Formation of pH-responsive hydrogel beads and their gel properties: Soybean protein nanofibers and sodium alginate

Hydrogel beads prepared from protein nanofibers are popular because of their safety, sleek appearance, and protection of biologically active substances. However, extreme external environmental variations, such as pH and temperature, can limit their practical application. To meet the application requirements of hydrogel beads in different environments, non-covalent mixtures of CaCl2 cross-linked soybean protein nanofibers (SNF) and sodium alginate (SA) were used to prepare hydrogel beads. In the present study, the hardness (782.48 g) and elasticity of hydrogel beads formed at SNF/SA = 7:3 and CaCl2 concentration of 0.1 mol/L were the maximum. Furthermore, the water content and pH swelling also reached a peak (98.68 %, 43.85 g/g) due to the best morphology and regular internal network structure. Meanwhile, the pH-responsive hydrogel beads with added anthocyanins were able to respond to the ambient pH under different temperatures and pH conditions and maintained color stability during 96 h of storage (ΔE < 5). In this experiment, a pH-responsive hydrogel bead based on soybean protein nanofiber (SNF) and sodium alginate (SA) was prepared by simple ionic crosslinking. It provides a theoretical and experimental basis for the future application of plant protein nanofibers as pH-responsive hydrogel materials.

Effect of sustained insulin-releasing device made of poly(ethylene glycol) dimethacrylates on retinal function in streptozotocin-induced diabetic rats

In this study, we developed a subcutaneous insulin-releasing device consisting of a disk-shaped capsule and drug formulation comprised of poly(ethylene glycol) dimethacrylates, then evaluated its efficacy on retinal function in streptozotocin (STZ)-induced diabetic rats. In vitro release studies showed that recombinant human insulin was released with a constant rate for more than 30 days. The device was able to maintain a basal level of blood glucose in diabetic rats for a prolonged period of more than 30 days, simultaneously preventing a decrease in body weight. For assessing the pharmacological effect of the device on retinal function in diabetic rats, electroretinograms were conducted for 12 weeks. The reduction in amplitude and delay in implicit time were attenuated by the device during the initial 4 weeks of application. The increase in gene expression of protein kinase C (PKC)-γ and caspase-3 in the diabetic retina was also attenuated by the device. Immunohistochemistry showed that the increase in glial fibrillary acidic protein expression in the diabetic retina was attenuated by the device. Histological evaluation of subcutaneous tissue around the device showed the biocompatibility of the device. In conclusion, the insulin-releasing device attenuated the reduction of retinal function in STZ-induced diabetic conditions for 4 weeks and the efficacy of the device might be partially related to PKC signaling in the retina. The long-term ability to control the blood glucose level might help to reduce the daily frequency of insulin injections.

Amino Acid-Modified Conjugated Oligomer Self-Assembly Hydrogel for Efficient Capture and Specific Killing of Antibiotic-Resistant Bacteria

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.

A Water-Soluble Microencapsulated Milk Thistle Extract as Active Ingredient for Dermal Formulations

The choice of formulation is often of crucial importance in order to obtain a pharmaceutical product for the administration of poorly soluble drugs. Recently, a new water-soluble microparticulate powder form (MTE-mp) for the oral administration of a high functionality/low solubility silymarin rich milk thistle extract (MTE) has been developed. Findings showed that extract-loaded microparticles by spray-drying were produced with high and reproducible yields and encapsulation efficiency. The in vitro dissolution and permeation rates of silymarin were dramatically improved with respect to the raw material, and also enhanced the silymarin anti-inflammatory abilities. Given these successful results, the new MTE-mp delivery system has been proposed as an active ingredient for dermal applications. The aim of this research was the design and development of two topical formulations, hydrogel and emulgel (O/W emulsion), containing the MTE-mp delivery system or MTE raw extract. All the formulations were compared to each other in terms of handling and incorporation amount of the active ingredient during the productive process. Moreover, the addition to the emulgel of lecithin (L) as enhancer of permeation was tested. The MTE-mp ingredient that resulted was stable and more-easily incorporated both in hydrogel and emulgel than raw MTE extract, obtaining the best permeation profile for MTE-mp from emulgel with the addition of L. The obtained results confirm that the MTE-mp system could be used as a stable, water-soluble, and easy-handling functional ingredient, giving the opportunity to develop new strategies for MTE delivery in health products.

Hydrogel Gate Graphene Field-Effect Transistors as Multiplexed Biosensors

Nanoscale field-effect transistors (FETs) represent a unique platform for real time, label-free transduction of biochemical signals with unprecedented sensitivity and spatiotemporal resolution, yet their translation toward practical biomedical applications remains challenging. Herein, we demonstrate the potential to overcome several key limitations of traditional FET sensors by exploiting bioactive hydrogels as the gate material. Spatially defined photopolymerization is utilized to achieve selective patterning of polyethylene glycol on top of individual graphene FET devices, through which multiple biospecific receptors can be independently encapsulated into the hydrogel gate. The hydrogel-mediated integration of penicillinase was demonstrated to effectively catalyze enzymatic reaction in the confined microenvironment, enabling real time, label-free detection of penicillin down to 0.2 mM. Multiplexed functionalization with penicillinase and acetylcholinesterase has been demonstrated to achieve highly specific sensing. In addition, the microenvironment created by the hydrogel gate has been shown to significantly reduce the nonspecific binding of nontarget molecules to graphene channels as well as preserve the encapsulated enzyme activity for at least one week, in comparison to free enzymes showing significant signal loss within one day. This general approach presents a new biointegration strategy and facilitates multiplex detection of bioanalytes on the same platform, which could underwrite new advances in healthcare research.

One-Step Nanosurface Self-Assembly of d-Peptides Renders Bubble-Free Ultrasound Theranostics

The surface bioinspired modification of particles and films is a mainstream direction in biomaterial design and application. The interfacial coating of extracellular-matrix-like hydrogel can endow functional inorganic nanoparticles high circulation stability and biocompatibility but remains challenging due to large surface tension difference between organic gelators and solid nanosurfaces. Herein, the supramolecular hydrogel of NapG_dF_dF_dK around gold nanorods (Au NRs-Gel) has been constructed by the amidation-grafting modification and the protonation-induced interface-assistant assembly of peptide precursors. As a proof of concept study, the acoustic cavitation experiments and in vitro ultrasound imaging have proved that the abundant hydrophobic microdomains as well as the water-rich network in the supramolecular hydrogel can serve as valid sites to efficiently generate and stabilize nanobubbles as cavitation seeds to realize bubble-free ultrasound imaging. In vivo augmented ultrasound imaging and imaging-guided high intensity focused ultrasound (HIFU) therapy based on the Balb/c mice bearing HeLa tumor model have been conducted. As the first example of using nanosurface hydrogelation to endow nanoparticles with bubble-free ultrasound theranostic ability, this work offers a simple approach to design multifunctional nanovehicles for ultrasound-guided drug/protein/gene delivery.

Peptide Cross-Linked Poly (Ethylene Glycol) Hydrogel Films as Biosensor Coatings for the Detection of Collagenase

Peptide cross-linked poly(ethylene glycol) hydrogel has been widely used for drug delivery and tissue engineering. However, the use of this material as a biosensor for the detection of collagenase has not been explored. Proteases play a key role in the pathology of diseases such as rheumatoid arthritis and osteoarthritis. The detection of this class of enzyme using the degradable hydrogel film format is promising as a point-of-care device for disease monitoring. In this study, a protease biosensor was developed based on the degradation of a peptide cross-linked poly(ethylene glycol) hydrogel film and demonstrated for the detection of collagenase. The hydrogel was deposited on gold-coated quartz crystals, and their degradation in the presence of collagenase was monitored using a quartz crystal microbalance (QCM). The biosensor was shown to respond to concentrations between 2 and 2000 nM in less than 10 min with a lower detection limit of 2 nM.

