Poly(ethylene Glycol) Diacrylate Concentration Research Articles

Projection Stereolithography 3D-Printed Bio-Polymer with Thermal Assistance.

A stereolithography process with thermal assistance is proposed in this work to address the tradeoff between the flowability and the high concentration of solute loadings at room temperature, through which the improved performance of polymers prepared using stereolithography 3D printing can be achieved. For the experiment, polyethylene glycol diacrylate (PEGDA) with a high molecular weight of 4000 is adopted to improve the mechanical properties of 2-Hydroxyethyl methacrylate (HEMA). For the polymer of HEMA, the highest soluble concentration of PEGDA is about 20 wt% at 25 °C (room temperature) while the concentration could be raised up to 40 wt% as the temperature increases to 60 °C. The 3D printing tests showed that the objects could be easily fabricated with the HEMA polymer loaded with 40 wt% of PEGDA through the thermally assisted projection stereolithography technology. By adding the 40 wt% of PEGDA, the Young's modulus has been enhanced by nearly 390% compared to the HEMA resin without solute, of which the Young's modulus is 63.31 ± 2.72 MPa. The results of the cell proliferation test proved that the HEMA resin loaded with PEGDA led to a better biocompatibility compared to the HEMA resin without the loading of the PEGDA solute. All of the results demonstrate that the polymer loaded with high solute is feasible to be precisely 3D-printed using the projection stereolithography process with thermal assistance, and the improved mechanical properties are beneficial for biomedical applications.

Fabrication of 3D-Printed Contact Lens Composed of Polyethylene Glycol Diacrylate for Controlled Release of Azithromycin.

Since three-dimensional (3D)-printed tablets were approved by the United States Food and Drug Administration (FDA), 3D printing technology has garnered increasing interest for the fabrication of medical and pharmaceutical devices. With various dosing devices being designed for manufacture by 3D printing, 3D-printed ophthalmic formulations to release drugs have been one such target of investigation. In the current study, 3D-printed contact lenses designed for the controlled release of the antibiotic azithromycin were produced by vat photopolymerization, and the effect of the printer ink composition and a second curing process was investigated. The azithromycin-loaded contact lenses were composed of the cross-linking reagent polyethylene glycol diacrylate (PEGDA), PEG 400 as a solvent, a photoinitiator, and azithromycin. The 3D-printed contact lenses were fabricated successfully, and formulations with lower PEGDA concentrations produced thicker lenses. The mechanical strength of the PEGDA-based contact lenses was dependent on the amount of PEGDA and was improved by a second curing process. Drug release from 3D-printed contact lenses was reduced in the samples with a second curing process. The azithromycin-loaded contact lenses exhibited antimicrobial effects in vitro for both Gram-positive and -negative bacteria. These results suggest that 3D-printed contact lenses containing antibiotics are an effective model for treating eye infections by controlling drug release.

Fabrication and characterization of photosensitive non-isocyanate polyurethane acrylate resin for 3D printing of customized biocompatible orthopedic surgical guides.

Three-dimensional (3D)-printed orthopedic surgical guides have the potential to provide personalized precision treatment. Non-isocyanate polyurethane (NIPU) is commonly used in the 3D printing of biomedical materials but its application in the orthopedic surgical guide is limited by poor mechanical properties and biocompatibility. In this study, we fabricated non-isocyanate polyurethane acrylate (NIPUA) photosensitive resin with superior biocompatibility and mechanical properties required for 3D-printed orthopedic surgical guides. NIPU prepolymer was synthesized by a ring-opening reaction and a ring acrylation reaction. NIPUA was further synthesized using polyethylene glycol diacrylate (PEGDA) as a modified material based on sustainable synthesis with reduced synthesis time. NIPUA showed the best tensile and flexural strengths when the PEGDA content reached 12 wt.%. NIPUA exhibited higher thermal stability, hemocompatibility, superior biocompatibility to ME3T3-E1 bone cells and C1C12 muscle cells, and non-immunogenic effect toward macrophages compared with commercial photosensitive resins. Commercial resins triggered a severe inflammatory response during in vivo implantation, but this effect was not observed during NIPUA implantation. Transcriptome analysis showed downregulation of cell death and cell cycle disruption-related genes, such as CDK2, CDKN1a, and GADD45a, and upregulation of autophagy and anti-tumor activity-related genes, such as MYC, PLK1, and BUB1b, in NIPUA-treated MC3T3-E1 cells compared with commercial resin-treated MC3T3-E1 cells. In conclusion, NIPUA resin showed excellent mechanical and thermal properties as well as good biocompatibility toward bone cells, muscle cells, and macrophages, suggesting its possible application in the 3D printing of customized orthopedic surgical guides.

