Pure Poly(ethylene Glycol) Diacrylate Research Articles

Precise processing of pure undiluted PEGDA via inkjet printing for drug release systems

Abstract Poly(ethylene glycol) diacrylate (PEGDA) is a common polymer in the field of biomedical engineering and can be used for the production of drug delivery systems (DDS). The main advantages of PEGDA are biocompatibility and the ability to alter the physical and chemical properties, thereby ensuring individualized drug release behaviour. The processing of PEGDA via inkjet printing is relevant for the production of DDS. This can be challenging due to the high viscosity of pure PEGDA. In this work, PEGDA, with a molecular weight of 250 g/mol (PEGDA250), was inkjet printed using a Nanoplotter 2.1 with a piezoelectric heatable NanoTip HV-J-H printhead (GeSiM mbH, Radeberg, Germany) at different voltages and temperatures. Droplet generation was analysed in terms of droplet volume and angle deviations. PEGDA250 can be inkjet printed reproducibly in a voltage range of 60 V - 80 V at room temperature (20 °C) or heated up to 38 °C. The average volume of heated (38 °C) PEGDA250 droplets was approximately 110 pl - 150 pl higher than the droplet volume of PEGDA250 in the unheated state. The average angle deviations of main and satellite droplets were mostly < 3°. Increasing voltage or excessive heating of more than 38 °C caused greater instabilities in the droplet generation as well as larger satellite droplets which can affect the accuracy negatively. The studies have shown that PEGDA250 can be processed via inkjet printing and thus can be used as a drug carrier for DDS without the need for mixing with a solvent.

Stereolithography Printing and Mechanical Properties of Polyethylene Glycol Diacrylate/Hexagonal Boron Nitride Ceramic Composites

To enhance the mechanical properties of bioceramic composite bone scaffolds, a composite paste of polyethylene glycol diacrylate (PEGDA) and hexagonal boron nitride (h‐BN) with a solid content of up to 42 wt% was developed in this study. The part was produced using stereolithography (SLA). The SLA printing parameters and material ratios of the paste were optimized through a homogeneous design and mechanical property tests. The results indicate that the single‐line curing width of the PEGDA/h‐BN paste in the XY plane ranged from 172 to 209 μm, while the curing depth of a single layer along the Z‐axis ranged from 99 to 154 μm. Laser power was identified as the primary factor influencing both the width and depth of curing. The compressive strength of the printed sample of PEGDA/h‐BN ceramic composite paste was measured at 222.4 ± 5.6 MPa, which is 61 times greater than the compressive strength of a pure PEGDA structure and comparable to that of cortical bone (100‐230 MPa). Finally, the superior biocompatibility of PEGDA/h‐BN ceramics was confirmed through cytotoxicity experiments. Consequently, PEGDA/h‐BN ceramic composites meet the mechanical properties and biocompatibility requirements necessary for bone tissue applications, indicating promising potential in the field of bone tissue engineering.

Construction of a PEGDA/chitosan hydrogel incorporating mineralized copper-doped mesoporous silica nanospheres for accelerated bone regeneration

Hydrogels, integrating diverse biocompatible materials, have emerged as promising candidates for bone repair applications. This study presents a double network hydrogel designed for bone tissue engineering, combining poly(ethylene glycol) diacrylate (PEGDA) and chitosan (CS) crosslinked through UV polymerization and ionic crosslinking. Concurrently, copper-doped mesoporous silica nanospheres (Cu-MSNs) were synthesized using a one-pot method. Cu-MSNs underwent additional modification through in-situ biomineralization, resulting in the formation of an apatite layer. Polydopamine was employed to facilitate the deposition of Calcium (Ca) and Phosphate (P) ions on the surface of Cu-MSNs (Cu-MSNs/PDA@CaP). Composite hydrogels were created by integrating varied concentrations of Cu-MSNs/PDA@CaP (25, 50, 100, 150, 200 μg/mL). Characterization unveiled distinctive interconnected porous structures within the composite hydrogel, showcasing a notable 169.6 % enhancement in compressive stress (elevating from 89.01 to 240.19 kPa) compared to pure PEGDA. In vitro biocompatibility experiments illustrated that the composite hydrogel maintained elevated cell viability (up to 106.6 %) and facilitated rapid cell proliferation over 7 days. The hydrogel demonstrated a substantial 57.58 % rise in ALP expression and a surprising 235.27 % increase in ARS staining. Moreover, it significantly enhanced the expression of crucial osteogenic genes, such as run-related transcription factors 2 (RUNX2), collagen 1a1 (Col1a1), and secreted phosphoprotein 1 (Spp1), establishing it as a promising scaffold for bone regeneration. This study shows how Cu-MSNs/PDA@CaP were successfully integrated into a double network hydrogel, resulting in a composite material with good biological responses. Due to its improved characteristics, this composite hydrogel holds the potential for advancing bone regeneration procedures.

