Effect of the characters of chitosans used and regeneration conditions on the yield and physicochemical characteristics of regenerated products

Regeneration Approach to Enhance the Antimicrobial and Antioxidant Activities of Chitosan for Biomedical Applications

Owing to its biodegradability, non-toxicity, and biocompatibility, chitosan (Cs) is a ubiquitous biopolymer. However, applications of Cs are limited owing to the existence of strong inter- and intra-molecular hydrogen bonds within its network. To address this issue, we regenerated medium-molecular-weight Cs to enhance the physico-chemical and functional properties using a cationic approach. Accordingly, alkaline modification was employed to introduce an additional positive charge to the amine functional groups of Cs and moderately disintegrate the inter- and intra-hydrogen bonds. The chemical structure of Cs and regenerated chitosan (RCs) was confirmed through Fourier transform infrared and ¹H-NMR spectroscopy. RCs showed higher zeta potential value compared to Cs. Additionally, using X-ray diffraction, RCs exhibited low crystallinity, which can be attributed to the repulsive force caused by the positive surface charge and the destruction of hydrogen bonds. The RCs exhibited stronger antioxidant activity than Cs. Furthermore, the minimum inhibition concentrations (MICs) of RCs against Escherichia coli and Staphylococcus aureus were reduced by almost four times compared with those of Cs. The superior functional properties of RCs can be attributed to the formation of a polycationic structure after alkaline modification. Thus, RCs can be introduced as potent agents for various biomedical purposes.

Margetuximab conjugated-PEG-PAMAM G4 nano-complex: a smart nano-device for suppression of breast cancer

Abstract

Breast cancer due to its high incidence and mortality is the second leading cause of death among females. On the other hand, nanoparticle-based drug delivery is one of the most promising approaches in cancer therapy, nowadays. Hence, margetuximab- and polyethylene glycol-conjugated PAMAM G4 dendrimers were efficiently synthesized for targeted delivery of quercetin (therapeutic agent) to MDA-MB-231 breast cancer cells. Synthesized nano-complexes were characterized using analytical devices such as FT-IR, TGA, DLS, Zeta potential analyzer, and TEM. The size less than 40 nm, - 18.8 mV surface charge, efficient drug loading capacity (21.48%), and controlled drug release (about 45% of drug release normal pH after 8 h) were determined for the nano-complex. In the biomedical test, the cell viability was obtained 14.67% at 24 h of post-treatment for 800 nM concentration, and IC₅₀ was ascertained at 100 nM for the nano-complex. The expression of apoptotic Bax and Caspase9 genes was increased by more than eightfolds and more than fivefolds after treatment with an optimal concentration of nanocarrier. Also, more than threefolds of cell cycle arrest was observed at the optimal concentration synthetics, and 27.5% breast cancer cell apoptosis was detected after treatment with 100 nM nano-complex. These outputs have been indicating the potential capacity of synthesized nano-complex in inhibiting the growth of breast cancer cells.

Graphic abstract

Mimicked scaffolds based on coated silk woven fabric with gelatin and chitosan for soft tissue defect in oral maxillofacial area

Soft tissue defects in the oral maxillofacial area are critical problems for many patients and, in some cases, patients require an operation coupled with a performance scaffold substitution. In this research, mimicked anatomical scaffolds were constructed using gelatin- and chitosan-coated woven silk fibroin fabric. The morphologies, crystals, and structures were observed and then characterized using scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry, respectively. Physical performance was evaluated from the swelling behavior, mechanical properties, and biodegradation, while the biological performance was tested with fibroblasts and keratinocytes, after which cell proliferation, viability, and histology were evaluated. The results revealed that a coated woven silk fibroin fabric displayed a crystal structure of silk fibroin with amorphous gelatin and chitosan layers. Also, the coated fabrics contained residual water within their structure. The physical performance of the coated woven silk fibroin fabric with gelatin showed suitable swelling behavior and mechanical properties along with acceptable biodegradation for insertion at a defect site. The biological performances including cell proliferation, viability, and histology were suitable for soft tissue reconstruction at the defect sites. Finally, the results demonstrated that mimicked anatomical scaffolds based on a gelatin layer on woven silk fibroin fabric had the functionality that was promising for soft tissue construction in oral maxillofacial defect.

Synthesis of chitosan coated metal organic frameworks (MOFs) for increasing vancomycin bactericidal potentials against resistant S. aureus strain

Multiple drug resistant (MDR) has become a major issue in developing countries. MDR bacterial infections lead to significant increase in morbidity, mortality and cost of prolonged treatments. Therefore, designing of strategies for improving the antimicrobial potential of the therapeutic agents are highly required. Metal organic frameworks (MOFs) are highly tunable hybrid material, consist of metal ions linked together by organic bridging ligands have been used as an efficient drug delivery carrier because of their biodegradability, low toxicity and structure integrity upon loading and functionalizing process. Current study was based on the synthesis of chitosan coated MOFs with enhanced contact with S. aureus cell surface. Chitosan is deacetylated derivative of chitin and capable for non-bonding interaction with negatively charged bacterial cell leading to enhanced contact of MOFs with S. aureus. Chitosan coated MOFs were characterized with various techniques such as atomic force microscopy, scanning electron microscopy, DLS, FT-IR, TGA, DSC and Powder X-ray diffraction. They were also studied for their efficacy on resistant S. aureus, results revealed that Vancomycin bactericidal activity significantly increased upon loading in chitosan coated MOFs and caused increased inhibition of resistant S. aureus. AFM analysis of S. aureus strains clearly revealed complete distortion of morphology by treating with chitosan modified drug loaded MOFs. Findings of the current study suggest the potential of chitosan coated MOFs for reversing bacterial resistance against Vancomycin and provide new perspectives for improved antibiotic therapy of infections associated with MDR.

Lithium entrapped chitosan nanoparticles to reduce toxicity and increase cellular uptake of lithium

Lithium carbonate is an effective drug against bipolar disorders. Direct use of lithium carbonate has been reported to result in lithium toxication and pulmonary complications. With chitosan micro and nanoparticles gaining attention for their protein absorption, drug targeting and improved dissolution rate of sparingly water-soluble drugs, this work has focused on chitosan loaded Li as a possible alternative to Li alone for cellular uptake. Well standardized ionic gelation technique employed in this study resulted in Li loaded chitosan nanoparticles with hydrodynamic diameter below 300 nm and zeta potential of + 30 mV and oval morphology. Through various techniques electrostatic interaction as well as Claritin dependent endocytic pathway is suggested as facilitating 1.3 times increase in cell proliferation in lithium carbonate loaded chitosan nanoparticles treated PC12 cells. A controlled Li release to the extent of less than 50% in 48 h from the nanoparticle was observed. This observation has very high significance as it ensures that the lithium toxicity can be avoided. These results indicated that chitosan is a promising carrier for lithium carbonate and may improve its therapeutic efficacy and also overcome toxicity during its use in the treatment of neuropsychiatric disorders.