Fabrication of a superhydrophilic/underwater superoleophobic PVDF membrane via thiol–ene photochemistry for the oil/water separation

The direct discharge of oily wastewater into the environment is considered one of the greatest threats to the ecological environment. Membrane technology is considered as an efficient strategy to treat oily wastewater. However, the membrane fouling caused by oil adsorption has intensively impeded its practical utilization in oil/water separation. This work aims to fabricate an anti-oil-fouling membrane for the effective separation of oil/water emulsions. The PEGylated poly(vinylidene fluoride) (PVDF) membrane was synthesized via thiol–ene photochemistry with poly(ethylene glycol) diacrylate (PEGDA) and 3,6-dioxa-1,8-octanedithiol (DOT) as the modifiers. The results of scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) mapping analysis revealed that the PEGylated layers show uniform distribution on the membrane surface by regulating the feed PEGDA concentration. The superhydrophilic and underwater superoleophobic characteristics of the PEGylated membrane provided oil-adhesion resistance to the membranes. The membrane grafted with a high amount of PEGylated layers shows a low pure water flux, due to the pore blockage. The PEGylated membrane possesses the stable surface wettability and permeation performance of emulsion. The separation efficiency of PEGylated membranes for multiple emulsions is greater than 99%, and the highest rejection value is as high as 99.9%. After the three-cycle filtration of emulsified pump oil solution, the flux recovery ratio of membranes still reaches 90%, indicating an outstanding fouling resistance to emulsified oily matters. This work provides a feasible strategy to prepare the antifouling PVDF membrane used for the oil/water separation.

Glassy and compressed nanoemulsions stabilized with sodium dodecyl sulfate in the presence of poly(ethylene glycol)-diacrylate.

The rheology of concentrated nanoemulsions is critical for their formulation in various applications, such as pharmaceuticals, foods, cosmetics, and templating advanced materials. The rheological properties of nanoemulsions depend on interdroplet interactions, Laplace pressure, dispersed phase volume fraction, and continuous phase properties. The interdroplet forces can be tuned by background electrolytes (i.e., charge screening), surfactant type, the excess surfactant micelle concentration, and depletant molecules such as polymer chains. In the current research, we study the effect of varying the content of poly(ethylene glycol)-diacrylate (PEGDA) on the interfacial tension of the water-oil phase and rheological properties of concentrated nanoemulsions with 50% and 60% volume fractions. Sodium dodecyl sulfate (SDS) is used as the ionic surfactant. The final concentrated nanoemulsions are repulsive according to overall interaction potentials and are in the glass and compressed states based on the effective volume fraction estimation. They contain nearly same SDS concentration on the droplet surface and also in the bulk, but a different amount of PEGDA. The scaled rheological properties of the glassy nanoemulsions show a higher dependency on the PEGDA content and the possible effect of polymer-surfactant complexations compared to those of the compressed ones. This dependency is more pronounced in small strain amplitudes but not in large strains in the non-linear regime. These results provide insights into formulating concentrated nanoemulsions with controlled rheology for expanded application areas.

