Search

The development of injectable hydrogels for soft tissue regeneration has gained significant attention due to their minimally invasive application and ability to conform precisely to the shape of irregular tissue cavities. This study presents a novel injectable porous scaffold based on natural polymers that undergoes in situ crosslinking, forming a highly resilient hydrogel with tailorable mechanical and physical properties to meet the specific demands of soft tissue repair. By adjusting the formulation, we achieved a range of stiffness values that closely mimic the mechanical characteristics of native tissues while maintaining very high resilience (>90%). The effects of gelatin, alginate, and crosslinker concentrations, as well as porosity, on the hydrogel's properties were elucidated. The main results indicated a compression modulus range of 2.7–89 kPa, which fits all soft tissues, and gelation times ranging from 5 to 30 s, which enable the scaffold to be successfully used in various operations. An increase in gelatin and crosslinker concentrations results in a higher modulus and lower gelation time, i.e., a stiffer hydrogel that is created in a shorter time. In vitro cell viability tests on human fibroblasts were performed and indicated high biocompatibility. Our findings demonstrate that these injectable hydrogel scaffolds offer a promising solution for enhancing soft tissue repair and regeneration, providing a customizable and resilient framework that is expected to support tissue integration and healing with minimal surgical intervention. [ABSTRACT FROM AUTHOR]

In this work, porous poly (vinyl alcohol) (PVA) hydrogels with different pore sizes were fabricated using inorganic non‐metallic porogens by an environmentally friendly method, providing a potential solution for the field of wastewater treatment. PVA hydrogels have gained much attention in the field of wastewater treatment due to their excellent adsorption performance and porous network structure. However, the employment of inorganic non‐metallic salts as porogens for PVA hydrogels has received limited attention so far. In this study, porous PVA hydrogels were prepared by freeze‐thawing and freeze‐drying with sodium sulfate (Na2SO4) and calcium carbonate (CaCO3) as porogens. PVA‐Na exhibited denser network structure with the concentration of Na2SO4 solution increased, and the tensile stress was enhanced by about 45 times. Meanwhile, the tensile stress of PVA‐Ca was improved significantly from 0.06 to 1.67 MPa, and the network structure became looser after adding CaCO3. Moreover, a comprehensive investigation was conducted on the adsorption performance of porous PVA hydrogel for Congo red (CR). Finally, five adsorption models were fitted to investigate the adsorption mechanism of porous PVA hydrogels, in which the maximum adsorption capacity of CR by PVA‐Na‐0.5 was predicted to be 215 mg/g by the Langmuir isothermal model fitting. Highlights: The structure of PVA hydrogels was adjusted by Na2SO4 and CaCO3, respectively.The tensile stress of PVA‐Na with dense network structure increased 45 times.Compared to PVA‐FD, swelling equilibrium time of PVA‐Na reduced from 24 to 6 h.Equilibrium swelling rate of PVA‐Ca declined by half in comparison to PVA‐FD.Langmuir isothermal model predicted qmax of 215 mg/g for CR by PVA‐Na‐0.5. [ABSTRACT FROM AUTHOR]

The need for a long-term solution for filling the defects created during partial mastectomies due to breast cancer diagnosis has not been met to date. All available defect-filling methods are non-permanent and necessitate repeat procedures. Here, we report on novel injectable porous hydrogel structures based on the natural polymers gelatin and alginate, which are designed to serve for breast reconstruction and regeneration following partial mastectomy. The effects of the formulation parameters on the mechanical and physical properties were thoroughly studied. The modulus in compression and tension were in the range of native breast tissue. Both increased with the increase in the crosslinker concentration and the polymer–air ratio. Resilience was very high, above 93% for most studied formulations, allowing the scaffold to be continuously deformed without changing its shape. The combination of high resilience and low elastic modulus is favored for adipose tissue regeneration. The physical properties of gelation time and water uptake are controllable and are affected mainly by the alginate and N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) concentrations and less by the polymer–air ratio. In vitro cell viability tests were performed on mouse preadipocytes and indicated high biocompatibility. The minimally invasive nature of this approach, along with the excellent properties of the scaffold, will enable the filling of complex voids while simultaneously decreasing surgical costs and greatly improving patient well-being. [ABSTRACT FROM AUTHOR]

Water contamination from industrial dyes poses a significant threat to the environment and human health. This study focuses on the development of advanced porous cross‐linked chitosan‐based hydrogels and superparamagnetic hydrogel nanocomposites for efficient removal of indigo carmine (IC) dye from water. The hydrogels were cross‐linked using benzophenonetetracarboxylic dianhydride (BTDA) and incorporated functionalized magnetic iron nanoparticles (CP‐MNPs). A comparative study revealed that the superparamagnetic hydrogel nanocomposite exhibited superior performance in IC dye adsorption. Higher IC removal efficiencies were observed at lower amounts of cross‐linker, pH, and adsorbent dosage. The superparamagnetic hydrogel nanocomposite demonstrated superior IC dye adsorption compared with the chitosan hydrogel. The adsorption process followed a pseudo‐second‐order kinetic model and Langmuir isotherm model. Thermodynamic data indicated that the adsorption onto the superparamagnetic hydrogel nanocomposite was endothermic and spontaneous, making it a promising material for environmental applications. [ABSTRACT FROM AUTHOR]

The treatment of Cr(VI) wastewater containing hexavalent chromium is a difficult problem. The World Health Organization (WHO) "Drinking Water Quality Standard" stipulates that the maximum allowable limit of chromium in drinking water is 0.05 mg/L. It is very necessary to develop an adsorbent for efficiently removing Cr(VI) in water. In this paper, a composite porous hydrogel adsorbent of sepiolite/humic acid/polyvinyl alcohol@polypyrrole (SC/HA/PVA@PPy) was prepared by Pickering emulsion template-in-situ oxidative polymerization, and the enhancement effect of this design idea on the adsorption performance of PPy was studied with heavy metal ion hexavalent chromium Cr(VI) as the target adsorbate. The morphology and structure of the composite adsorbent were characterized by FESEM, EDX and FT-IR, which confirmed the successful compounding of PPy with SC/HA/PVA and effectively avoided the agglomeration of PPy. The adsorption performance of Cr(VI) was systematically studied through the experiments of solution pH, adsorption dosage, adsorption isotherm and adsorption kinetics. The adsorption capacity of SC/HA/PVA@PPy for Cr(VI) can reach 970.31 mg/g-PPy, which is about 44 times higher than that of pure PPy (21.87 mg/g), indicating that the experimental design can effectively avoid PPy agglomeration and exert its potential adsorption performance. The fitting results of adsorption isotherm are more in line with Langmuir model (R2 = 0.912, 0.975, 0.991 at three temperatures), and the thermodynamic parameters reveal that the adsorption process is a spontaneous endothermic process. The adsorption kinetics proved that the adsorption process of Cr(VI) mainly followed the pseudo-second-order kinetic model (R2 = 0.957). The regeneration study shows that the adsorbent can be recycled. In addition, according to the FESEM-EDX, FTIR and XPS analysis of the adsorbent before and after adsorption, the removal of Cr(VI) was mainly enhanced by ion exchange, electrostatic attraction and chemical reduction. The peak of Cr element in EDX spectrum after adsorption provide direct evidence for the adsorption of Cr(VI). SC/HA/PVA@PPy adsorbent has good adsorption performance and strong stability, which has great development prospects in wastewater treatment. [ABSTRACT FROM AUTHOR]

The development of injectable hydrogels for soft tissue regeneration has gained significant attention due to their minimally invasive application and ability to conform precisely to the shape of irregular tissue cavities. This study presents a novel injectable porous scaffold based on natural polymers that undergoes in situ crosslinking, forming a highly resilient hydrogel with tailorable mechanical and physical properties to meet the specific demands of soft tissue repair. By adjusting the formulation, we achieved a range of stiffness values that closely mimic the mechanical characteristics of native tissues while maintaining very high resilience (>90%). The effects of gelatin, alginate, and crosslinker concentrations, as well as porosity, on the hydrogel’s properties were elucidated. The main results indicated a compression modulus range of 2.7–89 kPa, which fits all soft tissues, and gelation times ranging from 5 to 30 s, which enable the scaffold to be successfully used in various operations. An increase in gelatin and crosslinker concentrations results in a higher modulus and lower gelation time, i.e., a stiffer hydrogel that is created in a shorter time. In vitro cell viability tests on human fibroblasts were performed and indicated high biocompatibility. Our findings demonstrate that these injectable hydrogel scaffolds offer a promising solution for enhancing soft tissue repair and regeneration, providing a customizable and resilient framework that is expected to support tissue integration and healing with minimal surgical intervention.

