Multifunctional pH-responsive hydrogel dressings based on carboxymethyl chitosan: Synthesis, characterization fostering the wound healing.

Antibiotic abuse is increasing the present rate of drug-resistant bacterial wound infections, producing a significant healthcare burden globally. Herein, we prepared a pH-responsive CMCS/PVP/TA (CPT) multifunctional hydrogel dressing by embedding the natural plant extract TA as a nonantibiotic and cross-linking agent in carboxymethyl chitosan (CMCS) and polyvinylpyrrolidone (PVP) to prompt wound healing. The CPT hydrogel demonstrated excellent self-healing, self-adaptive, and adhesion properties to match different wound requirements. Importantly, this hydrogel showed pH sensitivity and exhibited good activity against resistant bacteria and antioxidant activity by releasing TA in case of bacterial infection (alkaline). Furthermore, the CPT hydrogel exhibited coagulant ability and could rapidly stop bleeding within 30 s. The biocompatible hydrogel effectively accelerated wound healing in a full-thickness skin defect model by thickening granulation tissue, increasing collagen deposition, vascular proliferation, and M2-type macrophage polarization. In conclusion, this study demonstrates that multifunctional CPT hydrogel offers a candidate material with potential applications for infected skin wound healing.

A suturable biohydrogel with mechanical matched property based on coating chitosan and polyethylene glycol shell for tissue patching.

The mechanical mismatch between soft hydrated tissues and sutures has become a common negative impact on wound healing process. A novel method of coating multilayer polymer shells is thus reported to improve the mechanical performance of hydrogel sutures. It is suitable for tissue patching and shows advantages of convenient, efficient, and biosafety. Specifically, a precursor hydrogel (Cu@CMC) consisted of carboxymethyl chitosan and copper modified by carbon dots was used as the inner sheath, and then bonding the precursor hydrogel sheath with toughening polyethylene glycol network by anchoring sites composited from rigid chitosan shell integrated a whole structure. Subsequently, the whole system was soaked with EtOH, and rapid dehydration of EtOH was used to accelerate the entanglement process between the two coatings by constricting the molecular chains. Finally, an ideal suture (Cu-fiber) with both toughness and rigidness was obtained. The data showed that the tensile strength and biosafety of the hydrogel sutures prepared by the new strategy were significantly improved, and the skin, liver and vessel of rodents can be sutured without secondary damage. Moreover, it can inhibit inflammation response and promote the healing process of skin wound, indicating that the Cu-fiber will become a great candidate for tissue patching.

One-step removal of harmful algal blooms by dual-functional flocculant based on self-branched chitosan integrated with flotation function.

Harmful algal blooms induce severe environmental problems. It is challenging to remove algae by the current available treatments involving complicate process and costly instruments. Here, we developed a CaO2@PEG-loaded water-soluble self-branched chitosan (CP-SBC) system, which can remove algae from water in one-step without additional instrumentation. This approach utilizes a novel flocculant (self-branched chitosan) integrated with flotation function (induced by CaO2@PEG). CP-SBC exhibited better flocculation performance than commercial flocculants, which is attributed to the enhanced bridging and sweeping effect of branched chitosan. CP-SBC demonstrated outstanding biocompatibility, which was verified by zebrafish test and algae activity test. CaO2@PEG-loaded self-branched chitosan can serve as an "Air flotation system" to spontaneous float the flocs after flocculation by sustainably released O2. Furthermore, CP-SBC can improve water quality through minimizing dissolved oxygen depletion and reducing total phosphorus concentrations.

A Nanoparticle-Decorated Biomolecule-Responsive Polymer Enables Robust Signaling Cascade for Biosensing.