Poly(methacrylic acid) hydrogels crosslinked by poly(ethylene glycol) diacrylate as pH-responsive systems for drug delivery applications

Hydrogels are attractive materials for drug delivery applications due to biocompatible, porous structure with the possibility to load and deliver drugs in a controllable manner. In this paper, poly(methacrylic acid) (PMAA) hydrogels are described, which are synthesized by free-radical polymerization, using poly(ethylene glycol) diacrylate (PEGDA) as a crosslinker. Influence of the PEGDA content on hydrogel properties was investigated and compared to commonly used crosslinker - N,N?-methylenebisacrylamide (MBA). The increasing concentration of crosslinkers led to a higher degree of crosslinking, which was demonstrated by a higher degree of conversion, lower swelling capacity, and improved thermal stability and mechanical properties. Also, the PEGDA-crosslinked hydrogels demonstrated a higher degree of crosslinking than the corresponding MBA-crosslinked hydrogels. Potential application of the synthesized hydrogels for controlled drug delivery was investigated by using two model drugs - oxaprozin and ciprofloxacin. In vitro drug release tests indicated that the interactions between drug, polymer and medium have a key influence on the drug release behavior, rather than the swelling rate. Drug release tests in simulated gastrointestinal conditions indicated that PEGDA-crosslinked PMAA hydrogels are suitable for colon-targeted delivery of oxaprozin.

Process optimization and optimal tolerancing to improve dimensional accuracy of vat-photopolymerized functionally graded hydrogels

Functionally graded hydrogels with variation in material composition are useful for a variety of applications in domains like biomedical engineering and soft robotics. Recent developments in 3D printing have enabled the production of such graded hydrogels. However, the variation in the composition of these hydrogels layer-wise can be challenging in terms of selecting optimal 3D printing process parameters and maintaining geometrical accuracy. Unless corrective measures are taken, the variations in material composition can cause a loss in print fidelity and lead to dimensional deviations in the printed samples. In-depth studies have not been reported to address these challenges in the 3D printing of functionally graded hydrogels, and guidelines are not available for correcting the geometric deviations so produced. In this work, we study the deviations in lateral dimensions in functionally graded polyethylene glycol diacrylate (PEGDA) hydrogels produced using digital light processing (DLP) 3D printer and present a method to correct these deviations. The methodology involves specification of optimal printer parameters for each material composition and giving appropriate tolerances on the CAD model. The lateral dimensions of the printed part depend on PEGDA concentration, exposure time, layer thickness and print time. For obtaining accurate samples after printing and swelling, the printer parameters must be changed whenever a change in material composition occurs. Further, the printer parameters have to be chosen such that swelling induced cracking is reduced while maintaining good print fidelity. The tolerance on the CAD model has to consider the lateral deviation that occurs at the edges due to printing and the bulk increase that occurs due to swelling. We demonstrate this method by printing functionally graded PEGDA samples with good print fidelity and dimensional accuracy.

Heterogeneous spheroids with tunable interior morphologies by droplet-based microfluidics

Heterogeneous spheroids that mimic the complex three-dimensional environment of natural tissues are needed in various biomedical applications. Geometric cues from cellular matrix play invaluable roles in governing cell behavior and phenotype. However, the structural complexity of interior morphologies of spheroids is currently limited due to poor spatial resolution of positioning/orientation of cellular constructs. Here, a coaxial capillary microfluidic device is developed to generate gelatin methacrylate (GelMA) microspheres with tunable dimensions and interior morphologies, such as core-shell, or microspheres with interior undulated wavy, or spiral canals, by manipulating the two-phase flow of hydrogel precursor solution and methylcellulose solution. The formation of diverse and exquisite interior morphologies is caused by the interacting viscous instabilities of the two-phase flow in the microfluidic system, followed by water-in-oil emulsion and photo-initiated polymerization. Polyethylene glycol diacrylate (PEGDA) is incorporated into the GelMA solution to tune the mechanical properties of the fabricated microspheres, and an optimized concentration of PEGDA is confirmed by evaluating the in vitro proliferation and vascularization of human umbilical vein endothelial cells. Further, a heterogeneous spheroid with spiral blood vessel lumen is constructed to demonstrate the versatility and potential of the proposed droplet-based microfluidic approach for building functional tissue constructs.

