Recombinant collagen coating 3D printed PEGDA hydrogel tube loading with differentiable BMSCs to repair bile duct injury.

Bile duct injury presents a significant clinical challenge following hepatobiliary surgery, necessitating advancements in the repair of damaged bile ducts is a persistent issue in biliary surgery. 3D printed tubular scaffolds have emerged as a promising approach for the repair of ductal tissues, yet the development of scaffolds that balance exceptional mechanical properties with biocompatibility remains an ongoing challenge. This study introduces a novel, bio-fabricated bilayer bile duct scaffold using a 3D printing technique. The scaffold comprises an inner layer of polyethylene glycol diacrylate (PEGDA) to provide high mechanical strength, and an outer layer of biocompatible, methacryloylated recombinant collagen type III (rColMA) loaded with basic fibroblast growth factor (bFGF)-encapsulated liposomes (bFGF@Lip). This design enables the controlled release of bFGF, creating an optimal environment for the growth and differentiation of bone marrow mesenchymal stem cells (BMSCs) into cholangiocyte-like cells. These cells are instrumental in the regeneration of bile duct tissues, evidenced by the pronounced expression of cholangiocyte differentiation markers CK19 and CFTR. The PEGDA//rColMA/bFGF@Lip bilayer bile duct scaffold can well simulate the bile duct structure, and the outer rColMA/bFGF@Lip hydrogel can well promote the growth and differentiation of BMSCs into bile duct epithelial cells. In vivo experiments showed that the scaffold did not cause cholestasis in the body. This new in vitro pre-differentiated active 3D printed scaffold provides new ideas for the study of bile duct tissue replacement.

Polyethylene Glycol Cross-Linked Hydrogel for Drug Absorption Properties.

Three-dimensional polymeric networks called hydrogels have drawn a lot of interest in a variety of biomedical applications because of their distinctive qualities, like high water content and biocompatibility. Hydrogels can be strengthened mechanically and become more stable via cross-linking. In this study, we described the synthesis and characterization of a cross-linked hydrogel made of polyethylene glycol (PEG) capable of absorbing drug. The hydrogel was created by using a polymerization procedure to cross-link PEG chains. In order to allay this worry, we added particular functional groups to the hydrogel matrix that had a strong affinity for glutaraldehyde. These functional groups made it easier for excess glutaraldehyde to be absorbed and sequestered inside the hydrogel, lowering its cytotoxic potential. After incubation with the hydrogel, the residual glutaraldehyde concentration in solution was measured in order to assess the glutaraldehyde absorption potential.

Gold-Hydrogel Nanocomposites for High-Resolution Laser-Based 3D Printing of Scaffolds with SERS-Sensing Properties.

Although visible light-based stereolithography (SLA) represents an affordable technology for the rapid prototyping of 3D scaffolds for in vitro support of cells, its potential could be limited by the lack of functional photocurable biomaterials that can be SLA-structured at micrometric resolution. Even if innovative photocomposites showing biomimetic, bioactive, or biosensing properties have been engineered by loading inorganic particles into photopolymer matrices, main examples rely on UV-assisted extrusion-based low-resolution processes. Here, SLA-printable composites were obtained by mixing a polyethylene glycol diacrylate (PEGDA) hydrogel with multibranched gold nanoparticles (NPs). NPs were engineered to copolymerize with the PEGDA matrix by implementing a functionalization protocol involving covalent grafting of allylamine molecules that have C═C pendant moieties. The formulations of gold nanocomposites were tailored to achieve high-resolution fast prototyping of composite scaffolds via visible light-based SLA. Furthermore, it was demonstrated that, after mixing with a polymer and after laser structuring, gold NPs still retained their unique plasmonic properties and could be exploited for optical detection of analytes through surface-enhanced Raman spectroscopy (SERS). As a proof of concept, SERS-sensing performances of 3D printed plasmonic scaffolds were successfully demonstrated with a Raman probe molecule (e.g., 4-mercaptobenzoic acid) from the perspective of future extensions to real-time sensing of cell-specific markers released within cultures. Finally, biocompatibility tests preliminarily demonstrated that embedded NPs also played a key role by inducing physiological cell-cytoskeleton rearrangements, further confirming the potentialities of such hybrid nanocomposites as groundbreaking materials in laser-based bioprinting.

Nanosilicate-reinforced GelMA-PEGDA hydrogel promotes angiogenesis for bone regeneration.

