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Antibodies are widely used both in clinical practice and in research. However, the development of methods to increase the ratio of antibodies to recognize phosphorylated proteins remains challenging. In this study, we report a novel and useful method for the efficient production of antibodies for phosphorylated proteins. Based on our previously developed vaccine adjuvant Nap-GDFDFDY, we prepared hydrogels by the Ca2+-induced self-assembly of a phosphorylated peptide gelator Nap-GDFDFpDY. The hydrogel could protect phosphorylated antigens from being dephosphorylated by endogenous phosphatase, thus selectively increasing the ratio of the antibodies for phosphorylated proteins. Our study provides a useful strategy for the production of antibodies to recognize proteins with specific posttranslational modifications.

Composite biomaterials offer a new approach for engineering novel, minimally-invasive scaffolds with properties that can be modified for a range of soft tissue applications. In this study, a new way of controlling the gelation of alginate hydrogels using Ga-based glass particles is presented. Through a comprehensive analysis, it was shown that the setting time, mechanical strength, stiffness and degradation properties of this composite can all be tailored for various applications. Specifically, the hydrogel generated through using a glass particle, wherein toxic aluminium is replaced with biocompatible gallium, exhibited enhanced properties. The material's stiffness matches that of soft tissues, while it displays a slow and tuneable gelation rate, making it a suitable candidate for minimally-invasive intra-vascular injection. In addition, it was also found that this composite can be tailored to deliver ions into the local cellular environment without affecting platelet adhesion or compromising viability of vascular cells in vitro., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Bacterial infection is one of main causes that threaten global human health. Especially, antibiotic-resistant bacteria like methicillin-resistant Staphylococcus aureus (MRSA) lead to high mortality rate and more expensive treatment cost. Here, a novel amino-acid-modified conjugated oligomer OTE-d-Phe was synthesized by modifying the side chain of conjugated oligo(thiophene ethynylene) with d-phenylalanine. By mixing 9-fluorenylmethyloxycarbonyl-l-phenylalanin (Fmoc-l-Phe) with OTE-d-Phe, a new and biocompatible low-molecular weight hydrogel (HG-2) was prepared through self-assembly. In solution, HG-2 can effectively capture bacteria spontaneously, such as Escherichia coli and MRSA. Most importantly, the hydrogel has specific and strong antibacterial activity against MRSA over methicillin-susceptible S. aureus, Staphylococcus epidermidis, and E. coli. Interestingly, when the hydrogel was put on a model surface, a piece of cloth, it also is able to selectively kill MRSA with low cell cytotoxicity. The antibacterial mechanism was investigated, and it demonstrated that the HG-2 interacts with and physically breaks the cell wall and membrane, which leads to MRSA death. Therefore, this new conjugated oligomer-based hydrogel provides promising applications in disinfection and therapy of MRSA in hospital and in community.

Three-dimensional (3D) tissue models replicating liver architectures and functions are increasingly being needed for regenerative medicine. However, traditional studies are focused on establishing 2D environments for hepatocytes culture since it is challenging to recreate biodegradable 3D tissue-like architecture at a micro scale by using hydrogels. In this paper, we utilized a gelatin methacryloyl (GelMA) hydrogel as a matrix to construct 3D lobule-like microtissues for co-culture of hepatocytes and fibroblasts. GelMA hydrogel with high cytocompatibility and high structural fidelity was determined to fabricate hepatocytes encapsulated micromodules with central radial-type hole by photo-crosslinking through a digital micromirror device (DMD)-based microfluidic channel. The cellular micromodules were assembled through non-contact pick-up strategy relying on local fluid-based micromanipulation. Then the assembled micromodules were coated with fibroblast-laden GelMA, subsequently irradiated by ultraviolet for integration of the 3D lobule-like microtissues encapsulating multiple cell types. With long-term co-culture, the 3D lobule-like microtissues encapsulating hepatocytes and fibroblasts maintained over 90% cell viability. The liver function of albumin secretion was enhanced for the co-cultured 3D microtissues compared to the 3D microtissues encapsulating only hepatocytes. Experimental results demonstrated that 3D lobule-like microtissues fabricated by GelMA hydrogels capable of multicellular co-culture with high cell viability and liver function, which have huge potential for liver tissue engineering and regenerative medicine applications.

A 3D hydrogel layer is probed by combining surface plasmon resonance with optical waveguide spectroscopy to detect biomolecules. A template terpolymer P(DMAAm-co-DMIAAm-co-VDMA) is synthesized via reversible addition-fragmentation chain-transfer polymerization. The terpolymer is then modified with an amino group bearing biotin to enable biomolecular recognition for streptavidin. A hydrogel thin layer is prepared onto a gold surface after spin-coating and photo-crosslinking of the modified polymer. Finally, the hydrogel is utilized to quantitatively detect streptavidin by using surface plasmon resonance-optical waveguide spectroscopy measurements., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Self-healing hydrogels based on metal-ligand coordination chemistry provide new and exciting properties that improve injectability, rheological behaviors, and even biological functionalities. The inherent reversibility of coordination bonds improves on the covalent cross-linking employed previously, allowing for the preparation of completely self-healing hydrogels. In this article, recent advances in the development of this class of hydrogels are summarized and their applications in biology and medicine are discussed. Various chelating ligands such as bisphosphonate, catechol, histidine, thiolate, carboxylate, pyridines (including bipyridine and terpyridine), and iminodiacetate conjugated onto polymeric backbones, as well as the chelated metal ions and metal ions containing inorganic particles, which are used to form dynamic networks, are highlighted. This article provides general ideas and methods for the design of self-healing hydrogel biomaterials based on coordination chemistry., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Alginate hydrogel particles are promising delivery systems for protein encapsulation and controlled release because of their excellent biocompatibility, biodegradability, and mild gelation process. In this study, a facile microfluidic approach is developed for making uniform core-shell hydrogel microparticles. To address the challenge of protein retention within the alginate gel matrix, poly(ethyleneimine) (PEI)- and chitosan-coated alginate microparticles were fabricated demonstrating improved protein retention as well as controlled release. Furthermore, a model protein ovalbumin was loaded along with delta inulin microparticulate adjuvant into the water-core of the alginate microparticles. Compared to those microparticles with only antigen loaded, the antigen + adjuvant loaded microparticles showed a delayed and sustained release of antigen. This microfluidic approach provides a convenient method for making well-controlled alginate microgel particles with uniform size and controlled properties, and demonstrates the ability to tune the release profiles of proteins by engineering microparticle structure and properties., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Herein, we report the successful synthesis of a series of poly (N-isopropylacrylamide) (PNIPA)/layered double hydroxides (LDHs)/nano-hydroxyapatite (nano-HA) hydrogels via in-situ radical polymerization. The internal morphology, thermo sensitivity, rheological properties, swelling behavior and hemocompatibility of the PNIPA/LDHs/HA composite hydrogels were systematically investigated. Results show that the hydrogels had a reversible sol-gel transformation around 33 °C. Interactions between the positively charged LDHs and negatively charged nano-HA particles created a highly porous hydrogel network. The composite hydrogels exhibited excellent hemocompatibility, incredible mechanical toughness and reversible swelling/deswelling behavior. To our knowledge, this is the first reported study to use two types of inorganic nanoparticle with opposing charges as hydrogel crosslinking agents. Based on its properties, we expect this hydrogel has broad applications potential in tissue engineering, drug delivery and biosensor development., (Copyright © 2018 Elsevier Inc. All rights reserved.)

