Heterogeneous Membrane and Coated Wire Type Electrode with Chitosan as Ionophore in the Potentiometric Determination of Glutamate: Comparative Study

This study reports on two types of glutamate sensors based on chitosan, i) heterogeneous membrane and ii) coated wire (CWE). The linearity ranges are: i) membrane, 1.0×10^?5 to 1.0×10^?1 M and ii) CWE, 1.0×10^?5 to 1.0×10^?3 M. The LODs, and pH ranges are i) membrane, 5.0×10^?6 M and 4–8 and ii) CWE, 1.0×10^?5 M and 3–5, respectively. The presence of ionic species normally found in foodstuffs did not interfere in both electrodes. Interference in CWE was minimized by prior dilution of the sample. The CWE was further investigated for on‐line analysis. The material for proposed electrodes was cheaper and environmental friendly. Hence, they were suggested as alternative tools for the analysis of glutamate.     

Interference of chitosan in glucose analysis by high-performance liquid chromatography with evaporative light scattering detection

The purpose of this work was to quantify glucose in aqueous solutions containing chitosan by high-performance liquid chromatography (HPLC) with evaporative light scattering detection (ELSD). Chitosan is a natural compound that is used alone or as an additive in several formulations. Microencapsulation of bioactive compounds such as glucose, by means of chitosan, is being explored, but difficulties arise when glucose needs to be determined in the presence of chitosan. HPLC is the technique most commonly used for glucose analysis, and ELSD may offer advantages (e.g. sensitivity and the possibility of operating in gradient mode) compared with other detectors. The influence of chitosan in the analysis of glucose by HPLC with ELSD was investigated at different pH values of the aqueous solutions. Isocratic elution with an acetonitrile/water mixture (80:20, v/v) and water washing between runs were the best options to avoid the mucoadhesive properties of chitosan, which are responsible for column degradation and variability of the retention time of glucose. The developed methodology was considered completely adequate for rapid glucose analysis in aqueous solutions with low pH (< 3), in the presence of chitosan.     

A simple method to fabricate a chitosan-gold nanoparticles film and its application in glucose biosensor

A novel film of chitosan-gold nanoparticles is fabricated by a direct and facile electrochemical deposition method and its application in glucose biosensor is investigated. HAuCl(4) solution is mixed with chitosan and electrochemically reduced to gold nanoparticles, which can be stabilized by chitosan and electrodeposited onto glassy carbon electrode surfaces along with the electrodeposition of chitosan. Then a model enzyme, glucose oxidase (GOD) is immobilized onto the resulting film to construct a glucose biosensor through self-assembly. The resulting modified electrode surfaces are characterized with both AFM and cyclic voltammetry. Effects of chitosan and HAuCl(4) concentration in the mixture together with the deposition time and the applied voltage on the amperometric response of the biosensor are also investigated. The linear range of the glucose biosensor is from 5.0 x 10(-5) approximately 1.30 x 10(-3) M with a Michaelis-Menten constant of 3.5 mM and a detection limit of about 13 microM.     

Chitosan-sodium alginate-polyethylene glycol-crocin nanocomposite treatment inhibits esophageal cancer KYSE-150 cell growth via inducing apoptotic cell death

