Molecular Weight Chitosan Research Articles

Comprehensive Enhancement of Mechanical, Water-Repellent and Antimicrobial Properties of Regenerated Seaweed and Plant-Based Paper with Chitosan Coating

Regenerated papers made from discarded natural sources, such as seaweeds or non-wood plants, are viewed as promising eco-friendly alternatives relative to conventional wood-based paper. However, due to its limited mechanical strength and higher water absorption than compared to traditional wood paper, it often results in premature structural disintegration. In order to overcome this limitation, this research introduces an efficient and comprehensive strategy of coating seaweed and plant papers with varying concentrations and molecular weights of chitosan. Increased concentration and molecular weight resulted in a greater amount of chitosan deposition, while the highest molecular weight also shows increased dissolution of soluble components of the paper. Since plants and seaweeds contain high anionic polysaccharide contents, the cationic chitosan shows high binding affinity towards paper. The resulting chitosan-coated papers demonstrate significant enhancements in water repellency and mechanical properties. In addition, the chitosan-coated papers also show significant bacterial inhibition effects due to the natural anti-microbial activity of chitosan.

Chitosan mitigates the adverse effects and improves photosynthetic activity in rice (Oryza sativa L.) seedlings under drought condition

ABSTRACT The ability of chitosan to promote rice growth, physiological traits, and photosynthetic performance in rice seedlings under drought stress was investigated. Rice seedlings (Oryza sativa L. cv. KDML105) were treated with 100 mg l−1 low and high molecular weight (MW) chitosan via a combination of seed priming and foliar spray. The seedlings were subjected to drought stress by withholding water for 4 days, which resulted in the U-shaped (scale 5) leaf rolling. The results showed that drought significantly decreased shoot and root growth. Chitosan application, particularly with high MW chitosan, improved shoot and root growth under drought stress. Chitosan treatment also alleviated the effects of drought stress by elevating relative water content, as well as reducing electrolyte leakage and malondialdehyde content. Antioxidant enzyme activities, including guaiacol peroxidase (GPX) and ascorbate peroxidase (APX), were increased in response to chitosan. Additionally, treating the plant with chitosan improved photosynthetic efficiency as evidenced by increased CO2 response, the maximum rate of Rubisco carboxylase activity (Vcmax), and photosynthetic rate. We conclude that the exogenous application of chitosan aids the plant in coping with the severity of drought stress. While both low and high MW chitosans were effective at alleviating the effect of drought on rice seedlings, high MW chitosan might have a slight advantage with respect to increased effective duration.

Eugenol encapsulation into conventional liposomes and chitosan-coated liposomes: A comparative study

The aim of this study is to investigate the effect of chitosan coating layer and molecular weight on the characteristics of liposomes encapsulating eugenol, a volatile essential oil component. Two approaches were used: eugenol-loaded conventional liposomes were prepared and then coated with chitosan (referred to as chitosan-coated liposomes or chitosomes), blank empty chitosomes were prepared and then eugenol was added to join the structures (referred to as preformed chitosomes). Eugenol-loaded liposomes and -chitosomes were characterized and compared in terms of size, eugenol encapsulation efficiency (EE), eugenol loading rate (LR), and phospholipid and cholesterol incorporation rates (IR). Compared to conventional liposomes, the presence of chitosan coating layer increased significantly the mean particle size in a concentration dependent manner. Increasing the chitosan molecular weight led to an increase in cholesterol incorporation in liposomes. High EE of eugenol was obtained in all formulations (above 68.8%). However, both phospholipid and eugenol incorporation rates decreased in chitosomes. All chitosomal formulations enhanced the antioxidant activity of eugenol compared to the uncoated ones and maintained the eugenol encapsulation after 2 months of storage at 4 °C. The retention efficiency (RE) of eugenol into preformed blank conventional liposomes and chitosomes was assessed using the dialysis technique. After 21 days, the RE of eugenol reached 41, 45.5 and 80%, respectively in preformed liposomes and preformed chitosomes with low and high molecular weight. The results have demonstrated the incorporation of eugenol into both preformed systems, with the ability of chitosan to enhance its incorporation, especially with the highest molecular weight.

