Gentamicin-Montmorillonite Intercalation Compounds as an Active Component of Hydroxypropylmethylcellulose Bionanocomposite Films with Antimicrobial Properties

The present study introduces an overview of gentamicin-clay mineral systems for applications in biomedicine and then focuses on the development of a series of gentamicin/clay hybrid materials to be used as the bioactive phase of hydroxypropylmethylcellulose (HPMC) to produce bionanocomposite membranes possessing antimicrobial activity of interest in wound-dressing applications. Gentamicin (Gt) was adsorbed from aqueous solutions into a montmorillonite (Cloisite®-Na+) to produce intercalation compounds with tunable content of the antibiotic. The hybrids were characterized by CHN chemical analysis, energy-dispersive X-ray analysis, X-ray diffraction, Fourier-transform infrared spectroscopy, and thermogravimetric analysis, confirming the intercalation of Gt by an ion-exchange mechanism. The release of Gt from the hybrids was tested in water and in buffer solution to check their stability. Hybrids with various amounts of Gt were incorporated into a HPMC matrix at various loadings and processed as films by the casting method. The resulting Gt-clay/HPMC bionanocomposites were characterized by means of field-emission scanning electron microscopy, and were also evaluated for their water-adsorption and mechanical properties to confirm their suitability for wound-dressing applications. The antimicrobial activity of the bionanocomposite films was tested in vitro toward various microorganisms (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium, Acinetobacter baumannii, and Klebsiella pneumonia), showing a complete bacterial reduction even in films with small Gt contents.

Study of the dissolution kinetics of drugs in solid dosage form with lisinopril and atorvastatin and intestinal permeability to assess their equivalence in vitro

Atorvastatin and lisinopril are a successful combination for the treatment of patients with chronic heart failure and hypertension. Study of the dissolution kinetics of drugs in solid dosage form with lisinopril and atorvastatin and intestinal permeability to assess their equivalence in vitro were described. In medium with hydrochloric acid pH 1.2, in the medium of acetate buffer solution with a pH of 4.5 and in the medium phosphate buffer solution with a pH of 6.8 for 15 min more than 85% of the active substance passes into solution, hence the dissolution profiles these drugs in these environments are similar, and the drugs in them are “very quickly soluble”. Among the in vitro models that make it possible to assess the degree of absorption of API, the most widely used culture of adenocarcinoma cells of the colon – Caco-2. The development of the analytical methodology and its validation is the final stage of both the dissolution study and the Caco-2 test, as well as the biowaver procedure. It plays the most important role in the reliability of the results for all the above procedures and tests. To study permeability, method LC-MS/MS was developed. According to the obtained results, atorvastatin and lisinopril showed low permeability. The values ​​of recovery of transport of test and control substances through the monolayer of cells of the Caco-2 line indicate that the results of the experiment can be considered reliable. The equivalence of the drugs “Lisinopril”, tablets of 10 mg and “Atorvastatin”, tablets of 10 mg, belongs to class III BCS proven by in vitro studies.

Simultaneous Adsorptive Stripping Voltammetric Analysis of Heavy Metals at Graphenated Cupferron Pencil Rods

Electroanalysis of heavy metal ions in the presence of cupferron ligands has been extensively studied due to its ability to form stable metallic coordination complexes. Herein, electrochemically reduced graphene oxide (ERGO) sheets were for the first time employed in conjunction with low-cost, disposable pencil graphite rods and in-situ plated thin mercury films (HgF) for the simultaneous detection of Cd2+, Cu2+, Pb2+, and Zn2+ in the presence of cupferron as a chelating agent by square-wave adsorptive cathodic stripping voltammetry (SW-AdCSV). The technique is based on the catalytic reduction of adsorbed cupferron-metal ion complexes at the surface of the ERGO-HgF-PGE at 0.1 V for 60 s in 0.1 M acetate buffer solution (pH 4.6). Owing to the improved electronic and surface effects associated with ERGO inclusion, improved sensitivity was further achieved. Under optimized conditions, the ERGO-HgF-PGE showed a linear relationship from 20 to 200 µg.L-1 with detection limits below the US-EPA of 0.17 μg.L-1 , 0.02 μg.L-1 , 0.17 μg.L-1 and 0.14 μg.L-1 for Cd2+, Cu2+, Pb2+ and Zn2+, respectively at a deposition time of 60 s. The ERGO-HgF-PGE exhibited highly reproducible results with negligible intermetallic interferences and applied successfully to the determination of trace metals in tap water with satisfactory results.

The Fluorescence Characteristic of AO-RB-SDS-GMFX and the Determination of Gemifloxacin

In Britton Robinson (B-R) buffer solution with pH = 7.00 and sodium dodecyl sulfate (SDS) medium, an effective energy transfer between acridine orange (AO) and Rhodamine B (RB) can occur, which can enhance the fluorescence of RB. The addition of Gemifloxacin (GMFX) can quench the fluorescence of RB. So a new method for the indirect determination of Gemifloxacin was established by AO-RB fluorescence resonance energy transfer. This method was applied to the determination of Gemifloxacin tablets. The results were consistent with those of high performance liquid chromatography (HPLC) . Experiments show that this method is simple, rapid, accurate and sensitive.