Synthesis and characterization of semi-IPN hydrogels composed of sodium 2-acrylamido-2-methylpropanesulfonate and poly(ε-caprolactone) diol for controlled drug delivery

Semi-interpenetrating polymer network (semi-IPN) hydrogel of sodium 2-acrylamido-2-methylpropane sulfonate (Na-AMPS) and poly(ε-caprolactone) (PCL) diol for drug delivery applications was synthesized via free radical UV-photopolymerization technique using 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone as an initiator and poly(ethylene glycol) diacrylate (PEGDA) as a crosslinker. The hydrogels' chemical structure and internal morphology have been explored using Fourier-transform infrared spectroscopy and scanning electron microscopy. The influence of PCL diol and PEGDA concentrations on the synthesized semi-IPN hydrogel properties was investigated. The semi-IPN hydrogel can increase the elasticity of the hydrogel while simultaneously providing enough water uptake and water retention. Furthermore, the semi-IPN hydrogel was non-cytotoxic to mouse fibroblasts L929 cells. Finally, ciprofloxacin (CIP) was used as a model drug and was efficiently encapsulated into the semi-IPN hydrogels. Drug loading capacity was enhanced with increasing PCL diol and CIP content. It was also observed that the PCL diol and CIP contents had a marked influence on the release profiles. Thus, the rate of release could be designed by changing the Na-AMPS to PCL diol ratio and CIP content. Drug release was found to be both diffusion and swelling-controlled in accordance with the Fickian and non-Fickian transport mechanisms. In the light of the results obtained, their easy formability, their appropriate mechanical and physical properties make P(Na-AMPS)/PCL diol semi-IPN hydrogels are the potential candidates for use as drug carrier and controlled drug release materials in the biomedical field.

Synthesis of porous polymers by means of Michael addition reaction of multifunctional acetoacetate and poly(ethylene glycol) diacrylate

Michael-addition reaction between multifunctional-acetoacetate, meso-erythritol tetra-acetoacetate (ETAA) or d-sorbitol hexa-acetoacetate (SHAA), and poly(ethylene glycol) diacrylate (PEGDA) has been investigated to obtain the corresponding network polymer. The reactions in mixtures of ethanol (EtOH) and dimethyl sulfoxide (DMSO) using 1,8-diazabicyclo[5.4.0]undecane-7-ene (DBU) as a catalyst successfully yielded porous polymers. Polymerization conditions, such as EtOH/DMSO volume ratio, DBU/PEGDA feed ratio, and monomer concentration, strongly affected the morphology of the network polymer products, i.e., gel, porous polymer, or precipitate. The surface morphology of the porous polymers showed connected spheres with diameters ranged from 2 μm to 50 μm. The monomer concentration and molar mass of PEGDA affected the diameter of the spheres in the porous polymers. All the porous polymers were soft and flexible, and were not breakable by compression. Various solvents were absorbed into the porous polymer due to their high affinity with polyethylene glycol units in the network structure.

Cross-linking of poly (ether-block-amide) by poly (ethylene glycol) diacrylate to prepare plasticizing-resistant CO2-selective membranes

In this study, poly (ethylene glycol) diacrylate (PEGDA) comprising CO2-philic ether oxygen groups was used as a cross-linking agent to develop plasticizing-resistant poly (ether-block-amide) (Pebax-1657) composite membranes with high performance for CO2 separation. The effect of PEGDA concentration on the structure and properties of the membranes as well as gas separation efficiency was investigated. The FT-IR analysis and swelling measurements confirmed the influential role of PEGDA as the cross-linking agent in the prepared membranes. Based on the performed characterization analyzes, it was found that the concentration of the cross-linking agent strongly affects the structural and CO2 separation properties of the cross-linked Pebax membranes. By introducing a cross-linking reaction, the tightness and crystallinity of modified Pebax membranes enhanced compared to the uncross-linked Pebax membrane. The DSC analysis indicated the Tg of the prepared Pebax membranes increased from −54.7 °C to −52.45 °C by increasing the PEGDA content. When the PEGDA concentration increased from 0 wt% to 6 wt%, the selectivity of CO2/N2, CO2/CH4, and CH4/N2 enhanced by 294%, 105%, and 92%, respectively, while the gas permeabilities slightly decreased. The cross-linked Pebax-1657 membrane containing 6 wt% of PEGDA surpassed the Robeson’s upper bound and denoted a prosperous separation performance in the case of CO2 separation from CH4 and N2, compared to the uncross-linked Pebax.

