Facile fabrication of functional hydrogels consisting of pullulan and polydopamine fibers for drug delivery

A chitosan-based light-curing hydrogel dressing for accelerated healing of infected wounds

Bacterial infections, excessive reactive oxygen species (ROS) accumulation and a persistent inflammatory response severely impede the wound healing process. In this study, we developed a novel multifunctional hydrogel dressing (LCPN) based on lipoic acid modified chitosan (LAMC), polypyrrole nanoparticles (PPy NPs) and nicotinamide mononucleotide (NMN) for accelerated healing of infected wounds. The synthesized LCPN hydrogel has several properties. Modification of lipoic acid significantly enhances the water solubility of chitosan making it easier to dissolve and absorb wound secretions. Interestingly, owing to the breaking and restructuring of disulfide bonds, LCPN hydrogel can be quickly bonded under UV light without relying on photoinitiators. In addition, the incorporation of PPy NPs not only enhances the electrical conductivity of LCPN hydrogel, but also confers photothermal antimicrobial capability to LCPN hydrogel. More importantly, the sustained release of NMN in LCPN hydrogel can significantly enhance cell proliferation, migration and antioxidant capacity, which is conducive to accelerated wound healing. In vitro and in vivo experiments have shown that LCPN hydrogel has excellent biocompatibility and the ability to promote wound healing. Therefore, the prepared multifunctional hydrogel is expected to be used as a novel dressing to accelerate wound healing.

A review of polysaccharide hydrogels as materials for skin repair and wound dressing: Construction, functionalization and challenges

Hydrogels can imitate the extracellular matrix, therefore facilitating the creation of an ideal healing environment for wounds. Consequently, they are popular as a material choice for wound dressings. Polysaccharides have been widely used in wound dressings due to their good biocompatibility and degradability. In this study, we first discuss skin and wound physiology before summarizing the methods for producing hydrogels from polysaccharides and their derivatized. These include not just normal polysaccharides like chitosan, cellulose, and alginate, but also Chinese medicinal polysaccharides with therapeutic properties. Then, strategies for causing hydrogel production from polysaccharides or their derivatives are briefly explained. Finally, the functions of hydrogel dressings are reviewed, including antibacterial, antioxidant, and adhesive properties, as well as the methods for achieving these properties. Furthermore, current issues and concerns are discussed, with the goal of providing fresh paths for the development of future wound dressings.

Facile synthesis of ATTM@ZIF-8 modified pullulan hydrogels for enhanced adsorption of Congo red and malachite green

Efficient capture of dyes from wastewater is of great importance for environmental remediation. Yet constructing adsorbents with satisfactory adsorption efficiency and low cost remains a major challenge. This work reports a simple and scalable method for the fabrication of functionalized porous pullulan hydrogel adsorbent decorated with ATTM@ZIF-8 for the adsorption of congo red (CR) and malachite green (MG). The embedding of ammonium tetrathiomolybdate (ATTM) into the ZIF-8 nanoclusters offered additional adsorption sites and enlarged the pore size of the resulting ATTM@ZIF-8. The homogeneous dispersion of the nanoparticles in the three-dimensional network of polysaccharide gels prevents their agglomeration and thus improves the affinity for dye molecules. The resulting adsorbent AZP-20 at optimized composite ratios exhibits high activity, selectivity, interference resistance, reusability and cytocompatibility in dye adsorption applications, and possesses high removal rate of dye in real water systems. Batch experiments demonstrated that the adsorption rate of AZP-20 for MG and CR was 1645.28 mg g-1 and 680.33 mg g-1, and would be influenced by pH conditions. Adsorption kinetics followed pseudo-second-order model. Adsorption isotherms followed Langmuir model for MG and Freundlich model for CR. The adsorption of dye molecules primarily relied on electrostatic interaction (MG) and π-π stacking interaction (CR). Conclusively, the prepared AZPs adsorbent illuminated good application prospects in the treatment of complex component dye wastewater.

Injectable and self-healing sulfated hyaluronic acid/gelatin hydrogel as dual drug delivery system for circumferential tracheal repair

Stem cell-based therapies show promise for clinically addressing circumferential tracheal defects (CTD) through tissue engineering. However, creating a tissue-engineered tracheal tube possesses a healthy cartilage matrix and intact tube structure remains a challenge. A solution lies in the use of an injectable hydrogel with shape adaptability and chondrogenic capacity, serving as a practical and dependable platform for tubular tracheal cartilage regeneration. In this study, we developed an injectable hydrogel using modified natural polymers-hydrazide-grafted gelatin (Gelatin-ADH) and aldehyde-modified hyaluronic acid with sulfated groups (HA-CHO-SO3) via Schiff Base interaction. Additionally, aldehyde-modified β-cyclodextrin (β-CD-CHO) was introduced into the network during hydrogel formation. The negative sulfated groups and hydrophobic cavities of β-cyclodextrin facilitated the efficient encapsulation and sustained release of transforming growth factor-β1 (TGF-β1) and kartogenin (KGN) within our hydrogel. This synergistically promoted the chondrogenesis of loaded bone marrow stem cells (BMSCs). Subsequently, we employed this TGF-β1, KGN, and BMSCs loaded hydrogel to form a cartilage ring. This ring was then assembled into an engineered tracheal cartilage tube using our previously reported ring-to-tube strategy. Our results demonstrated that the engineered tracheal cartilage tube effectively repaired CTD in a rabbit model. Hence, this study introduces a novel hydrogel with significant clinical application potential for tracheal tissue engineering.

Polydopamine Applications in Biomedicine and Environmental Science

This manuscript explores the multifaceted applications of polydopamine (PDA) across various scientific and industrial domains. It covers the chemical aspects of PDA and its potential in bone tissue engineering, implant enhancements, cancer treatment, and nanotechnology. The manuscript investigates PDA's roles in tissue engineering, cell culture technologies, surface modifications, drug delivery systems, and sensing techniques. Additionally, it highlights PDA's contributions to microfabrication, nanoengineering, and environmental applications. Through detailed testing and assessment, the study identifies limitations in PDA-related research, such as synthesis complexity, incomplete mechanistic understanding, and biocompatibility variability. It also proposes future research directions aimed at improving synthesis techniques, expanding biomedical applications, and enhancing sensing technologies to optimize PDA's efficacy and scalability.

Mimosa/quince seed mucilage-co-poly (methacrylate) hydrogels for controlled delivery of capecitabine: Simulation studies, characterization and toxicological evaluation

This research focused on developing pH-regulated intelligent networks using quince and mimosa seed mucilage through aqueous polymerization to sustain Capecitabine release while overcoming issues like short half-life, high dosing frequency, and low bioavailability. The resulting MSM/QSM-co-poly(MAA) hydrogel was evaluated for several parameters, including complex structure formation, stability, pH sensitivity, morphology, and elemental composition. FTIR, DSC, and TGA analyses confirmed the formation of a stable, complex cross-linked network, demonstrating excellent stability at elevated temperatures. SEM analysis revealed the hydrogels' smooth, fine texture with porous surfaces. PXRD and EDX results indicated the amorphous dispersion of Capecitabine within the network. The QMM9 formulation achieved an optimal Capecitabine loading of 87.17 %. The gel content of the developed formulations ranged from 65.21 % to 90.23 %. All formulations exhibited excellent swelling behavior, with ratios between 65.91 % and 91.93 % at alkaline pH. In vitro dissolution studies indicated that up to 98 % of Capecitabine was released after 24 h at pH 7.4, demonstrating the potential for sustained release. Furthermore, toxicological evaluation in healthy rabbits confirmed the system's safety, non-toxicity, and biocompatibility.

