Monolithic Hydrogel Research Articles

Hybrid chitosan/HKUST-1 hydrogel with freezing and thawing modification as sustainable porous material for removal and selective separation of dye mixtures

A hybrid chitosan monolithic hydrogel (CS) was modified by incorporating with HKUST-1 and fabricated using an in-situ growth method. The resulting hydrogel CS/HKUST-1 was further modified to enhance the porous structure, in which the porous converted from close pores to interconnected porous structures. The chemical and physical characteristics of the modified hydrogel were examined using various characterization techniques like BET, SEM, EDX, FTIR, XRD, Zeta potential, and compression test to understand the effect of the modification. The outcomes displayed that this method provided homogeneous dispersing of HKUST-1 crystals within the chitosan hydrogel matrix, which can improve the material's specific surface area and adsorption capacity. The CS/HKUST-1 monolithic hybrid hydrogel's permeability is further enhanced by the freezing and thawing process and the produced hydrogel is called FCS/HKUST-1, which helps to open the hydrogel's pores and significantly increases its surface area. FCS/HKUST-1 hydrogels display higher mechanical properties without fracture after compression with elastic properties, whereas the CS/HKUST-1 hydrogel crashed at around 47 % compression strain. Consequently, the obtaining dual modified chitosan/ HKUST-1 hydrogel (FCS/HKUST-1) was evaluated as an adsorbent to eliminate Eosin Y (EY) dye from its aqueous solution and the adsorption mechanism was proposed as multilayer adsorption depending on the Freundlich isotherm model. The modified monolithic hydrogel displayed an excellent maximum adsorption capacity with EY dye about 625 mg·g−1. The FCS/HKUST-1 hydrogel showed extremely selective removal for anionic dye higher than cationic dye, which allows facile separation of the dyes with different charges in a mixture solution. The outcomes also demonstrate that the modified hydrogel would be an eco-friendly material, which shows excellent recyclability, indicating that this material considerable promising adsorbent in water treatment.

Design approaches for 3D cell culture and 3D bioprinting platforms.

The natural habitat of most cells consists of complex and disordered 3D microenvironments with spatiotemporally dynamic material properties. However, prevalent methods of in vitro culture study cells under poorly biomimetic 2D confinement or homogeneous conditions that often neglect critical topographical cues and mechanical stimuli. It has also become increasingly apparent that cells in a 3D conformation exhibit dramatically altered morphological and phenotypical states. In response, efforts toward designing biomaterial platforms for 3D cell culture have taken centerstage over the past few decades. Herein, we present a broad overview of biomaterials for 3D cell culture and 3D bioprinting, spanning both monolithic and granular systems. We first critically evaluate conventional monolithic hydrogel networks, with an emphasis on specific experimental requirements. Building on this, we document the recent emergence of microgel-based 3D growth media as a promising biomaterial platform enabling interrogation of cells within porous and granular scaffolds. We also explore how jammed microgel systems have been leveraged to spatially design and manipulate cellular structures using 3D bioprinting. The advent of these techniques heralds an unprecedented ability to experimentally model complex physiological niches, with important implications for tissue bioengineering and biomedical applications.

Ice-template freeze-casting synthesis of polysilsesquioxane aerogel long fibers for broadband sound absorption

Aerogel fibers inherit the merits of aerogel and fibrous materials, such as ultralow density, large specific surface area and high flexibility, demonstrating great potential as the next generation functional fibers. Herein, an ice-template freeze-casting strategy is developed to prepare polysilsesquioxane aerogel long fibers (PALFs) similar to natural fibers in structure. During the freeze-casting, the strong mutual interaction between solid and liquid phases in the hydrogel induces uniform nucleation and continuous growth of ice crystals in confined spaces. The three-dimensional monolithic hydrogel is gradually deconstructed into one-dimensional fibrous geometries by the growing columnar ice crystals. The obtained PALFs exhibit the polygonal cross-section with a uniform mesoporous structure. After simple physical assembly, the monolithic PALFs exhibit good thermal insulation performance (as low as 25.0 mW/(m·K) at 25 °C) and high-efficiency absorption of broadband sound waves (with a noise reduction coefficient up to 0.58).

