Amino Groups Of Chitosan Research Articles

Application of cyclohexene oxide modified chitosan for paper preservation

Abstract A new chitosan derivative (CS-CHO) was successfully synthesized based on chitosan (CS) and cyclohexene oxide (CHO). It proved that CHO was successfully grafted onto the amino group of CS by N-alkylation reaction through the characterization of FTIR, XRD and DSC-TGA. The mechanical properties (tensile strength, folding endurance, tearing strength), optical properties (whiteness, glossiness) of the CS-CHO coated paper sample were tested. The results showed that the mechanical properties of the paper treated with 10 % CS-CHO increased significantly without changing the appearance of the paper. The paper permanence (tensile strength, folding endurance, tearing strength and pH) of the treated paper samples tested by dry-heat aging test. The results showed that the permanence of the treated paper samples was significantly improved compared with the blank aged paper samples, which indicated that CS-CHO had the function of deacidification while reinforcing the paper samples, providing the possibility for deacidification and reinforcement in one-step method and playing a positive role in the paper preservation.

Antibacterial and Antifungal Properties of Modified Chitosan Nonwovens.

Chitosan acquires bacteriostatic properties via protonation of its amino groups. However, much of the literature assumes that chitosan itself inhibits the growth of bacteria. This article presents a comparative study of chitosan nonwovens modified with various acids, including acetic, propionic, butyric, and valeric organic acids, as well as hydrochloric acid. The aim was to determine which acid salts influence the antibacterial and antifungal activity of chitosan-based materials. Two methods were used to modify (formation of ammonium salts) the chitosan nonwovens: First, acid vapors (gassing process) were used to find which salt of chitosan had the best antibacterial properties. Based on the results, the most effective acid was prepared in a solution in ethanol. The influence of the acid concentration in ethanol, the time of treatment of chitosan materials with acid solution, and the rinsing process of modified nonwovens on the antimicrobial activity of the modified materials was investigated. The modified materials were subjected to microbiological tests. Each of the modified materials was placed in bacterial inoculum. The cultures were tested on agar to observe their microbial activity. Toxicity to human red blood cells was also investigated. A reduction in the number of bacterial cells was observed for the S. aureus strain with chitosan salt modified with 10% acetic acid in ethanol. The antibacterial activity of the chitosan salts increased with the percentage of acid salts formed on the surface of the solid material (decreasing numbers of bacterial colonies or no growth). No reduction in growth was observed for the E. coli strain. The chitosan samples were either inactive or completely eliminated the bacterial cells. Antimicrobial activity was observed for chitosan salts with hydrochloric acid and acetic acid. Finally, 1H-NMR spectroscopy and FTIR spectroscopy were used to confirm the incorporation of the acid groups to the amino groups of chitosan.

An electrochemical study of the binding interaction between chitosan and MPA-CdSe QDs for the development of biocompatible theranostic nanoprobe

The strength and stability of biopolymer-modified quantum dots (QDs) for designing biocompatible nanoprobes depends on the interaction between QDs and coating of interest. Hence, the quantitative determination of interaction parameters has a crucial role in their development. This paper focuses on an electrochemical approach to determine interaction and binding parameters between the chitosan and hydrophilic Mercaptopropionic acid (MPA) - CdSe QDs. MPA- CdSe QDs were synthesized by the hot injection method and characterized by several techniques. The cyclic voltammetry study revealed the reduction in oxidation peak current of redox solution with the addition of MPA- CdSe QDs (50 × 10−12 M to 350 × 10−12 M); however, the peak current was increased with the addition of chitosan (1 × 10−13 M to 50 × 10−13 M), without any change in the oxidation potential. This may be due to the interaction of the amino group of chitosan with the carboxylate group of MPA-CdSe QDs. The interaction was analyzed in terms of binding constant and no. of binding sites, which was 7.3 × 1015 L Mol−1and 1.3, respectively. Effect of scan rate on oxidation and reduction peak current confirms an irreversible electrode reaction. The interaction was further characterized with UV–Vis/Fluorescence spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Biocompatibility of developed nano-biocomposite further evaluated by standard cell viability assay using Adenocarcinoma human alveolar basal epithelial cell line (A549) and Chinese hamster cell line (V79). Confocal microscopic studies and Z stacking were also performed to explore the efficacy of chitosan-coated MPA-CdSe QDs as a fluorescent agent for cell imaging.

A high-performance hydroxide exchange membrane enabled by Cu2+-crosslinked chitosan.