O-carboxymethyl chitosan in biomedicine: A review

O-carboxymethyl chitosan (O-CMC) is a chitosan derivative produced through the substitution of hydroxyl (-OH) functional groups in glucosamine units with carboxymethyl (-CH2COOH) substituents, effectively addressing the inherent solubility issues of chitosan in aqueous solutions. O-CMC has garnered significant interest due to its enhanced solubility, elevated viscosity, minimal toxicity, and advantageous biocompatibility properties. Furthermore, O-CMC demonstrates antibacterial, antifungal, and antioxidant characteristics, rendering it a promising candidate for various biomedical uses such as wound healing, tissue engineering, anti-tumor therapies, biosensors, and bioimaging. Additionally, O-CMC is well-suited for the fabrication of nanoparticles, hydrogels, films, microcapsules, and tablets, offering opportunities for effective drug delivery systems. This review outlines the distinctive features of O-CMC, offers analyses of advancements and future potential based on current research, examines significant obstacles for clinical implementation, and foresees its ongoing significant impacts in the realm of biomedicine.

Carbene-mediated gelatin and hyaluronic acid hydrogel paints with ultra adhesive ability for arthroscopic cartilage repair

In articular cartilage defect, particularly in arthroscopy, regenerative hydrogels are urgently needed. It should be able to firmly adhere to the cartilage tissue and maintain sufficient mechanical strength to withstand approximately 10 kPa of arthroscopic hydraulic flushing. In this study, we report a carbene-mediated ultra adhesive hybrid hydrogel paints for arthroscopic cartilage repair, which combined the photo initiation of double crosslinking system with the addition of diatomite, as a further reinforcing agent and biological inorganic substances. The double network consisting of ultraviolet initiated polymerization of hyaluronic acid methacrylate (HAMA) and carbene insertion chemistry of diazirine-grafted gelatin (GelDA) formed an ultra-strong adhesive hydrogel paint (H2G5DE). Diatomite helped the H2G5DE hydrogel paint firmly adhere to the cartilage defect, withstanding nearly 100 kPa of hydraulic pressure, almost 10 times that in clinical arthroscopy. Furthermore, the H2G5DE hydrogel supported cell growth, proliferation, and migration, thus successfully repairing cartilage defects. Overall, this study demonstrates a proof-of-concept of ultra-adhesive polysaccharide hydrogel paints, which can firmly adhere to the articular cartilage defects, can resist continuous hydraulic pressure, can promote effective cartilage regeneration, and is very suitable for minimally invasive arthroscopy.

Janus structure hydrogels: recent advances in synthetic strategies, biomedical microstructure and (bio)applications

Janus structure hydrogels (JSHs) are novel materials. Their primary fabrication methods and various applications have been widely reported. JSHs are primarily composed of Janus particles (JNPs) and polysaccharide components. They exhibit two distinct physical or chemical properties, generating intriguing characteristics due to their asymmetric structure. Normally, one side (adhesive interface) is predominantly constituted of polysaccharide components, primarily serving excellent adhesion. On the other side (functional surface), they integrate diverse functionalities, concurrently performing a plethora of synergistic functions. In the biomedical field, JSHs are widely applied in anti-adhesion, drug delivery, wound healing, and other areas. It also exhibits functions in seawater desalination and motion sensing. Thus, JSHs hold broad prospects for applications, and they possess significant research value in nanotechnology, environmental science, healthcare, and other fields. Additionally, this article proposes the challenges and future work facing these fields.

Structural identification and anti-neuroinflammatory effect of a heteropolysaccharide ATP50-3 from Acorus tatarinowii rhizome

Acorus tatarinowii, a famous traditional Chinese medicine, is used for the clinical treatment of memory impairment and dementia. In this research, AT50, the crude polysaccharide extracted from A. tatarinowii rhizome, significantly improved the memory and learning ability of mice with Alzheimer's disease (AD) and exerted excellent anti-neuroinflammatory effects. More importantly, AT50 returned the levels of NO, TNF-α, IL-1β, PGE-2, and IL-6 in AD mouse brains to normal levels. To identify the active ingredients in AT50, a heteropolysaccharide ATP50-3 was obtained from AT50. Structural analysis indicated ATP50-3 consisted of α-L-Araf-(1→, →2)-α-L-Araf-(1→, →3)-α-L-Araf-(1→, →5)-α-L-Araf-(1→, α-D-Xylp-(1→, →3,4)-β-D-Xylp-(1→, →3)-α-D-Galp-(1→, →3,6)-α-D-Galp-(1→, →6)-4-OAc-α-D-Galp-(1→, →3,4,6)-α-D-Galp-(1→, →4)-α-D-Glcp-(1→, →2,3,6)-β-D-Glcp-(1→, →4,6)-α-D-Manp-(1→, →3,4)-α-L-Rhap-(1→, →4)-α-D-GalpA-(1→, and →4)-α-D-GlcpA-(1 → residues and terminated with Xyl and Ara. Additionally, ATP50-3 significantly inhibited the release of proinflammatory factors in lipopolysaccharide-stimulated BV2 cells. ATP50-3 may be an active constituent of AT50, responsible for its anti-neuroinflammatory effects, with great potential to treat AD.

Evaluation of physiochemical and biomedical properties of psyllium-poly(vinyl phosphonic acid-co-acrylamide)-cl-N,N-methylene bis acrylamide based hydrogels

Present investigation deals with the synthesis of psyllium based copolymeric hydrogels and evaluation of their physiochemical and biomedical properties. These copolymers have been prepared by grafting of poly(vinyl phosphonic acid) (poly (VPA)) and poly(acrylamide) (poly(AAm)) onto psyllium in the presence of crosslinker N,N-methylene bis acrylamide (NNMBA). These copolymers [psyllium-poly(VPA-co-AAm)-cl-NNMBA] were characterized by field emission-scanning electron micrographs (FE-SEM), electron dispersion X-ray analysis (EDAX), Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), 13C-nuclear magnetic resonance (NMR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA)- differential thermal analysis (DTG). FESEM, AFM and XRD demonstrated heterogeneous morphology with a rough surface and an amorphous nature. Diffusion of ornidazole occurred with a non-Fickian diffusion mechanism, and the release profile data was fitted in the Korsemeyer-Peppas kinetic model. Biochemical analysis of hydrogel properties confirmed the blood-compatible nature during blood-polymer interactions and revealed haemolysis value 3.95 ± 0.05 %. The hydrogels exhibited mucoadhesive character during biomembrane-polymer interactions and demonstrated detachment force = 99.0 ± 0.016 mN. During 2,2-diphenyl-1-picrylhydrazyl reagent (DPPH) assay, free radical scavenging was observed 37.83 ± 3.64 % which illustrated antioxidant properties of hydrogels. Physiological and biomedical properties revealed that these hydrogels could be explored for drug delivery uses.