The Thermophysical Aspects of the Transformation of Porous Structures in Versatile Nanostructured Materials

The technology of obtaining porous nanostructures is based on ecological organosilicon materials and their uses in some spheres of human life, for example, for medical preparations, for thermal insulation of building structures and industrial equipment, and for cleaning. The purpose of this study was to establish correlations between various experimental parameters (shear stress, speed pulsations, temperature, viscosity, and processing time) and the rheological characteristics of suspensions obtained by the method of liquid-phase dispersion; it was a study of hydrodynamic effects and the processes of heat and mass exchange in liquid systems during the liquid-phase dispersion of hydrogel monoliths by means of discrete-pulse activation in a special rotary apparatus. The dehydration of hydrogels was carried out by two methods: convective drying in a layer and spraying in the coolant flow. Experiments have shown that the key parameters for obtaining stable homogeneous suspensions are a synergistic combination of concentration factors and processing time. To obtain adsorbents in the form of pastes with specified adsorption properties and a monolith size of up to 300 μm, the optimal parameters were a hydrogel concentration of 70% and a processing time in the double-recirculation mode. Xerogels obtained by convective drying are a polydisperse mixture of strong monoliths and fragile aggregates. In contrast, xerogel monoliths obtained by spray drying show great homogeneity in terms of dispersion and strength characteristics. The rheological parameters of the hydrogel dispersions, which depend on the concentration and hydrodynamic treatment modes, are the dominant factors affecting the moisture extraction during drying. This study marks the first investigation into the resilience of porous organosilicon structures against the influence of intense turbulence fields and mechanical stresses experienced within the rotor apparatus during suspension production.

Self‐Responsive Janus Hydrogel with Alternation of Day and Night for Highly Efficient Solar Evaporation

Solar‐driven interfacial evaporation technology offers a promising method for sustainable freshwater production. Hydrogels have emerged as promising materials for interfacial evaporation, as they possess the capability to activate water molecules and lower the enthalpy required for evaporation. However, monolithic hydrogels fail to meet the diverse water content requirements in different evaporation regions. Herein, a thermoresponsive hydrogel (CSAm) capable of spontaneously forming Janus structures under sunlight illumination is designed. CSAm exhibits reversible solar‐induced wetting transition, enabling efficient evaporation with asymmetric wetting properties during the day and self‐cleaning of salts with hydrophilic wetting properties during the night. This transition of Janus structures allows for the regulation of water content distribution within the evaporator, meeting the diverse water content requirements of different evaporation regions. CSAm is composed of a thermoresponsive polymer, poly(N,N‐diethylacrylamide), and a hydrophilic polymer, polyacrylamide, cross‐linked to form a scaffold structure. The uniform dispersion of photothermal material (CuS) within the gel scaffold is achieved using lignosulfonates. This study investigates the Janus structure characteristics, photo/thermoresponsive properties, salt resistance, and evaporation performance. Under 1 sun illumination (1 kW m−2), CSAm exhibits a high evaporation rate of 2.67 kg m−2 h−1 and demonstrates long‐term stability in seawater desalination.

Sulfonated Hydrogel Formed via CO2-in-Water Emulsion: Potential in Antibiotic Removal.

Herein, a green, carbon dioxide-in-water high-internal-phase emulsion (C/W HIPEs) was developed and stabilized with polyvinyl alcohol (PVA) for the formation of chitosan oligosaccharide/poly(acrylamide-co-sodium 4-styrene sulfonate) [COS/P(AM-co-SSS)] monolithic porous hydrogel. The obtained monolith was characterized via FT-IR and SEM. The SEM patterns depicted that the monoliths were interconnected, the void sizes were 78.5 µm, and the interconnected pore throats were 28 μm approximately. Mechanical measurement results indicated that the maximum compress stress of the monolith could reach 334.4 kPa at 90% strain, and it exhibited good mechanical stability. After 200 cycles of compression, it could still recover its original shape without cracking. The obtained COS-based monolith was selected to remove tetracycline (TC) for evaluating the adsorptive features of the interpenetrating pore-containing monolith. The monolithic COS/P(AM-co-SSS) hydrogel behaved with strong antibiotic adsorption capacity (1600.4 mg/g for TC). The adsorption process agreed well with the pseudo-second-order kinetic and Langmuir isothermal models. In addition, the porous monolith had a strong electrostatic force on TC according to the thermodynamic study. This work provides a green route for the development of novel monolithic hydrogels and highlights its potential application in the treatment of antibiotic-containing wastewater.

