Development of chitosan-sodium phytate nanoparticles as a potent antibacterial agent

Effect of cross-linking density on the rheological behavior of ultra-soft chitosan microgels at the oil-water interface

In this paper, microgels with uniform particle size were prepared by physically cross-linking the hydrophobically modified chitosan (h-CS) with sodium phytate (SP). The effects of cross-linking density on the interfacial adsorption kinetics, viscoelasticity, stress relaxation, and micorheological properties of the hydrophobically modified chitosan microgels (h-CSMs) at the oil-water interface were extensively investigated by the dilatational rheology, compressional rheology, and particle tracing microrheology. The results were correlated with the particle size, morphology, and elasticity of the microgels characterized by dynamic light scattering and atomic force microscopy. It was found that with the increase of cross-linking density, the h-CSMs changed from a polymer-like state to ultra-soft fussy spheres with higher elastic modulus. The compression isotherms demonstrated multi-stage increase caused by the interaction between the shells and that between the cores of the microgels successively. As the increase of cross-linking density, the h-CSMs diffused slower to the oil-water interface, but demonstrating faster permeation adsorption and rearrangement at the oil-water interface, finally forming interfacial layers of higher viscoelastic modulus due to the core-core interaction. Both the initial tension relaxation and the microgel rearrangement after interface expansion became faster as the microgel elasticity increased. The interfacial microrheology demonstrated dynamic caging effect caused by neighboring microgels. This article provides a more comprehensive understanding of the behaviors of polysaccharide microgels at the oil-water interface.

Immunomodulatory activity of ovotransferrin-chlorogenic acid complexes enhanced by high-intensity ultrasound (HIU): A structure-function relationship study

This study investigated the impact of high-intensity ultrasound (HIU) treatment on the physiochemical, conformational, and immunomodulatory activity of the OVT-CA complex, emphasizing the structure-function relationship. HIU treatment reduced particle size, improved dispersion, and increased electronegativity of the complex. It facilitated binding between OVT and CA, achieving a maximum degree of 45.22 mg/g CA grafting and reducing interaction time from 2 h to 15 min. HIU-induced cavitation and shear promoted the exposure of -SH and unfolding of OVT, leading to increased surface hydrophobicity of the complex and transformation of its structure from β-sheet to α-helix. Additionally, CA binds to OVT in the C-lobe region, and HIU treatment modulates the intermolecular forces governing the complex formation, particularly by reinforcing hydrogen bonding, hydrophobic interactions, and introducing electrostatic interactions. Furthermore, HIU treatment increased the immunomodulatory activity of the complex, which was attributed to complex structural changes facilitating enhanced cell membrane affinity, antigen recognition, and B-cell epitope availability. Hierarchical cluster and Pearson correlation analysis confirmed that HIU treatment duration had a greater impact than power on both the structure and activity of the complex, and an optimal HIU treatment duration within 30 min was found to be crucial for activity enhancement. Moreover, structural changes, including ζ-potential, particle size/turbidity, and surface hydrophobicity, were closely correlated with immunomodulatory activity. This study highlights the potential application of HIU in developing protein-polyphenol immunomodulatory agents for public health and food nutrition.

Chitosan Phytate Nanoparticles: A Synergistic Strategy for Effective Dental Caries Prevention

Dental caries is a widespread oral disease that poses a significant medical challenge. Traditional caries prevention methods, primarily the application of fluoride, often fall short in effectively destroying biofilms and preventing enamel demineralization, thereby providing limited efficacy in halting the progression of caries over time. To address this issue, we have developed a green and cost-effective synergistic strategy for the prevention of dental caries. By combining natural sodium phytate and chitosan, we have created chitosan-sodium phytate nanoparticles that offer both the antimicrobial properties of chitosan and the enamel demineralization-inhibiting capabilities of sodium phytate. In an ex vivo biofilm model of human teeth, we found that these nanoparticles effectively prevent biofilm buildup and acid damage to the mineralized tissue. Additionally, topical treatment of dental caries in rodent models has shown that these nanoparticles effectively suppress disease progression without negatively impacting oral microbiota diversity or causing harm to the gingival-mucosal tissues, unlike traditional prevention methods.

Sequential removal of phosphate and copper(II) ions using sustainable chitosan biosorbent

Although adsorbents are good candidates for removing phosphorus and heavy metals from wastewater, the use of biosorbents for the sequential treatment of phosphorus and copper has not yet been studied. Porous chitosan (CS)-based biosorbents (CGBs) were developed to adsorb phytic acid (PA), a major form of organic phosphate. This first adsorbate (PA) further served as an additional ligand (P-type ligand) for the CGBs (N-type ligand) to form a complex with the second adsorbate (copper). After the adsorption of PA (the first adsorbate), the spent CGBs were recycled and used as a new adsorbent to adsorb Cu(II) ions (the second adsorbate), which was expected to have a dual coordination effect through P, N-ligand complexation with copper. The interactions and complexation between CS, PA and Cu(II) ions on the PA-adsorbed CGBs (PACGBs) were investigated by performing FTIR, XPS, XRD, and SEM-EDS analyses. The PACGBs exhibited fast and enhanced adsorption of Cu(II) ions, owing to the synergistic effect of the amino groups of CS (the original ligand, N-type) and the phosphate groups of PA (an additional ligand, P-type) on the adsorption of Cu(II) ions. This is the first time that sequential removal of phosphorus and heavy metals by biosorbents has been performed using biosorbents.