During recent years, the development of drug delivery systems based on polymers has created powerful carriers for smart application in nanomedicine for the treatment of diseases. Based on this, the design of polymers that contain various active functional groups to create a suitable interaction with the drug for its loading and release has been considered. Generally, more porosity for more drug loading, biocompatibility of the desired polymer and more water absorption lead to better performance in drug permeation and release.In this research, the preparation of a template with a high internal phase emulsion (PolyHIPEs) based on polyacrylamide grafting onto sodium alginate (SA) biopolymer via free radical polymerization and PolyHIPEs method of oil-in-water emulsion type is presented. In this work, porous hydrogel with high water swelling (absorption) was prepared by using different concentrations of acrylamide (AAm), surface active agent, cross-linking agent and initiator. The highest equilibrium water swelling value of synthetic porous hydrogel with HIPEs method was 280 g/g, while the water swelling value of prepared hydrogel without HIPEs method was 25 g/g. The open-cell porous hydrogel with water swelling of 280, has average pores of 5-10 μm, 200 nm windows and porosity of 80-85%. Modern instrumental methods such as SEM, AFM, FT-IR, BET and TGA were used to identify the porous hydrogel of PolyHIPEs. The loading and controlled release of the doxorubicin anticancer drug was performed on the optimum porous hydrogel in laboratory conditions. The results showed that smart SA-g-PAAm hydrogel is suitable for drug release at 41 °C and pH 5.5 (cancer cell conditions).

The need for a long-term solution for filling the defects created during partial mastectomies due to breast cancer diagnosis has not been met to date. All available defect-filling methods are non-permanent and necessitate repeat procedures. Here, we report on novel injectable porous hydrogel structures based on the natural polymers gelatin and alginate, which are designed to serve for breast reconstruction and regeneration following partial mastectomy. The effects of the formulation parameters on the mechanical and physical properties were thoroughly studied. The modulus in compression and tension were in the range of native breast tissue. Both increased with the increase in the crosslinker concentration and the polymer–air ratio. Resilience was very high, above 93% for most studied formulations, allowing the scaffold to be continuously deformed without changing its shape. The combination of high resilience and low elastic modulus is favored for adipose tissue regeneration. The physical properties of gelation time and water uptake are controllable and are affected mainly by the alginate and N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDC) concentrations and less by the polymer–air ratio. In vitro cell viability tests were performed on mouse preadipocytes and indicated high biocompatibility. The minimally invasive nature of this approach, along with the excellent properties of the scaffold, will enable the filling of complex voids while simultaneously decreasing surgical costs and greatly improving patient well-being.

To deal with intra‐abdominal sepsis, one of the major global causes of death in hospitalized patients, efficient abscess drainage is crucial. Despite decades of advances, traditional catheters have demonstrated poor drainage and absorption properties due to their simple tubular structures and their dense nonporous surface. Herein, inspired by porous sponges and fractal roots, a multifaceted hydrogel catheter with effective drainage, absorptive, and robust properties, is presented. Its unique fractal structures provide extensive internal branching and a high specific surface area for effective drainage, while the hierarchical porous structures provide a wide range of absorption capabilities. Additionally, its distinctive multi‐interpenetration network maintains robust and appropriate mechanical properties, even after absorption multiple times of liquid and mechanical disturbance, allowing for intact removal from the abdominal cavity without harm to the animal in vivo. Besides, the loaded antimicrobial peptides are capable of being released in situ to inhibit the potential for infections. In vivo experiments have demonstrated that this hydrogel catheter efficiently removes lethal abscesses and improves survival. It is believed that this innovative and practical catheter will create a future precedent for hydrogel drainage devices for more effective management of intra‐abdominal sepsis. [ABSTRACT FROM AUTHOR]

Abstract To deal with intra‐abdominal sepsis, one of the major global causes of death in hospitalized patients, efficient abscess drainage is crucial. Despite decades of advances, traditional catheters have demonstrated poor drainage and absorption properties due to their simple tubular structures and their dense nonporous surface. Herein, inspired by porous sponges and fractal roots, a multifaceted hydrogel catheter with effective drainage, absorptive, and robust properties, is presented. Its unique fractal structures provide extensive internal branching and a high specific surface area for effective drainage, while the hierarchical porous structures provide a wide range of absorption capabilities. Additionally, its distinctive multi‐interpenetration network maintains robust and appropriate mechanical properties, even after absorption multiple times of liquid and mechanical disturbance, allowing for intact removal from the abdominal cavity without harm to the animal in vivo. Besides, the loaded antimicrobial peptides are capable of being released in situ to inhibit the potential for infections. In vivo experiments have demonstrated that this hydrogel catheter efficiently removes lethal abscesses and improves survival. It is believed that this innovative and practical catheter will create a future precedent for hydrogel drainage devices for more effective management of intra‐abdominal sepsis.

Hexavalent chromium Cr(VI) is a typical harmful pollutant, which is carcinogenic or mutagenic to aquatic animals and humans. In this study, sepiolite/humic acid/polyvinyl alcohol@ polyaniline (SC/HA/PVA@PANI) composite porous hydrogel adsorbent was synthesized by Pickering emulsion template in situ chemical oxidative polymerization for adsorption of Cr(VI) from aqueous solution. The in situ polymerization of aniline at the Pickering emulsion interface and the unique three-dimensional network structure of the hydrogel act as an effective "confinement" for the growth of the polymer. The porous structure of the material acts as a water channel, which effectively accelerates the binding of the adsorbate to the adsorption sites, and significantly improves the adsorption rate and adsorption capacity. The adsorption capacity of PANI for Cr(VI) confined in three-dimensional network of composite porous SC/HA/PVA@PANI hydrogel reached 1180.97 mg/g-PANI, which increased about 27-fold compared the adsorption capacity of pure PANI (43.48 mg/g). It is shown that the experimental design effectively avoids the agglomeration of PANI and improves its potential adsorption performance. In addition, the analysis of FESEM-EDX, FT-IR, and XPS spectra before and after adsorption confirmed that the main adsorption mechanisms of Cr(VI) on SC/HA/PVA@PANI included ion exchange, electrostatic attraction, and redox reaction. In conclusion, SC/HA/PVA@PANI has good stability and excellent adsorption performance, which is a new type of Cr(VI) ion adsorbent with great potential. [ABSTRACT FROM AUTHOR]