In this study, a simple yet versatile method is introduced to prepare a hyperbranched supramolecular polymer hydrogel by utilizing Type II photoinitiated self-condensing vinyl polymerization of N-acryloyl glycinamide, which can serve not only as an inimer providing branching sites, but also as a hydrogen-bonding cross-linker. The hyperbranched poly(N-acryloyl glycinamide) (HB-PNAGA) hydrogels demonstrate excellent mechanical performances with a tensile strength of 0.793-2.724 MPa, elongation at break of 203-902%, Young's modulus of 0.450-1.172 MPa, and maximal fracture energy of 2200 J m -2 , which are all superior to those of linear PNAGA hydrogels. The results indicate that the HB-PNAGA hydrogel is very stiff and tough due to much higher H-bonding cross-linking density formed in hyperbranched architecture. The high stiffness, toughness, and ease of preparation make these hyperbranched supramolecular hydrogels very attractive for application as soft supporting tissue replacements., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A highly competent material, based on poly lactic acid (PLLA) grafted hydroxypropyl guar gum (HPG-g-PLLA) and polypyrrole/carboxylated multiwalled carbon nanotube (PPy/C-MWCNT) composite of various binary composition and copolymer of one of these nanocomposites have been synthesized successfully by in-situ polymerization. The environmentally affable nanocomposites have been characterized by spectroscopy, microscopy and thermogravimetry. Cytotoxicity of bio-nanocomposite has been inquired by cell viability study, which reveals its eco-friendly nature. The electrochemical properties of the biomaterials have been appraised by cyclic voltammetric studies. The PPy/C-MWCNT composite having 1 wt% C-MWCNT appears as the optimum composition from electrochemical studies. The hydrogel nanocomposite (HPG-g-PLLA 5/0.5 ) copolymer behaves as a super ordinate material than pure PPy and PPy/C-MWCNT in every aspect of electrochemical properties like current density, stability, processibility and reversibility. Moreover the hydrogel nanocomposite, making electrode fabrication more simple and binder-free, nullifies all the interfacial complications arising from binders as well., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Extremely compressible hydrogels are fabricated in one pot via sulfonic-acid-modified graphitic carbon nitride (g-CN-AHPA) as a visible light photoinitiator and reinforcer. The hydrogels show unusual compressibility upon applied stress up to 12 MPa, presenting temporary physical deformation, and remain undamaged after stress removal despite their high water content (90 wt%). Cyclic compressibility proves the fatigue resistance of the covalently and electrostatically reinforced system that possesses tissue adhesive properties, shock resistance, cut resistance, and little to no toxicity., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Simplifying synthesis and administration process, improving photothermal agents' accumulation in tumors, and ensuring excellent biocompatibility and biodegradability are keys to promoting the clinical application of photothermal therapy. However, current photothermal agents have great difficulties in meeting the requirements of clinic drugs from synthesis to administration. Herein, we reported the in situ formation of a Ca 2+ /Mg 2+ stimuli-responsive ICG-alginate hydrogel in vivo for localized tumor photothermal therapy. An ICG-alginate hydrogel can form by the simple introduction of Ca 2+ /Mg 2+ into ICG-alginate solution in vitro, and the widely distributed divalent cations in organization in vivo enabled the in situ fabrication of the ICG-alginate hydrogel without the leakage of any agents by simple injection of ICG-alginate solution into the body of mice. The as-prepared ICG-alginate hydrogel not only owns good photothermal therapy efficacy and excellent biocompatibility but also exhibits strong ICG fixation ability, greatly benefiting the high photothermal agents' accumulation and minimizing the potential side effects induced by the diffusion of ICG to surrounding tissues. The in situ-fabricated ICG-alginate hydrogel was applied successfully in highly efficient PTT in vivo without obvious side effects. Besides, the precursor of the hydrogel, ICG and alginate, can be stored in a stable solid form, and only simple mixing and noninvasive injection are needed to achieve PTT in vivo. The proposed in situ gelation strategy using biocompatible components lays down a simple and mild way for the fabrication of high-performance PTT agents with the superiors in the aspects of synthesis, storage, transportation, and clinic administration.

Cell or tissue stretching and strain are present in any in vivo environment, but is difficult to reproduce in vitro. Here, we describe a simple method for casting a thin (about 500 μm) and soft (about 0.3 kPa) hydrogel of gelatin and a method for characterizing the mechanical properties of the hydrogel simply by changing pressure with a water column. The gelatin is crosslinked with mTransglutaminase and the area of the resulting hydrogel can be increased up 13-fold by increasing the radial water pressure. This is far beyond physiological stretches observed in vivo. Actuating the hydrogel with a radial force achieves both information about stiffness, stretchability, and contractability, which are relevant properties for tissue engineering purposes. Cells could be stretched and contracted using the gelatin membrane. Gelatin is a commonly used polymer for hydrogels in tissue engineering, and the discovered reversible stretching is particularly interesting for organ modeling applications., (© 2018 Wiley Periodicals, Inc.)