Photopolymerization of ceramic/zeolite reinforced photopolymers: Towards 3D/4D printing and gas adsorption applications

Normally, 3D printed objects via photopolymerization usually don’t have fully optimized mechanical properties and functions. In this context, the addition of single filler usually can improve these properties through the access to composite materials. However, the addition of filler inevitably has a negative influence on the light penetration inside the composites strongly reducing the depth of cure. Hence, the fabrications of photo-composites based on a combination of two inorganic fillers (alumina Al2O3 and zeolite LTA-5A) are reported in this work. Compared to pure poly(ethylene glycol) diacrylate (PEGDA) and its other corresponding single filler-based composites, PEGDA with 25 wt% LTA-5A and 25 wt% Al2O3-200 had several improved properties: better depth of cure (DOC), good mechanical properties (the storage modulus, tensile strength, the Young’s modulus). Direct laser write (DLW) was used to manufacture 3D patterns and 3D cross-shaped objects with good resolution. Under the hydrothermal stimuli, a 4D printing behavior (reversible shape change) was observed on the 3D cross-shaped objects. In addition, the 3D object with the condition of 4D printing had the ability of withstand a heavy stuff (the mass difference was more than 100 times). This is the first time to report the fabrication of the double filler-based (50 wt%) composite (ceramic and zeolite) with 4D printing behavior and good mechanical properties. Interestingly, calcinated composites had a certain structure strength and good CO2 adsorption performance. Therefore, this work not only paves the way for the investigation of photo-composites filled with multiple fillers combinations (how to improve the mechanical properties and keep good depth of cure for composites via photopolymerization), but also shows us the potential applications in the field of 3D/4D printing, microlithography and functional composites.

SLA-3d printing and compressive strength of PEGDA/nHAP biomaterials

Herein, poly (ethylene glycol) diacrylate (PEGDA)/nanohydroxyapatite (nHAP) biomaterials were prepared by stereolithography (SLA), rendering optimal compressive strength. PEGDA and photoinitiator I2959 were mechanically mixed with bioceramic nHAP to prepare a paste with simple composition, suitable viscosity, and excellent photocurable ability. The content of the photoinitiator in the paste was determined by the cytotoxicity of cured samples. Then, the solid content of paste and processing parameters were optimized by a uniform design experiment method according to the curing characteristics of PEGDA/nHAP paste and compressive strength of PEGDA/nHAP printed specimens. As a result, the minimum cured width of a single line of PEGDA/nHAP paste reached 65 μm on the XY plane, mainly influenced by laser power. The minimum cured depth of PEGDA/nHAP paste was found to be 150 μm, which was influenced by hatch spacing. The compressive strength of PEGDA/nHAP-printed specimens reached a maximum of 61.0 ± 3.9 MPa, which was about 1700% higher than pure PEGDA (3.6 ± 0.9 MPa). SLA-prepared PEGDA/nHAP biomaterials can meet compressive strength requirements of bone tissue (2–80 MPa), showing promise in the field of bone regeneration.

Facile Microfluidic Fabrication of Biocompatible Hydrogel Microspheres in a Novel Microfluidic Device.