Superelastic Cobalt Silicate@Resorcinol Formaldehyde Resin Core-Shell Nanobelt Aerogel Monoliths with Outstanding Fire Retardant and Thermal Insulating Capability.

The practical applications of resorcinol formaldehyde resin (RFR) aerogels are prevented by their poor mechanical properties. Herein, a facile template-directed method is reported to produce macroscopic free-standing cobalt silicate (CS)@RFR core-shell nanobelt aerogels that display superelastic behavior and outstanding thermal insulating and fire-resistant capability. The synthesis relies on the polymerization of RFR on pre-formed CS nanobelts which leads to in situ formation of hydrogel monoliths that can be transformed to corresponding aerogels by a freeze-drying method. The composite nanobelt aerogel can withstand a compressive load of more than 4000 times of its own weight and fully recover after the removal of the weight. It can also sustain 1000 compressive cycles with 6.9% plastic deformation and 91.8% of the maximum stress remaining, with a constant energy loss coefficient as low as 0.16, at the set strain of 30%. The extraordinary mechanical properties are believed to be associated with the structural flexibility of the nanobelts and the RFR-reinforced joints between the crosslinked nanobelts. These inorganic-organic composite aerogels also show good thermal insulation and excellent fire-proof capability. This work provides an effective strategy for fabricating superelastic RFR-based aerogels which show promising applications in fields such as thermal insulation, energy storage, and catalyst support.

High-Throughput Bioprinting of Geometrically-Controlled Pre-Vascularized Injectable Microgels for Accelerated Tissue Regeneration.

Successful integration of cell-laden tissue constructs with host vasculature depends on the presence of functional capillaries to provide oxygen and nutrients to the embedded cells. However, diffusion limitations of cell-laden biomaterials challenge regeneration of large tissue defects that require bulk-delivery of hydrogels and cells. Herein, a strategy to bioprint geometrically controlled, endothelial and stem-cell laden microgels in high-throughput is introduced, allowing these cells to form mature and functional pericyte-supported vascular capillaries in vitro, and then injecting these pre-vascularized constructs minimally invasively in-vivo. It is demonstrated that this approach offers both desired scalability for translational applications as well as unprecedented levels of control over multiple microgel parameters to design spatially-tailored microenvironments for better scaffold functionality and vasculature formation. As a proof-of-concept, the regenerative capacity of the bioprinted pre-vascularized microgels is compared with that of cell-laden monolithic hydrogels of the same cellular and matrix composition in hard-to-heal defects in vivo. The results demonstrate that the bioprinted microgels have faster and higher connective tissue formation, more vessels per area, and widespread presence of functional chimeric (human and murine) vascular capillaries across regenerated sites. The proposed strategy, therefore, addresses a significant issue in regenerative medicine, demonstrating a superior potential to facilitate translational regenerative efforts.

Three-dimensional printing of soft hydrogel electronics

Electronics based on hydrogels can have inherent similarities to biological tissue and are of potential use in biomedical applications. Ideally, such hydrogel electronics should offer customizable three-dimensional circuits, but making complex three-dimensional circuits encapsulated within a hydrogel matrix is challenging with existing materials and manufacturing methods. Here we report the three-dimensional printing of hydrogel electronics using a curable hydrogel-based supporting matrix and a stretchable silver–hydrogel ink. The supporting matrix has a yield stress fluid behaviour, so the shear force generated by a moving printer nozzle creates a temporary fluid-like state, allowing the accurate placement in the matrix of silver–hydrogel ink circuits and electronic components. After printing, the entire matrix and embedded circuitry can be cured at 60 °C to form soft (Young’s modulus of less than 5 kPa) and stretchable (elongation of around 18) monolithic hydrogel electronics, whereas the conductive ink exhibits a high conductivity of around 1.4 × 103 S cm−1. We use our three-dimensional printing approach to create strain sensors, inductors and biological electrodes.