Thermosensitive hydrogels have been receiving attention in the development of fire extinguishing agents due to their stimuli responsivity. Conventional hydrogels are limited by their slow response rate, and their wettability has not been studied systematically. In the present study, a concentrate of a thermosensitive porous system has been successfully synthesized by adding Na2CO3/CH3COOH as a foaming agent into the mixture of hydroxypropyl methylcellulose (HPMC)/polyethylene glycol (PEG)/chitosan (CS). The systems with different concentrations were obtained by diluting the concentrate with water. Thermosensitivity, surface tension and contact angle were characterized. In addition, spreadability, wettability and adhesivity were investigated systematically. Results showed that the systems with a concentration greater than 15 wt% exhibited outstanding performance of thermosensitivity and coagulability. A total of 20 wt% of the system has the best spreadability and wettability on the wood surface, most likely due to favorable contributions brought by both adequate viscosity and hydrophilicity. The adhesive force and surface-free energy of the pre-gel droplet that reached deposition on the wood surface decreased by 46.78% and 20.71%, respectively. The gel has a great capacity of water retention over a long period of time, which makes this porous gel the best system when it comes to its wettability and adhesiveness towards the chosen wood surface. The equilibrium surface tension decreased by 45.50% compared with water. HPMC/PEG/CS thermosensitive porous hydrogel with excellent wettability presented wide-ranging possibilities for the further development of fire suppression agents of fast phase-transition thermosensitive hydrogel. [ABSTRACT FROM AUTHOR]

The traditional 3D culture systems in vitro lack the biological and mechanical spatiotemporal stimuli characteristic to native tissue development. In our study, we combined porous polysaccharide-based hydrogel scaffolds with a bioreactor-type perfusion device that generates favorable mechanical stresses while enhancing nutrient transfers. MC3T3E1 mouse osteoblasts were seeded in the scaffolds and cultivated for 3 weeks under dynamic conditions at a perfusion rate of 10 mL min−1. The spatial distribution of the cells labeled with superparamagnetic iron oxide nanoparticles was visualized by MRI. Confocal microscopy was used to assess cell numbers, their distribution inside the scaffolds, cell viability, and proliferation. The oxygen diffusion coefficient in the hydrogel was measured experimentally. Numerical simulations of the flow and oxygen transport within the bioreactor were performed using a lattice Boltzmann method with a two-relaxation time scheme. Last, the influence of cell density and spheroid size on cell oxygenation was investigated. The cells spontaneously organized into spheroids with a diameter of 30–100 μm. Cell viability remained unchanged under dynamic conditions but decreased under static culture. The cell proliferation (Ki67 expression) in spheroids was not observed. The flow simulation showed that the local fluid velocity reached 27 mm s−1 at the height where the cross-sectional area of the flow was the smallest. The shear stress exerted by the fluid on the scaffolds may locally rise to 100 mPa, compared with the average value of 25 mPa. The oxygen diffusion coefficient in the hydrogel was 1.6 × 10 − 9 m2 s−1. The simulation of oxygen transport and consumption confirmed that the cells in spheroids did not suffer from hypoxia when the bioreactor was perfused at 10 mL min−1, and suggested the existence of optimal spheroid size and spacing for appropriate oxygenation. Collectively, these findings enabled us to define the optimal conditions inside the bioreactor for an efficient in vitro cell organization and survival in spheroids, which are paramount to future applications with organoids. [ABSTRACT FROM AUTHOR]

The present study was aimed at curating a porous KCl crosslinked hydrogel with purified subabul galactomannans (SG) from the defatted seeds of Leucaena leucocephala (subabul) and κ‐carrageenan (κC) by inducing whey protein isolate (WPI). WPI showed 345% foam overrun and minimal foam drainage (%) at 70°C when whipped for 5 min at pH 6.8 in the hydrogel prepared with 6.5% w/v SG + 1% w/v κC + 0.63% w/v KCl + 2% w/v WPI. The SG and WPI incorporated porous hydrogel (SGWP) showed maximum G′ (3010 Pa) and frequency independence (>30 Hz) at 65°C. NMR (1H), scanning electron microscopy, and thermal characterization of SGWP showed a crosslinked microporous gel network formation. SGWP had high water uptake rate (Q) (432%) at 45°C. The stability of SGWP at neutral pH and high temperature (65°C) added an impetus to this study as it could be used for a wide range of applications. Hence the protein–polysaccharide complexation improvised the functional properties of the porous hydrogels. The results suggested a possible valorization of galactomannans from subabul, a forest resource, into a porous hydrogel suitable as a matrix for delivery of bioactive(s) or an aerogel for multifarious industrial applications. Practical Application: A porous hydrogel is defined as a solid, or collection of solid bodies, with sufficient open space to enable a fluid to pass through or around them. Leucaena leucocephala seed (forest resource) galactomannans are non‐starch polysaccharides having weak gelling capacity. Whey protein isolates (WPI) are a dairy industry byproduct having excellent foaming properties. Incorporation of WPI in the hydrogel prepared with subabul galactomannan and κ‐carrageenan using KCl as a crosslin could form a stable porous structure having high water uptake rate (Q) at neutral pH and elevated temperature. The hydrogel so developed could be a step toward circular economy. [ABSTRACT FROM AUTHOR]

Hematopoietic stem cell (HSC) transplantation remains the most effective therapy for hematologic and lymphoid disorders. However, as the primary therapeutic cells, the source of HSCs has been limited due to the scarcity of matched donors and difficulties in ex vivo expansion. Here, we described a facile method to attempt the expansion of HSCs in vitro through a porous alginate hydrogel-based 3D culture system. We used gelatin powders as the porogen to create submillimeter-scaled pores in alginate gel bulk while pre-embedding naïve HSCs in the gel phase. The results indicated that this porous hydrogel system performed significantly better than those cultured via conventional suspension or encapsulation in non-porous alginate hydrogels in maintaining the phenotype and renewability of HSCs. Only the porous hydrogel system achieved a two-fold growth of CD34+ cells within seven days of culture, while the number of CD34+ cells in the suspension system and nonporous hydrogel showed different degrees of attenuation. The expansion efficiency of the porous hydrogel for CD34+CD38- cells was more than 2.2 times that of the other two systems. Mechanistic study via biophysical analysis revealed that the porous alginate system was competent to reduce the electron capture caused by biomaterials, decrease cellular oxygen stress, avoid oxidative protection, thus maintaining the cellular phenotype of the CD34+ cells. The transcriptomic analysis further suggested that the porous alginate system also upregulated the TNF signaling pathway and activated the NF-κB signaling pathway to promote the CD34+ cells' survival and maintain cellular homeostasis so that renewability was substantially favoured. • The reported porous hydrogel system performs significantly better in terms of maintaining the phenotype and renewability of HSCs than those cultured via conventional suspension or encapsulation in non-porous alginate hydrogel. • The reported porous alginate system is competent to reduce the electron capture caused by biomaterials, decrease cellular oxygen stress, avoid oxidative protection, and therefore maintain the cellular phenotype of the CD34+ cells. • The reported porous alginate system can also upregulate the TNF signaling pathway and activate the NF-κB signaling pathway to promote the CD34+ cells' survival and maintain cellular homeostasis so that the renewability is substantially favored.. [Display omitted] [ABSTRACT FROM AUTHOR]

We present the fabrication and application of a magnetically actuated, macro-porous, drug–delivery hydrogel exhibiting significant reversible volume change (down to 55% of its original size) in response to a small magnetic field (23 Gauss) from a permanent magnet. When integrating the hydrogel in a microchannel, the system demonstrates a magnetically regulated flow dynamics, showing a wide range of controllable flow rate from 10 to 100 µL/s. It is fabricated via a straightforward and economical process in which macro-pores are incorporated into the hydrogel by generating micro-bubbles during its crosslinking process. The resulting hydrogel enables simultaneous control over liquid flow and drug release rate. [ABSTRACT FROM AUTHOR]

