Bassam El-Eswed

Biofilm formation of ESKAPE pathogens creates a major problem in healthcare-associated infections, and nutrient supply significantly contributes to biofilm structure and bacterial survival. An understanding of how various nutritional environments influence polymicrobial biofilm dynamics is important for the development of targeted antimicrobials. In the present work, biofilm formation of ESKAPE pathogens was tested under three different nutritional environments—nutrient broth with no supplementation (NB; minimal), nutrient broth with supplementation of 2% glucose + 2% sucrose (NB+G+S; moderate), and Brain Heart Infusion supplemented with 2% glucose + 2% sucrose (BHI-G+S; Rich). Furthermore, we studied the effect of bacterial mixtures on biofilm features in each medium. Standard ATCC strains of Staphylococcus aureus (S), Enterococcus faecalis (E), Klebsiella pneumoniae (K), and Pseudomonas aeruginosa (P) were grown alone or in combination as mono-, dual-, tri-, and tetra-species. Biofilm formation was determined by crystal violet spectrophotometric assay (n = nine biological replicates, with three technical replicates each). LIVE/DEAD staining and confocal laser scanning microscopy (CLSM) were used for samples with absorbance values > 0.5, including 3-D architectural analysis of viability using ImageJ software. Biofilm height was quantified by using the ZEN depth code tool. Statistical analysis included one-way ANOVA with Tukey’s post hoc test (p < 0.05), and unpaired t-tests were performed when applicable to compare variables. Biofilm formation was drastically increased in rich medium compared to moderate and minimal NB. The tetra-species cocktail SKEP reached the highest biofilm dry weight in BHI+G+S and greater elevation/viability compared to NB+G+S, whereas P. aeruginosa monospecies exhibited an opposite trend (greater elevation in NB+G+S than BHI+G+S). Interestingly, the E. faecalis and P. aeruginosa group exhibited strong biofilm characteristics in a range of nutritional environments. Confocal analysis showed structurally distinct biofilms: dense, vertical biofilms in BHI+G+S and sparse, horizontal patterns in NB+G+S. Nutrient composition significantly impacts polymicrobial biofilm formation, with nutrient-rich conditions (BHI+G+S) supporting robust viable three-dimensional structures, particularly within complex bacterial communities. These observations are of potential significance with respect to biofilm formation in hospital settings, such as in wounds, and may be used in strategies against the targeted intervention of polymicrobial infections.

Glipizide is an oral hypoglycemic medication that has many limitations in its therapeutic use due to poor aqueous solubility and low plasma half‐life. These disadvantages result in inefficient glycemic regulation and a high frequency of dosing. To develop and test different mesoporous silica nanocarriers (MSN), especially Santa Barbara Amorphous‐15 (SBA‐15), to deliver glipizide continuously and enhance the overall therapeutic effects on diabetic mice. Nano‐mesoporous carriers (Mobil Composition of Matter No. 41 [MCM‐41], SBA‐15, and Hollow Mesoporous Nanoparticles [HMNs]) were synthesized and loaded with glipizide. After assessing drug encapsulation efficiency, SBA‐15 was selected as the model for our study. SBA‐15 and SBA‐15 with surface‐modified amine groups were characterized using zeta potential, Fourier‐transform infrared spectroscopy (FTIR), scanning microscopy (SEM), and X‐ray diffraction (XRD). In vivo evaluation of SBA‐15 loaded with glipizide was conducted using streptozotocin‐induced diabetic mice to measure glucose and insulin levels. Glipizide entrapment was highest in SBA‐15 compared to other nano‐mesoporous carriers. The high surface area, large pore diameter, and uniform morphology were confirmed by characterization, which facilitates efficient loading of drugs and stable amorphous dispersion of glipizide. In vitro dissolution revealed that there was a high pH dependence: at gastric pH (1.0), SBA‐15/glipizide released approximately 25% at 2 h, and with further release thereafter, whilst at intestinal pH (7.4) it released approximately 90% at 2 h, and sustained release thereafter. Furthermore, the study on streptozotocin‐induced diabetic mice showed that SBA‐15 loaded with glipizide significantly reduced glucose levels and enhanced insulin release over 48 h compared to glipizide alone. SBA‐15 is a viable nanocarrier of glipizide that offers high encapsulation efficiency, good physicochemical characteristics, and long‐term pH‐dependent release, resulting in long‐term therapy. This intervention has the potential to improve diabetes management and patient adherence.