Novel injectable gallium-based self-setting glass-alginate hydrogel composite for cardiovascular tissue engineering

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.

Potential of Allogeneic Adipose-Derived Stem Cell-Hydrogel Complex for Treating Diabetic Foot Ulcers

Mesenchymal stem cells (MSCs) may hold great promise for treating diabetic wounds. However, it is difficult for a clinician to use MSCs because they have not been commercialized. Meanwhile, a new commercial drug that contains adipose-derived stem cells (ASCs) has been developed. The purpose of this study was to examine the potential of allogeneic ASC sheets for treating diabetic foot ulcers. Fifty-nine patients with diabetic foot ulcers were randomized to either the ASC treatment group (n = 30) or a control group treated with polyurethane film (n = 29). Either an allogeneic ASC sheet or polyurethane film was applied on diabetic wounds weekly. These wounds were evaluated for a maximum of 12 weeks. Complete wound closure was achieved for 73% in the treatment group and 47% in the control group at week 8. Complete wound closure was achieved for 82% in the treatment group and 53% in the control group at week 12. The Kaplan-Meier median times to complete closure were 28.5 and 63.0 days for the treatment group and the control group, respectively. There were no serious adverse events related to allogeneic ASC treatment. Thus, allogeneic ASCs might be effective and safe to treat diabetic foot ulcers.

Buoyancy-Driven Gradients for Biomaterial Fabrication and Tissue Engineering

The controlled fabrication of gradient materials is becoming increasingly important as the next generation of tissue engineering seeks to produce inhomogeneous constructs with physiological complexity. Current strategies for fabricating gradient materials can require highly specialized materials or equipment and cannot be generally applied to the wide range of systems used for tissue engineering. Here, the fundamental physical principle of buoyancy is exploited as a generalized approach for generating materials bearing well-defined compositional, mechanical, or biochemical gradients. Gradient formation is demonstrated across a range of different materials (e.g., polymers and hydrogels) and cargos (e.g., liposomes, nanoparticles, extracellular vesicles, macromolecules, and small molecules). As well as providing versatility, this buoyancy-driven gradient approach also offers speed (<1 min) and simplicity (a single injection) using standard laboratory apparatus. Moreover, this technique is readily applied to a major target in complex tissue engineering: the osteochondral interface. A bone morphogenetic protein 2 gradient, presented across a gelatin methacryloyl hydrogel laden with human mesenchymal stem cells, is used to locally stimulate osteogenesis and mineralization in order to produce integrated osteochondral tissue constructs. The versatility and accessibility of this fabrication platform should ensure widespread applicability and provide opportunities to generate other gradient materials or interfacial tissues.

All-Aqueous-Phase Microfluidics for Cell Encapsulation

Cell-laden hydrogel microcarriers are widely used in diverse biomedical applications like three-dimensional (3D) cell culture, cellular therapy, and tissue engineering, where microcarriers were generally produced by oil, which is the common but not optimal choice, as oil may cause cytotoxicity or protein denaturation. Here, an all-aqueous-phase microfluidics is presented to achieve oil-free emulsification of cell-laden microcapsules and 3D cell culture. Aqueous solutions with different concentration gradients are used as an immiscible continuous phase and a dispersed phase, and oscillation from a solenoid valve facilitates the formation of microcapsules at the water-water interface. By adjusting aqueous-phase flow rates and oscillating frequencies, core-shell microcapsules with controllable structures can be stably and continuously generated. In further 3D cell culture, encapsulated cells maintained good viabilities and aggregated together. These features show that the oil-free microfluidic method may have broad prospects in many biomedical applications.

In Situ Fabrication of Intelligent Photothermal Indocyanine Green-Alginate Hydrogel for Localized Tumor Ablation

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 Ca²⁺/Mg²⁺ stimuli-responsive ICG-alginate hydrogel in vivo for localized tumor photothermal therapy. An ICG-alginate hydrogel can form by the simple introduction of Ca²⁺/Mg²⁺ 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.

Investigations of Anti-Inflammatory Activity of a Peptide-Based Hydrogel Using Rat Air Pouch Model

The growing area of biomaterial sciences has attracted broad attention in recent years in the development of peptide-based biocompatible materials with inherent therapeutic potentials. Here, we developed an Amoc (9-anthracenemethoxycarbonyl)-capped dipeptide-based biocompatible, injectable, thixotropic, and self-healable hydrogel. In vitro cytotoxicity of the hydrogel was investigated with the human embryonic kidney cell (HEK293) line. We observed that the synthesized peptide is noncytotoxic. The hydrogel showed an antibacterial efficacy against Gram-positive and Gram-negative bacteria. In vivo anti-inflammatory activity of the hydrogel was investigated using the rat air pouch model of acute inflammation. The major parameters considered for the anti-inflammatory study were exudate volume, total and differential white blood cell count, tissue histology, and lipid peroxidation assay. These experimental data suggest biocompatibility and potential therapeutic applications of peptide hydrogel in inflammation.

Black Phosphorus Hydrogel Scaffolds Enhance Bone Regeneration via a Sustained Supply of Calcium-Free Phosphorus

Effective bone regeneration remains a challenge for bone-tissue engineering. In this study, we propose a new strategy to accelerate bone regeneration via a sustained supply of phosphorus without providing foreign calcium. Herein, a black phosphorus nanosheet (BPN)-based hydrogel platform was developed, and the BPNs were used to stably and mildly provide phosphorus. The hydrogel was fabricated by photo-crosslinking of gelatin methacrylamide, BPNs, and cationic arginine-based unsaturated poly(ester amide)s. This platform combines the following advantages: the hydrogel scaffold would keep BPNs inside, and the encapsulated BPNs can degrade into phosphorus ions and capture calcium ions to accelerate biomineralization in a bone defect. The introduction of BPNs helped to enhance the mechanical performance of hydrogels, photoresponsively release phosphate, and accelerate mineralization in vitro. Moreover, BPN-containing hydrogels improved osteogenic differentiation of human dental pulp stem cells via the bone morphogenic protein-runt-related transcription factor 2 pathway. In vivo results from a rabbit model of bone defects revealed that the BPNs helped to accelerate bone regeneration. All these results strongly suggest that the strategy of a sustained supply of calcium-free phosphorus and this BPN-containing hydrogel platform hold promise for effective bone regeneration.

Bifurcation-based embodied logic and autonomous actuation

Many plants autonomously change morphology and function in response to environmental stimuli or sequences of stimuli. In contrast with the electronically-integrated sensors, actuators, and microprocessors in traditional mechatronic systems, natural systems embody these sensing, actuation, and control functions within their compositional and structural features. Inspired by nature, we embody logic in autonomous systems to enable them to respond to multiple stimuli. Using 3D printable fibrous composites, we fabricate structures with geometries near bifurcation points associated with a transition between bistability and monostability. When suitable stimuli are present, the materials swell anisotropically. This forces a key geometric parameter to pass through a bifurcation, triggering rapid and large-amplitude self-actuation. The actuation time can be programmed by varying structural parameters (from 0.6 to 108 s for millimeter-scale structures). We demonstrate this bioinspired control strategy with examples that respond to their environment according to their embodied logic, without electronics, external control, or tethering.