Guanidinylated bioactive chitosan-based injectable hydrogels with pro-angiogenic and mechanical properties for accelerated wound closure

Wound healing is a complex process involving the concerted action of many genes and signaling pathways, with angiogenesis being crucial for expediting wound closure. Dressings that possess pro-angiogenic properties are increasingly recognized as attractive candidates for wound care. Drawing inspiration from the active closure of wounds in embryos, we have developed a thermo-responsive hydrogel with mechanoactive properties, combining vascular regeneration and skin wound contraction to accelerate healing. The significant improvement in vascular reconstruction is attributed to the synergistic effect of arginine and deferoxamine (DFO) released from the hydrogels. Additionally, the contraction force of the hydrogel actively promotes skin closure in wounds. Remarkably, groups treated with hydroxybutyl chitosan methacrylate combined with arginine (HBC_m_Arg/DFO) exhibited increased vascularization, and greater wound maturity, leading to enhanced healing. These results highlight the synergistic impact of pro-angiogenic and mechanical properties of the HBC_m_Arg/DFO hydrogel in accelerating wound healing in rats.

Metronidazole loaded chitosan-phytic acid polyelectrolyte complex nanoparticles as mucoadhesive vaginal delivery system for bacterial vaginosis

Bacterial vaginosis (BV) is a recurring infection that is difficult to treat due to the limited bioavailability of antimicrobials. In this study, Metronidazole (MTZ)-loaded chitosan nanoparticles (MCSNP) were synthesized employing phytic acid (PA) as a crosslinking agent for treating bacterial vaginosis. The prepared MCSNPs were characterized for size, shape, surface charge, compatibility, cytotoxicity, biofilm inhibition, and in-vitro/in-vivo antimicrobial activities. Morphological examination revealed that nanoparticles generated from 0.535 % w/v chitosan and 0.112 % w/v PA were non-spherical, discontinuous, and irregular, with zeta potential ranging from 25.00 ± 0.45 to 39 ± 0.7. The results of DSC and XRD demonstrated no change in the physical state of the drug in the finished formulation. The optimized formulation demonstrates a cumulative drug release of about 98 ± 1.5 % within 8 h. Antimicrobial studies demonstrated that the optimized formulation had enhanced efficacy against acid-adapted BV pathogens, with a MIC value of 0.9 ± 0.1 μg/mL. Compared to the MTZ alone, the in-vivo antibacterial results of in the case of developed nanoparticles showed a four-fold reduction in bacterial count in female Swiss albino mice. Based on the experimental findings, it was concluded that MCSNPs, due to their excellent physiochemical and antibacterial properties, could serve as a potential topical alternative for treating BV.

Responsive and biocompatible chitosan-phytate microparticles with various morphology for antibacterial activity based on gas-shearing microfluidics

Chitosan microparticles are frequently used for the encapsulation of ingredients, owing to their pH-responsive, renewable, biocompatible and antimicrobial properties. Herein, pH-responsive antibacterial encapsulation carriers in chitosan-phytate (CS-PA) microparticles with various morphologies were prepared by gas-shearing microfluidics. Microparticles sizes were tuned by gas flow rate in production, and the CS and PA concentration significantly dominated the morphology of microparticles. Additionally, microparticles exhibit great storage stability, lyophilizing rehydration performance, pH-responsive behavior, as well as antibacterial and biocompatible effect, indicating that CS-PA microparticles are expected to become an ideal carrier for the actives encapsulation in pharmaceutical, food and cosmetic industries.

Construction of nano slow-release systems for antibacterial active substances and its applications: A comprehensive review

At present, nano-carrier materials with antibacterial activity are of great significance. Due to the widespread resistance of many pathogenic microorganisms, it has seriously threatened human health. The natural antimicrobial substances extracted from fruits and vegetables can significantly improve their stability combined with nano-carrier materials. The resistance of pathogenic microorganisms will be substantially reduced, greatly enhancing the effect of active antimicrobial substances. Nanotechnology has excellent research prospects in the food industry, antibacterial preservation, food additives, food packaging, and other fields. This paper introduces nano-carrier materials and preparation techniques for loading and encapsulating active antibacterial substances in detail by constructing a nano-release system for active antibacterial substances. The antibacterial effect can be achieved by protecting them from adverse external conditions and destroying the membrane of pathogenic microorganisms. The mechanism of the slow release of the bacteriostatic active substance is also described. The mechanism of carrier loading and release is mainly through non-covalent forces between the bacteriostatic active substance and the carrier material, such as hydrogen bonding, π-π stacking, van der Waals forces, electrostatic interactions, etc., as well as the loading and adsorption of the bacteriostatic active substance by the chemical assembly. Finally, its wide application in food and medicine is introduced. It is hoped to provide a theoretical basis and technical support for the efficient utilization and product development of bacteriostatic active substances.