Poly(ethylene glycol) diacrylate (PEGDA) microgels with tuneable size and porosity find applications as extracellular matrix mimics for tissue-engineering scaffolds, biosensors, and drug carriers. Monodispersed PEGDA microgels were produced by modular droplet microfluidics using the dispersed phase with 49–99 wt% PEGDA, 1 wt% Darocur 2959, and 0–50 wt% water, while the continuous phase was 3.5 wt% silicone-based surfactant dissolved in silicone oil. Pure PEGDA droplets were fully cured within 60 s at the UV light intensity of 75 mW/cm2. The droplets with higher water content required more time for curing. Due to oxygen inhibition, the polymerisation started in the droplet centre and advanced towards the edge, leading to a temporary solid core/liquid shell morphology, confirmed by tracking the Brownian motion of fluorescent latex nanoparticles within a droplet. A volumetric shrinkage during polymerisation was 1–4% for pure PEGDA droplets and 20–32% for the droplets containing 10–40 wt% water. The particle volume increased by 36–50% after swelling in deionised water. The surface smoothness and sphericity of the particles decreased with increasing water content in the dispersed phase. The porosity of swollen particles was controlled from 29.7% to 41.6% by changing the water content in the dispersed phase from 10 wt% to 40 wt%.

Photopolymerization of Zeolite Filler‐Based Composites for Potential 3D Printing Application and Gas Adsorption Applications

AbstractIn recent years, photopolymerization has been found wide applications in industry and daily life, while many defective properties of polymers limit their development, including compressive strength, mechanical properties, and functions. Furthermore, zeolites are microporous solids with many industrial applications. As fillers they can improve mechanical properties of zeolite/polymer composite and transfer their properties to composites. Here the fabrication is reported of composites with very high filler contents (80–95 wt%) under mild photopolymerization conditions (visible LED light irradiation, room temperature, under air). Compared to pure poly(ethylene glycol) diacrylate (PEGDA) polymer, mechanical properties have been greatly improved, and the storage modulus increased by nearly 20‐fold compared to that of pure polymer. After debinding/sintering of composites by high temperature treatment, zeolite porosity is preserved with good adsorption capacities. Some step‐like object with 3D structure is also obtained by an original 3D printing technique noted “layer by layer molding/curing.” Hence, as a great breakthrough, this work is expected to lead to a valuable development in the field of photopolymerization in quite highly filled composites. This also will expand their potential applications for 3D printing in the fields of high‐performance lightweight materials and adsorption, and opens the door to a new process of zeolite shaping.

Disclosing the Role of Defect‐Engineered Metal–Organic Frameworks in Mixed Matrix Membranes for Efficient CO2 Separation: A Joint Experimental‐Computational Exploration

AbstractIncorporation of defects in metal–organic frameworks (MOFs) offers new opportunities for manipulating their microporosity and functionalities. The so‐called “defect engineering” has great potential to tailor the mass transport properties in MOF/polymer mixed matrix membranes (MMMs) for challenging separation applications, for example, CO2 capture. This study first investigates the impact of MOF defects on the membrane properties of the resultant MOF/polymer MMMs for CO2 separation. Highly porous defect‐engineered UiO‐66 nanoparticles are successfully synthesized and incorporated into a CO2‐philic crosslinked poly(ethylene glycol) diacrylate (PEGDA) matrix. A thorough joint experimental/simulation characterization reveals that defect‐engineered UiO‐66/PEGDA MMMs exhibit nearly identical filler–matrix interfacial properties regardless of the defect concentrations of their parental UiO‐66 filler. In addition, non‐equilibrium molecular dynamics simulations in tandem with gas transport studies disclose that the defects in MOFs provide the MMMs with ultrafast transport pathways mainly governed by diffusivity selectivity. Ultimately, MMMs containing the most defective UiO‐66 show the most enhanced CO2/N2 separation performance—CO2 permeability = 470 Barrer (four times higher than pure PEGDA) and maintains CO2/N2 selectivity = 41—which overcomes the trade‐off limitation in pure polymers. The results emphasize that defect engineering in MOFs would mark a new milestone for the future development of optimized MMMs.

Azido-functionalized gelatin via direct conversion of lysine amino groups by diazo transfer as a building block for biofunctional hydrogels.