Electric Field Guided Fast and Oriented Assembly of MXene into Scalable Pristine Hydrogels for Customized Energy Storage and Water Evaporation Applications

AbstractThe assembly of MXene nanosheets into a hydrogel framework is key to their grand success in practical applications. However, the scalable realization of such stable structures is challenging and requires critically high dispersion concentration for gelation. Herein, a simple yet highly controllable approach for the development of 2D and 3D monolithic hydrogels of MXene via electro‐tunable ordered assembly is reported. Directional electrophoretic drag of MXene and their gelation by voltage‐controlled in situ released ions at the electrode interface gives rise to stable hydrogels with tunable sheet orientations. Nanosheets can be arranged in‐plane or out‐of‐plane depending on the parallel or radial field created by customized electrode assembly. Further, the gelation rate can be easily regulated by the applied potential to achieve self‐standing hydrogel films in a few tens of seconds. The 2D hydrogels display excellent supercapacitive performance of 395 F g−1 at 2 mV s−1 with high retention of 42% at 5000 mV s−1. In another customized application, the 3D‐monolithic MXene hydrogel displays outstanding performance as a solar‐thermal evaporator on behalf of its vertical sheet orientations, showing an excellent evaporation rate of 1.91 kg m−2 g−1. This simple, fast, scalable, and sheet orientation‐controlled assembly can pave the way for future development of MXene hydrogels and beyond.

Enhanced Macroporous Cationic Chitosan Hydrogel by Freezing and Thawing Method with Superadsorption Capacity for Anionic Dyes

In this study, we have developed a simple technique to prepare cationic chitosan hydrogel with interconnected porous structure using freeze–thaw process and the obtained hydrogel was named FCS hydrogel. Scanning electron microscopy (SEM) imaging discovered that the synthesized hydrogel demonstrated interconnected porous structure in the scope of 5–20 μm. We also showed that the FCS hydrogel exhibits pH responsiveness behavior, and demonstrated reversible swelling and de-swelling behaviors maintaining their mechanical stability. We demonstrate that the FCS hydrogel swelling capacity decreased at alkaline pH and rose with a decline in pH value. Besides, the FCS hydrogel presented specific surface area of 78.25 ± 8.75 m2 g−1, due to the cryogenic treatment of glutaraldehyde cross-linked chitosan hydrogel could increase the surface area and permeability of composite hydrogel and then strongly increasing the adsorption capacity. Subsequently, the FCS monolithic hydrogel tested dyes removal, which provides a high removal efficiency towards anionic dyes including congo red (CR) and sodium fluorescein (SFL) dyes. Significantly, we show that the FCS hydrogel could be regenerated and reused as an adsorbent for wastewater treatment without significant loss of pollutants removal efficiency over a number of adsorption and washing cycles. This study offers a promising environmental friendly and sustainable interconnected porous hydrogel for anionic dye removal from wastewater.

Gelatin-Based Colloidal Versus Monolithic Gels to Regulate Macrophage-Mediated Inflammatory Response.