Ion exchange membranes are widely used to selectively transport ions in various electrochemical devices. Hydroxide exchange membranes (HEMs) are promising to couple with lower cost platinum-free electrocatalysts used in alkaline conditions, but are not stable enough in strong alkaline solutions. Herein, we present a Cu2+-crosslinked chitosan (chitosan-Cu) material as a stable and high-performance HEM. The Cu2+ ions are coordinated with the amino and hydroxyl groups of chitosan to crosslink the chitosan chains, forming hexagonal nanochannels (~1 nm in diameter) that can accommodate water diffusion and facilitate fast ion transport, with a high hydroxide conductivity of 67 mS cm-1 at room temperature. The Cu2+ coordination also enhances the mechanical strength of the membrane, reduces its permeability and, most importantly, improves its stability in alkaline solution (only 5% conductivity loss at 80 °C after 1,000 h). These advantages make chitosan-Cu an outstanding HEM, which we demonstrate in a direct methanol fuel cell that exhibits a high power density of 305 mW cm-2. The design principle of the chitosan-Cu HEM, in which ion transport channels are generated in the polymer through metal-crosslinking of polar functional groups, could inspire the synthesis of many ion exchange membranes for ion transport, ion sieving, ion filtration and more.

Turning food waste to antibacterial and biocompatible fungal chitin/chitosan monofilaments

Here, cell wall of a zygomycete fungus, Rhizopus delemar, grown on bread waste was wet spun into monofilaments. Using the whole cell wall material omits the common chitosan isolation and purification steps and leads to higher material utilization. The fungal cell wall contained 36.9% and 19.7% chitosan and chitin, respectively. Solid state NMR of the fungal cell wall material confirmed the presence of chitosan, chitin, and other carbohydrates. Hydrogels were prepared by ultrafine grinding of the cell wall, followed by addition of lactic acid to protonate the amino groups of chitosan, and subsequently wet spun into monofilaments. The monofilament inhibited the growth of Bacillus megaterium (Gram+ bacterium) and Escherichia coli (Gram- bacterium) significantly (92.2% and 99.7% respectively). Cytotoxicity was evaluated using an in vitro assay with human dermal fibroblasts, indicating no toxic inducement from exposure of the monofilaments. The antimicrobial and biocompatible fungal monofilaments, open new avenues for sustainable biomedical textiles from abundant food waste.

Application of chitosan/alginate nanoparticle in oral drug delivery systems: prospects and challenges

Oral drug delivery systems (ODDSs) have various advantages of simple operation and few side effects. ODDSs are highly desirable for colon-targeted therapy (e.g. ulcerative colitis and colorectal cancer), as they improve therapeutic efficiency and reduce systemic toxicity. Chitosan/alginate nanoparticles (CANPs) show strong electrostatic interaction between the carboxyl group of alginates and the amino group of chitosan which leads to shrinkage and gel formation at low pH, thereby protecting the drugs from the gastrointestinal tract (GIT) and aggressive gastric environment. Meanwhile, CANPs as biocompatible polymer, show intestinal mucosal adhesion, which could extend the retention time of drugs on inflammatory sites. Recently, CANPs have attracted increasing interest as colon-targeted oral drug delivery system for intestinal diseases. The purpose of this review is to summarize the application and treatment of CANPs in intestinal diseases and insulin delivery. And then provide a future perspective of the potential and development direction of CANPs as colon-targeted ODDSs.

Synthesis of a Bioactive Composition of Chitosan-Selenium Nanoparticles.

A biologically active composition of chitosan-selenium nanoparticles has been developed. Selenium nanoparticles are characterized by a clear bimodal size distribution: 2–3 and ~37 nm. The main active centers of complexation with nanoparticles are the amino and hydroxyl groups of chitosan. In experiments on culturing fibroblasts of the hTERT BJ-5ta cell line on sample films, high biocompatibility of the composition was shown. It was shown that the composition of chitosan-selenium nanoparticles has a corrective effect on the oxidative processes of the body, reducing the activity of free-radical oxidation in the blood of animals. This opens up prospects for the use of this complex in the composition of antioxidant and adaptogenic drugs.

Assembling Alkaline-Responsive Chitosan@Giant Liposomes through an Ultrasound-Integrated Microfluidic Approach.