Bone tissue engineering has emerged as a pivotal field addressing the critical clinical needs of bone fractures. This study focused on developing multi-composite hydrogels by synergizing biocompatible GelMA macromolecules with synthetic PEGDA and reinforcing them with nanosilicates (SN). The incorporation of SN introduces crucial trace elements such as silicon, magnesium, and lithium, promoting both angiogenesis and osteogenesis. Characterizations revealed that PEGDA significantly reinforced the composite hydrogels' stability, while SN further enhanced the mechanical integrity of the GelMA-PEGDA-SN (GPS) hydrogels. Cell studies designated that GPS improved cell proliferation and migration, angiogenic VEGF/eNOS expression and osteogenic differentiation. In vivo experiments showed that GPS hydrogels effectively enhanced calvarial bone healing, with the GPS-2 formulation (2 % SN) displaying superior bone coverage and increased vascular formation. Assessments of osteogenic formation and the angiogenic marker CD31 validated the comprehensive bone regeneration potential of GPS hydrogels. These findings highlight the significant promise of GPS hydrogels in fostering bone healing with promoted angiogenesis.

Anisotropic hydrogel scaffold by flow-induced stereolithography 3D printing technique.

Essential organs, such as the heart and liver, contain a unique porous network that allows oxygen and nutrients to be exchanged, with distinct random to ordered regions displaying varying degrees of strength. A novel technique, referred to here as flow-induced lithography, was developed. This technique generates tunable anisotropic three-dimensional (3D) structures. The ink for this bioprinting technique was made of titanium dioxide nanorods (Ti) and kaolinite nanoclay (KLT) dispersed in a GelMA/PEGDA polymeric suspension. By controlling the flow rate, aligned particle microstructures were achieved in the suspensions. The application of UV light to trigger the polymerization of the photoactive prepolymer freezes the oriented particles in the polymer network. Because the viability test was successful in shearing suspensions containing cells, the flow-induced lithography technique can be used with both acellular scaffolds and cell-laden structures. Fabricated hydrogels show outstanding mechanical properties resembling human tissues, as well as significant cell viability (> 95 %) over one week. As a result of this technique and the introduction of bio-ink, a novel approach has been pioneered for developing anisotropic tissue implants utilizing low-viscosity biomaterials.

Multiple Na+ transport pathways and interfacial compatibility enable high-capacity, room-temperature quasi-solid sodium batteries.

Sodium-metal batteries (SMBs) are ideal for large-scale energy storage due to their stable operation and high capacity. However, they have safety issues caused by severe dendrite growth and side reactions, particularly when using liquid electrolytes. Therefore, it is critically important to develop electrolytes with high ionic conductivity and improved safety that are non-flammable and resistant to dendrites. Here, we developed polymerized polyethylene glycol diacrylate (PEGDA)-modified poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) electrolytes (PPEs) with highly conductive sodium bis(trifluoromethanesulfonyl)imide and corrosion-inhibitive sodium bis(oxalato)borate salts for SMBs. Well-complexed PEGDA not only increases the amorphicity of the PVDF matrix, but also offers numerous Lewis basic sites through the polar groups of carbonyl and ether groups (i.e., electron donors). The presence of the Lewis basic sites facilitates the dissociation of sodium salt and transportation of Na+ within the PVDF matrix. This results in the generation of additional Na+ transport pathways, which can enhance the performance of the battery. Among PPEs, the optimized PPE-50 exhibits a high ionic conductivity of 3.42 × 10-4 S cm-1 and a mechanical strength of 14.0 MPa. A Na||Na symmetric cell with PPE-50 displays high stability at 0.2 mA cm-2 for 800 h. PPE-50 further displays high capacity, e.g., a Na3V2(PO4)3|PPE-50|Na battery delivers a decent discharge capacity of 101.5 mAh g-1 at 1.0C after 650 cycles. Our work demonstrates the development of high-performance quasi-solid polymer electrolytes with multiple transport pathways suitable for room-temperature SMBs.

Exploiting light-based 3D-printing for the fabrication of mechanically enhanced, patient-specific aortic grafts.