Unlike conventional monolithic hydrogels with covalent cross-linkage that are typically elastic, colloidal gels assembled by reversibly assembled particles as building blocks have shown fascinating viscoelastic properties. They follow a gel-sol transition upon yielding and recover to the initial state upon the release of the shear force (so-called shear-thinning and self-healing behavior); this makes them an ideal candidate as injectable and moldable biomaterials for tissue regeneration. The immune response provoked by the implantation of the colloidal gels with special viscoelastic and structural features is critical for the successful integration of the implants with the host tissues, which, however, remains little explored. Since macrophages are known as the primary immune cells in determining the inflammatory response against the implants, we herein investigated in vitro macrophage polarization and in vivo inflammatory response induced by gelatin-based colloidal gels as compared to monolithic gels. Specifically, self-healing colloidal gels composed of pure gelatin nanoparticles, or methacrylate gelatin (GelMA) nanoparticles to allow secondary covalent cross-linkage were compared with GelMA bulk hydrogels. We demonstrated that hydrogel's elasticity plays a more dominant role rather than the structural feature in determining in vitro macrophage polarization evidenced by the stiffer gels inducing pro-inflammation M2 macrophage phenotype as compared to soft gels. However, subcutaneous implantation revealed a significantly alleviated immune response characterized by less fibrous capsule formation for the colloidal gels as compared to bulk gels of similar matrix elasticity. We speculated this can be related to the improved permeability of the colloidal gels for cell penetration, thereby leading to less fibrosis. In general, this study provided in-depth insight into the biophysical regulator of hydrogel materials on macrophage behavior and related inflammatory response, which can further direct future implant design and predict biomaterial-host interactions for immunotherapy and regenerative medicine. Impact statement Macrophages response to implanted biomaterials is a highly regulated process that influences device functionality and clinical outcome. Nowadays, the viscoelastic properties of colloidal versus monolithic hydrogels on macrophage phenotype in vitro and the host inflammatory response are not known. Our study found that colloidal hydrogels composed of nanoparticles of gelatin and methacrylate gelatin (GelMA) led to more anti-inflammatory polarization especially on soft colloidal gel (5.9 KPa) compared to bulk GelMA hydrogels. It suggested that macrophage response can be mechanically regulated by the viscoelastic signals of the hydrogels, which could be a promising strategy for the future design and application of novel biomaterials.

Thermal response of multi-layer UV crosslinked PEGDA hydrogels

Poly(ethylene glycol) diacrylate (PEGDA) hydrogels are ubiquitously used in a wide variety of applications in tissue engineering. In this study, the thermal response of multi-layered PEGDA hydrogels was investigated under various conditions of the temperature-controlled environments (8, 20, 37, and 45 °C) through gravimetric and volumetric methods. These multi-layered hydrogels were produced using a computer-controlled projection lithography and compared to the monolithic hydrogels fabricated through bulk photo-crosslinking. It was observed that the volume of multi-layered PEGDA hydrogels increased to about 10% at a temperature of 8 °C, while their volume decreased by 8% and 12% when stored at 37 °C and 45 °C, respectively. PEGDA hydrogel also showed an anisotropic characteristic where the axial dimensional change was about 43% higher than the lateral dimension. This finding is critical to inform the design and fabrication of PEGDA hydrogels to compensate for the axial and lateral volume changes during the application at different temperatures.

Effect of Functional Group on the Catalytic Activity of Lipase B from Candida antarctica Immobilized in a Silica-Reinforced Pluronic F127/α-Cyclodextrin Hydrogel

Surface modification plays a key role in the fabrication of highly active and stable enzymatic nanoreactors. In this study, we report for the first time the effect of various functional groups (epoxy, amine, trimethyl, and hexadecyl) on the catalytic performance of lipase B from Candida antarctica (CALB) incorporated within a monolithic supramolecular hydrogel with multiscale pore architecture. The supramolecular hydrogel formed by host-guest interactions between α-cyclodextrin (α-CD) and Pluronic F127 was first silicified to provide a hierarchically porous material whose surface was further modified with different organosilanes permitting both covalent anchoring and interfacial activation of CALB. The catalytic activity of nanoreactors was evaluated in the liquid phase cascade oxidation of 2,5-diformylfuran (DFF) to 2,5-furandicarboxylic acid (FDCA) under mild conditions. Results showed that high FDCA yields and high efficiency conversion of DFF could be correlated with the ability of epoxy and amine moieties to keep CALB attached to the carrier, while the trimethyl and hexadecyl groups could provide a suitable hydrophobic-hydrophilic interface for the interfacial activation of lipase. Cationic cross-linked β-CD was also evaluated as an enzyme-stabilizing agent and was found to provide beneficial effects in the operational stability of the biocatalyst. These supramolecular silicified hydrogel monoliths with hierarchical porosity may be used as promising nanoreactors to provide easier enzyme recovery in other biocatalytic continuous flow processes.