This paper presents the fabrication of an alkaline-responsive drug carrier, chitosan@giant liposome (CS-GL), by using an ultrasound-integrated microfluidic approach. On the microfluidic chip, water/oil/water droplets are first prepared and then move through an area of ultrasonic radiation to improve the regional saturation of organic solvent and accelerate its removal. At the same time, phospholipid molecules in the oil phase of the droplets are efficiently self-assembled into giant liposomes (GLs). Subsequently, microfluidic channels combined with an up-down separated structure can help in the fabrication and purification of the GLs. Due to the electrostatic interaction between the amino group of chitosan and the phosphate group of phospholipids, the GLs and chitosan are assembled into CS-GLs. The change of ζ potential after this operation indicates that chitosan is coated on the surface of GLs. The formed CS-GLs are monodispersed with a 54.1 ± 0.7 μm diameter and high drug encapsulation efficiency (∼96%), and the structural integrity can be kept without leakage of contents for more than a week in an acid medium (pH = 1.2). When this structure is placed in an aqueous solution of pH = 7.8, chitosan precipitates gradually and detaches from the GL, causing its rupture. The drug encapsulated in a single CS-GL can be rapidly released within 4 s, and 99.6% of the CS-GL carriers can complete the release within 10 min.

Multifunctional chitosan non-woven fabrics modified with terylene carbon dots for selective detection and efficient adsorption of Cr(VI)

A novel terylene carbon dots (TCDs) modified on chitosan non-woven fabrics (CNF) were successfully applied to semi-quantitatively detect on a smartphone-integrated-device and efficiently remove Cr(VI) in real samples. • Terylene carbon-dots modified chitosan non-woven fabrics (CNF-TCDs). • CNF-TCDs showed high selectivity for Cr(VI) among different cations and oxyanions. • CNF-TCDs showed high sensitivity for Cr(VI) (LOD 0.15 mg/L). • CNF-TCDs exhibited efficient removal for Cr(VI) repeatedly. • CNF-TCDs semi-quantitatively detected Cr(VI) on a smartphone-integrated-device. A novel terylene carbon dots (TCDs) were successfully synthesized by a one-step solvothermal method, and further modified onto chitosan non-woven fabrics (CNF) for selective detection and effective removal of Cr(VI). Compared with TCDs, chitosan non-woven fabrics modified by carbon dots (CNF-TCDs3) exhibited higher selectivity and lower detection limit for Cr(VI) (The limit of detection (LOD) is 0.15 mg/L). In addition, CNF-TCDs3 showed a rapid and effective removal of Cr(VI), and still maintain a high relative removal rate (above 92%) after five times recirculation. The adsorption equilibrium could be reached in only 8 min, and the maximum adsorption capacity was 203 mg/g. The adsorption process conformed to the Langmuir model, and the fitting correlation is R 2 = 0.99. The fluorescence response and efficient adsorption mechanisms of the CNF-TCDs3 toward Cr(VI) were mainly attributed to the internal filtering effect and the amino and hydroxyl groups in chitosan. Significantly, this functionalized fabrics CNF-TCDs3 were successfully applied to semi-quantitatively detect on a smartphone-integrated-device and efficiently remove Cr(VI) in real samples.

Removal of Pb (II) and V (V) from aqueous solution by glutaraldehyde crosslinked chitosan and nanocomposites

In this paper, new adsorbents with high mechanical strength chitosan-graphene oxide (CS-GO) and chitosan-titanium dioxide (CS–TiO2) were synthesized by using glutaraldehyde as crosslinking agent, and the adsorption behavior of Pb (II) and V (V) on them were investigated. The materials were characterized by scanning electron microscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The effects of initial metal ion concentration and contact time on the removal of V (V) and Pb (II) by CS-GO and CS-TiO2 were investigated. Characterization results showed that the hydroxyl group of GO/TiO2 reacted with the amino group of chitosan. A comparison of the kinetic models against experimental data showed that the kinetics react system was best described by the pseudo-second-order model. indicating that chemical adsorption was the main adsorption force. the Langmuir adsorption model and Freundlich model agreed well with the experimental data. The removal capacity of Pb (II) by CS-GO and CS-TiO2 were lower than those of V (V). The uncross-linked –OH and CO were the main adsorptive sites for Pb (II) removal, while uncross-linked –OH and –NH2 played an important role in removing V (V). These findings provided insights on the removing lead and vanadium pollution.

Hydrogels on the Base of Modified Chitosan and Hyaluronic Acid Mix as Polymer Matrices for Cytostatics Delivery.