A dual catalytic functionalized hollow mesoporous silica-based nanocarrier coated with bacteria-derived exopolysaccharides for targeted delivery of irinotecan to colorectal cancer cells

In this study, we introduced a multifunctional hollow mesoporous silica-based nanocarrier (HMSN) for the targeted delivery of irinotecan (IRT) to colorectal cancer cells. Due to their large reservoirs, hollow mesoporous silica nanoparticles are suitable platforms for loading significant amounts of drugs for sustained drug release. To respond to pH and redox, HMSNs were functionalized with cerium and iron oxides. Additionally, they were coated with bacterial-derived exopolysaccharide (EPS) as a biocompatible polymer. In vitro analyses revealed that cytotoxicity induced in cancer cells through oxidative stress, mediated by mature nanocarriers (EPS.IRT.Ce/Fe.HMSN), was surprisingly greater than that caused by free drugs. Cerium and iron ions, in synergy with the drug, were found to generate reactive oxygen species when targeting the acidic pH within lysosomes and the tumor microenvironment. This, in turn, triggered cascade reactions, leading to cell death. In vivo experiments revealed that the proposed nanocarriers had no noticeable effect on healthy tissues. These findings indicate the selective delivery of the drug to cancerous tissue and the induction of antioxidant effects due to the dual catalytic properties of cerium in normal cells. Accordingly, this hybrid drug delivery system provides a more effective treatment for colorectal cancer with the potential for cost-effective scaling up.

ZnO-incorporated alginate assemblies: Tunable pH-responsiveness and improved drug delivery for cancer therapy

Delivering drugs selectively to tumor tissues is a significant challenge in cancer therapy, and pH-responsive polymeric assemblies have shown great potential in achieving this goal. In this study, we developed a pH-responsive alginate-based assemblies, called (amine-modified ZnO)-oxidized alginate-PEG ((ZnO-N)-OAl-PEG), for selective drug delivery in cancer treatment. The incorporation of ZnO-N nanoparticles into the alginate-based assemblies enables pH-responsiveness and maintains stability under physiological conditions. At an acidic pH, (ZnO-N)-OAl-PEG disassembles due to the conversion of ZnO to Zn2+, which triggers the unloading of doxorubicin (DOX) from the imine bond between DOX and alginate. This unloading results in the death of cancer cells and inhibition of tumor growth. The anticancer efficacy of (DOX/ZnO-N)-OAl-PEG was demonstrated in vitro and in vivo, providing promising prospects for cancer treatment based on ZnO-induced pH-responsiveness. These findings may also inspire the development of advanced drug delivery systems (DDSs) for cancer therapy.

Quince seed mucilage/β-cyclodextrin/Mmt-Na+-co-poly (methacrylate) based pH-sensitive polymeric carriers for controlled delivery of Capecitabine

In current work, quince seed mucilage and β-Cyclodextrin based pH regulated hydrogels were developed using aqueous free radical polymerization to sustain Capecitabine release patterns and to overcome its drawbacks, such as high dose frequency, short half-life, and low bioavailability. Developed networks were subjected to thermal analysis, Fourier transforms infrared spectroscopy, powder x-ray diffraction, elemental analysis, scanning electron microscopy, equilibrium swelling, and in-vitro release investigations to assess the network system's stability, complexation, morphology, and pH responsiveness. Thermally stable pH-responsive cross-linked networks were formed. Nanocomposite hydrogels were prepared by incorporating Capecitabine-containing clay into the swollen hydrogels. All the formulations exhibited equilibrium swelling ranging from 67.98 % to 92.98 % at pH 7.4. Optimum Capecitabine loading (88.17 %) was noted in the case of hydrogels, while it was 74.27 % in nanocomposite hydrogels. Excellent gel content (65.88 %-93.56 %) was noticed among developed formulations. Elemental analysis ensured the successful incorporation of Capecitabine. Nanocomposite hydrogels released 80.02 % longer than hydrogels after 30 h. NC hydrogels had higher t1/2 (10.57 h), AUC (121.52 μg.h/ml), and MRT (18.95 h) than hydrogels in oral pharmacokinetics. These findings imply that the pH-responsive carrier system may improve Capecitabine efficacy and reduce dosing frequency in cancer therapy. Toxicity profiling proved the system's safety, non-toxicity, and biocompatibility.

Regulate structure and properties of κ-carrageenan/konjac glucomannan composite hydrogel by filling effects of Quillaja saponin-stabilized solid lipid nanostructure

κ-Carrageenan/konjac glucomannan (κ-CA/KGM) composite hydrogels often fail to meet industrial requirements due to their low gel strength and poor mechanical properties, while solid lipid nanoparticles are potential materials to address this challenge due to their good biocompatibility. In the study, we propose using Quillaja saponin-stabilized solid lipid nanoparticle (QSLN) as nanofillers to enhance properties of κ-carrageenan/konjac glucan (κ-CA/KGM) composite hydrogels, and with emphasis on the effect of QSLN filling concentration on the structure and properties of composite hydrogels and the possible mechanisms were investigated. The best performance of QSLN-filled composite hydrogels was achieved at the QSLN concentration of 2.4 %. QSLN was uniformly distributed in the hydrogel matrix and formed electrostatic interactions and hydrogen bonding interactions with the matrix at an appropriate filling level, which enhanced the textural and rheological properties of the hydrogel greatly. In addition, the results of low-field NMR experiments showed that the filling of QSLN reduced the water mobility by enhancing the entanglement of polymer chains in the hydrogel matrix, which improved the freeze-thaw stability and regulated the swelling and deswelling behavior of the composite hydrogel. However, with the increasing of QSLN filling concentration, the above improvements were weakened by the depletion of van der Waals interactions due to the large amount of QSLN aggregation and the weakening of electrostatic interaction. In turn, the hydrogel was found to modulate the crystalline behavior of QSLN by X-ray diffraction and differential scanning calorimeter monitoring. Overall, the optimal synergistic effect between structure and properties could be achieved when the QSLN filling concentration was 2.4 %. These results provide a basis for the development of products that require excellent gel properties and structure.

