Original method for synthesis of chitosan-based antimicrobial agent by quaternary ammonium grafting

Photochemical Strategies toward Precision Targeting against Multidrug-Resistant Bacterial Infections

Infectious diseases pose a serious threat and a substantial economic burden on global human and public health security, especially with the frequent emergence of multidrug-resistant (MDR) bacteria in clinical settings. In response to this urgent need, various photobased anti-infectious therapies have been reported lately. This Review explores and discusses several photochemical targeted antibacterial therapeutic strategies for addressing bacterial infections regardless of their antibiotic susceptibility. In contrast to conventional photobased therapies, these approaches facilitate precise targeting of pathogenic bacteria and/or infectious microenvironments, effectively minimizing toxicity to mammalian cells and surrounding healthy tissues. The highlighted therapies include photodynamic therapy, photocatalytic therapy, photothermal therapy, endogenous pigments-based photobleaching therapy, and polyphenols-based photo-oxidation therapy. This comprehensive exploration aims to offer updated information to facilitate the development of effective, convenient, safe, and alternative strategies to counter the growing threat of MDR bacteria in the future.

Effect of Chitosan and Hyperbranched Poly-L-Lysine Treatment on Quality of Cucumber (Cucumis sativus L.) during Storage

To enhance the storage time of cucumbers, this research investigated the impact of chitosan (CS) and hyperbranched poly-L-lysine (HBPL) on the quality and nutritional attributes of cucumbers when stored at a temperature of 25 °C. The results demonstrated that sensory evaluation scores for cucumbers treated with a CS-HBPL combination were significantly higher than the control (CK), CS, and HBPL groups. On the 18th day of storage, cucumbers in the CK group exhibited significant decay and softening; however, there was a decrease in hardness observed in the CS-HBPL group and no decay or noticeable sour taste was detected. Furthermore, compared to the CK group, treatment with CS-HBPL effectively delayed cucumber decay and weight loss rate while significantly inhibiting decreases in cucumber hardness and growth of surface microorganisms. Additionally, it substantially reduced losses of soluble protein content as well as vitamin C (Vc), reducing sugars, and total phenolic compounds within cucumbers, which were 4.7 mg/g, 4.7 mg/g, 0.94 mg/g, and 0.52 mg/kg, respectively. Moreover, compared to the CK group, combined treatment with CS-HBPL significantly inhibited malondialdehyde (MDA) accumulation and reducing relative electrolyte permeability within cucumbers, which were 1.45 μmol·g-1FW and 29.82%. Furthermore, it notably enhanced activities of superoxide dismutase (SOD) and catalase (CAT), while exerting a significant inhibitory effect on polyphenol oxidase (PPO). In summary, the combined CS-HBPL treatment successfully prolonged cucumber shelf life at room temperature, enabling new possibilities for extending cucumber shelf life.

Quaternary-ammonium chitosan, a promising packaging material in the food industry

Quaternary-ammonium chitosan (QAC) is a polysaccharide with good water solubility, bacteriostasis, and biocompatibility. QAC is obtained by methylating or grafting the quaternary-ammonium group of chitosan and is an important compound in the food industry. Various QAC-based complexes have been prepared using reversible intermolecular interactions, such as electrostatic interactions, hydrogen bonding, metal coordination, host-guest interactions, and covalent bonding interactions consisting of Schiff base bonding and dynamic chemical bond cross-linking. In the food industry, QAC is often used as a substrate in film or coating for food preservation and as a carrier for active substances to improve the encapsulation efficiency and storage stability of functional food ingredients. In this review, we have assimilated the latest information on QAC to facilitate further discussions and future research. Advancement in research on QAC would contribute toward technology acceleration and its increased contribution to the field of food technology.