Antimicrobial effect of sorbic acid-loaded chitosan/tripolyphosphate nanoparticles on Pseudomonas aeruginosa

Sorbic acid-loaded chitosan/tripolyphosphate nanoparticles (SANs) have previously been shown to exert both antibacterial and antioxidant effects on Chinese sausage. In this study, the minimum inhibitory concentrations (MICs) of SANs against two Pseudomonas aeruginosa strains were determined. The blank control group (BC) served as the negative control, while the chitosan/tripolyphosphate nanoparticles (CTNs) group and free sorbic acid (SA) group served as the positive controls. Tests conducted under five different pH conditions (5/6/7/8/9) revealed that the SANs exhibited a good bacteriostatic effect against P. aeruginosa. Variations in the metabolism, cell membrane or cell wall integrity, and morphology of P. aeruginosa were measured to evaluate the effects of SANs on their intracellular and extracellular components. The MIC of SANs for the two P. aeruginosa strains was determined to be 150 μg/mL. SANs delayed the growth of P. aeruginosa and severely damaged both its inner and outer cell membranes. The heteromorphism of the bacteria as observed by field emission scanning electron microscopy (FESEM), verified the aforementioned results. The results showed SANs could effectively inhibit the growth of P. aeruginosa and exert antibacterial ability in a wider range of acid-base environments. This study broadens the application of SANs in food processing and provides experimental basis.

Fabrication and application of chitosan-based biomass composites with fire safety, water treatment and antibacterial properties

In this work, a biomass composite material (CS@NC@PA-Na) was prepared from chitosan (CS), nano-cellulose (NC) and sodium phytate (PA-Na). The prepared products were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrometry (XPS) and X-ray diffraction (XRD). The fire/water safety and antimicrobial properties of the CS@NC@PA-Na were fully studied. The results indicated CS@NC@PA-Na (50 mg) could effectively reduce the concentration of methyl orange by 85 % under 30 min adsorption. Meanwhile, only 5 wt% CS@NC@PA-Na could increase the limiting oxygen index (LOI) value of epoxy resin composite from 24.5 to 30.1 %, and decrease the peak heat/smoke release rate by 29.5 and 33.3 %, respectively. Moreover, CS@NC@PA-Na also exhibited excellent antibacterial effect. This work provides an efficient, feasible and eco-friendly route for large-scale production of multi-functional CS-based biomass materials that could be used in the fields of fire safety and environmental conservation.

Corrigendum: Applications of chitosan and its derivatives in skin and soft tissue diseases

[This corrects the article DOI: 10.3389/fbioe.2022.894667.].

Applications of Chitosan and its Derivatives in Skin and Soft Tissue Diseases

Chitosan and its derivatives are bioactive molecules that have recently been used in various fields, especially in the medical field. The antibacterial, antitumor, and immunomodulatory properties of chitosan have been extensively studied. Chitosan can be used as a drug-delivery carrier in the form of hydrogels, sponges, microspheres, nanoparticles, and thin films to treat diseases, especially those of the skin and soft tissue such as injuries and lesions of the skin, muscles, blood vessels, and nerves. Chitosan can prevent and also treat soft tissue diseases by exerting diverse biological effects such as antibacterial, antitumor, antioxidant, and tissue regeneration effects. Owing to its antitumor properties, chitosan can be used as a targeted therapy to treat soft tissue tumors. Moreover, owing to its antibacterial and antioxidant properties, chitosan can be used in the prevention and treatment of soft tissue infections. Chitosan can stop the bleeding of open wounds by promoting platelet agglutination. It can also promote the regeneration of soft tissues such as the skin, muscles, and nerves. Drug-delivery carriers containing chitosan can be used as wound dressings to promote wound healing. This review summarizes the structure and biological characteristics of chitosan and its derivatives. The recent breakthroughs and future trends of chitosan and its derivatives in therapeutic effects and drug delivery functions including anti-infection, promotion of wound healing, tissue regeneration and anticancer on soft tissue diseases are elaborated.

Development of chitosan/tannic acid/corn starch multifunctional bilayer smart films as pH-responsive actuators and for fruit preservation

The design of intelligent films for pH-responsive actuators fully constructed from natural biopolymers remains challenging. This study used natural biopolymers to develop a new type of smart and multifunctional chitosan/tannic acid/corn starch (CHT/TA/CS) bilayer films, which can be used for pH-responsive actuators and fruit preservation. We studied the microstructural morphology, physicochemical, antioxidant, antimicrobial properties of the films. Compared with the CHT film, the water vapor permeability (WVP) values of the CHT/TA/CS bilayer films were reduced by 3.1 times, and the tensile strength was increased by 4.6 times. The CHT/TA/CS bilayer films also exhibited high 1,1-diphenyl-2-picrylhydrazyl (DPPH) (94.6%) and hydroxyl (OH) (97.5%) radical scavenging activity. The bilayer films had good antimicrobial activity. The CHT/TA/CS bilayer films exhibited different directional deformation behaviors in acid-base solutions and could be used as pH-responsive actuators. By changing the solution's pH, the bilayer films could grab and release heavy objects 21 times heavier than themselves. Furthermore, the CHT/TA/CS bilayer coating prolonged the bananas' storage time from three to six days, and its weight loss was reduced by 14%. The developed CHT/TA/CS bilayer films have potential application in degradable materials, soft robotics fields, and food packaging materials.