The development of biodegradable polysaccharide hydrogel matrices for cytostatic delivery can improve the therapeutic results of patients by prolonging the action of the drug, reducing its toxicity and providing additional biological activity by polysaccharides. In this work, N-succinyl chitosan/hyaluronic acid dialdehyde/cytostatic formulations have been prepared using two different chitosan grades (30 kDa and 150 kDa) and hyaluronic acid dialdehyde. The interaction of amino groups of N-succinyl chitosan and aldehydes of hyaluronic acid resulted in the formation of azomethine bonds and was demonstrated using 13C NMR. The elastic properties of the obtained hydrogels determine their use as implants. Two cytostatics—5-fluorouracil and mitomycin C were chosen as drugs because of their using both in oncology and in ophthalmology for the surgical treatment of glaucoma. Hydrogel formulations containing cytostatic were prepared and drug release was studied using in vitro dialysis method. It was established that the molecular weight of N-succinyl chitosan and rheological properties of hydrogel influenced the drug release behavior of the gelling delivery system. Formulations prepared from N-succinyl chitosan with greatest molecular weight and mitomycin C were found to be the most promising for medical application due to their rheological properties and prolonged drug release. Mild preparation conditions, simplicity of the technique, short gelation time (within a minute), 100% yield of hydrogel, suitability for drug release applications are the main advantages of the obtained hydrogels.

Chitosan molecular weights affect anthracnose incidence and elicitation of defence-related enzymes in avocado (Persea americana) cultivar ‘Fuerte’

Anthracnose decay is one of the major causes of postharvest losses of avocados (Persea americana), during marketing. Currently, Prochloraz® fungicide is used to control anthracnose at postharvest stage which poses threat to consumer safety. Therefore, this study evaluated the effects of high and low molecular weight chitosan on the control of avocado anthracnose and fruit defence mechanism. In curative inoculation, avocados ‘(Fuerte’) were inoculated via the wounds with C. gloeosporioides spore suspension (20 μL, 1 × 106 spores mL−1). Thereafter coated with different concentrations (0.5%, 1% and 1.5%) of low (LMWC) and high molecular weight (HMWC) chitosan and fruits were held at 25 °C for 5 days. The % anthracnose incidence in avocado fruits was recorded on day 5. During preventative inoculation, wounded fruits were dipped in different concentrations of LMWC or HMWC solutions, and subsequently inoculated with C. gloeosporioides suspension. Preventatively inoculated fruits were stored for 28 days at 6.5 °C, 85% RH and thereafter for 5 days at 25 °C and 75% RH to simulated market shelf condition. The % anthracnose incidence was recorded on day 5. Fruit treated with Prochloraz® and water were included as controls for both curative and preventative infected fruits. Promising chitosan coatings with the lowest anthracnose incidence and the controls were investigated for skin epicatechin content, defence-related genes; phenylalanine ammonia lyase (PAL), lipoxygenase (LOX), fatty acid elongase (avael) and desaturase (avfad 12–3), chalcone synthase (CHS) and flavonol synthase (FLS) using RT- qPCR method. The zeta potential of selected chitosan coatings was done following standard procedures. Percentage of anthracnose incidence were lowest in 1.5% LMWC (18%, 3 mm) compared to Prochloraz® (23%, 5 mm) and the untreated fruit (90%, 24 mm). The 1.5% LMWC had the highest up-regulation of PAL, avfael, avfad 12–3, CHS, FLS genes and down-regulation of LOX gene with concomitant increase in epicatechin content (340 mg kg−1) relative to other chitosan treatments, untreated and Prochloraz® treated fruits. The superior positive zeta potential of LMWC 1.5% coating corroborates its effectiveness in controlling avocado anthracnose than HMWC 1.5%. It is possible that the interaction between the positively charged chitosan amino group (-NH3+) and the negatively charged microbial cell membrane is responsible for the enhanced antifungal activity. In late season naturally infected fruits dipped in 1.5% LMWC, anthracnose incidence dropped to 28% while Prochloraz® treated fruits showed anthracnose incidence of 82% on day 8 at the market shelf. LMWC 1.5% can replace the currently used Prochloraz®.

Efficient synthesis of chitosan derivatives as clickable tools

An efficient method for the synthesis of a series of alkynoyl-chitosan derivatives having different properties is presented. Utilizing this method, we could introduce alkyne functionalities on the amino group of chitosan without the use of protection groups. We prepared two series of chitosan derivatives, one containing alkyl spacers which are soluble in organic medium while the other contains PEG spacers which have aqueous solubility. Furthermore, we could produce derivatives having varying degree of substitution on the chitosan backbone. This series of alkynoyl-chitosan derivatives would serve as a useful tool for linking other molecules through click chemistry and we have confirmed this by successfully performing the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction with small and large azide molecules to produce four series of conjugates.

