Hydrogel Based on Riclin Cross-Linked with Polyethylene Glycol Diglycidyl Ether as a Soft Filler for Tissue Engineering.

Hydrogels composed of natural polysaccharides have been widely used as filling materials, with a growing interest in medical cosmetology and skin care. However, conventional commercial dermal fillers still have limitations, particularly in terms of mechanical performance and durability in vivo. In this study, a novel injectable and implantable hydrogel with adjustable characteristics was prepared from succinoglycan riclin by introducing PEG diglycidyl ether as a cross-linker. FTIR spectra confirmed the cross-linking reaction. The riclin hydrogels exhibited shear-thinning behavior, excellent mechanical properties, and cytocompatibility through in vitro experiments. Furthermore, when compared with subcutaneous injection of a commercial hyaluronic acid hydrogel, the riclin hydrogels showed enhanced persistence and biocompatibility in Balb/c mice after 16 weeks. These results demonstrate the great potential of the riclin-based hydrogel as an alternative to conventional commercial soft tissue fillers.

Salecan-Based pH-Sensitive Hydrogels for Insulin Delivery.

Stimuli-responsive polymeric hydrogels are promising and appealing delivery vehicles for protein/peptide drugs and have made protein/peptide delivery with both dosage- and spatiotemporal-controlled manners possible. Here a series of new Salecan-based pH-sensitive hydrogels were fabricated for controlled insulin delivery via the graft copolymerization reaction between Salecan and 2-acrylamido-2-methyl-1-propanesulfonic acid. In this study, on one hand, Salecan played a key role in modifying the structure and the pore size of the developing hydrogel. On the other hand, Salecan tuned the water content and the water release rate of the obtained hydrogel, leading to a controllable release rate of the insulin. More importantly, in vitro release experiments validated that the release of insulin from this intelligent system could be also tailored by the environmental pH of the release medium. For SGA2, the amount of encapsulated insulin released at gastric conditions (pH 1.2) was relatively low (about 26.1 wt % in 24 h), while that released at intestinal conditions (pH 7.4) increased significantly (over 50 wt % in 6 h). Furthermore, toxicity assays demonstrated that the designed hydrogel carriers were biocompatible. These characteristics make the Salecan-based hydrogel a promising candidate for protein/peptide drug delivery device.

Exopolysaccharide riclin and anthocyanin-based composite colorimetric indicator film for food freshness monitoring.

Food freshness monitoring is vital to ensure food safety. Recently, packaging materials incorporating pH-sensitive films have been employed to monitor the freshness of food products in real time. The film-forming matrix of the pH-sensitive film is essential to maintain the desired physicochemical functions of the packaging. Conventional film-forming matrices, such as polyvinyl alcohol (PVA), have drawbacks of low water resistance, poor mechanical properties, and weak antioxidant ability. In this study, we successfully synthesise PVA/riclin (P/R) biodegradable polymer films to overcome these limitations. The films feature riclin, an agrobacterium-derived exopolysaccharide. The uniformly dispersed riclin conferred outstanding antioxidant activity to the PVA film and significantly improved its tensile strength and barrier properties by forming hydrogen bonds. Purple sweet potato anthocyanin (PSPA) was used as a pH indicator. The intelligent film with added PSPA provided robust surveillance of volatile ammonia and changed its color within 30 s in the pH range of 2-12. This multifunctional colorimetric film also engendered discernible color changes when the quality of shrimp deteriorated, demonstrating its great potential as an intelligent packaging material to monitor food freshness.

Characterizing the obesogenic and fatty liver-inducing effects of Acetyl tributyl citrate (ATBC) plasticizer using both in vivo and in vitro models.