Magnesium/gallic acid bioMOFs laden carbonized mushroom aerogel effectively heals biofilm-infected skin wounds

Biofilm-infected acute skin wounds are still one of the significant challenges that need to be solved urgently in wound healing. Herein, we reported a magnesium/gallic acid bio-MOFs laden carbonized mushroom aerogel (QMOFs-PCMA) combined with photothermal therapy for eradicating biofilms in skin wounds. The design of bioMOFs is mainly responsible for regulating immunity. In vitro, it exhibited ROS clearance and antioxidant ability. In vivo, it could regulate local immune responses from pro-inflammatory status to pro-regenerative status, resulting in decreased inflammatory cytokines expression and increased anti-inflammatory cytokines expression. The carbonized mushroom aerogel is mainly responsible for photothermal therapy (PTT), and the polydopamine and bioMOFs could enhance the photothermal conversion efficiency and stability of carbonized aerogels. The carbonized aerogel in combination with PTT could eradicate S. aureus biofilm in both in vitro and in vivo studies and clear E. coli biofilms in vitro studies. The biofilm clearance and improved inflammatory responses laid a good foundation for wound healing, resulting in the granulation tissue formation, re-epithelialization, and angiogenesis significantly enhanced in the QMOFs-PCMA + NIR group. Our results indicate that the QMOFs-PCMA combined with photothermal therapy may provide a promising treatment for biofilm-infected skin wounds.

Efficient Mn(II) removal by biological granular activated carbon filtration

Sufficient and sustainable manganese(II) removal is a challenging task to prevent Mn-related drinking water discoloration problems. This study investigated Mn(II) removal by granular activated carbon (GAC) filtration under various conditions. The results showed that biological GAC filter columns could reduce Mn(II) from 400 μg/L to 10 μg/L after a short ripening period, while sand filter columns did not show evident Mn(II) removal function. Water quality changes, pretreatment with NaClO and chemogenic MnO_x coating on GAC media surface did not influence the Mn(II) removal capacity of GAC filter columns. 16S rRNA gene sequencing showed that the abundance of potential Mn(II)-oxidizing bacteria in the GAC media was similar to that in the sand media. However, qPCR results indicated that GAC media colonized dramatically more biomass than sand media, resulting in highly effective Mn(II) removal by GAC filter columns. Under chlorinated conditions, GAC filtration underperformed sand filtration in Mn(II) removal, although activated carbon has been reported to be capable of catalyzing Mn(II) oxidation by chlorine. Fast chlorine decay in GAC filter columns made it hard to sustain chemical Mn(II) oxidation and thus led to less Mn(II) removal. This study highlighted the advantage of biological GAC filtration over sand filtration in Mn(II) removal.

Introducing Semi-Interpenetrating Networks of Chitosan and Ammonium-Quaternary Polymers for the Effective Removal of Waterborne Pathogens from Wastewaters

The present work aims to study the influence of ammonium-quaternary monomers and chitosan, obtained from different sources, upon the effect of semi-interpenetrating polymer network (semi-IPN) hydrogels upon the removal of waterborne pathogens and bacteria from wastewater. To this end, the study was focused on using vinyl benzyl trimethylammonium chloride (VBTAC), a water-soluble monomer with known antibacterial properties, and mineral-enriched chitosan extracted from shrimp shells, to prepare the semi-IPNs. By using chitosan, which still contains the native minerals (mainly calcium carbonate), the study intends to justify that the stability and efficiency of the semi-IPN bactericidal devices can be modified and better improved. The new semi-IPNs were characterized for composition, thermal stability and morphology using well-known methods. Swelling degree (SD%) and the bactericidal effect assessed using molecular methods revealed that hydrogels made of chitosan derived from shrimp shell demonstrated the most competitive and promising potential for wastewater (WW) treatment.

