3D Bioprinting of Gelatin–Xanthan Gum Composite Hydrogels for Growth of Human Skin Cells

In recent years, bioprinting has attracted much attention as a potential tool for generating complex 3D biological constructs capable of mimicking the native tissue microenvironment and promoting physiologically relevant cell–cell and cell–matrix interactions. The aim of the present study was to develop a crosslinked 3D printable hydrogel based on biocompatible natural polymers, gelatin and xanthan gum at different percentages to be used both as a scaffold for cell growth and as a wound dressing. The CellInk Inkredible 3D printer was used for the 3D printing of hydrogels, and a glutaraldehyde solution was tested for the crosslinking process. We were able to obtain two kinds of printable hydrogels with different porosity, swelling and degradation time. Subsequently, the printed hydrogels were characterized from the point of view of biocompatibility. Our results showed that gelatin/xanthan-gum bioprinted hydrogels were biocompatible materials, as they allowed both human keratinocyte and fibroblast in vitro growth for 14 days. These two bioprintable hydrogels could be also used as a helpful dressing material.

Prevalence and Antimicrobial Resistance of Paeniclostridium sordellii in Hospital Settings

(1) Background: The purpose of this study was to determine the prevalence of clostridia strains in a hospital environment in Algeria and to evaluate their antimicrobial susceptibility to antibiotics and biocides. (2) Methods: Five hundred surface samples were collected from surfaces in the intensive care unit and surgical wards in the University Hospital of Tlemcen, Algeria. Bacterial identification was carried out using MALDI-TOF-MS, and then the minimum inhibitory concentrations (MICs) of various antimicrobial agents were determined by the E-test method. P. sordellii toxins were searched by enzymatic and PCR assays. Seven products intended for daily disinfection in the hospitals were tested against Clostridium spp. spore collections. (3) Results: Among 100 isolates, 90 P. sordellii were identified, and all strains were devoid of lethal and hemorrhagic toxin genes. Beta-lactam, linezolid, vancomycin, tigecycline, rifampicin, and chloramphenicol all proved effective against isolated strains. Among all strains tested, the spores of P. sordellii exhibited remarkable resistance to the tested biocides compared to other Clostridium species. The (chlorine-based 0.6%, 30 min), (glutaraldehyde solution 2.5%, 30 min), and (hydrogen peroxide/peracetic acid 3%, 15 min) products achieved the required reduction in spores. (4) Conclusions: Our hospital’s current cleaning and disinfection methods need to be optimized to effectively remove spores from caregivers’ hands, equipment, and surfaces.

Controlled Release of Acetyl Salicylic Acid in Intelligent Hydrogel Based on Cross-linked O-Carboxymethyl Chitosan

Drug-loading hydrogels were prepared from O-carboxymethyl chitosan (O-CMCS) with a high degree of substitution and different deacetylation degree (DD) using acetylsalicylic acid as drug and glutaraldehyde as a cross-linking agent. Also, the DD’s effect on the controlled drug release performance of drug-loading particle was explored. The results showed that the hydrogels and particles were prepared from 5 g of O-CMCS solution (4.0 wt.%), 2.5 g of sodium acetylsalicylate solution (8.0 wt.%), and 1.5 mL of glutaraldehyde solution (1.0 wt.%). The interior pore size of the particle (DD = 51%) was between 50 and 100µm, and its cumulative drug release ratios in the simulated gastric and intestinal juices were of the top values. The drug release of the drug-loading particle was proved to be obviously pH sensitive and it can be applied as a colonic drug.

Mechanical testing of glutaraldehyde cross-linked mitral valves. Part one: In vitro mechanical behaviour

The aim of this study was to perform an initial assessment, in vitro, of the feasibility of using a glutaraldehyde cross-linked porcine mitral valve to retain acute functionality, focusing on assessing mitral regurgitation. Six porcine hearts were tested using an in vitro simulator. Testing was repeated following cross-linking of mitral valves; where cross-linking was achieved by placing them in a glutaraldehyde solution. The simulator enabled systolic pressure on the ventricular side of the valve to be mimicked. Following testing, mitral valve leaflets underwent Scanning Electron Microscopy of the ventricular surface of both the anterior and posterior leaflets (1 cm2 samples). The peak pressure withstood by cross-linked valves was significantly lower than for untreated valves (108 mmHg cf. 128 mmHg for untreated valves; p < 0.05). The peak pressure was typically reached 0.5 s later than for the untreated valve. While both cross-linked and untreated valves exhibited endothelium denudation, the unfixed valve had less endothelial loss. Glutaraldehyde cross-linking of porcine mitral valves may be of potential value in assessing improved bioprosthetic mitral valve replacements. However, a more immobile valve exhibiting endothelial denudation (i.e. sclerosis) was a possible concerns identified following in vitro acute assessment.

