Chitosan derivatives obtained by chemical modifications for biomedical and environmental applications

One-pot Formulation of Cationic Oligochitosan Coated Nanoparticles via Photo- Polymerization Induced Self-Assembly

During last few decades, oligochitosan (OCS)-coated nanoparticles have received great interest for nanomedicine, food and environment applications. However, their current formulation techniques are time-consuming with multi-synthesis/purification steps and sometimes require the use of organic solvents, crosslinkers and surfactants. Herein, we report a facile and rapid one-pot synthesis of OCS-based nanoparticles using photo-initiated reversible addition fragmentation chain transfer polymerization-induced self-assembly (Photo-RAFT PISA) under UV-irradiation at room temperature. To achieve this, OCS was first functionalized by a chain transfer agent (CTA) resulting in a macromolecular chain transfer agent (OCS-CTA), which will act as a reactive electrostatic/steric stabilizer. Owing to its UV-sensitivity, OCS-CTA was then used as photo-iniferter to initiate the polymerization of 2-hydroxypropyl methacrylate (HPMA) in aqueous acidic buffer, resulting in OCS-g-PHPMA amphiphilic grafted copolymers which self-assemble into nano-objects. Transmission electron microscopy and light scattering analysis reveal formation of spherical nanostructures.

Chitosan alchemy: transforming tissue engineering and wound healing

Chitosan, a biopolymer acquired from chitin, has emerged as a versatile and favorable material in the domain of tissue engineering and wound healing. Its biocompatibility, biodegradability, and antimicrobial characteristics make it a suitable candidate for these applications. In tissue engineering, chitosan-based formulations have garnered substantial attention as they have the ability to mimic the extracellular matrix, furnishing an optimal microenvironment for cell adhesion, proliferation, and differentiation. In the realm of wound healing, chitosan-based dressings have revealed exceptional characteristics. They maintain a moist wound environment, expedite wound closure, and prevent infections. These formulations provide controlled release mechanisms, assuring sustained delivery of bioactive molecules to the wound area. Chitosan's immunomodulatory properties have also been investigated to govern the inflammatory reaction during wound healing, fostering a balanced healing procedure. In summary, recent progress in chitosan-based formulations portrays a substantial stride in tissue engineering and wound healing. These innovative approaches hold great promise for enhancing patient outcomes, diminishing healing times, and minimizing complications in clinical settings. Continued research and development in this field are anticipated to lead to even more sophisticated chitosan-based formulations for tissue repair and wound management. The integration of chitosan with emergent technologies emphasizes its potential as a cornerstone in the future of regenerative medicine and wound care. Initially, this review provides an outline of sources and unique properties of chitosan, followed by recent signs of progress in chitosan-based formulations for tissue engineering and wound healing, underscoring their potential and innovative strategies.

Injectable Double Crosslinked Hydrogel-Polypropylene Composite Mesh for Repairing Full-Thickness Abdominal Wall Defects

Abdominal wall defects are common clinical diseases, and mesh repair is the standard treatment method. The most commonly used polypropylene (PP) mesh in clinical practice has the advantages of good mechanical properties, stable performance, and effective tissue integration effect. However, direct contact between abdominal viscera and PP mesh can lead to severe abdominal adhesions. To prevent this, the development of a hydrogel-PP composite mesh with anti-adhesive properties may be an effective measure. Herein, biofunctional hydrogel loaded with rosmarinic acid is developed by modifying chitosan and Pluronic F127, which possesses suitable physical and chemical properties and commendable in vitro biocompatibility. In the repair of full-thickness abdominal wall defects in rats, hydrogels are injected onto the surface of PP mesh and applied to intraperitoneal repair. The results indicate that the use of hydrogel-PP composite mesh can alleviate abdominal adhesions resulting from traditional PP mesh implantation by decreasing local inflammatory response, reducing oxidative stress, and regulating the fibrinolytic system. Combined with the tissue integration ability of PP mesh, hydrogel-PP composite mesh has great potential for repairing full-thickness abdominal wall defects.

Synthesis of Thermoresponsive Chitosan-graft-Poly(N-isopropylacrylamide) Hybrid Copolymer and Its Complexation with DNA

A hybrid synthetic-natural, thermoresponsive graft copolymer composed of poly(N-isopropyl acrylamide) (PNIPAM) side chains, prepared via RAFT polymerization, and a chitosan (Chit) polysaccharide backbone, was synthesized via radical addition-fragmentation reactions using the "grafting to" technique, in aqueous solution. ATR-FTIR, TGA, polyelectrolyte titrations and 1H NMR spectroscopy were employed in order to validate the Chit-g-PNIPAM copolymer chemical structure. Additionally, 1H NMR spectra and back conductometric titration were utilized to quantify the content of grafted PNIPAM side chains. The resulting graft copolymer contains dual functionality, namely both pH responsive free amino groups, with electrostatic complexation/coordination properties, and thermoresponsive PNIPAM side chains. Particle size measurements via dynamic light scattering (DLS) were used to study the thermoresponsive behavior of the Chit-g-PNIPAM copolymer. Thermal properties examined by TGA showed that, by the grafting modification with PNIPAM, the Chit structure became more thermally stable. The lower critical solution temperature (LCST) of the copolymer solution was determined by DLS measurements at 25-45 °C. Furthermore, dynamic and electrophoretic light scattering measurements demonstrated that the Chit-g-PNIPAM thermoresponsive copolymer is suitable of binding DNA molecules and forms nanosized polyplexes at different amino to phosphate groups ratios, with potential application as gene delivery systems.

A novel N-acetylglucosamine-6-phosphate deacetylase that is essential for chitin utilization in the chitinolytic bacterium, Chitiniphilus shinanonensis

AIMS

We aimed to investigate the function of an unidentified gene annotated as a PIG-L domain deacetylase (cspld) in Chitiniphilus shinanonensis SAY3. cspld was identified using transposon mutagenesis, followed by negatively selecting a mutant incapable of growing on chitin, a polysaccharide consisting of N-acetyl-d-glucosamine (GlcNAc). We focused on the physiological role of CsPLD protein in chitin utilization.

METHODS AND RESULTS

Recombinant CsPLD expressed in Escherichia coli exhibited GlcNAc-6-phosphate deacetylase (GPD) activity, which is involved in the metabolism of amino sugars. However, SAY3 possesses two genes (csnagA1 and csnagA2) in its genome that code for proteins whose primary sequences are homologous to those of typical GPDs. Recombinant CsNagA1 and CsNagA2 also exhibited GPD activity with 23 and 1.6% of catalytic efficiency (kcat/Km), respectively, compared to CsPLD. The gene-disrupted mutant, Δcspld was unable to grow on chitin or GlcNAc, whereas the three mutants, ΔcsnagA1, ΔcsnagA2, and ΔcsnagA1ΔcsnagA2 grew similarly to SAY3. The determination of GPD activity in the crude extracts of each mutant revealed that CsPLD is a major enzyme that accounts for almost all cellular activities.