This study reports an effective method for controlling substance-release sites of hydrogel. Glycidyl methacrylate, which contains two functional groups, namely, double-bond acrylate and epoxide, is photografted on a hydrogel surface through hydrogen abstraction photopolymerization due to the existence of a hydrogen donor, such as an amine, in the hydrogel matrix. The remaining epoxide group crosslinks the polymer chain of polyglycidyl methacrylate. Substance release of hydrogel is changed due to the altered surface texture of hydrogel. Rate and site-controlled substance release are achieved by controlling the thickness and site of surface grafting and the extent of epoxide ring opening. This study may provide a novel method for achieving hydrogel function or modified performance of other biomaterials to meet biological activity requirements., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A versatile double-network (DN) hydrogel with two noncovalent crosslinked networks is synthesized by multiple hydrogen bonding (H-bonding) interactions. The DN hydrogels are synthesized via a heating-cooling photopolymerization process by adding all reactants of agar, N-acryloyl glycinamide (NAGA) and N-benzylacrylamide (NBAA) monomers, UV initiators to a single water pot. Poly(N-acryloyl glycinamide-co-N-benzyl acrylamide) (P(NAGA-co-NBAA)) with a triple amide in one side group is synthesized via UV-light polymerization between NAGA and NBAA, forming a strong intermolecular H-bonding network. Meanwhile, the intramolecular H-bonding network is formed between P(NAGA-co-NBAA) and agars. The sol-gel phase transition of agars at 86 °C generates the molecular entanglement network. Such a double network enables the hydrogel high self-healing efficiency (about 95%), good shape memory ability, and high mechanical strength (1.1 MPa). Additionally, the DN hydrogel is completely crosslinked by multiple hydrogen bonds (H-bonds) and the physical crosslinking of agar without extra potential toxic chemical crosslinker. The DN hydrogels find extensive applications in the biomedical materials due to their excellent biocompatibility., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Silk fibroin (SF) hydrogel is a promising candidate in biomaterial field; however its application is quite limited by long-gelation time. In the present study, we developed a novel strategy named soft freezing to accelerate the process and control the sol-gel transition of SF protein. SF protein was induced to self-assembly by soft freezing process for achieving the reconstructed SF solution with metastable structure. It was found that the soft freezing process triggers the structural transition from random structure to ordered structure-rich conformation. Gelation kinetics showed that the gelation time of SF protein could be regulated by changing freezing time and initial concentration. The reconstructed SF solution allowed enhanced sol-gel transition within 6 hours, even at extremely low concentration. The attractive features of the method described here include the accelerated gelation, free of chemical agents, and reducing processing complexity. The SF solution with short gelation time will be applicable as cell encapsulation and injectable applications for tissue engineering and regenerative medicine, which greatly expand the applications of SF hydrogels., (Copyright © 2018 Elsevier B.V. All rights reserved.)

As the use of low-molecular-weight gelators (LMWGs) as components in single and multicomponent systems for optoelectronic and solar cell applications increases, so does the need for more functional gelators. There are relatively few examples of p-type gelators that can be used in such systems. Here, the synthesis and characterization of three amino-acid-functionalized p-type gelators based on terthiophene, tetrathiafulvalene, and oligo(phenylenevinylene) are described. The cores of these molecules are already used as electron donors in optoelectronic applications. These newly designed molecules can gel water to form highly organized structures, which can be dried into thin films that show p-type behavior., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In tissue engineering there is growing interest in fabricating highly engineered platforms designed to instruct cells towards the synthesis of tissues that reproduce their natural counterpart. In this context, a fundamental factor to take into account is the control over the final tissue orientation, especially for what concerns the replication of load-bearing tissues whose functions are strictly related to their microstructural organization. Starting from this point, in this work we have engineered a gelatin-based hydrogel in order to be patterned by 2-photon polymerization (2PP) lithography for the fabrication of instructive free standing building blocks designed to produce anisotropic collagen-based μtissues. Biological results clearly highlighted the strong relationship between μtissue orientation and such topographies, which resulted in a crucial element in the production of highly anisotropic μtissues.

The development of microengineered hydrogels co-cultured with cells in vitro could advance in vivo bio-systems in both structural complexity and functional hierarchy, which holds great promise for applications in regenerative tissues or organs, drug discovery and screening, and bio-sensors or bio-actuators. Traditional hydrogel microfabrication technologies such as ultraviolet (UV) laser or multiphoton laser stereolithography and three-dimensional (3D) printing systems have advanced the development of 3D hydrogel micro-structures but need either expensive and complex equipment, or harsh material selection with limited photoinitiators. Herein, we propose a simple and flexible hydrogel microfabrication method based on a ubiquitous visible-light projection system combined with a custom-designed photosensitive microfluidic chip, to rapidly (typically several to tens of seconds) fabricate various two-dimensional (2D) hydrogel patterns and 3D hydrogel constructs. A theoretical layer-by-layer model that involves continuous polymerizing-delaminating-polymerizing cycles is presented to explain the polymerization and structural formation mechanism of hydrogels. A large area of hydrogel patterns was efficiently fabricated without the usage of costly laser systems or photoinitiators, i.e., a stereoscopic mesh-like hydrogel network with intersecting hydrogel micro-belts was fabricated via a series of dynamic-changing digital light projections. The pores and gaps of the hydrogel network are tunable, which facilitates the supply of nutrients and discharge of waste in the construction of 3D thick bio-models. Cell co-culture experiments showed the effective regulation of cell spreading by hydrogel scaffolds fabricated by the new method presented here. This visible light enabled hydrogel microfabrication method may provide new prospects for designing cell-based units for advanced biomedical studies, e.g., for 3D bio-models or bio-actuators in the future.

Compositional and structural patterns play a crucial role in the function of many biological tissues. In the present work, for nanofibrillar hydrogels formed by chemically cross-linked cellulose nanocrystals (CNC) and gelatin, we report a microextrusion-based 3D printing method to generate structurally anisotropic hydrogel sheets with CNCs aligned in the direction of extrusion. We prepared hydrogels with a uniform composition, as well as hydrogels with two different types of compositional gradients. In the first type of gradient hydrogel, the composition of the sheet varied parallel to the direction of CNC alignment. In the second hydrogel type, the composition of the sheet changed orthogonally to the direction of CNC alignment. The hydrogels exhibited gradients in structure, mechanical properties, and permeability, all governed by the compositional patterns, as well as cytocompatibility. These hydrogels have promising applications for both fundamental research and for tissue engineering and regenerative medicine.

Synthetic hydrogel materials can recapitulate the natural cell microenvironment; however, it is equally necessary that the gels maintain cell viability and phenotype while permitting reisolation without stress, especially for use in the stem cell field. Here, we describe a family of synthetically accessible, squaramide-based tripodal supramolecular monomers consisting of a flexible tris(2-aminoethyl)amine (TREN) core that self-assemble into supramolecular polymers and eventually into self-recovering hydrogels. Spectroscopic measurements revealed that monomer aggregation is mainly driven by a combination of hydrogen bonding and hydrophobicity. The self-recovering hydrogels were used to encapsulate NIH 3T3 fibroblasts as well as human-induced pluripotent stem cells (hiPSCs) and their derivatives in 3D. The materials reported here proved cytocompatible for these cell types with maintenance of hiPSCs in their undifferentiated state essential for their subsequent expansion or differentiation into a given cell type and potential for facile release by dilution due to their supramolecular nature.

