Photocrosslinked Poly(ethylene Glycol) Diacrylate Research Articles

3D printed bio-ceramic loaded PEGDA/vitreous carbon composite: Fabrication, characterization, and life cycle assessment

Stereolithography (SLA) is gaining vast popularity in the development of three-dimensional parts with customized materials for tissue engineering applications. Consequently, developing customized materials like bio-composites (bio-polymers and bio-ceramics) is the basic pillar that meets the application requirement. Photo-crosslinkable poly(ethylene glycol) diacrylate (PEGDA) has outstanding biocompatibility and biophysical properties for tissue engineering. But, because of its poor mechanical properties, its scope is limited to load-bearing applications. This research aims to enhance the mechanical and tribological properties of PEGDA by reinforcing Vitreous Carbon (VC) bioceramic. Therefore, 1 to 5 wt % of VC have been added in PEGDA and developed novel PEGDA/VC composite resins for SLA. The rheological and sedimentation test have been performed to check the suitability for SLA printing. Afterward, printed materials have been characterized by fourier transform infrared spectrometer, X-ray diffraction, thermogravimetric analysis, optical profilometer, and scanning electron microscope. Moreover, tensile compression, flexural, and tribological properties have been evaluated. It was found that the addition of VC in PEGDA enhanced its mechanical, thermal, and tribological properties. Besides, a life cycle assessment of materials and energy resources in SLA process has been performed to investigate the environmental impact.

Preparation and characterization of pH-sensitive hydrogels from photo-crosslinked poly(ethylene glycol) diacrylate incorporating titanium dioxide

Abstract The purpose of the present investigation was to prepare pH-sensitive hydrogels from photo-crosslinked poly(ethylene glycol) diacrylate (PEG-DA). Rutile titanium dioxide (TiO2) was employed to modify the PEG-DA hydrogels. The rutile titanium dioxide (TiO2) nanoparticles were prepared by direct oxidation of titanium in the presence of polyethylene glycol (PEG) at high temperature. The nanoparticles were characterized by FT-IR, XRD and SEM. The influence of experimental conditions, such as pH, type and amount of photoinitiators on the release profiles of donepezil hydrochloride (active pharmaceutical ingredient for Alzheimer disease) from modified PEG-DA hydrogels, was investigated. The drug release processes were analyzed kinetically using zero-order, first-order, Hixson-Crowell and Peppas models.

Synthesis and Characterisation of Photocrosslinked poly(ethylene glycol) diacrylate Implants for Sustained Ocular Drug Delivery

PurposeTo investigate the sustained ocular delivery of small and large drug molecules from photocrosslinked poly(ethylene glycol) diacrylate (PEGDA) implants with varying pore forming agents.MethodsTriamcinolone acetonide and ovalbumin loaded photocrosslinked PEGDA implants, with or without pore-forming agents, were fabricated and characterised for chemical, mechanical, swelling, network parameters, as well as drug release and biocompatibility. HPLC-based analytical methods were employed for analysis of two molecules; ELISA was used to demonstrate bioactivity of ovalbumin.ResultsRegardless of PEGDA molecular weight or pore former composition all implants loaded with triamcinolone acetonide released significantly faster than those loaded with ovalbumin. Higher molecular weight PEGDA systems (700 Da) resulted in faster drug release of triamcinolone acetonide than their 250 Da counterpart. All ovalbumin released over the 56-day time period was found to be bioactive. Increasing PEGDA molecular weight resulted in increased system swelling, decreased crosslink density (Ve), increased polymer-water interaction parameter (χ), increased average molecular weight between crosslinks (Mc) and increased mesh size (ε). SEM studies showed the porosity of implants increased with increasing PEGDA molecular weight. Biocompatibility showed both PEGDA molecular weight implants were non-toxic when exposed to retinal epithelial cells over a 7-day period.ConclusionPhotocrosslinked PEGDA implant based systems are capable of controlled drug release of both small and large drug molecules through adaptations in the polymer system network. We are currently continuing evaluation of these systems as potential sustained drug delivery devices.

Biomimetically Reinforced Polyvinyl Alcohol-Based Hybrid Scaffolds for Cartilage Tissue Engineering.