BackgroundEsophageal cancer is a sixth most cause of cancer-associated mortalities worldwide with increased global prevalence in each year. It has a poor prognosis with 5-year survival rate are less than 10%.ObjectiveThe present study was focused to fabricate the chitosan-sodium alginate-polyethylene glycol-crocin nanocomposites (CSP-Cr-NCs) and evaluate its in vitro anticancer potential against the esophageal cancer KYSE-150 cells.MethodologyThe fabricated CSP-Cr-NCs were characterized using different techniques such as UV–visible spectroscopy, photoluminescence assay, DLS analysis, XRD, SEM and EDX analyses. The antimicrobial study was conducted by well diffusion technique against the S. pneumoniae, K. pneumoniae, E. coli, S. aureus, and C. albicans. The viability of CSP-Cr-NCs treated KYSE-150 and Het-1A cells were assessed by the MTT assay. The ROS production, MMP level, and apoptotic cell death in the CSP-Cr-NCs administered cells were assessed by using different fluorescent staining techniques. The cell migration of CSP-Cr-NCs treated KYSE-150 cells were assessed by wound scratch assay. The levels of TBARS, GSH, and SOD activity in the CSP-Cr-NCs treated KYSE-150 cells were assessed by kits.ResultsThe outcomes from the different characterization analyses witnessed the formation of CSP-Cr-NCs with the 100–210 nm size, tetragonal and agglomerated morphological appearances. The CSP-Cr-NCs effectively repressed the microbial growth. The CSP-Cr-NCs treated KYSE-150 cells were demonstrated the decreased cell viability and IC50 was found at 2.5 µg, furthermore it did not affected the normal Het-1A cells. The formulated CSP-Cr-NCs treatment at 2.5 and 5 µg improved the ROS production, and decreased the MMP status in the KYSE-150 cells. The elevated incidences of apoptotic cells death was found in the CSP-Cr-NCs treated KYSE-150 cells. The CSP-Cr-NCs also inhibited the migration of KYSE-150 cells. The increased TBARS content and decreased GSH and SOD activity was also found in the CSP-Cr-NCs treated KYSE-150 cells.ConclusionOur findings proved that the formulated CSP-Cr-NCs treatment effectively inhibited the esophageal cancer KYSE-150 cell growth via increasing ROS production and apoptotic cell death. Therefore, it could be a promising anticancer candidate in the future for the esophageal cancer treatment.     

Enhancement of wound healing via topical application of natural products: In vitro and in vivo evaluations

Intact skin is the first physical barrier against all microbial infections. Thus, in the cases of wounds, burns, and skin damage, bacteria can infect and invade the deeper layers of skin to the bloodstream and other organs leading to severe illnesses. Thus, our study aims to investigate the potential activity of natural products, propolis and honeybee venom, to control wound infections with multi-drug resistant Staphylococcus aureus (MDRSA) and safely accelerate the wound healing. First, this study characterized the clinically isolated S. aureus using biochemical, molecular, and antibiotic sensitivity tests. Then, the hydrogel was prepared via mixing chitosan with honey, propolis, and venom at different ratios, followed by physicochemical characterization and biological examination. The in vivo experiment results after topical application of optimum concentrations revealed that both venom and propolis have significant antibacterial activity at different temperatures. The IC₅₀ of both propolis antioxidant and cytotoxicity assays was found to be 40.07 ± 2.18 μg/mL and 18.3 μg/mL, respectively. The cocktail bacteria showed both minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 10 µg/mL and of 300 µg/mL with venom respectively & MIC and MBC of 100 µg/mL, 300 µg/mL with propolis respectively. The use of hydrogel was effective against wound infection and enhanced wound healing during 14 days. Before starting clinical trials, further studies can be done on large animal models.     

High‐resolution separation of homogeneous chitooligomers series from 2‐mers to 7‐mers by ion‐exchange chromatography

Highly purified chitooligomers with single degree of polymerization are of significance for studying bioactivity of chitooligomers. However, there are few reports on high‐resolution preparative separation of chitooligomers, especially for those oligomers with degree of polymerization higher than 4. This study developed a high‐resolution chromatography for the preparative separation of a pure fully deacetylated chitooligomer series. A glucosamine oligomer mixture with low degree of polymerization was prepared by acid hydrolysis of a highly deacetylated chitosan. Then, six fractions were separated from the prepared oligomer mixture by ion‐exchange chromatography and analyzed by HPLC and ESI/MS, which primarily contained glucosamine dimers, trimers, tetramers, pentamers, hexamers, and heptamers, respectively, with chromatographic purities over 98% for dimers to hexamers and a purity of 93% for heptamers. The yields of a single round of separation were 75, 60, 60, 55, 35, and 20 mg for glucosamine dimers, trimers, tetramers, pentamers, hexamers, and heptamers, respectively. Furthermore, a chromatographic separation model for GlcN homomers was established. The capacity factor (k) of glucosamine oligomers and their degrees of polymerization (DPs) exhibited a good correlation, lnk = 0.786 + 0.846 lnDP, (R² = 0.997). Based on this equation, glucosamine octamers are expected to be separated by this system.