Salecan is a novel water-soluble extracellular β-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 Fe 3 O 4 @Agarose nanoparticles for drug release testing. Vibrating sample magnetometer characterization verified that integration of Fe 3 O 4 @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)/Fe 3 O 4 @Agarose hydrogels were well-suited for magnetically targeted drug delivery systems., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Sustained delivery of protein therapeutics is limited owing to the fragile nature of proteins. Despite its great potential, delivery of proteins without any loss of bioactivity remains a challenge in the use of protein therapeutics in the clinic. To surmount this shortcoming, we report a pH- and temperature-responsive in situ-forming injectable hydrogel based on comb-type polypeptide block copolymers for the controlled delivery of proteins. Polypeptide block copolymers, composed of hydrophilic polyethylene glycol (PEG), temperature-responsive poly(γ-benzyl-l-glutamate) (PBLG), and pH-responsive oligo(sulfamethazine) (OSM), exhibit pH- and temperature-induced sol-to-gel transition behavior in aqueous solutions. Polypeptide block copolymers were synthesized by combining N-carboxyanhydride-based ring-opening polymerization and post-functionalization of the chain-end using N-hydroxy succinimide ester activated OSM. The physical properties of polypeptide-based hydrogels were tuned by varying the composition of temperature- and pH-responsive PBLG and OSM in block copolymers. Polypeptide block copolymers were non-toxic to human embryonic kidney cells at high concentrations (2000 μg mL -1 ). Subcutaneous administration of polypeptide block copolymer sols formed viscoelastic gel instantly at the back of Sprague-Dawley (SD) rats. The in vivo gels exhibited sustained degradation and were found to be bioresorbable in 6 weeks without any noticeable inflammation at the injection site. Anionic characteristics of hydrogels allow efficient loading of a cationic model protein, lysozyme, through electrostatic interaction. Lysozyme-loaded polypeptide block copolymer sols readily formed a viscoelastic gel in vivo and sustained lysozyme release for at least a week. Overall, the results demonstrate an elegant approach to control the release of certain charged proteins and open a myriad of therapeutic possibilities in protein therapeutics.

Visible light-induced hydrogelation is attractive for various biomedical applications. In this study, hydrogels of alginate with phenolic hydroxyl groups (Alg-Ph) were obtained by irradiating a solution containing the polymer, ruthenium II trisbipyridyl chloride ([Ru(bpy) 3 ] 2+ ) and sodium persulfate (SPS), with visible light. The hydrogelation kinetics and the mechanical properties of the resultant hydrogels were tunable by controlling the intensity of the light and the concentrations of [Ru(bpy) 3 ] 2+ and SPS. With appropriate concentrations of [Ru(bpy) 3 ] 2+ and SPS, the hydrogel could be obtained following approximately 10 s of irradiation using a normal desktop lamp. The hydrogelation process and the resultant hydrogel were cytocompatible; mouse fibroblast cells enclosed in the Alg-Ph hydrogel maintained more than 90% viability for 1 week. The solution containing Alg-Ph, [Ru(bpy) 3 ] 2+ and SPS was useful as a bioink for stereolithographic bioprinting. Cell-laden hydrogel constructs could be printed using the bioprinting system equipped with a visible light projector without a significant decrease in cell viability in the presence of photoabsorbent Acid Red 18. The hydrogel construct including a perfusable helical lumen of 1 mm in diameter could be fabricated using the printing system. These results demonstrate the significant potential of this visible light-induced hydrogelation system and the stereolithographic bioprinting using the hydrogelation system for tissue engineering and regenerative medicine.

The physico-chemical properties of a chitosan and polyvinyl alcohol (CS/PVA)-based hydrogel composite were investigated. Tetraethyl orthosilicate (TEOS) was employed as a crosslinking agent. The results indicated that the chitosan-based composite presented a thermal resistance up to 200°C. The structural properties, which were evaluated using FTIR and DSC, showed good miscibility between chitosan and polyvinyl alcohol. SEM presented a compact and homogeneous structure. The release profile of the chitosan-based hydrogel composite was investigated using gallic acid (GA). It showed high antioxidant activities, which were monitored using DPPH radical scavenging. Diffusion of water into the chitosan-based hydrogel was assumed to be pseudo-Fickian in PBS solution. The CS/PVA-based hydrogel composite exhibited good properties as a drug delivery system., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Islet transplantation has the potential of reestablishing naturally-regulated insulin production in Type 1 diabetic patients. Nevertheless, this procedure is limited due to the low islet survival after transplantation and the lifelong immunosuppression to avoid rejection. Islet embedding within a biocompatible matrix provides mechanical protection and a physical barrier against the immune system thus, increasing islet survival. Alginate is the preferred biomaterial used for embedding insulin-producing cells because of its biocompatibility, low toxicity and ease of gelation. However, alginate gelation is poorly controlled, affecting its physicochemical properties as an injectable biomaterial. Including different concentrations of the phosphate salt Na 2 HPO 4 in alginate hydrogels, we can modulate their gelation time, tuning their physicochemical properties like stiffness and porosity while maintaining an appropriate injectability. Moreover, these hydrogels showed good biocompatibility when embedding a rat insulinoma cell line, especially at low Na 2 HPO 4 concentrations, indicating that these hydrogels have potential as injectable biomaterials for Type 1 Diabetes Mellitus treatment., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

In situ cross-linked hyaluronan (HA) hydrogels with different capacities for biomineralization were prepared and their enzymatic degradation was monitored. Covalent incorporation of bisphosphonates (BPs) into HA hydrogel results in the increased stiffness of the hydrogel in comparison with the unmodified HA hydrogel of the same cross-linking density. The rate of enzymatic degradation of HABP hydrogel was significantly lower than the rate of degradation of control HA hydrogel in vitro. This effect is observed only in the presence of calcium ions that strongly bind to the matrix-anchored BP groups and promote further mineralization of the matrix. The degradation of the hydrogels was followed by noninvasive fluorescence measurements enabled after mild and chemoselective labeling of cross-linkable HA derivatives with a fluorescent tag., (© 2017 Wiley Periodicals, Inc.)