Three Schiff base ligands, NQ, CQ and HQ, were prepared from the reaction of quinoline-3-carbohydrazide with 2-nitrobenzaldehyde, 2-chlorobenzaldehyde and 2,4-dihydroxybenzaldehyde, respectively, and were investigated for their coordination to Cu (II), Ni(II), Co(II), Cd(II), Cr(III) and Fe(III) chlorides. The NQ preparation and the X-ray structure of NQ and CQ, as well as the transition metal complexes of NQ, CQ and HQ, were reported for the first time. FTIR, 1H-NMR, magnetic susceptibility and elemental analysis were used to study the coordination of ligands to the metal ions. Based on the magnetic susceptibility and elemental analysis results, octahedral structures of the complexes such as [CuL2Cl(OH)], [FeL2Cl2(OH)] and [CoL2Cl(OH)] were proposed for L = NQ, CQ and HQ. The relatively large Cd(II) exhibited [CdL3(OH)2]. The FTIR study revealed that NQ and CQ are coordinated to the metal ions via azomethine nitrogen and carbonyl oxygen while HQ through azomethine nitrogen and phenolic oxygen. Despite the high solvation power of DMSO solvent in 1H-NMR experiments, the azomethine HC=N peak at 9.3 ppm is the most affected by complexation with metal ions. On the other hand, quinoline nitrogen seems to be a weaker coordinating site than the azomethine nitrogen. The HQ ligand, containing phenolic groups, and its complexes with Cu and Ni were found to have inhibitory effects on human breast adenocarcinoma MCF-7 and human chronic myelogenous leukemia K562. Nevertheless, metal ions did not exhibit a significant synergistic effect on the antiproliferative activity of the ligands investigated.

There exists a multitude of pathogens that pose a threat to human and public healthcare, collectively referred to as ESKAPE pathogens. These pathogens are capable of producing biofilm, which proves to be quite resistant to elimination. Strains of A. baumannii, identified by the “A” in the acronym ESKAPE, exhibit significant resistance to amoxicillin in vivo due to their ability to form biofilm. This study aims to inhibit bacterial biofilm formation, evaluate novel silica nanoparticles’ effectiveness in inhibiting biofilm, and compare their effectiveness. Amoxicillin was utilized as a positive control, with a concentration exceeding twice that when combined with silica NPs. Treatments included pure silica NPs, silica NPs modified with copper oxide (CuO.SiO₂), sodium hydroxide (NaOH.SiO₂), and phosphoric acid (H₃PO₄.SiO₂). The characterization of NPs was conducted using scanning electron microscopy (SEM), while safety testing against normal fibroblast cells was employed by MTT assay. The microtiter plate biofilm formation assay was utilized to construct biofilm, with evaluations conducted using three broth media types: brain heart infusion (BHI) with 2% glucose and 2% sucrose, Loria broth (LB) with and without glucose and sucrose, and Dulbecco’s modified eagle medium/nutrient (DMEN/M). Concentrations ranging from 1.0 mg/mL to 0.06 µg/mL were tested using a microdilution assay. Results from SEM showed that pure silica NPs were mesoporous, but in the amorphous shape of the CuO and NaOH treatments, these pores were disrupted, while H₃PO₄ was composed of sheets. Silica NPs were able to target Acinetobacter biofilms without harming normal cells, with viability rates ranging from 61–73%. The best biofilm formation was achieved using a BHI medium with sugar supplementation, with an absorbance value of 0.35. Biofilms treated with 5.0 mg/mL of amoxicillin as a positive control alongside 1.0 mg/mL of each of the four silica treatments in isolation, resulting in the inhibition of absorbance values of 0.04, 0.13, 0.07, 0.09, and 0.08, for SiO₂, CuO.SiO₂, NaOH.SiO₂ and H₃PO₄.SiO₂, respectively. When amoxicillin was combined, inhibition increased from 0.3 to 0.04; NaOH with amoxicillin resulted in the lowest minimum biofilm inhibitory concentration (MBIC), 0.25 µg/mL, compared to all treatments and amoxicillin, whereas pure silica and composite had the highest MBIC, even when combined with amoxicillin, compared to all treatments, but performed better than that of the amoxicillin alone which gave the MBIC at 625 µg/mL. The absorbance values of MBIC of each treatment showed no significant differences in relation to amoxicillin absorbance value and relation to each other. Our study showed that smaller amoxicillin doses combined with the novel silica nanoparticles may reduce toxic side effects and inhibit biofilm formation, making them viable alternatives to high-concentration dosages. Further investigation is needed to evaluate in vivo activity.