The global incidence of obesity and non-alcoholic fatty liver disease (NAFLD) is rising rapidly in recent years. Environmental factors including usage of plastics and exposure to chemicals have been proposed as important contributors to the obesity pandemic. Acetyl tributyl citrate (ATBC) is a non-phthalate plasticizer widely used in food packaging, personal care products, medical devices and children's toys etc. Due to its high leakage rate from plastics, exposure risk of ATBC keeps increasing. Although there are some studies investigating the safety of ATBC on human health, these studies mainly focused on high dosages and information regarding ATBC safety at environmental-relevant low levels is still limited. In this study, we aimed to evaluate the safety of subchronic exposure to environmentally-relevant concentrations of ATBC. C57BL/6J mice were orally exposed to ATBC for 6 or 14 weeks. Results indicated that ATBC exposure increased the body weight gain, the body fat content and the size of adipocytes, induced liver steatosis in mice. Consistent with in vivo effects, ATBC treatment increased the intracellular lipid accumulation in vitro hepatocytes. Transcriptome sequencing, qRT-PCR analysis and western blotting revealed that ATBC exposure affected the expression of genes involved in de novo lipogenesis and lipid uptake. Therefore, based on our subchronic and in vitro results, it suggested that ATBC might be a potential environmental obesogen with metabolism-disturbing and fatty liver-inducing risk, and its application in many consumer products should be carefully re-evaluated.

Riclin-Capped Silver Nanoparticles as an Antibacterial and Anti-Inflammatory Wound Dressing.

Purpose: In order to overcome the inflammatory response to bacterial infection during wound healing, we have fabricated an antibacterial and anti-inflammatory wound dressing based on polysaccharide riclin and silver nanoparticles (AgNPs). Methods: The riclin-AgNPs nanocomposite was developed by borohydride method and was characterized by UV-Vis, TEM, XRD, Zeta potential, DLS. In vitro, we assessed the cumulative release, antibacterial activities and cytotoxicity. In vivo, we examined the wound healing in mice wound infection experiment and inflammatory mediators using histological observations and gene expression analysis. Results: The riclin/AgNPs nanocomposite hydrogel exhibited nanosized orbicular particles with high purity and stability. In vitro, the riclin/AgNPs showed sustained release of AgNPs, effective suppression in pathogen growth and negligible toxicity toward mammalian fibroblasts and macrophage cells. In vivo, the riclin/AgNPs treatment leads to faster and smoother growth of fresh skin with suppressed expression of inflammatory mediators. Conclusion: The reported Riclin-AgNPs nanocomposite hydrogel showed both antibacterial and anti-inflammatory functions, which induce significantly accelerated wound healing, indicating great potential as a novel attractive wound dressing material.

Development of photocrosslinked salecan composite hydrogel embedding titanium carbide nanoparticles as cell scaffold.

Salecan is a water-soluble extracellular ß­glucan and appropriate for preparing hydrogels applicable in biomedical field. Herein, an innovative photocrosslinked composite hydrogel composed of salecan/poly(hydroxypropyl methacrylate (PHPMA) network and titanium carbide (TiC) nanoparticles was successfully prepared. XRD patterns clearly showed the crystal planes of Ti. More importantly, the introduction of TiC nanoparticles into the hydrogel network provided structural reinforcement, and thereby synergistically enhanced the mechanical strength and thermal stability of the hydrogels. The change of salecan content markedly affected the swelling behavior and morphology of the composite hydrogels. Cytotoxicity results revealed that the composite hydrogels were non-toxic to L929 and 3T3L1 cells. Cell proliferation and Live/Dead assay further demonstrated excellent cytocompatibility of the cells within the composite hydrogels, which highlights the value of this system for potential application as soft tissue engineering scaffold.

Magnetic field-driven drug release from modified iron oxide-integrated polysaccharide hydrogel.