Microfluidic formation of core-shell alginate microparticles for protein encapsulation and controlled release

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.

Accelerate Healing of Severe Burn Wounds by Mouse Bone Marrow Mesenchymal Stem Cell-Seeded Biodegradable Hydrogel Scaffold Synthesized from Arginine-Based Poly(ester amide) and Chitosan

Severe burns are some of the most challenging problems in clinics and still lack ideal modalities. Mesenchymal stem cells (MSCs) incorporated with biomaterial coverage of burn wounds may offer a viable solution. In this report, we seeded MSCs to a biodegradable hybrid hydrogel, namely ACgel, that was synthesized from unsaturated arginine-based poly(ester amide) (UArg-PEA) and chitosan derivative. MSC adhered to ACgels. ACgels maintained a high viability of MSCs in culture for 6 days. MSC seeded to ACgels presented well in third-degree burn wounds of mice at 8 days postburn (dpb) after the necrotic full-thickness skin of burn wounds was debrided and filled and covered by MSC-carrying ACgels. MSC-seeded ACgels promoted the closure, reepithelialization, granulation tissue formation, and vascularization of the burn wounds. ACgels alone can also promote vascularization but less effectively compared with MSC-seeded ACgels. The actions of MSC-seeded ACgels or ACgels alone involve the induction of reparative, anti-inflammatory interleukin-10, and M2-like macrophages, as well as the reduction of inflammatory cytokine TNFα and M1-like macrophages at the late inflammatory phase of burn wound healing, which provided the mechanistic insights associated with inflammation and macrophages in burn wounds. For the studied regimens of these treatments, no toxicity was identified to MSCs or mice. Our results indicate that MSC-seeded ACgels have potential use as a novel adjuvant therapy for severe burns to complement commonly used skin grafting and, thus, minimize the downsides of grafting.

Coaxially-structured fibres with tailored material properties for vascular graft implant

Readily-available small-diameter arterial grafts require a great combination of materials properties, including high strength, compliance, suturability, blood sealing and anti-thrombogenicity, as well as anti-kinking property for those used in challenging anatomical situations. We have constructed grafts composed of coaxially-structured polycaprolactone (PCL)/gelatin nanofibres, and tailored the material structures to achieve high strength, compliance and kink resistance, as well as excellent water sealing and anti-thrombogenicity. Coaxially-structured fibres in the grafts provided mechanical stability through the core, while flexibility and cell adhesion through the sheath. Results showed that graft compliance increased while strength decreased with the concentration ratio between core and sheath polymers. Compared to pure PCL fibrous surfaces, coaxial PCL/gelatin fibrous surfaces potently inhibited platelet adhesion and activation, providing excellent anti-thrombogenicity. To render sufficient burst strength and suturability, an additional layer of pure PCL was necessary to cap the layer of coaxial PCL/gelatin fibres. The two-layered grafts with the wall thickness comparable to native arteries demonstrated artery-like compliance and kink resistance, properties important to arteries under complex mechanical loading. The in vivo evaluation was performed using the interposition carotid artery graft model in rabbits for three months. Interestingly, results from ultrasonic imaging and histological analysis demonstrated that the two-layered grafts with a thinner outer PCL layer, which possessed higher compliance and kink resistance, showed increased blood flow, minimal lumen reduction and fibrosis. All vascular grafts exhibited patency and induced limited cell infiltration. Together, we presented a facile and useful approach to fabricate vascular grafts with superior graft performances, biomechanical properties, and blood compatibility. Grafts with artery-like compliance and flexibility have demonstrated improved implantation outcomes.

Research progress of self-assembled nanogel and hybrid hydrogel systems based on pullulan derivatives

Polymer nano-sized hydrogels (nanogels) as drug delivery carriers have been investigated over the last few decades. Pullulan, a nontoxic and nonimmunogenic hydrophilic polysaccharide derived from fermentation of black yeast like Aureobasidium pullulans with great biocompatibility and biodegradability, is one of the most attractive carriers for drug delivery systems. In this review, we describe the preparation, characterization, and 'switch-on/off' mechanism of typical pullulan self-assembled nanogels (self-nanogels), and then introduce the development of hybrid hydrogels that are numerous resources applied for regenerative medicine. A major section is used for biomedical applications of different nanogel systems based on modified pullulan, which exert smart stimuli-responses at ambient conditions such as charge, pH, temperature, light, and redox. Pullulan self-nanogels have found increasingly extensive application in protein delivery, tissue engineering, vaccine development, cancer therapy, and biological imaging. Functional groups are incorporated into self-nanogels and contribute to expressing desirable results such as targeting and modified release. Various molecules, especially insoluble or unstable drugs and encapsulated proteins, present improved solubility and bioavailability as well as reduced side effects when incorporated into self-nanogels. Finally, the advantages and disadvantages of pullulan self-nanogels will be analyzed accordingly, and the development of pullulan nanogel systems will be reviewed.

Enzymatically Disulfide-Crosslinked Chitosan/Hyaluronic Acid Layer-by-Layer Self-Assembled Microcapsules for Redox-Responsive Controlled Release of Protein

Disulfide-crosslinked hollow polyelectrolyte microcapsules composed of thiolated chitosan (CS-SH) and hyaluronic acid (HA-SH) were prepared by combining the layer-by-layer (LBL) technique and horseradish peroxidase (HRP)-mediated oxidative cross-linking reaction in mild conditions. FITC-dextran-doped CaCO₃ microspheres were used as template core and removed after LBL depositing CS-SH and HA-SH on the surface. The disulfide-crosslinked (CS/HA) microcapsules were readily fabricated by HRP-mediated oxidative coupling of the thiol groups in CS/HA shell layer in the presence of HRP (10 units/mL) and Tyramine hydrochloride (Tyr, 35 mmol/L). The kinetics of enzymatic disulfide-crosslinking reaction was investigated through the real-time monitoring of the consumption of thiol groups by UV absorption spectra. It found that the formation of disulfide linkages by the enzymatic thiol oxidation reaction showed a gradual acceleration. The disulfide-crosslinked CS/HA hydrogel were rapidly formed in gelation time between approximately 17 and 30 min, which were dependent on the concentrations of HRP and Tyr. The disulfide linkages endowed the microcapsule-enhanced physical stability and low permeability under physiological conditions and redox-responsive degradability in reducing environments. The structural stability of disulfide-crosslinked (CS/HA) microcapsules was visualized by confocal laser scanning microscopy in phosphate-buffered saline containing 5.0 mmol/L dithiothreitol (DTT) to evaluate the redox-responsive disassembly process. Redox-responsive controlled release of encapsulated FITC-dextran from the disulfide-crosslinked (CS/HA) microcapsules were obtained. The release profiles of FITC-dextran could be manipulated by controlling the shell thickness and the concentration of DTT. The conformational stability analyses and more than 94% esterase activity of released bovine serum albumin (BSA) from (CS/HA) microcapsules conformed that the structural integrity and bioactivity were well preserved during the encapsulation and release process. The microcapsules exhibited excellent cytocompatibility for HEK 293 cells up to a concentration of 1.0 mg/mL. The microcapsules efficiently delivered loaded FITC-BSA into HeLa cells and released the protein in the reducing cytosol. This study proposed a novel approach for producing disulfide-crosslinked microcarriers for intracellular delivery and redox-responsive controlled release of protein.

