Background and aim:

The poultry meat and its products are considered ideal media for bacterial growth and spoilage, as they are highly nutritive with a favorable pH. The food industry has focused its attention on a great diversity of plant species as food preservatives. The aim of this study was to investigate the presence of Staphylococcus aureus, Escherichia coli O157: H7, and Klebsiella pneumonia in food samples and to evaluate of the antibacterial activity of some medicinal plant extracts against these bacteria.

Methods:

Raw and processed meat samples (n = 60) were collected from abattoirs and local markets. S. aureus, E. coli O157: H7, and K. pneumonia were isolated, identified by phenotypic methods, and then confirmed by 16S rRNA gene sequencing. The antibacterial activity and spectrum of essential oils and spices powder of cumin, black seeds, cloves, cinnamon, and marjoram was determined against the isolated strains in this study by microbial count and well-diffusion techniques.

Results:

A total of 33 isolates have been identified as S. aureus, 30 isolates were identified as E. coli O157: H7, and 15 isolates were identified as K. pneumonia. S. aureus, E. coli O157: H7, and K. pneumonia could be detected in both fresh and processed food with higher prevalence in the processed meat. There was a significant decrease in microbial count in treated samples either with the spices powder or essential oils of the tested medicinal plants compared to control samples during storage time period. Furthermore, while the microbial count increased in the control samples, the microbial count decreased to reach zero in almost all treated samples …

Aim

The essential protein element of spider silk ‘spidroin’ was used to assess its impact on the wound-healing process.

Methods

Spidroin nanoparticles (NPs) were prepared using poly(lactic-co-glycolic acid) polymer (PLGA/spidroin NPs) at different weight ratios (5:1, 10:1, 15:1) and were in vitro characterized. The optimized NPs were tested in vitro for release and antibacterial activity. To assess wound-healing effects, NPs were topically applied on surgically induced injuries in Allolobophora caliginosa earthworms as a robust human skin model.

Results

Optimized NPs (173 ± 3 nm) revealed considerable antibacterial effect against Staphylococcus aureus and Escherichia coli. After 4 days of NPs application on wounds, macroscopical and histological examinations revealed a significant reduction in wound and re-epithelialization times.

Conclusion

PLGA/spidroin NPs may represent a promising option for wound …

We aimed to isolate Acinetobacter baumannii (A. baumannii) from wound infections, determine their resistance and virulence profile, and assess the impact of Silver nanoparticles (AgNPs) on the bacterial growth, virulence and biofilm‐related gene expression. AgNPs were synthesized and characterized using TEM, XRD and FTIR spectroscopy. A. baumannii (n = 200) were isolated and identified. Resistance pattern was determined and virulence genes (afa/draBC, cnf1, cnf2, csgA, cvaC, fimH, fyuA, ibeA, iutA, kpsMT II, PAI, papC, PapG II, III, sfa/focDE and traT) were screened using PCR. Biofilm formation was evaluated using Microtiter plate method. Then, the antimicrobial activity of AgNPs was evaluated by the well‐diffusion method, growth kinetics and MIC determination. Inhibition of biofilm formation

and the ability to disperse biofilms in exposure to AgNPs were evaluated. The effect of AgNPs on the expression of virulence and biofilm‐related genes (bap, OmpA, abaI, csuA/B, A1S_2091, A1S_1510, A1S_0690, A1S_0114) were estimated using QRT‐PCR. In vitro infection model for analyzing the antibacterial activity of AgNPs was done using a co‐culture infection model of A. baumannii with human fibroblast skin cell line HFF‐1 or Vero cell lines. A. baumannii had high level of resistance to antibiotics. Most of the isolates harbored the fimH, afa/draBC, cnf1, csgA and cnf2, and the majority of A. baumannii produced strong biofilms. AgNPs inhibited the growth of A. baumannii efficiently with MIC ranging from 4 to 25 μg/ml. A. baumannii showed a reduced growth rate in the presence of AgNPs. The inhibitory activity and the anti‐biofilm activity of AgNPs were more pronounced against the weak biofilm producers. Moreover, AgNPs decreased the expression of kpsMII , afa/draBC,bap, OmpA,

