Fabrication and antimicrobial properties of novel meropenem-honey encapsulated chitosan nanoparticles against multiresistant and biofilm-forming Staphylococcus aureus as a new antimicrobial agent.

BACKGROUND: Honey exhibits a broad spectrum of antibacterial activity against Gram-positive and Gram-negative bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) ones. Chitosan (Cs) is a mucoadhesive polymer that also has antibacterial properties. Special attention has been paid to the design of polymeric nanoparticles (NPs) as new nano drug delivery systems to overcome bacterial resistance and its problems. OBJECTIVES: The aim of the present study is to synthesize Cs-meropenem NPs with/without honey as an antibiofilm and antibacterial agent to inhibit Staphylococcus aureus. METHODS: This study synthesized meropenem and honey-loaded Cs nanogels and subsequently characterized them by Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), and DLS-zeta potential. Using the broth microdilution and crystal violet assays, the antibacterial and antibiofilm activity of meropenem and honey-loaded Cs nanogel, free meropenem, free honey, and free Cs NPs were investigated in vitro against MRSA strains. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) was also used to test the cytotoxicity of several Cs-NPs compound against the HEK-293 regular cell line. RESULTS: The average size of meropenem and honey-Cs-NPs was reported to be 119.885 nm, and encapsulation efficiency was 88.33 ± 0.97 with stability up to 60 days at 4°C. The NPs showed enhanced antibiofilm efficacy against S. aureus at sub-minimum inhibitory concentrations. Additionally, the cytotoxicity of meropenem and honey-encapsulated Cs against the HEK-293 normal cell line was insignificant. CONCLUSIONS: Our findings suggested that meropenem and honey-Cs-NPs might be potential antibacterial and antibiofilm materials.

Aspirin/amoxicillin loaded chitosan microparticles and polydopamine modified titanium implants to combat infections and promote osteogenesis.

It is known that titanium (Ti) implant surfaces exhibit poor antibacterial properties and osteogenesis. In this study, chitosan particles loaded with aspirin, amoxicillin or aspirin + amoxicillin were synthesized and coated onto implant surfaces. In addition to analysing the surface characteristics of the modified Ti surfaces, the effects of the modified Ti surfaces on the adhesion and viability of rat bone marrow-derived stem cells (rBMSCs) were evaluated. The metabolic activities of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) biofilms on the modified Ti surfaces were also measured in vitro. Moreover, S. aureus was tested for its antibacterial effect by coating it in vivo. Using water as the droplet medium, the contact angles of the modified Ti surfaces increased from 44.12 ± 1.75° to 58.37 ± 4.15°. In comparison to those of the other groups tested, significant increases in rBMSC adhesion and proliferation were observed in the presence of aspirin + amoxicillin-loaded microspheres, whereas a significant reduction in the metabolic level of biofilms was observed in the presence of aspirin + amoxicillin-loaded microspheres both in vitro and in vivo. Aspirin and amoxicillin could be used in combination to coat implant surfaces to mitigate bacterial activities and promote osteogenesis.

Antibacterial effects of chitosan-based hydrogels containing Trachyspermum ammi essential oil on pathogens isolated from dogs with otitis externa.

BACKGROUND: Growing antibiotic resistance has made treating otitis externa (OE) increasingly challenging. On the other hand, local antimicrobial treatments, especially those that combine essential oils (EOs) with nanoparticles, tend to be preferred over systemic ones. It was investigated whether Ajwain (Trachyspermum ammi) EO, combined with chitosan nanoparticles modified by cholesterol, could inhibit the growth of bacterial pathogens isolated from OE cases in dogs. In total, 57 dogs with clinical signs of OE were examined and bacteriologically tested. Hydrogels of Chitosan were synthesized by self-assembly and investigated. EO was extracted (Clevenger machine), and its ingredients were checked (GC-MS analysis) and encapsulated in chitosan-cholesterol nanoparticles. Disc-diffusion and broth Micro-dilution (MIC and MBC) examined its antimicrobial and therapeutic properties. RESULTS: Staphylococcus pseudintermedius (49.3%) was the most common bacteria isolated from OE cases, followed by Pseudomonas aeruginosa (14.7%), Escherichia coli (13.3%), Streptococcus canis (9.3%), Corynebacterium auriscanis (6.7%), Klebsiella pneumoniae (2.7%), Proteus mirabilis (2.7%), and Bacillus cereus (1.3%). The investigation into the antimicrobial properties of Ajwain EO encapsulated in chitosan nanoparticles revealed that it exhibited a more pronounced antimicrobial effect against the pathogens responsible for OE. CONCLUSIONS: Using chitosan nanoparticles encapsulated with EO presents an effective treatment approach for dogs with OE that conventional antimicrobial treatments have not cured. This approach not only enhances antibacterial effects but also reduces the required dosage of antimicrobials, potentially preventing the emergence of antimicrobial resistance.