Biocompatible Coatings from Smart Biopolymer Nanoparticles for Enzymatically Induced Drug Release

Nanoparticles can be used as a smart drug delivery system, when they release the drug only upon degradation by specific enzymes. A method to create such responsive materials is the formation of hydrogel nanoparticles, which have enzymatically degradable crosslinkers. Such hydrogel nanoparticles were prepared by ionotropic gelation sodium alginate with lysine-rich peptide sequences-either α-poly-L-lysine (PLL) or the aggrecanase-labile sequence KKKK-GRD-ARGSV↓NITEGE-DRG-KKKK. The nanoparticle suspensions obtained were analyzed by means of dynamic light scattering and nanoparticle tracking analysis. Degradation experiments carried out with the nanoparticles in suspension revealed enzyme-induced lability. Drugs present in the polymer solution during the ionotropic gelation can be encapsulated in the nanoparticles. Drug loading was investigated for interferon-β (IFN-β) as a model, using a bioluminescence assay with MX2Luc2 cells. The encapsulation efficiency for IFN-β was found to be approximately 25%. The nanoparticles suspension can be used to spray-coat titanium alloys (Ti-6Al-4V) as a common implant material. The coatings were proven by ellipsometry, reflection-absorption infrared spectroscopy, and X-ray photoelectron spectroscopy. An enzyme-responsive decrease in layer thickness is observed due to the degradation of the coatings. The Alg/peptide coatings were cytocompatible for human gingival fibroblasts (HGFIB), which was investigated by CellTiterBlue and lactate dehydrogenase (LDH) assay. However, HGFIBs showed poor adhesion and proliferation on the Alg/peptide coatings, but these could be improved by modification of the alginate with a RGD-peptide sequence. The smart drug release system presented can be further tailored to have the right release kinetics and cell adhesion properties.

From individual to collective 3D cancer dissemination: roles of collagen concentration and TGF-β

Cancer cells have the ability to migrate from the primary (original) site to other places in the body. The extracellular matrix affects cancer cell migratory capacity and has been correlated with tissue-specific spreading patterns. However, how the matrix orchestrates these behaviors remains unclear. Here, we investigated how both higher collagen concentrations and TGF-β regulate the formation of H1299 cell (a non-small cell lung cancer cell line) spheroids within 3D collagen-based matrices and promote cancer cell invasive capacity. We show that at low collagen concentrations, tumor cells move individually and have moderate invasive capacity, whereas when the collagen concentration is increased, the formation of cell clusters is promoted. In addition, when the concentration of TGF-β in the microenvironment is lower, most of the clusters are aggregates of cancer cells with a spheroid-like morphology and poor migratory capacity. In contrast, higher concentrations of TGF-β induced the formation of clusters with a notably higher invasive capacity, resulting in clear strand-like collective cell migration. Our results show that the concentration of the extracellular matrix is a key regulator of the formation of tumor clusters that affects their development and growth. In addition, chemical factors create a microenvironment that promotes the transformation of idle tumor clusters into very active, invasive tumor structures. These results collectively demonstrate the relevant regulatory role of the mechano-chemical microenvironment in leading the preferential metastasis of tumor cells to specific tissues with high collagen concentrations and TFG-β activity.

Intra-Articular Formulation of GE11-PLGA Conjugate-Based NPs for Dexamethasone Selective Targeting-In Vitro Evaluation

Selectively targeted nanoscale drug delivery systems have recently emerged as promising intravenously therapeutic option for most chronic joint diseases. Here, a newly synthetized dodecapeptide (GE11)-polylactide-co-glycolide (PLGA)-based conjugate was used to prepare smart nanoparticles (NPs) intended for intra-articular administration and for selectively targeting Epidermal Growth Factor Receptor (EGFR). GE11-PLGA conjugate-based NPs are specifically uptaken by EGFR-overexpressed fibroblast; such as synoviocytes; which are the primarily cellular component involved in the development of destructive joint inflammation. The selective uptake could help to tune drug effectiveness in joints and to decrease local and systemic side effects. Dexamethasone (DXM) is a glucorticoid drug commonly used in joint disease treatment for both systemic and local administration route. In the present research; DXM was efficiently loaded into GE11-PLGA conjugate-based NPs through an eco-friendly nanoprecipitation method set up for this purpose. DXM loaded GE11-PLGA conjugate-based NPs revealed satisfactory ex vivo cytocompatibility; with proper size (≤150 nm) and good dimensional stability in synovial fluid. Intra-articular formulation was developed embedding DXM loaded GE11-PLGA conjugate-based NPs into thermosetting chitosan-based hydrogel; forming a biocompatible composite hydrogel able to quickly turn from liquid state into gel state at physiological temperature; within 15 min. Moreover; the use of thermosetting chitosan-based hydrogel extends the local release of active agent; DXM.

BioBits™ Explorer: A modular synthetic biology education kit

Hands-on demonstrations greatly enhance the teaching of science, technology, engineering, and mathematics (STEM) concepts and foster engagement and exploration in the sciences. While numerous chemistry and physics classroom demonstrations exist, few biology demonstrations are practical and accessible due to the challenges and concerns of growing living cells in classrooms. We introduce BioBits™ Explorer, a synthetic biology educational kit based on shelf-stable, freeze-dried, cell-free (FD-CF) reactions, which are activated by simply adding water. The FD-CF reactions engage the senses of sight, smell, and touch with outputs that produce fluorescence, fragrances, and hydrogels, respectively. We introduce components that can teach tunable protein expression, enzymatic reactions, biomaterial formation, and biosensors using RNA switches, some of which represent original FD-CF outputs that expand the toolbox of cell-free synthetic biology. The BioBits™ Explorer kit enables hands-on demonstrations of cutting-edge science that are inexpensive and easy to use, circumventing many current barriers for implementing exploratory biology experiments in classrooms.

Protein-Based Electronic Skin Akin to Biological Tissues

Human skin provides an interface that transduces external stimuli into electrical signals for communication with the brain. There has been considerable effort to produce soft, flexible, and stretchable electronic skin (E-skin) devices. However, common polymers cannot imitate human skin perfectly due to their poor biocompatibility, biofunctionality, and permeability to many chemicals and biomolecules. Herein, we report on highly flexible, stretchable, conformal, molecule-permeable, and skin-adhering E-skins that combine a metallic nanowire (NW) network and silk protein hydrogel. The silk protein hydrogels offer high stretchability and stability under hydration through the addition of Ca²⁺ ions and glycerol. The NW electrodes exhibit stable operation when subjected to large deformations and hydration. Meanwhile, the hydrogel window provides water and biomolecules to the electrodes (communication between the environment and the electrode). These favorable characteristics allow the E-skin to be capable of sensing strain, electrochemical, and electrophysiological signals.