CONCLUSIONS

Deacetylation of GlcNAc-6P catalyzed by CsPLD (but not by typical GPDs) is essential for the assimilation of chitin and its constituent monosaccharide, GlcNAc, as a carbon and energy source in C. shinanonensis.

Advances in guided bone regeneration membranes: a comprehensive review of materials and techniques

Guided tissue/bone regeneration (GTR/GBR) is a widely used technique in dentistry to facilitate the regeneration of damaged bone and tissue, which involves guiding materials that eventually degrade, allowing newly created tissue to take its place. This comprehensive review the evolution of biomaterials for guided bone regeneration that showcases a progressive shift from non-resorbable to highly biocompatible and bioactive materials, allowing for more effective and predictable bone regeneration. The evolution of biomaterials for guided bone regeneration GTR/GBR has marked a significant progression in regenerative dentistry and maxillofacial surgery. Biomaterials used in GBR have evolved over time to enhance biocompatibility, bioactivity, and efficacy in promoting bone growth and integration. This review also probes into several promising fabrication techniques like electrospinning and latest 3D printing fabrication techniques, which have shown potential in enhancing tissue and bone regeneration processes. Further, the challenges and future direction of GTR/GBR are explored and discussed.

Chitosan-based Schiff bases: Promising materials for biomedical and industrial applications

There is plenty of scope for modifying chitosan, an only polycationic natural polysaccharide, owing to its reactive functional groups, namely hydroxyl and amino groups. Although innumerable numbers of chitosan derivatives have been synthesized by modifying these groups and reported elsewhere, in this review article, an attempt has been exclusively made to demonstrate the syntheses of various chitosan-based Schiff bases (CSBs) simply by allowing the reactions of reactive amino groups of chitosan with different aldehydes/ketones of interest. Due to their very peculiar and unique characteristics, such as biodegradability, biocompatibility, metal-binding capability, etc., they are found to be very useful for diversified applications. Thus, we have also attempted to showcase their very specific biomedical fields, including tissue engineering, drug delivery, and wound healing, to name a few. In addition, we have also discussed the utilization of CSBs for industrial applications such as wastewater treatment, catalysis, corrosion inhibition, sensors, etc.

Recent advances in chitosan-based materials; The synthesis, modifications and biomedical applications

The attention to polymer-based biomaterials, for instance, chitosan and its derivatives, as well as the techniques for using them in numerous scientific domains, is continuously rising. Chitosan is a decomposable naturally occurring polymeric material that is mostly obtained from seafood waste. Because of its special ecofriendly, biocompatible, non- toxic nature as well as antimicrobial properties, chitosan-based materials have received a lot of interest in the field of biomedical applications. The reactivity of chitosan is mainly because of the amino and hydroxyl groups in its composition, which makes it further fascinating for various uses, including biosensing, textile finishing, antimicrobial wound dressing, tissue engineering, bioimaging, gene, DNA and drug delivery and as a coating material for medical implants. This study is an overview of the different types of chitosan-based materials which now a days have been fabricated by applying different techniques and modifications that include etherification, esterification, crosslinking, graft copolymerization and o-acetylation etc. for hydroxyl groups' processes and acetylation, quaternization, Schiff's base reaction, and grafting for amino groups' reactions. Furthermore, this overview summarizes the literature from recent years related to the important applications of chitosan-based materials (i.e., thin films, nanocomposites or nanoparticles, sponges and hydrogels) in different biomedical applications.

A novel endo-type chitinase possessing chitobiase activity derived from the chitinolytic bacterium, Chitiniphilus shinanonensis SAY3T

One of the chitinases (ChiG) derived from the chitinolytic bacterium Chitiniphilus shinanonensis SAY3T exhibited chitobiase activity cleaving dimers of N-acetyl-D-glucosamine (GlcNAc) into monomers, which is not detected in typical endo-type chitinases. Analysis of the reaction products for GlcNAc hexamers revealed that all the five internal glycosidic bonds were cleaved at the initial stage. The overall reaction catalyzed by chitobiases toward GlcNAc dimers was similar to that catalyzed by N-acetyl-D-glucosaminidases (NAGs). SAY3 possesses two NAGs (ChiI and ChiT) that are thought to be important in chitin catabolism. Unexpectedly, a triple gene-disrupted mutant (ΔchiIΔchiTΔchiG) was still able to grow on synthetic medium containing GlcNAc dimers or powdered chitin, similar to the wild-type SAY3, although it exhibited only 3% of total cellular NAG activity compared to the wild-type. This indicates the presence of unidentified enzyme(s) capable of supporting normal bacterial growth on the chitin medium by NAG activity compensation.

Sustainable functionalized chitosan based nano-composites for wound dressings applications: A review

Functionalized chitosan nanocomposites have been studied for wound dressing applications due to their excellent antibacterial and anti-fungal properties. Polysaccharides show excellent antibacterial and drug-release properties and can be utilized for wound healing. In this article, we comprise distinct approaches for chitosan functionalization, such as photosensitizers, dendrimers, graft copolymerization, quaternization, acylation, carboxyalkylation, phosphorylation, sulfation, and thiolation. The current review article has also discussed brief insights on chitosan nanoparticle processing for biomedical applications, including wound dressings. The chitosan nanoparticle preparation technologies have been discussed, focusing on wound dressings owing to their targeted and controlled drug release behavior. The future directions of chitosan research include; a) finding an effective solution for chronic wounds, which are unable to heal completely; b) providing effective wound healing solutions for diabetic wounds and venous leg ulcers; c) to better understanding the wound healing mechanism with such materials which can help provide the optimum solution for wound dressing; d) to provide an improved treatment option for wound healing.