Evaluation of the Effect of an Intraperitoneal Cytostatic-Loaded Supramolecular Hydrogel on Intestinal Anastomotic Healing in an Animal Model

The prognosis of colorectal cancer patients with peritoneal metastases is very poor. Intraperitoneal drug delivery systems, like supramolecular hydrogels, are being developed to improve local delivery and intraperitoneal residence time of a cytostatic such as mitomycin C (MMC). In this study, we evaluate the effect of intraperitoneal hydrogel administration on anastomotic healing. Forty-two healthy Wistar rats received a colonic end-to-end anastomosis, after which 6 animals received an intraperitoneal injection with saline, 18 with unloaded hydrogel and 18 with MMC-loaded hydrogel. After 7 days, animals were euthanized, and the anastomotic adhesion and leakage score were measured as primary outcome. Secondary outcomes were bursting pressure, histological anastomosis evaluation and body weight changes. Twenty-two rats completed the follow-up period (saline: n = 6, unloaded hydrogel: n = 10, MMC-loaded hydrogel: n = 6) and were included in the analysis. A trend towards significance was found for anastomotic leakage score between the rats receiving saline and unloaded hydrogel after multiple-comparison correction (p = 0.020, α = 0.0167). No significant differences were found for all other outcomes. The main reason for drop-out in this study was intestinal blood loss. Although the preliminary results suggest that MMC-loaded or unloaded hydrogel does not influence anastomotic healing, the intestinal blood loss observed in a considerable number of animals receiving unloaded and MMC-loaded hydrogel implies that the injection of the hydrogel under the studied conditions is not safe in the current rodent model and warrants further optimalisation of the hydrogel.

A phellinus igniarius polysaccharide/chitosan-arginine hydrogel for promoting diabetic wound healing

Inadequate angiogenesis and inflammation at the wound site have always been a major threat to skin wounds, especially for diabetic wounds that are difficult to heal. Therefore, hydrogel dressings with angiogenesis and antibacterial properties are very necessary in practical applications. This study reported a hydrogel (PCA) based on L-arginine conjugated chitosan (CA) and aldehyde functionalized polysaccharides of Phellinus igniarius (OPPI) as an antibacterial and pro-angiogenesis dressing for wound repair in diabetes for the first time. and discussed its possible mechanism for promoting wound healing. The results showed that PCA had good antioxidant, antibacterial, biological safety and other characteristics, and effectively promoted the healing course of diabetic wound model. In detail, the H&E and Masson staining results showed that PCA promoted normal epithelial formation and collagen deposition. The Western blot results confirmed that PCA decreased the inflammation by inhibiting the IKBα/NF-κB signaling pathway and enhanced angiogenesis by adjusting the level of HIF-1α. In conclusion, PCA is a promising candidate for promoting wound healing in diabetes. Graphic abstract.

Cationic starch: A functionalized polysaccharide based polymer for advancement of drug delivery and health care system - A review

Research and development in health care industry is in persistence progression. To make it more patient-friendly or to get maximum benefits from it, special attention to different advanced drug delivery system (ADDS) is employed that delivers the drug at the target site and will be able to sustain/control release of drugs. ADDS should be non-toxic, biodegradable, biocompatible along with desirable showing physicochemical and functional properties. These drug delivery systems can be totally based on polymers, either with natural or synthetic polymers. The molecular weight of polymer can be tuned and different groups of polymers can be modified or substituted with other functional groups. Degree of substitution is also tailored. Cationic starch in recent years is exploited in drug delivery, tissue engineering and biomedicine. Due to their abundant availability, low cost, easy chemical modification, low toxicity, biodegradability and biocompatibility, extensive research is now being carried out. Our present discussion will shed light on the usage of cationic starch in health care system.

Advance in Morchella sp. polysaccharides: Isolation, structural characterization and structure-activity relationship: A review

Morchella sp. is a kind of precious medicinal and edible fungus with a unique flavor and is rich in various amino acids and organic germanium needed by the human body. Most notably, Morchella sp. polysaccharides have attracted widespread attention due to their significant bioactivity in recent years. At present, extensive studies have been carried out on the extraction methods, structural characterization and activity evaluation of Morchella sp. polysaccharides, which provides a good theoretical basis for its further development and application. However, the systematic summary of the related research of Morchella sp. polysaccharides has not been reported yet. Therefore, this review mainly focused on the isolation and purification methods, structural characterization, biological activities and structure-activity relationship of Morchella sp. polysaccharides. This work will help to have a better in-depth understanding of Morchella sp. polysaccharides and provide a scientific basis and direct reference for more scientific and rational applications.

Photocatalytic Activity and Thermal Stability of Hybrid Metal-Polymer-Coordinated Complexes Derived from Gallic Acid and Ethylenediamine

Three new hybrid metal-polymer-coordinated complexes (MPCs) of copper(II), cobalt(II), and nickel(II) ions with an organic polymer derived from gallic acid and ethylenediamine (GAEtH) were synthesized. The structures of GAEtH and MPCs were characterized with FT-IR, ultraviolet (UV)-Vis, 1H and 13C NMR spectroscopy, and elemental and thermogravimetric analysis. The results reveal that the organic polymer GAEtH exhibits an infinite one-dimensional chain structure, while the hybrid MPCs have a double chain structure, with the two chains joined by metal ions. The thermodynamic and kinetic parameters of the thermal degradation stages were determined by the Coats Redfern method, and the photocatalytic behaviors of the MPCs were investigated through the decomposition of methyl orange dye under UV irradiation.

Oral insulin delivery: Barriers, strategies, and formulation approaches: A comprehensive review

Diabetes Mellitus is characterized by a hyperglycemic condition which can either be caused by the destruction of the beta cells or by the resistance developed against insulin in the cells. Insulin is a peptide hormone that regulates the metabolism of carbohydrates, proteins, and fats. Type 1 Diabetes Mellitus needs the use of Insulin for efficient management. However invasive methods of administration may lead to reduced adherence by the patients. Hence there is a need for a non-invasive method of administration. Oral Insulin has several merits over the conventional method including patient compliance, and reduced cost, and it also mimics endogenous insulin and hence reaches the liver by the portal vein at a higher concentration and thereby showing improved efficiency. However oral Insulin must pass through several barriers in the gastrointestinal tract. Some strategies that could be utilized to bypass these barriers include the use of permeation enhancers, absorption enhancers, use of suitable polymers, use of suitable carriers, and other agents. Several formulation types have been explored for the oral delivery of Insulin like hydrogels, capsules, tablets, and patches which have been described briefly by the article. A lot of attempts have been made for developing oral insulin delivery however none of them have been commercialized due to numerous shortcomings. Currently, there are several formulations from the companies that are still in the clinical phase, the success or failure of some is yet to be seen in the future.

Diversity of Bioinspired Hydrogels: From Structure to Applications

Hydrogels are three-dimensional networks with a variety of structures and functions that have a remarkable ability to absorb huge amounts of water or biological fluids. They can incorporate active compounds and release them in a controlled manner. Hydrogels can also be designed to be sensitive to external stimuli: temperature, pH, ionic strength, electrical or magnetic stimuli, specific molecules, etc. Alternative methods for the development of various hydrogels have been outlined in the literature over time. Some hydrogels are toxic and therefore are avoided when obtaining biomaterials, pharmaceuticals, or therapeutic products. Nature is a permanent source of inspiration for new structures and new functionalities of more and more competitive materials. Natural compounds present a series of physico-chemical and biological characteristics suitable for biomaterials, such as biocompatibility, antimicrobial properties, biodegradability, and nontoxicity. Thus, they can generate microenvironments comparable to the intracellular or extracellular matrices in the human body. This paper discusses the main advantages of the presence of biomolecules (polysaccharides, proteins, and polypeptides) in hydrogels. Structural aspects induced by natural compounds and their specific properties are emphasized. The most suitable applications will be highlighted, including drug delivery, self-healing materials for regenerative medicine, cell culture, wound dressings, 3D bioprinting, foods, etc.

