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Background In the wake of emergence of antimicrobial resistance, bioactive phytochemical compounds are proving to be important therapeutic agents. The present study envisaged in silico molecular docking as well as in vitro antimicrobial efficacy screening of identified phytochemical ligands to the dispersin (aap) and outer membrane osmoporin (OmpC) domains of enteroaggregative Escherichia coli (EAEC) and non-typhoidal Salmonella spp. (NTS), respectively. Materials and methods The evaluation of drug-likeness, molecular properties, and bioactivity of the identified phytocompounds (thymol, carvacrol, and cinnamaldehyde) was carried out using Swiss ADME, while Protox-II and StopTox servers were used to identify its toxicity. The in silico molecular docking of the phytochemical ligands with the protein motifs of dispersin (PDB ID: 2jvu) and outer membrane osmoporin (PDB ID: 3uu2) were carried out using AutoDock v.4.20. Further, the antimicrobial efficacy of these compounds against multi-drug resistant EAEC and NTS strains was determined by estimating the minimum inhibitory concentrations and minimum bactericidal concentrations. Subsequently, these phytochemicals were subjected to their safety (sheep and human erythrocytic haemolysis) as well as stability (cationic salts, and pH) assays. Results All the three identified phytochemicals ligands were found to be zero violators of Lipinski’s rule of five and exhibited drug-likeness. The compounds tested were categorized as toxicity class-4 by Protox-II and were found to be non- cardiotoxic by StopTox. The docking studies employing 3D model of dispersin and ompC motifs with the identified phytochemical ligands exhibited good binding affinity. The identified phytochemical compounds were observed to be comparatively stable at different conditions (cationic salts, and pH); however, a concentration-dependent increase in the haemolytic assay was observed against sheep as well as human erythrocytes. Conclusions In silico molecular docking studies provided useful insights to understand the interaction of phytochemical ligands with protein motifs of pathogen and should be used routinely before the wet screening of any phytochemicals for their antibacterial, stability, and safety aspects.

Background Drug-resistant pathogens and industrial dye wastes have emerged as critical global public health concerns, posing significant risks to human and animal health, as well as to environmental sustainability. Green synthesized nano absorbents were found to be a viable strategy for treating drug-resistant pathogens and in wastewater. Hence, this study endeavored the synthesis of piperine-driven nano-zinc oxide (ZnONPs) and evaluated them for antibacterial, antibiofilm, and photocatalytic disinfection potential against multi-drug resistant (MDR) foodborne strains of non-typhoidal Salmonella (NTS). Besides, the dye degradation potential of ZnONPs when exposed to UV, sunlight, and LED lights and their antioxidant capacity were assessed. Results Initially, in silico analysis of piperine revealed drug-likeliness with minimal toxicity and strong interaction between piperine and OmpC motifs of Salmonella spp. UV spectroscopy of ZnONPs revealed a prominent absorption peak at 340 nm, while PXRD analysis confirmed the hexagonal wurtzite structure of ZnONPs by exhibiting peaks at 30°, 35.6°, 41.3°, 43.6°, 44.3°, 48°, 53°, 58°, and 59.2°, which corresponded to the lattice planes (102), (110), (103), (200), (112), (004), (104), (210), and (211). Additionally, the TEM images demonstrated predominantly spherical ZnONPs with hexagonal wurtzite crystalline SAED pattern. The minimum inhibitory concentration and minimum bactericidal concentration values (µg/mL) of the ZnONPs were found to be 62.50 and 125, respectively. The ZnONPs were observed to be safe with minimal hemolysis (less than 2%) in chicken RBCs, and no cytopathic effects were observed in the MTT assay using HEK cell lines. The NPs were found to be variably stable (high-end temperatures, proteases, cationic salts, and diverse pH), and were tested safe towards commensal gut lactobacilli. Additionally, in vitro time-kill kinetic assay indicated that the MDR-NTS strains were eliminated after co-incubating with ZnONPs for 6 h. The photocatalytic studies exhibited complete bacterial elimination under visible light at 4 h. Interestingly, the ZnONPs significantly inhibited the biofilm formation in the crystal violet staining assay by MDR-NTS strains ( P  < 0.001) at 24 and 48 h. Besides, a dose-dependent reducing power assay and 2,2′- azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS •+ ) assay were exhibited. Moreover, ZnONPs significantly degraded methylene blue, crystal violet, and rhodamine-B under different light sources (sunlight, UV light, and LED). Conclusions This study revealed a sustainable one-pot method of synthesizing ZnONPs from piperine, which might be used as a viable antibacterial candidate with antioxidant, antibiofilm, and photocatalytic properties with eco-friendly implications and wastewater treatment.