Gelatin is one of the most prominent biopolymers in biomedical material research and development. It is frequently used in hybrid hydrogels, which combine the advantageous properties of bio-based and synthetic polymers. To prevent the biological component from leaching out of the hydrogel, the biomolecules can be equipped with azides. Those groups can be used to immobilize gelatin covalently in hydrogels by the highly selective and specific azide-alkyne cycloaddition. In this contribution, we functionalized gelatin with azides at its lysine residues by diazo transfer, which offers the great advantage of only minimal side-chain extension. Approximately 84-90% of the amino groups are modified as shown by 1 H-NMR spectroscopy, 2,4,6-trinitrobenzenesulfonic acid assay as well as Fourier-transform infrared spectroscopy, rheology, and the determination of the isoelectric point. Furthermore, the azido-functional gelatin is incorporated into hydrogels based on poly(ethylene glycol) diacrylate (PEG-DA) at different concentrations (0.6, 3.0, and 5.5%). All hydrogels were classified as noncyctotoxic with significantly enhanced cell adhesion of human fibroblasts on their surfaces compared to pure PEG-DA hydrogels. Thus, the new gelatin derivative is found to be a very promising building block for tailoring the bioactivity of materials.

Silk Sericin Semi-interpenetrating Network Hydrogels Based on PEG-Diacrylate for Wound Healing Treatment

Silk sericin (SS) from the Bombyx mori silk cocoons has received much attention from biomedical scientists due to its outstanding properties, such as antioxidant, antibacterial, UV-resistant, and ability to release moisturizing factors. Unmodified SS does not self-assemble strongly enough to be used as a hydrogel wound dressing. Therefore, there is a need for suitable stabilization techniques to interlink the SS peptide chains or strengthen their structural cohesion. Here, we reported a method to form a silk semi-interpenetrating network (semi-IPN) structure through reacting with the short-chain poly(ethylene glycol) diacrylate (PEGDA) in the presence of a redox pair. Various hydrogels were prepared in aqueous media at the final SS/PEGDA weight percentages of 8/92, 15/85, and 20/80. Results indicated that all semi-IPN samples underwent a sol-gel transition within 70 min. The equilibrium water content (EWC) for all samples was found to be in the range of 70-80%, depending on the PEGDA content. Both the gelation time and the sol fraction decreased with the increased PEGDA content. This was due to the tightened network structure formed within the hydrogel matrices. Among all hydrogel samples, the 15/85 (SS/PEGDA) hydrogel displayed the maximum compressive strength (0.66 MPa) and strain (7.15%), higher than those of pure PEGDA. This implied a well-balanced molecular interaction within the SS/PEGDA/water systems. Based on the direct and indirect MTS assay, the 15/85 hydrogel showed excellent in vitro biocompatibility towards human dermal fibroblasts, representing a promising material for biomedical wound dressing in the future. A formation of a semi-IPN structure has thus proved to be one of the best strategies to extend a practical limit of using SS hydrogels for wound healing treatment or other biomedical hydrogel matrices in the future.

Covalent incorporation of tobacco mosaic virus increases the stiffness of poly(ethylene glycol) diacrylate hydrogels.

Hydrogels are versatile materials, finding applications as adsorbers, supports for biosensors and biocatalysts or as scaffolds for tissue engineering. A frequently used building block for chemically cross-linked hydrogels is poly(ethylene glycol) diacrylate (PEG-DA). However, after curing, PEG-DA hydrogels cannot be functionalized easily. In this contribution, the stiff, rod-like tobacco mosaic virus (TMV) is investigated as a functional additive to PEG-DA hydrogels. TMV consists of more than 2000 identical coat proteins and can therefore present more than 2000 functional sites per TMV available for coupling, and thus has been used as a template or building block for nano-scaled hybrid materials for many years. Here, PEG-DA (Mn = 700 g mol−1) hydrogels are combined with a thiol-group presenting TMV mutant (TMVCys). By covalent coupling of TMVCys into the hydrogel matrix via the thiol-Michael reaction, the storage modulus of the hydrogels is increased compared to pure PEG-DA hydrogels and to hydrogels containing wildtype TMV (wt-TMV) which is not coupled covalently into the hydrogel matrix. In contrast, the swelling behaviour of the hydrogels is not altered by TMVCys or wt-TMV. Transmission electron microscopy reveals that the TMV particles are well dispersed in the hydrogels without any large aggregates. These findings give rise to the conclusion that well-defined hydrogels were obtained which offer the possibility to use the incorporated TMV as multivalent carrier templates e.g. for enzymes in future studies.