Development, Optimization, and In Vitro/In Vivo Evaluation of Azelaic Acid Transethosomal Gel for Antidermatophyte Activity

Treatment of dermatophytosis is quite challenging. This work aims to investigate the antidermatophyte action of Azelaic acid (AzA) and evaluate its efficacy upon entrapment into transethosomes (TEs) and incorporation into a gel to enhance its application. Optimization of formulation variables of TEs was carried out after preparation using the thin film hydration technique. The antidermatophyte activity of AzA-TEs was first evaluated in vitro. In addition, two guinea pig infection models with Trichophyton (T.) mentagrophytes and Microsporum (M.) canis were established for the in vivo assessment. The optimized formula showed a mean particle size of 219.8 ± 4.7 nm and a zeta potential of -36.5 ± 0.73 mV, while the entrapment efficiency value was 81.9 ± 1.4%. Moreover, the ex vivo permeation study showed enhanced skin penetration for the AzA-TEs (3056 µg/cm²) compared to the free AzA (590 µg/cm²) after 48 h. AzA-TEs induced a greater inhibition in vitro on the tested dermatophyte species than free AzA (MIC₉₀ was 0.01% vs. 0.32% for T. rubrum and 0.032% for T. mentagrophytes and M. canis vs. 0.56%). The mycological cure rate was improved in all treated groups, specially for our optimized AzA-TEs formula in the T. mentagrophytes model, in which it reached 83% in this treated group, while it was 66.76% in the itraconazole and free AzA treated groups. Significant (p < 0.05) lower scores of erythema, scales, and alopecia were observed in the treated groups in comparison with the untreated control and plain groups. In essence, the TEs could be a promising carrier for AzA delivery into deeper skin layers with enhanced antidermatophyte activity.

A self-gelling powder based on polyacrylic acid/polyacrylamide/quaternate chitosan for rapid hemostasis

In order to improve the hemostatic effect of the hemostatic dressing for non-compressible wounds, unknown bleeding points and irregularly shaped wounds, a self-gelling hemostasis powder based on polyacrylic acid/polyacrylamide/quaternate chitosan (PAA/PAM/QCS) is prepared in this study. When in contact with water, the PAA/PAM/QCS can fuse and rapidly form a stable hydrogel in a short time (< 0.25 min). The PAA/PAM ratio is the main parameter that modulates the formation of the self-gel. The PAA/PAM self-gel can be formed only when the PAA/PAM ratio is 5:5, and the introduction of QCS does not influence the self-gelling behaviors and hydrogel stability. Moreover, the PAA/PAM/QCS self-gel shows good adhesive properties on wet tissue surfaces. In addition, the introduction of QCS improves the antibacterial activity of the self-gelling hemostasis powder. Furthermore, the prepared PAA/PAM/QCS powder can rapidly adsorb lots of blood, aggregate blood cells and platelets. The hemostatic results in vivo show that PAA/PAM/QCS powder is superior to the control group and commercial product groups (chitosan powder) with performance similar to hemostatic zeolite in terms of the amount of bleeding and hemostatic time. Therefore, the PAA/PAM/QCS self-gelling powder shows great application prospects for rapid hemostasis.

Double network microcrystalline cellulose hydrogels with high mechanical strength and biocompatibility for cartilage tissue engineering scaffold

Cartilage tissue regeneration is tremendously tough, it has become a major clinical challenge for the orthopedic medical community. Because of their bionic structure, high water content, biocompatibility, and biodegradability, hydrogels derived from natural polysaccharide are excellent candidates for cartilage tissue engineering. However, these materials often face problems such as poor mechanical strength and excessive swelling, which limit their clinical application. This study used a chemical-physical multi-step cross-linking strategy to create double-network (DN) microcrystalline cellulose (MCC) hydrogels. The hydrogels' intrinsic biomimetic macroporous shape and high water content made them ideal for chondrocyte adhesion and proliferation. The performance requirements for cartilage tissue engineering scaffolds are met by DN hydrogels, which have a sufficiently high compressive strength (4.53 MPa), superior compression recovery, and fatigue resistance, compared to single-network (SN) hydrogels. According to in vitro findings, DN hydrogels could boost cell adhesion and proliferation due to their safe and non-toxic nature. Hydrogels were demonstrated to be stable over the long-term performance, to degrade slowly, and to have strong histocompatibility by in vivo implantation. To construct cartilage tissue engineering scaffold and conduct three-dimensional cell culture, DN hydrogels have significant potential.

New approaches for enhancing the photosensitivity, antibacterial activity, and controlled release behavior of non-porous silica-titania nanoplatforms

This research presents a new approach for the synthesis of inorganic nano-platforms containing >2 layers. Nano-platforms were characterized using scanning electron microscopy, X-ray diffraction, fluorescence and Fourier transform infrared spectroscopy, fluorescence microscopy, dynamic light scattering, thermogravimetric analysis, Brunauer-Emmett-Teller, etc. Since it has been reported that the maximum tolerable dose of non-porous silica nanoparticles (NPs) in in-vivo studies is higher than that of mesoporous silica, the non-porous silica was prepared. Curcumin (CUR) was trapped between the surfaces of the spherical non-porous silica and titania NPs (<100 nm) as both fluorescent and therapeutic agents, thus resulting in increased loading capacity of the non-porous silica NPs, as well as providing significant photosensitivity, antibacterial activity, and controlled release. In addition, the surface of NPs was enriched with Methyl violet-10B (MV-10B), and Rhodamine B (RhB). Silica@CUR@titania exhibited approximately 9-fold higher fluorescence intensity than silica@CUR NPs. This finding enabled us to design nano-platforms with minimum toxic effect due to low contents of RhB for bioimaging applications. The antimicrobial efficiency of nano-platforms was evaluated against P. aeruginosa, E. coli, S. typhimurium, K. pneumonia, S. epidermidis, S. aureus, B. subtilis, B. cereus, and E. faecalis. It was concluded that titania markedly lowered the minimum inhibitory concentration values (MICs) of CUR against all bacteria except B. subtilis and P. aeruginosa. Theoretical simulation was also performed to clarify the accumulation of functionalized NPs in tumor tissue.

A novel micropattern platform constructed by TiO2 oxidation of PDA

Dopamine is a small molecule inspired by the dopamine motif of mussel foot proteins, and PDA is formed by the self-polymerization of dopamine. Under the UV-irradiation，PDA would be oxidized by reactive oxygen species (ROS) which were produced by photocatalytic reactions on TiO₂ surfaces，thus regulating the adhesion behavior of endothelial cells (ECs) TiO₂ inhibited platelet (Plt) adhesion after UV exposure. Polydopamine (PDA)-TiO₂ micropatterns (P-PDA-TiO₂) were prepared by magnetron sputtering and photolithography. This micropatterns successfully achieves selective adhesion of Plt and ECs. The selective adhesion of ECs disappears after vacuum reduction. In contrast to conventional cell patterning strategies, P-PDA-TiO₂ can easily achieve pattern separation of ECs and Plts and provide a new concept for building complex blood-contacting devices.