O-ATRP synthesized poly(β-pinene) blended with chitosan for antimicrobial and antioxidant bio-based films production

Antioxidant and antimicrobial activities are important characteristics of active film packaging designed to extend food preservation. In this study, functional bio-based films were produced using different concentrations of antioxidant poly(β-pinene) bio-oligomer synthesized via organocatalyzed atom transfer radical polymerization (O-ATRP) and blended with chitosan of different molecular weights. The structural, mechanical, thermal, solubility, antioxidant, and antimicrobial properties of the films were investigated. The poly(β-pinene)-chitosan blends presented significant pores and irregularities with the increase of poly(β-pinene) concentration over 30%. Chitosan molecular weight did not show any important influence in the physical properties of the blends. Poly(β-pinene) load decreased the materials' tensile strength and melting temperature, exhibiting a plasticizing effect on chitosan chains. The antioxidant and antimicrobial activities of the films were improved by poly(β-pinene) incorporation and mainly depended on its concentration. Therefore, the incorporation of poly(β-pinene) in chitosan films can be an alternative for active packaging production.

Extraction and Physicochemical Characterization of Chitosan from Pink Shrimp (Parapenaeus longirostris) Shell Wastes

This study aimed to evaluate the extract of chitosan obtained from pink shrimp (Parapenaeus longirostris) shell wastes in Balıkesir, the Marmara Sea in Turkey, and to characterize its quality. The physicochemical properties of biopolymer chitosan such as moisture content, solubility, degree of deacetylation (DD), molecular weight (MW), particle size, bulk density, pH, water-binding capacity (WBC), fat-binding capacity (FBC), and color attributes were examined. The obtained chitosan was characterized by Fourier transform infrared spektrofotometer (FT-IR), Dynamic light scattering (DLS), and Thermogravimetric measurements (TG/DTA/DTG). Results indicated that the yield and moisture content of chitosan was 18.82% and 3.62%, respectively. DD was 81.50% while solubility was 86.79%. MW of chitosan was found to be 310 kDa. The presence of the amino group was confirmed from the FT-IR spectra of the synthesized chitosan. Thermogravimetric measurements showed that chitosan had low thermal stability. SEM analysis revealed that the surface morphologies of chitosan consisted of relatively smooth surface and nanofiber structures. Based on the physicochemical characteristics obtained in the present study, pink shrimp could be a potential source to produce high-quality chitosan for industrial applications.

Magnetic Nanocomposites Containing Low and Medium-Molecular Weight Chitosan for Dye Adsorption: Hydrophilic Property Versus Functional Groups

Azo dye removal from polluted water is vital from a sustainable viewpoint. In this study, we investigated the influence of chitosan molecular weight on the adsorption of basic blue 41. Nanocomposite (NC(M)) was prepared using magnetite nanoparticles modified by amino-silica, medium-molecular weight chitosan, diethylenetriaminepentaacetic acid and graphene oxide. FT-IR, XRD, FESEM, TEM, EDX, elemental mapping, TGA/DTG, VSM and N2 adsorption/desorption isotherm were applied to characterize NC(M). Its effectiveness for the dye adsorption was compared with the adsorbent having low-molecular weight chitosan (NC(L)) (Asadabadi 2021). In this regard, the effect of initial pH, temperature and adsorbent concentration on the dye removal was investigated by Central Composite Design. The maximum percentage of dye removal was 31% for NC(M) at optimum conditions. An increase in the monomer number of chitosan caused to increase in the contact angle and decrease in the hydrophilic property of NC(M). Thus, it had a very low dye adsorption. However, NC(L) led to dye removal of 95%. It was proposed that NC(L) adsorbed dye by coulumbic attraction, π-stacking interactions and H-bonding. The NC(L) kinetics data were satisfactorily fitted by the modified pseudo-n-order model. About 30 min necessitated reaching the equilibrium and the rate-limiting steps changed from the film diffusion to intra-particle diffusion as time passed. The modified Langmuir–Freundlich isotherm was the best model to reproduce equilibrium data and the maximum adsorption capacity was equal to 55.87 mg·g−1. Besides, NC(L) was recovered seven times without dramatic changes in its adsorption efficiency.Graphic Abstract