Hyaluronic acid-coated chitosan nanoparticles as targeted-carrier of tamoxifen against MCF7 and TMX-resistant MCF7 cells

Tamoxifen (TMX) is used to treat hormone-receptor-positive breast cancers at early stages. This research aimed to assess the potential of NPs in targeted delivery of TMX against MCF7 and TMX-resistant MCF7 breast cancer cell lines. For this purpose, a targeted delivery system including chitosan NPs coated with hyaluronic acid (HA-CS NPs) was created and examined in vitro. Chitosan NPs were first fabricated and loaded with TMX using the ionic-gelation method to prepare a drug-delivery system. Then, TMX-loaded CS NPs were coated by crosslinking the amino groups of chitosan to the carboxylic group of hyaluronic acid. The developed TMX delivery system was then optimized and characterized for particle fabrication, drug release, and targeting against cancer cells. The HA-CS particle size was 210 nm and its zeta potential was +25 mv. The encapsulation efficiency of TMX in NPs was 55%. TMX released from the NPs in acidic pH (5–6) was higher than the physiological pH (7.4). The cytotoxic effect of TMX-loaded HA-CS NPs on MCF7 and TMX-resistant MCF7 cells was significantly higher than TMX-loaded CS NPs and free drug. The findings confirmed the significant suppressive impact of TMX-loaded HA-CS NPs on MCF7 and TMX-resistant MCF7 cancer cells compared to the TMX-loaded CS NPs and free TMX.Graphical abstract

Development of a food packaging antibacterial hydrogel based on gelatin, chitosan, and 3-phenyllactic acid for the shelf-life extension of chilled chicken

Food safety caused by microbial contamination is an important problem that is difficult to solve for the food industry. In this study, the effective antibacterial hydrogel from electrospinning nanofibers prepared using gelatin, chitosan, and 3-phenyllactic acid (PLA) after water absorption was used to improve the antibacterial performance and prolong the shelf life of chilled chicken meat. The structure, water-absorbing ability, antibacterial ability, and fresh-keeping ability of this hydrogel were characterized. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy showed that the carboxyl group in PLA reacted with the amino group in chitosan, which formed amide bond under acidic conditions. This bond enhanced the water absorption and stability of the hydrogel. Low-field nuclear magnetic resonance showed that the addition of PLA not only changed the structure of hydrogels but also changed the ratio of different states of water in the hydrogels. The swelling ratio of GCP-1 hydrogel was two times larger than that of GCP-0 hydrogel, and scanning electron micrographs showed that the GCP-1 hydrogel after water absorption had a unique spongy shape. Furthermore, the GCP-1 hydrogel effectively inactivated foodborne pathogens Staphylococcus aureus and Escherichia coli and prolonged the preservation of chilled chicken to 4 days. This study provides an innovative way to apply electrospinning nanofibers in food packaging.

Preparation of chromium (III) ion-imprinted polymer based on azo dye functionalized chitosan

The main aim of this work is the preparation of azo dye modified chitosan that was subsequently used in the ion-imprinting of Cr(III) ions to finally obtain ion-selective sorbent able to selectively combine with Cr(III) ions from water when coexisting with other similar metal ions. The azo dye derived from resorcinol and p-aminobenzoic acid was prepared and then linked to the chitosan amino groups by amide linkages utilizing EDC/NHS coupling agent. A polymeric complex of the azo dye chitosan derivative AZCS and Cr(III) ions was then prepared and treated with glyoxal solution, which cross-link the main chitosan chains in form of micro-spherical beads in presence of the coordinated Cr(III) ions that were later expelled out of the texture of the beads using acidified EDTA eluent solution while preserving the spatial and geometrical shape of the resulting Cr(III) ions chelating sites.