Water- and Fertilizer-Integrated Hydrogel Derived from the Polymerization of Acrylic Acid and Urea as a Slow-Release N Fertilizer and Water Retention in Agriculture

To reduce the preparation cost of superabsorbent and improve the N release rate at the same time, a novel low-cost superabsorbent (SA) with the function of N slow release was prepared by chemical synthesis with neutralized acrylic acid (AA), urea, potassium persulfate (KPS), and N, N'-methylenebis(acrylamide) (MBA). The order of influence factors on the water absorbency property was determined by an orthogonal L₁₈(3)⁷ experiment. On the basis of the optimization results of the orthogonal experiment, the effects of a single factor on the water absorption were investigated, and the highest water absorbency (909 g/g) was achieved for the conditions of 1.0 mol urea/mol AA ratio, 100% of AA neutralized, K⁺, 1.5% KPS to AA mass fraction, 0.02% MBA to AA mass fraction, 45 °C reaction temperature, and 4.0 h reaction time. The optimal sample was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Swelling behaviors of the superabsorbent were investigated in distilled water and various soil and salt solutions. The water-release kinetics of SA in different negative pressures and soils were systematically investigated. Additionally, the maize seed germination in various types of soil with different amounts of SA was proposed, and the N could release 3.71% after being incubated in distilled water for 40 days. After 192 h, the relative water content of SA-treated sandy loam, loam, and paddy soil were 42, 56, and 45%, respectively. All of the results in this work showed that SA had good water retention and slow N-release properties, which are expected to have potential applications in sustainable modern agriculture.

Sodium alginate/graphene oxide hydrogel beads as permeable reactive barrier material for the remediation of ciprofloxacin-contaminated groundwater

The wide occurrence of antibiotics in groundwater has raised serious concerns due to their impacts on humans and the ecosystem. Most of the research in groundwater remediation focuses on the exploitation of nano-materials. However, nano-materials have several disadvantages such as high production cost, rapid reduction in permeability, disposal problems, and high sensitivity to environmental conditions. To solve these issues, novel sodium alginate/graphene oxide hydrogel beads (GSA) were synthesised and their effectiveness as permeable reactive barrier (PRB) backfill material in the remediation of ciprofloxacin (CPX)-contaminated groundwater was tested. The adsorption of CPX onto GSA followed the pseudo-second-order kinetic model. The isotherm data followed the Freundlich model. The maximum adsorption capacity was 100 mg g^-1 at pH 7.0. The adsorption process was sensitive to contact time, initial CPX concentration and ionic strength. However, it was not pH sensitive. Hydrophobic interaction, electrostatic interaction, ion exchange, H-bonding, and pore filling were proposed to be the main adsorption mechanisms. The effects of flow rate, influent CPX concentration, and ionic strength on the performance of PRB were confirmed through flow-through column experiments and by using a chemical non-equilibrium two-site model. Accordingly, a proper PRB was designed based on hydrogeological conditions. Finally, the lifetime and cost of the PRBs were calculated. The results obtained provided concrete evidence that GSA is a promising adsorbent material for PRBs applications in the remediation of CPX-contaminated groundwater.

Pericardial application as a new route for implanting stem-cell cardiospheres to treat myocardial infarction

KEY POINTS

Cardiospheres (CSps) are a promising new form of cardiac stem cells with advantage over other stem cells for myocardial regeneration, but direct implantation of CSps by conventional routes has been limited due to potential embolism. We have implanted CSps into the pericardial cavity and systematically demonstrated its efficacy regarding myocardial infarction. Stem cell potency and cell viability can be optimized in vitro prior to implantation by pre-conditioning CSps with pericardial fluid and hydrogel packing. Transplantation of optimized CSps into the pericardial cavity improved cardiac function and alleviated myocardial fibrosis, increased myocardial cell survival and promoted angiogenesis. Mechanistically, CSps are able to directly differentiate into cardiomyocytes in vivo and promote regeneration of myocardial cells and blood vessels through a paracrine effect with released growth factors as potential paracrine mediators. These findings establish a new strategy for therapeutic myocardial regeneration to treat myocardial infarction.

ABSTRACT

Cardiospheres (CSps) are a new form of cardiac stem cells with an advantage over other stem cells for myocardial regeneration. However, direct implantation of CSps by conventional routes to treat myocardial infarction has been limited due to potential embolism. We have implanted CSps into the pericardial cavity and systematically assessed its efficacy on myocardial infarction. Preconditioning with pericardial fluid enhanced the activity of CSps and matrix hydrogel prolonged their viability. This shows that pretransplant optimization of stem cell potency and maintenance of cell viability can be achieved with CSps. Transplantation of optimized CSps into the pericardial cavity improved cardiac function and alleviated myocardial fibrosis in the non-infarcted area, and increased myocardial cell survival and promoted angiogenesis in the infarcted area. Mechanistically, CSps were able to directly differentiate into cardiomyocytes in vivo and promoted regeneration of myocardial cells and blood vessels in the infarcted area through a paracrine effect with released growth factors in pericardial cavity serving as possible paracrine mediators. This is the first demonstration of direct pericardial administration of pre-optimized CSps, and its effectiveness on myocardial infarction by functional and morphological outcomes with distinct mechanisms. These findings establish a new strategy for therapeutic myocardial regeneration to treat myocardial infarction.

Thermosensitive Injectable Hydrogel for Simultaneous Intraperitoneal Delivery of Doxorubicin and Prevention of Peritoneal Adhesion

To improve intraperitoneal chemotherapy and to prevent postsurgical peritoneal adhesion, we aimed to develop a drug delivery strategy for controlled release of a chemotherapeutic drug from the intraperitoneally injected thermosensitive poly(N-isopropylacrylamide)-based hydrogel (HACPN), which is also endowed with peritoneal anti-adhesion properties. Anticancer drug doxorubicin (DOX) was loaded into the hydrogel (HACPN-DOX) to investigate the chemotherapeutic and adhesion barrier effects in vivo. A burst release followed by sustained release of DOX from HACPN-DOX was found due to gradual degradation of the hydrogel. Cell culture studies demonstrated the cytotoxicity of released DOX toward CT-26 mouse colon carcinoma cells in vitro. Using peritoneal carcinomatosis animal model in BALB/c mice with intraperitoneally injected CT-26 cells, animals treated with HACPN-DOX revealed the best antitumor efficacy judging from tumor weight and volume, survival rate, and bioluminescence signal intensity when compared with treatment with free DOX at the same drug dosage. HACPN (or HACPN-DOX) also significantly reduced the risk of postoperative peritoneal adhesion, which was generated by sidewall defect-cecum abrasion in tumor-bearing BALB/c mice, from gross and histology analyses. This study could create a paradigm to combine controlled drug release with barrier function in a single drug-loaded injectable hydrogel to enhance the intraperitoneal chemotherapeutic efficacy while simultaneously preventing postsurgical adhesion.

Preparation and characterisation of a novel hydrogel based on Auricularia polytricha β-glucan and its bio-release property for vitamin B12 delivery

BACKGROUND

This study investigates a novel hydrogel synthesis method and its bio-release property. This hydrogel, with a three-dimensional network structure based on Auricularia polytricha β-glucan, was characterised by means of Fourier transform infrared spectroscopy, ¹ H NMR and scanning electron microscopy. Vitamin B₁₂ (VB₁₂ , cobalamin) as a hydrophilic functional food component was entrapped into these hydrogels. The in vitro release profile of VB₁₂ was established in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF).

RESULTS

The results showed that the hydrogel had medium pore size from 30 to 300 µm, and the swelling ratio increased with the degree of substitution. The hydrogel demonstrated good stability in SGF and bio-release capability in SIF for VB₁₂ . The accumulated release rate is about 80% in SIF and below 20% in SGF, which indicated the significant different release property in stomach and intestine.

