folic acid, are characterized by transmission electron microscopy, field-emission scanning electron microscopy, powder x-ray diffraction, ulltraviolet-visible spectroscopy, and dynamic light-scattering techniques. We determined that the presence of folic acid on the surface of the NMOFs is significant in the sense of effective uptake by MDR S. aureus through endocytosis. The functionalized NMOFs transport vancomycin across the cell wall of MDR S. aureus and enhance antibacterial activity, which has been confirmed from studies of the minimum inhibitory concentration, minimum bactericidal concentration, cytotoxicity of bacterial cells, and generation of reactive oxygen species. This work shows that functionalized NMOFs hold great promise for effective treatment of MDR S. aureus.
The presence of Congo red dye (CR) in industrial sewage causes a serious threat to the environment. Therefore, it is imperative to develop high-performance, low-cost functional materials to mitigate ...such issues. During past decades, polyaniline and its composites have been recognized as an emerging candidate to remove hazardous organic effluents from water. The present work demonstrates the successful elimination of CR from water in presence of newly synthesized graphite/cobalt sulfide/PANI-based ternary composites. Several morphological or physicochemical characterization tools were adopted to confirm the formation of the ternary composite and subsequent synergistic interaction between individual elements of the composites. The experimental results delineate that a maximum of ∼95.55% CR removal (%) was achieved after 120 min. Fast removal (∼5–10 min) of CR dye is observed for APS/Ternary composite system. From the fitted experimental data utilizing 1st or 2nd order rate kinetic models, it was observed that the adsorption induced degradation of CR dye and the process was chemisorptions in nature. Further, an intra-molecular diffusion model was also introduced that signifies both boundary layer diffusion or intraparticle diffusion phenomenon was responsible for CR removal. Furthermore, the cytotoxicity profile of the composite treated Congo red aqueous solution was evaluated when exposed to L929 fibroblast cells after 24 h or 72 h of exposure and the result deciphers the non-toxic nature of composite treated CR water.
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•PANI based ternary composite demonstrates 95% Congo red (CR) removal within 120 min under dark and ambient condition.•Fast removal (within 5–10 min) of CR is observed in presence of the APS/PANI Ternary composite.•The synergistic relation in the composite structure is responsible for CR degradation, as evident from experimental data.•The experimental data are fitted with different kinetic models to correlate the CR adsorption nature of the composite.•LCMS and Invitro-cytotoxicity study signify the successful remediation of CR from the water towards cleaner production.
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•Graphite/poly (m-aminobenzene sulfonic acid) composites are prepared by in-situ oxidative chemical polymerization route.•Response characteristics of EG/PABS based sensors have been ...studied in 10–100 ppm of ammonia in air at room temperature.•High sensitivity (about 282.5%), fast response (117–196 s) and recovery (9–120 s) observed for these ammonia sensor.•The response and recovery transients of the sensors were analysed by using two sites Langmuir adsorption model.•An effort has been made to explain the role of graphite and PABS towards low ppm ammonia detection.
Because of intimidating toxicity of ammonia, development of ultra-sensitive, as well as portable and energy efficient ammonia sensor is of paramount importance. Here, we report a simple as well as cost-effective synthesis protocol of graphite– poly-amino benzene sulfonic acid (Graphite -PABS) nanocomposite via an in-situ chemical oxidative polymerization pathway. The ammonia sensing characteristics of graphite – PABS composite based sensors on low cost plastic substrate has been investigated in the concentration range of 10–100 ppm of ammonia in air at room temperature. While the sensitivity for sensors comprising only PABS is about 136.38%, the graphite -PABS nanocomposites demonstrated an appreciably high value of about 282.5% towards 100 ppm of ammonia. The sensors have not only demonstrated high sensitivity, selectivity and fast recovery; they are operable at room temperature and hence consume considerably low power compared to the conventional metal-oxide sensors. Furthermore, we have fitted the response and recovery transients of conductance of graphite/PABS based cost effective sensor using two sites Langmuir adsorption kinetics to explain the plausible ammonia sensing mechanism of graphite loaded PABS sensor. Low concentration ammonia sensing characteristics of this newly synthesized graphite/PABS composite on the plastic substrate is first demonstrated by our group.