Gelatine-based drug-eluting bandage contact lenses: Effect of PEGDA concentration and manufacturing technique

Drug-eluting bandage contact lenses (BCLs) have been widely studied as an alternative to eye drops due to their ability to increase the drug residence time and bioavailability as well as improve patient compliance. While silicone hydrogel polymers are commonly used in drug-eluting BCLs due to their transparency, mechanical properties and high oxygen permeability, gelatine hydrogels are also clear, flexible and have high oxygen permeability and may therefore be suitable contact lens materials. Moreover, the rheological properties of gelatine hydrogels allow their use as inks in extrusion-based 3D printers, therefore opening the door to a wide range of applications. Drug-loaded gelatine methacryloyl (GelMA) BCLs with different concentrations of poly (ethylene glycol) diacrylate (PEGDA) were prepared using solvent casting and 3D printing. The prepared lenses were characterised for their swelling ratio, in vitro degradation, and drug release properties. The results showed that the incorporation of 10% PEGDA improved the lenses’ resistance to handling and protected them during degradation testing, reduced the swelling ratio and prolonged the release of dexamethasone (DEX). Both techniques were deemed suitable to use in the manufacturing of drug-eluting BCLs noting that the optimal formulation may vary according to the preparation technique utilised.

On shockwave propagation and attenuation in poly(ethylene glycol) diacrylate hydrogels

An analytical model is developed to predict shockwave propagation and attenuation in hydrogels by combining the classical method of shock characteristics and a solution for the shock front structure. To guide the development of the model, molecular dynamics (MD) simulations are performed. Specifically, a one-dimensional shock pulse in poly(ethylene glycol) diacrylate (PEGDA) hydrogels is simulated with the nonequilibrium MD method. The role of polymer concentration on the shock response is evaluated by constructing hydrogels with 20, 35, and 50wt% PEGDA concentrations in an idealized crosslinked network. Steady-state pressure-density and shock-particle velocity relationships are established using the Murnaghan equation of state. Shock front structure is characterized by a power-law equation that relates the shock front thickness with shock pressure. These results are used as critical input for the shock propagation and attenuation model. The model is then evaluated via comparison with the classical method of characteristics. It shows significant improvement in accuracy and successfully captures salient features of shockwave attenuation, including the shock pressure amplitude, the velocities of the shock and release waves, and the attenuation timeline. Hydrogels with higher polymer concentrations exhibit a shorter attenuation time at all particle velocities studied. This behavior is attributed to differences in bulk properties and shock front structure in hydrogels with different polymer/water concentrations.

3D bioprinting of mechanically tuned bioinks derived from cardiac decellularized extracellular matrix

3D bioprinting is a powerful technique for engineering tissues used to study cell behavior and tissue properties in vitro. With the right formulation and printing parameters, bioinks can provide native biological and mechanical cues while allowing for versatile 3D structures that recapitulate tissue-level organization. Bio-based materials that support cellular adhesion, differentiation, and proliferation - including gelatin, collagen, hyaluronic acid, and alginate - have been successfully used as bioinks. In particular, decellularized extracellular matrix (dECM) has become a promising material with the unique ability to maintain both biochemical and topographical micro-environments of native tissues. However, dECM has shown technical limitations for 3D printing (3DP) applications posed by its intrinsically low mechanical stability. Herein, we report hydrogel bioinks composed of partially digested, porcine cardiac decellularized extracellular matrix (cdECM), Laponite-XLG nanoclay, and poly(ethylene glycol)-diacrylate (PEG-DA). The Laponite facilitated extrusion-based 3DP, while PEG-DA enabled photo-polymerization after printing. Improving upon previously reported bioinks derived from dECM, our bioinks combine extrudability, shape fidelity, rapid cross-linking, and cytocompatibility in a single formulation (> 97% viability of encapsulated human cardiac fibroblasts and > 94% viability of human induced pluripotent stem cell derived cardiomyocytes after 7 days). The compressive modulus of the cured hydrogel bioinks was tunable from 13.4-89 kPa by changing the concentration of PEG-DA in the bioink formulation. Importantly, this span of mechanical stiffness encompasses ranges of tissue stiffness from healthy (compressive modulus ~5-15 kPa) to fibrotic (compressive modulus ~30-100 kPa) cardiac tissue states. The printed constructs demonstrated shape fidelity, adaptability to different printing conditions, and high cell viability following extrusion and photo-polymerization, highlighting the potential for applications in modeling both healthy and fibrotic cardiac tissue.