Lung targeted electrosprayed chitosan nanocomposite microparticles boost the cytotoxic activity of magnolol

Large scale production of therapeutic nanoparticles (NPs) is still challenging. Herein, we report a facile single step electrospray process for the production of a nanocarrier platform made of hybridized chitosan (CS)/ polyvinyl alcohol (PVA) matrix. The method was adapted to achieve the lowest NPs size for carrying and delivering a hydrophobic anti-cancer drug, magnolol (Mag). To improve the inhalation properties of the optimized NPs formulation, the spray drying method was adopted to generate Mag loaded nano embedded-in-microparticles (Mag-NEM). The impact of the characteristics of CS and PVA blended solutions with and without Mag on the developed systems was investigated. The viscosity of the polymers solution played a major role on the size of electrosprayed NPs. NPs could only be obtained at CS:PVA ratio 7:3 and 8:2 for low molecular weight CS and at only 8:2 ratio for the medium molecular weight. Mag-NPs scoring 415.7 nm with a high drug encapsulation efficiency of 95.5% ±2.5 were successfully prepared at 0.1 mL/h flow rate, 15 cm tip to collector distance and 25 kV applied voltage. Optimized Mag-NEM exhibited good aerosolization properties with effective inhalation index of 64.69% and showed a two-fold decrease in IC50 when challenged against lung cancer cells A549.

Sclerotium oryzae biocontrol in flooded rice fields with floating microcarrier technology: The effect of chitosan molecular weight.

Biocontrol strategies are of significant concern for their application in crops. Various green practices have been designed, but almost all of them had delivery constraints. In particular, to design biocontrol strategies against Sclerotium oryzae in flooded rice fields, the active agent should be retained on the plant leaves by spreading application, nevertheless the direct application onto the water produces the biocontrol agent dilution. An effective delivery model was needed. This work aimed to evaluate the effects of chitosan molecular weight on the formation of positively charged Pseudomonas fluorescens-chitosan complex as a floating microcarrier against Sclerotium oryzae. To this end, three different sizes of chitosan [molecular weights (MWs) 20 000, 250 000, and 1 250 000 g mol-1 ] at different pH values (4, 6, and 7) were tested. The electrostatic interaction was analyzed through ζ-potential measurement. An adjustment of the experimental values was carried out for making predictions. The bacteria antifungal activity into the carrier with different chitosan MWs was analyzed. Our results suggest that it is possible to form a bacteria-chitosan complex with a net positive charge under condition that improve bacteria incorporation to the microcarrier technology without harming bacteria viability and antifungal activity. Thus, high chitosan MW (1250 000 g mol-1 ) at pH6 is preferable for microcarrier technology. Our findings provide relevant information about bacteria-chitosan interaction and may be useful in biocontrol programs that involved these two components as well as situations in which bacteria adsorption to an anionic carrier or anionic surface is desirable.