The scar-reducing effect of a novel chitosan gel: an in vivo study.

OBJECTIVE: Scar tissue formation, as a normal part of wound healing, initiates in the proliferation phase, continues after the remodelling phase, and may cause an unpleasant appearance or disruption in normal functioning. This study investigated the effects of a topical gel on acute wound healing and reducing scars in a rat model. METHOD: ChitoScar (ChitoTech Company, Iran), a commercial scar-reducing gel based on chitosan, was analysed for antibacterial and antiviral activity through a quantitative suspension test. Its cytotoxic effect was investigated, and then irritation and delayed-type hypersensitivity tests were carried out on rabbits through direct application of the gel. Furthermore, the effect of the chitosan-based gel on wound healing and scar tissue formation was studied in rats with an acute wound in two groups: the treatment group (topical application of the chitosan-based gel); and the control group (without treatment). Histopathological examination was carried out based on the inflammatory cells, collagen fibre, keratinocytes and fibroblasts. RESULTS: Analysis revealed that the chitosan-based gel had no cytotoxicity and caused no erythema, oedema, local or other systemic adverse response. Wound healing occurred earlier in the treatment group, which was a result of a significant increase in re-epithelialisation, angiogenesis, fibroblast population and collagen fibre thickness (p<0.05). In the treatment group, wounds healed completely after 21 days and scars totally disappeared after 28 days, while in the control group, wound healing remained incomplete with distinct scar tissue. CONCLUSION: The results demonstrated the positive effect of the chitosan-based gel on the duration and quality of the wound healing process, as well as minimising the scar tissue formation in this in vivo study.

Antibiofilm activity of polyethylene glycol-quercetin nanoparticles-loaded gelatin-N,O-carboxymethyl chitosan composite nanogels against Staphylococcus epidermidis.

BACKGROUND: Biofilms, such as those from Staphylococcus epidermidis, are generally insensitive to traditional antimicrobial agents, making it difficult to inhibit their formation. Although quercetin has excellent antibiofilm effects, its clinical applications are limited by the lack of sustained and targeted release at the site of S. epidermidis infection. OBJECTIVES: Polyethylene glycol-quercetin nanoparticles (PQ-NPs)-loaded gelatin-N,O-carboxymethyl chitosan (N,O-CMCS) composite nanogels were prepared and assessed for the on-demand release potential for reducing S. epidermidis biofilm formation. METHODS: The formation mechanism, physicochemical characterization, and antibiofilm activity of PQ-nanogels against S. epidermidis were studied. RESULTS: Physicochemical characterization confirmed that PQ-nanogels had been prepared by the electrostatic interactions between gelatin and N,O-CMCS with sodium tripolyphosphate. The PQ-nanogels exhibited obvious pH and gelatinase-responsive to achieve on-demand release in the micro-environment (pH 5.5 and gelatinase) of S. epidermidis. In addition, PQ-nanogels had excellent antibiofilm activity, and the potential antibiofilm mechanism may enhance its antibiofilm activity by reducing its relative biofilm formation, surface hydrophobicity, exopolysaccharides production, and eDNA production. CONCLUSIONS: This study will guide the development of the dual responsiveness (pH and gelatinase) of nanogels to achieve on-demand release for reducing S. epidermidis biofilm formation.