Multi-enzyme Machinery for Chitin Degradation in the Chitinolytic Bacterium Chitiniphilus shinanonensis SAY3T

The chitinolytic bacterium, Chitiniphilus shinanonensis SAY3T was examined to characterize its chitin-degrading enzymes in view of its potential to convert biomass chitin into useful saccharides. A survey of the whole-genome sequence revealed 49 putative genes encoding polypeptides that are thought to be related to chitin degradation. Based on an analysis of the relative quantity of each transcript and an assay for chitin-degrading activity of recombinant proteins, a chitin degradation system driven by 19 chitinolytic enzymes was proposed. These include sixteen endo-type chitinases, two N-acetylglucosaminidases, and one lipopolysaccharide monooxygenase that catalyzes the oxidative cleavage of glycosidic bonds. Among the 16 chitinases, ChiL was characterized by its remarkable transglycosylation activity. Of the two N-acetylglucosaminidases (ChiI and ChiT), ChiI was the major enzyme, corresponding to > 98% of the total cellular activity. Surprisingly, a chiI-disrupted mutant was still able to grow on medium with powdered chitin or GlcNAc dimer. However, its growth rate was slightly lower compared to that of the wild-type SAY3. This multi-enzyme machinery composed of various types of chitinolytic enzymes may support SAY3 to efficiently utilize native chitin as a carbon and energy source and may play a role in developing an enzymatic process to decompose and utilize abundant chitin at the industrial scale.

Seed Priming Modulates Physiological and Agronomic Attributes of Maize (Zea mays L.) under Induced Polyethylene Glycol Osmotic Stress

Drought and osmotic stresses are major threats to agricultural crops as they affect plants during their life cycle. The seeds are more susceptible to these stresses during germination and establishment of seedlings. To cope with these abiotic stresses, various seed priming techniques have broadly been used. The present study aimed to assess seed priming techniques under osmotic stress. Osmo-priming with chitosan (1 and 2%), hydro-priming with distilled water, and thermo-priming at 4 °C were used on the physiology and agronomy of Zea mays L. under polyethylene glycol (PEG-4000)-induced osmotic stress (-0.2 and -0.4 MPa). The vegetative response, osmolyte content, and antioxidant enzymes of two varieties (Pearl and Sargodha 2002 White) were studied under induced osmotic stress. The results showed that seed germination and seedling growth were inhibited under osmotic stress and germination percentage, and the seed vigor index was enhanced in both varieties of Z. mays L. with chitosan osmo-priming. Osmo-priming with chitosan and hydro-priming with distilled water modulated the level of photosynthetic pigments and proline, which were reduced under induced osmotic stress; moreover, the activities of antioxidant enzymes were improved significantly. In conclusion, osmotic stress adversely affects the growth and physiological attributes; on the contrary, seed priming ameliorated the stress tolerance resistance of Z. mays L. cultivars to PEG-induced osmotic stress by activating the natural antioxidation enzymatic system and accumulating osmolytes.

Advanced phosphocreatine-grafted chitosan hydrogel promote wound healing by macrophage modulation

Background: The repair of wounds usually caused by trauma or other chronic diseases remained challenging in clinics due to the potential risk of inflammation and inadequate tissue regenerative properties. Among them, the behaviour of immune cells, such as macrophages, is critical in tissue repair. Materials and methods: In this study, a water-soluble phosphocreatine-grafted methacryloyl chitosan (CSMP) was synthesized with a one-step lyophilization method, followed by the fabrication of CSMP hydrogel with a photocrosslinked method. The microstructure, water absorption and mechanical properties for the hydrogels were investigated. Then, the macrophages were co-cultured with hydrogels and the pro-inflammatory factors and polarization markers for these macrophages were detected through real-time quantitative polymerase chain reaction (RT-qPCR), Western blot (WB), and flow cytometry methods. Finally, the CSMP hydrogel was implanted in a wound defect area in mice to test its ability to promote wound healing. Results: The lyophilized CSMP hydrogel had a porous structure with pores ranging in size from 200 to 400 μm, which was larger than the CSM hydrogel's. The lyophilized CSMP hydrogel possessed a higher water absorption rate compared with the CSM hydrogel. The compressive stress and modulus of these hydrogels were increased in the initial 7 days immersion and then gradually decreased during the in vitro immersion in PBS solution up to 21 days; the CSMP hydrogel showed a higher value in these parameters versus the CSM hydrogel. The CSMP hydrogel inhibited the expression of inflammatory factors such as interleukin-1β (IL-1β), IL-6, IL-12, and tumor necrosis factor-α (TNF-α) in an in vitro study cocultured with pro-inflammatory factors in pre-treated bone marrow-derived macrophages (BMM). The mRNA sequencing results showed that the CSMP hydrogel might inhibit the macrophages' M1 type polarization through the NF-κB signaling pathway. Furthermore, when compared to the control group, the CSMP hydrogel promoted more skin area repair in the mouse wound defect area, and inflammatory factors such as IL-1β, IL-6, and TNF-α were lower in the repaired tissue for the CSMP group. Conclusion: This phosphate-grafted chitosan hydrogel showed great promise for wound healing through regulating the macrophage's phenotype via the NF-κB signaling pathway.

Chitosan Hydrogel as Tissue Engineering Scaffolds for Vascular Regeneration Applications

Chitosan hydrogels have a wide range of applications in tissue engineering scaffolds, mainly due to the advantages of their chemical and physical properties. This review focuses on the application of chitosan hydrogels in tissue engineering scaffolds for vascular regeneration. We have mainly introduced these following aspects: advantages and progress of chitosan hydrogels in vascular regeneration hydrogels and the modification of chitosan hydrogels to improve the application in vascular regeneration. Finally, this paper discusses the prospects of chitosan hydrogels for vascular regeneration.

Double-Network Chitosan-Based Hydrogels with Improved Mechanical, Conductive, Antimicrobial, and Antibiofouling Properties

In recent years, the antimicrobial activity of chitosan-based hydrogels has been at the forefront of research in wound healing and the prevention of medical device contamination. Anti-infective therapy is a serious challenge given the increasing prevalence of bacterial resistance to antibiotics as well as their ability to form biofilms. Unfortunately, hydrogel resistance and biocompatibility do not always meet the demands of biomedical applications. As a result, the development of double-network hydrogels could be a solution to these issues. This review discusses the most recent techniques for creating double-network chitosan-based hydrogels with improved structural and functional properties. The applications of these hydrogels are also discussed in terms of tissue recovery after injuries, wound infection prevention, and biofouling of medical devices and surfaces for pharmaceutical and medical applications.

