A CMC-g-poly(AA-co-AMPS)/Fe3O4 hydrogel nanocomposite as a novel biopolymer-based catalyst in the synthesis of 1,4-dihydropyridines.

A CMC-g-poly(AA-co-AMPS)/Fe3O4 hydrogel nanocomposite was successfully designed and prepared via graft copolymerization of AA and AMPS on CMC followed by the cross-linking addition of FeCl3/FeCl2. The synthesized hydrogel nanocomposite was characterized by Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, elemental mapping, thermogravimetric analysis/differential thermal analysis (TGA/DTA), and vibrating sample magnetometry (VSM). The CMC-g-poly(AA-co-AMPS)/Fe3O4 hydrogel nanocomposite was employed as a biocompatible catalyst for the green synthesis of 1,4-dihydropyridine (1,4-DHP) derivatives under thermal and ultrasound-assisted reaction conditions. High efficiency, low catalyst loadings, short reaction time, frequent catalyst recovery, environmental compatibility and mild conditions were found in both methods.

Replacement of Trypsin by Proteases for Medical Applications.

Background: Cell culture has a crucial role in many applications in biotechnology. The production of vaccines, recombinant proteins, tissue engineering, and stem cell therapy all need cell culture. Most of these activities needed adherent cells to move, which should be trypsinized several times until received on a large scale. Although trypsin is manufactured from the bovine or porcine pancreas, the problem of contamination by unwanted animal proteins, unwanted immune reactions, or contamination to pathogen reagents is the main problem. Objectives: This study investigated microbial proteases as a safe alternative for trypsin replacement in cell culture experiments for the detachment of adherent cells. Methods: The bacteria were isolated from the leather industry effluent based on their protease enzymes. After sequencing their 16S ribosomal deoxyribonucleic acid, their protease enzymes were purified, and their enzyme activities were assayed. The alteration of enzymatic activities using different substrates and the effect of substrate concentrations on enzyme activities were determined. The purified proteases were evaluated for cell detachment in the L929 fibroblast cells compared to trypsin. The separated cells were cultured again, and cell proliferation was determined by the MTT assay. Results: The results showed that the isolated bacteria were Bacillus pumilus, Stenotrophomonas sp., Klebsiella aerogenes, Stenotrophomonas maltophilia, and Bacillus licheniformis. Among the isolated bacteria, the highest and the lowest protease activity belonged to Stenotrophomonas sp. and K. aerogenes, with 60.34 and 11.09 U/mL protease activity, respectively. All the isolated microbial proteases successfully affected L929 fibroblast cells' surface proteins and detached the cells. A significant induction in cell proliferation was observed in the cells treated with K. aerogenes protease and B. pumilus protease, respectively (P < 0.05). Conclusions: The obtained results suggested that microbial proteases can be used as safe and efficient alternatives to trypsin in cell culture in biopharmaceutical applications.

Poly(AA-co-VPA) hydrogel cross-linked with N-maleyl chitosan as dye adsorbent: Isotherms, kinetics and thermodynamic investigation.

In this study, hydrogel polymer was synthesized by incorporation of acrylic acid (AA), vinylphosphonic acid (VPA) and N-maleyl chitosan which was prepared through the acylation reaction between maleic anhydride and chitosan. N-maleyl chitosan crosslinked P(AA-co-VPA) hydrogel was utilized for the effective adsorption of crystal violet (CV) and methylene blue (MB) dyes from aqueous solutions. The synthesized hydrogel was characterized by using FTIR, SEM, EDS, TGA-DTA, and DSC methods. The effecting parameters on adsorption of dyes such as initial concentration of dyes, temperature, pH and adsorbent polymer dose were studied. The adsorption isotherm was analyzed in different temperature using Langmuir, Freundlich, Temkin and Redlich-Peterson models and the adsorption data were well described by Redlich-Peterson isotherm model. The adsorption kinetics was analyzed using pseudo first-order, pseudo second-order, intraparticle and film diffusion models in 20, 30, 40 and 50 mg/L of dye solutions and the adsorption data were well described by pseudo-second-order model. The maximum adsorption capacity of the hydrogel polymer for removal of CV and MB in 50 mg/L of dye solutions was 64.56 mg/g and 66.89 mg/g, respectively. Thermodynamic studies recommended that the adsorption process was endothermic and spontaneous. Furthermore, the adsorbent was successfully employed for successive four cycles of adsorption-desorption.