and csuA/B genes. The in vitro infection model revealed a significant antibacterial activity of AgNPs against extracellular and intracellular A. baumannii. AgNPs highly interrupted bacterial multiplication and biofilm formation. AgNPs downregulated the transcription level of important virulence andbiofilm‐related genes. Our findings provide an additional step towards understanding the mechanisms by which sliver nanoparticles interfere with the microbial spread and persistence.

An innovative and reliable electrochemical sensor was proposed for simple, sensitive and selective determination of F⁻ ions. The sensor based on the fabrication of porous and electroactive Fe-based metal organic frameworks [MIL-101(Fe)]. It was blended with graphite powder and liquid paraffin oil to from carbon paste electrode (CPE). The MIL-101(Fe)@CPE was characterized using different techniques such as scanning electron microscope, powder X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray, cyclic voltammetry, electrochemical impedance spectroscopy, differential pulse voltammetry. The MIL-101(Fe)@CPE exhibited two redox peaks (anodic and cathodic) corresponding to Fe³⁺ and Fe²⁺, respectively. The determination of F⁻ ions based on the formation of a stable fluoroferric complex with Fe³⁺/ Fe²⁺, decreasing the currents of redox species. It was found that the anodic peak current (Ipa) is linearly proportional to the concentration of F⁻ in the range of 0.67–130 μM with a limit of detection (S/N = 3) of 0.201 μM. The electrode exhibited good selectivity towards F^- detection with no significant interferences from common anions. The as-fabricated sensor was applied for the determination of F⁻ in environmental water samples with recoveries % and RSDs % in the range of 98.1%–102.4% and 2.4%–3.7%, respectively.

A molecularly imprinted electrochemical sensor was fabricated for sensitive and selective detection of anti-COVID 19 drug favipiravir (FAV). The sensor is based on the synthesis of biomass-derived carbon (BC) and nickel disulfide nanospheres (NiS₂ NS), which were used to decorate glassy carbon electrode (GCE). Then, the gold nanoparticles (AuNPs) were electro- deposited on the surface of NiS₂ NS/BC/GCE to enhance conductivity, increase electron transfer, and aid polymerization of p-aminothiophenol (p-ATP) functional monomer. The fabrication steps were characterized using different morphological and electrochemical techniques. Variables affecting the formation of molecularly imprinted layers and the determination of FAV were optimized. Under optimum conditions, the oxidation current (Ipa) was increased upon addition of FAV in the range of 0.42–1100 nM with a limit of detection (LOD, S/N) of 0.13 nM. The as-fabricated sensor possesses several advantages such as high sensitivity and selectivity, good reproducibility, and acceptable stability. Furthermore, the proposed molecularly imprinted –based electrochemical sensor was efficiently applied for the determination of FAV in tablets and human serum samples with recoveries % of 99.2 to 102.1 % and RSDs % in the range of 2.4–3.2 %, which confirms the reliability of the sensor to detect FAV in different matrices.

Graphical abstract

Copper based-metal organic frameworks modified with gold nanoparticles (AuNPs@Cu-MOF) was fabricated via facile approach. The nanocomposite was used to decorate glassy carbon electrode (GCE) for the electrochemical sensing of D- penicillamine (D-PA). The nanocomposite was characterized using different techniques such as scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDX), powder X-ray spectroscopy (PXRD), thermogravimetry (TGA), nitrogen adsorption–desorption isotherms, and Fourier Transform infrared spectroscopy (FTIR). Formation of a new anodic peak of Cu(II)-D-PA complex at + 0.38 V was used to detect D-PA. Cyclic and square wave voltammetric studies proved that AuNPs elevated the conductivity of Cu-MOF. The sensor exhibited wide linear range (0.4–75 × 10⁻⁷ M) and low detection limit (0.11 × 10⁻⁷ M) with a good sensitivity (0.9 ± 0.01 μA/μM). It was successfully applied for the estimation of D-PA in different real samples with recoveries % and relative standard deviations % (RSDs %) in the range of 95.6–102.5% and 2.4–3.3%, respectively.