UV irradiation-assisted cross-linking of high molecular weight poly (ethylene oxide) with poly (ethylene glycol) diacrylate to prepare CO2 selective membranes

In this work, the high molecular weight poly (ethylene oxide) (PEO) was cross-linked under UV irradiation to decrease its crystallinity in order to prepare a high-performance CO2-selective membrane. Poly (ethylene glycol) diacrylate (PEGDA) containing CO2-philic ether oxygen group was used as both photo-initiator and cross-linking agent. It was found that the crystallinity degree from 82.4% for the neat PEO membrane decreased to 65.4% for the cross-linked PEO membrane by the proposed cross-linking technique. The observations indicated that the structural and gas separation properties of the cross-linked PEO membranes strongly depend on the PEGDA concentration and UV irradiation time. When the PEGDA concentration was between 3 and 7 %wt and at UV irradiation time of 30 min, the prepared membrane overcame Robeson upper bound and indicated a fairly good separation performance in the case of CO2 separation from N2, compared to the similar cross-linked PEG-based membranes in the literature.

Ceramic-Doped in Cross-Linked Solid Polymer Electrolyte for Solid-State Batteries

Replacing liquid electrolytes with solid-state Li-ion conductors is one way to achieve safe rechargeable batteries with high energy density. Semi-interpenetrating polymer network (s-IPN) was synthesized from the mixture of poly(propylene carbonate), poly(ethylene glycol) methyl ether acrylate, poly(ethylene glycol) diacrylate (PEGDA), and lithium bis(trifluoromethane)sulfonamide salt via one-pot thermal curing method. The crosslinker PEGDA content and salt concentration were optimized and the best result was abtained at a molar ratio of EO:Li ∼ 14:1. The electrolyte with higher salt concentration had lower ionic conductivity, consistent with higher glass transition temperature of poly(ethylene glycol) chain. Differential scanning calorimetry has shown a low degree of crystallinity when lithium lanthanum zirconate doped tantalum (LLZTO) was added to the s- IPN electrolyte which corresponds to an increase in ionic conductivity, 4.5 x 10-4 S/cm at 40°C. The resulting composite polymer electrolyte (CPE) showed high electrochemical stability up to 5.5 V. Lithium plating and stripping at 0.1 mA/cm2 at room temperature revealed a stable Li/electrolyte interface and no dendrite formation. Cycling performance of a full solid-state cell made with the CPE using LiFePO4 as the cathode will be discussed. Figure 1

Printability of External and Internal Structures Based on Digital Light Processing 3D Printing Technique.

The high printing efficiency and easy availability of desktop digital light processing (DLP) printers have made DLP 3D printing a promising technique with increasingly broad application prospects, particularly in personalized medicine. The objective of this study was to fabricate and evaluate medical samples with external and internal structures using the DLP technique. The influence of different additives and printing parameters on the printability and functionality of this technique was thoroughly evaluated. It was observed that the printability and mechanical properties of external structures were affected by the poly(ethylene glycol) diacrylate (PEGDA) concentration, plasticizers, layer height, and exposure time. The optimal printing solutions for 3D external and internal structures were 100% PEGDA and 75% PEGDA with 0.25 mg/mL tartrazine, respectively. And the optimal layer height for 3D external and internal structures were 0.02 mm and 0.05 mm, respectively. The optimal sample with external structures had an adequate drug-loading ability, acceptable sustained-release characteristics, and satisfactory biomechanical properties. In contrast, the printability of internal structures was affected by the photoabsorber, PEGDA concentration, layer height, and exposure time. The optimal samples with internal structures had good morphology, integrity and perfusion behavior. The present study showed that the DLP printing technique was capable of fabricating implants for drug delivery and physiological channels for in vivo evaluation.