To meet the increasing demands for ultrasensitivity in monitoring trace amounts of low-abundance early biomarkers or environmental toxins, the development of a robust sensing system is urgently needed. Here, a novel signal cascade strategy is reported via an ultrasensitive polymeric sensing system (UPSS) composed of gold nanoparticle (gNP)-decorated polymer, which enables gNP aggregation in polymeric network and electrical conductance change upon specific aptamer-based biomolecular recognition. Ultralow concentrations of thrombin (10-18 m) as well as a low molecular weight anatoxin (165 Da, 10-14 m) are detected selectively and reproducibly. The biomolecular recognition induced polymeric network shrinkage responses as well as dose-dependent responses of the UPSS are validated using in situ real-time atomic-force microscopy, representing the first instance of real-time detection of biomolecular binding-induced polymer shrinkage in soft matter. Furthermore, in situ real-time confocal laser scanning microscopy imaging reveals the dynamic process of gNP aggregation responses upon biomolecular binding.

A Hydrogel-Based Hybrid Theranostic Contact Lens for Fungal Keratitis.

Fungal keratitis, a severe ocular disease, is one of the leading causes of ocular morbidity and blindness, yet it is often neglected, especially in developing countries. Therapeutic efficacy of traditional treatment such as eye drops is very limited due to poor bioavailability, whereas intraocular injection might cause serious side effects. Herein, we designed and fabricated a hybrid hydrogel-based contact lens which comprises quaternized chitosan (HTCC), silver nanoparticles, and graphene oxide (GO) with a combination of antibacterial and antifungal functions. The hydrogel is cross-linked through electrostatic interactions between GO and HTCC, resulting in strong mechanical properties. Voriconazole (Vor), an antifungal drug, can be loaded onto GO which retains the drug and promotes its sustained release from the hydrogel-based contact lenses. The contact lenses also exhibited good antimicrobial functions in view of glycidyltrimethylammonium chloride and silver nanoparticles. The results from in vitro and in vivo experiments demonstrate that contact lenses loaded with Vor have excellent efficacy in antifungal activity in vitro and could significantly enhance the therapeutic effects on a fungus-infected mouse model. The results indicate that this hydrogel contact lenses-based drug delivery system might be a promising therapeutic approach for a rapid and effective treatment of fungal keratitis.

Starch derivative-based superabsorbent with integration of water-retaining and controlled-release fertilizers.

Phosphate rock (PHR), a traditional fertilizer, is abundant, but is hard to be utilized by plants. To improve the utilization of PHR, and to integrate water-retaining and controlled-release fertilizers, an agricultural superabsorbent polymer based on sulfonated corn starch/poly (acrylic acid) embedding phosphate rock (SCS/PAA/PHR) was prepared. PHR can be suspended and well-dispersed in SCS/PAA by sulfonated corn starch (SCS). PHR and KOH were mixed in acrylic acid solution to provide phosphorus (P) and potassium (K) nutrients, respectively. Impacts on water absorption capacity of the superabsorbent were investigated. The maximum swelling capacity in distilled water or 0.9 wt.% (weight percent) NaCl solution reached 498 g g(-1) and 65 g g(-1) (water/prepared dry superabsorbent) respectively. Moreover, release behaviours of P and K in SCS/PAA/PHR were also investigated. The results showed that SCS/PAA/PHR possessed excellent sustained-release property of plant nutrient, and the SCS/PAA could improve the P release greatly. Besides, the XPS analysis was employed to study the relationship between PHR and superabsorbent polymer.

Sugarcane bagasse derivative-based superabsorbent containing phosphate rock with water-fertilizer integration.

To improve the water-fertilizer utilization ratio and mitigate the environmental contamination, an eco-friendly superabsorbent polymer (SPA), modified sugarcane bagasse/poly (acrylic acid) embedding phosphate rock (MSB/PAA/PHR), was prepared. Ammonia, phosphate rock (PHR) and KOH were admixed in the presence of acrylic acid to provide nitrogen (N), phosphorus (P) and potassium (K) nutrients, respectively. Impacts on water absorption capacity of the superabsorbent polymer (SAP) were investigated. The maximum swelling capacity in distilled water and 0.9 wt.% (weight percent) NaCl solution reached 414 gg(-1) and 55 gg(-1) (water/prepared SAP), respectively. The available NPK contents of the combination system were 15.13 mgg(-1), 6.93 mgg(-1) and 52.05 mgg(-1), respectively. Moreover, the release behaviors of NPK in the MSB/PAA/PHR were also studied. The results showed that the MSB/PAA/PHR has outstanding sustained-release plant nutrients property.