The indoor formaldehyde concentration is in trace quantities; however, it considerably deteriorates indoor air quality and poses a serious threat to human health and ecosystems. Since current formaldehyde analyzers are only suitable for high-concentration detection or are expensive, there is a pressing need for an easy-to-use, storable, and highly sensitive formaldehyde detector. In this study, we developed a colorimetric sensing sphere using affordable and eco-friendly sodium alginate as a porous matrix. Polyethyleneimine, a molecule rich in amino groups, and an indicator are embedded in the matrix to create a core-shell structured, responsive porous hydrogel colorimetric sensor for indoor formaldehyde detection. The sensing sphere exhibits high sensitivity and excellent detection limits at a polyethyleneimine to pH agent mass ratio of 23:1, reaching a sensitivity of 0.02 mg/m3 and a detection limit of 0.06 mg/m3. The sensing sphere demonstrates superior selectivity among common indoor pollutants and remains unaffected by temperature (up to 70 ℃) or humidity (20–80 %) changes. Moreover, the core-shell structure of the colorimetric sensor ball addresses the poor stability and storage issues. The core-shell structure resists interference from external environmental changes, offering remarkable stability for 6 months and longer, hence, facilitating easy transportation and storage. The colorimetric sensing sphere is simple, cost-effective, and reliable for ordinary households, thus maintaining the indoor air quality and health of residents. [Display omitted] • A cost-effective and eco-friendly formaldehyde sensing substrate with a wide pore structure was prepared. • Grafting low-cost, amino-rich PEI enhances sensitivity, detection time, and limits. • Core-shell boosts accuracy, prolongs life, resists external interference effectively. • Indoor conditions don't impact detection, demonstrating good selectivity. [ABSTRACT FROM AUTHOR]

Exogenous electrical stimulation (ES) can significantly enhance the wound healing acceleration. However, most power-generating devices and materials are limited due to structural complexity, external power dependence, and low bio-safety. Here, we design and synthesize a porous hydrogel with gas-solid contact-separation triboelectricity (GSHL). It exhibits excellent physicochemical properties and bio-safety. Also, its inner pores provide a gas-solid interface, which generates a stable self-powered triboelectric potential difference due to the deformation of the interior pores when pressed by the motion of hosts. This exogenous triboelectric stimulation can enhance the proliferation, migration, and adhesion of keratinocytes. In vivo experiments show that GSHL can generate ES at wound bed in situ through the movements of rats, accelerate re-epithelization, and enhance collagen deposition, thereby enhancing the healing of skin wounds. Compared to traditional methods that depending on an external power source to achieve ES for wound healing, this study introduces a novel triboelectric method that is self-powered solely through the intrinsic movement of the organism without any external electrical input. [Display omitted] • Porous hydrogel with gas-solid contact-separation triboelectricity (GSHL) can generate triboelectricity. • GSHL exhibits excellent physicochemical properties and bio-safety as wound dressing. • GSHL can provide exogenous electrical stimulation through the motion of host to accelerate wound healing. [ABSTRACT FROM AUTHOR]

Porous hydrogel dressings show breathability and possibility to carry and release basic fibroblast growth factor (bFGF) to promote wound healing. However, the difficult replacement may lead to the secondary damage. Thus, there is an urgent need to develop a method platform to control the degradation rate of hydrogel, so as to realize the on-demand replacement. The present study fabricated a porous hydrogel from co-polymized N,N′ -bis(acryloyl) cystamine (BAC), allyl polyethylene glycol 500 (APEG500) and acrylic acid (AA) with the presence of polycaprolactone (PCL). BAC contains disulfide bond, which crosslinked the hydrogel. The pore size of the porous hydrogel was 400–600 μm. Higher content of BAC indicated higher crosslinking density, which reduced swelling ratio of hydrogel, while promoted hydrogel storage modulus. At the same time, the presence of PCL reduced swelling ratio of hydrogel, while promoted hydrogel mechanical properties, endowing hydrogel with tough feature. Porous hydrogels that crosslinked by disulfide bonds immersed in glutathione solution were found to degrade spontaneously and quickly due to the response to glutathione. Both crosslinking density and PCL content affected the degradation rate. The porous hydrogel carrying bFGF was applied to wound, promoting angiogenesis, thus accelerating wound healing within 12 d. Due to the spontaneous and rapid degradation of optimized porous hydrogel on wound within 3 days, there was no operation of removing dressing during treatment, avoiding damage during dressing replacement. [ABSTRACT FROM AUTHOR]

[Display omitted] Conductive hydrogel-based flexible electronics have attracted immense interest in wearable sensor, soft robot and human–machine interface. However, the application of hydrogels in flexible electronics is limited by the deterioration of mechanical and electrical properties due to freezing at low temperature and desiccation after long-term use. Meanwhile, flexible electronics based on hydrogel are usually not breathable, which has a great impact on wearing comfort and signal stability in long-term sensing. In this work, an adjustable porous gelatin/polypyrrole/reduction graphene oxide (Gel/PPy/rGO) organohydrogel with high breathability (14 g∙cm−2∙h−1), conductivity (5.25 S/m), mechanical flexibility, anti-freezing and long-term stability is prepared via the combination method of biological fermentation and salt-out toughening crosslinking. The sensor fabricated from the prepared porous organohydrogel exhibits excellent sensing sensitivity, fast response ability, and good endurance, which monitors both weak and intense human activities effectively like finger bending, elbow bending, walking and running, and tiny pulse beating. A pressure sensor array prepared from the porous organohydrogel detects pressure variation in 2D sensitively. Furthermore, the porous organohydrogel is utilized as flexible electrodes for the accurate collection and recognition of human physiological signals (EMG, ECG) and as an interface between human and machine. [ABSTRACT FROM AUTHOR]

Thermosensitive hydrogels have been receiving attention in the development of fire extinguishing agents due to their stimuli responsivity. Conventional hydrogels are limited by their slow response rate, and their wettability has not been studied systematically. In the present study, a concentrate of a thermosensitive porous system has been successfully synthesized by adding Na2CO3/CH3COOH as a foaming agent into the mixture of hydroxypropyl methylcellulose (HPMC)/polyethylene glycol (PEG)/chitosan (CS). The systems with different concentrations were obtained by diluting the concentrate with water. Thermosensitivity, surface tension and contact angle were characterized. In addition, spreadability, wettability and adhesivity were investigated systematically. Results showed that the systems with a concentration greater than 15 wt% exhibited outstanding performance of thermosensitivity and coagulability. A total of 20 wt% of the system has the best spreadability and wettability on the wood surface, most likely due to favorable contributions brought by both adequate viscosity and hydrophilicity. The adhesive force and surface-free energy of the pre-gel droplet that reached deposition on the wood surface decreased by 46.78% and 20.71%, respectively. The gel has a great capacity of water retention over a long period of time, which makes this porous gel the best system when it comes to its wettability and adhesiveness towards the chosen wood surface. The equilibrium surface tension decreased by 45.50% compared with water. HPMC/PEG/CS thermosensitive porous hydrogel with excellent wettability presented wide-ranging possibilities for the further development of fire suppression agents of fast phase-transition thermosensitive hydrogel.