Despite polyester vascular grafts being routinely used in life-saving aortic aneurysm surgeries, they are less compliant than the healthy, native human aorta. This mismatch in mechanical behaviour has been associated with disruption of haemodynamics contributing to several long-term cardiovascular complications. Moreover, current fabrication approaches mean that opportunities to personalise grafts to the individual anatomical features are limited. Various modifications to graft design have been investigated to overcome such limitations; yet optimal graft functionality remains to be achieved. This study reports on the development and characterisation of an alternative vascular graft material. An alginate:PEGDA (AL:PE) interpenetrating polymer network (IPN) hydrogel has been produced with uniaxial tensile tests revealing similar strength and stiffness (0.39 ± 0.05 MPa and 1.61 ± 0.19 MPa, respectively) to the human aorta. Moreover, AL:PE tubular conduits of similar geometrical dimensions to segments of the aorta were produced, either via conventional moulding methods or stereolithography (SLA) 3D-printing. While both fabrication methods successfully demonstrated AL:PE hydrogel production, SLA 3D-printing was more easily adaptable to the fabrication of complex structures without the need of specific moulds or further post-processing. Additionally, most 3D-printed AL:PE hydrogel tubular conduits sustained, without failure, compression up to 50% their outer diameter and returned to their original shape upon load removal, thereby exhibiting promising behaviour that could withstand pulsatile pressure in vivo. Overall, these results suggest that this AL:PE IPN hydrogel formulation in combination with 3D-printing, has great potential for accelerating progress towards personalised and mechanically-matched aortic grafts.

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.

A 4D printed self-assembling PEGDA microscaffold fabricated by digital light processing for arthroscopic articular cartilage tissue engineering.

Articular cartilage in synovial joints such as the knee has limited capability to regenerate independently, and most clinical options for focal cartilage repair merely delay total joint replacement. Tissue engineering presents a repair strategy in which an injectable cell-laden scaffold material is used to reconstruct the joint in situ through mechanical stabilisation and cell-mediated regeneration. In this study, we designed and 3D-printed millimetre-scale micro-patterned PEGDA biomaterial microscaffolds which self-assemble through tessellation at a scale relevant for applications in osteochondral cartilage reconstruction. Using simulated chondral lesions in an in vitro model, a series of scaffold designs and viscous delivery solutions were assessed. Hexagonal microscaffolds (750 µm x 300 µm) demonstrated the best coverage of a model cartilage lesion (at 73.3%) when injected with a 1% methyl cellulose solution. When chondrocytes were introduced to the biomaterial via a collagen hydrogel, they successfully engrafted with the printed microscaffolds and survived for at least 14 days in vitro, showing the feasibility of reconstructing stratified cartilaginous tissue using this strategy. Our study demonstrates a promising application of this 4D-printed injectable technique for future clinical applications in osteochondral tissue engineering. Supplementary Information: The online version contains supplementary material available at 10.1007/s40964-022-00360-0.

In Situ Single-Cell Bacterial Imaging Provides Mechanistic Insight into the Photodynamic Action of Photosensitizer-Loaded Hydrogels.

Hydrogels, three-dimensional hydrophilic polymeric networks with high water retaining capacity, have gained prominence in wound management and drug delivery due to their tunability, softness, permeability, and biocompatibility. Electron-beam polymerized poly(ethylene glycol) diacrylate (PEGDA) hydrogels are particularly useful for phototherapies such as antimicrobial photodynamic therapy (aPDT) due to their excellent optical properties. This work takes advantage of the transparency of PEGDA hydrogels to investigate bacterial responses to aPDT at the single-cell level, in real-time and in situ. The photosensitizer methylene blue (MB) was loaded in PEGDA hydrogels by using two methods: reversible loading and irreversible immobilization within the 3D polymer network. MB release kinetics and singlet oxygen generation were studied, revealing the distinct behaviors of both hydrogels. Real-time imaging of Escherichia coli was conducted during aPDT in both hydrogel types, using the Min protein system to report changes in bacterial physiology. Min oscillation patterns provided mechanistic insights into bacterial photoinactivation, revealing a dependence on the hydrogel preparation method. This difference was attributed to the mobility of MB within the hydrogel, affecting its direct interaction with bacterial membranes. These findings shed light on the complex interplay between hydrogel properties and the bacterial response during aPDT, offering valuable insights for the development of antibacterial wound dressing materials. The study demonstrates the capability of real-time, single-cell fluorescence microscopy to unravel dynamic bacterial behaviors in the intricate environment of hydrogel surfaces during aPDT.

Fabrication and characterization of coated microneedle patches based on PEGDA for transdermal administration of metformin.