The ameliorative role of Aloe vera-loaded chitosan nanoparticles on Staphylococcus aureus induced acute lung injury: Targeting TLR/NF-κB signaling pathways.

Background: Acute lung injury (ALI) is a severe condition distinguished by inflammation and impaired gas exchange in the lungs. Staphylococcus aureus, a common bacterium, can cause ALI through its virulence factors. Aloe vera is a medicinal plant that has been traditionally used to treat a variety of illnesses due to its anti-inflammatory properties. Chitosan nanoparticles are biocompatible and totally biodegradable materials that have shown potential in drug delivery systems. Aim: To explore the antibacterial activity of Aloe vera-loaded chitosan nanoparticles (AV-CS-NPs) against S. aureus in vitro and in vivo with advanced techniques. Methods: The antibacterial efficacy of AV-CS-NPs was evaluated through a broth microdilution assay. In addition, the impact of AV-CS-NPs on S. aureus-induced ALI in rats was examined by analyzing the expression of genes linked to inflammation, oxidative stress, and apoptosis. Furthermore, rat lung tissue was scanned histologically. The rats were divided into three groups: control, ALI, and treatment with AV-CS-NPs. Results: The AV-CS-NPs that were prepared exhibited clustered semispherical and spherical forms, having an average particle size of approximately 60 nm. These nanoparticles displayed a diverse structure with an uneven distribution of particle sizes. The maximum entrapment efficiency of 95.5% ± 1.25% was achieved. The obtained findings revealed that The minimum inhibitory concentration and minimum bactericidal concentration values were determined to be 5 and 10 ug/ml, respectively, indicating the potent bactericidal effect of the NPs. Also, S. aureus infected rats explored upregulation in the mRNA expression of TLR2 and TLR4 compared to healthy control groups. AV-CS-NP treatment reverses the case where there was repression in mRNA expression of TLR2 and TLR4 compared to S. aureus-treated rats. Conclusion: These NPs can serve as potential candidates for the development of alternative antimicrobial agents.

Artesunate-loaded thermosensitive chitosan hydrogel promotes osteogenesis of maxillary tooth extraction through regulating T lymphocytes in type 2 diabetic rats.

BACKGROUND: Type 2 diabetes mellitus (T2DM) causes severe bone loss after tooth extraction as a hyperglycemic environment causes aberrant bone homeostasis. Artesunate (ART) is known to possess anti-inflammation and osteogenic properties. However, its osteogenesis property in alveolar bone remains unclear. This study aimed to explore the osteogenic and immunoregulatory effects of artesunate-loaded thermosensitive chitosan hydrogel (ART-loaded TCH) on maxilla tooth extraction in T2DM rats. METHODS: T2DM rats were induced by a high-fat diet and streptozotocin. Different concentrations of ART-loaded TCH were applied in tooth extraction sockets. Bone loss and the expression of osteogenic regulatory factors (OPG, ALP, RANK) were evaluated. The immunoregulatory effects of ART-loaded TCH were observed through detecting the infiltration of T lymphocytes and their cytokines. The underlying mechanisms were explored. RESULTS: Results showed that the 150 mg/ml ART-loaded TCH group significantly ameliorated maxilla bone height and bone mineral density when compared with the T2DM group (p < 0.05). It also improved the expression of OPG, ALP, and RANK. Although the alteration of CD4+ T, CD8+ T, and CD4+:CD8+ T ratio has no significant difference among groups, the release of Th1 and Th2 in the 150 mg/ml ART-loaded TCH group has been significantly regulated than in the T2DM group (p < 0.05). Besides, ART-loaded TCH treatment inhibited the expression of p38 MAPK and ERK1 in T2DM maxilla. CONCLUSIONS: Therefore, the results indicated that 150 mg/ml ART-loaded TCH could be an effective method to prevent bone loss in T2DM tooth extraction rats by modulating the immunoregulation of Th1 and Th2 and the MAPK signaling pathway.

Chitosan nanoparticles improve the effectivity of miltefosine against Acanthamoeba.