The global emergence of antimicrobial resistance (AMR) needs no emphasis. In this study, the in vitro stability, safety, and antimicrobial efficacy of nanosilver-entrapped cinnamaldehyde (AgC) against multi-drug-resistant (MDR) strains of enteroaggregative Escherichia coli (EAEC) were investigated. Further, the in vivo antibacterial efficacy of AgC against MDR-EAEC was also assessed in Galleria mellonella larval model. In brief, UV-Vis and Fourier transform infrared (FTIR) spectroscopy confirmed effective entrapment of cinnamaldehyde with nanosilver, and the loading efficiency was estimated to be 29.50 ± 0.56%. The AgC was of crystalline form as determined by the X-ray diffractogram with a mono-dispersed spherical morphology of 9.243 ± 1.83 nm in electron microscopy. AgC exhibited a minimum inhibitory concentration (MIC) of 0.008–0.016 mg/mL and a minimum bactericidal concentration (MBC) of 0.008–0.032 mg/mL against MDR- EAEC strains. Furthermore, AgC was stable (high-end temperatures, proteases, cationic salts, pH, and host sera) and tested safe for sheep erythrocytes as well as secondary cell lines (RAW 264.7 and HEp-2) with no negative effects on the commensal gut lactobacilli. in vitro, time-kill assays revealed that MBC levels of AgC could eliminate MDR-EAEC infection in 120 min. In G. mellonella larvae, AgC (MBC values) increased survival, decreased MDR-EAEC counts (p < 0.001), had an enhanced immunomodulatory effect, and was tested safe to the host. These findings infer that entrapment enhanced the efficacy of cinnamaldehyde and AgNPs, overcoming their limitations when used individually, indicating AgC as a promising alternative antimicrobial candidate. However, further investigation in appropriate animal models is required to declare its application against MDR pathogens.

The present study was envisaged to employ the green synthesis and characterization of silver nanoparticles (AgNPs) using the potential probiotic strain Lactobacillus acidophilus , to assess its antibacterial as well as antibiofilm activity against multi-drug-resistant enteroaggregative Escherichia coli (MDR-EAEC) strains and to investigate their antioxidant activity. In this study, AgNPs were successfully synthesized through an eco-friendly protocol, which was then confirmed by its X-ray diffraction (XRD) pattern. A weight loss of 15% up to 182 °C with a narrow exothermic peak between 170 °C and 205 °C was observed in thermogravimetric analysis-differential thermal analysis (TGA-DTA), while aggregated nanoclusters were observed in scanning electron microscopy (SEM). Moreover, the transmission electron microscopy (TEM) imaging of AgNPs revealed a spherical morphology and crystalline nature with an optimum size ranging from 10 to 20 nm. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of green synthesized AgNPs against the MDR-EAEC strains were found to be 7.80 mg/L and 15.60 mg/L, respectively. In vitro time-kill kinetic assay revealed a complete elimination of the MDR-EAEC strains after 180 min on co-incubation with the AgNPs. Moreover, the green synthesized AgNPs were found safe by in vitro haemolytic assay. Besides, the green synthesized AgNPs exhibited significant biofilm inhibition ( P  < 0.001) formed by MDR-EAEC strains. Additionally, a concentration-dependent antioxidant activity was observed in 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. Hence, this study demonstrated potential antibacterial as well as antibiofilm activity of green synthesized AgNPs against MDR-EAEC strains with antioxidant properties and warrants further in-depth studies to explore it as an effective antimicrobial agent against MDR infections.

