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.

Sustained release of hydrogen sulfide from anisotropic ferrofluid hydrogel for the repair of spinal cord injury.

Spinal cord injury (SCI) results in massive neuronal death, axonal disruption, and cascading inflammatory response, which causes further damage to impaired neurons. The survived neurons with damaged function fail to form effective neuronal circuits. It is mainly caused by the neuroinflammatory microenvironment at injury sites and regenerated axons without guidance. To address this challenge, a ferrofluid hydrogel (FFH) was prepared with Ferric tetrasulfide (Fe3S4), carboxymethyl chitosan, and gold. Its internal structural particles can be oriented in a magnetic field to acquire anisotropy. Moreover, Fe3S4 can release hydrogen sulfide (H2S) with anti-inflammatory effects under acidic conditions. Regarding in vitro experiments, 0.01g/ml Fe3S4 FFH significantly reduced the inflammatory factors produced by LPS-induced BV2 cells. Oriented and longer axons of the induced neural stem cells loaded on anisotropic FFH were observed. In vivo experiments showed that FFH reduced the activated microglia/macrophage and the expression of pro-inflammatory factors in SCI rats through the NF-κB pathway. Moreover, it significantly promoted directional axonal regrowth and functional recovery after SCI. Given the critical role of inhibition of neuroinflammation and directional axonal growth, anisotropic Fe3S4 FFH is a promising alternative for the treatment of SCI.

Cannabidiol-loaded injectable chitosan-based hydrogels promote spinal cord injury repair by enhancing mitochondrial biogenesis.

The treatment of traumatic spinal cord injury (SCI) remains challenging as the neuron regeneration is impaired by irregular cavity and apoptosis. An injectable in situ gelling hydrogel is therefore developed for the local delivery of cannabidiol (CBD) through a novel method based on polyelectrolyte (PEC) interaction of sodium carboxymethylcellulose (CMC) and chitosan (CS). It can be injected into the spinal cord cavity with a 26-gauge syringe before gelation, and gelled after 110 ± 10 s. Of note, the in-situ forming hydrogel has mechanical properties similar to spinal cord. Moreover, the CBD-loaded hydrogels sustain delivery of CBD for up to 72 h, resulting in reducing apoptosis in SCI by enhancing mitochondrial biogenesis. Importantly, the CBD-loaded hydrogels raise neurogenesis more than pure hydrogels both in vivo and in vitro, further achieving significant recovery of motor and urinary function in SCI rats. Thus, it suggested that CMC/CS/CBD hydrogels could be used as promising biomaterials for tissue engineering and SCI.

COCu: A Robust Self-Regenerative Hydrogel with Applicability as Both Hydrated Gel Dressing and Dry Suture for Seamless Tissue Fixation and Repair.

Self-regenerative hydrogels have recently been developed, and represent a special type of self-healing hydrogels with the ability to restore a dehydrated hydrogel with physical damage. In this study, a self-regenerative hydrogel (COCu) based on two chitosan polymers assembled by slow-released Cu2+ is developed. The COCu hydrogel displays an excellent regeneration ability after being dehydrated and fractured. By simple hydration at room temperature, the fragments of the dehydrated gel fuse into one seamless whole, thereby preserving the mechanical properties and functionalities of the original hydrogel. The regeneration process can be conducted repeatedly after different methods of dehydration (natural volatilization, heat drying, lyophilization) and various modes of deconstruction (flakes, powder, lumpy sponge, etc.). Furthermore, the COCu hydrogel provides ultra-stretchability, and it can be stretched into thin (0.01-0.1 mm) filaments, which, when dried (dtCOCu), can be used as suture lines. Moreover, when used as a dry suture, it regenerates into the hydrogel in the presence of the tissue fluid, forming an excellent sealant to immobilize tissues and seamlessly seal wounds. The fast self-regeneration allows for its facile application as both a hydrated gel dressing and dry suture, and offers customized strategies for fixing and repair of different wounds in soft tissues.

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.

Transparent floatable magnetic alginate sphere used as photocatalysts carrier for improving photocatalytic efficiency and recycling convenience.

Practical application of powder photocatalysts is far from satisfying due to their low photon utilization, inconvenient recovery and potential environmental risk. In this study, an easily recoverable, environmentally friendly and highly transparent floatable magnetic photocatalyst carrier was prepared based on biopolymer alginate and Fe3O4 particles. Further, three different types of photocatalysts were chosen as model semiconductor photocatalysts and loaded on the shell of the carriers. The freeze process facilitated the formation of internal cavities that enhanced floating ability and transparency of the spheres. Meanwhile, the excellent floating performance offered massive reaction sites for pollutants reacting with photocatalysts, O2 and photons on the air/water interface. Photodegradation results showed all three floatable hybrid photocatalysts exhibited enhanced photocatalytic efficiencies compared to the virgin photocatalysts. In short, the carrier can integrate excellent floating ability, environmental friendliness and full recycling with good stability, and it can greatly improve the photocatalytic efficiency of various powder semiconductor photocatalysts.

Long-term antibacterial composite via alginate aerogel sustained release of antibiotics and Cu used for bone tissue bacteria infection.

Bone related-bacterial diseases including wound infections and osteomyelitis (OM) remain a serious problem accompanied with amputation in most severe cases. In this work, we report an exceptional effective antibacterial alginate aerogel, which consists of tigecycline (TGC) and octahedral Cu crystal as an organo-inorganic synergy platform for antibacterial and local infection therapy applications. The alginate aerogel could greatly prolong the release of copper ions and maintain effective antibacterial concentration over 18 days. The result of in-vitro experiments demonstrated that the alginate aerogel has an exceptional effective function on antibacterial activity. Cytotoxicity tests indicated that the alginate aerogel has low biological toxicity (average cell viability >75%). These remarkable results suggested that the alginate aerogel exhibits great potential for the treatment of OM, and has a prosperous future of application in bone tissue engineering.

