Injectable antibacterial conductive nanocomposite cryogels with rapid shape recovery for noncompressible hemorrhage and wound healing

One-pot preparation of double network hydrogels via enzyme-mediated polymerization and post-self-assembly for wound healing

An enzymatic one-pot preparation method is used to prepare double network hydrogels for wound healing.

Injectable drug-loaded polysaccharide hybrid hydrogels for hemostasis

An injectable hydrogel with high adhesion strength, non-toxicity and low cost is highly desired for developing highly efficient hemostasis. In this study, we developed a new type of injectable adhesive drug loaded hydrogel utilizing the formation of Schiff-base linkages based on carboxymethyl chitosan (CMC), gelatin (GEL) and oxidized alginate (OSA). By optimizing the concentration of the biopolymers, the hybrid hydrogel (CMC-GEL/OSA) demonstrated an extremely fast gelation rate (30 s) and adhesive strength of 11 kPa. The freeze-dried hydrogel showed a three-dimensional porous structure. The hydrogel loaded with levofloxacin exhibited good antibacterial properties. Hemostatic performance of the hydrogel was demonstrated in a rat liver injury model. Compared with the untreated wound, the hemostasis time of the hydrogel treated wound was shortened by 84.2% and the blood loss was reduced by 82.2%. Thus, the proposed injectable hydrogel holds great potential applications for hemostasis, drug delivery and in other biomedical fields.

A levofloxacin loaded CMC-GEL/OSA hydrogel was synthesized that exhibited good antibacterial properties, 84.2% shortened hemostatic time and 82.2% reduced blood loss.

Surgery-free injectable macroscale biomaterials for local cancer immunotherapy

Up-to-date review and perspective on injectable macroscale biomaterials for local cancer immunotherapy.

Synthetic poly(vinyl alcohol)–chitosan as a new type of highly efficient hemostatic sponge with blood-triggered swelling and high biocompatibility

Synthetic poly(vinyl alcohol)–chitosan as a new type of highly efficient hemostatic sponge with blood-triggered swelling and high biocompatibility.

Effects and formulation of silver nanoscaffolds on cytotoxicity dependent ion release kinetics towards enhanced excision wound healing patterns in Wistar albino rats

Wound tissue regeneration and angiogenesis are dynamic processes that send physiological signals to the body. Thus, designing novel nanoscaffolds by understanding their surface modifications and toxicological response in a biological system with a potent anti-inflammatory response is a viable solution. In this respect, inspired by the surface chemistry, in the present work we focus on the chemical optimization of silver nanoscaffolds using surface cappings in order to understand their kinetic release behaviour in simulated wound fluids (SWF), to analyze their blood compatibility in human lymphocytes and erythrocytes and then embed them in a chitosan-agarose matrix (CAM) as a productive drug delivery system to evaluate in vivo excision wound tissue regeneration efficiency in Wistar rats. In this regard, polyvinyl alcohol capped silver nanocomposites (PVA-AgNPs) exhibit a dominant antibacterial efficacy with the sustained and controlled release of silver ions and percentage cell mortality and percentage hemolysis of only 10% and 16% compared with uncapped-AgNPs or silver bandaids (SBDs). Also, PVA-AgNP impregnated CAM (PVA-CAM) shows positive effects through their anti-inflammatory and angiogenic properties, with a nearly 95% healing effect within 9 days. The complete development of collagen and fibroblast constituents was also monitored in PVA-CAM by hematoxylin & eosin (H & E) and Masson trichrome (MT) staining. These results provide a clear insight into the development of a potent therapeutic formulation using CAM as a scaffold incorporated with surface functionalized PVA-AgNPs as a bioeffective and biocompatible polymer for the fabrication of efficacious silver wound dressing scaffolds in clinical practice.

A sustained and controlled release of silver ions from AgNPs is driven by greater percentage of wound contraction with minimal cytotoxic behavioural rates and effective antibacterial activity.

A body temperature and water-induced shape memory hydrogel with excellent mechanical properties

A body temperature and water-induced shape memory hydrogel with excellent mechanical properties was prepared by crosslinking dopamine-terminated tetra-poly(ethylene glycol) with an oxidation reaction.

Shape-changing polymers for biomedical applications

Smart polymers that are capable of controlled shape transformations under external stimuli have attracted significant attention in the recent years due to the resemblance of this behavior to the biological intelligence observed in nature. In this review, we focus on the recent progress in the field of shape-morphing polymers, highlighting their most promising applications in the biomedical field.