Enkapsulasi dan Karakterisasi Pelepasan Terkendali Pupuk NPK Menggunakan Kitosan Yang Ditaut Silang Dengan Glutaraldehida

<p dir="ltr"><span>Pelepasan terkendali pupuk NPK bertujuan untuk meningkatkan efisiensi penggunaan unsur hara tanaman dan juga untuk mengurangi pencemaran lingkungan. Penelitian ini bertujuan untuk menentukan pengaruh konsentrasi larutan kitosan dan glutaraldehida terhadap yield dan daya serap mikrokapsul pupuk NPK. Tujuan lain adalah menentukan karakterisasi dan analisis </span><span>release</span><span> pupuk NPK dari mikrokapsul dan juga menghitung kinetika </span><span>release</span><span>. Mikrokapsul pupuk NPK dipreparasi dengan mencampurkan pupuk NPK cair ke dalam larutan kitosan, kemudian campuran tersebutkan diteteskan ke dalam larutan glutaraldehida sambil diaduk. Mikrokapsul pupuk NPK yang terbentuk dicuci menggunakan petroleum eter dilanjutkan dengan heksana dan dikeringkan. Hasil penelitian menunjukkan bahwa peningkatan konsentrasi larutan kitosan dan glutaraldehida menghasilkan peningkatan yield, menurunkan daya serap air, dan menurunkan pupuk NPK yang </span><span>release</span><span> dari mikrokapsul pupuk NPK. Model kinetika </span><span>release</span><span> yang sesuai berdasarkan tingginya nilai R</span><span><span>2</span></span><span> adalah model order satu dan model Higuchi didapat dari mikrokapsul pupuk NPK yang dipreparasi dengan 1% (b/v) larutan kitosan dan 5% (v/v) larutan glutaraldehida. </span></p><div><span><br /></span></div><div><span id="docs-internal-guid-37238ba6-7fff-901c-6b75-dcfabd6bc250"><span>Encapsulation and Characterization of Controlled Release of NPK Fertilizer Using Glutaraldehyde-Crosslinked Chitosan.</span><span> Controlled release NPK fertilizer aims to improve the nutrient use efficiency (NUE) of plants and also to reduce environmental pollution. This study aims to determine the effect of the concentration of chitosan and glutaraldehyde solutions on the yield and absorptive ability of NPK fertilizer microcapsules. Another objective was to determine the characterization and analysis of NPK fertilizer releases from microcapsules and also </span><span>to</span><span> calculate </span><span>the</span><span> release kinetics. NPK fertilizer microcapsules were prepared by mixing liquid NPK fertilizer into a chitosan solution, and then the mixture was dripped into a glutaraldehyde solution while stirring. NPK fertilizer microcapsules formed were washed using petroleum ether, followed by hexane and dried. The results showed that an increase in</span><span>the concentration of chitosan and glutaraldehyde solutions resulted in an increase in yield, decreased water absorbency, and l</span><span>ower NPK fertilizer released from microcapsules.</span><span> The appropriate release kinetics models based on the higher R</span><span><span>2</span></span><span> value were the first-order model and the Higuchi model </span><span>obtained from microcapsules of NPK fertilizer that was prepared</span><span> with 1% (w/v) chitosan solution and 5% (v/v) glutaraldehyde solution.</span></span></div>

ANTIMICROBIAL ACTIVITY OF THE DRUG FUMIOD IN RESPECT TO ISOLATES OF CON-DITIONALLY PATHOGENIC MICRO-FLORA FROM ANIMALS WITH SIGNS OF RESPIRATORY DISEASES.

