Hydrogel Template Research Articles

Temperature-responsive two-dimensional polydopamine hydrogel: Preparation, mechanisms, and applications in cancer treatment

Temperature-responsive hydrogels are advanced materials that exhibit significant physical or chemical changes in response to temperature variations. When the temperature reaches a specific threshold, these hydrogels alter their properties accordingly. They offer significant advantages in cancer therapy, including precise control over drug release, minimized toxicity, improved therapeutic efficacy, and biodegradability. Advancing the development of novel temperature-responsive hydrogels is crucial for enhancing therapeutic strategies. Herein, two-dimensional polydopamine (2D PDA) was first combined with chitosan (CTS) to create a temperature-responsive hydrogel for the control and release of anticancer drugs. Leveraging the carbonyl-rich nature of 2D PDA, we initiated a reversible cyclization reaction between CTS and the carbonyl groups on the surface of 2D PDA, resulting in a temperature-responsive CTS@2D PDA (CP) hydrogel. Furthermore, the CP hydrogel template was incorporated with the photosensitizer zinc phthalocyanine (ZnPc) and sodium percarbonate (SPC), an oxygen (O2) donor, to form a composite hydrogel (CSZP hydrogel). O2 released from the CSZP hydrogel mitigated solid tumor hypoxia and suppressed the expression of hypoxia-inducible factor-1α (HIF-1α), thereby augmenting the efficacy of photodynamic therapy (PDT). This temperature-responsive hydrogel represented a highly promising platform for the precise and controlled release of various therapeutics, thereby advancing the field of targeted disease treatment.

Facile One-Pot Preparation of Polypyrrole-Incorporated Conductive Hydrogels for Human Motion Sensing.

Conductive hydrogels have been widely used in soft robotics, as well as skin-attached and implantable bioelectronic devices. Among the candidates of conductive fillers, conductive polymers have become popular due to their intrinsic conductivity, high biocompatibility, and mechanical flexibility. However, it is still a challenge to construct conductive polymer-incorporated hydrogels with a good performance using a facile method. Herein, we present a simple method for the one-pot preparation of conductive polymer-incorporated hydrogels involving rapid photocuring of the hydrogel template followed by slow in situ polymerization of pyrrole. Due to the use of a milder oxidant, hydrogen peroxide, for polypyrrole synthesis, the photocuring of the hydrogel template and the growing of polypyrrole proceeded in an orderly manner, making it possible to prepare conductive polymer-incorporated hydrogels in one pot. The preparation process is facile and extensible. Moreover, the obtained hydrogels exhibit a series of properties suitable for biomedical strain sensors, including good conductivity (2.49 mS/cm), high stretchability (>200%), and a low Young's modulus (~30 kPa) that is compatible with human skin.

Superhydrophobic cement with hierarchically tunable pore structure by additive manufacturing towards super sound absorption

Noise pollution as a form of environmental problem can have significant negative impacts on human health and the economy. To address this issue, a variety of noise-reduction construction materials have been developed. However, most present noise reduction materials suffer from a narrow absorbing band due to the simple pore structure which restricts their ability to absorb sound energy across a wide frequency range. Here, we demonstrate a hydrogel templating method and create hierarchically structured cement-based materials with tunable pore sizes by means of additive manufacturing. The introduction of this hierarchically tunable structure with micro-nano pores generated by cement hydration contributes to the formation of multi-scale pores (micro-, meso- and macropores), which achieves a sound absorption coefficient of 0.89 at 1000 Hz and ensures broadband acoustic absorption performance (noise reduction coefficient of 0.54, around 50 % improvement compared to traditional construction sound absorption materials). Meantime, this lightweight material has good compressive strength (1.31 MPa) and superhydrophobicity (water contact angle of 152.5°), together with thermal conductivity (0.088 W m−1 K−1) and excellent fire resistance. This study provides a new approach for designing cement-based materials with super sound absorption.