Chitosan-based multifunctional hydrogel for sequential wound inflammation elimination, infection inhibition, and wound healing

In this study, a composite hydrogel (QMPD hydrogel) composed of methacrylate anhydride (MA) grafted quaternary ammonium chitosan (QCS-MA), polyvinylpyrrolidone (PVP), and dopamine (DA) was designed for the sequential wound inflammation elimination, infection inhibition, and wound healing. The QMPD hydrogel formation was initiated by the ultraviolet light-triggered polymerization of QCS-MA. Furthermore, hydrogen bonds, electrostatic interactions, and "π-π" stacking between QCS-MA, PVP, and DA were involved in the hydrogel formation. In this hydrogel, the quaternary ammonium groups of quaternary ammonium chitosan and the photothermal conversion of polydopamine are capable of killing bacteria on wounds, which showed the bacteriostatic ratios of 85.6 % and 92.5 % toward Escherichia coli and Staphylococcus aureus, respectively. Moreover, the oxidation of DA sufficiently scavenged free radicals and introduced the QMPD hydrogel with good anti-oxidant and anti-inflammatory abilities. Together with the extracellular matrix-mimic tropical structure, the QMPD hydrogel significantly promoted the wound management of mice. Therefore, the QMPD hydrogel is expected to provide a new method for the design of wound healing dressings.

Injectable hybrid hydrogels physically crosslinked based on carrageenan and green graphene for tissue repair

Injectable and biocompatible novel hybrid hydrogels based on physically crosslinked natural biopolymers and green graphene for potential use in tissue engineering are reported. Kappa and iota carrageenan, locust bean gum and gelatin are used as biopolymeric matrix. The effect of green graphene content on the swelling behavior, mechanical properties and biocompatibility of the hybrid hydrogels is investigated. The hybrid hydrogels present a porous network with three-dimensionally interconnected microstructures, with lower pore size than that of the hydrogel without graphene. The addition of graphene into the biopolymeric network improves the stability and the mechanical properties of the hydrogels in phosphate buffer saline solution at 37 °C without noticeable change in the injectability. The mechanical properties of the hybrid hydrogels were enhanced by varying the dosage of graphene between 0.025 and 0.075 w/v%. In this range, the hybrid hydrogels preserve their integrity during mechanical test and recover the initial shape after removing the applied stress. Meanwhile, hybrid hydrogels with graphene content of up to 0.05 w/v% exhibit good biocompatibility for 3T3-L1 fibroblasts; the cells proliferate inside the gel structure and show higher spreading after 48 h. These injectable hybrid hydrogels with graphene have promising future as materials for tissue repair.

A pH responsive and superporous biocomposite hydrogel of Salvia spinosa polysaccharide-co-methacrylic acid for intelligent drug delivery

Herein, a drug delivery system (SSH-co-MAA) based on the mucilage from seeds of Salvia spinosa (SSH; polymer) and methacrylic acid (MAA; monomer) is introduced for the controlled delivery of venlafaxine HCl using a sustainable chemical approach. The optimized conditions for the designing of the ideal formulation (M4) of SSH-co-MAA were found to be 2.5% (w/w) of SSH, 30.0% (w/w) of MAA, 0.4% (w/w) of both N,N'-methylene-bis-acrylamide (MBA; cross-linker) and potassium persulfate (KPS; initiator). The structure characterization of SSH-co-MAA by Fourier transform infrared and solid-state CP/MAS ¹³C-NMR spectroscopy has confirmed the grafting of MAA onto SSH. The thermogravimetric analysis revealed that SSH-co-MAA is a stable entity before and after loading of the venlafaxine HCl-loaded SSH-co-MAA (VSSH-co-MAA). Scanning electron microscopy images of SSH-co-MAA after swelling then freeze drying showed the superporous nature of the hydrogel. The gel fraction (%) of SSH-co-MAA depended upon concentration of SSH, MAA, and MBA. The porosity (%) was increased with the increase in the concentration of SSH and decreased with the decrease in the concentration of MAA and MBA. The swelling indices, venlafaxine HCl loading, and release (24 h at the pH of the gastrointestinal tract) from VSSH-co-MAA were found to be dependent on the pH of the swelling media and the concentration of SSH, MAA, and MBA. The release of venlafaxine HCl followed non-Fickian diffusion mechanism. Conclusively, SSH-co-MAA is a novel material for potential application in targeted drug delivery applications.

Dopamine and DNA functionalized manganese whitlockite nanocrystals for magnetic resonance imaging and chemo-photothermal therapy of tumors

Multifunctional inorganic nanomaterials have opened new avenues for cancer diagnosis and therapy. However, the difficulty to functionalize them has prevented their wider application, owing to the lack of active groups on their surfaces. Here we report a novel method to functionalize manganese whitlockite (Mn-WH) with polydopamine (PDA) and hairpin DNA (hpDNA) to improve the water stability and anti-cancer effects of Mn-WH nanoparticles (Mn-WH NPs). Compared to WH NPs, the Mn-WH@PDA-hpDNA NPs exhibit better water dispersibility, high drug loading capacity, excellent photothermal performance, stable MRI imaging ability, and outstanding chemo-photothermal synergistic therapeutic potential against tumors. After intratumoral injection in nude mice, the Mn-WH@PDA-hpDNA-DOX NPs promote complete tumor ablation upon exposure to 808 laser-irradiation. The nanoparticles showed no major side effects or toxicity. Thus, these results indicate that the Mn-WH@PDA-hpDNA-DOX NPs have excellent potential as anti-cancer agents, along with excellent magnetic resonance imaging (MRI) capabilities and the reported functionalization approach provides a novel and effective strategy for the surface functionalization of inorganic nanomaterials.

pH-sensitive O-carboxymethyl chitosan/sodium alginate nanohydrogel for enhanced oral delivery of insulin

Oral drug delivery is considered the most preferred mode of treatment because of its high patient compliance and minimal invasiveness. However, the oral delivery of protein drug has been a difficult problem which restricts its application due to the unstable and inefficient penetration of protein in the gastrointestinal tract. In this study, a novel OCMC/SA nanohydrogel was prepared by using of O-carboxymethyl chitosan (OCMC) and sodium alginate (SA) to solve the problem. The OCMC/SA had a typical nanostructure, which was helpful to increase the specific surface area and enhanced the bioavailability of the drugs. OCMC/SA had a high drug loading capacity and realized passive drug targeting function by responding to the different pH value of the microenvironment. It could have a certain protective effect on drugs in strong acid circumstances, while its structure got loosed and effectively released drugs in intestinal circumstances. OCMC/SA could release the drug for >12 h, and the released insulin could maintain high activity. OCMC/SA nanohydrogel showed promising results in type 1 diabetic rats, and its pharmacological bioavailability was 6.57 %. In conclusion, this study constructed a novel OCMC/SA nanohydrogel, which had a lot of exciting characteristics and provided a new strategy for oral drug delivery.