The Effectiveness of Teaching Materials Loaded with Blended Learning with a Scientific Approach on Buffer Solution Learning

The 2013 scientific-based curriculum, teachers must facilitate students to gain knowledge or skills based on the scientific method. The research aims to analyze the effectiveness of teaching materials. This type of research development, teaching materials have valid content and media. Teaching materials are declared effective if there is an increase in students' classical mastery, an increase in the achievement of basic competencies, and students can understand macroscopic, microscopic and symbolic level representations. Quantitative descriptive research method, starting from the analysis of the quality of teaching materials and diagnostic test instruments Two Tier Multiple Choice (TTMC), application of teaching materials, application of questions, data analysis of test results, classical completeness, achievement of basic competencies, and analysis of representational understanding. The research subjects were students of class XI and XII MIPA. The results of the study were obtained from the results of the student's TTMC test on the buffer solution material that had used Teaching Materials. Data analysis was done classically. The results showed that there was an increase in classical completeness by 9%, the achievement of basic competence indicators increased by 8% and concept understanding increased by 6%. So that the teaching materials developed are effective to use.

Understanding the Endocrine Disruptor and Determination of Bisphenol A by Functional Cu-BTABB-MOF/rGO Composite as Facile Rapid Electrochemical Sensor: An Experimental and DFT Investigation

A pioneering CuBTABB-MOF/rGO composite customized electrode is fabricated and utilized as a sensor towards identifying Bisphenol A (BPA) ina phosphate buffer solution of pH7.0. Composite is characterized by FTIR, Raman...

Bi/mZVI Combined with Citric Acid and Sodium Citrate to Mineralize Multiple Sulfa Antibiotics: Performance and Mechanism

The oxidative mineralization of sulfanilamide drugs (SAs) using micro-size zero-valent iron (mZVI) cooperated with a citric acid buffer solution was evaluated. In this study SM2, SMX, and SD could be removed at 66%, 89%, and 83%, respectively, in a 0.5% Bi/mZVI+CA+NaCA system within 2 h. Based on our analysis, the produced ·OH could be ascribed from the complexation between citrate iron (Fe(II)[Cit]−) and the generated H2O2 resulting from the activation of O2 on the mZVI surface in the Bi/mZVI+CA+NaCA system, further inducing the mineralization of antibiotics. The related possible degradation pathways were proposed. Two similar degradation pathways of SM2, SMX, and SD in the mixed liquid, including hydroxylation and SO2 extrusion, were solved. Meanwhile, there was an additional proposed degradation pathway for SMX to be degraded more effectively, as reflected in the opening of the N-O bond on the benzene ring. Therefore, this work provides an experimental basis and theoretical support for the efficient treatment of antibiotic wastewater in real industry by using an iron-based method.

Supplementing Glycerol to Inoculum Induces Changes in pH, SCFA Profiles and Microbiota Composition in In-Vitro Batch Fermentation

Glycerol was generally added to the inoculum as a cryoprotectant. However, it was also a suitable substrate for microbial fermentation, which may produce more SCFAs, thereby decreased pH of the fermentation broth. This study investigated the effect of supplementing glycerol to inoculum on in vitro fermentation and whether an enhanced buffer capacity of medium could maintain the pH stability during in vitro batch fermentation, subsequently improving the accuracy of short chain fatty acids (SCFAs) determination, especially propionate. Two ileal digesta were fermented by pig fecal inoculum with or without glycerol (served as anti-frozen inoculum or frozen inoculum) in standard buffer or enhanced buffer solution (served as normal or modified medium). Along with the fermentation, adding glycerol decreased the pH of fermentation broth (p < 0.05). However, modified medium could alleviate the pH decrement compared with normal medium (p < 0.05). The concentration of total propionic acid production was much higher than that of other SCFAs in anti-frozen inoculum fermentation at 24 and 36 h, thereby increasing the variation (SD) of net production of propionate. The α-diversity analysis showed that adding glycerol decreased Chao1 and Shannon index under normal medium fermentation (p < 0.05) compared to modified medium (p < 0.05) along with fermentation. PCoA showed that all groups were clustered differently (p < 0.01). Adding glycerol improved the relative abundances of Firmicutes, Anaerovibrio, unclassified_f_Selenomonadaceae, and decreased the relative abundance of Proteobacteria (p < 0.05). The relative abundances of Firmicutes, such as Lactobacillus, Blautia and Eubacterium_Ruminantium_group in modified medium with frozen inoculum fermentation were higher than (p < 0.05) those in normal medium at 36 h of incubation. These results showed that adding glycerol in inoculum changed the fermentation patterns, regardless of substrate and medium, and suggested fermentation using frozen inoculum with modified medium could maintain stability of pH, improve the accuracy of SCFA determination, as well as maintain a balanced microbial community.