Physicochemical and Structural Characterization of Alkali-Treated Biopolymer Sphingan WL Gum from Marine Sphingomonas sp. WG

Sphingan WL gum (WL), a kind of exopolysaccharide, is produced by Sphingomonas sp. WG, which was screened from sea mud samples of Jiaozhou Bay by our group. The solubility of WL was investigated in this work. First, 1 mg/mL of WL solution was stirred at room temperature for at least 2 h to obtain a uniform opaque liquid, and further the solution became clear with the increased NaOH and stirring time. Subsequently, the structural features, solubility, and rheological properties of WL before and after alkali treatment were compared systematically. FTIR, NMR, and zeta potential results indicate that the alkali causes acetyl group hydrolysis and carboxyl group deprotonation. XRD, DLS, GPC, and AFM results suggest that the alkali destroys the ordered arrangement and inter- and intrachain entanglement of polysaccharide chains. In the same case, 0.9 M NaOH-treated WL presents better solubility (stirring for 15 min to obtain a clarified solution) but, unsurprisingly, worsens rheological properties. All results demonstrated that the good solubility and transparency of alkali-treated WL will help promote its postmodification and application.

MOFs-Modified Electrochemical Sensors and the Application in the Detection of Opioids

Opioids are widely used in clinical practice, but drug overdoses can lead to many adverse reactions, and even endanger life. Therefore, it is essential to implement real-time measurement of drug concentrations to adjust the dosage given during treatment, keeping drug levels within therapeutic levels. Metal-Organic frameworks (MOFs) and their composite materials modified bare electrode electrochemical sensors have the advantages of fast production, low cost, high sensitivity, and low detection limit in the detection of opioids. In this review, MOFs and MOFs composites, electrochemical sensors modified with MOFs for the detection of opioids, as well as the application of microfluidic chips in combination with electrochemical methods are all reviewed, and the potential for the development of microfluidic chips electrochemical methods with MOFs surface modifications for the detection of opioids is also prospected. We hope that this review will provide contributions to the study of electrochemical sensors modified with MOFs for the detection of opioids.

Recent Developments in Biopolymer-Based Hydrogels for Tissue Engineering Applications

Hydrogels are being investigated for their application in inducing the regeneration of various tissues, and suitable conditions for each tissue are becoming more apparent. Conditions such as the mechanical properties, degradation period, degradation mechanism, and cell affinity can be tailored by changing the molecular structure, especially in the case of polymers. Furthermore, many high-functional hydrogels with drug delivery systems (DDSs), in which drugs or bioactive substances are contained in controlled hydrogels, have been reported. This review focuses on the molecular design and function of biopolymer-based hydrogels and introduces recent developments in functional hydrogels for clinical applications.

Is nanoparaquat safer than bulk paraquat? An in vitro and in vivo evaluation

Paraquat (PQ) is an herbicide which has brought some health problems through the production of reactive oxygen species. The increasing interest in the novel formulation of agrochemicals has been aiming to provide safety for non-target organisms. Chitosan is a well-known non-toxic polymer, commonly used in preparing particles via ionotropic gelation. In this study, we prepared PQ nanoparticles (PQNPs) and evaluated their toxicity in vivo and in vitro. PQNPs were prepared and characterized in two forms, with and without the utilization of chitosan. Relative cell survival of PQNPs were studied against bulk PQ in HEK-293. Also, the acute lung injury of PQNP was assessed against treatment with acetylcysteine. Total antioxidant capacity (TAC), lipid peroxidation (LPO), total thiol groups (TTG), and hydroxyproline, along with histological changes were assessed in the lungs. The size, zeta potential, and polydispersity index of the optimum particles were about 157.7 ± 7.03, 22.25 ± 4.52, and 0.701, respectively. The encapsulation efficiency was 65.11 ± 10.45, and the loading percent of PQ was 58.57 ± 2.37. PQNPs showed an initial burst of PQ release followed by a zero-degree pattern. PQNPs displayed lower cell cytotoxicity compared to bulk PQ. LPO, TAC, TTG, and hydroxyproline levels in lungs generally showed more satisfying status in PQNPQs as well. The levels of oxidative status markers indicate lower oxidative damage in lungs and a more desirable response to acetylcysteine treatment, in line with histological changes. PQ loaded in chitosan-alginate particles offers safer characteristics compared with bulk PQ.

Polymer Grafting and its chemical reactions

Polymer grafting is a technique to improve the morphology, chemical, and physical properties of the polymer. This technique has the potential to improve the existing conduction and properties of polymers other than charge transport; as a result, it enhances the solubility, nano-dimensional morphology, biocompatibility, bio-communication, and other property of parent polymer. A polymer's physicochemical properties can be modified even further by creating a copolymer with another polymer or by grafting. Here in the various chemical approaches for polymer grafting, like free radical, click reaction, amide formation, and alkylation have been discussed with their importance, moreover the process and its importance are covered comprehensively with their scientific explanation. The present review also covers the effectiveness of the graft-to approaches and its application in various fields, which will give reader a glimpse about polymer grafting and its uses.

Chitosan application towards the improvement of grapevine performance and wine quality

Intensification of agrochemicals application in vineyards has raised several concerns in Viticulture and Oenology value chain. Efforts have been developed to optimize grapevine health and productivity, assuring that viticulture is sustainable and competitive in today’s wine market. Viticulture practices have constantly been improved for a more sustainable and environment-friendly production, reducing the application of agrochemicals, replacing them by natural compounds that can have a double effect: protect grapevine against pathogens and improve compounds related to grape organoleptic quality. In this context, the development and optimization of alternative strategies to improve and enhance plant defences and grape/wine quality is becoming a necessity. Since the 1980s, chitosan has become a compound of special interest due to its double effect as elicitor and grapevine biostimulant, representing a complement to soil fertilisation, and reducing the negative effects nutrients leaching into the groundwater. The present review aims to present the wide possibilities of chitosan applications on grapevines to prevent and combat the main diseases and to improve wine quality. In this way, relevant studies about chitosan application will be presented as well as some concerns and limitations in order to cover the knowledge gaps inherent to its application in vineyard and wine as well.

A comparative study on Fe(III)-chitosan and Fe(III)-chitosan-CTAB composites for As(V) removal from water: preparation, characterization and reaction mechanism

Fe(III)-chitosan and Fe(III)-chitosan-CTAB composites were prepared using an ionotropic gelation method. Various techniques were used to analyze the morphology, structure, and property of the adsorbents, including SEM, EDS, FT-IR, XPS, and zeta potential. Compared with Fe(III)-chitosan, Fe(III)-chitosan-CTAB was more effective for As(V) adsorption at a wide range of pH (3.0-8.0). The adsorption of As(V) onto Fe(III)-chitosan and Fe(III)-chitosan-CTAB could reach equilibrium in 20 min, and their maximum adsorption capacities were 33.85 and 31.69 mg g^‒1, respectively. The adsorption kinetics was best described by the pseudo-second-order model (R² = 0.998 and 0.992), whereas the adsorption isotherm was fitted well by the Freundlich model (R² = 0.963 and 0.987). The presence of H₂PO₄^- significantly inhibited the adsorption of As(V) onto Fe(III)-chitosan and Fe(III)-chitosan-CTAB, and humic acid also led to a slight decrease in As(V) adsorption by Fe(III)-chitosan-CTAB. Over 94% of As(V) at the initial concentration of no more than 5 mg L^-1 was removed from real water by the two adsorbents. 1% (w/v) NaOH solution was determined to be the most suitable desorption agent. Fe(III)-chitosan and Fe(III)-chitosan-CTAB still maintained their initial adsorption capacities after five adsorption-desorption cycles. Based on different characterization results, both electrostatic attraction and surface complexation mechanisms played important roles in As(V) adsorption on Fe(III)-chitosan and Fe(III)-chitosan-CTAB.