BACKGROUND: Acanthamoeba keratitis (AK) is a corneal sight-threatening infection caused by the free-living amoebae of the genus Acanthamoeba. Early and appropriate treatment significantly impacts visual outcomes. Mucoadhesive polymers such as chitosan are a potential strategy to prolong the residence time and bioavailability of the encapsulated drugs in the cornea. Regarding the recent administration of miltefosine (MF) for treating resistant AK, in the present study, we synthesized miltefosine-loaded chitosan nanoparticles (MF-CS-NPs) and evaluated them against Acanthamoeba. METHODOLOGY/PRINCIPAL FINDINGS: Chitosan nanoparticles (CNPs) were prepared using the ionic gelation method with negatively charged tripolyphosphate (TPP). The zeta-potential (ZP) and the particle size of MF-CS-NPs were 21.8±3.2 mV and 46.61±18.16 nm, respectively. The release profile of MF-CS-NPs indicated linearity with sustained drug release. The cytotoxicity of MF-CS-NPs on the Vero cell line was 2.67 and 1.64 times lower than free MF at 24 and 48 hours. This formulation exhibited no hemolytic activity in vitro and ocular irritation in rabbit eyes. The IC50 of MF-CS-NPs showed a significant reduction by 2.06 and 1.69-fold in trophozoites at 24 and 48 hours compared to free MF. Also, the MF-CS-NPs IC50 in the cysts form was slightly decreased by 1.26 and 1.21-fold at 24 and 48 hours compared to free MF. CONCLUSIONS: The MF-CS-NPs were more effective against the trophozoites and cysts than free MF. The nano-chitosan formulation was more effective on trophozoites than the cysts form. MF-CS-NPs reduced toxicity and improved the amoebicidal effect of MF. Nano-chitosan could be an ideal carrier that decreases the cytotoxicity of miltefosine. Further analysis in animal settings is needed to evaluate this nano-formulation for clinical ocular drug delivery.

Succinylated chitosan derivative restore HUVEC cells function damaged by TNF-α and high glucose in vitro and enhanced wound healing.

The inflammation of chronic wounds plays a key hindering role in the wound healing process. Slowing down the inflammatory response is significant for the repair of chronic wounds. Studies have revealed that succinate can inactivate gastrin D (GSDMD) and prevent cell pyroptosis. Chitosan has anti-inflammatory properties and is commonly used as wound healing material. Therefore, we used succinic anhydride to modify chitosan and found that N-succinylated chitosan (NSC) was more effective in inhibiting inflammation. The results showed that the stimulation of TNF-α and high glucose induces overexpression of capase-1 and TNF-α in human umbilical vein endothelial cells (HUVEC), and down-expression of CD31. However, the expression of capase-1 and TNF-α decreased, while the expression of CD31, VEGF and IL-10 was up-regulated significantly in dysfunctional HUVEC cells after treated by NSC. Moreover, NSC can speed wound healing, histological examination results showed that wounds treated with NSC exhibited faster epithelial tissue regeneration and thicker collagen deposition. Overall, this study results suggested that NSC has the function of restoring the physiological functions of dysfunctional HUVEC cells induced by high glucose and TNF-α, and can accelerate wound healing, indicating that NSC has good potential to be applied in inflammatory chronic wounds such as diabetic foot.

Fast skin healing chitosan/PEO hydrogels: In vitro and in vivo studies.

Due to its outstanding qualities, particularly when it takes the shape of hydrogels, chitosan is a well-known biological macromolecule with many applications. When chitosan hydrogels are modified with other polymers, the desirable function as skin regeneration hydrogels is compromised; nevertheless, the mechanical properties can be improved, which is crucial for commercialization. In this study, for the first time, bimetallic zinc silver metal-organic frameworks (ZAg MOF) loaded with ascorbic acid were added to chitosan/polyethylene oxide (PEO) based interpenetrating polymer network (IPN) hydrogels that were crosslinked with biotin to improve their antimicrobial activity, mechanical characteristics, and sustainable treatment of wounds. Significant changes in the microstructure, hydrophilicity level, and mechanical properties were noticed. Ascorbic acid release patterns were upregulated in an acidic environment pH (5.5) that mimics the initial wound pH. Impressive cell viability (98 %), antimicrobial properties, and almost full skin healing in a short time were achieved for the non-replaceable chitosan/PEO developed hydrogels. Enhancing the wound healing of the treated animals using the prepared CS/PEO hydrogel dressing was found to be a result of the inhibition of dermal inflammation via decreasing IL-1ß, suppressing ECM degradation (MMP9), stimulating proliferation through upregulation of TGF-ß and increasing ECM synthesis as it elevates collagen 1 and α-SMA contents. The findings support the implementation of developed hydrogels as antimicrobial hydrogels dressing for fast skin regeneration.