Influence of Quaternary Ammonium Salt Functionalized Chitosan Additive as Sustainable Filler for High-Density Polyethylene Composites

In this study, an antimicrobial packaging material was successfully developed with blends of high-density polyethylene (HDPE) and chitosan (CS) made by melt processing. In the different HDPE/CS composites, the CS content effect (up to 40%), and the addition of quaternary ammonium salt functionalized chitosan (CS-CTAB) as an additive were evaluated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analyses (TG), tensile strength, scanning electron microscopy (SEM) and antimicrobial activity. When analyzing the effect of the additive in the different HDPE/CS composites, it was observed that the compositions with 10 and 20 %wt of chitosan showed better elongation values (~13% and 10%) as well as a higher decomposition temperature at 20% mass loss (T20) varying from (321-332 °C and 302-312 °C), respectively, in relation to the other compositions, regardless of the type of additive used, it acted as an antimicrobial agent, promoting inhibition of microbial growth against the strains gram-positive and gram-negative used in this work, making the different HDPE/CS composites suitable candidates for use in food packaging.

Liquefied Polysaccharides-Based Polymer with Tunable Condensed State Structure for Antimicrobial Shield by Multiple Processing Methods

The phase behavior of biomolecules containing persistent molecular entities is generally limited due to their characteristic size that exceeds the intermolecular force field. Consequently, favorable properties normally associated with the liquid phase of a substance, such as fluidity or processability, are not relevant for the processing of biomolecules, thus hindering the optimal processing of biomolecules. The implied problem that arises is how to convert folded biomolecules to display a richer phase behavior. To alleviate this dilemma, a generic approach to liquefied polysaccharides-based polymers is proposed, resulting in a polysaccharide fluid with a tunable condensed state structure (solid-gel-liquid). Polysaccharide biobased fluids materials transcend the limits of the physical state of the biobased material itself and can even create completely new properties (different processing methods as well as functions) in a variety of polymeric structures. Considering the solvent incompatible high and low-temperature applications, this method will have a great influence on the design of nanostructures of biomolecular derivatives and is expected to transform biomass materials such as polysaccharide biopolymers from traditional use to resource use, ultimately leading to the efficient use of biomass materials and their sustainability.

Synthesis of Biobased and Hybrid Polyurethane Xerogels from Bacterial Polyester for Potential Biomedical Applications

Organic-inorganic xerogel networks were synthesized from bacterial poly (3-hydroxybutyrate) (PHB) for potential biomedical applications. Since silane-based networks usually demonstrate increased biocompatibility and mechanical properties, siloxane groups have been added onto polyurethane (PU) architectures. In this work, a diol oligomer (oligoPHB-diol) was first prepared from bacterial poly(3-hydroxybutyrate) (PHB) with an environmentally friendly method. Then, hexamethylene diisocyanate or biobased dimeryl diisocyanate was used as diisocyanate to react with the short oligoPHB-diol for the synthesis of different NCO-terminated PU systems in a bulk process and without catalyst. Various PU systems containing increasing NCO/OH molar ratios were prepared. Siloxane precursors were then obtained after reaction of the NCO-terminated PUs with (3-aminopropyl)triethoxysilane, resulting in silane-terminated polymers. These structures were confirmed by different analytical techniques. Finally, four series of xerogels were prepared via a sol-gel process from the siloxane precursors, and their properties were evaluated depending on varying parameters such as the inorganic network crosslinking density. The final xerogels exhibited adequate properties in connection with biomedical applications such as a high in vitro degradation up to 15 wt% after 12 weeks.

Smart and Active Food Packaging: Insights in Novel Food Packaging

The demand for more healthy foods with longer shelf life has been growing. Food packaging as one of the main aspects of food industries plays a vital role in meeting this demand. Integration of nanotechnology with food packaging systems (FPSs) revealed promising promotion in foods’ shelf life by introducing novel FPSs. In this paper, common classification, functionalities, employed nanotechnologies, and the used biomaterials are discussed. According to our survey, FPSs are classified as active food packaging (AFP) and smart food packaging (SFP) systems. The functionality of both systems was manipulated by employing nanotechnologies, such as metal nanoparticles and nanoemulsions, and appropriate biomaterials like synthetic polymers and biomass-derived biomaterials. “Degradability and antibacterial” and “Indicating and scavenging” are the well-known functions for AFP and SFP, respectively. The main purpose is to make a multifunctional FPS to increase foods’ shelf life and produce environmentally friendly and smart packaging without any hazard to human life.