Type 2 diabetes is one of the major challenges that the world is facing today. However, metformin (MET) as most type 2 diabetics' first-line oral hypoglycemic drug may cause serious side effects such as gastrointestinal irritation and nausea which reduce the patients' medication compliance. Therefore, the aim of the study was to design a safe and effective self-treatment device for the delivery of MET. Here, a kind of coated microneedle (MN) patches based on poly(ethylene glycol)diacrylate (PEGDA) were prepared by a two-step casting method and photopolymerization process for transdermal administration of MET. The needles wrapped with drug-loaded hyaluronic acid (HA) coating showed promising mechanical properties and drug delivery ability that allowed them to penetrate the skin barrier for rapid drug delivery, and they had no skin irritancy. The in vivo experiment of type 2 diabetic rats showed a satisfying hypoglycemic effect of the coated MN patches. The study shows that the prepared MN patches will be a potential method for the treatment of type 2 diabetes in the future.

Manipulating mechanical properties of PEG-based hydrogel nanocomposite: A potential versatile bio-adhesive for the suture-less repair of tissue.

Multifunctional bio-adhesives with tunable mechanical properties are obtained by controlling the orientation of anisotropic particles in a blend of fast-curing hydrogel with an imposed capillary flow. The suspensions' microstructural evolution was monitored by the small-angle light scattering (SALS) method during flow up to the critical Péclet number (Pe≈1) necessary for particle orientation and hydrogel crosslinking. The multifunctional bio-adhesives were obtained by combining flow and UV light exposure for rapid photo-curing of PEGDA medium and freezing titania rods' ordered microstructures. Blending the low- and high-molecular weight of PEGDA polymer improved the mechanical properties of the final hydrogel. All the hydrogel samples were non-cytotoxic up to 72 h after cell culturing. The system shows rapid blood hemostasis and promotes adhesive and cohesive strength matching targeted tissue properties with an applicating methodology compatible with surgical conditions. The developed SALS approach to optimize nanoparticles' microstructures in bio-adhesive applies to virtually any optically transparent nanocomposite and any type of anisotropic nanoparticles. As such, this method enables rational design of bio-adhesives with enhanced anisotropic mechanical properties which can be tailored to potentially any type of tissue.

Advancing bovine in vitro fertilization through 3D printing: the effect of the 3D printed materials.

Nowadays there is an increasing demand for assisted reproductive technologies due to the growth of infertility problems. Naturally, fertilization occurs in the oviduct, where the oviductal epithelial cells (OECs) secrete many molecules that affect the embryo's metabolism and protect it from oxidative stress. When the OECs are grown in 3D culture systems, they maintain a great part of their functional characteristics, making them an excellent model for in vitro fertilization (IVF) studies. In this work, we aimed to evaluate the suitability of different 3D-printing processes in conjunction with the corresponding set of commercially available biomaterials: extrusion-based processing using polylactic acid (PLA) and polycaprolactone (PCL) and stereolithography or digital-light processing using polyethylene-glycol-diacrylate (PEGDA) with different stiffness (PEGDA500, PEGDA200, PEGDA PhotoInk). All the 3D-printed scaffolds were used to support IVF process in a bovine embryo assay. Following fertilization, embryo development and quality were assessed in terms of cleavage, blastocyst rate at days 7 and 8, total cell number (TCN), inner cell mass/trophectoderm ratio (ICN/TE), and apoptotic cell ratio (ACR). We found a detrimental effect on cleavage and blastocyst rates when the IVF was performed on any medium conditioned by most of the materials available for digital-light processing (PEGDA200, PEGDA500). The observed negative effect could be possibly due to some leaked compound used to print and stabilize the scaffolds, which was not so evident however with PEGDA PhotoInk. On the other hand, all the extrusion-based processable materials did not cause any detrimental effect on cleavage or blastocyst rates. The principal component analysis reveals that embryos produced in presence of 3D-printed scaffolds produced via extrusion exhibit the highest similarity with the control embryos considering cleavage, blastocyst rates, TCN, ICN/TE and ACR per embryo. Conversely, all the photo-cross linkable materials or medium conditioned by PLA, lead to the highest dissimilarities. Since the use of PCL scaffolds, as well as its conditioned medium, bring to embryos that are more similar to the control group. Our results suggest that extrusion-based 3D printing of PCL could be the best option to be used for new IVF devices, possibly including the support of OECs, to enhance bovine embryo development.