CONCLUSION

The Auricularia polytricha β-glucan-based hydrogel has a good swelling ratio, pepsin stability and pancrelipase-catalysed biodegradation property. The bio-release rate is significantly different in SIF and SGF, which indicated that this hydrogel could be a good intestinal target carrier of VB₁₂ . © 2017 Society of Chemical Industry.

Clinical Application of Bone Morphogenetic Protein-2 Microcarriers Fabricated by the Cryopolymerization of Gelatin Methacrylate for the Treatment of Radial Fracture in Two Dogs

Bone morphogenetic protein-2 (BMP-2) effectively induces bone healing. However, the efficacy of BMP-2 relies heavily on its delivery vehicle because of its short half-life. We utilized a microcarrier fabricated by the cryopolymerization of gelatin methacrylate (cryoGelMA) infused with bone morphogenetic protein-2 (cryoGelMA-BMP-2) for the sustained and localized release of growth factors. Two dogs with radius and ulnar fractures were treated with implanted cryoGelMA-BMP-2 to accelerate bone healing. The cases were followed up for 6 months and 2 months after surgery, respectively. Distinctive healing processes were observed. The operated limb regained its premorbid function, the fracture line disappeared, and the gait was functionally stable. Implantation of cryoGelMA-BMP-2 resulted in the successful healing of bone fractures.

Tumor Ablation and Therapeutic Immunity Induction by an Injectable Peptide Hydrogel

Immunosuppressive tumor microenvironments (TMEs) create tremendous obstacles for an effective cancer therapy. Herein, we developed a melittin-RADA₃₂ hybrid peptide hydrogel loaded with doxorubicin (DOX) for a potent chemoimmunotherapy against melanoma through the active regulation of TMEs. The formed melittin-RADA₃₂-DOX (MRD) hydrogel has an interweaving nanofiber structure and exhibits excellent biocompatibility, controlled drug release properties both in vitro and in vivo, and an enhanced killing effect to melanoma cells. A single-dose injection of MRD hydrogel retarded the growth of primary melanoma tumors by more than 95% due to loaded melittin and DOX, with concomitant recruitment of activated natural killer cells in the tumors. Furthermore, MRD hydrogel can activate dendritic cells of draining lymph nodes, specifically deplete M2-like tumor-associated macrophages (TAMs), and produce active, cytotoxic T cells to further defend the cells against remaining tumors, providing potent anticancer efficacy against subcutaneous and metastatic tumors in vivo. Multidose injection of MRD hydrogel eliminated 50% of the primary tumors and provided a strong immunological memory effect against tumor rechallenge after eradication of the initial tumors. Owing to its abilities to perform controlled drug release, regulate innate immune cells, deplete M2-like TAMs, direct anticancer and immune-stimulating capabilities, and reshape immunosuppressive TMEs, MRD hydrogel may serve as a powerful tool for anticancer applications.

Macromolecule-Network Electrostatics Controlling Delivery of the Biotherapeutic Cell Modulator TIMP-2

Tissue inhibitor of metalloproteinase 2 (TIMP-2) is an endogenous 22 kDa proteinase inhibitor, demonstrating antitumorigenic, antimetastatic and antiangiogenic activities in vitro and in vivo. Recombinant TIMP-2 is currently undergoing preclinical testing in multiple, murine tumor models. Here we report the development of an inert, injectable peptide hydrogel matrix enabling encapsulation and sustained release of TIMP-2. We studied the TIMP-2 release profile from four β-hairpin peptide gels of varying net electrostatic charge. A negatively charged peptide gel (designated AcVES3) enabling encapsulation of 4 mg/mL of TIMP-2, without effects on rheological properties, facilitated the slow sustained release (0.9%/d) of TIMP-2 over 28 d. Released TIMP-2 is structurally intact and maintains the ability to inhibit MMP activity, as well as suppress lung cancer cell proliferation in vitro. These findings suggest that the AcVES3 hydrogel will be useful as an injectable vehicle for systemic delivery of TIMP-2 in vivo for ongoing preclinical development.

A Novel Anisotropic Hydrogel with Integrated Self-Deformation and Controllable Shape Memory Effect

Although shape memory polymers have been highlighted widely and developed rapidly, it is still a challenging task to realize complex temporary shapes automatically in practical applications. Herein, a novel shape memory hydrogel with the ability of self-deformation is presented. Through constructing an anisotropic poly(acrylic acid)-polyacrylamide (PAAc-PAAm) structure, the obtained hydrogel exhibits stable self-deformation behavior in response to pH stimulus, and the shapes that formed automatically can be fixed by the coordination between carboxylic groups and Fe³⁺ ; therefore, self-deformation and shape memory behaviors are integrated in one system. Moreover, the magnitude of auto-deformation and shape memory could be adjusted with the concentration of corresponding ions, leading to programmable shape memory and shape recovery processes.

Spectroscopic studies of the silicone oil impact on the ophthalmic hydrogel based materials conducted in time dependent mode

Silicone oil is the one of the artificial materials used in vitreoretinal surgery for retinal detachment treatment. Since the silicone oil is sometimes applied along with intraocular lens (IOL) implantation the direct influence of silicone oil on the artificial implant should be taken into account. Presented study was performed in order to determine the time-dependent impact of silicone oil on hydrogel based ophthalmic materials. Two kinds of IOLs based on hydroxyethyl 2-methacrylate (HEMA) hydrogel material were immersed in silicone oil based on linear poly(dimethylsiloxane) (PDMS). Incubation in oil medium was performed in 37°C for 1, 3 and 6months. After appropriate period of the incubation samples were examined by means of FTIR-ATR method as the technique of surface study as well as Positron Annihilation Lifetime Spectroscopy (PALS) as the method of internal structure investigation. Results obtained during the study revealed that silicone oil is not capable to penetrate the internal structure of investigated materials and its impact has come down to interaction with the samples surfaces only.

An Injectable, Dual Responsive, and Self-Healing Hydrogel Based on Oxidized Sodium Alginate and Hydrazide-Modified Poly(ethyleneglycol)

Oxidized sodium alginate is a handily modifiable polysaccharide owing to the pendant aldehyde groups which can form dynamic covalent bonds with amines, acylhydrazines, etc., providing oxidized sodium alginate-based hydrogels with stimuli-responsive properties. However, due to the stiffness and, in particular, the hydrophobicity of sodium alginate dialdehyde at low pH, the mechanical performance and pH stimuli responsiveness of oxidized sodium alginate-based hydrogels are still strictly limited. Herein, we report a new strategy to build an injectable, dual responsive, and self-healing hydrogel based on oxidized sodium alginate and hydrazide-modified poly(ethyleneglycol) (PEG). The hydrazide-modified PEG, referred to as PEG-DTP, acts as a macromolecule crosslinker. We found that the presence of PEG-DTP reduces the hydrophobicity of oxidized sodium alginate at low pH so effectively that even a pH-induced reversible sol-gel transitions can be realized. Meanwhile, the disulfide bonds in PEG-DTP endows the hydrogel with the other reversible sol-gel transitions by redox stimuli. In particular, due to the softness of PEG-DTP chains, mechanical performance was also enhanced significantly. Our results indicate we can easily integrate multi-stimuli responsiveness, injectability, and self-healing behavior together into an oxidized sodium alginate-based hydrogel merely by mixing an oxidized sodium alginate solution with PEG-DTP solution in certain proportions.