Salecan is a novel water-soluble extracellular ß-glucan and suitable for the hydrogel preparation due to its excellent physicochemical and biological properties. The present article describes the fabrication and characterization of a pH/magnetic field-driven hydrogel based on salecan-g-poly(vinylacetic acid-co-2-hydroxyethyl acrylate) [poly(VA-co-HEA)] copolymer and Fe3O4@Agarose nanoparticles for drug release testing. Vibrating sample magnetometer characterization verified that integration of Fe3O4@Agarose nanoparticles in the copolymer provided the sensitivity to magnetic fields. The doxorubicin hydrochloride (DOX) release test showed a pH/magnetic field-triggered and sustained release property, and the release could be accelerated under mildly acidic conditions or the presence of an external magnetic field. Meanwhile, the increase in salecan content could also enhance the release rate. Cytotoxicity assays revealed that the released DOX maintained relatively high killing efficacy of A549 cells. In sum, these salecan-g-poly(VA-co-HEA)/Fe3O4@Agarose hydrogels were well-suited for magnetically targeted drug delivery systems.

Design of a pH-sensitive magnetic composite hydrogel based on salecan graft copolymer and Fe3O4@SiO2 nanoparticles as drug carrier.

Salecan, a novel water-soluble extracellular ß-glucan, is very suitable for the hydrogel preparation. Here, pH-sensitive magnetic composite hydrogel was fabricated by the graft copolymerization of crotonic acid (CA) and N-(hydroxymethyl) acrylamide (HMAA) onto salecan in the presence of Fe3O4@SiO2 nanoparticles for doxorubicin (DOX) delivery. The embedment of Fe3O4@SiO2 nanoparticles into salecan-g-poly(CA-co-HMAA) hydrogel network endowed the material with magnetic property. In addition, DOX not only achieved effectively bound to the composite hydrogel, but also released in a controlled and pH-dependent manner. The application of an external magnetic field could significantly enhance the drug release rate. More importantly, the released DOX preserved its bioavailability. Taken together, these hydrogel drug carriers provide a promising platform for magnetically targeted drug delivery.

Dual-pH/Magnetic-Field-Controlled Drug Delivery Systems Based on Fe3 O4 @SiO2 -Incorporated Salecan Graft Copolymer Composite Hydrogels.

Salecan is a water-soluble extracellular ß-glucan and has excellent physicochemical and biological properties for hydrogel preparation. In this study, a new pH/magnetic field dual-responsive hydrogel was prepared by the graft copolymerization of salecan with 4-pentenoic acid (PA) and N-hydroxyethylacrylamide (HEAA) in the presence of Fe3 O4 @SiO2 nanoparticles for doxorubicin hydrochloride (DOX) release. Integration of Fe3 O4 @SiO2 nanoparticles in salecan-g-poly(PA-co-HEAA) copolymers afforded magnetic sensitivity to the original material. DOX-loaded hydrogels exhibited a clear capacity for pH/magnetic field dual-responsive controlled drug release. Lowering the pH to acidic conditions or introducing an external magnetic field caused an enhancement in DOX release. This salecan-g-poly(PA-co-HEAA)/Fe3 O4 @SiO2 composite hydrogel is a promising drug carrier for magnetically targeted drug delivery with enhanced DOX cytotoxicity against A549 cells.

Synthesis and characterization of a multi-sensitive polysaccharide hydrogel for drug delivery.

Salecan is a novel water soluble polysaccharide produced by a salt-tolerant strain Agrobacterium sp. ZX09. Poly(dimethylaminoethyl methacrylate) (PDMAEMA) is a pH, thermo, and ionic strength multi-sensitive polymer with anti-bacterial property. Here, we report a semi-interpenetrating polymer network (semi-IPN) hydrogel based on salecan and PDMAEMA. The obtained hydrogel is simultaneous sensitive to pH, ionic strength and temperature: the swelling ratio maximizes at pH 1.2 and shrinks at pH value greater than 3; besides, water content of the hydrogel decreases as the ionic strength increases; in terms of temperature, the hydrogel swells/deswells at temperatures below/above 40°C. Cytotoxicity test shows the hydrogel is non-cytotoxic to COS-7 cells. Protein drug insulin was selected as model drug to test the in vitro release behavior of the hydrogel. Results show the release rate increases with the swelling ratio of the hydrogel. In addition, when the temperature is higher than the lower critical solution temperature (LCST) of PDMAEMA, the hydrogel shrinks to extrude more drug molecules. Moreover, the release rate and release amount were higher in acid condition (pH 1.2) than at pH 7.4. In summary, this polysaccharide hydrogel is a promising material for drug delivery.