Efficient chiral hydrogel template based on supramolecular self-assembly driven by chiral carbon dots for circularly polarized luminescence

Since the chiral emission of excited states is observed on carbon dots (CDs), exploration towards the design and synthesis of chiral CDs nanomaterials with circularly polarized luminescence (CPL) properties has been at a brisk pace. In this regard, the “host and guest” co-assembly strategy based on the combination of CDs and chiral templates has been of unique interest recently for its convenient operation, multicolor tunable CPL, and wide application of prepared CDs-composited materials in optoelectronic devices and information encryption. However, the existing chiral templates that match perfectly with chiral CDs exhibiting optical activity both in ground and excited states are rather scarce. In this work, we synthesize the chiral CDs that could induce the spontaneous supramolecular self-assembly of N-(9-fluorenylmethox-ycarbonyl) (Fmoc)-protected glutamic acid to form chiral hydrogels with helical nanostructure. The co-assembled hydrogels show powerful chiral template function, which not only enable chiral CDs with a luminescence dissymmetry factor (glum) up to 10-2, but also have universal chiral transfer to inserted dye molecules, realizing full-color CPL and Förster resonance energy transfer (FRET) CPL as well as the distinction between left and right circularly polarized light. This CPL-active template based on chiral CDs enriches the design scenario of chiral functionalized nanomaterials.

Preparation of PPA based composite reinforcing with glass beads and clays: Investigation of sound absorbing

The research investigates the sound absorption properties of potassium polyacrylate (PPA) composites, particularly those augmented with clay and porous hollow glass beads within a hydrogel template. This unique material combination shows promise for efficient sound absorption, relevant in industries requiring effective noise control like acoustic engineering and construction. Experimental assessment focused on measuring the sound absorption coefficient, crucial for quantifying a material’s ability to absorb sound energy across various frequencies. Incorporating clay and porous hollow glass beads introduces complexities, emphasizing the need for precise acoustic performance prediction. Collected data from sound absorption coefficient measurements formed the basis for training an Artificial Neural Network (ANN) model. Leveraging the ANN’s pattern recognition capabilities, the model learned from diverse composite compositions, enabling accurate prediction of sound absorption coefficients for varying material compositions. This predictive model streamlines material design, offering a systematic approach to tailor composite acoustic characteristics. Integration of machine learning, particularly ANNs, enhances accuracy and expedites material design and optimization, contributing to innovative and customizable sound-absorbing materials for diverse industrial applications.

Engineered Living Structures with Shape-Morphing Capability Enabled by 4D Printing with Functional Bacteria.

Engineered living structures with the incorporation of functional bacteria have been explored extensively in recent years and have shown promising potential applications in biosensing, environmental remediation, and biomedicine. However, it is still rare and challenging to achieve multifunctional capabilities such as material production, shape transformation, and sensing in a single-engineered living structure. In this study, we demonstrate bifunctional living structures by synergistically integrating cellulose-generating bacteria with pH-responsive hydrogels, and the entire structures can be precisely fabricated by three-dimensional (3D) printing. Such 3D-printed bifunctional living structures produce cellulose nanofibers in ambient conditions and have reversible and controlled shape-morphing properties (usually referred to as four-dimensional printing). Those functionalities make them biomimetic versions of silkworms in the sense that both can generate nanofibers and have body motion. We systematically investigate the processing-structure-property relationship of the bifunctional living structures. The on-demand separation of 3D cellulose structures from the hydrogel template and the living nature of the bacteria after processing and shape transformation are also demonstrated.

Highly efficient sorbent utilizing regenerated cellulose as an eco-friendly template for humic acid removal and oil–water separation processes

In this study, a novel and environmentally friendly sorbent was developed utilizing regenerated cellulose (RC) as a renewable resource. The preparation process of the regenerated cellulose hydrogel, following a bottom-up strategy, occurs in an aqueous system and offers the added benefits of temperature-induced gelation and solvent recyclability. The RC/PEI aerogel was prepared through a polyethyleneimine (PEI) modification and di-epoxide crosslinking process, which improves the gel's elastic recovery for the squeezing process and concurrently provides excellent ability to remove humic acid (HA) contaminants. As a result of the HA removal experiment using the RC/PEI aerogel in an aqueous environment, the gel showed an experimental HA adsorption capacity of 124.9 mg/g and qm value of 196.7 mg/g. Furthermore, the prepared RC hydrogel template was successfully transformed into a highly effective oil–water separation sorbent through a hydrophobic alkylated graphene oxide (AGO) coating process. Oil-water separation was carried out using AGO-RC/PEI gel, and it was possible to successfully adsorb the oil and then recover it through the squeezing process. In addition, long-term usability has been validated by demonstrating an oil adsorption capacity of over 84 %, even after ten consecutive reuses.