The purpose of the work is to study the anti-microbial activity of fumigation aerosols of the Fumiyod preparation using bactericidal blocks against isolates of opportunistic mi-croflora from calves and piglets with signs of infectious respiratory diseases. The work was carried out on livestock and pig farms of Volosovsky district of the Leningrad region. Samples of biomaterial (nasal swabs and nasopharyngeal swabs) were taken from dis-eased animals to determine the sensitivity of the microflora to the studied iodine-containing Fumiyod preparation (experiment) and 1% glutaraldehyde solution (control). The biomaterial was plated on elective nutrient media (milk-yolk-salt agar, blood agar, Endo medium, yolk-salt agar). Cultures of microorganisms (Klebsiella pneumonia, Str.pneumoniae, St. aureus, Pro-teus vulgaris, Pseudomonas aeruginosa, E. coli), yeast were isolated from washouts from the nasal cavity and nasopharyngial washings from calves and piglets with symp-toms of bronchopneumonia, pneumonia, bronchitis, rhinitis albicans) and fungi (Mucor sp., Aspergillus fumigatus). Using paper discs, it was found that the Fumiyod preparation in the form of fumigation aero-sols, used in the form of bactericidal check-ers, has a high bactericidal activity in vitro (microbial growth inhibition zone of more than 15 mm) in relation to all microflora isolates from calves and pigs with signs of respiratory diseases, which manifested by a wide range of antimicrobial and antimycotic effects. The final concentration of the Fumiyod preparation was revealed for the active active substance - 0.20 g / m3, in which a wider spectrum of its antimicrobial (growth suppression zone within 26-32 mm) and antimycotic (growth suppression zone within 27-31 mm ) actions com-pared with 1% glutaraldehyde (control), respective-ly, in the range of 20-25 mm and 21-24 mm.

Immobilization of Purified Fungal Laccase on Cost Effective Green Coconut Fiber and Study of its Physical and Kinetic Characteristics in Both Free and Immobilized Form

Background: Laccases are important enzymes that have numerous applications in different biotechnological sectors. Objective: The aim was to purify laccase from Aspergillus flavus PUF5, successfully immobilize it on coconut fiber and characterize different physical and kinetic properties under both free and immobilize conditions. Methods: Laccase from A. flavus PUF5 was purified using ammonium sulfate precipitation, followed by DEAE column chromatography and gel filtration using Sephadex G100. The molecular weight was determined through SDS-PAGE (12%). It was immobilized on pretreated coconut fiber through crosslinking by glutaraldehyde (4% v/v). Physical and kinetic parameters like optimum temperature, pH, thermostability, the effect of additives, activation energy, Km and Vmax for free and immobilized laccase were also analyzed. Recycling stability of the immobilized laccase was further determined. Results: The extracellular laccase (65 kDa) was purified up to homogeneity and was immobilized on acid-pretreated coconut fiber by 4% (v/v) glutaraldehyde solution at 30°C, pH 5.0. Activation energy (Ea) of free and immobilized laccase for oxidation of guaiacol was found to be 24.69 and 32.76 kJ mol-1 respectively. Immobilized laccase showed higher melting temperature (Tm) of (82.5°C) than free enzyme (73°C). Km and Vmax for free and immobilized laccase were found to be 0.67 mM, 0.70 mM and 280 U/mg, 336 U/mg respectively when guaiacol was used as substrate. Additionally, in immobilized condition laccase retained ˃80% of its initial activity after use till six repeated cycles. Conclusion: The purified laccase enzyme and the cheap immobilization seem to be a prospective process for different biotechnological and industrial applications.

Effect of Glutaraldehyde Concentration on Catalytic Efficacy of Candida rugosa Lipase Immobilized onto Silica from Oil Palm Leaves

Till date, studies that investigated the effect of glutaraldehyde concentration on catalytic efficacy of biocatalyst developed with silica-derived from oil palm leaves (OPL) as support, are unknown. The study presents the preparation of a support consisting of silica extracted from OPL coated over magnetite (G/A/SiO2-M) for the immobilization of Candida rugosa lipase (CRL). Herein, the effect of glutaraldehyde concentration on the catalytic efficacy of immobilized CRL was assessed by the enzymatic production of butyl butyrate as a model. Fourier transform infrared (FTIR) spectra and immobilization parameters indicated that covalent bound CRL on functionalized OPL-derived silica-magnetite composite activated with 4% (v/v) glutaraldehyde solution (100 mM, pH 7.0) (CRL/G/A/SiO2-M) and pretreated in toluene, resulted in a protein loading and an immobilization yield of 68.3 mg/g and 74.3%, respectively. The resultant CRL/G/A/SiO2-M biocatalyst which specific activity was 61.9 U/g catalyzed the esterification production of 76.5% butyl butyrate in just 3 h, as confirmed by analyses of the purified ester using FTIR and 1H NMR spectroscopy. Hence, the finding envisages the promising use of G/A/SiO2-M support fabricated from discarded OPL as a carrier for immobilization and activation of CRL, in conjunction to being a good alternative source of renewable silica.