Trinitroglycerin-loaded chitosan nanogels: Shedding light on cytotoxicity, antioxidativity, and antibacterial activities.

AIM AND BACKGROUND: Trinitroglycerin (TNG) is a remarkable NO-releasing agent. Here, we synthesized TNG based on chitosan Nanogels (Ngs) for ameliorating complications associated with high-dose TNG administration. METHOD: TNG-Ngs fabricated through ionic-gelation technique. Fourier-transformed infrared (FT-IR), zeta-potential, dynamic light scattering (DLS), and electron microscopy techniques evaluated the physicochemical properties of TNG-Ngs. MTT was used to assess the biocompatibility of TNG-Ngs, as the antioxidative properties were determined via lactate dehydrogenase (LDH), reactive oxygen species (ROS), and lipid peroxide (LPO) assays. The antibacterial activity was evaluated against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococci (VRE). RESULTS: Physicochemical characterization reveals that TNG-Ngs with size diameter (96.2 ± 29 nm), polydispersity index (PDI, 0.732), and negative zeta potential (-1.1 mv) were fabricated. The encapsulation efficacy (EE) and loading capacity (LC) were obtained at 71.1 % and 2.3 %, respectively, with no considerable effect on particle size and morphology. The cytotoxicity assay demonstrated that HepG2 cells exposed to TNG-Ngs showed relative cell viability (RCV) of >80 % for 70 µg/ml compared to the TNG-free drug at the same concentration (P < 0.05). TNG-Ngs showed significant differences with the TNG-free drug for LDH, LPO, and ROS formation at the same concentration (P < 0.001). The antibacterial activity of the TNG-Ngs against S. aureus, E. coli, VRE, and MRSA was higher than the TNG-free drug and Ngs (P < 0.05). CONCLUSION: TNG-Ngs with enhanced antibacterial and antioxidative activity and no obvious cytotoxicity might be afforded as novel nanoformulation for promoting NO-dependent diseases.

Biogenic crocetin-crosslinked chitosan nanoparticles with high stability and drug loading for efficient radioprotection.

The risk of radiation exposure increases with the development of nuclear energy and technology, and radiation protection receives more and more attention from public health and safety. However, the numerous adverse effects and low drug utilization limit the practical applications of radioprotective agents. In this study, we developed a biogenic crocetin-crosslinked chitosan nanoparticle with high stability and drug loading for efficient radioprotection. In detail, the nanoparticles were prepared using the natural antioxidant crocetin as a cross-linking reagent in amidation reactions of chitosan and mPEG-COOH. The nanoparticles exhibit a quick scavenging ability for common reactive oxygen species and reactive nitrogen in vitro. Meanwhile, cellular experiments demonstrate the good biocompatibility of the nanoparticles and the alleviation of radiation damage by scavenging reactive oxygen species, reducing apoptosis, and inhibiting DNA damage, etc. Importantly, the nanoparticles are effective in mitigating oxidative damage in major organs and maintaining peripheral blood cell content. In addition, they perform better radioprotective properties than free drug due to the significant extension of the blood half-life of crocetin in vivo from 10 min to 5 h. This work proposes a drug-crosslinking strategy for the design of a highly efficient radioprotective agent, which exhibits a promising prospect in the fields of nuclear emergency and public health.

Chitosan synergizes with bismuth-based metal-organic frameworks to construct double S-type heterojunctions for enhancing photocatalytic antimicrobial activity.