The traditional 3D culture systems in vitro lack the biological and mechanical spatiotemporal stimuli characteristic to native tissue development. In our study, we combined porous polysaccharide-based hydrogel scaffolds with a bioreactor-type perfusion device that generates favorable mechanical stresses while enhancing nutrient transfers. MC3T3E1 mouse osteoblasts were seeded in the scaffolds and cultivated for 3 weeks under dynamic conditions at a perfusion rate of 10 mL min−1. The spatial distribution of the cells labeled with superparamagnetic iron oxide nanoparticles was visualized by MRI. Confocal microscopy was used to assess cell numbers, their distribution inside the scaffolds, cell viability, and proliferation. The oxygen diffusion coefficient in the hydrogel was measured experimentally. Numerical simulations of the flow and oxygen transport within the bioreactor were performed using a lattice Boltzmann method with a two-relaxation time scheme. Last, the influence of cell density and spheroid size on cell oxygenation was investigated. The cells spontaneously organized into spheroids with a diameter of 30–100 μm. Cell viability remained unchanged under dynamic conditions but decreased under static culture. The cell proliferation (Ki67 expression) in spheroids was not observed. The flow simulation showed that the local fluid velocity reached 27 mm s−1 at the height where the cross-sectional area of the flow was the smallest. The shear stress exerted by the fluid on the scaffolds may locally rise to 100 mPa, compared with the average value of 25 mPa. The oxygen diffusion coefficient in the hydrogel was 1.6×10−9 m2 s−1. The simulation of oxygen transport and consumption confirmed that the cells in spheroids did not suffer from hypoxia when the bioreactor was perfused at 10 mL min−1, and suggested the existence of optimal spheroid size and spacing for appropriate oxygenation. Collectively, these findings enabled us to define the optimal conditions inside the bioreactor for an efficient in vitro cell organization and survival in spheroids, which are paramount to future applications with organoids.

BACKGROUND: Hydrogel scaffolds are one of the ideal materials for three-dimensional cell culture. However, the dense network structure in the hydrogel can significantty inhibit the proliferation and extension of cells, and the porous structure in the hydrogel scaffolds can alleviate these problems. OBJECTIVE: To investigate the method of constructing three-dimensional cellular porous hydrogel scaffold with methacrylate anhyd ride gelatin as scaffold material and polyethylene oxide solution as pore-forming agent, and the effect of porous hydrogel scaffolds on cellular behavior. METHODS: Methacrylate anhydride gelatin hydrogel solution and polyethylene oxide solution were prepared, and mixed in a volume ratio of 4 :1, 3:1, 2:1, and 1:1, separately. After adding bone marrow mesenchymal stem cells, a three-dimensional porous hydrogel scaffold that could carry cells were designed and constructed to ch aracterize the microscopic morphology and mechanical properties of the scaffold. The live/dead staining was utilized to observe cell compatibility, and cytoskeleton staining was applied to observe cell morphology. RESULTS AND CONCLUSION: (1) The scanning electron microscope showed that the cross-sections of scaffolds of each group displayed uniformly distributed porous structures, and the pores were connected to each other. The pores were oval-like or round-like. As the proportion of polyethylene oxide solution increased, the pore size of the scaffolds and porosity increased. (2) Multi-frequency strain curves showed that the strain of scaffolds of each group could reach more than 40%, among which the strain of the scaffold with a volume ratio of 1:1 could reach 60%. As the proportion of polyethylene oxide solution increased, the storage modulus of the scaffold decreased, and the mechanical strength of the volume ratio 1:1 scaffold was poor, and it could barely maintain the shape of the scaffold. (3) The live/dead staining of 14 days in vitro culture showed that the survival rate of cells of scaffolds in each group was >85%. (4) Staining of the cytoskeleton cultured for 14 days in vitro showed that most of the cells in the scaffold with a volume ratio of 3:1 were short spindle-shaped, and the cells in the scaffold with a volume ratio of 2:1 and 1:1 were star-shaped or long spindle-shaped. A wide range of connections was established among cells. (5) Three dimensional cell-carrying porous hydrogel scaffold can significantly promote the spreading and proliferation of bone marrow mesenchymal stem cells. Porous hydrogels with a volume ratio of 2:1 have both mechanical strength and biologica l propertes and can be a good platform for three-dimensional cell culture. [ABSTRACT FROM AUTHOR]

Adipose derived stem cell (ASC) spheroids show enhanced cellular viability and paracrine function to promote tissue regeneration and cell therapy effect. However, efficient preparation of numerous ASC spheroids, as well as convenient application on skin wound remains a challenge. The present study explored a new function of frequently-used polymer, Poly (N-isopropylacrylamide) (PNIPAM), developing a simple but efficient method based on PNIPAM to produce numerous ASC spheroids and apply them towards wound healing. PNIPAM-based porous hydrogel that crosslinked with disulfide bonds was fabricated, showing pore size of 300 μm at 37 °C. ASCs seeded into porous hydrogel spontaneously aggregated inside the inner pores to form a large number of spheroids. Higher cell seeding density could produce larger size of spheroids, which showed up-regulated paracrine secretion. After spheroids production, the porous hydrogel became a solution within 25 min after the addition of glutathione at 15 °C. The PNIPAM-based polymer solution carrying the produced ASC spheroids gelled again within 80 s at 33 °C and could tightly attach on skin. The in vivo wound healing evaluation illustrated that ASC spheroids promoted M2 polarization of macrophages, and effectively inhibited the local inflammatory response of wounds, thus accelerating wound healing. Thus, for one thing, this method was expected to realize the industrialized manufacturing of a large number of stem cell spheroids. For another, the spheroids produced by the present method could be easily collected and applied for biomedical engineering.

Developing a packaging material with integrated cushioning, intelligent and active functions is highly desired but remains challenging in the food industry. Here we show that a sponge-like porous hydrogel with pH-indicating and antibacterial additives can meet this requirement. We use polyvinyl alcohol and chitosan as the primary polymers to construct a hydrogel with hierarchical structures through a freeze-casting method in combination with salting-out treatment. The synergy of aggregated polymer chains and the sponge-like porous structure makes the hydrogel resilient and efficient in energy absorption. It also enables rapid movement of molecules/particles and fast reaction due to the large specific surface area of the pore structures and the large amount of free water in it, leading to a sensitive pH-indicating function. The hydrogel shows an obvious color variation within a wide pH range in 3 min. The silver nanoparticles are fixed in the dense polymer networks, enabling a lasting release of silver ions. The porous structure makes the silver ion reach the protected item in a short time, achieving an antibacterial effect against S. aureus and E. coli with little cytotoxicity. This work paves the way for fabricating multifunctional hydrogels for diverse advanced packaging systems. [ABSTRACT FROM AUTHOR]

• Fermentation is extremely efficient at preparing porous materials on a large scale. • The pore size of FPHs made under mild conditions can be easily adjusted by time. • FPH-30 exhibits high evaporation rate of 1.594 kg m−2 h−1 and η of 95.15%. • FPHs show excellent composite and mechanical stability, and self-cleaning property. Solar interfacial evaporation is a promising technology for the purification of seawater and polluted water using sustainable solar energy. An adjustable shape and internal-channel size of photothermal evaporation material are essential for regulating heat utilization and water supply rate to three-dimensional (3D) evaporation device. However, a simple method for the preparation process is rarely reported to date. Inspired by bread making, a straightforward fermentation method is applied to the preparation of adjustable porous hydrogel as photothermal evaporation materials. It only takes 40 min to ferment and three simple freeze-thawing cycles to construct the final hydrogel materials. A mold can be used to easily adjust the external shape of the fermentation porous hydrogels (FPHs). The internal-channel size of FPHs can be simply tuned by the fermentation time. The flexible porous structure endows FPHs with excellent photothermal evaporation capability and makes it easy to meet the requirements of water supply rates under the light intensity of different latitudes for water treatment. [ABSTRACT FROM AUTHOR]