Imminent antimicrobial bioink deploying cellulose, alginate, EPS and synthetic polymers for 3D bioprinting of tissue constructs

3D printing, one of its kinds has been a recent technological trend to fabricate complex and patterned biomaterial with controlled precision. With the conventional kick-start of printing metals and plastics, advancements in printing viable cells, polysaccharides or microbes themselves have been achieved. The additive antimicrobial properties in bioinks sourced from organic and inorganic materials have profound implications in tissue engineering. Cellulose, alginate, exopolysaccharides, ceramics and synthetic polymers are integrated as a viable component in inks and used for bio-printing. To date, bacterial infection and immunogenicity pose a potential health risk during a tissue implant or bone substitution. In order to mitigate microbial infection, antimicrobial bioinks with significant antimicrobial potential have been the much sought after strategies. This approach could be an effective frontline defense against microbial interference in tissue engineering and biomedical applications. An overview on the antimicrobial potential of polysaccharides as bioinks for 3D bioprinting has been critically reviewed.

Chitosan oligosaccharide-g-linalool polymer as inhibitor of hyaluronidase and collagenase activity

In this study, chitosan oligosaccharide (COS) was modified by grafting Linalool (Lin) on its backbone to improve its anti-inflammatory activity. By changing the molar ratios of COS to Lin, three different degrees of substitution COS-g-Lin1-3 were prepared. The degrees of substitution of derivatives were 0.65, 0.80 and 1.14 respectively. The structure of COS-g-Lin1-3 were characterized by UV-vis, FT-IR, ¹H NMR and elemental analysis in order to show the COS-g-Lin1-3 successfully synthesized. Besides, the thermal stability, solubility, pH stability as well as crystallinity were also investigated. The results revealed that the derivatives exhibited higher thermal stability and more remarkable anti-inflammatory property against hyaluronidase and collagenase than that of COS. The good biocompatibility made this novel material a promising and effective compound for anti-inflammatory applications.

Quaternary Ammonium Chitosans: The Importance of the Positive Fixed Charge of the Drug Delivery Systems

As a natural polysaccharide, chitosan has good biocompatibility, biodegradability and biosecurity. The hydroxyl and amino groups present in its structure make it an extremely versatile and chemically modifiable material. In recent years, various synthetic strategies have been used to modify chitosan, mainly to solve the problem of its insolubility in neutral physiological fluids. Thus, derivatives with negative or positive fixed charge were synthesized and used to prepare innovative drug delivery systems. Positively charged conjugates showed improved properties compared to unmodified chitosan. In this review the main quaternary ammonium derivatives of chitosan will be considered, their preparation and their applications will be described to evaluate the impact of the positive fixed charge on the improvement of the properties of the drug delivery systems based on these polymers. Furthermore, the performances of the proposed systems resulting from in vitro and ex vivo experiments will be taken into consideration, with particular attention to cytotoxicity of systems, and their ability to promote drug absorption.

N-Halamine Hydantoin-Containing Chitosan: Synthesis, Characterization, Thermal and Photolytic Stability Studies

Current demand for new protective materials ensuring sterility is systematically growing. The purpose of this work was the synthesis of the biocidal N-halamine hydantoin-containing chitosan (CS-CMH-Cl) and characterization of its properties. The functionalization of the chitosan by 5-hydantoinacetic acid substitution leads to obtaining the CS-CMH polymer, which was chlorinated in next step to transform N-H into N-Cl bonds. In this study, the possibility of forming two biocidal N-Cl bonds in hydantoin ring, grafted onto chitosan chains, was proved. The structure and stability of the prepared material was confirmed by spectroscopic (FTIR, NMR, colorimetric test) and microscopic analyses (SEM, AFM). Surface properties were investigated based on contact-angle measurements. In addition, the thermal and photochemical stability of the obtained samples were determined as functional features, determining the range of potential use. It was found that both modified chitosan polymers (CS-CMH and CS-CMH-Cl) were characterized by the smaller thermal stability and more hydrophilic and rougher surface than unmodified CS. Photooxidative degradation of the obtained materials was observed mainly on the sample surface. After irradiation, the surfaces became more hydrophilic-especially in the case of the CS-CMH-Cl-which is advantageous from the point of view of the antibacterial properties. Antibacterial tests against S. aureus and E. coli confirmed the antibacterial activities of received CS-CMH-Cl material.