Adsorptive removal of crystal violet from wastewater using sodium alginate-gelatin-montmorillonite ternary composite microbeads

In this study, the performance of the montmorillonite-filled sodium alginate/gelatin (SA-GEL-MMT) ternary biocomposite microbeads on the adsorptive removal of crystal violet (CV) dye was investigated. Firstly, the composites containing different weight ratios of MMT such as 10 %, 15 %, and 20 % were prepared. The composite beads were cross-linked using a calcium chloride (3%wt/v) solution. To determine the optimum sorption conditions the studies were performed at different parameters namely temperature, pH, contact time, sorbent dose, and dye concentration. From the sorption studies, the maximum capacity of the microbeads was found as 1000.0 mg/g whereas the maximum removal of the dye was 92.1 % at pH = 7 and a temperature of 25 °C. Additionally, the kinetic studies showed that the sorption of the dye followed the pseudo-second-order kinetics. Moreover, the adsorptive removal of the dye occurs spontaneously. This study suggests that the use of SA-GEL-MMT can be highly effective and reusable for the treatment of wastewater.

New chromatographic insights on drug:cyclodextrin inclusion complexes and their potential use in drug delivery

OBJECTIVES

Cyclodextrins (CDs) play a pivotal role in the controlled release of drugs; however, their ability to gradually release drugs is here interrogated: can cyclodextrins, even those that form strong inclusion complexes, sustain a prolonged release of drugs?

METHODS

An original chromatographic approach was developed and accordingly we classified and determined drugs that form the most stable inclusion complexes with cyclodextrins. β-CD and hydroxypropyl-β-CD (HP-β-CD) were coupled to pullulan (Pul) microspheres and packed into a chromatographic column. Then, different drugs or model compounds were eluted, and values of the retention time (RT) were determined. In vitro release studies were performed for drugs that form the most stable inclusion complexes.

RESULTS

The drugs with the longest RT value form the most stable inclusion complexes with Pul/β-CD and Pul/HP-β-CD microspheres. Pul/β-CD microspheres form more stable inclusion complexes than Pul/HP-β-CD microspheres. However, in spite of their high stability, they were not able to gradually release the included drug (15 min release time). The cross-chromatographic experiments confirmed the hypothesis that in aqueous solution, drug/cyclodextrin complexes are continuously associated and dissociated.

CONCLUSIONS

If the dissociation of the guest molecule is very rapid, why is it expected that these complexes gradually release the drug?

Stability of Inhaled Ciprofloxacin-Loaded Poly(2-ethyl-2-oxazoline) Nanoparticle Dry Powder Inhaler Formulation in High Stressed Conditions

In this study, the stability of ciprofloxacin (CIP)-loaded poly(2-ethyl-2-oxazoline) (PEtOx) nanoparticles (NPs) was investigated at normal and high stressed conditions. The blank NPs were used to understand the intrinsic physicochemical properties of the polymer NPs under these storage conditions. The formulated NPs were prepared by a coassembly reaction and dried by lyophilization. The powder NPs were stored at controlled room temperature (25 °C) with normal relative humidity (RH) (43%) and high temperature (40 °C) and RH (75%). The stored samples were analyzed by determining the particle sizes, morphology, solid-state properties, thermal behavior, drug-polymer interactions, and aerosol performances over six months. The chemical stability of the formulations was determined by X-ray diffraction, attenuated total refection-Fourier transform infrared (ATR-FTIR), and high-performance liquid chromatography (HPLC) over six months under both conditions. The particle size of the blank PEtOx NPs significantly (p < 0.05) increased from 195.4 nm to 202.7 nm after 3 months at 40 °C/75% RH due to the moisture absorption from high RH; however, no significant increase was observed afterward. On the other hand, the sizes of CIP-loaded PEtOx NPs significantly (p < 0.05) reduced from 200.2 nm to 126.3 nm after 6 months at 40 °C/75% RH. In addition, the scanning electron microscopy (SEM) images revealed that the surfaces of CIP-loaded PEtOx NPs become smoother after 3 months of storage due to the decay of surface drugs compared to the freshly prepared NPs. However, transmission electron microscopy (TEM) images could not provide much information on drug decay from the nanoparticle’s surfaces. The fine particle fraction (FPF) of CIP-loaded PEtOx NPs dropped significantly (p < 0.05) after three months at 25 °C/43% RH and 40 °C/75% RH conditions. The reduced FPF of CIP-loaded PEtOx NPs occurred due to the drug decay from the polymeric surface and blank PEtOx NPs due to the aggregations of the NPs at high temperatures and RH. Although the aerosolization properties of the prepared CIP-loaded PEtOx NPs were reduced, all formulations were chemically stable in the experimental conditions.

Ionically cross-linked alginate-chitosan core-shell hydrogel beads for oral delivery of insulin

Here, core-shell hydrogel beads for oral insulin delivery at intestine was reported, which was a target site for insulin absorption. The core-shell hydrogel beads were prepared using naturally derived alginate and chitosan polysaccharides by simple dropping technique. In order to effectively control leakage of insulin from core-shell hydrogel beads, insulin was embedded into the layered double hydroxides (LDHs). LDH/insulin-loaded complexes were firstly coated with chitosan, and then coated with alginate to generate core-shell hydrogel beads. The biocompatibility and angiogenic response of core-shell hydrogel beads were evaluated by direct contact of the beads with chick embryo chorioallantoic membrane, which indicates safety of the core-shell beads. The beads successfully retained the insulin within the core-shell structure at pH 1.2, indicating that insulin had a good protective effect in harsh acidic environments. Interestingly, insulin release starts at the simulated intestinal fluid (pH 6.8) and continue to release for 24 h in a sustained manner.

Carboxymethyl starch encapsulated 5-FU and DOX co-loaded layered double hydroxide for evaluation of its in vitro performance as a drug delivery agent

Achieving a new oral drug delivery system with controlled drug release behavior is valuable in cancer therapy. Therefore, for the first time, doxorubicin (DOX) and 5-fluorouracil (5-Fu) were simultaneously co-loaded on the as-synthesized layered double hydroxides LDH(MgAl). The resulted system was encapsulated with carboxymethyl starch to improve its efficiency for colon cancer therapy. Several characterization techniques were used to evaluate the successful synthesis of the CMS@LDH(MgAl)@DOX,5-Fu microspheres. The scanning electron microscopy result showed that the size of prepared microspheres is about 72 μm. Additionally, the presence of one broad peak at 2θ ~ 20 of the X-ray diffraction spectrum approved its amorph nature. The drug release study showed a controlled release profile with ~22% of DOX and 29% of 5-Fu. In addition, the cell viability test outcome confirmed the sustained drug release pattern from CMS@LDH(MgAl)@DOX,5-Fu against the colon cancer cell line. The results suggest that the prepared microspheres are capable to operate as an acceptable formulation for oral co-drug delivery.