Articular cartilage has a very limited regeneration capacity. Therefore, injury or degeneration of articular cartilage results in an inferior mechanical stability, load-bearing capacity, and lubrication capability. Here, we developed a biomimetic scaffold consisting of macroporous polyvinyl alcohol (PVA) sponges as a platform material for the incorporation of cell-embedded photocrosslinkable poly(ethylene glycol) diacrylate (PEGDA), PEGDA-methacrylated chondroitin sulfate (PEGDA-MeCS; PCS), or PEGDA-methacrylated hyaluronic acid (PEGDA-MeHA; PHA) within its pores to improve in vitro chondrocyte functions and subsequent in vivo ectopic cartilage tissue formation. Our findings demonstrated that chondrocytes encapsulated in PCS or PHA and loaded into macroporous PVA hybrid scaffolds maintained their physiological phenotypes during in vitro culture, as shown by the upregulation of various chondrogenic genes. Further, the cell-secreted extracellular matrix (ECM) improved the mechanical properties of the PVA-PCS and PVA-PHA hybrid scaffolds by 83.30% and 73.76%, respectively, compared to their acellular counterparts. After subcutaneous transplantation in vivo, chondrocytes on both PVA-PCS and PVA-PHA hybrid scaffolds significantly promoted ectopic cartilage tissue formation, which was confirmed by detecting cells positively stained with Safranin-O and for type II collagen. Consequently, the mechanical properties of the hybrid scaffolds were biomimetically reinforced by 80.53% and 210.74%, respectively, compared to their acellular counterparts. By enabling the recapitulation of biomimetically relevant structural and functional properties of articular cartilage and the regulation of in vivo mechanical reinforcement mediated by cell–matrix interactions, this biomimetic material offers an opportunity to control the desired mechanical properties of cell-laden scaffolds for cartilage tissue regeneration.

Capillary Network-Like Organization of Endothelial Cells in PEGDA Scaffolds Encoded with Angiogenic Signals via Triple Helical Hybridization.

Survival of tissue engineered constructs after implantation depends on proper vascularization. The differentiation of endothelial cells into mature microvasculature requires dynamic interactions between cells, scaffold, and growth factors, which are difficult to recapitulate in artificial systems. Previously, photocrosslinked poly(ethylene glycol) diacrylate (PEGDA) hydrogels displaying collagen mimetic peptides (CMPs), dubbed PEGDA‐CMP, that can be further conjugated with bioactive molecules via CMP‐CMP triple helix hybridization were reported. Here, it is shown that a bifunctional peptide featuring pro‐angiogenic domain mimicking vascular endothelial growth factor (VEGF) and a collagen mimetic domain that can fold into a triple helix conformation can hybridize with CMP side chains of the PEGDA‐CMP hydrogel, which results in presentation of insoluble VEGF‐like signals to endothelial cells. Presentation of VEGF‐like signals on the surface of micropatterned scaffolds in this way transforms cells from a quiescent state to elongated and aligned phenotype suggesting that this system could be used to engineer organized microvasculature. It is also shown that the pro‐angiogenic peptide, when applied topically in combination with modified dextran/PEGDA hydrogels, can enhance neovascularization of burn wounds in mice demonstrating the potential clinical use of CMP‐mediated matrix‐bound bioactive molecules for dermal injuries.

Structural Reinforcement of Cell-Laden Hydrogels with Microfabricated Three Dimensional Scaffolds.

Hydrogels commonly used in tissue engineering are mechanically soft, thus often display structural weakness. Herein, we introduce a strategy for enhancing the structural integrity and fracture toughness of cell-laden hydrogels by incorporating a three-dimensional (3D) microfabricated scaffold as a structural element. A digital micromirror device projection printing (DMD-PP) system, a rapid prototyping technology which employs a layer-by-layer stereolithographic approach, was utilized to efficiently fabricate 3D scaffolds made from photocrosslinkable poly(ethylene glycol) diacrylate (PEGDA). The scaffold was incorporated into a photocrosslinkable gelatin hydrogel by placing it in a pre-gel solution, and inducing in situ hydrogel formation. The resulting scaffold-reinforced hydrogels demonstrated significant increase in ultimate stress and provided structural support for weak hydrogels. In addition, the scaffold did not affect the rigidity of hydrogels, as it was not involved in the crosslinking reaction to form the hydrogel. Therefore, the presented approach could avoid inadvertent and undesired changes in the hydrogel rigidity which is a known regulator of cellular activities. Furthermore, the biocompatibility of scaffold-reinforced hydrogels was confirmed by evaluating the viability and proliferation of encapsulated fibroblasts. Overall, the strategy of incorporating 3D scaffolds into hydrogels as structural reinforcements presented in this study will be highly useful for enhancing the mechanical toughness of hydrogels for various tissue engineering applications.