Kinetic research on dechlorinating dichlorobenzene in aqueous system by nano-scale nickel/iron loaded with CMC/NFC hydrogel

In this study, we reported on the nano-scale nickel/iron particles loaded in carboxymethyl/nanofibrillated cellulose (CMC/NFC) hydrogel for the dechlorination of o-dichlorobenzene (DCB) in aqueous solution. The biodegradable hydrogel may provide an ideal supporting material for fastening the bimetallic nano-scale particles, which was examined and characterized by TEM, SEM-EDX, FT-IR and BET. The performance of the selected bimetallic particles was evaluated by conducting the dechlorination of DCB in the solution under different reaction conditions (e.g., pH, dosage of nickel/iron nanoparticles and temperature). The results showed that about 70% of DCB could be dechlorinated at 20 °C in 8 h, which indicated that the immobilized reactive material had a high reduction activity when Ni/Fe loading dosage in the hydrogel (18 wt%) was considered. Moreover, the reduction behavior agreed to the pseudo-first order reaction, in which the dechlorination rate was irrelative to the pH aqueous solution. A kinetic model for predicting the concentration of DCB during the reduction reaction was established based on the experimental data.

Assessment of Chitosan-Based Hydrogel and Photodynamic Inactivation against Propionibacterium acnes

Chitosan (CH) is a biopolymer that exhibits a number of interesting properties such as anti-inflammatory and antibacterial activity and is also a promising platform for the incorporation of photosensitizing agents. This study aimed to evaluate the efficacy of antimicrobial activity of chitosan hydrogel formulation alone and in combination with the methylene blue (MB) associated with antimicrobial photodynamic therapy (aPDT) against planktonic and biofilm phase of Propionibacterium acnes. Suspensions were sensitized with 12.5, 25.0, 37.5, 50.0 μg/mL of MB for 10 min and biofilms to 75, 100 and 150 μg/mL for 30 min then exposed to red light (660 nm) at 90 J/cm² and 150 J/cm² respectively. After treatments, survival fractions were calculated by counting the number of colony-forming units. The lethal effect of aPDT associated with CH hydrogel in planktonic phase was achieved with 12.5 µg/mL MB and 1.9 log10 biofilm reduction using 75 µg/mL MB. Rheological studies showed that formulations exhibited pseudoplastic non-Newtonian behavior without thixotropy. Bioadhesion test evidenced that the formulations are highly adhesive to skin and the incorporation of MB did not influence the bioadhesive force of the formulations.

Influence of Drug-Carrier Polymers on Alpha-Synucleinopathies: A Neglected Aspect in New Therapies Development

Current therapeutic strategies to treat neurodegenerative diseases, such as alpha-synucleinopathies, aim at enhancing the amount of drug reaching the brain. Methods proposed, such as intranasal administration, should be able to bypass the blood brain barrier (BBB) and even when directly intracerebrally injected they could require a carrier to enhance local release of drugs. We have investigated the effect of a model synthetic hydrogel to be used as drug carrier on the amount of alpha-synuclein aggregates in cells in culture. The results indicated that alpha-synuclein aggregation was affected by the synthetic polymer, suggesting the need for testing the effect of any used material on the pathological process before its application as drug carrier.

Polymerization-Induced Phase Separation Formation of Structured Hydrogel Particles via Microfluidics for Scar Therapeutics

Excessive scar formation can form disabling contractures that result in a debilitating psychological outcome. Sustainable hydrophobic corticosteroid release in vivo is essential to regulate the wound healing process. Functional hydrogel particles are widely applied for sustainable release. However, due to the limited aqueous solubility of hydrophobic compounds, most of the corticosteroid is released from the hydrogels within seconds, causing undesirable scar formation and recurrence. In this study, a novel polymerization-induced phase separation is investigated to form well-defined polyethylene glycol diacrylate (PEGDA) core/alginate shell structured hydrogel particles using microfluidics without toxic organic solvents. Based on their wettability preference, hydrophobic corticosteroid-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles are compartmentalized in the PEGDA core during polymerization to control the corticosteroid release. The distribution of the PLGA nanoparticles is precisely regulated by the phase separation boundary and characterized using a fluorescent dye. The thickness of the shell and partition coefficients are determined using the UV intensity and irradiation period. Upon encapsulation of the PLGA nanoparticles within the poly(PEGDA) core, a long-term corticosteroid treatment is developed and effective scar therapeutic outcomes are evaluated using both in vitro and in vivo models.

PEG hydrogel containing calcium-releasing particles and mesenchymal stromal cells promote vessel maturation

The use of human mesenchymal stromal cells (hMSC) for treating diseased tissues with poor vascularization has received significant attention, but low cell survival has hampered its translation to the clinic. Bioglasses and glass-ceramics have also been suggested as therapeutic agents for stimulating angiogenesis in soft tissues, but these effects need further evaluation in vivo. In this study, calcium-releasing particles and hMSC were combined within a hydrogel to examine their vasculogenic potential in vitro and in vivo. The particles provided sustained calcium release and showed proangiogenic stimulation in a chorioallantoic membrane (CAM) assay. The number of hMSC encapsulated in a degradable RGD-functionalized PEG hydrogel containing particles remained constant over time and IGF-1 release was increased. When implanted in the epidydimal fat pad of immunocompromised mice, this composite material improved cell survival and stimulated vessel formation and maturation. Thus, the combination of hMSC and calcium-releasing glass-ceramics represents a new strategy to achieve vessel stabilization, a key factor in the revascularization of ischemic tissues.

STATEMENT OF SIGNIFICANCE

Increasing blood vessel formation in diseased tissues with poor vascularization is a current clinical challenge. Cell therapy using human mesenchymal stem cells has received considerable interest, but low cell survival has hampered its translation to the clinic. Bioglasses and glass-ceramics have been explored as therapeutic agents for stimulating angiogenesis in soft tissues, but these effects need further evaluation in vivo. By incorporating both human mesenchymal stem cells and glass-ceramic particles in an implantable hydrogel, this study provides insights into the vasculogenic potential in soft tissues of the combined strategies. Enhancement of vessel formation and maturation supports further investigation of this strategy.

Enhance wastewater biological treatment through the bacteria induced graphene oxide hydrogel

The interaction between bacteria and graphene-family materials like pristine graphene, graphene oxide (GO) and reduced graphene oxide (rGO) is such an elusive issue that its implication in environmental biotechnology is unclear. Herein, two kinds of self-assembled bio-rGO-hydrogels (BGHs) were prepared by cultivating specific Shewanella sp. strains with GO solution for the first time. The microscopic examination by SEM, TEM and CLSM indicated a porous 3D structure of BGHs, in which live bacteria firmly anchored and extracellular polymeric substances (EPS) abundantly distributed. Spectra of XRD, FTIR, XPS and Raman further proved that GO was reduced to rGO by bacteria along with the gelation process, which suggests a potential green technique to produce graphene. Based on the characterization results, four mechanisms for the BGH formation were proposed, i.e., stacking, bridging, rolling and cross-linking of rGO sheets, through the synergistic effect of activities and EPS from special bacteria. More importantly, the BGHs obtained in this study were found able to achieve unique cleanup performance that the counterpart free bacteria could not fulfill, as exemplified in Congo red decolorization and Cr(VI) bioreduction. These findings therefore enlighten a prospective application of graphene materials for the biological treatment of wastewaters in the future.