Herein, a potential hydrogel based on sodium alginate (SA) integrated with polyethyleneimine (PEI) was fabricated and employed for the elimination of methyl blue (MB) in aqueous media. The SA/PEI hydrogel demonstrated excellent removal performance for MB, i.e. ~99% of MB could be removed from water within ~30 min using 0.5 g/L SA/PEI hydrogel at 100 mg/L initial concentration. The SA/PEI hydrogel presented maximum adsorption capacity for MB as-high as 400.0 mg/g with the adsorption isotherm and kinetics abide with the Langmuir isotherm model and pseudo second-order kinetics, respectively. The adsorption process followed through chelation between the functionality of the hydrogel and MB as-confirmed by the X-ray photoelectron spectroscopy (XPS) analysis. After four consecutive adsorption/desorption cycles, the adsorption capacity of the SA/PEI hydrogel remained up to ~60% of its adsorption capacity in first cycle. Thus, being a cost-effective and eco-friendly material, the SA/PEI hydrogel can be a potential adsorbent in the decontamination of MB in wastewater. Unlabelled Image • Amine functionalized sodium alginate hydrogel was fabricated. • The hydrogel proved to be an excellent adsorbent for methyl blue. • Amine groups from PEI served as active sites to bind MB. • Chelation between active sites and MB was the key for the adsorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrophilic boronate affinity imprinted hydrogels were constructed via Pickering O/W HIPEs microreactor. • The new multi-functional emulsifier were designed with excellent emulsifying and self-initiating property. • Sorbents exhibit fast capture kinetics, large uptake capacity, and outstanding selectivity. • Sorbents possess uniform boronate affinity imprinted sites for selective separation of Naringin. Hydrogel-based imprinted materials with specific-recognition and ultrafast transport have been considered as one of the most promising sorbents in the selective separation fields. Nonetheless, the traditional hydrogel imprinted sorbents still facing the low-level interfacial consistency between substrate polymer and imprinted sites, unordered arrangement and easy agglomeration of recognizing sites on hydrogel matrix, causing poor selectivity of specific molecular transport. For the first time, the one-step RAFT Pickering HIPEs emulsion imprinted methods were designed to fabricate porous hydrophilic boronate affinity imprinted hydrogels (POH-BA-MIPs) for the specific separation and purification of Naringin (NRG). As expected, the novel RAFT solid emulsifier can not only enhance the emulsion stability and mechanical performance of the hydrogel, but also introduce the self-initiating function. Benefiting from the hydrogel's porous structure and the highly accessible and uniform imprinted sites via Pickering emulsion template, the POH-BA-MIPs exhibited strong binding affinity and selectivity to the targeted molecules. The maximum equilibrium adsorption capacity of POH-BA-MIPs were 53.27 µmol g−1 at 308 K within 360 min. The kinetic nonlinear pseudo-second-order model (R 2 = 0.997) can well explain the adsorption kinetic than pseudo-first-order model (R 2 = 0.986), indicating that chemisorption is mainly the rate-limiting step. Besides, the adsorption amounts of POH-BA-MIPs were 3.74 times higher than that of non-imprinted adsorbents (POH-BA-NIPs). After six consecutive adsorption–desorption cycles, the obtained POH-BA-MIPs demonstrated considerable reusability, retaining 91.28 % of the initial adsorption capacity. Meanwhile, the coarse NRG products can be effectively purified to 93.16 %. The obtained purified NRG had better antibacterial performance against Staphylococcus aureus. This work provides a novel strategy for constructing porous boronate affinity imprinted hydrogels for specific capture of targeted flavonoid molecules, which exhibited broad practical application potential. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mathematical tools are made good use of realizing the screening and optimization of chemical experiment conditions in terms of Microorganism Inspired Porous Hydrogel. • Box-Behnken design-based response surface methodology and artificial neural network coupled genetic algorithm were herein employed to optimize and predict the optimal preparation conditions. • It can accurately predict the best experimental results without performing hundreds of experiments. • Mathematical methods solve the related problems of linear and nonlinear data processing. To optimize the synthetic process of microorganism inspired multistage porous hydrogel, the mathematical analysis strategies was applied to select the optimal experimental parameters. One-factor-at-a-time (OFAT) design was used to optimize the preparation process of yeast fermentation multistage porous hydrogels. The analysis of variance (ANOVA) was applied to determine the significant influencing factors, and the results revealed that the mass ratio of yeast to glucose (R yeast/glucose), gelation temperature of yeast fermentation (T gelation) and reaction time (t reaction) had a significant influence on responses. Box-Behnken design (BBD) based response surface methodology (RSM) was used to design experiments and build the relationship between the input parameters and output responses. Ideal point method was used to transform a multi-objective optimization problem into a single-objective optimization problem. Artificial neural network (ANN) coupled genetic algorithm (GA) were employed to further optimize and predict the optimal preparation conditions of yeast fermentation multistage porous hydrogels. The results showed ANN coupled GA was a more effective tool in the modelling and optimization of the preparation of yeast fermentation multistage porous hydrogels. The optimized preparation conditions are R yeast/glucose 1.84, T gelation 25.00 °C, t reaction 239.97 min. These values are expected to give us the minimum density, the maximum swelling degree and compressive strength. The research content of this paper provides theoretical support and factual basis for process optimization with complex influencing factors. [ABSTRACT FROM AUTHOR]

Type 1 diabetes-mellitus (T1DM) is characterized by damage of beta cells in pancreatic islets. Cell-sheet engineering, one of the newest therapeutic approaches, has also been used to create functional islet systems by creating islet/beta cell-sheets and transferring these systems to areas that require minimally invasive intervention, such as extrahepatic areas. Since islets, beta cells, and pancreas transplants are allogeneic, immune problems such as tissue rejection occur after treatment, and patients become insulin dependent again. In this study, we aimed to design the most suitable cell-sheet treatment method and macrocapsule-device that could provide long-term normoglycemia in rats. Firstly, mesenchymal stem cells (MSCs) and beta cells were co-cultured in a temperature-responsive culture dish to obtain a cell-sheet and then the cell-sheets macroencapsulated using different concentrations of alginate. The mechanical properties and pore sizes of the macrocapsule-device were characterized. The viability and activity of cell-sheets in the macrocapsule were evaluated in vitro and in vivo . Fasting blood glucose levels, body weight, and serum insulin & C-peptide levels were evaluated after transplantation in diabetic-rats. After the transplantation, the blood glucose level at 225 mg dl -1 on the 10th day dropped to 168 mg dl -1 on the 15th day, and remained at the normoglycemic level for 210 days. In this study, an alginate macrocapsule-device was successfully developed to protect cell-sheets from immune attacks after transplantation. The results of our study provide the basis for future animal and human studies in which this method can be used to provide long-term cellular therapy in T1DM patients., (Creative Commons Attribution license.)

Generating electricity in hydrogel is very important but remains difficult. Hydrogel with electricity generation capability is more capable in bio-relevant tasks such as tissue engineering, artificial skin, or medical treatment, because electricity is indispensable in regulating physiological activities. Here, a porous and phase blending hydrogel structure for effective piezoionic electricity generation is developed. Dynamic electric field is generated taking advantage of the difference in streaming speeds of sodium and chloride in the material. Microscopic porosity and hydrophilic-hydrophobic phase blending are the two key factors for prominent piezoionic performance. Voltages as high as 600 mV are first realized in hydrogels in response to medical ultrasound stimulation. The hydrogel structure is also subjective to effective substance exchange and can actively enrich proteins from surroundings under mechanical stimuli. Preliminary applications in neural stimulation, constructing complex spatial-temporal chemical and electric field distribution patterns, mimetic tactile sensor, sample pretreatment in fast detection, and enzyme immobilization are demonstrated., (© 2023 Wiley-VCH GmbH.)