Selective Adsorption of Ionic Species Using Macroporous Monodispersed Polyethylene Glycol Diacrylate/Acrylic Acid Microgels with Tunable Negative Charge.

Monodispersed polyethylene glycol diacrylate (PEGDA)/acrylic acid (AA) microgels with a tuneable negative charge and macroporous internal structure have been produced using a Lego-inspired droplet microfluidic device. The surface charge of microgels was controlled by changing the content of AA in the monomer mixture from zero (for noncharged PEGDA beads) to 4 wt%. The macroporosity of the polymer matrix was introduced by adding 20 wt% of 600-MW polyethylene glycol (PEG) as a porogen material into the monomer mixture. The porogen was successfully leached out with acetone after UV-crosslinking, which resulted in micron-sized cylindrical pores with crater-like morphology, uniformly arranged on the microgel surface. Negatively charged PEGDA/AA beads showed improved adsorption capacity towards positively charged organic dyes (methylene blue and rhodamine B) compared to neutral PEGDA beads and high repulsion of negatively charged dye molecules (methyl orange and congo red). Macroporous microgels showed better adsorption properties than nonporous beads, with a maximum adsorption capacity towards methylene blue of 45 mg/g for macroporous PEGDA/AA microgels at pH 8.6, as compared to 23 mg/g for nonporous PEGDA/AA microgels at the same pH. More than 98% of Cu(II) ions were removed from 50 ppm solution at pH 6.7 using 2.7 mg/mL of macroporous PEGDA/AA microgel. The adsorption of cationic species was significantly improved when pH was increased from 3 to 9 due to a higher degree of ionization of AA monomeric units in the polymer network. The synthesized copolymer beads can be used in drug delivery to achieve improved loading capacity of positively charged therapeutic agents and in tissue engineering, where a negative charge of scaffolds coupled with porous structure can help to achieve improved permeability of high-molecular-weight metabolites and nutrients, and anti-fouling activity against negatively charged species.

Factors That Influence Base-Catalyzed Thiol-Ene Hydrogel Synthesis.

Injectable, localized drug delivery using hydrogels made from ethoxylated trimethylolpropane tri-3-mercaptopropionate (ETTMP) and poly(ethylene glycol) diacrylate (PEGDA) has shown great potential due to these hydrogels' ability to exhibit non-swelling behavior and tunable drug release properties. However, current synthesis methods in the literature suffer from poor ETTMP solubility in water, slow gelation times exceeding 20 min, and a lack of reproducibility. To address these limitations, we have developed a reliable synthesis procedure and conducted a sensitivity analysis of key variables. This has enabled us to synthesize ETTMP-PEGDA hydrogels in a polymer concentration range of 15 to 90 wt% with gelation times of less than 2 min and moduli ranging from 3.5 to 190 kPa. We overcame two synthesis limitations by identifying the impact of residual mercaptopropionic acid and alumina purification column height on gelation time and by premixing ETTMP and PEGDA to overcome low ETTMP solubility in water. Our ETTMP-PEGDA mixture can be stored at -20 °C for up to 2 months without crosslinking, allowing easy storage and shipment. These and previous results demonstrate the potential of ETTMP-PEGDA hydrogels as promising candidates for injectable, localized drug delivery with tunable drug release properties.

High-Fidelity Extrusion Bioprinting of Low-Printability Polymers Using Carbopol as a Rheology Modifier.

Extrusion three-dimensional (3D) bioprinting is a promising technology with many applications in the biomedical and tissue engineering fields. One of the key limitations for the widespread use of this technology is the narrow window of printability that results from the need to have bioinks with rheological properties that allow the extrusion of continuous filaments while maintaining high cell viability within the materials during and after printing. In this work, we use Carbopol (CBP) as rheology modifier for extrusion printing of biomaterials that are typically nonextrudable or present low printability. We show that low concentrations of CBP can introduce the desired rheological properties for a wide range of formulations, allowing the use of polymers with different cross-linking mechanisms and the introduction of additives and cells. To explore the opportunities and limitations of CBP as a rheology modifier, we used ink formulations based on poly(ethylene glycol)diacrylate with extrusion 3D printing to produce soft, yet stable, hydrogels with tunable mechanical properties. Cell-laden constructs made with such inks presented high viability for cells seeded on top of cross-linked materials and cells incorporated within the bioink during printing, showing that the materials are noncytotoxic and the printed structures do not degrade for up to 14 days. To our knowledge, this is the first report of the use of CBP-containing bioinks to 3D-print complex cell-laden structures that are stable for days and present high cell viability. The use of CBP to obtain highly printable inks can accelerate the evolution of extrusion 3D bioprinting by guaranteeing the required rheological properties and expanding the number of materials that can be successfully printed. This will allow researchers to develop and optimize new bioinks focusing on the biochemical, cellular, and mechanical requirements of the targeted applications rather than the rheology needed to achieve good printability.