Chitosan-Polyethylene Glycol Inspired Polyelectrolyte Complex Hydrogel Templates Favoring NEO-Tissue Formation for Cardiac Tissue Engineering.

Neo-tissue formation and host tissue regeneration determine the success of cardiac tissue engineering where functional hydrogel scaffolds act as cardiac (extracellular matrix) ECM mimic. Translationally, the hydrogel templates promoting neo-cardiac tissue formation are currently limited; however, they are highly demanding in cardiac tissue engineering. The current study focused on the development of a panel of four chitosan-based polyelectrolyte hydrogels as cardiac scaffolds facilitating neo-cardiac tissue formation to promote cardiac regeneration. Chitosan-PEG (CP), gelatin-chitosan-PEG (GCP), hyaluronic acid-chitosan-PEG (HACP), and combined CP (CoCP) polyelectrolyte hydrogels were engineered by solvent casting and assessed for physiochemical, thermal, electrical, biodegradable, mechanical, and biological properties. The CP, GCP, HACP, and CoCP hydrogels exhibited excellent porosity (4.24 ± 0.18, 13.089 ± 1.13, 12.53 ± 1.30 and 15.88 ± 1.10 for CP, GCP, HACP and CoCP, respectively), water profile, mechanical strength, and amphiphilicity suitable for cardiac tissue engineering. The hydrogels were hemocompatible as evident from the negligible hemolysis and RBC aggregation and increased adsorption of plasma albumin. The hydrogels were cytocompatible as evident from the increased viability by MTT (>94% for all the four hydrogels) assay and direct contact assay. Also, the hydrogels supported the adhesion, growth, spreading, and proliferation of H9c2 cells as unveiled by rhodamine staining. The hydrogels promoted neo-tissue formation that was proven using rat and swine myocardial tissue explant culture. Compared to GCP and CoCP, CP and HACP were superior owing to the cell viability, hemocompatibility, and conductance, resulting in the highest degree of cytoskeletal organization and neo-tissue formation. The physiochemical and biological performance of these hydrogels supported neo-cardiac tissue formation. Overall, the CP, GCP, HACP, and CoCP hydrogel systems promise novel translational opportunities in regenerative cardiology.

Guanosine-based hydrogel as a supramolecular scaffold for template-assisted macrocyclization.

The G-quartet-like supramolecular assembly present in guanosine hydrogel templates macrocyclization between bis-azide and bis-alkyne fragments. The resulting macrocycle enhances viscoelastic properties, and strengthens the hydrogel network. This approach holds potential for the in situ synthesis of drugs and their simultaneous delivery in a stimuli-responsive manner.

Nucleation-Supersaturation Dual-Drive Crystallization Strategy Enables Efficient Protein Crystallization.

A rational crystallization strategy is essential to obtain high-quality protein crystals, yet the established methods suffer from different limitations arising from the single regulation on either nucleation or supersaturation. Herein, a nucleation-supersaturation dual-driven crystallization (DDC) strategy that realizes synergistic regulation of heterogeneous nucleation sites and solution supersaturation based on dual surface and confinement effects for efficient protein crystallization is reported. This strategy relies on a p(PEGDA-co-DMAA) hydrogel template with pre-filled NaCl under designed concentrations. Once dropping hen egg white lysozyme (HEWL) protein solution on the hydrogel, the wrinkled surface provides numerous nucleation sites, while the internal structure regulates the solution supersaturation in the crystallization region through diffusion. Finally, DDC strategy can create high-quality HEWL crystals with large sizes (100-300µm), well-defined morphologies (hexagon and tetragon), and a significantly accelerated nucleation time (9-12 times faster than that achieved using the conventional hanging drop method). It also performs well at wider protein concentrations (10-50mgmL-1) and categories (e.g., achieving fast crystallization and large-size crystals of trypsin), therefore demonstrating clear advantages and great potential for efficiently fabricating protein crystals desirable for diverse applications.