This work comprises the shape- and facet-dependent catalytic efficacies of different morphologies of CeO
, namely, hexagonal, rectangular, and square. The formation of different shapes of CeO
is ...controlled using polyvinyl pyrrolidone as a surfactant. The surface reactivity of formation of differently exposed CeO
facets is thoroughly investigated using UV-visible, photoluminescence, Raman, and X-ray photoelectron spectroscopies. A correlation between the growth of a surface-reactive facet and the corresponding oxygen vacancies is also established. Considering the tremendous contamination, caused by the textile effluents, the present study articulates the facet-dependent photocatalytic activities of pristine CeO
for complete degradation of methylene blue within 175 min. The observed degradation time deploying pristine CeO
as a catalyst is the shortest to be reported in the literature to our best knowledge.
The introduction of inorganic metal oxide nanoparticles in a polymer matrix is found to significantly modulate its optical, electrical and electrochemical properties. Here, we report the one-pot ...synthesis of SnO2-polycarbazole (PCz) nano composite via solution phase technique (in situ chemical oxidative polymerization route) for the first time. The morphological and compositional analyses of these organic-inorganic hybrid nano composites were done by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), the Fourier transform infrared (FTIR) spectroscopy and ultraviolet-visible (UV–visible) spectroscopy. The successful loading of SnO2 nanoparticles by PCz was apparent from FESEM micrographs. UV-Visible spectroscopy revealed that optical property of the pristine PCz was significantly revamped after incorporation of SnO2 nanoparticles. The Synergetic interactions between polycarbazole and tin oxide nanoparticles were apparent from the FTIR and XRD spectra. Thermal stability of the material estimated by Thermo gravimetric (TGA) analysis; which shows thermal strength is significantly increased after incorporation of SnO2 nanoparticles in the PCz matrix. The I-V curve shows good ohmic contact of the material with tin electrode and electrical conductivity of the material is significantly altered with varying the loading percentage of SnO2 nano particles in PCz matrix.
The mounting problem of antibiotic resistance of Staphylococcus aureus has prompted renewed efforts toward the discovery of novel antimicrobial agents. The present study was aimed to evaluate the in ...vitro antimicrobial activity of nanoconjugated vancomycin against vancomycin sensitive and resistant S. aureus strains. Folic acid tagged chitosan nanoparticles are used as Trojan horse to deliver vancomycin into bacterial cells. In vitro antimicrobial activity of nanoconjugated vancomycin against VSSA and VRSA strains was determined by minimum inhibitory concentration, minimum bactericidal concentration, tolerance and disc agar diffusion test. Cell viability and biofilm formation was assessed as indicators of pathogenicity. To establish the possible antimicrobial mechanism of nanoconjugated vancomycin, the cell wall thickness was studied by TEM study. The result of the present study reveals that nano-sized vehicles enhance the transport of vancomycin across epithelial surfaces, and exhibits its efficient drug-action which has been understood from studies of MIC, MBC, DAD of chitosan derivative nanoparticle loaded with vancomycin. Tolerance values distinctly showed that vancomycin loaded into nano-conjugate is very effective and has strong bactericidal effect on VRSA. These findings strongly enhanced our understanding of the molecular mechanism of nanoconjugated vancomycin and provide additional rationale for application of antimicrobial therapeutic approaches for treatment of staphylococcal pathogenesis.