Physically and chemically gelling hydrogel formulations based on poly(ethylene glycol) diacrylate and Poloxamer 407

Poloxamer 407 (P407) and poly (ethylene glycol) diacrylate (PEG-DA) are well-characterized building blocks for physical and chemical hydrogels, respectively. P407 physical hydrogels alone can be used as injectable hydrogels, but lack mechanical stability. In this contribution, PEG-DA was added to physically gelling P407 solutions in order to introduce chemical curing ability. The resulting hydrogel formulations containing P407, PEG-DA (Mn = 700 g mol−1) and the photoinitiator 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one (Irgacure 2959) were characterized concerning their physical and chemical gelling behavior. Upon addition of PEG-DA to P407 solutions, their gel transition temperature Tgel was altered and could be adjusted between 10 °C and 39 °C. At P407 concentrations cPolox of <22.5 wt.-%, Tgel increased compared to P407 solutions by adding PEG-DA. At cPolox>22.5 wt.-% Tgel decreased. The different behavior at different cPolox could be explained by a combination of a decrease of P407 micelle size as well as a decrease of the critical mizellization temperature of P407 upon PEG-DA addition. Chemical gelation of the formulations was investigated by real-time FT-IR spectroscopy combined with photorheology as well as by the equilibrium degree of swelling and shear moduli of the cured hydrogels. Hydrogel curing was significantly faster without altering the double bond conversion when P407 was present in the formulations, probably due to prearrangement of the double bonds. The shear moduli and equilibrium degrees of swelling of the cured hydrogels could be adjusted by the PEG-DA concentration in the formulation, similar to pure PEG-DA hydrogels. The hydrogel formulations presented are promising candidates for injectable hydrogels with chemical curing ability.

Water-Hydrogel Binding Affinity Modulates Freeze-Drying-Induced Micropore Architecture and Skeletal Myotube Formation.

Freeze-dried hydrogels are increasingly used to create 3D interconnected micropores that facilitate biomolecular and cellular transports. However, freeze-drying is often plagued by variance in micropore architecture based on polymer choice. We hypothesized that water-polymer binding affinity plays a significant role in sizes and numbers of micropores formed through freeze-drying, influencing cell-derived tissue quality. Poly(ethylene glycol)diacrylate (PEGDA) hydrogels with alginate methacrylate (AM) were used due to AM's higher binding affinity for water than PEGDA. PEGDA-AM hydrogels with larger AM concentrations resulted in larger sizes and numbers of micropores than pure PEGDA hydrogels, attributed to the increased mass of water binding to the PEGDA-AM gel. Skeletal myoblasts loaded in microporous PEGDA-AM hydrogels were active to produce 3D muscle-like tissue, while those loaded in pure PEGDA gels were localized on the gel surface. We propose that this study will be broadly useful in designing and improving the performance of various microporous gels.

Tuning mechanical performance of poly(ethylene glycol) and agarose interpenetrating network hydrogels for cartilage tissue engineering

Hydrogels are attractive for tissue engineering applications due to their incredible versatility, but they can be limited in cartilage tissue engineering applications due to inadequate mechanical performance. In an effort to address this limitation, our team previously reported the drastic improvement in the mechanical performance of interpenetrating networks (IPNs) of poly(ethylene glycol) diacrylate (PEG-DA) and agarose relative to pure PEG-DA and agarose networks. The goal of the current study was specifically to determine the relative importance of PEG-DA concentration, agarose concentration, and PEG-DA molecular weight in controlling mechanical performance, swelling characteristics, and network parameters. IPNs consistently had compressive and shear moduli greater than the additive sum of either single network when compared to pure PEG-DA gels with a similar PEG-DA content. IPNs withstood a maximum stress of up to 4.0 MPa in unconfined compression, with increased PEG-DA molecular weight being the greatest contributing factor to improved failure properties. However, aside from failure properties, PEG-DA concentration was the most influential factor for the large majority of properties. Increasing the agarose and PEG-DA concentrations as well as the PEG-DA molecular weight of agarose/PEG-DA IPNs and pure PEG-DA gels improved moduli and maximum stresses by as much as an order of magnitude or greater compared to pure PEG-DA gels in our previous studies. Although the viability of encapsulated chondrocytes was not significantly affected by IPN formulation, glycosaminoglycan (GAG) content was significantly influenced, with a 12-fold increase over a three-week period in gels with a lower PEG-DA concentration. These results suggest that mechanical performance of IPNs may be tuned with partial but not complete independence from biological performance of encapsulated cells.