Sensitivity enhancement and proteins adsorption are the common challenges faced in protein immunoassays. In this work, an ultrasensitive and protein-resistant label-free amperometric immunosening platform for carcinoma antigen-125 (CA125) based on redox polyaniline-polythionine hydrogel (PANI-PThi gel) was developed. The as-prepared hydrogel, which was facilely synthesized by electropolymerization, exhibited good conductivity and strong hydrophilicity while the sensitivity and specificity of the immunosensor can be enhanced. Furthermore, the as-prepared AuNPs functionalized PANI-PThi gel exhibited strong current signal and H 2 O 2 electrocatalytic ability, which guaranteed a large current variable range. Based on these, the prepared immunosensor revealed a wide linear range from 0.0001 U mL -1 to 1 kU mL -1 , a limit of detection of 0.00125 U mL -1 and its sensitivity was at least three-fold higher than previous works. More importantly, the prepared immunosensor exhibited excellent specificity, making it capable of assaying CA125 in human serum., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: In this study, central composite design was utilized for the optimization of genipin cross-linked chitosan/Eudragit®-L 100 interpenetrating hydrogel network films fabricated through solvent evaporation technique., Methods: Hydrogel formulations were studied using response surface methodology; regression analysis and the surface plots were used to evaluate the effect of variables on T50% (the time for 50% of drug release) and dynamic swelling with optimum formulation selection. Initial burst release of drug was observed from the formulated hydrogels during the first 2 hours of dissolution at simulated gastric pH 1.2 and then slow release during the next 10 hours in the simulated intestinal fluid at pH 7.4. Different polymer ratios in formulation showed significant influence on T50% and dynamic swelling of hydrogel. The highest T50% was observed at 9.89 hour and dynamic swelling at 7.86 h., Result: It was observed that by changing the polymer ratio with cross-linker, release rate of metformin could be modified. Cross-linker also affects drug release rate, i.e. the release rate is decreased with the increase in its concentration. The physical state of hydrogel was investigated by scanning electron microscope., Conclusion: It indicated the uniform distribution of drug in hydrogel matrix system. Moreover, the presence of hydrogen and ionic bonds between polymers and crosslinking agent formed interpenetrating hydrogel network, likely responsible for increased value of T50%, as confirmed by FTIR. Acute oral toxicity study was performed to investigate the toxic effect of crosslinking agent and polymer used in formulations., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

In this study, La 3+ (ion)/La(OH) 3 -W/La(OH) 3 -EW-loaded magnetic cationic hydrogel (MCH) composites were fabricated in situ and characterized to investigate the effects of lanthanum species on phosphate adsorption. The corresponding maximum P adsorption capacities of MCH-loaded La 3+ (ion) (MCH-La 3+ (ion)), La(OH) 3 -W (MCH-La(OH) 3 -W), and La(OH) 3 -EW (MCH-La(OH) 3 -EW) were 70.5 ± 2.67, 69.2 ± 3.5, and 90.2 ± 2.9 mg P/g, respectively. Furthermore, for MCH-La(OH) 3 -EW, the P adsorption capacity was maintained relatively stable and high at pH 4.5-11 because of the ligand exchange, electrostatic interactions, and Lewis acid-base interactions. The enhanced adsorption of P was achieved over a wide pH range, as well as in the presence of competing anions (including Cl - , NO 3 - , SO 4 2- , HCO 3 - and SiO 4 4- ). Moreover, the exhausted MCH-La(OH) 3 -EW could be easily regenerated by a NaOH-NaCl desorption agent with above 72% adsorption capacity remained during five recycles. The column adsorption capacity of MCH-La(OH) 3 -EW reached ∼3500 bed volumes (BV) (∼67.7 mg P/g) as the concentration of P decreased from 5 mg/L to 0.1 mg/L. The ATR-IR, Raman, and XPS deconvolution results revealed that both MCH and lanthanum compounds, including La 3+ (ion), La(OH) 3 -W and La(OH) 3 -EW, contributed to the phosphate adsorption because of the electrostatic interactions between -N + (CH 3 ) 3 and phosphate, as well as the formation of LaPO 4 ·xH 2 O., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Peptide self-assembly is a facile route to the development of bioorganic hybrid materials that have sophisticated nanostructures toward diverse applications. Here, we report the synthesis of self-assembled peptide (Fmoc-diphenylalanine, Fmoc-FF)/graphitic carbon nitride (g-C 3 N 4 ) hydrogels for light harvesting and biomimetic photosynthesis through noncovalent interactions between aromatic rings in Fmoc-FF nanofibers and tris-s-triazine in g-C 3 N 4 nanosheets. According to our analysis, the photocurrent density of the Fmoc-FF/g-C 3 N 4 hydrogel was 1.8× higher (0.82 μA cm -1 ) than that of the pristine g-C 3 N 4 . This is attributed to effective exfoliation of g-C 3 N 4 nanosheets in the Fmoc-FF/g-C 3 N 4 network, facilitating photoinduced electron transfers. The Fmoc-FF/g-C 3 N 4 hydrogel reduced NAD + to enzymatically active NADH under light illumination at a high rate of 0.130 mol g -1 h -1 and drove light-responsive redox biocatalysis. Moreover, the Fmoc-FF/g-C 3 N 4 scaffold could well-encapsulate key photosynthetic components, such as electron mediators, cofactors, and enzymes, without noticeable leakage, while retaining their functions within the hydrogel. The prominent activity of the Fmoc-FF/g-C 3 N 4 hydrogel for biomimetic photosynthesis resulted from the easy transfer of photoexcited electrons from electron donors to NAD + via g-C 3 N 4 and electron mediators as well as the hybridization of key photosynthetic components in a confined space of the nanofiber network.

Self-assembled peptide-based hydrogels are emerging materials that have been exploited for wound healing, drug delivery, tissue engineering, and other applications. In comparison to synthetic polymer hydrogels, supramolecular peptide-based gels have advantages in biocompatibility, biodegradability, and ease of synthesis and modification. Modification of the emergent viscoelasticity of peptide hydrogels in a stimulus responsive fashion is a longstanding goal in the development of next-generation materials. In an effort to selectively modulate hydrogel viscoelasticity, we report herein a method to enhance the elasticity of β-sheet peptide hydrogels using specific molecular recognition events between functionalized hydrogel fibrils and biomolecules. Two distinct biomolecular recognition strategies are demonstrated: oligonucleotide Watson-Crick duplex formation between peptide nucleic acid (PNA) modified fibrils with a bridging oligonucleotide and protein-ligand recognition between mannose modified fibrils with concanavalin A. These methods to modulate hydrogel elasticity should be broadly adaptable in the context of these materials to a wide variety of molecular recognition partners.