Preparation, characterization and antibacterial properties of 6-deoxy-6-arginine modified chitosan

In this study, 6-deoxy-6-arginine modified chitosan (DAC), was synthesized and characterized by Fourier Transform Infrared Spectroscopy (FTIR), ¹H and ¹³C nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and elemental analysis. The arginine was grafted onto C6 groups of chitosan. Antibacterial activity of DAC against gram-negative bacteria Escherichia coli (E. coli) and gram-positive bacteria Staphylococcus aureus (S. aureus) were investigated at concentration between 0.02 mg/mL and 10 mg/mL. Cell viability assessment was estimated in vitro with Caco-2 and L929 cells. Water solubility of DAC at different pH was also evaluated. The results showed that the minimum inhibitory concentration (MICs) of DAC against S. aureus and E. coli were 0.078 mg/mL and 0.312 mg/mL, respectively. The minimum bactericidal concentration (MBC) against S. aureus and E. coli was 0.625 mg/mL. The cytotoxicity of chitosan and DAC was not significantly different. It demonstrated that DAC might be a potential safe antibacterial agent.

Bio-Based Polymers with Antimicrobial Properties towards Sustainable Development

This article concisely reviews the most recent contributions to the development of sustainable bio-based polymers with antimicrobial properties. This is because some of the main problems that humanity faces, nowadays and in the future, are climate change and bacterial multi-resistance. Therefore, scientists are trying to provide solutions to these problems. In an attempt to organize these antimicrobial sustainable materials, we have classified them into the main families; i.e., polysaccharides, proteins/polypeptides, polyesters, and polyurethanes. The review then summarizes the most recent antimicrobial aspects of these sustainable materials with antimicrobial performance considering their main potential applications in the biomedical field and in the food industry. Furthermore, their use in other fields, such as water purification and coating technology, is also described. Finally, some concluding remarks will point out the promise of this theme.

Applications of cellulose and chitin/chitosan derivatives and composites as antibacterial materials: current state and perspectives

The bacterial infections have always a serious problem to public health. Scientists are developing new antibacterial materials to overcome this problem. Polysaccharides are promising biopolymers due to their diverse biological functions, low toxicity, and high biodegradability. Chitin and chitosan have antibacterial properties due to their cationic nature, while cellulose/bacterial cellulose does not possess any antibacterial activity. Moreover, the insolubility of chitin in common solvents, the poor solubility of chitosan in water, and the low mechanical properties of chitosan have restricted their biomedical applications. In order to solve these problems, chemical modifications such as quaternization, carboxymethylation, cationization, or surface modification of these polymers with different antimicrobial agents, including metal and metal oxide nanoparticles, are carried out to obtain new materials with improved physiochemical and biological properties. This mini review describes the recent progress in such derivatives and composites with potential antibacterial applications.

Effect of the linear aliphatic amine functionalization on in vitro transfection efficiency of chitosan nanoparticles

The aim of this study is to prepare the long linear aliphatic amine pendant group-functionalized chitosan based nanoparticulate gene carrier system with improved properties for the efficient transfection. The amine functionalized chitosan (MChi) was synthesized by using N-(2-hydroxyethyl)ethylenediamine (HE-EDA) and characterized for the first time. The nanoparticles of MChi (nMChi) were prepared by ionic gelation method, and their particle size, polydispersity (PDI), zeta potential (mV), gene binding capacity and cytotoxicity were determined. Green Fluorescent Protein circular plasmid DNA (pEGFN1) loaded nanoparticles (gnMChi) were used in the transfection studies. The results showed that nMChi with a particle size of 102.9 nm and zeta potential of 41.9 ± 5.63 mV was non-toxic, had high transfection efficiency in Human Embryonic Kidney 293 and Primary Ovine Fibroblast cell lines and would be used as an efficient gene carrier system.