Tuning the dependency between stiffness and permeability of a cell encapsulating hydrogel with hydrophilic pendant chains

The mechanical stiffness of a hydrogel plays a significant role in regulating the phenotype of cells that adhere to its surface. However, the effect of hydrogel stiffness on cells cultured within its matrix is not well understood, because of the intrinsic inverse dependency between the permeability and stiffness of hydrogels. This study therefore presents an advanced biomaterial design strategy to decrease the inverse dependency between permeability and stiffness of a cell encapsulating hydrogel. Hydrogels were made by cross-linking poly(ethylene glycol) diacrylate (PEGDA) and poly(ethylene glycol) monoacrylate (PEGMA), with PEGMA acting as a pendant polymer chain. Increasing the mass fraction of PEGMA while keeping the total polymer concentration constant led to a decrease in the elastic modulus ( E) of the hydrogel, but caused a minimal increase in the swelling ratio ( Q). The size and hydrophobicity of the end groups of pendant PEG chains further fine tuned the dependency between Q and E of the hydrogel. Pure PEGDA hydrogels with varying molecular weights, which show the same range of E but a much greater range of Q, were used as a control. Fibroblasts encapsulated in PEGDA–PEGMA hydrogels displayed more significant biphasic dependencies of cell viability and vascular endothelial growth factor (VEGF) expression on E than those encapsulated in pure PEGDA hydrogels, which were greatly influenced by Q. Overall, the hydrogel design strategy presented in this study will be highly useful to better regulate the phenotype and ultimately improve the therapeutic efficacy of a wide array of cells used in various biology studies and clinical settings.

Flexural characterization of cell encapsulated PEGDA hydrogels with applications for tissue engineered heart valves

The limitations of the current clinical options for valve replacements have inspired the development of enabling technologies to create a tissue engineered heart valve (TEHV). Poly(ethylene glycol) diacrylate (PEGDA) hydrogel scaffolds permit greater biological and biomechanical customization than do non-woven mesh scaffold technologies. However, the material characterization of PEGDA hydrogels has been predominantly limited to compression and tension, as opposed to bending. Since large flexural deformations result in points of maximum stress in native valves as well as TEHVs, it is crucial to evaluate any potential scaffold material in this mode. The effect of formulation parameters on the bending mechanics of cell-seeded PEGDA hydrogels were investigated with a custom designed bending tester. Three molecular weights (3.4, 6, and 8 kDa) and three weight fractions (5%, 10%, and 15%, w/v) were subjected to three-point bending tests and the flexural stiffness was calculated. Manipulating the composition of the hydrogels resulted in flexural stiffnesses comparable with native tissues (15–220 kPa) with varied mesh sizes and swelling ratios. Hydrogels containing encapsulated valve cells, methacrylated heparin (Hep-MA), or both were substantially less stiff than acellular hydrogels. In conclusion, PEGDA hydrogels are an attractive potential scaffold system for TEHVs because they are not only cytocompatible and modifiable but can also withstand bending deformations. These studies are the first to explore the encapsulation of valvular interstitial cells in pure PEGDA hydrogels as well as to investigate the bending properties of PEGDA gels.

Solubility and partial molar volume of carbon dioxide and ethane in crosslinked poly(ethylene oxide) copolymer

AbstractExperimental solubility and sorptive dilation data are reported for carbon dioxide and ethane in a crosslinked poly(ethylene oxide) (XLPEO) rubbery copolymer. Five different temperatures (253 ≤ T(K) ≤ 308) were considered, with a maximum gas pressure of 2.09 MPa (20.6 atm). The polymer was prepared by photopolymerization of a solution containing 70 wt % poly(ethylene glycol) methyl ether acrylate (PEGMEA) and 30 wt % poly(ethylene glycol) diacrylate (PEGDA). Sorption isotherms were described by the Flory‐Huggins model. For each gas, the Flory‐Huggins interaction parameter was a decreasing function of temperature and did not show a composition dependence. Dilation and sorption data were combined to calculate the partial molar volume (PMV) of the gases in the polymer, which was an increasing function of temperature. Based on a comparison with literature data for a XLPEO homopolymer prepared from pure PEGDA over the same range of operating conditions, an effect of the network composition on both gas solubility and PMV was found. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 456–468, 2010