Crosslinkers for polysaccharides and proteins: Synthesis conditions, mechanisms, and crosslinking efficiency, a review

Polysaccharides and proteins are important macromolecules for developing hydrogels devoted to biomedical applications. Chemical hydrogels offer chemical, mechanical, and dimensional stability than physical hydrogels due to the chemical bonds among the chains mediated by crosslinkers. There are many crosslinkers to synthesize polysaccharides and proteins based on hydrogels. In this review, we revisited the crosslinking reaction mechanisms between synthetic or natural crosslinkers and polysaccharides or proteins. The selected synthetic crosslinkers were glutaraldehyde, carbodiimide, boric acid, sodium trimetaphosphate, N,N'-methylene bisacrylamide, and polycarboxylic acid, whereas the selected natural crosslinkers included transglutaminase, tyrosinase, horseradish peroxidase, laccase, sortase A, genipin, vanillin, tannic acid, and phytic acid. No less important are the reactions involving click chemistry and the macromolecular crosslinkers for polysaccharides and proteins. Literature examples of polysaccharides or proteins crosslinked by the different strategies were presented along with the corresponding highlights. The general mechanism involved in chemical crosslinking mediated by gamma and UV radiation was discussed, with particular attention to materials commonly used in digital light processing. The evaluation of crosslinking efficiency by gravimetric measurements, rheology, and spectroscopic techniques was presented. Finally, we presented the challenges and opportunities to create safe chemical hydrogels for biomedical applications.

Encapsulation of Curcumin in a Ternary Nanocomplex Prepared with Carboxymethyl Short Linear Glucan-Sodium-Caseinate-Pectin Via Electrostatic Interactions

This work chemically modified short linear glucan (SLG) by introducing a surface carboxymethyl group to obtain carboxymethylated SLG (CMSLG), then prepared CMSLG-based ternary nanocomplex particles based on electrostatic interactions with sodium-caseinate (NaCas) and pectin. These nanocomplex particles are homogeneous, generally exhibiting sizes of <200 nm with spherical shape and negative surface charge. In addition, the results showed the increase in both the mass ratio of CMSLG and NaCas and the synthesis temperature can improve the colloidal stability of nanocomplex particles when they are exposed to simulated gastrointestinal fluids containing digestive enzymes. Moreover, nanocomplex particles have an exceptional capability to encapsulate curcumin, and this encapsulation efficiency increased as the mass ratios of CMSLG and NaCas were increased. The study also investigated the antioxidant activity and in vitro release properties of curcumin encapsulated by nanocomplex particles and found that CMSLG/NaCas/pectin had improved higher ABTS radical scavenging capacity and allowed for the controlled, sustained release of curcumin in simulated gastrointestinal fluid within 6 hours. Thus, this study provides new insights into the design of a CMSLG-based ternary nanocomplex and its use as a potential oral delivery system for lipophilic bioactive compounds. PRACTICAL APPLICATION: Curcumin, as a sort of natural polyphenolic compound, has many physiologic functions such as anti-oxidation, anticancer, and prevention of Alzheimer's disease. However, the application of the curcumin has been limited by its poor water solubility and unstable physicochemical property. To solve this problem, the nanotechnology has been used to prepare the nano-delivery carriers for curcumin. This work prepared a ternary nanoparticle based on the carboxymethyl short linear glucan, sodium-caseinate, and pectin. The ternary nanoparticle can achieve a higher encapsulation efficiency for curcumin. In addition, the ternary nanoparticle can enhance the ABTS radical scavenging capacity and provided control and sustained release of curcumin in the simulated gastrointestinal fluid.

Preparation and applications of chitosan and cellulose composite materials

Chitosan is a natural fiber, chemically cellulose-like biopolymer, which is processed from chitin. Its use as a natural polymer is getting more attention because it is non-toxic, renewable, and biocompatible. However, its poor mechanical and thermal strength, particle size, and surface area restrict its industrial use. Consequently, to improve these properties, cellulose and/or inorganic nanoparticles have been used. This review discusses the recent progress of chitosan and cellulose composite materials, their preparation, and their applications in different industrial sectors. It also discusses the modification of chitosan and cellulose composite materials to allow their use on a large scale. Finally, the recent development of chitosan composite materials for drug delivery, food packaging, protective coatings, and wastewater treatment are discussed. The challenges and perspectives for future research are also considered. This review suggests that chitosan and cellulose nano-composite are promising, low-cost products for environmental remediation involving a simple production process.

Self-coacervation of carboxymethyl chitosan as a pH-responsive encapsulation and delivery strategy

Carboxymethyl chitosan (CMCS)-based complex coacervate has attracted much attention in drug oral delivery due to its pH-responsive property. As a unique ampholyte polymer, the self-coacervation of CMCS has great research potential. In this work, CMCS self-coacervates were prepared by adjusting the pH of the CMCS aqueous solution close to its isoelectric point. The Fourier-transformed infrared spectroscopy (FTIR) results revealed that electrostatic interactions, hydrogen bonding, and hydrophobic interactions were involved in the self-coacervation of CMCS. The obtained self-coacervates presented a dense surface structure, and were stable at a wide pH range of 3.0-6.0, and gradually dissolved under basic conditions. Although self-coacervation decreased the crystallinity and thermal stability of CMCS, the obtained coacervates showed excellent pH-responsive properties and ionic strength stability. We also investigated its potential in lactoferrin (LF) encapsulation and oral delivery. The CMCS self-coacervates exhibited a high encapsulation efficiency (EE) of 94.79 ± 0.49% and loading capacity (LC) of 26.29 ± 0.52% when the addition amount of LF was 2 mg. The simulated gastric digestion results demonstrated that CMCS self-coacervates could protect more than 80% of LF from hydrolysis and maintain the bioactivities of LF. Accordingly, the self-coacervation of CMCS could be used as a pH-responsive encapsulation and delivery strategy.