Colloidal hydrogels made of gelatin nanoparticles exhibit fast stress relaxation at strains relevant for cell activity

Viscoelastic properties of hydrogels such as stress relaxation or plasticity have been recognized as important mechanical cues that dictate the migration, proliferation, and differentiation of embedded cells. Stress relaxation rates in conventional hydrogels are usually much slower than cellular processes, which impedes rapid cellularization of these elastic networks. Colloidal hydrogels assembled from nanoscale building blocks may provide increased degrees of freedom in the design of viscoelastic hydrogels with accelerated stress relaxation rates due to their strain-sensitive rheology which can be tuned via interparticle interactions. Here, we investigate the stress relaxation of colloidal hydrogels from gelatin nanoparticles in comparison to physical gelatin hydrogels and explore the particle interactions that govern stress relaxation. Colloidal and physical gelatin hydrogels exhibit comparable rheology at small deformations, but colloidal hydrogels fluidize beyond a critical strain while physical gels remain primarily elastic independent of strain. This fluidization facilitates fast exponential stress relaxation in colloidal gels at strain levels that correspond to strains exerted by cells embedded in physiological extracellular matrices (10-50%). Increased attractive particle interactions result in a higher critical strain and slower stress relaxation in colloidal gels. In physical gels, stress relaxation is slower and mostly independent of strain. Hence, colloidal hydrogels offer the possibility to modulate viscoelasticity via interparticle interactions and obtain fast stress relaxation rates at strains relevant for cell activity. These beneficial features render colloidal hydrogels promising alternatives to conventional monolithic hydrogels for tissue engineering and regenerative medicine. Statement of significanceIn the endeavor to design biomaterials that favor cell activity, research has long focused on biochemical cues. Recently, the time-, stress-, and strain-dependent mechanical properties, i.e. viscoelasticity, of biomaterials has been recognized as important factor that dictates cell fate. We herein present the viscoelastic stress relaxation of colloidal hydrogels assembled from gelatin nanoparticles, which show a strain-dependent fluidization at strains relevant for cell activity, in contrast to many commonly used monolithic hydrogels with primarily elastic behavior.

Patterned Electrode Assisted One-Step Fabrication of Biomimetic Morphing Hydrogels with Sophisticated Anisotropic Structures.

Anisotropic structures are ubiquitous in nature, affording fascinating morphing behaviors. Biomimetic morphing materials can be developed by spatially controlling the orientations of molecules or nanofillers that produce anisotropic responses and internal stresses under external stimuli. However, it remains a serious challenge to fabricate materials with sophisticated anisotropic architectures. Here, a facile strategy to fabricate morphing hydrogels with elaborately ordered structures of nanosheets, which are oriented under distributed electric field and immobilized by polymerization to form a poly(N‐isopropylacrylamide) matrix, is proposed. Diverse sophisticated anisotropic structures are obtained by engineering the electric field through the patterns and relative locations of the electrodes. Upon heating, the monolithic hydrogels with through‐thickness and/or in‐plane gradients in orientation of the nanosheets deform into various three‐dimensional configurations. After incorporating gold nanoparticles, the hydrogels become photoresponsive and capable of programmable motions, for example, dynamic twisting and flipping under spatiotemporal stimuli. Such a strategy of using patterned electrodes to generate distributed electric field should be applicable to systems of liquid crystals or charged particles/molecules to direct orientation or electrophoresis and form functional structures. The biomimetically architectured hydrogels would be ideal materials to develop artificial muscles, soft actuators/robots, and biomedical devices with versatile applications.