Graphical abstract Highlights • A new bio-based CMC/PAM composite hydrogel was prepared as a bioadsorbent. • Superior adsorption property of CuII, PbII and CdII ions was identified. • The adsorbed CuII ions were in situ reduced to form the Cu NPs-loaded hydrogel. • The CuII NPs-loaded hydrogel was efficiently used for the reduction of 4-NP. Abstract A new bio-based bilateral hydrogel containing carboxymethyl cellulose (CMC) and polyacrylamide (PAM) was prepared for the wastewater remediation. The obtained CMC/PAM composite hydrogel reveals a strong single-ion affinity for copper (CuII), lead (PbII) and cadmium (CdII) ions, as well as multi-ion absorbability with its equilibrium data following the Langmuir adsorption model and its adsorption process abiding by a pseudo-second-order kinetics. To demonstrate its recycled use for the metal ions, the adsorbed CuII ions in the hydrogel were reduced in situ to form homogeneously dispersed Cu nanoparticles (NPs), leading to the Cu NPs-loaded CMC/PAM hydrogel. Reduction of 4-nitrophenol to 4-aminophenol with high efficiency was successfully achieved by this Cu NPs-loaded CMC/PAM hydrogel, verifying the hydrogel's dual functionalities towards the wastewater treatment and catalytic application. [ABSTRACT FROM AUTHOR]

Anionic hydrogel was prepared by free radical copolymerization of acrylamide and acrylic acid. The anionic groups acted as adsorption sites to load Ni(II) ions and the subsequent reduction of loaded Ni(II) ions into nanoparticles enabled the prepared hydrogels to act template for the preparation of nanostructured Ni particles. The characteristics of the prepared hydrogel and hydrogel–nickel nanoparticle composite were studied with Fourier transform infrared spectroscopy, transmission electron microscopy, thermal gravimetric analysis, X-ray photoelectron spectroscopy and X-ray diffraction technique. Swelling behaviour of hydrogel in aqueous medium was analysed by gravimetric analysis. Catalytic performance of the prepared poly(acrylamide-co-acrylic acid)–nickel nanoparticle hydrogel composite was investigated in the reduction of 4-nitrophenol (4-NP). Effects of temperature and catalyst dose on the reduction rate were also studied. Activation energy (Ea) for the reduction of 4-NP was found to be 43.46 kJ/mol. A maximum reduction rate of 0.40 min−1 was observed at room temperature. [ABSTRACT FROM AUTHOR]

Highlights • Gelatin was used to modify the textural properties and porosity of egg white gel. • Addition of gelatin at 0.3% improved the firmness and WHC of gels. • Depletion of gelatin via leaching into water yielded highly porous egg white gels. • Electron microscopy showed a more open structure for gelatin-depleted hydrogels. • Highly porous egg white gels can be used as promising bioactive delivery systems. Abstract In the present study, composite egg white/gelatin hydrogels were produced and their porosity was increased through the subsequent removal of gelatin by leaching into water. The composite gel with 0.5% gelatin showed a higher degree of swelling than did the control gelatin-free sample after 60 min of immersion in an aqueous medium which was ascribed to the formation of capillary channels due to gelatin leaching. The composite gel containing 0.3% gelatin showed the highest water-holding capacity and firmness indices among all samples. Gel porosity decreased with increasing gelatin content. However, after gelatin depletion, higher concentrations of gelatin yielded hydrogels with higher porosity, as confirmed by scanning electron microscopy. Based on Fourier transform infra-red spectroscopy, it was concluded that the count of hydrogen bonds decreased after gelatin depletion. X-ray diffraction analysis indicated that intermolecular interaction between gelatin and egg white proteins had taken place in the amorphous phase. [ABSTRACT FROM AUTHOR]

A novel porous hydrogel adsorption material, called PAM/PAA/PDMTM gel, has been developed for the removal of heavy metal ions in complex systems. The gel is composed of polyacrylamide, polyacrylic acid, and poly(2,4-dimercapto-6-mercaptopropenyl-1,3,5-triazine) monomer. This hydrogel material features a large pore structure, abundant active functional groups, high swelling properties, good thermal stability, and remarkable regeneration ability. More importantly, the hydrogels contain a variety of active groups, they show good complex adsorption properties for heavy metals. The PAM/PAA/PDMTM gel demonstrated excellent adsorption performance, with the maximum adsorption capacity of Cu2+, Cd2+ and Pb2+ reaching 92.33, 110.08 and 200.97 mg g−1 (pH 5, 298 K), respectively. And the adsorption was in accord with the pseudo-second-order model and Langmuir model. Notably, the PAM/PAA/PDMTM gel also demonstrated remarkable adsorption capacity for Pb even in soil, making it an efficient adsorption material for removing heavy metals from both water and soil samples. • A porous hydrogel containing thiol and carboxyl groups was prepared. • The hydrogel has an excellent performance on removing Cu2+, Cd2+ and Pb2+ from solution. • The hydrogel has larger adsorption capacity. • The hydrogel shows a higher adsorption and removal efficiency for Pb from soil. [ABSTRACT FROM AUTHOR]

Handy and disposable point-of-care diagnostics facilitate the early screening of severe diseases in resource-limited areas. To address urgent needs in inconvenient sites, a simple colorimetric diagnostic device equipped with a capillary tube with porous hydrogel and immunocomplex particles was developed for the rapid detection of biomarkers (16 min). In this device, probe particles attach to capture particles (dp = 40 µm) and form sandwiched immunocomplexes in the presence of target biomarkers, and a red color progressively emerges when the sandwiched immunocomplex particles are blocked by the porous hydrogel embedded inside the glass capillary. Colorimetric aggregation was recorded using a smartphone and analyzed with imaging software. The limit of detection reached 1 ng/mL and showed a maximum of 79% accuracy compared with that obtained through a conventional spectrophotometric technique. The level of a diabetic retinopathy (DR) biomarker, lipocalin-1 (LCN-1), was measured in 1 µL of a human tear sample and used in testing the practicability of the proposed device. All healthy subjects showed lower intensity levels than the other diabetic counterparts (proliferative DR or nonproliferative DR patients), implying the potential of this device in clinical applications. Overall, the diagnostic device facilitates point-of-care-testing and provides a low-cost (~1 USD), compact, and reliable tool for early diagnosis in resource-limited areas.

Polystyrene nanospheres (PNs) were embedded in bovine skin gelatin gels with a poly(N-isopropylacrylamide) (PNIPAAm) network, which were denoted as NGHHs, to generate thermoresponsive behavior. When 265 nm PNs were exploited to generate the pores, bovine skin gelatin extended to completely occupy the pores left by PNs below the lower critical solution temperature (LCST), forming a pore-less structure. Contrarily, above the LCST, the collapse of hydrogen bonding between bovine skin gelatin and PNIPAAm occurred, resulting in pores in the NGHH. The behavior of pore closing and opening below and above the LCST, respectively, indicates the excellent drug gating efficiency. Amoxicillin (AMX) was loaded into the NGHHs as smart antibiotic gating due to the pore closing and opening behavior. Accordingly, E. coli. and S. aureus were exploited to test the bacteria inhibition ratio (BIR) of the AMX-loaded NGHHs. BIRs of NGHH without pores were 48% to 46.7% at 25 and 37 °C, respectively, for E. coli during 12 h of incubation time. The BIRs of nanoporous NGHH could be enhanced from 61.5% to 90.4% providing a smart antibiotic gate of bovine skin gelatin gels against inflammation from infection or injury inflammation.

