Removal of alizarin red by supermacroporous cross-linked chitosan monolith sorbents

Here, we report the fabrication of supermacroporous monolith sorbents for acidic dye removal via chitosan cross-linking with ethylene glycol diglycidyl ether (EGDGE) in acidic medium at sub-zero temperature. The developed porous structure with the thickness of polymer walls in the range of a few microns and a high content of primary amino groups determined the high sorption capacity of the sorbents toward Alizarin Red in a broad pH range (2–8). Due to the cross-linking via hydroxyl groups of the chitosan, the static sorption capacity of the fabricated materials was higher than that of chitosan flakes, even for sorbents cross-linked at EGDGE:NH2-chitosan with molar ratio 2:1. The monolith sorbents were mechanically stable and supported flow rates up to 300 bed volumes per hour. The breakthrough curve of Alizarin Red sorption showed that the effective dynamic sorption capacity was 283 mg/g, and 100% of the dye could be removed from the solutions with concentration of 100 mg/L. The monoliths can be regenerated with 0.3s M NaOH solution and used in several consecutive cycles of sorption/regeneration without loss of efficacy

DETERMINATION OF ANTIBIOTICS (CHLORAMPHENICOL AND TETRACYCLINE) IN FOODS WITH DIFFERENT MATRICES

A food product is a multicomponent system containing proteins, fats, carbohydrates. Determination of antibiotics in this case is complicated by the influence of interfering components of different nature. Methods for determining antibiotics (chloramphenicol and tetracycline) in foods with multicomponent matrices (lipid-protein, lipid-carbohydrate) have been proposed. Techniques include antibiotics extraction using various solvents, purification of extracts and concentration of antibiotics using natural sorbents (activated carbon and silica-alumina), followed by eluting of certain components with ethanol and analyzing by high performance liquid chromatography (HPLC) with UV detection. The content of antibiotics was determined in products purchased in retail stores in Vladivostok: lime honey produced in the farms of the Primorsky Territory and the Republic of Bashkortostan, hawthorn honey produced in the farms of the Republic of Bashkortostan, and chicken liver produced in the poultry farms of the Primorsky Territory. The extraction degrees of chloramphenicol and tetracycline from honey and chloramphenicol from chicken liver have been determined by the «added-found» method. The extraction degree of chloramphenicol from honey was 90%, from chicken liver - 78%. The extraction degree of tetracycline from honey samples was 82%. The content of chloramphenicol and tetracycline in some honey samples and chloramphenicol in chicken liver samples purchased in the retail network was determined. Tetracycline and chloramphenicol were found in 2 samples of lime honey with antibiotics content of 0.052 and 0.020 mg/kg, respectively. Chicken liver samples contained from 0.007 to 0.01 mg/kg of chloramphenicol

Sponge-like Scaffolds for Colorectal Cancer 3D Models: Substrate-Driven Difference in Micro-Tumors Morphology

Macroporous scaffolds (cryogels) for the 3D cell culturing of colorectal cancer micro-tumors have been fabricated by cross-linking chitosan and carboxymethyl chitosan (CMC) with 1,4-butandiol diglycidyl ether (BDDGE) under subzero temperature. Due to the different intrinsic properties and reactivity of CMC and chitosan under the same cross-linking conditions, Young′s moduli and swelling of the permeable for HCT 116 cells cryogels varied in the broad range 3–41 kPa and 3500–6000%, respectively. We have demonstrated that the morphology of micro-tumors can be controlled via selection of the polymer for the scaffold fabrication. Although both types of the cryogels had low cytotoxicity and supported fast cell proliferation, round-shaped tightly packed HCT 116 spheroids with an average size of 104 ± 30 µm were formed in CMC cryogels (Young′s moduli 3–6 kPa), while epithelia-like continuous sheets with thickness up to 150 µm grew in chitosan cryogel (Young′s modulus 41 kPa). There was an explicit similarity between HCT 116 micro-tumor morphology in soft (CMC cryogel) or stiff (chitosan cryogel) and in ultra-low attachment or adhesive culture plates, respectively, but cryogels provided the better control of the micro-tumor’s size distribution and the possibility to perform long-term investigations of drug–response, cell–cell and cell–matrix interactions in vitro.</jats:p