A simple strategy to enhance the in vivo wound-healing activity of curcumin in the form of self-assembled nanoparticle complex of curcumin and oligochitosan

While the wound healing activity of curcumin (CUR) has been well-established, its clinical effectiveness remains limited due to the inherently low aqueous CUR solubility, resulting in suboptimal CUR exposure in the wound sites. Previously, we developed high-payload amorphous nanoparticle complex (or nanoplex) of CUR and chitosan (CHI) capable of CUR solubility enhancement by drug-polyelectrolyte complexation. The CUR-CHI nanoplex, however, exhibited poor colloidal stability due to its strong agglomeration tendency. Herein we hypothesized that the colloidal stability could be improved by replacing CHI with its oligomers (OCHI) owed to the better charge distribution in OCHI. The effects of key parameters in drug-polyelectrolyte complexation (i.e. pH, salt inclusion, CUR concentration, and OCHI/CUR charge ratio) on the physical characteristics and preparation efficiency of the CUR-OCHI nanoplex produced were investigated. The in vivo wound healing efficacy of the CUR-OCHI nanoplex and its cytotoxicity towards human keratinocytes cells were examined. The results showed that CUR-OCHI nanoplex exhibited prolonged colloidal stability (72 h versus <24 h for the CUR-CHI nanoplex). At the optimal condition, the CUR-OCHI nanoplex (without ultrasonication) exhibited size, zeta potential, and CUR payload of ≈140 nm, 20 mV, and 78% (w/w), respectively. The nanoplex preparation was simple yet robust at nearly 100% CUR utilization rate. The CUR-OCHI nanoplex exhibited superior wound healing efficacy to the native CUR with wound closure of >90% after 7 days versus 9 days for the native CUR resulting in smaller scars, attributed to its generation of high CUR concentration in the wound sites.

Investigation of the Effects of Molecular Parameters on the Hemostatic Properties of Chitosan

Hemorrhea is one of the major problems in war, trauma care, and surgical operation that threaten the life of the injured and patients. As a novel polymeric hemostatic agent, biodegradable chitosan can stop bleeding through a variety of approaches. In this paper, chitosan with various molecular parameters was prepared from chitin as raw material through deacetylation, oxidative degradation, hydrophilic modification, and salt formation reactions. The influence of different polymer parameters on the hemostatic effects of chitosan was investigated by in vitro coagulation time and dynamic coagulation assay. The results showed that when the molecular weights were high (10⁵⁻10⁶) and approximate, the coagulation effect of chitosan improved with a decrease of the deacetylation degree and achieved a prominent level in a moderate degree of deacetylation (68.36%). With the same degree of deacetylation, the higher the molecular weight of chitosan, the better the procoagulant effect. The substituent derivatives and acid salts of chitosan showed significant procoagulant effects, especially the acid salts of chitosan. In addition, the hemostasis mechanism of chitosan with various parameters was preliminarily explored by analyzing the plasma recalcification time (PRT). The efforts in this paper laid a basis for further study of the structure⁻activity relationship and the mechanism of chitosan hemostasis.

Preparation and Characterization of Chitosan/β-Glycerophosphate Thermal-Sensitive Hydrogel Reinforced by Graphene Oxide

Thermal-sensitive hydrogel based on chitosan (CS) and β-glycerophosphate (GP) has shown good biocompatibility and biodegradability. But the application of such hydrogel is limited due to its poor mechanical property. Recently, graphene oxide(GO) is widely used as a reinforcement agent to prepare nanocomposites with different polymers for improving the properties of the materials. In this study, CS/GP-based hydrogels with different weight ratio of GO/CS (0.5, 1, 2%) were fabricated. The gelation time of the hydrogels at body temperature was evaluated by tube inverting method. The gelation process during heating was monitored by rheological measurement. The morphology, porosities, chemical structure, swelling properties of the lyophilized hydrogels were investigated by scanning electron microscopy, liquid displacement method, Fourier transform infrared spectroscopy and gravimetric method. Mechanical property of the hydrogels was analyzed by rheological measurement and unconfined compression test. MC3T3-E1 mouse pre-osteoblast cell line was used to assess the biological properties of the hydrogels. The results obtained from those assessments revealed that the addition of GO into CS/GP improved the properties of the prepared hydrogels without changing the high porous and interconnected microstructure and swelling ability of the hydrogels. The gelation time at body temperature was significantly reduced by nearly 20% with the addition of small amount of GO (0.5% weight ratio of CS). The mechanical properties of the hydrogels containing GO were improved significantly over that of CS/GP. The storage (G′)/loss (G″) moduli of the hydrogels with GO were 1.12 to 1.69 times that of CS/GP at the gelling temperature. The Young's modulus of 0.5%GO/CS/GP hydrogel is 1.76 times that of CS/GP. Moreover, the 0.5%GO/CS/GP hydrogel revealed remarkable biological affinity such as cellular attachment, viability and proliferation. All of these results suggest that 0.5%GO/CS/GP hydrogel has great potential for practical application in biomedical field.