Original Macromolecular Architectures Based on poly(ε-caprolactone) and poly(ε-thiocaprolactone) Grafted onto Chitosan Backbone

Polyester and/or polythioester grafted chitosan copolymers were synthesized. For that, poly(ε-caprolactone) (PCL), poly(ε-thiocaprolactone) (PTCL), and their copolymers were first synthesized by ring opening polymerization. Copolymers with caprolactone:thiocaprolactone (CL:TCL) molar ratios of 2:1, 1:1, 1:2 were synthesized. All of the synthesized macromolecular architectures were characterized using different spectral (Fourier transform infrared (FTIR), proton nuclear magnetic resonance (¹H-NMR), X-Ray diffraction (XRD)) and thermal (Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA)) methods. Grafting was then performed according two distinct routes: (i) using a blend of both homopolymers (PCL and PTCL) or (ii) using pre-synthesized copolymers with controlled CL:TCL ratios. Hexamethylene diisocyanate was used as a grafting/coupling agent through urethane bonds with high yield. Grafting preferentially occurred at sulfur sites. The results indicated that PTCL is more reactive and favorable than PCL for grafting onto chitosan. With the homopolymers blend grafting route, the corresponding materials mostly had a higher PTCL portion than expected. To obtain polyester grafted chitosan with a determined CL:TCL ratio, the copolymer grafting route would yield better results.

Fabrication of Bifunctional Chitosan-Based Flocculants: Characterization, Assessment of Flocculation, and Sterilization Performance

In this study, a series of chitosan-based quaternary ammonium graft flocculants, namely chitosan-graft-poly(acrylamide and methacryloyl ethyl trimethyl ammonium chloride) [CTS-g-P(AM-DMC)], was successfully synthesized by plasma initiation, and the as-prepared [CTS-g-P(AM-DMC)] had both flocculation and sterilization functions. Various characterization techniques were used to study the structure and physicochemical properties of the chitosan-based flocculants. ¹H nuclear magnetic resonance spectroscopy (¹H NMR), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), and thermogravimetric analysis/differential scanning calorimetry (TG/DSC) confirmed the successful synthesis of CTS-g-P(AM-DMC). Scanning electron microscopy (SEM) analysis exhibited that CTS-g-P(AM-DMC) contained a smooth convex and porous structure with an enormous surface area. CTS-g-P(AM-DMC) was then used to flocculate the simulated wastewater of the kaolin suspension and the Salmonella suspension. Besides external factors, such as the dosage of flocculant and pH, the effect of the internal factor graft ratio was also evaluated. The experimental results showed that CTS-g-P(AM-DMC) also revealed a strong sterilization effect, aside from the excellent flocculation effect. Moreover, the sterilization mechanism was investigated through a series of conductivity measurements and the analysis of fluorescence-based cell live/dead tests. The results indicated that CTS-g-P(AM-DMC) destroyed the cell membrane of Salmonella through its grafted quaternary ammonium salt, thereby exhibiting sterilization property.