The rise in antimicrobial resistance requires the development of new antibacterial agents. Herein, we develop nanocomposites by growing zinc oxide nanoparticles on the surface of chitosan (CS) ...modified graphene oxide (GO), obtaining GOatCS/ZnO as a novel antibacterial material. The crystal structures, surface functional groups and morphology were analyzed by using X-ray diffraction (XRD) pattern, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) images, respectively. The Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) of GOatCS/ZnO show more antibacterial potency towards both Gram-negative bacteria Escherichia coli (E. coli) and Gram-positive bacteria Staphylococcus aureus (S. aureus). In this study the GOatCS/ZnO expresses its more potency than reported graphene based nanocomposites. Investigation of intercellular reactive oxygen species (ROS) generation, NO generation and catalase activity in E. coli and S. aureus reveal that GOatCS/ZnO treatment also augments the intracellular bacterial killing by inducing reactive oxygen species production that causes oxidative damage. The minimal inhibition concentrations (MIC) of GOatCS/ZnO against E. coli and S. aureus are only 2.5 mu g mL super(-1) and 5 mu g mL super(-1) respectively. Compared with graphene based nanocomposite, which have been widely used as antibacterial agents, our GOatCS/ZnO shows better antibacterial effect. We envision that this study offers novel insights into antimicrobial actions and also demonstrates GOatCS/ZnO is a novel class of topical antibacterial agent in the areas of healthcare and environmental engineering.
Here, we have portrayed the development of novel polycarbazole - organic dye (methyl red) based composite material for humidity sensing application. Polycarbazole (PCz) was synthesized by well known ...chemical oxidative polymerisation method and PCz-dye composite material was developed via sonochemical technique. The porous nature of this organic moiety based composite material is apparent from FESEM micrograph. The optical property is simultaneously delineated by UV-Visible spectroscopy. The surface porosity of composite material is determined by BET analysis. This composite material is very sensitive towards humidity ranges from 8% to 97%. The best repeatability of the result is observed at very low (8%-23% RH) and very high (75%-97%) RH level. Moreover, the change in capacitance value in presence of different humidity level has been modelled using Redlich-Peterson isotherm model.
In this article, we report on direct detection of microRNAs (miRNAs) on a microarray by differential interference contrast (DIC) imaging technique. While the best resolution achieved with a ...fluorescence scanner is ∼1 μm, the DIC imaging technique adopted in our study offers the possibility of imaging individual reporting gold nanoparticles, or, in other words, individual miRNA strands. Due to its unrivalled resolution, the present technique could detect as low as 300 copies of target miRNAs in a sample volume of 1.0 μl. With the greatly improved sensitivity, the amount of total RNA needed in the assay is reduced to only a few nanograms, offering an excellent opportunity for fast and direct miRNA profiling without engaging any labeling and amplification procedure. Expression patterns of hsa-let-7 family members in healthy versus cancer cells analyzed on our microarray, are found to be consistent with the patterns obtained on a commercial microarray and those reported in the literature.
Emergence and spread of resistant parasites to the newest chemotherapeutic anti-malarial agents are the biggest challenges against malaria control programs. Therefore, developing a novel effective ...treatment to reduce the overgrowing burden of multidrug resistant malaria is a pressing need. Herein, we have developed a biocompatible and biodegradable, non-toxic chitosan-tripolyphosphate-chloroquine (CS-TPP CQ) nanoparticle. CS-TPP CQ nanoparticles effectively kill the parasite through redox generation and induction of the pro- and anti-inflammatory cytokines in both sensitive and resistant parasite in vitro. The in vitro observations showed a strong inhibitory effect (p < 0.01) on pro-inflammatory cytokines more specifically on TNF-α and IFN-γ whereas CS-TPP CQ nanoparticles significantly elevated the anti-inflammatory cytokines- IL-10 and TGF-β. In addition, CS-TPP CQ nanoparticle significantly increased NO generation (p < 0.01) and altered the GSH/GSSG ratio 72 h after parasite co-culture with peripheral blood mononuclear cells culminating in the free radical induced parasite killing. CS-TPP CQ nanoparticle had an effective dose of 100 ng/ml against CQ-sensitive parasite lines (p < 0.001) whereas effective dose against CQ-resistant parasite line was 200 ng/ml CS-TPP CQ with an effective duration of 72 h (p < 0.001). Our studies suggest that CS-TPP CQ nanoparticle has a potential to modulate the pro- and anti-inflammatory responses, and to trigger the redox-mediated parasite killing. It can be a novel nano-based futuristic approach towards malaria control.
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