Conductive and Tough Hydrogels Based on Biopolymer Molecular Templates for Controlling in Situ Formation of Polypyrrole Nanorods

Conductive hydrogels (CHs) have gained significant attention for their wide applications in biomedical engineering owing to their structural similarity to soft tissues. However, designing CHs that combine biocompatibility with good mechanical and electrical properties is still challenging. Herein, we report a new strategy for the fabrication of tough CHs with excellent conductivity, superior mechanical properties, and good biocompatibility by using chitosan framework as molecular templates for controlling conducting polypyrrole (PPy) nanorods in situ formation inside the hydrogel networks. First, polyacrylamide/chitosan (CS) interpenetrating polymer network hydrogel was synthesized by UV photopolymerization; second, hydrophobic and conductive pyrrole monomers were absorbed and fixed on CS molecular templates and then polymerized with FeCl₃ in situ inner hydrophilic hydrogel network. This strategy ensured that the hydrophobic PPy nanorods were uniformly distributed and integrated with the hydrophilic polymer phase to form highly interconnected conductive path in the hydrogel, endowing the hydrogel with high conductivity (0.3 S/m). The CHs exhibited remarkable mechanical properties after the chelation of CS by Fe³⁺ and the formation of composites with the PPy nanorods (fracture energy 12 000 J m^-2 and compression modulus 136.3 MPa). The use of a biopolymer molecular template to induce the formation of PPy nanostructures is an efficient strategy to achieve conductive multifunctional hydrogels.

pH-responsive injectable hydrogels with mucosal adhesiveness based on chitosan-grafted-dihydrocaffeic acid and oxidized pullulan for localized drug delivery

Injectable hydrogels with multifunctional properties, including tissue adhesiveness and pH-sensitivity are highly desired for localized drug delivery in disease treatment, and their design is still challenging. We developed a series of multifunctional injectable mucoadhesive and pH-responsive hydrogels based on chitosan-grafted-dihydrocaffeic acid (CS-DA) and oxidized pullulan (OP) via a Schiff base reaction. These hydrogels exhibited good injectability, suitable gelation time, in vitro pH-dependent equilibrated swelling ratios, morphologies, and rheological characteristics. The desirable in vitro pH-sensitive drug release behavior of these hydrogels was demonstrated by a drug release test with anti-cancer drug doxorubicin (DOX) loaded hydrogels at different pH values. The hydrogels showed good DOX release, effectively killing colon tumor cells (HCT116 cells) and good antibacterial properties against E. coli and S. aureus in vitro when the antibacterial model drug amoxicillin was encapsulated in the hydrogels. A lap-shear test was also carried out with these hydrogels. The hydrogels exhibited good mucosal adhesion, indicating their potential use in mucosa-localized drug delivery systems. All these results suggest that these injectable pH-responsive adhesive hydrogels are ideal candidates for development of colon cancer drug delivery carriers or mucoadhesive drug delivery systems.

Hemostasis and anti-necrotic activity of wound-healing dressing containing chitosan nanoparticles

Necrotic tissues are the dead tissues present in the wounded areas, which need to be removed for rapid wound healing. Various biopolymer-based dressings have been exploited to heal infected wounds, but with limited success. In a quest to develop an effective and economic wound dressing, a biodegradable dressing containing chitosan nanoparticles has been successfully developed. Chitosan nanoparticles were prepared by ionic gelation method and then assembled into the porous chitosan dressing, by lyophilization. The resulting dressing was analyzed for morphology, porosity, pore volume, surface area and biodegradability. Higher surface area and porosity of the dressing facilitated its partial biodegradation by enzymatic action. In vitro cellular investigations with Human Dermal Fibroblasts (HDF) confirmed the safety of the dressing for wound healing applications. Human Thrombin-Antithrombin (TAT) based in vitro ELISA assay, for evaluating the hemostasis activity, illustrated an accelerated hemostasis activity, through higher thrombin generation and stable blood clot formation. The blood in contact with the dressing contained two-fold higher levels of TAT, as compared to that in contact with the TAT standard. Our results suggest the potential of the developed dressing for removing the necrotic tissues and accelerating the hemostasis activity, for efficient and rapid wound healing.

Facile Fabrication of Sandwich Structural Membrane With a Hydrogel Nanofibrous Mat as Inner Layer for Wound Dressing Application

A common problem existing in wound dressing is to integrate the properties of against water erosion while maintaining a high water-uptake capacity. To tackle this issue, we imbedded one layer of hydrogel nanofibrous mat into two hydrophobic nanofibrous mats, thereafter, the sandwich structural membrane (SSM) was obtained. Particularly, SSM is composed of three individual nanofibrous layers which were fabricated through sequential electrospinning technology, including two polyurethane/antibacterial agent layers, and one middle gelatin/rutin layer. The obtained SSM is characterized in terms of morphology, component, mechanical, and functional performance. In addition to the satisfactory antibacterial activity against Staphylococcus aureus and Escherichia coli, and antioxidant property upon scavenging DPPH free radicals, the obtained SSM also shows a desirable thermally regulated water vapor transmission rate. More importantly, such SSM can be mechanically stable and keep its intact morphology without appearance damage while showing a high water-absorption ratio. Therefore, the prepared sandwich structural membrane with hydrogel nanofibrous mat as inner layer can be expected as a novel wound dressing.