Ethanol fermentation using macroporous monolithic hydrogels as yeast cell scaffolds

Ethanol fermentation with a hybrid system containing free and immobilized yeast cells on a macroporous monolithic hydrogel scaffold was investigated. Cell immobilization was achieved using N-isopropylacrylamide (NIPA) and methoxy triethyleneglycol acrylate (MTGA) hydrogels having macroporous monolithic structures containing interconnected micrometer-sized macropores. The immobilized cells grow within the hydrogel and can exit through the macropores into the fermentation medium, and thus a hybrid bioreactor consisting of free and immobilized yeast cells is constructed. The transformation of d-glucose to ethanol using Saccharomyces cerevisiae in batch and continuous fermentation processes was examined. Ethanol was successfully fermented using the macroporous hydrogels, whereas the conventional nonporous NIPA hydrogel does not effectively act as a cell scaffold. In continuous fermentation, the hybrid system containing both free yeast cells and those immobilized in the macroporous MTGA hydrogel showed higher ethanol productivity than the control system containing only free cells. Crucially, the macroporous hydrogel allowed the stable growth of immobilized yeast cells, resulting in a high cell density in the reactor. The hybrid system under steady-state fermentation had free and immobilized cell densities of 1.72 kg-free-cell/m3 and 29 kg-immobilized-cell/m3-gel, respectively, and the ethanol productivities 0.421 kg-ethanol/(kg-free-cell·h) and 0.128 kg-ethanol/(kg-immobilized-cell·h), respectively.

Direct Ink Writing of Hierarchically Porous Cellulose/Alginate Monolithic Hydrogel as a Highly Effective Adsorbent for Environmental Applications

Cellulose has been extensively studied for environmental applications owing to its biocompatible, nontoxic, and cost-effective properties. Herein, a simple method for the design of printable cellul...

Monolithic hydrogel nanowells-in-microwells enabling simultaneous single cell secretion and phenotype analysis.

Cytokine secretion is a form of cellular communication that regulates a wide range of biological processes. A common approach for measuring cytokine secretion from single cells is to confine individual cells in arrays of nanoliter wells (nanowells) fabricated using polydimethylsiloxane. However, this approach cannot be easily integrated in standard microwell plates in order to take advantage of high-throughput infrastructure for automated and multiplexed analysis. Here, we used laser micropatterning to fabricate monolithic hydrogel nanowells inside wells in a microwell plate (microwells) using polyethylene glycol diacrylate (PEGDA). This approach produces high-aspect ratio nanowells that retain cells and beads during reagent exchange, enabling simultaneous profiling of single cell secretion and phenotyping via immunostaining. To limit contamination between nanowells, we used methylcellulose as a media additive to reduce diffusion distance. Patterning nanowells monolithically in microwells also dramatically increases density, providing ∼1200 nanowells per microwell in a microwell plate. Using this approach, we profiled IL-8 secretion from single MDA-MB-231 cells, which showed significant heterogeneity. We further profiled the polarization of THP-1 cells into M1 and M2 macrophages, along with their associated IL-1β and CCL-22 secretion profiles. These results demonstrate the potential to use this approach for high-throughput secretion and phenotype analysis on single cells.

Polyaromatic hydrocarbon inner-structured carbon nanodots for interfacial enhancement of carbon fiber composite.

It is well known that carbon substances with a polyaromatic hydrocarbon (PAH) inner structure only form at high temperature. In this work, we introduce fabrication of massive and PAH inner-structured carbon nanodots (CNDs) via hydrothermal treatment of glucose aqueous solution in the monolithic methyl silicone hydrogel at 200 °C. During the carbonization process, all the precursor solution is confined in nano-vessels (2–20 nm) of the thermostable methyl silicone hydrogel, thus forming CNDs without aggregation. The resulting CNDs, with a yield of 65%, were separated facilely and characterized using various spectroscopy and microscopy techniques. The glucose-derived CNDs have diameters of 2–5 nm and contain 18.9 wt% carboxyl groups, and their aqueous solubility depends on the pH. The CNDs consist of large PAH clusters, confirmed by solid-state 13C NMR, which were different to other reported carbon substances prepared at similar low temperatures. The formation mechanism of the PAH structure in the CNDs probably relates to the high interfacial energy of the prewetted superhydrophobic methyl silicone nano-framework in the hydrogel. Moreover, the tunable fluorescence properties of the CNDs prepared using this method can be attributed to the arene carboxylic groups in the CNDs. Finally, the resultant PAH CNDs with abundant groups were applied as a sizing in carbon fiber (CF) composite fabrication, resulting in an obvious interface enhancement of the CF/epoxy composite.