Preparation of a Salecan/poly(2-acrylamido-2-methylpropanosulfonic acid-co-[2-(methacryloxy)ethyl]trimethylammonium chloride) Semi-IPN Hydrogel for Drug Delivery.

Salecan is a water-soluble bacterial polysaccharide consisting of glucopyranosyl units linked by α-1,3 and ß-1,3 glycosidic bonds. salecan is suitable for the development of hydrogels for biomedical applications, given its outstanding physicochemical and biological profiles. In this study we designed a new semi-interpenetrating polymer network hydrogel that introduces the salecan polysaccharide into a stimuli-responsive poly(2-acrylamido-2-methylpropanosulfonic acid-co-[2-(methacryloxy)ethyl]trimethylammonium chloride) (PAM) hydrogel matrix for controlled insulin release. We found that salecan not only tunes the structure and pore size of the PAM hydrogels, but also endows them with adjustable water release rates. More importantly, in vitro drug loading/release assays demonstrated that insulin is efficiently loaded into the resulting hydrogels and can be released in an on-demand manner by controlling the pH and salecan dose. Furthermore, cell viability and cell adhesion experiments verified the cell compatibility of these hydrogel carriers. Together, these results make salecan-incorporated PAM hydrogels promising materials for drug delivery.

Synthesis and characterization of a novel cationic hydrogel base on salecan-g-PMAPTAC.

Salecan is a biological macromolecular and biocompatible polysaccharide that has been investigated for recent years. Herein, we report a novel cationic hydrogel fabricated by graft-polymerizing 3-(methacryloylamino)propyl-trimethylammonium chloride (MAPTAC) onto salecan chains. The obtained hydrogels were transparent, solid-elastic, macro-porous, ion-sensitive, and non-cytotoxic. The swelling ratios increased with salecan content, while mechanical strength does the opposite. Moreover, drug delivery test was studied as a potential application. Diclofenac sodium (DS) and insulin were selected as model drugs. Interestingly, in drug loading process, DS molecules exhibited highly affinity to these cationic hydrogels. Almost all the DS molecules in loading solution were absorbed and spread into the hydrogel. For drug release profiles, insulin-loaded hydrogel showed an initial rapid release and a sustained release. As a comparison, DS-loaded hydrogel exhibited a more sustained release profile. Results suggested salecan-g-PMAPTAC hydrogel could be a good candidate for anionic drug loading and delivery.

A novel thermo-responsive hydrogel based on salecan and poly(N-isopropylacrylamide): synthesis and characterization.

Salecan is a novel microbial polysaccharide produced by Agrobacterium sp. ZX09. The salt-tolerant strain was isolated from a soil sample in our laboratory and the 16S rDNA sequence was deposited in the GenBank database under the accession number GU810841. Salecan is suitable to fabricate hydrogel for biomedical applications due to the excellent hydrophilicity and biocompatibility. Here, salecan has been introduced into poly(N-isopropylacrylamide) (PNIPAm) network to form novel thermo-sensitive semi-interpenetrating polymer networks (semi-IPNs). The structure of salecan/PNIPAm semi-IPNs was confirmed by Fourier transformation infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Thermogravimetric analysis (TGA) proved the stability of the semi-IPNs. Rheological and compressive tests revealed an elastic solid-like behavior and good mechanical properties of the hydrogels. Swelling behavior test showed the hydrogels possessed high water content at room temperature. An excellent thermo-sensitive property of fast response rates to temperature had been demonstrated as well. In vitro degradation measurements ensured the semi-IPNs were degradable. Cytotoxicity and cell adhesion study suggested the synthesized salecan/PNIPAm hydrogels were non-toxic and biocompatibility. The results indicated the novel thermo-responsive hydrogels could be a suitable candidate for biomedical applications.

Investigation of Salecan/poly(vinyl alcohol) hydrogels prepared by freeze/thaw method.