Natural polysaccharide-based biodegradable polymeric platforms for transdermal drug delivery system: a critical analysis

Natural biodegradable polymers generally include polysaccharides (starch, alginate, chitin/chitosan, hyaluronic acid derivatives, etc.) and proteins (collagen, gelatin, fibrin, etc.). In transdermal drug delivery systems (TDDS), these polymers play a vital role in controlling the device's drug release. It is possible that natural polymers can be used for TDDS to attain predetermined drug delivery rates due to their physicochemical properties. These polymers can be employed to market products and scale production because they are readily available and inexpensive. As a result of these polymers, new pharmaceutical delivery systems can be developed that is both regulated and targeted. The focus of this article is the application of a biodegradable polymeric platform based on natural polymers for TDDS. Due to their biocompatibility and biodegradability, natural biodegradable polymers are frequently used in biomedical applications. Additionally, these natural biodegradable polymers are being studied for their characteristics and behaviors.

Chitosan degradation products promote healing of burn wounds of rat skin

Burns can impair the barrier function of the skin, and small burns can also cause high mortality. The WHO has described that over 180,000 people die of burns worldwide each year. Thus, the treatment of burn wounds is a major clinical challenge. Chitooligosaccharides (COS) are alkaline amino oligosaccharides with small molecular weights obtained by enzyme or chemical degradation of chitosan. With the characteristics of biocompatibility, water solubility and degradability, it has attracted increasing attention in the fields of biomedicine. In the present study, we used COS to treat deep second-degree burn wounds of rat skin and found that COS was able to promote wound healing. We also revealed that COS could promote fibroblast proliferation. Transcriptome sequencing analysis was performed on COS-treated fibroblasts to identify the underlying mechanisms. The results showed that COS was able to promote wound healing through regulation of the mitogen-activated protein kinase (MAPK) pathway and growth factor Hepatocyte Growth Factor (HGF). Our results provide a potential drug for burn wound therapy and the related molecular mechanism.

Enhancement of Antimicrobial and Dyeing Properties of Cellulosic Fabrics via Chitosan Nanoparticles

The primary goal of this study is to prepare chitosan nanoparticles (CSNPs) by the ionic gelation method via the treatment of chitosan (0.2 wt.%) with tripolyphosphate (0.2 wt.%) ultrasonically for 45 min. FT-IR spectroscopy and TEM images were used to characterize and validate CSNP production. Cellulosic materials with different concentrations of CSNPs have better antibacterial and colouring characteristics. The treated cellulosic fabrics were analyzed by FT-IR spectroscopy, SEM, and thermogravimetric analysis. Colourimetric data measurements expressed in K/S values were used to evaluate the impact of CSNPs on the dyeing affinity of cellulosic materials. In addition, antibacterial activity against bacteria and fungi was tested on the treated cellulosic fabrics. According to the K/S values, cellulosic textiles treated with CSNPs (0.3 wt.%) had a better affinity for acid dyeing. These textiles also offer better antibacterial properties and are more resistant to washing, light, and rubbing. A cytotoxicity study found that CSNPs give cellulosic materials antibacterial and acid dyeing properties, which is good for the environment.

Novel 3D-Printed Dressings of Chitosan-Vanillin-Modified Chitosan Blends Loaded with Fluticasone Propionate for Treatment of Atopic Dermatitis

In the present study, the blends of CS and Vanillin-CS derivative (VACS) were utilized for the preparation of printable inks for their application in three-dimensional (3D) printing procedures. Despite the synergic interaction between the blends, the addition of ι-carrageenan (iCR) as a thickening agent was mandatory. Their viscosity analysis was conducted for the evaluation of the optimum CS/VACS ratio. The shear thinning behavior along with the effect of the temperature on viscosity values were evident. Further characterization of the 3D-printed structures was conducted. The effect of the CS/VACS ratio was established through swelling and contact angle measurements. An increasing amount of VACS resulted in lower swelling ability along with higher hydrophobicity. Fluticasone propionate (FLU), a crystalline synthetic corticosteroid, was loaded into the CS/VACS samples. The drug was loaded in its amorphous state, and consequently, its in vitro release was significantly enhanced. An initial burst release, followed by a sustained release profile, was observed.

Molecular Docking and Efficacy of Aloe vera Gel Based on Chitosan Nanoparticles against Helicobacter pylori and Its Antioxidant and Anti-Inflammatory Activities

The medicinal administration of Aloe vera gel has become promising in pharmaceutical and cosmetic applications particularly with the development of the nanotechnology concept. Nowadays, effective H. pylori treatment is a global problem; therefore, the development of natural products with nanopolymers such as chitosan nanoparticles (CSNPs) could represent a novel strategy for the treatment of gastric infection of H. pylori. HPLC analysis of A. vera gel indicated the presence of chlorogenic acid as the main constituent (1637.09 µg/mL) with other compounds pyrocatechol (1637.09 µg/mL), catechin (1552.92 µg/mL), naringenin (528.78 µg/mL), rutin (194.39 µg/mL), quercetin (295.25 µg/mL), and cinnamic acid (37.50 µg/mL). CSNPs and A. vera gel incorporated with CSNPs were examined via TEM, indicating mean sizes of 83.46 nm and 36.54 nm, respectively. FTIR spectra showed various and different functional groups in CSNPs, A. vera gel, and A. vera gel incorporated with CSNPs. Two strains of H. pylori were inhibited using A. vera gel with inhibition zones of 16 and 16.5 mm, while A. vera gel incorporated with CSNPs exhibited the highest inhibition zones of 28 and 30 nm with resistant and sensitive strains, respectively. The minimal inhibitory concentration (MIC) was 15.62 and 3.9 µg/mL, while the minimal bactericidal concentration (MBC) was 15.60 and 7.8 µg/mL with MBC/MIC 1 and 2 indexes using A. vera gel and A. vera gel incorporated with CSNPs, respectively, against the resistance strain. DPPH Scavenging (%) of the antioxidant activity exhibited an IC₅₀ of 138.82 μg/mL using A.vera gel extract, and 81.7 μg/mL when A.vera gel was incorporated with CSNPs. A.vera gel incorporated with CSNPs enhanced the hemolysis inhibition (%) compared to using A.vera gel alone. Molecular docking studies through the interaction of chlorogenic acid and pyrocatechol as the main components of A. vera gel and CSNPs with the crystal structure of the H. pylori (4HI0) protein supported the results of anti-H. pylori activity.