Toxicity of chitosan derivatives to Varroa destructor (Anderson and Trueman) and their effects on immune gene expression in honey bees

Varroasisis caused by Varroa destrucor (Anderson and Trueman) is considered the most dangerous honey bee disease. V. destructor mites parasitize both brood and adults, causing considerable losses to the colony population. The control of Varroa mites is highly dependent on the application of synthetic acaricides, however, acaricide resistance can develop. To eliminate the risk of Varroa mite resistance and to reduce residues in hive products, organic-based substances for Varroa mite control are being applied. In the present study, the acaricidal activity of N-alkyl and O-acyl chitosan derivatives against Varroa mites and their side effects on honey bees have been evaluated. Chitosan has been extracted from the corpses of honey bees. The yield, degree of deacetylation, and molecular weight of chitosan from the chitin of honey bee corpses were determined as 89%, 90%, and 20 kDa, respectively. Varroa mite mortalities were observed between 6.28-84.38% and 0.00-90.47% by N-alkyl and O-acyl chitosan derivatives, respectively. The best derivatives against Varroa mite were N-(3-phenylbutyl)chitosan (NAC-5) and O-(heptanoyl)chitosan (OAC-4). The results showed that different lethal concentrations of NAC-5 and OAC-4 had side effects against honey bees less than 26%. No significant difference was found between honey bee mortalities at 24, 48, and 72 hours post-treatment, while mortalities significantly differed between 4, and 24 h post-treatment. Immune gene expression in honey bees exposed to a lethal concentration of NAC-5and OAC-4 showed that the expressions of AmHym, AmBask, and AmSpz were significantly lower compared with those of control honey bees.

Sub-100-micron calcium-alginate microspheres: Preparation by nitrogen flow focusing, dependence of spherical shape on gas streams and a drug carrier using acetaminophen as a model drug

We developed a miniature gas-liquid coaxial flow device using glass capillaries, aiming to produce sub-100-μm Ca-alginate microspheres. Depending on collecting distance and the flow rates of nitrogen gas and alginate solution, however, Ca-alginate microparticles of different shapes were obtained. Spherical, monodisperse microparticles (microspheres) could only be obtained at certain gas flow rates and within a corresponding range of collecting distance. The result suggests that, for particles of this size, the gas flow rate and collecting distance are crucial for the formation of the spherical shape. We evaluated, as an example of its applications, the microsphere as a drug carrier using acetaminophen as a model drug. Large (~150 μm) and small (~70 μm) drug-loaded microspheres were prepared using two respective devices. Specifically, the drug-loaded microspheres were complexed with chitosan of different molecular weights. The dependence of in vitro drug release on the microsphere size and the chitosan molecular weight was examined. Chemical compounds studied in this articleAlginic acid sodium salt (PubChem CID: 5102882); Chitosan (PubChem CID: 71853); Calcium chloride (PubChem CID: 5284359); Sodium chloride (PubChem CID: 5234); Acetaminophen (PubChem CID: 1983); Polydimethylsiloxane (PubChem CID: 24771); n-Octadecyltrimethoxysilane (PubChem CID: 76486).

Electrophoretically deposited high molecular weight chitosan/bioactive glass composite coatings on WE43 magnesium alloy

Abstract Mg-based materials are good candidates for biodegradable bone regeneration implants due to their favorable mechanical properties and an excellent compatibility with human bone. However, too high corrosion/degradation rate in body fluids still limits their applicability. Coatings based on chitosan (CS) and bioactive glass (BG) particles fabricated by electrophoretic deposition (EPD) on Dulbecco's Modified Eagle Medium (DMEM) pre-treated magnesium alloys have promising potential to suppress the substrate corrosion and additionally to incorporate bioactivity. However, the impact of processing parameters or type of coating components on the long-term substrate corrosion behavior and cell response have not been investigated previously. In this study, two types of composite coatings based on a high molecular weight CS (Mw 340–360 kDa, DDA ≥ 95%) and embedded particles: solid BG (2 μm) and a mixture of BG and mesoporous bioactive glass nanoparticles (MBGN, 100–300 nm with mesopores 2.3–5.6 nm) were fabricated by EPD on DMEM pre-treated WE43 magnesium alloy. It was found that partial replacement of BG particles with MBGN (ratio 3:1) in the composite coating increases the water contact angle, surface roughness and induces a positive cell response. Although the acidic CS-based solutions and applied EPD conditions may decrease the stability of the temporary barrier formed during the DMEM pre-treatment on WE43 substrate therewith slightly increasing its corrosion sensitivity, the composite coating with a mixture of different sizes of particles (BG, MBGN) is a promising candidate for bone regeneration applications.