Polymorphism of chitosan-based networks stabilized by phytate investigated by molecular dynamics simulations

Chitosan can associate in the presence of polyphosphates into insoluble hydrogels capable of drug encapsulation and safe and efficient release. On the one hand, chitosan hydrogels were synthesized using the phytate anion as a crosslinking agent and were characterized by employing dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR). On the other hand, an effective chitosan-phytate model with atomistic details was created to examine the underlying physical crosslinking pattern, and the structure and dynamics of the chitosan-phytate complex were systematically investigated by using molecular dynamics (MD) simulations. To harbor the crosslinker potential for obtaining chitosan-based hydrogels, the impact of the phytate concentration and the functional groups of the chitosan on the reticulation process was addressed. The phytate association was determined by the phosphates' capacity for H-bonding to the amine and hydroxyl groups belonging to two consecutive glucosidic units. The physical crosslinking pattern was determined by the number of chitosan chains bound by one phytate anion and the phytate orientation relative to the glucopyranose neighbors. Cross-linking of two up to six chitosan chains mediated by a phytate anion represented favorable states, and the number distribution of cross-linked chains depended on the phytate concentration. The circular distribution of the cross-linkable phosphates regulated the nearly isotropic orientation of the chitosan chains and phytate at the junction, and the variety of topological crosslinking demonstrated the phytate ion's potential for developing chitosan-based hydrogels with improved structural attributes.

Innovative Polyelectrolyte Treatment to Flame-Retard Wood

Fire protection has been a major challenge in wood construction for many years, mainly due to the high flame spread risk associated with wood flooring. Wood fire-retardancy is framed by two main axes: coating and bulk impregnation. There is a growing need for economically and environmentally friendly alternatives. The study of polyelectrolyte complexes (PECs) for wood substrates is in its infancy, but PECs’ versatility and eco-friendly character are already recognized for fabric fire-retardancy fabrics. In this study, a new approach to PEC characterization is proposed. First, PECs, which consist of polyethyleneimine and sodium phytate, were chemically and thermally characterized to select the most promising systems. Then, yellow birch (Betula alleghaniensis Britt.) was surface-impregnated under reduced pressure with the two PECs identified as the best options. Overall, wood fire-retardancy was improved with a low weight gain of 2 wt.% without increasing water uptake.

Two Fascinating Polysaccharides: Chitosan and Starch. Some Prominent Characterizations for Applying as Eco-Friendly Food Packaging and Pollutant Remover in Aqueous Medium. Progress in Recent Years: A Review

The call to use biodegradable, eco-friendly materials is urgent. The use of biopolymers as a replacement for the classic petroleum-based materials is increasing. Chitosan and starch have been widely studied with this purpose: to be part of this replacement. The importance of proper physical characterization of these biopolymers is essential for the intended application. This review focuses on characterizations of chitosan and starch, approximately from 2017 to date, in one of their most-used applications: food packaging for chitosan and as an adsorbent agent of pollutants in aqueous medium for starch.

Chitosan-Based Nanocomposite Polymeric Membranes for Water Purification-A Review

During the past few years, researchers have focused their attention on developing innovative nanocomposite polymeric membranes with applications in water purification. Natural and synthetic polymers were considered, and it was proven that chitosan-based materials presented important features. This review presents an overview regarding diverse materials used in developing innovative chitosan-based nanocomposite polymeric membranes for water purification. The first part of the review presents a detailed introduction about chitosan, highlighting the fact that is a biocompatible, biodegradable, low-cost, nontoxic biopolymer, having unique structure and interesting properties, and also antibacterial and antioxidant activities, reasons for using it in water treatment applications. To use chitosan-based materials for developing nanocomposite polymeric membranes for wastewater purification applications must enhance their performance by using different materials. In the second part of the review, the performance's features will be presented as a consequence of adding different nanoparticles, also showing the effect that those nanoparticles could bring on other polymeric membranes. Among these features, pollutant's retention and enhancing thermo-mechanical properties will be mentioned. The focus of the third section of the review will illustrate chitosan-based nanocomposite as polymeric membranes for water purification. Over the last few years, researchers have demonstrated that adsorbent nanocomposite polymeric membranes are powerful, important, and potential instruments in separation or removal of pollutants, such as heavy metals, dyes, and other toxic compounds presented in water systems. Lastly, we conclude this review with a summary of the most important applications of chitosan-based nanocomposite polymeric membranes and their perspectives in water purification.