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.

Carboxymethyl Chitosan Hydrogels for Effective Wound Healing-An Animal Study.

Hydrogels have various applications in medicine, for example, in systems for controlled drug release or as wound dressings, where they provide an appropriate environment for healing and constitute a barrier to microorganisms. The aim of this study was to evaluate the action of carboxymethyl chitosan (CMCS) hydrogels in wound healing therapy in vivo using a laboratory rat model. The hydrogels were formed from aqueous solutions of a CMCS biopolymer via electron beam irradiation, with the presence of a crosslinking agent of poly(ethylene glycol) diacrylate. A histopathological examination of injured tissue, using a model of a hard-to-heal wound, indicated that the CMCS hydrogel supported healing. The new gel dressing, being noncytotoxic, presents great potential in wound treatment, with positive effects on the amount of inflammatory infiltration, young collagen formation, and the degree of epidermalization. A key advantage of the current approach (i.e., using competitive radiation technology for synthesis) is that it includes only one step, with the product being sterilized as it is synthesized. The hydrogel effectively supports wound healing and can serve as a bio-based and biodegradable platform for other medical applications.

In vitro enzymatic degradation of the PTMC/cross-linked PEGDA blends.

Introduction: Poly(1,3-trimethylene carbonate) (PTMC) is a flexible amorphous polymer with good degradability and biocompatibility. The degradation of PTMC is critical for its application as a degradable polymer, more convenient and easy-to-control cross-linking strategies for preparing PTMC are required. Methods: The blends of poly(trimethylene carbonate) (PTMC) and cross-linked poly(ethylene glycol) diacrylate (PEGDA) were prepared by mixing photoactive PEGDA and PTMC and subsequently photopolymerizing the mixture with uv light. The physical properties and in vitro enzymatic degradation of the resultant PTMC/cross-linked PEGDA blends were investigated. Results: The results showed that the gel fraction of PTMC/cross-linked PEGDA blends increased while the swelling degree decreased with the content of PEGDA dosage. The results of in vitro enzymatic degradation confirmed that the degradation of PTMC/cross-linked PEGDA blends in the lipase solution occurred under the surface erosion mechanism, and the introduction of the uv cross-linked PEGDA significantly improved the resistance to lipase erosion of PTMC; the higher the cross-linking degree, the lower the mass loss. Discussion: The results indicated that the blends/cross-linking via PEGDA is a simple and effective strategy to tailor the degradation rate of PTMC.

Generation of Photopolymerized Microparticles Based on PEGDA Hydrogel Using T-Junction Microfluidic Devices: Effect of the Flow Rates.

The formation of microparticles (MPs) of biocompatible and biodegradable hydrogels such as polyethylene glycol diacrylate (PEGDA) utilizing microfluidic devices is an attractive option for entrapment and encapsulation of active principles and microorganisms. Our research group has presented in previous studies a formulation to produce these hydrogels with adequate physical and mechanical characteristics for their use in the formation of MPs. In this work, hydrogel MPs are formed based on PEGDA using a microfluidic device with a T-junction design, and the MPs become hydrogel through a system of photopolymerization. The diameters of the MPs are evaluated as a function of the hydrodynamic condition flow rates of the continuous (Qc) and disperse (Qd) phases, measured by optical microscopy, and characterized through scanning electron microscopy. As a result, the following behavior is found: the diameter is inversely proportional to the increase in flow in the continuous phase (Qc), and it has a significant statistical effect that is greater than that in the flow of the disperse phase (Qd). While the diameter of the MPs is proportional to Qd, it does not have a significant statistical effect on the intervals of flow studied. Additionally, the MPs' polydispersity index (PDI) was measured for each experimental hydrodynamic condition, and all values were smaller than 0.05, indicating high homogeneity in the MPs. The microparticles have the potential to entrap pharmaceuticals and microorganisms, with possible pharmacological and bioremediation applications.