In recent years, photocatalytic technology has been introduced to develop a new kind antimicrobial agents fighting antibiotic abusing and related drug resistance. The efforts have focused on non-precious metal photocatalysts along with green additives. In the present work, a novel bis-S heterojunctions based on the coupling of polysaccharide (CS) and bismuth-based MOF (CAU-17) s synthesized through a two-step method involving amidation reaction under mild conditions. The as prepared photocatalyst literally extended the light response to the near-infrared region. Owing to its double S-type heterostructure, the lifetime of the photocarriers is significantly prolonged and the redox capacity are enhanced. As a result, the as prepared photocatalyst indicated inhibition up to 99.9 % under 20 min of light exposure against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria as well as drug-resistant bacteria (MRSA). The outstanding photocatalytic performance is attributed to the effective charge separation and migration due to the unique double S heterostructure. Such a double S heterostructure was confirmed through transient photocurrent response, electrochemical impedance spectroscopy tests and electron spin resonance measurements. The present work provides a basis for the simple synthesis of high-performance heterojunction photocatalytic inhibitors, which extends the application of CAU-17 in environmental disinfection and wastewater purification.

One-pot co-crystallized hexanal-loaded ZIF-8/quaternized chitosan film for temperature-responsive ethylene inhibition and climacteric fruit preservation.

Controlling ethylene production and microbial infection are key factors to prolong the shelf life of climacteric fruit. Herein, a nanocomposite film, hexanal-loaded ZIF-8/CS (HZCF) with "nano-barrier" structure, was developed by a one-pot co-crystallized of ZIF-8 in situ growth on quaternized chitosan (CS) and encapsulation of hexanal into ZIF-8 via microporous adsorption. The resultant film realized the temperature responsive release of hexanal via the steric hindrance and hierarchical pore structure as "nano-barrier", which can inhibit ethylene production in climacteric fruit on demand. Based on this, the maximum ethylene inhibition rate of HZCF was up to 52.6 %. Meanwhile, the film exhibits excellent antibacterial, mechanical, UV resistance and water retention properties, by virtue of the functional synergy between ZIF-8 and CS. Contributed to the multifunctional features, HZCF prolonged the shelf life of banana and mango for at least 16 days, which is 8 days longer than that of control fruit. More strikingly, HZCF is washable and biodegradable, which is expected to replace non-degradable plastic film. Thus, this study provides a convenient novel approach to simplify the encapsulation of active molecule on metal-organic frameworks (MOFs), develops a packaging material for high-efficient freshness preservation, and helps to alleviate the survival crisis caused by food waste.

Recombinant human collagen I/carboxymethyl chitosan hydrogel loaded with long-term released hUCMSCs derived exosomes promotes skin wound repair.

BACKGROUND: Stem cell exosomes are beneficial in accelerating wound repair. However, the therapeutic function is limited due to its rapid clearance in vivo. To improve the functionality of exosomes in cutaneous wound healing, a novel hydrogel was designed and fabricated by recombinant human collagen I and carboxymethyl chitosan loaded with exosomes derived from human umbilical cord mesenchymal stem cells (hUCMSCs), named as the rhCol I/CMC-Exos hydrogel. METHODS: Exosomes were extracted from hUCMSCs and were characterizated by TEM (Transmission Electron Microscopy), and biomarker detection. The rhCol I hydrogel, rhCol I/carboxymethyl chitosan (rhCol I/CMC) hydrogel and the rhCol I/CMC-Exos hydrogel composites were cross-linked by genipin. These materials were assessed and compared for their physical characteristics, including cross-sectional morphology, porosity, pore distribution, and hydrophilicity. Cell biocompatibility on biomaterials was investigated using scanning electron microscopy and CFDA staining, as well as assessed in vivo through histological examination of major organs in mice. Effects of the hydrogel composite on wound healing were further evaluated by using the full-thickness skin defect mice model. RESULTS: Successful extraction of hUCMSCs-derived exosomes was confirmed by TEM，Western Blotting and flow cytometry. The synthesized rhCol I/CMC-Exos hydrogel composite exhibited cytocompatibility and promoted cell growth in vitro. The rhCol I/CMC-Exos hydrogel showed sustained release of exosomes. In the mice full skin-defects model, the rhCol I/CMC-Exos-treated group showed superior wound healing efficiency, with 15 % faster wound closure compared to controls. Histological examinations revealed thicker dermis formation and more balanced collagen deposition in wounds treated with rhCol I/CMC-Exos hydrogel. Mechanistically, the application of rhCol I/CMC-Exos hydrogel increased fibroblasts proliferation, alleviated inflammation responses as well as promoted angiogenesis, thereby was beneficial in promoting skin wound healing and regeneration. CONCLUSION: Our study, for the first time, introduced recombinant human Collagen I in fabricating a novel hydrogel loaded with hUCMSCs-derived exosomes, which effectively promoted skin wound closure and regeneration, demonstrating a great potential in severe skin wound healing treatment.