Recent Advances in Nanotechnology-Aided Materials in Combating Microbial Resistance and Functioning as Antibiotics Substitutes

The ongoing escalation of drug-resistant bacteria creates the leading challenges for human health. Current predictions show that deaths due to bacterial illness will be more in comparison to cancer in 2050. Irrational use of antibiotics, prolonged regimen and using as a prophylactic treatment for various infections are leading cause of microbial resistance. It is an emerging approach to introduce evolving nanomaterials (NMs) as a base of antibacterial therapy to overcome the bacterial resistance pattern. NMs can implement several bactericidal ways and turn into a challenge for bacteria to survive and develop resistance against NMs. All the pathways depend on the surface chemistry, shape, core material and size of NMs. Because of these reasons, NMs based stuff shows a critical role in advancing the treatment efficiency by interacting with the cellular system of bacteria and functioned as an antibiotic substitute. We divided this review into two sections. The first part highlights the development of microbial resistance to antibiotics and their mechanisms. The second section details the NMs mechanisms to combat antibiotic resistance. In short, we try to summarize the advances in NMs role to deal with microbial resistance and giving solution as antibiotics substitute.

Preparation and Synergistic Effect of Chitosan/Sodium Phytate/MgO Nanoparticle Fire-Retardant Coatings on Wood Substrate through Layer-By-Layer Self-Assembly

Fire-retardant chitosan/sodium phytate/MgO nanoparticle (CH/SP/nano-MgO) coatings were loaded on a wood substrate via electrostatic layer-by-layer self-assembly and characterized by scanning electron microscopy and energy-dispersive spectrometry. The flammability and thermal degradation of the original wood and wood samples treated with chitosan, chitosan/sodium phytate, chitosan/sodium phytate/MgO nanoparticles were studied by limiting oxygen index (LOI), exposure combustion experiments and thermogravimetric analysis (TGA), respectively. The CH/SP/nano-MgO coating served as an intumescent fire-retardant system that created a physical protection cover and exhibited the best fire retardant performance. The LOI value was 30.2% and required approximately 16–17 s to self-extinguish when exposed to air. The TGA curves also showed that char formation protected the wood from combustion.

Optimization of phytic acid-crosslinked chitosan microspheres for oral insulin delivery using response surface methodology

Although oral administration is favorable mode of insulin delivery, it is the most challenging route, owing to poor oral bioavailability. In this study, a chitosan (CS)-based insulin delivery system was developed by ionic crosslinking with phytic acid (PA). CS-PA microspheres were optimized with different crosslinking conditions of CS and PA using response surface methodology to retain insulin during preparation and gastric digestion. Furthermore, the in vitro release profile, morphological structure, cytotoxicity, and intestinal permeability of the optimized microspheres, and its hypoglycemic effect in diabetic rats were evaluated. Under optimal conditions, the entrapment efficiency was 97.1%, and 67.0% of insulin was retained in the microspheres after 2 h of gastric digestion followed by a sustained-release in intestinal fluid. Insulin was primarily distributed in the microsphere core with a monodisperse diameter of 663.3 μm. The microspheres increased the permeability of insulin across Caco-2/HT-29 monolayers by 1.6 times with negligible cytotoxicity. The microspheres had a relative pharmacological bioavailability of 10.6% and significantly reduced blood glucose levels with a long-lasting hypoglycemic effect after oral administration in diabetic rats. This study demonstrated that an optimized formulation of a simple ionic crosslinking system using CS and PA could facilitate efficient oral delivery of insulin.

Advances in Lipid and Metal Nanoparticles for Antimicrobial Peptide Delivery

Antimicrobial peptides (AMPs) have been described as excellent candidates to overcome antibiotic resistance. Frequently, AMPs exhibit a wide therapeutic window, with low cytotoxicity and broad-spectrum antimicrobial activity against a variety of pathogens. In addition, some AMPs are also able to modulate the immune response, decreasing potential harmful effects such as sepsis. Despite these benefits, only a few formulations have successfully reached clinics. A common flaw in the druggability of AMPs is their poor pharmacokinetics, common to several peptide drugs, as they may be degraded by a myriad of proteases inside the organism. The combination of AMPs with carrier nanoparticles to improve delivery may enhance their half-life, decreasing the dosage and thus, reducing production costs and eventual toxicity. Here, we present the most recent advances in lipid and metal nanodevices for AMP delivery, with a special focus on metal nanoparticles and liposome formulations.

Synthesis, Characterisation and Biological Evaluation of Ampicillin-Chitosan-Polyanion Nanoparticles Produced by Ionic Gelation and Polyelectrolyte Complexation Assisted by High-Intensity Sonication

Recently, one of the promising strategies to fight sensitive and resistant bacteria, and decrease the morbidity and mortality rates due to non-nosocomial infections, is to use antibiotic-loaded nanoparticles. In this study, ampicillin-loaded chitosan-polyanion nanoparticles were produced through the techniques of ionic gelation and polyelectrolyte complexation assisted by high-intensity sonication, using several crosslinking agents, including phytic acid (non-polymeric polyanion), sodium and potassium salts of poly(maleic acid-alt-ethylene) and poly(maleic acid-alt-octadecene) (polymeric polyanions). These nanoparticles were analysed and characterised in terms of particle size, polydispersity index, zeta potential and encapsulation efficiency. The stability of these nanosystems was carried out at temperatures of 4 and 40 °C, and the antimicrobial effect was determined by the broth microdilution method using sensitive and resistant Staphylococcus aureus strains. The results reveal that most of the nanosystems have sizes <220 nm, positive zeta potential values and a monodisperse population, except for the nanoparticles crosslinked with PAM-18 polyanions. The nanometric systems exhibited adequate stability preventing aggregation and revealed a two-fold increase in antimicrobial activity when compared with free ampicillin. This study demonstrates the potential application of synthesised nanoparticles in the field of medicine, especially for treating infections caused by pathogenic S. aureus strains.