Potential biosorbent based on sugarcane bagasse modified with tetraethylenepentamine for removal of eosin Y.

Tetraethylenepentamine (TEPA) modified sugarcane bagasse (SB), a novel biosorbent (TEPA-MSB), was proved to be an effective adsorbent for anionic dyes due to the introduced functional amino groups. FTIR, TG and DSC analysis were employed to characterize the sorbent. The effects of pH, temperature, contact time and initial concentration of dye on the adsorption of eosin Y were investigated. The experimental data fit very well to the Langmuir model, giving a maximum sorption capacity of 399.04 mg/g at 25 °C. And the kinetic data were well described by the pseudo-second-order kinetic model. pH 6 was the optimal pH for eosin Y adsorption, and the maximum adsorption capacity of TEPA-MSB calculated by Langmuir model was 18 times higher than that of SB.

[In vitro drug release from a mitomycin C delivery system and its effect against scar tissue adhesion in vivo].

OBJECTIVE: To develop a chitosan (CH)/polyethylene glycols succinate acid (PEG-SA)-mediated mitomycin C (MMC) delivery system and investigate its drug release characteristics in vitro and its effect against scar tissue adhesion in vivo. METHODS: Mitomycin C loading in the composite CH/PEG-SA/MMC films was determined using ultraviolet. The freeze-dried films were dispersed in 1 ml PBS (pH7.4) and mitomycin C release in vitro was determined according to the mitomycin C concentration-UV value standard curve. The influence of the film structure on the drug release was evaluated. The drug delivery system was then implanted in SD rats, and 4 weeks later, immunohistochemical and histological examinations were carried out to assess the therapeutic effect on epidural scar tissue. RESULTS: The linear regression equation of the mitomycin C concentration-UV value standard curve was y=0.593x(3)-2.563x(2)+25.944x-0.236 (R(2)=1.000). The film demonstrated good drug delivery capability, and 20 mg of the samples in PBS showed a peak mitomycin C release after 12 days of 14.9616 microg/ml, which was higher than the ID(50) of mitomycin C (10.4713 microg/l) to the fibroblasts. On days 18 and 32, another two drug release peaks occurred (14.4824 microg/ml and 11.4092 microg/ml, respectively), followed by maintenance of slow release. Till day 60, the accumulative mitomycin release reached 0.1793 microg/ml, and the loaded drug was ultimately completely released. Significant differences were noted in the hydroxyproline content in the scar tissues of different groups (F=12.085, P=0.000), and the CH/PEG-SA/MMC DDS reduced the amount of scar tissue and promoted its orderly alignment to control potential scar hyperplasia that may compress the spinal cord and nerve roots. CONCLUSION: The composite film for drug delivery possesses good flexibility and mechanical properties and allows sustained drug release of mitomycin C to prevent epidural scar tissue adhesion following lumbar laminectomy.

Novel polymer micelles prepared from chitosan grafted hydrophobic palmitoyl groups for drug delivery.

Chitosan-based polymer micelles have a splendid outlook for drug delivery owing to the interesting properties, abundance, and low cost of chitosan. A new method of preparation of water-soluble N-palmitoyl chitosan (PLCS) which can form micelles in water is developed in this paper. The preparation of PLCS was carried out by swollen chitosan coupling with palmitic anhydride in dimethyl sulfoxide (DMSO). The degree of substitution (DS) of PLCS was in the range of 1.2-14.2%, and the critical aggregation concentration (CAC) of PLCS micelles was in the range of 2.0 x 10(-3) to 37.2 x 10(-3) mg/mL. The properties of PLCS micelles such as encapsulation capacity and controlled release ability of hydrophobic model drug ibuprofen (IBU) were evaluated. Experimental results indicated that the loading capacity (LC) of PLCS was approximately 10%. The drug release strongly depended on pH and temperature: low pH and high temperature accelerated drug release markedly. Moreover, the IR, 1H NMR, and TEM of PLCS, IBU-loaded PLCS, and a PLCS-IBU physical mixture have been measured to show that IBU is loaded by PLCS micelles.