Development of Covalent Chitosan-Polyethylenimine Derivatives as Gene Delivery Vehicle: Synthesis, Characterization, and Evaluation.

There is an increasing interest in cationic polymers as important constituents of non-viral gene delivery vectors. In the present study, we developed a versatile synthetic route for the production of covalent polymeric conjugates consisting of water-soluble depolymerized chitosan (dCS; MW 6–9 kDa) and low molecular weight polyethylenimine (PEI; 2.5 kDa linear, 1.8 kDa branched). dCS-PEI derivatives were evaluated based on their physicochemical properties, including purity, covalent bonding, solubility in aqueous media, ability for DNA condensation, and colloidal stability of the resulting polyplexes. They were complexed with non-integrating DNA vectors coding for reporter genes by simple admixing and assessed in vitro using liver-derived HuH-7 cells for their transfection efficiency and cytotoxicity. Using a rational screening cascade, a lead compound was selected (dCS-Suc-LPEI-14) displaying the best balance of biocompatibility, cytotoxicity, and transfection efficiency. Scale-up and in vivo evaluation in wild-type mice allowed for a direct comparison with a commercially available non-viral delivery vector (in vivo-jetPEI). Hepatic expression of the reporter gene luciferase resulted in liver-specific bioluminescence, upon intrabiliary infusion of the chitosan-based polyplexes, which exceeded the signal of the in vivo jetPEI reference formulation by a factor of 10. We conclude that the novel chitosan-derivative dCS-Suc-LPEI-14 shows promise and potential as an efficient polymeric conjugate for non-viral in vivo gene therapy.

Corn Starch‐Chitosan Proportion Affects Biodegradable Film Performance for Food Packaging Purposes

AbstractThis work proposes an advance towards the scaling of biodegradable films based on corn starch and chitosan, considering the relevant film properties that condition their use for food packaging and their economic feasibility. The influence of corn starch: chitosan (CS:CH) proportion and chitosan molecular weight used in the formulation is also studied. Chitosan (CH) addition improves film forming dispersions (FFDs) stability stored under refrigerated conditions and enhances the film UV barrier properties and elongation at break, however material costs are higher. Films with higher starch content exhibited higher elastic modulus and tensile strength. Water vapor barrier, heat‐sealing capacity, and sealing resistance also increase with the corn starch (CS) proportion in film formulation. Taking into consideration the chitosan type used, the polymer‐plasticiser and polymer‐solvent interactions prevail and led to the development of more flexible materials in film formulations with low molecular weight chitosan (LMW‐CH). Meanwhile, polymer‐polymer interactions also became relevant in those obtained with MMW‐CH leading to resistant films. The obtained results indicate that composite films could be used in food packaging design, with those formulated with 75% CS and 25% medium molecular weight chitosan (MMW‐CH) being a good option considering both the film's properties as well as its economical feasibility.

Antifungal effect of chitosan of different molecular weight against Colletotrichum alatae under in vitro conditions

Antifungal effect of chitosan of different molecular weight against Colletotrichum alatae under in vitro conditions

Chitosan nanoparticles for enhancing drugs and cosmetic components penetration through the skin