Comparative study of antidiabetic, bactericidal, and antitumor activities of MEL@AgNPs, MEL@ZnONPs, and Ag-ZnO/MEL/GA nanocomposites prepared by using MEL and gum arabic

In this study, a variety of nanocomposites, namely, MEL@AgNPs, MEL@ZnONPs, and Ag-ZnO/MEL/GA were biosynthesized using MEL and gum arabic to serve in biomedical applications. The synthesized nanocomposites were examined using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and FTIR spectroscopy. The physicochemical properties and biomedical activities of the synthesized nanocomposites were investigated. The Ag-ZnO/MEL/GA nanocomposites showed greater antidiabetic activity against α-amylase and α-glucosidase, and higher antibacterial activity compared to MEL@AgNPs and MEL@ZnONPs. Furthermore, HepG2 cells were exposed to MEL@AgNPs, MEL@ZnONPs, and Ag-ZnO/MEL/GA nanocomposites for 24 h and their IC50 values were 63.25, 26.91 and 28.97 μg mL-1 (P < 0.05), respectively. According to this comparative study, it is apparent that the Ag-ZnO/MEL/GA nanocomposites have a great potential to serve as antitumor agents against HepG2, and antidiabetic and antibacterial agents.

Characterization of Cationic Modified Debranched Starch and Formation of Complex Nanoparticles with κ-Carrageenan and Low Methoxyl Pectin

The functional modifications of debranched starch (DBS) has been attracting the interest of researchers. This study marks the first time that DBS was modified by cationization through the use of (3-chloro-2-hydroxypropyl) trimethylammonium chloride with the introduction of cationic functional groups. The physicochemical properties and structural characteristics of cationized debranched starch (CDBS) were systematically assessed. The results demonstrate that the maximum degree of substitution (DS) value obtained was as high as 1.14, and the corresponding CDBS exhibited significantly higher zeta potential values: approximately +35 mV. The minimal inhibitory concentration values of the CDBS of DS 1.14 against Escherichia coli and Staphylococcus aureus were 6 and 8 mg mL^-1, respectively. In addition, nanoparticles were successfully prepared with a combination of CDBS and low methoxyl pectin (LMP) and a combination of CDBS and κ-carrageenan (CRG). The maximum encapsulation efficiency of nanoparticles for (-)-epigallocatechingallate can reach 87.8%.

pH-Sensitive Chitosan-Sodium Phytate Core-Shell Hollow Beads and Nanocapsules for the Encapsulation of Active Ingredients

The oral administration of nutraceuticals and vitamins is the most compliant route because of its minimal invasiveness, painlessness, ease of use, and cost effectiveness. To overcome the possible destruction and low availability induced by the harsh gastrointestinal environment, we use sodium phytate as a cross-linker to fabricate pH-sensitive core-shell chitosan hollow beads and nanocapsules through the ionic linking method for the controllable release of active ingredients. Texture profile analysis, transmission electron microscopy, dynamic light scattering, and scanning electron microscopy were used to characterize the morphologies and behaviors of the beads and nanocapsules. The size of the beads could be adjusted from 0.1 to 10 mm, and the diameter of the nanocapsules was 50-100 nm. The addition of pectin in sodium phytate remarkably increased the hardness of the chitosan beads. Nile blue A was used as a model active ingredient for loading into the chitosan beads with the maximum encapsulation efficiency (EE) and loading capacity of 96.07 ± 2.45% and 9.61 ± 0.29%, respectively. Polyphenols including catechin, epicatechin, epigallocatechin-3-gallate, and proanthocyanidin were successfully loaded into the chitosan nanocapsules with an EE of above 90%. The cumulative release of Nile blue A from the beads at pH 1.2 (after 2 h) and pH 6.8 (after 6 h) was less than 20% and more than 80%, respectively. Similarly, the cumulative release of polyphenols in the nanocapsules at pH 1.2 (after 2 h) and pH 6.8 (after 6 h) was less than 30% and more than 70%, respectively. In sum, chitosan-sodium phytate with and without pectin could form pH-responsive macro- and nanoscale carriers suitable for the encapsulation and controlled release of active ingredients.