Role of chitosan in titanium coatings. trends and new generations of coatings

Survival studies of dental implants currently reach high figures. However, considering that the recipients are middle-aged individuals with associated pathologies, research is focused on achieving bioactive surfaces that ensure osseointegration. Chitosan is a biocompatible, degradable polysaccharide with antimicrobial and anti-inflammatory properties, capable of inducing increased growth and fixation of osteoblasts around chitosan-coated titanium. Certain chemical modifications to its structure have been shown to enhance its antibacterial activity and osteoinductive properties and it is generally believed that chitosan-coated dental implants may have enhanced osseointegration capabilities and are likely to become a commercial option in the future. Our review provided an overview of the current concepts and theories of osseointegration and current titanium dental implant surfaces and coatings, with a special focus on the in vivo investigation of chitosan-coated implants and a current perspective on the future of titanium dental implant coatings.

Lyophilic and Sorption Properties of Chitosan Aerogels Modified with Copolymers Based on Glycidyl Methacrylate and Alkyl Methacrylates

This paper discusses the influence of the structure of copolymers based on glycidyl methacrylate and alkyl methacrylates with C₆–C₁₈ hydrocarbon side groups on the wettability and sorption properties of surface-modified chitosan aerogels. The grafting of copolymers onto the surface of aerogels was confirmed by elemental analysis, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy. As a result of the modification, with an increase in the amount of the hydrocarbon substituent alkyl methacrylate, the surface of the resulting materials became hydrophobic with contact angles in the range of 146–157°. At the same time, the water absorption of the aerogels decreased by a factor of 30 compared to that for unmodified aerogels, while the sorption capacity for light oil, diesel fuel, and synthetic motor oil remained at the level of more than 30 g/g. Chitosan aerogels with grafted copolymers based on glycidyl methacrylate and alkyl methacrylates retain biodegradation capacity; however, compared to unmodified chitosan, this process has an induction period.

Chitosan: Sources, Processing and Modification Techniques

Chitosan, a copolymer of glucosamine and N-acetyl glucosamine, is derived from chitin. Chitin is found in cell walls of crustaceans, fungi, insects and in some algae, microorganisms, and some invertebrate animals. Chitosan is emerging as a very important raw material for the synthesis of a wide range of products used for food, medical, pharmaceutical, health care, agriculture, industry, and environmental pollution protection. This review, in line with the focus of this special issue, provides the reader with (1) an overview on different sources of chitin, (2) advances in techniques used to extract chitin and converting it into chitosan, (3) the importance of the inherent characteristics of the chitosan from different sources that makes them suitable for specific applications and, finally, (4) briefly summarizes ways of tailoring chitosan for specific applications. The review also presents the influence of the degree of acetylation (DA) and degree of deacetylation (DDA), molecular weight (M_w) on the physicochemical and biological properties of chitosan, acid-base behavior, biodegradability, solubility, reactivity, among many other properties that determine processability and suitability for specific applications. This is intended to help guide researchers select the right chitosan raw material for their specific applications.

Application Progress of Modified Chitosan and Its Composite Biomaterials for Bone Tissue Engineering

In recent years, bone tissue engineering (BTE), as a multidisciplinary field, has shown considerable promise in replacing traditional treatment modalities (i.e., autografts, allografts, and xenografts). Since bone is such a complex and dynamic structure, the construction of bone tissue composite materials has become an attractive strategy to guide bone growth and regeneration. Chitosan and its derivatives have been promising vehicles for BTE owing to their unique physical and chemical properties. With intrinsic physicochemical characteristics and closeness to the extracellular matrix of bones, chitosan-based composite scaffolds have been proved to be a promising candidate for providing successful bone regeneration and defect repair capacity. Advances in chitosan-based scaffolds for BTE have produced efficient and efficacious bio-properties via material structural design and different modifications. Efforts have been put into the modification of chitosan to overcome its limitations, including insolubility in water, faster depolymerization in the body, and blood incompatibility. Herein, we discuss the various modification methods of chitosan that expand its fields of application, which would pave the way for future applied research in biomedical innovation and regenerative medicine.

Recent advances of chitosan-based polymers in biomedical applications and environmental protection

Interest in polymer-based biomaterials such as chitosan and its modifications and also the methods of their application in various fields of science is uninterruptedly growing. Owing to unique physicochemical, biological, ecological, physiological properties, such as biocompatibility, biodegradability, stability in the natural environment, non-toxicity, high biological activity, economic affordability, chelating of metal ions, high sorption properties, chitosan is used in various biomedical and industrial processes. The reactivity of the amino and hydroxyl groups in the structure makes it more interesting for diverse applications in drug delivery, tissue engineering, wound healing, regenerative medicine, blood anticoagulation and bone, tendon or blood vessel engineering, dentistry, biotechnology, biosensing, cosmetics, water treatment, agriculture. Taking into account the current situation in the world with COVID-19 and other viruses, chitosan is also active in the form of a vaccine system, it can deliver antibodies to the nasal mucosa and load gene drugs that prevent or disrupt the replication of viral DNA/RNA, and deliver them to infected cells. The presented article is an overview of the nowaday state of the application of chitosan, based on literature of recent years, showing importance of fundamental and applied studies aimed to expand application of chitosan-based polymers in many fields of science.