Salecan is a novel water-soluble extracellular-glucan produced by a new kind of salt-tolerant strain Agrobacterium sp. ZX09 and can be applied in food and medicine industries. In this work, Salecan (Sal) was incorporated into poly(vinyl alcohol) (PVA) to prepare novel Sal/PVA hybrid hydrogels by repeated freeze-thaw processing. Physicochemical and biological characteristics of the hydrogels were investigated to evaluate their potential as cell adhesion materials. By increasing the Salecan content in the hybrid hydrogels, their swelling capacity increased notably, while the compressive modulus decreased. Observed by SEM, Sal/PVA hydrogels had a homogeneous porous structure. The degradation rate of the hydrogels can be controlled by tailoring the composition ratio of Sal/PVA. Furthermore, cells could adhere well on the surface of Sal/PVA hydrogels. In conclusion, these results make Sal/PVA hydrogels attractive materials for biomedical applications.

Synthesis and characterization of a novel pH-thermo dual responsive hydrogel based on salecan and poly(N,N-diethylacrylamide-co-methacrylic acid).

Salecan is a water-soluble microbial polysaccharide produced by Agrobacterium sp. ZX09, a salt-tolerant strain isolated from a soil sample in our laboratory. Previous work inspired us salecan is a good candidate to fabricate hydrogels. Poly(N,N-diethylacrylamide) is one type of thermo sensitive polymer which is not investigated extremely as poly(N-isopropylacrylamide). Here, we report a novel pH-thermo dual responsive hydrogel based on salecan and poly(N,N-diethylacrylamide-co-methacrylic acid) semi-interpenetrating polymer networks (semi-IPNs). The physicochemical property of this hydrogel was investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA), rheological test and Scanning Electron Microscopy (SEM). It was interesting that the storage modulus (G') and pore size of the hydrogel could be tuned by adjusting the content of salecan and crosslinker. The pH-thermo dual responsive property was demonstrated by swelling behavior test: the swelling ratio of the hydrogel decreased continuously as the temperature increased from 25 °C to 37 °C, while it was pH-dependent as well. Especially, when exposed to a higher temperature (37 °C) and acidic environment (pH 4.0), drug-loaded hydrogel would have a quick release. Finally, the cytotoxicity of drug-free hydrogels was investigated on A549 and HepG2 cells, results showed that it was non-toxic while the DOX released from hydrogels had comparable cytotoxicity with respect to free DOX. In conclusion, the novel salecan/poly(N,N-diethylacrylamide-co-methacrylic acid) semi-interpenetrating polymer network hydrogels were pH-thermo dual responsive and may be a promising candidate for drug delivery system.

Synthesis and characterization of a novel semi-IPN hydrogel based on Salecan and poly(N,N-dimethylacrylamide-co-2-hydroxyethyl methacrylate).

Salecan is a novel water-soluble, high molecular mass extracellular ß-glucan produced by Agrobacterium sp. ZX09. Salecan has excellent physicochemical and biological properties, making it very suitable for hydrogel preparation. In this study, a series of novel semi-interpenetrating polymer network (semi-IPN) hydrogels containing Salecan and poly(N,N-dimethylacrylamide-co-2-hydroxyethylmethacrylate) (poly(DMAA-co-HEMA)) were synthesized by radical polymerization and semi-IPN technology. Structure and morphology of the hydrogels were characterized by FTIR, XRD, TGA and SEM. The semi-IPNs had a well-interconnected porous structure with tunable pore size ranging from 6 to 41µm. Swelling capability of the hydrogels was improved by introducing the hydrophilic Salecan. Rheological results indicated that the incorporation of poly(DMAA-co-HEMA) into hydrogels enhanced the storage modulus. Compression tests revealed that these semi-IPNs were robust materials with compressive modulus between 13.3 and 90.5kPa, the addition of Salecan increased the fracture strain from 71.1% to 88.8%. Degradation and cytotoxicity tests demonstrated that semi-IPNs were degradable and non-toxic.