The Effect of Finasteride on the Secretion of Testosterone, DHT, LH, FSH and Tissue Factors in the Testis of NMRI Mice: Finasteride and Testosterone, DHT, LH, FSH

Introduction: The aim of this study was to investigate the effect of finasteride on spermatogenesis and male fertility. To do so, the effects of finasteride were examined for hormonal assays and testicular tissue changes. Materials and Methods: This study was performed on male NMRI mice in five groups, namely control, sham, and three experimental groups that received finasteride (1, 5, and 20 mg/kg BW) for 35 days. Results: As for hormonal observations, significant reductions of DHT in all injectable doses were recorded. Yet, testosterone only increased significantly in two doses of 5 and 20 mg/kg BW. Moreover, two hormones of FSH and LH were significantly reduced in the drug-receiving groups. In the view of histological findings, sperm count and motility were markedly different between the doses of 5 and 20 mg/kg BW in the epididymis. The frequency of primary spermatocytes, spermatids, and spermatozoids was considerably decreased in groups receiving finasteride at doses of 5 and 20 mg/kg BW. However, this happened only at a dose of 20 mg/kg BW for spermatogonial cells. Conclusions: It is predicted that finasteride&nbsp; at a dose of 5 mg/kg BW and more can have side effects on male reproductive ability and spermatogenesis. &nbsp

Chitosan Cross-Linking with Acetaldehyde Acetals

Here we demonstrate the possibility of using acyclic diethylacetal of acetaldehyde (ADA) with low cytotoxicity for the fabrication of hydrogels via Schiff bases formation between chitosan and acetaldehyde generated in situ from acetals in chitosan acetate solution. This approach is more convenient than a direct reaction between chitosan and acetaldehyde due to the better commercial availability and higher boiling point of the acetals. Rheological data confirmed the formation of intermolecular bonds in chitosan solution after the addition of acetaldehyde diethyl acetal at an equimolar NH2: acetal ratio. The chemical structure of the reaction products was determined using elemental analysis and 13C NMR and FT-IR spectroscopy. The formed chitosan-acetylimine underwent further irreversible redox transformations yielding a mechanically stable hydrogel insoluble in a broad pH range. The reported reaction is an example of when an inappropriate selection of acid type for chitosan dissolution prevents hydrogel formation

Tuning Mechanical Properties, Swelling, and Enzymatic Degradation of Chitosan Cryogels Using Diglycidyl Ethers of Glycols with Different Chain Length as Cross-Linkers

Cross-linking chitosan at room and subzero temperature using a series of diglycidyl ethers of glycols (DEs)—ethylene glycol (EGDE), 1,4-butanediol (BDDE), and poly(ethylene glycol) (PEGDE) has been investigated to demonstrate that DEs can be a more powerful alternative to glutaraldehyde (GA) for fabrication of biocompatible chitosan cryogels with tunable properties. Gelation of chitosan with DEs was significantly slower than with GA, allowing formation of cryogels with larger pores and higher permeability, more suitable for flow-through applications and cell culturing. Increased hydration of the cross-links with increased DE chain length weakened intermolecular hydrogen bonding in chitosan and improved cryogel elasticity. At high cross-linking ratios (DE:chitosan 1:4), the toughness and compressive strength of the cryogels decreased in the order EGDE > BDDE > PEGDE. By varying the DE chain length and concentration, permeable chitosan cryogels with elasticity moduli from 10.4 ± 0.8 to 41 ± 3 kPa, toughness from 2.68 ± 0.5 to 8.3 ± 0.1 kJ/m3, and compressive strength at 75% strain from 11 ± 2 to 33 ± 4 kPa were fabricated. Susceptibility of cryogels to enzymatic hydrolysis was identified as the parameter most sensitive to cross-linking conditions. Weight loss of cryogels increased with increased DE chain length, and degradation rate of PEGDE-cross-linked chitosan decreased 612-fold, when the cross-linker concentration increased 20-fold