Microstructural and micromechanical modeling of gum-gelatin-based soft tissue engineering scaffolds.

Oral and dental diseases, including periodontal disease, are among the most common conditions in the field of dentistry. The best treatment for this complication is the use of different polymers and multi-component biological tissue prepared through the freeze-drying technique. In this study, biocompatible and biodegradable polymers, namely polyvinyl alcohol (PVA) and gelatin (GN), were used for this purpose, along with Arabian gum-hydroxyapatite (HA) for its antibacterial properties. Arabian gum, with weight percentages of 0, 2, 4, and 6 wt%, was added to the polyvinyl alcohol-gelatin composition at -55 °C for 28 h in the freezer and 48 h at -45 °C under a pressure of 0.01 mbar. The resulting porous biological tissue, with four different ratios, was tested for mechanical and biological analysis in a physiological solution. Then, the samples were analyzed using a scanning electron microscope (SEM) and X-ray diffraction (XRD) technique to study the morphology and structure of the compounds before and after placement in biological solutions. Additionally, a wettability and antibacterial test were performed on the nanocomposite specimen. The SEM observations reveal that this method can create a porous structure with a porosity of about 30-50 µm with a spherical and circular architecture, which was further improved by the addition of gum, reducing the percentage of porosity and improving the tissue's tensile strength and elastic modulus. The porosity changes showed a decrease from 72 % to 60 %, and the tensile strength increased from 53.5 kPa to 76 kPa, resulting in an elastic modulus of 510 kPa to 800 kPa. The addition of gum also reduced the rate of destruction of the biological tissue, making it more suitable for soft tissue applications. The obtained results of the pH test showed that the concentration changes were neutral. The contact angle of water droplets was measured to determine hydrophilicity, indicating an improvement in hydrophilicity after the addition of gum. The results showed that the use of PVA and gelatin, due to their ductility and suitable mechanical properties, along with Arabian gum-HA, could accelerate the healing process of dental periodontal problems.

Induced effect of Ca2+ and Al3+ on chaetominine synthesis by Aspergillus fumigatus CY018 under submerged fermentation.

Chaetominine (CHA), an alkaloid with a biological activity obtained from Aspergillus fumigatus CY018, has strong anticancer activity against the human leukemia cells. However, its physiological and biochemical research is limited by CHA yield in the liquid-state fermentation, which is a problem that urgently needs effective biological solution. In this work, Ca2+ and Al3+ were found to have a strong promoting effect on CHA production after multiple metal ions screening. Then, the addition condition of Ca2+ and Al3+ was, respectively, optimized CHA production and dry cell weight. The intermediate metabolites were increased with coaddition of Ca2+ and Al3+ . The activities of key enzymes of DAHPs, AroAs, and TrpCs in the CHA biosynthesis pathway were improved by 3.58-, 3.60-, and 3.34-fold, respectively. Meanwhile, the transcription level of laeA, dahp, cs, and trpC was upregulated by 3.22-, 12.65-, 5.58-, and 6.99-fold, respectively, by coaddition of Ca2+ and Al3+ . Additionally, the fermentation strategy was successfully scaled up to a 5-L bioreactor, in which CHA production could attain 75.6 mg/L at 336 h. This work demonstrated that Ca2+ and Al3+ coaddition was an effective strategy for increasing CHA production, and the information obtained might be useful in the fermentation of filamentous fungi with the addition of metal ions.