Porous biochars with nitrogen defects prepared from hydrogel template-modified food waste for high-performance supercapacitors

The complex composition and heterogeneous nature of food waste limit the application of biochar materials derived from it in supercapacitors. In this study, biochar was prepared from simulated food waste using a hydrogel template and employed to fabricate supercapacitor electrodes. Food waste was first transformed into a soluble state through an advanced oxidation process (potassium persulfate/heat). Small-molecule polymerization was then performed to generate a structurally uniform food waste hydrogel (FWH). Urea was added during the synthesis of FWH to achieve the uniform incorporation of nitrogen into its structure. FWH biochar (FWHB) was obtained from FWH via pyrolysis at different temperatures (500, 700, and 900 °C). Then, we evaluated the physicochemical properties and electrochemical performances of the obtained FWHB samples. The FWHB pyrolyzed at 700 °C (FWHB700) exhibited a unique sponge-like microstructure with a high specific surface area of 693 m2∙g−1, which was 20 times that of untreated food waste biochar. FWHB700 also showed excellent energy storage performance, with a specific capacitance of up to 461 F∙g−1 at a current density of 1 A∙g−1. Based on physicochemical analysis and density functional theory calculations, the energy storage capacity of FWHB700 was found to be related to its high specific surface area, developed pore structure, as well as abundant nitrogen defects and heteroatom active sites. The symmetric FWHB700//FWHB700 supercapacitor delivered a high energy density of 9.99 Wh∙kg−1 at a power density of 125 W∙kg−1, with 88.2 % capacitance retention after 10,000 charge–discharge cycles. In summary, this study introduces a promising electrode material for energy storage and provides a new approach for the efficient utilization of food waste resources.

Templated Reactive Crystallization of Active Pharmaceutical Ingredient in Hydrogel Microparticles Enabling Robust Drug Product Processing

Commercialization of most promising active pharmaceutical ingredients (APIs) is impeded either by poor bioavailability or challenging physical properties leading to costly manufacture. Bioavailability of ionizable hydrophobic APIs can be enhanced by its conversion to salt form. While salt form of the API presents higher solution concentration than the non-ionized form, poor physical properties resulting from particle anisotropy or non-ideal morphology (needles) and particle size distribution not meeting dissolution rate targets can still inhibit its commercial translation. In this regard, API physical properties can be improved through addition of non-active components (excipients or carriers) during API manufacture. In this work, a facile method to perform reactive crystallization of an API salt in presence of the microporous environment of a hydrogel microparticle is presented. Specifically, the reaction between acidic antiretroviral API, raltegravir and base potassium hydroxide is performed in the presence of polyethylene glycol diacrylamide hydrogel microparticles. In this bottom-up approach, the spherical template hydrogel microparticles for the reaction lead to monodisperse composites loaded with inherently micronized raltegravir-potassium crystals, thus improving API physical properties without hampering bioavailability. Overall, this technique provides a novel approach to reactive crystallization while maintaining the API polymorph and crystallinity.

Preparation of Coupling Catalyst HamZIF-90@Pd@CALB with Tunable Hollow Structure for Efficient Dynamic Kinetic Resolution of 1-Phenylethylamine.

Chiral amines are essential components for many pharmaceuticals and agrochemicals. However, the difficulty in obtaining enantiomerically pure amines limits their application. In this study, hollow amorphous ZIF-90 (HamZIF-90) materials were prepared by template engraving, and chemical-enzyme coupling catalysts (HamZIF-90@Pd@CALB) were constructed for the chiral resolution of 1-phenylethylamine. Different from conventional materials, HamZIF-90 had tunable hollow structures by altering its central node zinc ion concentrations, and the embedded hydrogel template gave it more pore structures, which facilitated the loading of enzyme molecules and Pd nanoparticles (NPs). The establishment of the coupling catalysts shortened the mass transfer distance of the reactant molecules between the metal nanoparticles and the enzyme catalyst in the dynamic kinetic resolution (DKR) reaction, resulting in 98% conversion of 1-phenylethylamine and 93% selectivity of Sel.R-amide. The proposal of this idea provided a good idea for future tailor-made MOFs loaded with chemical and enzyme coupled catalyst.