Impregnation of Tubular Self-Assemblies into Dextran Hydrogels

Amine groups are the building units of proteins. The incorporation of amine groups into polyethylene glycol diacrylate (PEGDA) hydrogel through dextran-allyl isocyanate-ethylamine (Dex-AE) enhances sustained protein release by introducing effective interactions. To investigate such an interaction effect and to improve protein release, we impregnated self-assembled tubular structures from dextran-bromoethylamine (Dex-BH) and dextran-chloroacetic acid (Dex-CA) into Dex-AE/PEGDA hydrogel. The morphology data obtained from scanning electron microscopy (SEM) reveal that pure PEGDA hydrogel had no effect on the distribution of the self-assembled tubules; the introduction of Dex-AE brought about the dispersion of these tubules, and an increase in Dex-AE content led to more evenly distributed structures. Moreover, the implantation of the self-assembled tubules had no distinct effect on the swelling capacity of the hybrid self-assembly embedded hydrogels. The in vitro albumin release study was carried out in a pH 7.4 buffer solution; the results show that the implantation of the self-assembly into the hydrogels reduced the burst release and prolonged the protein release time. These findings demonstrate that the impregnation of tubular self-assembly into hydrogel makes the hybrid hydrogel an excellent protein delivery system.

Synthesis, characterization of biodegradable dextran–allyl isocyanate–ethylamine/polyethylene glycol–diacrylate hydrogels and their in vitro release of albumin

Based on dextran–allyl isocyanate–ethylamine (Dex-AE) and polyethylene glycol–diacrylate (PEGDA), a pH sensitive biodegradable hydrogel with improved protein release was prepared through UV photo-crosslinking. The Dex-AE precursor was prepared through a two-step chemical modification and characterized by FT-IR and 1H NMR. The effects of reaction conditions on the synthesis of Dex-AE were studied. The interior morphology data by scanning electron microscopy (SEM) revealed that an increase in Dex-AE content led to an initial decrease in pore size of the microstructure of the Dex-AE/PEGDA hydrogels, but a further increase in Dex-AE content resulted in a relatively looser network structure. The swelling data indicated that the swelling ratio depended on the precursor feed ratio and was correlated to the morphology of the microporous network structure. The pH sensitive property of the Dex-AE/PEGDA hydrogels was studied in different pH buffer solutions and was found that these hydrogels were pH sensitive due to the presence of ample pendant amino groups. The ionic strength data demonstrated that the Dex-AE/PEGDA hydrogels exhibit the highest swelling ratio in pure water, but the swelling ratio became lower as the ionic strength of the media increased. The in vitro albumin release from these hydrogels was examined in different pH (3.0, 7.4) buffer solutions. Both the protein loading and release data indicated that the Dex-AE/PEGDA hydrogels had more protein loading and sustained release capability than pure PEGDA hydrogel, and this ability increased as the Dex-AE composition increased; the Dex-AE/PEGDA hydrogel also showed a faster BSA release in a lower pH than a higher pH medium.

Characterization of UV-cured gel polymer electrolytes for rechargeable lithium batteries

Novel ultraviolet (UV)-cured gel polymer electrolytes based on polyethyleneglycol diacrylate (PEGDA) oligomer and polyvinylidene fluoride (PVdF) are prepared and characterized. UV-curing of PEGDA oligomer containing PVdF and ethylene carbonate (EC)-based liquid electrolyte yields chemically and physically cross-linked PEGDA/PVdF blend gel electrolytes. PEGDA/PVdF blend films show much higher mechanical properties and electrolyte liquid retention than pure PEGDA film. The ionic conductivity ( σ) of a PEGDA/PVdF (5/5) blend electrolyte reaches about 4 mS cm −1 at ambient temperature and is as high as 1 mS cm −1 at 0 °C. All the blend electrolytes are electrochemically stable up to 4.6 V versus Li/Li +. The cation transference number ( t +) measured by dc micropolarization exceeds 0.5 at room temperature. Li/(PEGDA/PVdF)/LiCoO 2 cells ( 2 cm×2 cm) retains >91% of its initial discharge capacity after 50 cycles at the C/3 rate (2 mA cm −2) and delivers about 70% of full capacity with an average load voltage of 3.6 V at the C/1 rate. Cell performance is stable up to 80 °C because PVdF chains might be stabilized by entanglement with the chemically cross-linked PEGDA network structure.