Enhanced antibacterial properties of polyvinyl alcohol/starch/chitosan films with NiO-CuO nanoparticles for food packaging.

Packaging is very important to maintain the quality of food and prevent the growth of microbes. Therefore, the use of food packaging with antimicrobial properties protects the food from the growth of microorganisms. In this study, antibacterial nanocomposite films of polyvinyl alcohol/starch/chitosan (PVA/ST/CS) together with nickel oxide-copper oxide nanoparticles (NiO-CuONPs) are prepared for food packaging. NiO-CuONPs were synthesized by the co-precipitation method, and structural characterization of nanoparticles (NPs) was carried out by XRD, FTIR, and SEM techniques. Composites of PVA/ST/CS, containing different percentages of NPs, were prepared by casting and characterized by FTIR and FESEM. The mechanical properties, diffusion barrier, and thermal stability were determined. The nanoparticles have a round structure with an average size of 6.7 ± 1.2 nm. The cross-section of PVA/ST/CS film is dense, uniform, and without cracks. In the mechanical tests, the addition of NPs up to 1% improved the mechanical properties (TS = 31.94 MPa), while 2% of NPs lowered TS to 14.76 MPa. The fibroblast cells toxicity and the films antibacterial activity were also examined. The films displayed stronger antibacterial effects against Gram-positive bacteria (Staphylococcus aureus) compared to Gram-negative bacteria (Escherichia coli). Furthermore, these films have no toxicity to fibroblast cells and the survival rate of these cells in contact with the films is more than 84%. Therefore, this film is recommended for food packaging due to its excellent mechanical and barrier properties, good antibacterial activity, and non-toxicity.

Green synthesis of chitosan nanoparticles using tea extract and its antimicrobial activity against economically important phytopathogens of rice.

The aim of the present work is to biosynthesize Chitosan nanoparticles (CTNp) using tea (Camellia sinensis) extract, with potent antimicrobial properties towards phytopathogens of rice. Preliminary chemical analysis of the extract showed that they contain carbohydrate as major compound and uronic acid indicating the nature of acidic polysaccharide. The structure of the isolated polysaccharide was analyzed through FTIR and 1H NMR. The CTNp was prepared by the addition of isolated tea polysaccharides to chitosan solution. The structure and size of the CTNp was determined through FTIR and DLS analyses. The surface morphology and size of the CTNp was analysed by SEM and HRTEM. The crystalinity nature of the synthesized nanoparticle was identified by XRD analysis. The CTNp exhibited the antimicrobial properties against the most devastating pathogens of rice viz., Pyricularia grisea, Xanthomonas oryzae under in vitro condition. CTNp also suppressed the blast and blight disease of rice under the detached leaf assay. These results suggest that the biosynthesized CTNp can be used to control the most devastating pathogens of rice.

Enhanced antibacterial activity of porous chitosan-based hydrogels crosslinked with gelatin and metal ions.