Growing cells within an extracellular matrix-like 3D gel is required for, or can improve, the growth of many cell types ex vivo. Here, we describe a protocol for the generation of well-defined matrices for the culture of intestinal stem cells (ISCs) and intestinal organoids. These matrices comprise a poly(ethylene glycol) (PEG) hydrogel backbone functionalized with minimal adhesion cues including RGD (Arg-Gly-Asp), which is sufficient for ISC expansion, and laminin-111, which is required for organoid formation. As such, the hydrogels present a defined and reproducible, but also tunable, environment, allowing researches to manipulate physical and chemical parameters, and examine their influence on ISC and organoid growth. Hydrogels are formed by an enzymatic cross-linking reaction of multiarm PEG precursors bearing glutamine- and lysine-containing peptides. PEG precursors containing either stable or hydrolytically degradable moieties are used to produce mechanically softening hydrogels, which are used for the expansion of ISCs or the formation of organoids, respectively. We also provide protocols for immunofluorescence analysis of cellular structures grown within these matrices, as well as for their dissociation and retrieval of cells for downstream use. Hydrogel precursors can be produced and their mechanical properties characterized to ascertain stiffness within 5-7 d. Hydrogel formation for ISC expansion or organoid formation takes 1-2 h. The materials described here can be readily adapted for the culture of other types of normal or transformed organoid structures.

Objective: This study was aimed to enhance aqueous solubility of dexibuprofen through designing β-cyclodextrin (βCD) hydrogel nanoparticles and to evaluate toxicological potential through acute toxicity studies in rats., Significance: Dexibuprofen is a non-steroidal analgesic and anti-inflammatory drug that is one of safest over the counter medications. However, its clinical effectiveness is hampered due to poor aqueous solubility., Methods: βCD hydrogel nanoparticles were prepared and characterized by percent yield, drug loading, solubilization efficiency, FTIR, XRD, DSC, FESEM and in-vitro dissolution studies. Acute oral toxicity study was conducted to assess safety of oral administration of prepared βCD hydrogel nanoparticles., Results: βCD hydrogel nanoparticles dramatically enhanced the drug loading and solubilization efficiency of dexibuprofen in aqueous media. FTIR, TGA and DSC studies confirmed the formation of new and a stable nano-polymeric network and interactions of dexibuprofen with these nanoparticles. Resulting nanoparticles were highly porous with 287 nm in size. XRD analysis revealed pronounced reduction in crystalline nature of dexibuprofen within nanoparticles. Release of dexibuprofen in βCD hydrogel nanoparticles was significantly higher compared with dexibuprofen tablet at pH 1.2 and 6.8. In acute toxicity studies, no significant changes in behavioral, physiological, biochemical or histopathologic parameters of animals were observed., Conclusions: The efficient preparation, high solubility, excellent physicochemical characteristics, improved dissolution and non-toxic βCD hydrogel nanoparticles may be a promising approach for oral delivery of lipophilic drugs.

The authors introduce poly(ethylene glycol) (PEG) based macromonomers containing acid-labile ketal moieties as well as terminal methacrylate units that are amenable to radical polymerization. The synthesis of PEGs of different molecular weights (ranging from 2000 to 13 000 g mol -1 with polydispersities <1.15) with a central ketal unit (PEG-ketal-diol) and their conversion to PEG-ketal-dimethacrylates (PEG-ketal-DMA) is introduced. Degradation rates of both PEG-ketal-diols and PEG-ketal-DMA are investigated by in situ 1 H NMR kinetic studies in deuterated phosphate buffer. Hydrogels containing 0, 5, or 10 wt% of PEG-ketal-DMA and 100, 95, or 90 wt% of PEG-DMA, respectively, are synthesized and disintegration of the gels is investigated in buffer at different pH values. Visible disintegration of the gels appears at pH 5 for hydrogels containing PEG-ketal-DMA, whereas no visible degradation is observed at all at neutral pH or for PEG hydrogels without PEG-ketal-DMA., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Cartilage tissue regeneration often presents a challenging clinical situation. Recently, it has been shown that Periodontal Ligament Stem Cells (PDLSCs) possess high chondrogenic differentiation capacity. In this study, we developed a stem cell delivery system based on alginate/hyaluronic acid (HA) loaded with TGF-β1 ligand, encapsulating PDLSCs; and investigated the chondrogenic differentiation of encapsulated cells in alginate/HA hydrogel microspheres in vitro and in vivo. The results showed that PDLSCs, as well as human bone marrow mesenchymal stem cells (hBMMSCs), as the positive control, were stained positive for both toluidine blue and alcian blue staining, while exhibiting high levels of gene expression related to chondrogenesis (Col II, Aggrecan and Sox-9), as assessed via qPCR. The quantitative PCR analyses exhibited that the chondrogenic differentiation of encapsulated MSCs can be regulated by the modulus of elasticity of hydrogel delivery system, confirming the vital role of the microenvironment, and the presence of inductive signals for viability and differentiation of MSCs. In vivo, histological and immunofluorescence staining for chondrogenic specific protein markers confirmed ectopic cartilage-like tissue regeneration inside transplanted hydrogels. PDLSCs presented significantly greater capability for chondrogenic differentiation than hBMMSCs (P < 0.05). Altogether, our findings confirmed that alginate/HA hydrogels encapsulating PDLSCs are a promising candidate for cartilage regeneration.