Advances and Potentials of Polydopamine Nanosystem in Photothermal-Based Antibacterial Infection Therapies

Bacterial infection remains one of the most dangerous threats to human health due to the increasing cases of bacterial resistance, which is caused by the extensive use of current antibiotics. Photothermal therapy (PTT) is similar to photodynamic therapy (PDT), but PTT can generate heat energy under the excitation of light of specific wavelength, resulting in overheating and damage to target cells or sites. Polydopamine (PDA) has been proved to show plenty of advantages, such as simple preparation, good photothermal conversion effects, high biocompatibility, and easy functionalization and adhesion. Taking these advantages, dopamine is widely used to synthesize the PDA nanosystem with excellent photothermal effects, good biocompatibility, and high drug loading ability, which therefore play more and more important roles for anticancer and antibacterial treatment. PDA nanosystem-mediated PTT has been reported to induce significant tumor inhibition, as well as bacterial killings due to PTT-induced hyperthermia. Moreover, combined with other cancer or bacterial inhibition strategies, PDA nanosystem-mediated PTT can achieve more effective tumor and bacterial inhibitions. In this review, we summarized the progress of preparation methods for the PDA nanosystem, followed by advances of their biological functions and mechanisms for PTT uses, especially in the field of antibacterial treatments. We also provided advances on how to combine PDA nanosystem-mediated PTT with other antibacterial methods for synergistic bacterial killings. Moreover, we further provide some prospects of PDA nanosystem-mediated PTT against intracellular bacteria, which might be helpful to facilitate their future research progress for antibacterial therapy.

Design of a dual pH and temperature responsive hydrogel based on esterified cellulose nanocrystals for potential drug release

In this study, new stimuli - responsive hybrid hydrogels were achieved via succinylated cellulose nanocrystals (Su-CNC). The innovation was concerned with the inclusion of Su-CNC, at different degree of substitution (DS), into hydrogel network to render it pH and thermo-responsive characters through free radical polymerization reaction with poly(N-isopropylacrylamide) (PNIPAm). The prepared hydrogel was also examined for the in vitro release of Famotidine at different pH values. As clearly evident from the results, all the hydrogels prepared with different DS of Su-CNC, which were nominated as Su-CNC / PNIPAm (1-3), showed a high response to temperature change since their swelling behavior and hydrophilicity were decreased at 35 °C and upwards. This led to the more hydrophobicity character and thus the hydrogel shrinkage occurred. On the other hand, at pH 6, the hydrogels exhibited a significant Equilibrium Swelling Ratio (ESR) attaining 18.1, 17.3 and 16.8 (g/g) for Su-CNC / PNIPAm (1-3), respectively. However, Su-CNC / PNIPAm 2 hydrogel showed a significant response to the pH change from 8 to 2 which was advised to be selected as a potential pH responsive hydrogel for the in vitro Famotidine release.

Facile formation of injectable quaternized chitosan/tannic acid hydrogels with antibacterial and ROS scavenging capabilities for diabetic wound healing

The wound healing process of the diabetic wound is often hindered by excessive oxygen free radicals and infection. An ideal wound dressing should possess great reactive oxygen species (ROS) scavenging property and considerable antibacterial ability. In this study, we facilely constructed a novel hydrogel dressing with excellent ROS scavenging property and outstanding antibacterial performance by introducing tannic acid (TA) into quaternized chitosan (QCS) matrix. Attributing to the suitable physical crosslinking between TA and QCS, this QCS/TA hydrogel was endowed with injectable and self-healing properties, which could avoid the various external squeezing on the irregular shape by wound dressing. The results showed that it could promote coagulation, suppress inflammation and expedite collagen deposition in the skin defect model of diabetic rats. This study provides a facile and convenient method for constructing injectable hydrogel dressing, which has application potentials in the clinical management of diabetic wounds.

Selenium-agarose hybrid hydrogel as a recyclable natural substrate for selenium-enriched cultivation of mung bean sprouts

Selenium (Se) is an essential trace element for human beings and animals. Traditional plant Se enrichment technology suffers from selenium pollution. Herein, environmentally friendly Se-agarose (Se-Agar) hybrid hydrogels are prepared by simply mixing agar with different Se species including selenocarrageenan (SeCA), selenite and Se yeast under heating and stirring for 0.5 h without any other reagent. Such Se-Agar hybrid hydrogels with excellent biocompatibility were used as natural substrates for the cultivation of Se-enriched mung bean sprouts. Compared with Se yeast, SeCA and selenite show a better Se enrichment effect on mung bean sprouts. Furthermore, the growth indices including plant weight and plant height of mung bean sprouts were investigated with different concentrations and sources of Se. Notably, the Se-Agar hybrid hydrogels could be easily regenerated and reused for multiple cycles. The results indicated that Se-Agar hybrid hydrogels as recyclable natural substrates offer a simple, sustainable and affordable strategy for plant Se enrichment.

Protein antigen conjugated with cholesteryl amino-pullulan nanogel shows delayed degradation in dendritic cells and augmented immunogenicity

Carriers that augment delivery, immunogenicity or both are crucial in the development of vaccines especially component vaccines as components of pathogens are often poorly immunogenic. Cholesteryl pullulan (CHP) that forms nano-sized hydrogel (nanogel) and encapsulates proteins was shown to be useful in the delivery of vaccines. Here we demonstrate that subcutaneous immunization of mice with bovine serum albumin (BSA) chemically conjugated to NH₂-CHP nanogel induces strong antibody production. This augmented antibody production requires covalent conjugation between BSA and CHP, but does not require nanogel formation. Conjugation of NH₂-CHP nanogel induces persistence of BSA in dendritic cells (DCs) in vivo. As resistance to lysosomal degradation was previously shown to augment antigen presentation by DCs, conjugation of antigens with CHP nanogel may enhance antibody production to antigens by delaying lysosomal degradation. Therefore, delayed degradation of antigens by covalent conjugation with nanoparticles may be a good strategy for the development of effective vaccines.

Nanocomposite base on carboxymethylcellulose hydrogel: Simultaneous absorbent of ethylene and humidity to increase the shelf life of banana fruit

The main purpose of this study was to increase shelf life of banana using active hydrogel. For this purpose, carboxymethylcellulose/nanofiber cellulose/potassium permanganate (CMC/NFC/KMnO₄) hydrogel film was prepared. The morphology and physicochemical properties of CMC hydrogels was investigated. The prepared films were used as humidity/ethylene absorbent in banana packaging for 30 days at 0 and 25 °C. The physical, mechanical and sensory properties of bananas were studied during storage. SEM images confirmed the presence of nanofibers in the hydrogel structure. NFC and KMnO₄ increased the tensile strength of the film and decreased its elongation. On the 15th day of storage, bananas packaged with optimal active hydrogel (CMC/NFC/KMnO₄) at 25 °C had a flavor of 3 and a general acceptance of 3.5, while control bananas had a flavor of 0.5 and a general acceptance of less than 1. On the 30th day of storage, bananas packaged with optimal active hydrogel at 25 °C had a toughness of 4 (N·s) and a firmness of 20 (N), while control bananas had a toughness of about 1 (N·s) and a firmness of about 8 (N). On the 30th day of storage, the humidity inside the package of bananas packed with the optimum active hydrogel at 25 °C was 59.5%, while the humidity in the control packages was 85%, indicating that the hydrogel was able to absorb the moisture inside the package. Totally it can be said that CMC/NFC/KmnO₄ hydrogel can increase shelf life of a banana by simultaneously controlling ethylene and humidity in food packaging.