Addressing the increasing drug resistance in pathogenic microbes, a significant threat to public health, calls for the development of innovative antibacterial agents with versatile capabilities. To enhance the antimicrobial activity of non-toxic biomaterials in this regard, this study focuses on novel, cost-effective chitosan (CS)-based hydrogels, crosslinked using gelatin (GEL), formaldehyde, and metallic salts (Ag+, Cu2+, and Zn2+). These hydrogels are formed by mixing CS and GEL with formaldehyde, creating iminium ion crosslinks with metallic salts without hazardous crosslinkers. Characterization techniques like FTIR, XRD, FESEM, EDX, and rheological tests were employed. FTIR analysis showed metal ions binding to amino and hydroxyl groups on CS, enhancing hydrogelation. FESEM revealed that freeze-dried hydrogels possess a crosslinked, porous structure influenced by various metal ions. Antibacterial testing against gram-negative and gram-positive bacteria demonstrated significant bacterial growth inhibition. CS-based hydrogels containing metal ions showed reduced MIC and MBC values against Staphylococcus aureus (0.5, 8, 16 µg/mL) and Escherichia coli (1, 16, 8 µg/mL) for CS-g-GEL-Ag+, CS-g-GEL-Cu2+, and CS-g-GEL-Zn2+. MTT assay results confirmed high biocompatibility (84.27%, 85.24%, 84.96% viability at 10 µg/mL) for CS-based hydrogels towards HFF-1 cells over 48 h. Therefore, due to their non-toxic nature, these CS hydrogels are promising for antibacterial applications.

Multilayer Electrospun Scaffolds of Opposite-Charged Chitosans.

Chitosan (CS) is a polysaccharide obtainable by the deacetylation of chitin, which is highly available in nature and is consequently low-cost. Chitosan is already used in the biomedical field (e.g., guides for nerve reconstruction) and has been proposed as a biomaterial for tissue regeneration in different body districts, including bone tissue. The interest in chitosan as a biomaterial stems from its ease of functionalization due to the presence of reactive groups, its antibacterial properties, its ease of processing to obtain porous matrices, and its inherent similarity to polysaccharides that constitute the human extracellular matrix, such as hyaluronic acid (HA). Here, chitosan was made to react with succinic anhydride to develop a negatively charged chitosan (SCS) that better mimics HA. FT-IR and NMR analyses confirmed the presence of the carboxylic groups in the modified polymer. Four different electrospun matrices were prepared: CS, SCS, a layer-by-layer matrix (LBL), and a matrix with both CS and SCS simultaneously electrospun (HYB). All the matrices containing SCS showed increased human osteoblast proliferation, mineralization, and gene expression, with the best results obtained with HYB compared to the control (CS). Moreover, the antibacterial potential of CS was preserved in all the SCS-containing matrices, and the pure SCS matrix demonstrated a significant reduction in bacterial proliferation of both S. aureus and E. coli.

Bio-formulated chitosan nanoparticles enhance disease resistance against rice blast by physiomorphic, transcriptional, and microbiome modulation of rice (Oryza sativa L.).

Rice blast disease (RBD) caused by Magnaporthe oryzae, threaten food security by cutting agricultural output. Nano agrochemicals are now perceived as sustainable, cost-effective alternatives to traditional pesticides. This study investigated bioformulation of moringa chitosan nanoparticles (M-CsNPs) and their mechanisms for suppressing RBD while minimizing toxic effects on the microenvironment. M-CsNPs, sized 46 nm with semi-spherical morphology, significantly suppressed pathogen growth, integrity, and colonization at 200 mg L-1in vitro. Greenhouse tests with foliar exposure to the same concentration resulted in a substantial 77.7 % reduction in RBD, enhancing antioxidant enzyme activity and plant health. Furthermore, M-CsNPs improved photosynthesis, gas exchange, and the nutritional profile of diseased rice plants. RNA-seq analysis highlighted upregulated defense-related genes in treated rice plants. Metagenomic study showcased reshaping of the rice microbiome, reducing Magnaporthe abundance by 93.5 %. Both healthy and diseased rice plants showed increased microbial diversity, particularly favoring specific beneficial species Thiobacillus, Nitrospira, Nocardioides, and Sphingomicrobium in the rhizosphere and Azonexus, Agarivorans, and Bradyrhizobium in the phyllosphere. This comprehensive study unravels the diverse mechanisms by which M-CsNPs interact with plants and pathogens, curbing M. oryzae damage, promoting plant growth, and modulating the rice microbiome. It underscores the significant potential for effective plant disease management.