Synthesis, Characterization, and Antifungal Activity of Pyridine-Based Triple Quaternized Chitosan Derivatives

In this study, a series of triple quaternized chitosan derivatives, including 6-O-[(2-hydroxy-3-trimethylammonium)propyl]-2-N-(1-pyridylmethyl-2-ylmethyl)-N,N-dimethyl chitosan chloride (7), 6-O-[(2-hydroxy-3-trimethylammonium)propyl]-2-N-(1-pyridylmethyl-3-yl- methyl)-N,N-dimethyl chitosan chloride (8), and 6-O-[(2-hydroxy-3-trimethylammonium)propyl]- 2-N-(1-pyridylmethyl-4-ylmethyl)-N,N-dimethyl chitosan chloride (9) were successfully designed and synthesized via reacting epoxypropyl trimethylammonium chloride with the N-pyridinium double quaternized chitosan derivatives. Detailed structural characterization was carried out using FT-IR and ¹H-NMR spectroscopy, and elemental analysis. Besides, the activity of the triple quaternized chitosan derivatives against three common plant pathogenic fungi, Watermelon fusarium, Fusarium oxysporum, and Phomopsis asparagi, was investigated in vitro. The results indicated that the triple quaternized chitosan derivatives had enhanced antifungal activity when compared to double quaternized chitosan derivatives and chitosan, especially at 1.0 mg/mL, which confirmed the theory that the higher density of positive charge contributed to the antifungal activity. Moreover, 8 with an almost 99% inhibitory index showed the better antifungal activity against Watermelon fusarium. Moreover, the cytotoxicity of the products was also evaluated in vitro on 3T3-L1 cells and all the triple quaternized chitosan derivatives exhibited low cytotoxicity. These results suggested that triple quaternized chitosan derivatives may be used as good antifungal biomaterials.

HDPE/Chitosan Blends Modified with Organobentonite Synthesized with Quaternary Ammonium Salt Impregnated Chitosan

In this study, blends based on a high density polyethylene (HDPE) and chitosan (CS) were successfully prepared by melt processing, in a laboratory internal mixer. The CS biopolymer content effect (up to maximum of 40%), and, the addition of bentonite clay modified with quaternary ammonium salt (CTAB) impregnated chitosan as a compatibilizing agent, on the properties of the blends was analyzed by Fourier transform-infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analyses (TG), tensile strength, and scanning electron microscopy (SEM). The use of clay modified with CTAB impregnated chitosan, employing a method developed here, improved the compatibility of HDPE with chitosan, and therefore the thermal and some of the mechanical properties were enhanced, making HDPE/chitosan blends suitable candidates for food packaging. It was possible to obtain products of synthetic polymer, HDPE, with natural polymer, chitosan, using a method very used industrially, with acceptable and more friendly properties to the environment, when compared to conventional synthetic polymers. In addition, due to the possibility of impregnated chitosan with quaternary ammonium salt exhibit higher antibacterial activity than neat chitosan, the HDPE/chitosan/organobentonite blends may be potentially applied in food containers to favor the preservation of food for a longer time in comparison to conventional materials.

Valorisation of chitinous biomass for antimicrobial applications

The chitin and chitosan market worldwide has shown tremendous growth, propelled by the expansion in the application domain. The market volume is projected to be more than 155 thousand metric tons by the year 2022. The global market for chitin and chitosan derivatives is expected to reach $4.2 billion by 2021 up from $2.0 billion in 2016 at a compound annual growth rate (CAGR) of 15.4%, from 2016 to 2021. Among chitin derivatives, chitosan is projected to offer the highest growth potential. The demand for a reliable source of high quality chitosan is rapidly increasing as new value added products enter the market. At the same time the growth of value added chitosan based products are limited by the availability of a sustainable supply chain. Antimicrobial properties are of special interest in the packaging, cosmetic, food and biomedical sector. Most of the latter applications warrants high-volume and low cost materials. However, the process chemistry for bulk chitosan manufacturing is currently not very environmentally friendly. Green technologies for chitosan modification have increased in recent years and now face the challenge of economic viability. In this review the status of antimicrobial chitosan derivatives will be reported with a critical review of the chemical technologies that would mitigate the commercialisation of these biopolymers in the antimicrobial biopolymer market sector. The amount of publications per annum has increased exponentially and the lack of global standardised antimicrobial test protocols make it rather challenging to properly evaluate the relative efficacy of these polymers.