Carboxymethyl cellulose-alginate interpenetrating hydroxy ethyl methacrylate crosslinked polyvinyl alcohol reinforced hybrid hydrogel templates with improved biological performance for cardiac tissue engineering.

Cardiac tissue engineering is an emerging approach for cardiac regeneration utilizing the inherent healing responses elicited by the surviving heart using biomaterial templates. In this study, we aimed to develop hydrogel scaffolds for cardiac tissue regeneration following myocardial infarction (MI). Two superabsorbent hydrogels, CAHA2A and CAHA2AP, were developed employing interpenetration chemistry. CAHA2A was constituted with alginate, carboxymethyl cellulose, (hydroxyethyl) methacrylate, and acrylic acid, where CAHA2AP was prepared by interpenetrated CAHA2A with polyvinyl alcohol. Both hydrogels displayed superior physiochemical characteristics, as determined by attenuated total reflection infrared spectroscopy spectral analysis, differential scanning calorimetrymeasurements, tensile testing, contact angle, water profiling, dye release, and conductivity. In vitro degradation of the hydrogels displayed acceptable weight composure and pH changes. Both hydrogels were hemocompatible, and biocompatible as evidenced by direct contact and MTT assays. The hydrogels promoted anterograde and retrograde migration as determined by the z-stack analysis using H9c2 cells grown with both gels. Additionally, the coculture of the hydrogels with swine epicardial adipose tissue cells and cardiac fibroblasts resulted in synchronous growth without any toxicity. Also, both hydrogels facilitated the production of extracellular matrix by the H9c2 cells. Overall, the findings support an appreciable in vitro performance of both hydrogels for cardiac tissue engineering applications.

Controllable synthesis of Mn3O4 nanoparticles through in situ reduction reaction via PVA hydrogel template for Fenton-like degradation

Controllable synthesis of Mn3O4 nanoparticles through in situ reduction reaction via PVA hydrogel template for Fenton-like degradation

Regeneration of critical-sized grade II furcation using a novel injectable melatonin-loaded scaffold.

Periodontal regenerative therapy using bone-substituting materials has gained favorable clinical significance in enhancing osseous regeneration. These materials should be biocompatible, osteogenic, malleable, and biodegradable. This study assessed the periodontal regenerative capacity of a novel biodegradable bioactive hydrogel template of organic-inorganic composite loaded with melatonin. A melatonin-loaded alginate-chitosan/beta-tricalcium phosphate composite hydrogel was successfully prepared and characterized. Thirty-six critical-sized bilateral class II furcation defects were created in six Mongrel dogs, and were randomly divided and allocated to three cohorts; sham, unloaded composite, and melatonin-loaded. Periodontal regenerative capacity was evaluated via histologic and histomorphometric analysis. Melatonin-treated group showed accelerated bone formation and advanced maturity, with a significant twofold increase in newly formed inter-radicular bone compared with the unloaded composite. The short-term regenerative efficacy was evident 4 weeks postoperatively as a significant increase in cementum length concurrent with reduction of entrapped epithelium. After 8 weeks, the scaffold produced a quality of newly synthesized bone similar to normal compact bone, with potent periodontal ligament attachment. Melatonin-loaded hydrogel template accelerated formation and enhanced quality of newly formed bone, allowing complete periodontal regeneration. Furthermore, the scaffold prevented overgrowth and entrapment of epithelial cells in furcation defects.

Strychnos Potatorum L. Seed Polysaccharide-Based Stimuli-Responsive Hydrogels and Their Silver Nanocomposites for the Controlled Release of Chemotherapeutics and Antimicrobial Applications.