A supramolecular hydrogel was formed by a simple mixing of solutions of nor-seco-cucurbit[10]uril (NS-CB[10]) and adamantylamine-terminated 4-armed polyethylene glycol (AdA-4-arm-PEG). In the formation of the hydrogel, NS-CB[10] acted as a noncovalent crosslinker to form a ternary complex with two AdA moieties. The dynamic and selective nature of the host-guest interaction between NS-CB[10] and AdA enabled the supramolecular hydrogel to rapidly recover its physical properties after it was damaged. In addition, the recovered hydrogel retained its physical properties with negligible differences from those of the pristine material, even after multiple self-healing cycles. The NS-CB[10]-based hydrogel with the self-healing property may be useful for various biological applications such as drug delivery, cell therapy and tissue engineering., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Electrospinning is a well-known technique for the preparation of scaffolds for biomedical applications. In this work, a continuous electrospinning method for gel fiber preparation is presented without a spinning window. As proof of concept, the preparation of poly(aspartic acid)-based hydrogel fibers and their properties are described by using poly(succinimide) as shell polymer and 2,2,4(2,4,4)-trimethyl-1,6-hexanediamine as cross-linker in the core of the nozzle. Cross-linking takes place as the two solutions get in contact at the tip of the nozzle. The impact of solution concentrations and feeding rates on fiber morphology, proof of the presence of cross-links as well as pH sensitivity after the transformation of the poly(succinimide)-based material to poly(aspartic acid) is presented., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In bone regenerative medicine there is a need for suitable bone substitutes. Hydrogels have excellent biocompatible and biodegradable characteristics, but their visco-elastic properties limit their applicability, especially with respect to 3D bioprinting. In this study, we modified the naturally occurring extracellular matrix glycosaminoglycan hyaluronic acid (HA), in order to yield photo-crosslinkable hydrogels with increased mechanical stiffness and long-term stability, and with minimal decrease in cytocompatibility. Application of these tailor-made methacrylated hyaluronic acid (MeHA) gels for bone tissue engineering and 3D bioprinting was the subject of investigation. Visco-elastic properties of MeHA gels, measured by rheology and dynamic mechanical analysis, showed that irradiation of the hydrogels with UV light led to increased storage moduli and elastic moduli, indicating increasing gel rigidity. Subsequently, human bone marrow derived mesenchymal stromal cells (MSCs) were incorporated into MeHA hydrogels, and cell viability remained 64.4% after 21 days of culture. Osteogenic differentiation of MSCs occurred spontaneously in hydrogels with high concentrations of MeHA polymer, in absence of additional osteogenic stimuli. Addition of bone morphogenetic protein-2 (BMP-2) to the culture medium further increased osteogenic differentiation, as evidenced by increased matrix mineralisation. MeHA hydrogels demonstrated to be suitable for 3D bioprinting, and were printed into porous and anatomically shaped scaffolds. Taken together, photosensitive MeHA-based hydrogels fulfilled our criteria for cellular bioprinted bone constructs within a narrow window of concentration.

There is a significant cost to mitigate the infection and inflammation associated with the implantable medical devices. The development of effective antibacterial and anti-inflammatory biomaterials with novel mechanism of action has become an urgent task. In this study, a supramolecular polymer hydrogel is synthesized by the copolymerization of N-acryloyl glycinamide and 1-vinyl-1,2,4-triazole in the absence of any chemical crosslinker. The hydrogel network is crosslinked through the hydrogen bond interactions between dual amide motifs in the side chain of N-acryloyl glycinamide. The prepared hydrogels demonstrate excellent mechanical properties-high tensile strength (≈1.2 MPa), large stretchability (≈1300%), and outstanding compressive strength (≈11 MPa) at swelling equilibrium state. A simulation study elaborates the changes of hydrogen bond interactions when 1-vinyl-1,2,4-triazole is introduced into the gel network. It is demonstrated that the introduction of 1-vinyl-1,2,4-triazole endowes the supramolecular hydrogels with self-repairability, thermoplasticity, and reprocessability over a lower temperature range for 3D printing of different shapes and patterns under simplified thermomelting extrusion condition. In addition, these hydrogels exhibit antimicrobial and anti-inflammatory activities, and in vitro cytotoxicity assay and histological staining following in vivo implantation confirm the biocompatibility of the hydrogel. These hydrogels with integrated multifunctions hold promising potential as an injectable biomaterial for treating degenerated soft supporting tissues., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel potassium oxalate-based hydrogel is proposed for treating dentin hypersensitivity and this study evaluates its in vitro performance as a remineralizing, desensitizing agent. Etched disks of human dentin were treated for 10 or 20 min using the test hydrogel, to mimic a professional application with dental mouth guards. Dentin disks were evaluated in terms of permeability indexes in a fluid-filled system, the surface morphology was assessed by scanning electron microscopy, and the structural properties were studied using X-ray diffraction analysis. The potassium oxalate hydrogel significantly reduced dentin permeability, in a time-dependent manner, and occluded most of the patent dentinal tubules via crystal precipitation, forming a remineralized layer. After hydrogel treatments, an acid solution (pH 4.2) was applied to the disks for 30 s, or 1, 2, or 5 min, in order to reproduce a plaque-like oral acidity, and further analysis showed a good resistance of the remineralized layer to the acid challenge. The potassium oxalate-based hydrogel showed a better performance over commercially available products and artificial saliva, appearing a promising candidate for the treatment of dentin hypersensitivity., (© 2017 Eur J Oral Sci.)

Vascularization is of great importance to adipose tissue regeneration. Here we introduced a paradigm that using scaffold to induce ASC spheroids, so to promote vascularized adipose tissue regeneration. Poly (l-glutamic acid) (PLGA) was activated by EDC, followed by being cross-linked by Adipic dihydrazide (ADH) to form a homogeneous hydrogel. Lyophilization was then carried out to create porous structure. The PLGA hydrogel scaffold possessed a significant swollen hydrophilic network to weaken cell-scaffold adhesion but drive ASCs to aggregate to form spheroids. Increase of seeding cell density was proved to result in the increase of spheroid size, upregulating angiogenic genes (VEGF and FGF-2) expression by enhancing the hypoxia-induced paracrine secretion. Also, the adipogenic differentiation of ASCs was achieved in spheroids in vitro. Moreover, the in vivo vascularized adipose tissue regeneration was evaluated in the dorsum of nude mice. After 12weeks post-implantation, the significant angiogenesis was found in both adipogenic induced and non-induced engineered tissue. In adipogenic induced group, the clear ring-like morphology, the large vacuole in the middle of the cell and the Oil red O staining demonstrated adipose tissue formation., Statement of Significance: Vascularization is of great importance to adipose tissue regeneration. Adipose derived stem cell (ASC) spheroids possessed not only the high efficiency of vascularization, but also the improved differentiation ability. Several research works have illustrated the advantage of ASC spheroids in vascularization. However, in adipose regeneration, ASC spheroid was rarely used. Even so, it is reasonable to believe that ASC spheroids hold a great promise in vascularized adipose tissue engineering. Thus in the present study, we introduced a method to create lots of ASC spheroids that acted as lots of individual adipogenesis and angiogenesis units inside of a porous hydrogel scaffold. Then, the scaffold carrying ASC spheroids was implanted subcutaneously in nude mice to preliminarily evaluate the adipose tissue generation and blood vessel formation., (Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Multi-functional supramolecular hydrogels have emerged as smart biomaterials for diverse biomedical applications. Here we report a multi-functional supramolecular hydrogel formed by the conjugate of the bioactive GRGDS peptide with biaryltetrazole that is the substrate of photo-click reaction. The hydrogel was used as a biocompatible matrix to encapsulate live cells for 3D culture. The presence of the RGD epitope in the hydrogelator enhanced the interaction of the nanofiber with integrin over-expressing cells, which resulted in the selective enhancement in the miRNA delivery into the encapsulated U87 cells. The intramolecular photo-click reaction of the biaryltetrazole moiety in the hydrogelator leads to a sensitive photo-response of the hydrogel, which allowed photo-degradation of the hydrogel for release of the encapsulated live cells for further bio-assay of the intracellular species.