Solution blow spinning of highly deacetylated chitosan nanofiber scaffolds for dermal wound healing

Biocompatible fibrous scaffolds based on highly deacetylated chitosan were fabricated using high-throughput solution blow spinning. Scanning electron microscopy analysis revealed that the chitosan nanofiber scaffolds had ultrafine and continuous fibers (300-1200 nm) with highly interconnected porous structures (30-75% porosity), mimicking some aspects of the native extracellular matrix in skin tissue. Post-treatment of as-spun nanofibers with aqueous potassium carbonate solution resulted in a fibrous scaffold with a high chitosan content that retained its fibrous structural integrity for cell culture. Analysis of the mechanical properties of the chitosan nanofiber scaffolds in both dry and wet conditions showed that their strength and durability were sufficient for wound dressing applications. Significantly, the wet scaffold underwent remarkable elastic deformation during stretch such that the elongation at break dramatically increased to up to 44% of its original length, showing wavy fiber morphology near the break site. The culture of normal human dermal fibroblast cells onto scaffolds for 1-14 days demonstrated that the scaffolds were highly compatible and a suitable platform for cell adhesion, viability, and proliferation. Secretion profiles of wound healing-related proteins to the cell culture medium demonstrated that chitosan fibers were a promising scaffold for wound healing applications. Overall, the dense fibrous network with high porosity of the chitosan nanofiber scaffold and their mechanical properties indicate that they could be used to design and fabricate new materials that mimic the epidermis layer of natural skin.

Development of Biocompatible Polyhydroxyalkanoate/Chitosan-Tungsten Disulphide Nanocomposite for Antibacterial and Biological Applications

The unique structures and multifunctionalities of two-dimensional (2D) nanomaterials, such as graphene, have aroused increasing interest in the construction of novel scaffolds for biomedical applications due to their biocompatible and antimicrobial abilities. These two-dimensional materials possess certain common features, such as high surface areas, low cytotoxicities, and higher antimicrobial activities. Designing suitable nanocomposites could reasonably improve therapeutics and reduce their adverse effects, both medically and environmentally. In this study, we synthesized a biocompatible nanocomposite polyhydroxyalkanoate, chitosan, and tungsten disulfide (PHA/Ch-WS₂). The nanocomposite PHA/Ch-WS₂ was characterized by FESEM, elemental mapping, FTIR, and TGA. The objective of this work was to investigate the antimicrobial activity of PHA/Ch-WS₂ nanocomposites through the time–kill method against the multi-drug-resistant model organisms Escherichia coli (E. coli) K1 and methicillin-resistant Staphylococcus aureus (MRSA). Further, we aimed to evaluate the cytotoxicity of the PHA/Ch-WS₂ nanocomposite using HaCaT cell lines by using a lactate dehydrogenase (LDH) assay. The results demonstrated very significant bactericidal effects of the PHA/Ch-WS₂ nanocomposite, and thus, we hypothesize that the nanocomposite would feasibly suit biomedical and sanitizing applications without causing any adverse hazard to the environment.

A review on super-wettable porous membranes and materials based on bio-polymeric chitosan for oil-water separation

Appropriate surface wettability of membranes and materials are of an extreme importance for targeting separation of mixtures/emulsions such as oil from water or conversely water from oil. The development of super-wettable membranes and materials surfaces have shown remarkable potential for recovering water from oil-water emulsion while offering maximum resistance to fouling. The availability of clean and potable water has been regarded as an important global challenge for coming human generations. Oil and gas industry is continuously producing immense quantities of waste stream regarded as produced water which contains oil dispersed in water along with other several components. Treating such immense quantities of oily wastewater is of utmost need for recovering precious water for possible reuse or safe disposal. Various technologies have been developed for targeting the separation of oil-water emulsions or mixtures to harness useful potable water and oil as products. Membrane-based separations or use of porous materials such as mesh have been explored in literature for separation of oil-water mixtures/emulsions. Given the unique features of special hydrophilicity, ease of tunability, control of molecular weight, abundant availability, and potential for commercial scale up, chitosan has been extensively used for modifying membranes/meshes or preparing composites with other materials for oil-water separations. This review has described in detail the synthesis, methods of modification and application of chitosan-based super-wettable membranes/meshes and porous materials for oil-water separation. The special wettability features including super-hydrophobicity/superoleophilicity, super-oleophobicity/super-hydrophilicity and super-hydrophilicity/underwater super-oleophobicity of various chitosan-based membranes and materials have been discussed in detail in the review. The strategies for enhancing or developing special wettability for target specific applications have also been discussed. Finally, the challenges, their respective importance have been identified along with a discussion on possible solutions to these challenges.

Nanostructured particles assembled from natural building blocks for advanced therapies

Advanced treatments based on immune system manipulation, gene transcription and regulation, specific organ and cell targeting, and/or photon energy conversion have emerged as promising therapeutic strategies against a range of challenging diseases. Naturally derived macromolecules (e.g., proteins, lipids, polysaccharides, and polyphenols) have increasingly found use as fundamental building blocks for nanostructured particles as their advantageous properties, including biocompatibility, biodegradability, inherent bioactivity, and diverse chemical properties make them suitable for advanced therapeutic applications. This review provides a timely and comprehensive summary of the use of a broad range of natural building blocks in the rapidly developing field of advanced therapeutics with insights specific to nanostructured particles. We focus on an up-to-date overview of the assembly of nanostructured particles using natural building blocks and summarize their key scientific and preclinical milestones for advanced therapies, including adoptive cell therapy, immunotherapy, gene therapy, active targeted drug delivery, photoacoustic therapy and imaging, photothermal therapy, and combinational therapy. A cross-comparison of the advantages and disadvantages of different natural building blocks are highlighted to elucidate the key design principles for such bio-derived nanoparticles toward improving their performance and adoption. Current challenges and future research directions are also discussed, which will accelerate our understanding of designing, engineering, and applying nanostructured particles for advanced therapies.

Engineered nasal dry powder for the encapsulation of bioactive compounds

In this review, we present the potential of nasal dry powders to deliver stable bioactive compounds and their manufacture using spray-drying (SD) techniques to achieve encapsulation. We also review currently approved and experimental excipients used for powder manufacturing for specific target drugs. Polymers, sugars, and amino acids are recommended for specific actions, such as mucoadhesive interactions, to increase residence time on the nasal mucosa; for example, high-molecular weight polymers, such as hydroxypropyl methylcellulose, or mannitol, which protect the bioactive compounds, increase their stability, and enhance drug absorption in the nasal mucosa; and leucine, which promotes particle formation and improves aerosol performance. Teaser: XXXX.

Current advances in cell therapeutics: A biomacromolecules application perspective

INTRODUCTION

Many chronic diseases have evolved and to circumvent the limitations of using conventional drug therapies, smart cell encapsulating delivery systems have been explored to customize the treatment with alignment to disease longevity. Cell therapeutics has advanced in tandem with improvements in biomaterials that can suitably deliver therapeutic cells to achieve targeted therapy. Among the promising biomacromolecules for cell delivery are those that share bio-relevant architecture with the extracellular matrix and display extraordinary compatibility in the presence of therapeutic cells. Interestingly, many biomacromolecules that fulfil these tenets occur naturally and can form hydrogels.