3D Clearing and Molecular Labeling in Plant Tissues

Plant histology and imaging traditionally involve the transformation of tissues into thin sections to minimize light scatter in opaque material, allowing optical clarity and high-resolution microscopy. Recently, new techniques in 3D tissue clearing, including PEA-CLARITY, have been developed to minimize light scatter within intact, whole samples. These techniques can achieve equivalent microscopic resolution to that of thin section imaging with the added benefit of maintaining the original 3D structure and position of biomolecules of interest. Furthermore, PEA-CLARITY is compatible with standard stains and immunohistochemistry, allowing molecular interrogation of intact, 3D tissues. This chapter outlines the current methods available for 3D histology in plants and details the materials, equipment, reagents, and procedure for the PEA-CLARITY technique.

Bioconjugated graphene oxide hydrogel as an effective adsorbent for cationic dyes removal

In this study, graphene oxide - cellulose nanowhiskers nanocomposite hydrogel was easily synthesized through covalent functionalization of cellulose nanowhiskers with graphene oxide via a facile approach. The nitrene chemistry applied for covalent functionalization of graphene oxide sheets. The surface morphology and chemical structure of the nanocomposite hydrogel were characterized by FTIR, TGA, Raman, XRD, elemental analysis and SEM. The UV/Visible absorption spectrum revealed that the obtained porous nanocomposite hydrogel can efficiently remove cationic dyes such as methylene blue (MB) and Rhodamine B (RhB) from wastewater with high absorption power. The adsorption process showed that 100% of MB and 90% of RhB have been removed and the equilibrium state has been reached in 15min for low concentration solutions in accordance with the pseudo-second-order model. Moreover, the sample exhibited stable performance after being used several times. High adsorption capacity and easy recovery are the efficient factors making these materials as good adsorbent for water pollutants and wastewater treatment.

Immunological and Differentiation Properties of Amniotic Cells Are Retained After Immobilization in Pectin Gel

Mesenchymal stromal cells from the human amniotic membrane (i.e., human amniotic mesenchymal stromal cells [hAMSCs]) of term placenta are increasingly attracting attention for their applications in regenerative medicine. Osteochondral defects represent a major clinical problem with lifelong chronic pain and compromised quality of life. Great promise for osteochondral regeneration is held in hydrogel-based constructs that have a flexible composition and mimic the physiological structure of cartilage. Cell loading within a hydrogel represents an advantage for regenerative purposes, but the encapsulation steps can modify cell properties. As pectin gels have also been explored as cell vehicles on 3D scaffolds, the aim of this study was to explore the possibility to include hAMSCs in pectin gel. Immobilization of hAMSCs into pectin gels could expand their application in cell-based bioengineering strategies. hAMSCs were analyzed for their viability and recovery from the pectin gel and for their ability to differentiate toward the osteogenic lineage and to maintain their immunological characteristics. When treated with a purposely designed pectin/hydroxyapatite gel biocomposite, hAMSCs retained their ability to differentiate toward the osteogenic lineage, did not induce an immune response, and retained their ability to reduce T cell proliferation. Taken together, these results suggest that hAMSCs could be used in combination to pectin gels for the study of novel osteochondral regeneration strategies.

Integrated Methods to Manufacture Hydrogel Microparticles Containing Viral-Metal Nanocomplexes with High Catalytic Activity

Controlled synthesis of small and catalytically active noble metal nanoparticles under mild aqueous conditions is an unmet challenge. Genetically modified tobacco mosaic virus (TMV) can serve as a preferential precursor adsorption and growth sites for the controlled synthesis of palladium (Pd) nanoparticles with high catalytic activity. Here we describe detailed methods for the synthesis of Pd-TMV nanocomplexes as well as their integration into polymeric hydrogel microparticle platforms with controlled dimensions via a simple replica molding process. Such Pd-TMV-containing hydrogel particles may be useful in environmental remediation of toxic chemicals such as carcinogenic dichromate ions.

Hybrid Structured Illumination Expansion Microscopy Reveals Microbial Cytoskeleton Organization

Recently developed tissue-hydrogel methods for specimen expansion now enable researchers to perform super-resolution microscopy with ∼65 nm lateral resolution using ordinary microscopes, standard fluorescent probes, and inexpensive reagents. Here we use the combination of specimen expansion and the optical super-resolution microscopy technique structured illumination microscopy (SIM) to extend the spatial resolution to ∼30 nm. We apply this hybrid method, which we call ExSIM, to study the cytoskeleton of the important human pathogen Giardia lamblia including the adhesive disc and flagellar axonemes. We determined the localization of two recently identified disc-associated proteins, including DAP86676 , which localizes to disc microribbons, and the functionally unknown DAP16263 , which primarily localizes to dorsal microtubules of the disc overlap zone and the paraflagellar rod of ventral axonemes. Based on its strong performance in revealing known and unknown details of the ultrastructure of Giardia, we find that ExSIM is a simple, rapid, and powerful super-resolution method for the study of fixed specimens, and it should be broadly applicable to other biological systems of interest.

Anionically reinforced hydrogel network entrapped fungal cells for retention of cadmium in the contaminated aquatic media

A novel biomass/polymer composite was fabricated by embedding Thamnidium elegans cells in acrylic network of p(3-Methoxyprophyl)acrylamide p(MPA) enriched with 2-Akrylamido-2-methyl-1-propane sulfonic acid (AMPS). Cd(II) retention potential of hydrogel (p(MPA-co-AMPS)) increased by 20.66% times after this enrichment. The gel matrix could be effectively entrapped the biomass and resulting sorbent applied to remove Cd(II) from water in batch and continuous modes. The main physico-chemical parameters are discussed in addition to characterization, regeneration and application studies of the suggested sorbent. Equilibrium occurred within 30 min and Langmuir model predicted the equilibrium data. Kinetics of Cd(II) removal onto immobilized biomass is modeled using the pseudo-second-order rate equation. Maximum monolayer sorption capacity was estimated to be 123.76 mg g^-1 at 25 °C. Designed composite was successfully applied for the removal of Cd(II) from industrial wastewater. EDTA and HNO₃ can be efficiently used for Cd(II) recovery and composite sorbent recycled for at least 12 cycles with nearly stable sorption performance.

Zwitterionic starch-based hydrogel for the expansion and "stemness" maintenance of brown adipose derived stem cells

Brown adipose derived stem cells (BADSCs) have become a promising stem cell treatment candidate for myocardial infarction because of their efficiently spontaneous differentiation capacity towards cardiomyocytes. The lack of existing cell passage protocols motivates us to develop a neotype 3D cell expansion technique for BADSCs. In this study, "clickable" zwitterionic starch based hydrogels are developed using methacrylate modified sulfobetaine derived starch with dithiol-functionalized poly (ethylene glycol) as crosslinker via the "thiol-ene" Michael addition reaction. Moreover, CGRGDS peptide is immobilized into the hydrogel via a similar "clickable" approach. Their Young's moduli range from 22.28 to 74.81 kPa depending on the concentration of precursor solutions. Excellent anti-fouling property is also presented owing to the introduction of zwitterionic moieties. BADSCs are homogeneously encapsulated in the hydrogels and then routinely cultured for 10 days. Results suggest a capacious cell proliferation and the extent increases with either the decrease of mechanical strength or the introduction of CGRGDS. More excitingly, the cell "stemness" is well maintained during this period and the expanded cells released from the hydrogels well keep the efficiently spontaneous cardiomyogenic differentiation capacity. Therefore, it is suggested that zwitterionic starch based hydrogel is able for the expansion and "stemness " maintenance of BADSCs.