Novel multifunctional dual-dynamic-bonds crosslinked hydrogels for multi-strategy therapy of MRSA-infected wounds

Wound healing is a complex dynamic process involving hemostasis, inflammation, proliferation and remodeling stages. It is urgent need to develop multifunctional hydrogels to treat multiple links of wound healing. In this work, we designed novel multifunctional dual-dynamic-bonds crosslinked hydrogels through the electrostatic interaction between phenylboric acid and the amino group of chitosan, and the dynamic borate ester bond between phenylboric acid and the catechol structure of PDA-modified CNTs. This dual dynamic cross-linking mechanism endowed hydrogels with very fast self-healing properties, which could quickly form a whole dressing after being injected into the wound site. The phenylboric acid and catechol structures endowed hydrogels with excellent adhesion properties, the adhesion strength to pig skin was up to 27.6 kPa, could be used for hemostasis in vivo. Moreover, hydrogels displayed the advantages of injectable, rapid shape adaptation, antioxidant, biocompatibility, blood compatibility, electrical conductivity and photothermal antibacterial properties. In the MRSA-infected wound model, hydrogels could effectively reduce the expression level of wound inflammatory factors, accelerate collagen deposition, epithelial tissue and vascular regeneration, and thus promote wound healing. This work provides a new idea for the design of multi-strategy therapy for wound healing and has broad clinical application prospects.

Synthesis and Characterization of Novel Uracil-Modified Chitosan as a Promising Adsorbent for Efficient Removal of Congo Red Dye.

Novel Uracil-modified chitosan (UCs) adsorbent has successfully been synthesized through a four-step method during which the amino groups of chitosan have been protected, then epoxy nuclei have been incorporated, afterwards the latter have been opened using 6-amino-1,3-dimethyl uracil, and finally the amino groups have been regained via removing the protection. Its structure was checked using FTIR, XRD and SEM techniques. The adsorption capacity of UCs for anionic Congo Red (CR) dye was studied under various conditions. It decreased significantly with increasing the solution pH value and dye concentration, while increased with increasing temperature. The adsorption of UCs for CR dye at different temperatures, solution pH and dye concentrations fitted to the kinetic model of pseudo-second order and Elovich model. The intraparticle diffusion model showed that the adsorption process involves multi-step process. The isotherm of CR dye adsorption by UCs conforms to the Langmuir isotherm model indicating the monolayer nature of adsorption. The maximum monolayer coverage capacity, qmax, was 434.78 mg g−1. Studying the thermodynamic showed that the adsorption of CR dye onto UCs was endothermic as illustrated from the positive value of enthalpy (21.37 kJ mol−1). According to the values of ΔG°, the adsorption process was spontaneous at all selected temperatures. The value of ΔS° showed an increase in randomness for the adsorption of CR dye by UCs. The value of activation energy was 18.40 kJ mol−1.

Regeneration of aged transformer oil by adsorption using attapulgite-chitosan composite

The attapulgite-chitosan (AT-CS) composites were prepared from attapulgite (ATP) and chitosan (CS). The composites were characterized using Fourier transform infrared (FTIR) spectroscopy and Brunner Emmet Teller (BET). There existed interaction between the hydroxyl groups on the surface of ATP with the oxygen-containing and amino groups of CS. The specific surface area of the AT-CS was higher than that of ATP, increased by 60.47%, which was 189.1272 m2/g. The physico-chemical properties of the regenerated oil after adsorption were found to approach the fresh oil. Moreover, Gas Chromatography-Mass Spectrometry (GC–MS) was used to observe that the oxidation by-products in the aged oil were removed by the AT-CS composite, clearly demonstrating the potential of using AT-CS as an adsorbent for transformer oil regeneration.

DFT Study of Chitosan Ascorbate Nanoparticles Structure

In recent years, use of chitosan (CS) nanoparticles as nanocarriers has received much attention due to their biodegradability, biocompatibility, and non-toxicity. CS nanoparticles containing drugs, flavors, enzymes, and antimicrobial agents can maintain their activity. Such nanoparticles can stimulate the stabilization of ascorbic acid (AA) and improve controlled release. This study investigates the interaction of CS monomer with AA and sodium tripolyphosphate (TPP) using density functional theory (DFT) during the formation of chitosan ascorbate (CA) nanostructure (CAN). Based on existing results, the formation of the CS monomer from the complexes occurs due to the donor-acceptor interaction, which is energetically favorable in all considered interactions according to the calculations. At close range, proton transfer has been identified with interaction energies, namely CS-AА (-6.82 kcal/mol), CS-TPP (–4.56 kcal/mol) in the aqueous phase, which indicates that in the process of CAN formation, in most cases, the formation of a donor-acceptor bond occurs between the amino groups of CS with the enol group of AA and the relative coordination of CS with TPP. The introduction of the aqueous phase led to a drop in the interaction energy. Based on our results for the linking types (interaction energies), we propose a simple mechanism for their impact on the CAN formation process.