An one-pot hydrothermal method was developed for synthesis of carbon quantum dots co-doped with copper and nitrogen (Cu, N@CQDs). The synthesized Cu, N@CQDs has unique advantages such as high fluorescence quantum yield (39.1%) and high catalytic activity. Oxidative coupling of amoxicillin (AMX) with 4-aminoantipyrine (4-NH₂-APE) in the presence of H₂O₂ as an oxidant to produce pink quinoneimine chromogen was carried out with the aid of Cu, N@CQDs as a peroxidase-like catalyst. This system was used for the colorimetric and fluorometric assays of AMX with reliable results. Colorimetric method is based on the measurement of a pink-colored product at λ_max = 505 nm while the fluorometric assay is based on the quenching of the fluorescence emission of Cu, N@CQDs at 440 nm after excitation at 370 nm. For the colorimetric method, the absorption intensity linearly increased over the concentration range 4.3–110.0 µM with LOD (S/N = 3) of 1.3 µM. For the fluorometric method, the emission intensity of Cu, N@CQDs linearly decreased upon addition of AMX in the concentration range 0.2–120.0 µM with a limit of detection (LOD, S/N = 3) of 0.06 µM. The proposed system was applied to the determination of AMX in different real samples such as pharmaceutical capsules, human serum, milk, and conduit water samples with recoveries in the range 95.8–104.1% and relative standard deviation (RSD %) less than 4.1%.

A simple, cost-effective, and convenient bimodal strategy for the detection of toxic flavonoid rutin was proposed. The strategy depends on fluorometric and electrochemical determination of rutin using new type of nitrogen and sulfur co-doped carbon dots (N, S@C-dots). The fluorescence detection based on quenching the emission of N, S@C-dots by rutin through inner-filter effect (IFE), while the electrochemical detection based on direct oxidation of rutin at glassy carbon electrode (GCE) modified with N, S@C-dots. Many factors affecting fluorometric and electrochemical measurements were optimized. The decrease of emission intensity and the increase of the electrochemical signal are linear over the concentration range of 0.02−92.3 μM and 0.2−130 × 10⁻⁸ M, respectively. The limits of detections (LODs) were found to be 8.0 nM and 0.8 nM for the fluorometric and electrochemical methods, respectively. Moreover, short response times (2.0 and 2.5 min) were achieved using the fluorometric and electrochemical methods, respectively. The selectivity of the fluorometric sensor towards rutin was enhanced; in the presence of other interfering flavonoids; by the addition of bovine serum albumin (BSA).

A gold nanoparticle–modified copper-based metal organic framework (Au NPs@Cu-BDC) was fabricated for the electrochemical determination of cysteine (Cys-SH). The nanocomposites were characterized using different techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), powder X-ray spectroscopy (PXRD), thermogravimetry (TGA), nitrogen adsorption–desorption isotherms, and Fourier transform infrared spectroscopy (FTIR). Formation of a new anodic peak of Cu(II)-Cys complex at + 0.43 V was used to detect Cys-SH. Cyclic and square wave voltammetric studies proved that the Au NPs enhanced the conductivity of Cu-BDC. The proposed electrode exhibited a linear range of 0.0015–10.5 μM and low detection limit of 0.0004 μM with a good sensitivity of 0.78 ± 0.01 μA μM. The as-fabricated electrode was successfully used for the estimation of Cys-SH in real samples (human plasma, urine, and saliva) with recovery % of 99–100% and RSD % of 2.7–3.6%, respectively.