Complex emulsions for shape control based on mass transfer and phase separation.

Complex emulsions are used to fabricate new morphologies of multiple Janus droplets, evolving from non-engulfing to complete engulfing core/shell configuration. The produced droplets contain an aqueous phase of dextran (DEX) solution and an oil phase, which is mixed with ethoxylated trimethylolpropane triacrylate (ETPTA) and poly(ethylene glycol) diacrylate (PEGDA). The PEGDA in the oil phase is transferred into the aqueous phase to form complex morphologies due to the phase separation of PEGDA and DEX. The effects are investigated including the ratio of oil to aqueous phase, the content of initial PEGDA, DEX and surfactants, and the type of surfactants. DEX/PEGDA-ETPTA core/shell-single phase Janus droplets are formed with an increasing engulfed oil droplet into the aqueous droplet while the ratio of oil to aqueous phase increases or the initial PEGDA content increases. The high DEX content leads to the DEX-PEGDA-ETPTA doublet Janus. The use of surfactants polyglycerol polyricinoleate (PGPR) and Span 80 results in the formation of DEX/PEGDA/ETPTA single core/double shell and DEX/PEGDA-ETPTA core/shell-single phase Janus droplets, respectively. These complex emulsions are utilized to fabricate solid particles of complex shapes. This method contributes to new material design underpinned by mass transfer and phase separation, which can be extended to other complex emulsion systems.

Sodium alginate-polyethylene glycol diacrylate based double network fiber: Rheological properties of fiber forming solution with semi-interpenetrating network structure

In order to prepare the high mechanical properties fiber with double network, sodium alginate (SA)/polyethylene glycol diacrylate (PEGDA) gel solution with semi-interpenetrating network structure was prepared by using “one-pot” method. Rheological properties of SA/PEGDA gel solution were studied at steady state mode and dynamic mode respectively. The results showed that the SA/PEGDA solution’s apparent viscosity was 0.67 Pa·s at PEGDA of 20 wt%, smaller 92.8% than that of the pure SA solution. When PEGDA content was 20 wt%, the consistency coefficient (k) of the solution reached the minimum (0.57). It meant the flow properties of the solution were the optimal at PEGDA of 20 wt%. Moreover, changes in the storage modulus (G′) and the loss modulus (G″) were found to be dependent on PEGDA content and temperature. The tanδ was greater higher than 1, which meant the spinning solution exhibited viscoelastic behavior of liquid-like properties.

Hyaluronic acid-based hydrogels with independently tunable mechanical and bioactive signaling features.

Extracellular matrix provides critical signaling context to resident cells through mechanical and bioactive properties. To realize the potential of tissue engineering and regenerative medicine, biomaterials should allow for the independent control of these features. This study investigates a hydrogel system based on thiol-modified hyaluronic acid (HA-S) and polyethylene glycol diacrylate (PEGDA). The mechanical properties of HAS-PEGDA are dictated by two cytocompatible crosslinking reactions that occur at distinct time points: a rapid, Michael-type nucleophilic addition reaction between HA-thiols and PEG-acrylates and a prolonged maturation of disulfide crosslinks from remaining thiols. It is hypothesized that these reactions would enable the independent tuning of the mechanical and bioactive features of HAS-PEGDA. Rheological studies confirmed that initial gelation reached completion by 1 day, at which point the shear modulus was proportional to the concentration of PEGDA. Over time, the shear modulus evolved dramatically, and final stiffness depended on the availability of HA-thiols. The addition of PEG-monoacrylate (PEGMA) after the initial gelation occupied a percentage of remaining thiols to prevent disulfide crosslinking, decreasing the steady-state stiffness in a dose-dependent manner. A fraction of the PEGMA was then replaced with acrylated peptide ligands to introduce specific bioactivity to the otherwise non-cell-adhesive network. The degree of latent stiffening was controlled by the total amount of peptide-PEGMA, while adhesivity was tuned with the balance of bioactive and inactive peptides. The functional effects of the tunable mechanical and bioadhesive ligand properties were confirmed with assays of cell adhesion and morphology.