A self-healing hydrogel is prepared by crosslinking acrylamide with a host-guest macro-crosslinker assembled from poly(β-cyclodextrin) nanogel and azobenzeneacrylamide. The photoisomerizable azobenzene moiety can change its binding affinity with β-cyclodextrin, therefore the crosslinking density and rheology property of the hydrogel can be tuned with light stimulus. The hydrogel can repair its wound autonomously through the dynamic host-guest interaction. In addition, the wounded hydrogel will lose its ability of self-healing when exposed to ultraviolet light, and the self-healing behavior can be recovered upon the irradiation of visible light. The utilizing of host-guest macro-crosslinking approach manifests the as-prepared hydrogel reversible and light-switchable self-healing property, which would broaden the potential applications of self-healing polymers., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Heparan sulfates are complex polysaccharides belonging to the family of glycosaminoglycans that participate to the regulation of cell behavior and tissue homeostasis. The biological activities conferred to heparan sulfates are largely dependent on the content and positioning of the sulfate groups along their saccharidic units. At present, identification of particular sulfation patterns in biologically relevant heparan sulfate sequences remains challenging. Although several approaches for structure analysis exist, the complexity of heparan sulfates makes new and original approaches still required. Here, we used molecular imprinting technologies to prepare a library of polyethylene glycol acrylate functionalized hydrogels with the aim to investigate their applicability as specific recognizing systems for fondaparinux, a synthetic pentasaccharide analog to the antithrombin binding site of heparin. Adequate choice of the hydrogel composition and controlling rebinding conditions were important determinants for improving the sulfated oligosaccharide recognition specificity and selectivity. Our results suggest that molecular imprinting approaches could be a possibility for the specific recognition of biologically active sequences in heparan sulfates., (Copyright © 2016 John Wiley & Sons, Ltd.)

There is an urgent unmet medical need for new treatments for wound and burn infections caused by multidrug-resistant Gram-negative "superbugs," especially the problematic Pseudomonas aeruginosa. In this work, the incorporation of colistin, a potent lipopeptide into a self-healable hydrogel (via dynamic imine bond formation) following the chemical reaction between the amine groups present in glycol chitosan and an aldehyde-modified poly(ethylene glycol), is reported. The storage module (G') of the colistin-loaded hydrogel ranges from 1.3 to 5.3 kPa by varying the amount of the cross-linker and colistin loading providing different options for topical wound healing. The majority of the colistin is released from the hydrogel within 24 h and remains active as demonstrated by both antibacterial in vitro disk diffusion and time-kill assays. Moreover and pleasingly, the colistin-loaded hydrogel performs almost equally well as native colistin against both the colistin-sensitive and also colistin-resistant P. aeruginosa strain in the in vivo animal "burn" infection model despite exhibiting a slower killing profile in vitro. Based on this antibiotic performance along with the biodegradability of the product, it is believed the colistin-loaded hydrogel to be a potential localized wound-healing formulation to treat burn wounds against microbial infection., (© 2016 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Salecan is a water-soluble bacterial polysaccharide consisting of glucopyranosyl units linked by α-1,3 and β-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., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report on a molecularly imprinted hydrogel for the selective fluorescent detection of a targeting protein. To achieve the fluorescent detection of proteins, a fluorescent functional monomer was synthesized with fluorescein isothiocyanate and allylamine. The monomer (FITC-AA) provided a gradable alteration of the absorption spectrum, and a decrease of the fluorescent intensity due to an interaction with the model protein, lysozyme. Also, the imprinted hydrogel (PI-gel) was simply prepared with FITC-AA, the anionic functional monomers, poly(ethylene glycol) dimethacrylate, and lysozyme by radical photo polymerization. The PI-gel showed selective adsorption for lysozyme and the imprinting factor reached to 2.7. Additionally, the PI-gel indicated a gradual decrease of the fluorescent intensity corresponding to the lysozyme concertation similar to a competitive enzyme-linked immunosorbent assay detection.

An antibacterial and biodegradable composite hydrogel dressing integrated with microspheres is developed for drug delivery and wound healing. The mechanism of gelation is attributed to the Schiff-base reaction between aldehyde and amino groups of oxidized alginate (OAlg) and carboxymethyl chitosan (CMCS). To enhance antibacterial and mechanical properties, tetracycline hydrochloride (TH) loaded gelatin microspheres (GMs) were fabricated by an emulsion cross-linking method, followed by integrating into the OAlg-CMCS hydrogel to produce a composite gel dressing. In vitro gelation time, swelling, degradation, compressive modulus and rheological properties of the gel dressing were investigated as the function of microsphere ratios. With increasing ratios of microspheres from 10 to 40mg/mL, the composite dressing manifested shorter gelation time and lower swelling ratios, as well as higher mechanical strength. Comparing to other formulations, the gel dressing with 30mg/mL microspheres showed more suitable stabilities and mechanical properties for wound healing. Also, in vitro drug release results showed that the loaded TH could be sustained release from the composite gel dressing by contrast with pure hydrogels and microspheres. Furthermore, powerful bacteria growth inhibition effects against Escherichia coli and Staphylococcus aureus suggested that the composite gel dressing, especially the one with 30mg/mL GMs containing TH, has a promising future in treatment of bacterial infection., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This paper is mainly focused on introducing cotton fabric with hydrogel and antimicrobial properties using Tragacanth gum as a natural polymer with hydrogel properties, silver nitrate as silver precursor, citric acid as a cross-linking agent and sodium hypophosphite as catalyst. The water absorption behavior of the treated fabrics was investigated with moisture regain, water retention, drying time of wetted fabric at room condition and vertical wicking tests. Antibacterial properties of the samples were evaluated against Escherichia coli and Staphylococcous aureus. The SEM pictures confirmed formation of nano silver and hydrogel layer on the fabric surface and XRD performed the crystal and particle size of the nano silver. The chemical structure of the fabric samples was identified with FTIR spectra. The central composite design (CCD) was used for statistical modelling, evaluated effective parameters and created optimum conditions. The treated cotton fabrics showed good water absorption properties along with reasonable antibacterial effectiveness., (Copyright © 2016 Elsevier Ltd. All rights reserved.)