Chitosan nanoparticles (CT NPs) have attractive biomedical applications due to their unique properties. This present research aimed at development of chitosan nanoparticles to be used as skin delivery systems for cosmetic components and drugs and to track their penetration behaviour through pig skin. CT NPs were prepared by ionic gelation technique using sodium tripolyphosphate (TPP) and Acacia as crosslinkers. The particle sizes of NPs appeared to be dependent on the molecular weight of chitosan and concentration of both chitosan and crosslinkers. CT NPs were positively charged as demonstrated by their Zeta potential values. The formation of the nanoparticles was confirmed by FTIR and DSC. Both SEM and TEM micrographs showed that both CT-Acacia and CT:TPP NPs were smooth, spherical in shape and are distributed uniformly with a size range of 200nm to 300 nm. The CT:TPP NPs retained an average of 98% of the added water over a 48-hour period. CT-Acacia NPs showed high moisture absorption but lower moisture retention capacity, which indicates their competency to entrap polar actives in cosmetics and release the encapsulated actives in low polarity skin conditions. The cytotoxicity studies using MTT assay showed that CT NPs made using TPP or Acacia crosslinkers were similarly non-toxic to the human dermal fibroblast cells. Cellular uptake study of NPs observed using live-cell imaging microscopy, proving the great cellular internalisation of CT:TPP NPs and CT-Acacia NPs. Confocal laser scanning microscopy revealed that CT NPs of particle size 530nm containing fluorescein sodium salt as a marker were able to penetrate through the pig skin and gather in the dermis layer. These results show that CT NPs have the ability to deliver the actives and cosmetic components through the skin and to be used as cosmetics and dermal drug delivery system.

Physicochemical characteristics of chitosan from swimming crab (Portunus trituberculatus) shells prepared by subcritical water pretreatment

The physicochemical properties of chitosan obtained from the shells of swimming crab (Portunus trituberculatus) and prepared via subcritical water pretreatment were examined. At the deacetylation temperature of 90 °C, the yield, ash content, and molecular weight of chitosan in the shells prepared via subcritical water pretreatment were 12.2%, 0.6%, and 1187.2 kDa, respectively. These values were lower than those of shells prepared via sodium hydroxide pretreatment. At the deacetylation temperature of 120 °C, a similar trend was observed in chitosan molecular weight, but differences in chitosan yield and ash content were not remarkable. At the same deacetylation temperature, the structures of chitosan prepared via sodium hydroxide and subcritical water pretreatments were not substantially different. However, the compactness and thermal stability of chitosan prepared via sodium hydroxide pretreatment was lower than those of chitosan prepared via subcritical water pretreatment. Compared with the chitosan prepared by sodium hydroxide pretreatment, the chitosan prepared by subcritical water pretreatment was easier to use in preparing oligosaccharides, including (GlcN)2, via enzymatic hydrolysis with chitosanase. Results suggested that subcritical water pretreatment can be potentially used for the pretreatment of crustacean shells. The residues obtained via this method can be utilized to prepare chitosan.

The effect of chitosan molecular weight on CO2-triggered switching between emulsification and demulsification

The role of molecular weight as a key physical property of macromolecules in determining the CO2-triggered switching characteristics of responsive emulsions prepared using CO2-switchable macromolecules has not been studied and is the focus of the current study. In this work, CO2-switchable chitosan of four different molecular weights is used to investigate the effect of molecular weight on CO2-triggered switching of CO2-responsive emulsions. The molecular weight of chitosan is shown to have an opposite effect on emulsification and demulsification by the CO2 trigger. Before bubbling of CO2, chitosan of higher molecular weight forms a more stable three-dimensional network structure in the continuous phase of oil-in-water (O/W) emulsions, which leads to the formation of a more stable emulsion. After bubbling of CO2, the chitosan of higher molecular weight makes the continuous phase more viscous, which leads to an incomplete demulsification as compared with the chitosan of lower molecular weight. Experimental evidence from the measurement of conductivity, interfacial tension and rheological properties is provided to support the proposed mechanism. This work is of great significance in guiding the selection of desirable CO2-switchable polymers for switchable emulsions of desired switching characteristics.