Preparation and Characterization of Insulin-Loaded Zein/Carboxymethylated Short-Chain Amylose Complex Nanoparticles

In this work, we use antisolvent precipitation to prepare zein/carboxymethylated short-chain amylose (CSA) complex nanoparticles for insulin encapsulation, showing that insulin-loaded zein/CSA complex nanoparticles are homogeneous, generally exhibiting sizes of <200 nm with a narrow distribution (polydispersity index < 0.100), spherical shape, and strong negative charge (-40 mV). Fourier transform infrared spectroscopy analysis reveals that the formation of the above nanoparticles is mainly driven by hydrophobic, hydrogen-bonding, and electrostatic interactions between CSA, insulin, and zein. In comparison to zein nanoparticles, zein/CSA complex nanoparticles feature much higher insulin encapsulation efficiency (45.8 versus 90.5%, respectively) and are essentially nontoxic to Caco-2 cells. Thus, this work provides new insights into the design of drug delivery systems and is expected to inspire their further development.

Foliar Application of Cu Nanoparticles Modified the Content of Bioactive Compounds in Moringa oleifera Lam

Moringa oleifera Lam is a plant that has recently gained importance as a food because of its nutritional value and bioactive compound content and because practically all the organs are usable. The use of nanoparticles has appeared as an alternative to increase bioactive compounds in plants. The goal of this work was to determine if the application of copper nanoparticles would increase the content of bioactive compounds and antioxidant capacity in M. oleifera. Copper (Cu) nanoparticles were applied to the leaves at four different times throughout crop growth. The biocompounds were analyzed after the second, third, and fourth applications. The results show that application of Cu nanoparticles has a beneficial effect on the accumulation of bioactive compounds in M. oleifera leaves. In addition, the antioxidant capacity and carotenoid and chlorophyll contents in the leaves of M. oleifera increased after Cu nanoparticles application. The same effect was not observed in the fruit of M. oleifera. Here, the bioactive compound contents diminished. Therefore, the use of Cu nanoparticles can be an important alternative to improve the quality of this plant, particularly that of the leaves.

Salicylic acid loaded chitosan microparticles applied to lettuce seedlings: Recycling shrimp fishing industry waste

Shrimp fishing industry wastes are still a main problem with high environmental impact worldwide. In this study, chitosan with ultra-high molecular weight and deacetylation degree ≥85% was obtained from shrimp fishing industry waste from Argentinean Patagonia. Chitosan based microparticles capable to entrap salicylic acid, a phytohormone known to play major role in the regulation of plant defense response against various pathogens, were prepared using TPP as crosslinker. Unloaded microparticles and microparticles loading several salicylic acid amount were fully characterized exhibiting a size between 1.57 μm and 2.45 μm. Furthermore, a good PDI, entrappment efficiencies from 59% to 98% and salicylic acid sustained release over 24 h were achieved. Chitosan based microparticles were non toxic in most of the doses applied in lettuce seedlings. Instead, microparticles can positively modulate plant growth and have the potential to improve plant defense responses. In particular salicylic acid loaded microparticles effect was very promising for its application as activators of salicylic acid dependent plant defense responses in lettuce as a model of horticultural plant species.

Application of Light Scattering Techniques to Nanoparticle Characterization and Development

Over the years, the scientific importance of nanoparticles for biomedical applications has increased. The high stability and biocompatibility, together with the low toxicity of the nanoparticles developed lead to their use as targeted drug delivery systems, bioimaging systems, and biosensors. The wide range of nanoparticles size, from 10 nm to 1 μm, as well as their optical properties, allow them to be studied using microscopy and spectroscopy techniques. In order to be effectively used, the physicochemical properties of nanoparticle formulations need to be taken into account, namely, particle size, surface charge distribution, surface derivatization and/or loading capacity, and related interactions. These properties need to be optimized considering the final nanoparticle intended biodistribution and target. In this review, we cover light scattering based techniques, namely dynamic light scattering and zeta-potential, used for the physicochemical characterization of nanoparticles. Dynamic light scattering is used to measure nanoparticles size, but also to evaluate their stability over time in suspension, at different pH and temperature conditions. Zeta-potential is used to characterize nanoparticles surface charge, obtaining information about their stability and surface interaction with other molecules. In this review, we focus on nanoparticle characterization and application in infection, cancer and cardiovascular diseases.

Chitosan-Sodium Phytate Films with a Strong Water Barrier and Antimicrobial Properties Produced via One-Step-Consecutive-Stripping and Layer-by-Layer-Casting Technologies

The pursuit of sustainable functional materials requires the development of materials based on renewable resources and efficient fabrication methods. Here, we first fabricated chitosan-sodium phytate films via one-step-stripping and layer-by-layer-casting technologies. The proposed film-fabrication methods are general, facile, environmentally benign, cost-effective, and easy to scale up. The resultant one-step-stripped film was thin (9 ± 1 μm), soft, transparent, and strong, whereas the thickness of the layer-by-layer-cast film was 70 ± 3 μm. FTIR analysis of the films indicated the formation of interactions between the phosphoric groups in sodium phytate and the amino groups in chitosan. More importantly, the water-vapor-permeability values of the one-step-stripped and cast films were 4-5 orders of magnitude lower than chitosan films reported before. Layer-by-layer-cast films in particular exhibited high tensile strength (49.21 ± 1.12 MPa) and were more than three times stronger than other polyelectrolyte multilayer films. Both types of films remained stable in an acidic environment. Furthermore, the layer-by-layer-assembled films presented greater antimicrobial activity than the stripped films. The developed chitosan-sodium phytate films can enhance several biomedical and environmental applications, such as packaging, drug delivery, diagnostics, microfluidics, and biosensing.