Cell-based high-throughput odorant screening system through visualization on a microwell array

The development of a cell-based high-throughput screening system has attracted much attention from researchers who study drug screening mechanisms and characterization of G-protein coupled receptors (GPCRs). Although olfactory receptors (ORs) constitute the largest group of GPCRs that play a critical role recognizing and discriminating odorants, only a few ORs have been characterized, and most remain orphan. The conventional cell-based assay system for characterizing GPCRs, including ORs, is very laborious, time consuming, and requires an expensive assay system. In this study, we developed a simple, low-cost miniaturized odorant screening method by combining Micro-Electro-Mechanical system (MEMs) technique and visualization technique for detecting an odorant response. We fabricated PEG microwell from a photocrosslinkable polyethylene glycol diacrylate (PEGDA) solution and applied it to cell culture and a reverse transfection platform for cell-based high-throughput screening. For the first time, the olfactory receptors were expressed on the microwell platform using reverse transfection technique. The various olfactory receptors can be expressed simultaneously using this technique and the microwell spotted with olfactory receptor genes can be used as a high-throughput screening platform. The odorant response was detected via fluorescence analysis on the microwell using a cAMP response element (CRE) reporter assay. We tested this platform using four de-orphaned ORs. This new cell-based screening method not only reduced numerous time-consuming steps but also allowed for simple, efficient, and quantitative screening and patterning of large numbers of GPCRs including ORs, which can help to visualize the OR response to odorants on a microwell.

Quantitative optimization of solid freeform deposition of aqueous hydrogels

Many soft tissues exhibit complex anatomical geometry that is challenging to replicate for regenerative medicine applications. Solid freeform fabrication (SFF) has emerged as an attractive approach for creating 3D tissues, but a detailed understanding of how specific fabrication parameters affect accuracy and viability has not been established to date. In this study, we evaluate the effects of printing parameters of the Fab@Home 3D printing system on accuracy using alginate, photocrosslinkable polyethylene-glycol diacrylate (PEG-DA) and gelatin as commonly used model hydrogel materials. Print accuracy and resolution along the length, width and height were determined based on quantitative image analysis. The effects of extrusion parameters on cell viability were assessed using porcine aortic valve interstitial cells (PAVIC) as a model cell type. We observed that pressure, pathheight and pathspace all significantly affected print accuracy and resolution. Printing conditions did not affect PAVIC viability within the ranges applied. We predicted that optimal pressure, pathheight and pathspace values would be increased linearly with increasing nozzle diameter, and we confirmed that the predicted values generate accurate 3D geometries while poorly chosen parameters yield inaccurate, unpredictable geometries. This systematic optimization strategy therefore improves the accuracy of 3D printing platforms for biofabrication and tissue engineering applications.

Encoding cell-instructive cues to PEG-based hydrogels via triple helical peptide assembly

Effective synthetic tissue engineering scaffolds mimic the structure and composition of natural extracellular matrix (ECM) to promote optimal cellular adhesion, proliferation, and differentiation. Among many proteins of the ECM, collagen and fibronectin are known to play a key role in the scaffold's structural integrity as well as its ability to support cell adhesion. Here, we present photocrosslinked poly(ethylene glycol) diacrylate (PEGDA) hydrogels displaying collagen mimetic peptides (CMPs) that can be further conjugated to bioactive molecules via CMP-CMP triple helix association. Pre-formed PEGDA-CMP hydrogels can be encoded with varying concentration of cell-signaling CMP-RGD peptides similar to cell adhesive fibronectin decorating the collagen fibrous network by non-covalent binding. Furthermore, the triple helix mediated encoding allows facile generation of spatial gradients and patterns of cell-instructive cues across the cell scaffold that simulate distribution of insoluble factors in the natural ECM.

Quasi-solid polymer electrolytes using photo-cross-linked polymers. Lithium and divalent cation conductors and their applications

In this report, we will present the results on the photo-cross-linked poly-(ethylene glycol) diacrylate (PEGDA) based quasi-solid, i.e. gel, polymer electrolyte systems with lithium, magnesium and zinc trifluoromethanesulfonates [triflate; M n (CF 3 SO 3 ) n ] and their preliminary applications to primary cells. The Celgard® membrane-impregnated electrolytes were prepared in the same manner as Abraham et al. [K.M. Abraham, M. Alamgir, D.K. Hoffman, J. Electrochem. Soc. 142 (1995) 683]. The precursor solutions were composed of metal triflates, ethylene carbonate, propylene carbonate, and tetraethylene glycol diacrylate. The Celgard® #3401 membrane was soaked overnight in the precursor solution, then clamped between two Pyrex glass plates and irradiated with UV light to form a gel electrolyte. The maxima of the conductivity obtained were 4.5 × 10 -4 S cm -1 at 12 mol% for LiCF 3 SO 3 , 1.7 × 10 -4 S cm -1 at 1 mol% for Mg(CF 3 SO 3 ) 2 , and 2.1 × 10 -4 S cm -1 at 4 mol% for Zn(CF 3 SO 3 ) 2 system, respectively. The Arrhenius plots of the conductivities are almost linear between 268 and 338 K with 15-25 kJ/mol of activation energy for conduction. The cell, Li|LiCF 3 SO 3 -SPE + Celgard® #3401|(CH 3 ) 4 NI 5 + acetylene black, showed 2.86 V of OCV and could discharge up to 25% with respect to the cathode active material at a discharging current of 0.075 mA/cm 2 .