Pretreatment with different molecular weight chitosans encourages drought tolerance in rice (Oryza sativa L.) seedling

Drought is a critical environmental constraint limiting plant growth and productivity. Chitosan has been utilized as a potential biostimulant and proven to be effective against drought stress in many plant species. The objective of this study was to determine the effects of pretreatment with different molecular weight (MW) chitosans on some physiological characteristics of rice seedlings under drought stress. Rice seedlings were treated with low (50-190 kDa), medium (190-310 kDa) and high (310-375 kDa) MW chitosans by seed priming and foliar spray. The seedlings were subjected to drought by withholding water for four days. The relative water content (RWC) was reduced from 93% in the control plants to 74% in the droughted plants. The results revealed that treating with chitosan, especially with low MW chitosan, promoted root growth under drought stress. All chitosan treatments led to higher relative water content and photosynthetic pigment under drought condition. Pretreatment with chitosan also induced sugar accumulation, and treating with low MW chitosan significantly increased starch accumulation under drought stress. In addition, chitosan treatments alleviated the effects caused by drought stress as represented by the decreases in electrolyte leakage, malondialdehyde (MDA) as well as hydrogen peroxide (H2O2), corresponding with the increases in activities of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX) activity.

High- and low-molecular-weight chitosan act as adjuvants during single-dose influenza A virus protein vaccination through distinct mechanisms.

The investigation of new adjuvants is essential for the development of efficacious vaccines. Chitosan (CS), a derivative of chitin, has been shown to act as an adjuvant, improving vaccine‐induced immune responses. However, the effect of CS molecular weight (MW) on this adjuvanticity has not been investigated, despite MW having been shown to impact CS biological properties. Here, two MW variants of CS were investigated for their ability to enhance vaccine‐elicited immune responses in vitro and in vivo, using a single‐dose influenza A virus (IAV) protein vaccine model. Both low‐molecular‐weight (LMW) and high‐molecular‐weight (HMW) CS‐induced interferon regulatory factor pathway signaling, antigen‐presenting cell activation, and cytokine messenger RNA (mRNA) production, with LMW inducing higher mRNA levels at 24 h and HMW elevating mRNA responses at 48 h. LMW and HMW CS also induced adaptive immune responses after vaccination, indicated by enhanced immunoglobulin G production in mice receiving LMW CS and increased CD4 interleukin 4 (IL‐4) and IL‐2 production in mice receiving HMW CS. Importantly, both LMW and HMW CS adjuvantation reduced morbidity following homologous IAV challenge. Taken together, these results support that LMW and HMW CS can act as adjuvants, although this protection may be mediated through distinct mechanisms based on CS MW.

Evaluation of Chitosan Nanomaterials in the Treatment of Helicobacter pylori Mediated Gastric Diseases

We assessed the effect of chitosan on Helicobacter pylori (HPY) in vitro to provide an experimental basis for the clinical application of chitosan in the treatment of gastric diseases. Here, the method of hole drilling was used to detect the bacteriostatic effect of different concentrations and pH values of chitosan on the standard bacterial strain Sydney strain I (SSI) and two strains of HPY isolated from patients. The bacteriostatic test was used to explore the effect of different molecular weights of chitosan and metal ions on the antibacterial effect of chitosan. The effect of chitosan showed no significant difference among three HPY strains (p < 0.05); moreover, in the range of pH 5.5-8.5, the antibacterial effect of chitosan increased with decrease in pH value (p < 0.01). A significant difference in the antibacterial effect of chitosan was observed at different concentrations (p < 0.01), reaching a peak at 40 g/mL. The molecular weight of chitosan was within 400 kb. With increasing molecular weight, the antibacterial activity of chitosan increased initially and then decreased. The molecular weight of 0.200 kb demonstrated the strongest anti-HPY effect, with the antibacterial effect observed for up to 134 h. Metal ions such as NaCl and MgCl₂ affected the anti-HPY effect of chitosan; with increasing concentration, the antibacterial percentage decreased.