Natural Strychnos potatorumL. (SPL) polysaccharide-based dual-responsive semi-IPN-type (SPL-DMA) hydrogels have been fabricated using dimethylaminoethyl methacrylate by simple free radical polymerization. Furthermore, a facial and eco-friendly method has been developed for the green synthesis of silver nanoparticles on SPL-DMA hydrogel templates (SPL-DMA-Ag) using an aqueous leaf extract of Carissa spinarum (as a bioreducing agent). SPL-DMA and SPL-DMA-Ag were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and evaluated network parameters. 5-Fluorouracil and doxorubicin were successfully encapsulated, and in vitro drug release studies were performed at pH values of 1.2 and 7.4 and at 25 and 37 °C. To understand the drug release mechanism of SPL-DMA hydrogels, various kinetic parameters were calculated. Biocompatibility and anticancer activities of SPL-DMA hydrogels were proved by an antioxidant activity study and in vitro cell viability studies against HeLa and 3T3-L1 cell lines. SPL-DMA-Ag hydrogels were used for antibacterial application.

Growing Hydrogel Organ Mannequins with Interconnected Cavity Structures

AbstractBiomimicking organ mannequins with not only lifelike biological geometries but also virtually constituting connected circulation channels for exchanging substances are critical for in vitro biomedical applications, yet the big challenges remain. This paper reports a big step toward the goal to achieve hydrogel‐based organ mannequins with internal channels and a cavity, gradient structures, and a physiological environment of organs for in vitro purposes via metal ions‐induced interface supramolecular assembly of hydrogel layers on the thermally splitting templates. The templates composed of gelatin and ι‐carrageenan are built through direct ink writing, which are employed as the supports to in situ grow the alginate/Ca2+ hydrogel layers by rapid diffusion‐induced gelation process. Removing the hydrogel templates based on sol–gel conversion can readily yield hydrogel architectures with connected channels, structural integrity, and favorable physicochemical properties. Proof‐of‐concept hydrogel mannequins including the branched vascular replicas, digestive system, distal lung subunit, and glomerulus with mechanical robustness are engineered from replicating the tubular structure to imitate the basic profiles of organs. It is believed that this protocol paves a versatile way to construct hydrogel‐based biomimicking mannequins with cavity structures that can be used for in vitro biomedical training, testing, pharmacology, etc.

MoS2 QDs/8-Armed Poly(Ethylene Glycol) Fluorescence Sensor for Three Nitrotoluenes (TNT) Detection.

In this work, ammonia cross-linked 8-armed polyethylene glycol hydrogel material was successfully synthesized and used as a template for synthesizing nanoparticles with fluorescent properties. The 8-armed polyethylene glycol hydrogel template was used to prepare molybdenum disulfide quantum dots (MoS2 QDs). The ammonium tetrathiomolybdate functioned as a molybdenum source and hydrazine hydrate functioned as a reducing agent. The fluorescence properties of the as-prepared MoS2 QDs were investigated. The bursting of fluorescence caused by adding different concentrations of explosive TNT was studied. The study indicated that the synthesized MoS2 QDs can be used for trace TNT detection with a detection limit of 6 nmol/L and a detection range of 16–700 nmol/L. Furthermore, it indicated that the fluorescence-bursting mechanism is static bursting.

High‐performance adsorptive desulfurization by ternary hybrid boron carbon nitride aerogel

AbstractSeparation of aromatic organosulfur compounds is vital for upgrading the feed to clean fuel products, however, it remains a formidable challenge for the present adsorbents. Herein, a series of novel aerogel‐like boron carbon nitride (BCN) with three‐dimensional interconnected porous networks were fabricated via a hydrogel template and freeze‐casting strategy. The as‐prepared aerogel‐like BCN had a variable carbon content and a flexible size of graphene domain on its porous structure. The optimal BCN aerogel represents the top‐level of adsorptive desulfurization (ADS) capacity for aromatic organosulfur compounds (30.8 mg S/g adsorbent), strikingly higher than the state‐of‐the‐art aerogels adsorbents (17.1 mg S/g adsorbent) reported under similar conditions. A selective adsorption for dibenzothiophene in the presence of aromatic hydrocarbons, nitrogen compounds were also achieved on BCN aerogel. The adsorption isotherm and XPS measurement reveal heterogeneous adsorption on the BCN aerogel via π–π and Lewis acid–base interactions.