Due to their lower energy demand, alkali-activated materials or geopolymers (GPs) are strong candidates to replace ordinary Portland cement binders in some applications. The present article attempts to investigate the possibility of incorporating plastics waste in place of silica sand filler in the GP mortars. The compressive strength, density, FTIR, XRD, BET and SEM of the prepared mortars were evaluated. Satisfactory compressive strength was achieved for metakaolin (MK)-based GP mortars containing plastic fillers (polyvinylchloride (PV), polystyrene (PS), polypropylene (PP) and polyethylene (PE)) which was dependent on the nature of plastic incorporated in the GP matrix: MKPV (30.3 MPa) > MKPS (15.8 MPa)~MKPP (15.9 MPa) > MKPE (9.1 MPa). The 28-day compressive strength of GP containing polyvinyl chloride was almost equivalent to that containing silica sand. Much lower values were obtained for the corresponding kaolin-based GPs (2.5, 2.8, 1.8 and 2.2 MPa, respectively). As reflected by FTIR absorption bands at 1447 and 1400 cm⁻¹, the addition of plastic filler reduces absorption of CO₂ from the atmosphere which enhanced dissolution of Al species from metakaolin. The morphology of GPs containing plastic fillers exhibited amorphous tissue-like structure compared to crystalline structure in the case of GP containing silica sand. However, both types of GPs exhibited lower porosity than previously prepared metakaolin-based GPs. Remarkably, poor adhesion of plastic filler to the GP binder was observed due to the inertness of plastic fillers toward alkali activators.

Simultaneous Determination of B₁, B₂, B₃, B₆, B_9, and B₁₂ Vitamins in Premix and Fortified Flour Using HPLC/DAD: Effect of Detection Wavelength: Simultaneous determination of water-soluble B vitamins is a troublesome analytical procedure since they have greatly variable structures and acid-base properties which imposed difficulties on eluting them in short time and selecting wavelength of detection. The aim of the present study was to develop a simple method that overcomes these difficulties. The method was successful in simultaneous determination of B₁, B₂, B₃, B₆, B₉, and B₁₂ in premix and fortified flour by extracting vitamins with 0.1 (w/v) of ascorbate and ethylene diamine tetra-acetic acid (EDTA) solution followed by eluting using gradient mobile phase consisting of 0.03 trifluoroacetic acid aqueous solution (pH 2.6) and acetonitrile on high performance liquid chromatography (HPLC) instrument coupled with diode array detector (DAD). Elution of vitamins was completed within 9.3min, and the lowest values obtained for limit of quantification (LOQ) for B₁, B₂, B₃, B₆, B₉, and B₁₂ were 0.6, 0.2, 0.8, 0.3, 0.5, and 0.7μg/mL, respectively, at four wavelengths of 361, 280, 265, and 210nm. In general, variation of wavelength of detection in the range from 210 to 361nm affects sensitivity but had a marginal effect on the linearity and LOQ of the developed method and its application for determining B vitamins in premix and fortified flour. The 210nm wavelength exhibited the highest sensitivity though resulted in higher values of B vitamins in fortified flour with respect to 265, 280, and 361nm. Noteworthy, determination of B₂ and B₁₂ in the premix at 361nm had relatively high RSD values compared to the lower wavelengths. Thus, wavelengths in the range from 265 to 280 may be more favorable over 210 and 361nm. The method reported in the present work does not require any sample cleanup/preconcentration steps, and chromatographic elution was achieved in 9.3min without the need for ion-pairing reagents.

Schiff bases have played significant roles in the development of inorganic or coordination chemistry. Three Schiff base (NB, CB and HB) ligands, prepared for the reaction of 2-amino-6-methoxy-benzothiazole with 2-Nitrobenzaldehyde, 2-chlorobenzaldehyde and 2,4-Dihydroxybenzaldehyed, respectively, were investigated for their transition metal complexes, which were prepared by reacting the ligand (2:1 molar ratio) with Co(II), Ni(II), Cu(II), Cd(II), Cr(III) and Fe(III) chlorides. The nature of the interaction between the metal ions and ligands (L) was studied with the aid of magnetic susceptibility, elemental analysis, FTIR and ¹H-NMR spectroscopy. Based on the magnetic superstability and elemental analysis results, octahedral structures of the complexes, such as [ML₂Cl₂] or [ML₂Cl(OH)], were proposed for Cu(II), Cd(II), Co(II) and Ni(II) in which the ligand (L:NB, CB or HB) is bidentate through the azomethine and benzothiazole nitrogen. For Cr(III) and Fe(III) complexes, octahedral ML₂Cl(OH)₂ or ML₂(OH)₃ structures were proposed, where one ligand is monodentate and the other is bidentate. The azomethine ν(-HC=N-) and ¹H-NMR peaks of NB and CB were shifted to a higher frequency and downfield, respectively, upon complexation with metal ions. The bonding of OH groups of HB to Co(II), Cu(II) and Ni(II) enables π-backdonation from these metals to the azomethine of Schiff bases and the consequent shift of ν(-HC=N-) to a lower frequency and changes in the intensity of the ¹H-NMR peak of OH. On the other hand, this backdonation was not evidenced in the FTIR of HB complexes with high-charge Cr(III) and Fe(III) ions.