In this article, we present a semi-interpenetrating network (IPN) hydrogel of reasonable size with improved swelling behavior. The semi-IPN is composed of N-isopropylacrylamide and 2-acrylamido-2-methyl-1-propanesulfonic acid. Porosity was generated chemically by a surfactant-based template method. The swelling behavior was measured after an abrupt change of the temperature to 25 °C or 40 °C or after an abrupt change of the salt concentration of the aqueous medium surrounding the hydrogel samples. A set of static swelling degrees was determined from swelling measurements in salt solutions of varying concentrations and at different temperatures. Introducing porosity to the semi-IPN decreases the swelling times for most measurements while the sensor and actuator characteristics of the hydrogel found in previous studies are preserved. Additionally, we propose theoretical assumptions and explanations regarding the differences in the swelling kinetics of the porous and the nonporous semi-IPN and deduce implications for sensor and actuator applications.

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, a novel microcapsule was generated by the encapsulation of Lactobacillus acidophilus using konjac glucomannan (KGM) hydrogel. Micropowder of L. acidophilus was mixed with gel particles, which was encapsulated in a microcapsule wall material produced by the combination of konjac oligosaccharides (KO) and sodium alginate (SA). The encapsulation and stability (both storage and digested) along with the microstructure of the capsules were analysed by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The results revealed that the microencapsulation rate was 62.5%, Dialdehyde glucomannan (DAK)/gelatin crosslinked gel formed numerous interconnected pores, and the pore wall was thick and smooth, which could well protect the microorganisms inside. Study of the storage stability showed that microencapsulated L. acidophilus could be stored for longer at both 4 °C and 25 °C. Gastric fluid simulation results confirmed that microencapsulation improved the acid resistance of L. acidophilus . An enteric test revealed that the number of viable bacteria increased with an extension of the digestion time, and no solid particles were observed in the solution after 45 min. In addition, KO was applied as both prebiotic of L. acidophilus and anti-freeze agent. It is illustrated that the survival rates of L. acidophilus (with and without encapsulated) were significantly increased during freeze drying situation. This work contributes a pathway on the construction of advanced L. acidophilus microcapsules by using KGM as a main precursor. [ABSTRACT FROM AUTHOR]

The aim of this research was to prepare a novel sponge-like porous hydrogel scaffold based on human-like collagen (HLC) that could be applied in cartilage tissue regeneration. In this study, bovine serum albumin (BSA) was used as a porogen to prepare the porous hydrogel, which had not been previously reported. Glutamine transaminase (TGase) was used as the cross-linker of the hydrogel, because it could catalyze the cross-linking of BSA. During the crosslinking process, BSA and HLC were mixed together, which affected the cross-linking of HLC. When the cross-linking was completed, the non-crosslinked section formed pores. The microstructure, porosity, swelling properties, and compressive properties of the hydrogel were studied. The results showed that the pore size of the hydrogel was between 100 and 300 m, the porosity reached up to 93.43%, and the hydrogel had rapid water absorption and suitable mechanical properties. Finally, we applied the hydrogel to cartilage tissue engineering through in vitro and in vivo research. The in vitro cell experiments suggested that the hydrogel could promote the proliferation and adhesion of chondrocytes, and in vivo transplantation of the hydrogel could enhance the repair of cartilage. In general, the hydrogel is promising as a tissue engineering scaffold for cartilage. [ABSTRACT FROM AUTHOR]

Hydrogel-based adsorbents have good application prospects in wastewater treatment, but their low porosity and specific surface area pose challenges to their practical applications. In this study, a porous hydrogel (T-PMADA) was prepared by copolymerization of acrylic acid (AA) and methacrylamide dopamine (MADA) in the presence of Ti 3 C 2 MXene. The porous structure not only increased the specific surface area (44.2 m2/g) of the hydrogel, but also provided abundant active sites for the treatment of the pollutant, which led to the maximum adsorption capacity of T-PMADA hydrogel for Pb (II) and Cd (II) of 609.9 mg/g and 250.2 mg/g, respectively. In addition, the TiO 2 @C formed by the oxidation of Ti 3 C 2 MXene also endows the hydrogel with the photocatalytic degradation ability for organic dyes. In treating the wastewater containing heavy metal ions and organic dyes, the T-PMADA hydrogel shows good treatment performance for heavy metal ions and organic dyes simultaneously. The above facts indicate that T-PMADA hydrogel can provide a brand-new strategy for water pollution treatment in complex polluted environments by its ability to treat heavy metals and organic dye pollutants. • The porous hydrogel was synthesized by co -polymerizate of AA and MADA. • The porous structure enhanced the adsorption efficiency of the hydrogel. • The TiO 2 /C formed by the oxidation of Ti 3 C 2 MXene endows the hydrogel with photocatalytic properties. [ABSTRACT FROM AUTHOR]

Formulation of multifunctional biopolymer-based scaffolds is one of the major focuses in modern tissue engineering and regenerative medicine. Besides proper mechanical/chemical properties, an ideal scaffold should: (i) possess a well-tuned porous internal structure for cell seeding/growth and (ii) host bioactive molecules to be protected against biodegradation and presented to cells when required. Alginate hydrogels were extensively developed to serve as scaffolds, and recent advances in the hydrogel formulation demonstrate their applicability as “ideal” soft scaffolds. This review focuses on advanced porous alginate scaffolds (PAS) fabricated using hard templating on vaterite CaCO3 crystals. These novel tailor-made soft structures can be prepared at physiologically relevant conditions offering a high level of control over their internal structure and high performance for loading/release of bioactive macromolecules. The novel approach to assemble PAS is compared with traditional methods used for fabrication of porous alginate hydrogels. Finally, future perspectives and applications of PAS for advanced cell culture, tissue engineering, and drug testing are discussed.

The tremendous reinforcing and pore-stabilizing effect of in situ formed nanosilica in a highly porous temperature-responsive poly(N-isopropylacrylamide) (PNIPA) matrix is demonstrated. A veryweakly crosslinked semi-liquid hydrogel can be reinforced to the point that it displays a fast, extensive and nearly symmetric temperature-responsiveness in combination with an acceptable modulus. In soft but solid porous PNIPA, only 0.6wt% of the nanofiller is sufficient to stabilize the pores against collapse upon de-swelling, thus enabling ultrafast responsiveness. A spectacular effect is achieved with dried porous PNIPA (matrix is glassy, Tg ≈140 °C), which in the case of optimal nanosilica amounts can re-swell in only 3min. The key importance of efficient hydrogen bridging between PNIPA and SiO2 is demonstrated by comparing in situ formed nanosilica with similarly sized commercial Ludox particles, the surface of which is saturated with ammonia (for stabilization). Synthesis parameters like the amount of crosslinker and of nanosilica were varied in a wide range, in order to achieve the fastest possible responsiveness of the hydrogels in combination with a high modulus. The porosity, nanosilica distribution, moduli, temperature-dependent swelling as well as the swelling kinetics of the gels were determined as functions of contents of crosslinker and nanosilica. [ABSTRACT FROM AUTHOR]

In this study, the reinforcing effects of cellulose nanofibrils (CNFs) on poly (vinyl alcohol) (PVA) matrix were explored. And ethylene glycol was used to enhance the water content and phosphate buffer saline (PBS) absorbency. The morphological aspects of the hydrogel were studied by transmission electron microscope (TEM) and scanning electron microscopy (SEM). The presence of interactions, changes in crystallinity as well as thermal behaviour were investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermogravimetry respectively. With the increase of CNFs concentration, the composite greatly improved its mechanical strength while maintaining remarkable ductility through tensile test results. The positive results of cell toxicity test suggested our porous hydrogel could provide ideal cell growth environment. This work revealed that CNFs hydrolysed by bacterial cellulose could perform as a perfect reinforcing agents which is of great interest in the fields of biotechnology and biomedicine with the potential values in cell culture, co-cultivation, as well as biomedical scaffold materials. [ABSTRACT FROM AUTHOR]