An advanced sol-gel strategy for enhancing interfacial reactivity of iron oxide nanoparticles on rosin biochar substrate to remove Cr(VI).

The application of iron oxide nanoparticles (IONs) is often limited by agglomeration and low loading. Here, we presented a facile phase change material (PCM) -based sol-gel strategy for the fabrication of α-Fe2O3 nanoparticles. Rosin was used as the PCM in the sol-gel process and the carbon-based substrate of α-Fe2O3 nanoparticles in the thermal process. The α-Fe2O3 nanoparticle embedded rosin-derived biochar(α-Fe2O3@HrBc)were highly dispersed. The dispersity of α-Fe2O3 nanoparticle could be regulated by the weight ratios of rosin to FeCl3·6H2O during the preparation, as evidenced by the scanning electron microscope (SEM) spectrum and the sorption capacity results. Among a series of α-Fe2O3@HrBc nanocomposites, the one with the weight ratios of 1/1.5 rosin/FeCl3·6H2O had the highest capacity for hexavalent chromium (Cr(VI)) sorption. This phenomenon can be ascribed to a remarkably enhanced interfacial reactivity due to an increase in the dispersity of α-Fe2O3 nanoparticle. In addition, SEM showed that the majority of α-Fe2O3 nanoparticles was dispersed on and inside the biochar substrate. Batch adsorption experiments revealed that the α-Fe2O3@HrBc adsorbed 90% Cr(VI) within one minute, and the maximum capacity was up to 166 mg·g-1 based on the Langmuir model. The FTIR and XPS spectra revealed that the adsorbed Cr(VI) species were partially reduced to less toxic Cr(III). Considering that α-Fe2O3 nanoparticles provided important sorption sites, the newly formed Cr(III) and the remaining Cr(VI) ions could be adsorbed on α-Fe2O3@HrBc via the formation of FeCr coprecipitation.

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.

Floatable, macroporous structured alginate sphere supporting iron nanoparticles used for emergent Cr(VI) spill treatment.

Treatment of hexavalent chromium (Cr(VI)) spill accident is a great challenge due to its high toxicity, sudden and extensiveness. In this study, we designed and fabricated a hierarchical, ordered and macroporous structured alginate sphere to support in-situ synthesized zero-valent iron nanoparticle (the alginate-nZVI sphere). Field emission scanning electron microscope (FESEM) and energy-dispersive X-ray spectroscopy (EDS) images showed well dispersion of nZVI on the composite. This alginate-nZVI sphere exhibited good separability in effective removal of Cr(VI). The result from Cr(VI) removal experiment demonstrated a Cr(VI) removal efficiency of 98.2% at equilibrium time, which can be ascribed to the well dispersion of the nZVI. In addition, the alginate-nZVI sphere was effective in Cr(VI) removal in a wide range of pH from 3.0 to 11.0, by the merit of alginate substrate. Hence, the alginate-nZVI sphere might be a promising agent for an emergent Cr(VI) spill treatment by enhancing the dispersion, stabilization and separation properties of nZVI.

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.

Cross-linked succinyl chitosan as an adsorbent for the removal of Methylene Blue from aqueous solution.

Removal of a basic dye (Methylene Blue) from aqueous solution was investigated using a cross-linked succinyl-chitosan (SCCS) as sorbent. The chemical structures of chitosan and its derivatives were testified by FT-IR. X-ray diffraction, DTG analysis and swelling measurements were conducted to clarify the characteristics of the chemically modified chitosan. The effect of process parameters, such as pH of the initial solution, and concentrations of dyes on the extent of Methylene Blue (MB) adsorption was investigated. The Langmuir isotherm model was used to fit the equilibrium experimental data, giving a maximum sorption capacity of 289.02 mg/g at 298 K. Kinetic studies showed that the kinetic data were well described by the pseudo-second-order kinetic model. Thermodynamic parameters such as enthalpy change (ΔH°), free energy change (ΔG°) and entropy change (ΔS°) were determined to be -25.32 kJmol(-1), -6.76 kJmol(-1) and -62.36 Jmol(-1) K(-1), respectively, which leads to a conclusion that the adsorption process is spontaneous and exothermic.

Chemical modification of chitosan by tetraethylenepentamine and adsorption study for anionic dye removal.

To utilize the contribution of introduced amino groups to the adsorption of an anionic dye (eosin Y), a batch adsorption system was applied to study the adsorption of eosin Y from aqueous solution by tetraethylenepentamine (TEPA) modified chitosan (TEPA-CS). Experiments were carried out as a function of particle size, initial pH, agitation rate, adsorbent dosage, agitation period, temperature and initial concentration of eosin Y. The Langmuir and Freundlich models were used to fit the adsorption isotherms. From the values of correlation coefficients (R2), it was observed that the experimental data fit very well to the Langmuir model, giving a maximum sorption capacity of 292.4mg/g at 298K. Kinetic studies showed that the kinetic data were well described by the pseudo-second-order kinetic model. The thermodynamic study revealed negative value of enthalpy change (ΔH°) and free energy change (ΔG°), indicating spontaneous and endothermic nature of the adsorption of eosin Y on to TEPA-CS.

[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.