In recent times, gold nanoparticles (AuNPs) have attracted research attention owing to their versatility and physicochemical properties. The present study has been envisaged to investigate the photocatalytic potential of AuNPs synthesized using the cell-free supernatant of a potential probiotic strain Lactobacillus acidophilus against multi-drug-resistant (MDR) strains of enteroaggregative Escherichia coli (EAEC) and methicillin-resistant Staphylococcus aureus (MRSA). The AuNPs were synthesized in 60 min at ambient temperature using cell-free supernatant of L. acidophilus MTCC 10307. These probiosynthesized AuNPs were assessed by UV-diffuse reflection spectroscopy to obtain a characteristic peak at 565 nm. The X-ray diffraction analysis revealed the crystallinity of AuNPs, which was further confirmed using transmission electron microscopic imaging to reveal uniform-sized AuNPs (8.55 ± 1.11 nm) with spherical morphology. In an attempt to investigate the photocatalytic dye degradation potential, the probiosynthesized AuNPs completely degraded methylene blue within 60 min. Moreover, the AuNPs exhibited potential antimicrobial activity against MDR strains of EAEC and MRSA, as evidenced by the micro broth dilution technique. Furthermore, the probiosynthesized AuNPs revealed excellent photocatalytic disinfection properties (within 120 min) against the tested MDR-bacterial strains. In conclusion, the probiosynthesized AuNPs could serve as an effective photocatalyst which could further be employed for various environmental bioremediation processes, including wastewater treatment, as well as the removal of antibiotic and industrial pollutants. Graphical Abstract

The global emergence of antimicrobial resistance (AMR) needs no emphasis. In this study, the in vitro stability, safety, and antimicrobial efficacy of nanosilver-entrapped cinnamaldehyde (AgC) against multi-drug-resistant (MDR) strains of enteroaggregative Escherichia coli (EAEC) were investigated. Further, the in vivo antibacterial efficacy of AgC against MDR-EAEC was also assessed in Galleria mellonella larval model. In brief, UV-Vis and Fourier transform infrared (FTIR) spectroscopy confirmed effective entrapment of cinnamaldehyde with nanosilver, and the loading efficiency was estimated to be 29.50 ± 0.56%. The AgC was of crystalline form as determined by the X-ray diffractogram with a mono-dispersed spherical morphology of 9.243 ± 1.83 nm in electron microscopy. AgC exhibited a minimum inhibitory concentration (MIC) of 0.008–0.016 mg/mL and a minimum bactericidal concentration (MBC) of 0.008–0.032 mg/mL against MDR- EAEC strains. Furthermore, AgC was stable (high-end temperatures, proteases, cationic salts, pH, and host sera) and tested safe for sheep erythrocytes as well as secondary cell lines (RAW 264.7 and HEp-2) with no negative effects on the commensal gut lactobacilli. in vitro, time-kill assays revealed that MBC levels of AgC could eliminate MDR-EAEC infection in 120 min. In G. mellonella larvae, AgC (MBC values) increased survival, decreased MDR-EAEC counts (p < 0.001), had an enhanced immunomodulatory effect, and was tested safe to the host. These findings infer that entrapment enhanced the efficacy of cinnamaldehyde and AgNPs, overcoming their limitations when used individually, indicating AgC as a promising alternative antimicrobial candidate. However, further investigation in appropriate animal models is required to declare its application against MDR pathogens.

In this article, attempts are made to grow large size PZN-PT single crystals using high temperature solution growth method by implementing novel bottom cooling technique. The grown crystals are oriented and poled along 〈001〉 direction and obtained larger piezoelectric strain coefficient (d 33 > 2000 pm V −1 ) suitable for development of underwater acoustic sensor requirements. Flexural mode hydrophone is realized using the oriented PZN-PT single crystal discs. Finite element modeling is employed to examine the design of the flexural mode hydrophone and an equivalent circuit model is also applied to study its acoustic characteristic at two extreme boundary conditions like simply supported and clamped edge condition. The underwater acoustic response of the PZN-PT single crystal based flexural mode hydrophone is evaluated over the frequency range (100 Hz to 12 kHz) and its responses are compared with the FEM and equivalent circuit model results. The predicted results from FEM and equivalent circuit model are found to be in good agreement with the experimental results. The receiving sensitivity of the PZN-PT single crystal-based hydrophone is 12 dB higher than the PZT 5A based hydrophone in the frequency range of 2 kHz to 6 kHz. The fabricated PZN-PT single crystal-based hydrophone offers better performance than the conventional piezo ceramic based flexural hydrophone.