AREAS COVERED

This review provides a concise incursion into the paradigm shift to cell therapeutics using biomacromolecules. Advances in the design and use of biomacromolecules to assemble smart therapeutic cell carriers is discussed in light of their pivotal role in enhancing cell encapsulation and delivery. In addition, the principles that govern the application of cell therapeutics in diabetes, neuronal disorders, cancers and cardiovascular disease are outlined.

EXPERT OPINION

Cell therapeutics promises to revolutionize the treatment of various secretory cell dysfunctions. Current and future advances in designing functional biomacromolecules will be critical to ensure that optimal delivery of therapeutic cells is achieved with desired biosafety and potency.

Advances in Modification Methods Based on Biodegradable Membranes in Guided Bone/Tissue Regeneration: A Review

Guided tissue/bone regeneration (GTR/GBR) is commonly applied in dentistry to aid in the regeneration of bone/tissue at a defective location, where the assistive material eventually degrades to be substituted with newly produced tissue. Membranes separate the rapidly propagating soft tissue from the slow-growing bone tissue for optimal tissue regeneration results. A broad membrane exposure area, biocompatibility, hardness, ductility, cell occlusion, membrane void ratio, tissue integration, and clinical manageability are essential functional properties of a GTR/GBR membrane, although no single modern membrane conforms to all of the necessary characteristics. This review considers ongoing bone/tissue regeneration engineering research and the GTR/GBR materials described in this review fulfill all of the basic ISO requirements for human use, as determined through risk analysis and rigorous testing. Novel modified materials are in the early stages of development and could be classified as synthetic polymer membranes, biological extraction synthetic polymer membranes, or metal membranes. Cell attachment, proliferation, and subsequent tissue development are influenced by the physical features of GTR/GBR membrane materials, including pore size, porosity, and mechanical strength. According to the latest advances, key attributes of nanofillers introduced into a polymer matrix include suitable surface area, better mechanical capacity, and stability, which enhances cell adhesion, proliferation, and differentiation. Therefore, it is essential to construct a bionic membrane that satisfies the requirements for the mechanical barrier, the degradation rate, osteogenesis, and clinical operability.

Sprayable Hydrogel for Biomedical Applications

Polymeric hydrogels have extraordinary potential to be utilized for biomedical applications. Recently, sprayable hydrogels have received increasing attention for their biocompatibility, degradability, tunable mechanical properties and rapid spray-filming abilities. In...

Fabrication of chitin monoliths with controllable morphology by thermally induced phase separation of chemically modified chitin

As a natural polymer, chitin has excellent biological properties such as biodegradability and immunological, antibacterial, and wound-healing activities and has numerous applications in cosmetics, drug delivery, and pharmaceuticals. Organic polymer monoliths have also drawn significant attention, owing to their high permeability, large surface area, and high mechanical strength. They are usually applied to separation, ion exchange, catalysis, and chromatography. We have previously prepared cellulose monoliths using biopolymers; however, because chitin possesses amide groups on its side chain, it is superior to cellulose for further chemical modification and applications. However, the utilization of chitin is restricted by its insolubility in water and common organic solvents. In this study, for the first time, a monolith was prepared by chemical modification of chitin using a thermally induced phase separation (TIPS) method. First, we prepared dibutyrylchitin (DBC) as a starting polymer that is soluble in organic solvents. To prepare the monolith, DBC was dissolved completely in dimethyl sulfoxide (DMSO) while heating, and deionized water was added to the solution. It was then cooled at 20 °C to form a monolith via phase separation. The porous morphology of the DBC monolith was altered by regulating the DBC concentration, DMSO/H₂O ratio, and aging temperature. The DBC monolith was converted to a chitin monolith by the alkaline hydrolysis of butyryl ester. The successful hydrolysis of butyryl ester was confirmed by the disappearance of the peak at 1735 cm^-1 in the FT-IR spectra, which is related to the ester moiety of DBC. The chitin monolith has the potential to be utilized under water flow for catalysis, metal capture from wastewater, dye sorption, and drug delivery systems.

Recent progress, synthesis, and applications of chitosan-decorated magnetic nanocomposites in remediation of dye-laden wastewaters

Over the past several decades, the disposal of dyes from the industrial manufacturing sector has had an inadvertent impact on water ecology as polluted water bodies with these hazardous dyes...

Reversible Crosslinking of Polymer/Metal-Ion Complexes for a Microfluidic Switch

The importance of chitosan has been strongly emphasized in literature because this natural polymer could not only remove heavy metal ions in water but also have the potential for recyclability. However, reversible phase transition and its dynamics, which are highlighting areas of a recycle process, have not been studied sufficiently. Here, we present dynamic studies of the dissolution as well as the gelation of a physically crosslinked chitosan hydrogel. Specifically, a one-dimensional gel growth system and an acetate buffer solution were prepared for the precise analysis of the dominant factors affecting a phase transition. The dissolution rate was found to be regulated by three major factors of the pH level, Cu2+, and NO2 -, while the gelation rate was strongly governed by the concentration of OH-. Apart from the gelation rate, the use of Cu2+ led to the rapid realization of gel characteristics. The results here provide strategies for process engineering, ultimately to determine the phase-transition rates. In addition, a microfluidic switch was successfully operated based on a better understanding of the reversible crosslinking of the chitosan hydrogel. Rapid gelation was required to close the channel, and a quick switchover was achieved by a dissolution enhancement strategy. As a result, factors that regulated the rates of gelation or dissolution were found to be useful to operate the fluidic switch.

Alginate bone scaffolds coated with a bioactive lactose modified chitosan for human dental pulp stem cells proliferation and differentiation

Bioactive and biodegradable porous scaffolds can hasten the healing of bone defects; moreover, patient stem cells seeded onto scaffolds can enhance the osteoinductive and osteoconductive properties of these biomaterials. In this work, porous alginate/hydroxyapatite scaffolds were functionalized with a bioactive coating of a lactose-modified chitosan (CTL). The highly interconnected porous structure of the scaffold was homogeneously coated with CTL. The scaffolds showed remarkable stability up to 60 days of aging. Human Dental Pulp Stem Cells (hDPSCs) cultured in the presence of CTL diluted in culture medium, showed a slight and negligible increase in terms of proliferation rate; on the contrary, an effect on osteogenic differentiation of the cells was observed as a significant increase in alkaline phosphatase activity. hDPSCs showed higher cell adhesion on CTL-coated scaffolds than on uncoated ones. CTL coating did not affect cell proliferation, but stimulated cell differentiation as shown by alkaline phosphatase activity analysis.