Highly precise strategy of polygalacturonic acid microcarriers functionalized with zwitterions and specific peptides for MSC screening.

Microcarriers for large-scale cell culture have a broader prospect in cell screening compared with the traditional high cost, low efficiency, and cell damaging methods. However, the equal biological affinity to cells has hindered its application. Therefore, based on the antifouling strategy of zwitterionic polymer, we developed a cell-specific microcarrier (CSMC) for shielding non-target cells and capturing mesenchymal stem cells (MSCs), which has characteristics of high biocompatibility, low background noise and high precision. Briefly, [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide and glycidyl methacrylate were grafted onto polygalacturonic acid, respectively. The former built a hydration layer through solvation to provide an excellent antifouling surface, while the latter provided active sites for the click reaction with sulfhydryl-modified cell-specific peptides, resulting in rapid immobilization of peptides. This method is applicable to the vast majority of polysaccharide materials. The accurate capture ratio of MSCs by CSMC in a mixed multicellular environment is >95 % and the proliferation rate of MSCs on microcarriers is satisfactory. In summary, this grafting strategy of bioactive components lays a foundation for the application of polysaccharide materials in the biomedical field, and the specific adhesive microcarriers also open up new ideas for the development of stem cell screening as well.

Synthesis and biological applications of nanocomposite hydrogels based on the methacrylation of hydroxypropyl methylcellulose and lignin loaded with alpha-pinene.

Oral conditions, such as recurrent aphthous stomatitis, are chronic inflammatory disorders that significantly affect the life quality. This study aims to develop a novel buccal mucoadhesive based on methacrylate hydroxypropyl methylcellulose (M-HPMC) and methacrylate lignin (M-SLS) encapsulated with nanostructured lipid carriers (NLCs) for controlled release of alpha-pinene (α-pinene). NLCs with particle sizes of 152 ± 3 nm were prepared by using stearic acid and oleic acid as solid and liquid lipids, respectively. Following the successful synthesis of M-HPMC and M-SLS, various concentrations of α-pinene loaded NLCs (0, 18, 38, and 50 wt%) were encapsulated in M-HPMC/M-SLS hydrogel. It was demonstrated that the physiological and mechanical performances of hydrogels were changed, depending on the NLC content. Remarkably, the incorporation of 18 wt% NLC improved the compressive strength (143 ± 14 kPa) and toughness (17 ± 1 kJ/m3) of M-HPMC/M-SLS hydrogel. This nanocomposite hydrogel considerably decreased dissipated energy from 1.64 kJ/m3 to 0.99 kJ/m3, after a five-cycle compression test. The nanocomposite hydrogel exhibited controlled α-pinene release for up to 96 h which could significantly improve the antioxidant activity of M-HPMC/M-SLS matrix. Moreover, the reinforcing M-HPMC/M-SLS hydrogel with α-pinene-loaded NLCs resulted in increased adhesive strength (113.5 ± 7.5 kPa) to bovine buccal mucosa and cytocompatibility in contact with fibroblasts.

New Generation of Orthodontic Elastomeric Ligature to Prevent Enamel Demineralization In Vivo.

This study aimed to synthesize a novel elastomeric ligature with dimethylaminohexadecyl methacrylate (DMAHDM) grafted, providing a new strategy for improving the issue of enamel demineralization during fixed orthodontics. DMAHDM was incorporated into elastomeric ligatures at different mass fractions using ultraviolet photochemical grafting. The antibacterial properties were evaluated and the optimal DMAHDM amount was determined based on cytotoxicity assays. Moreover, tests were conducted to evaluate the in vivo changes in the mechanical properties of the elastomeric ligatures. To assess the actual in vivo effectiveness in preventing enamel demineralization, a rat demineralization model was established, with analyses focusing on changes in surface microstructure, elemental composition, and nanomechanical properties. Elastomeric ligatures with 2% DMAHDM showed excellent biocompatibility and the best antibacterial properties, reducing lactic acid production by 65.3% and biofilm bacteria by 50.0% within 24 h, without significant mechanical property differences from the control group (p > 0.05). Most importantly, they effectively prevented enamel demineralization in vivo, enhancing elastic modulus by 73.2% and hardness by 204.8%. Elastomeric ligatures incorporating DMAHDM have shown great potential for application in preventing enamel demineralization, providing a new strategy to solve this issue during fixed orthodontics.

New Amphiphilic Terpolymers of N-Vinylpyrrolidone with Acrylic Acid and Triethylene Glycol Dimethacrylate as Promising Drug Delivery: Design, Synthesis and Biological Properties In Vitro.

The terpolymers of N-vinylpyrrolidone (VP) with acrylic acid and triethylene glycol methacrylate were synthesized with more than 90% yield by radical copolymerization in ethanol from monomeric mixtures of different molar composition (98:2:2, 95:5: 2 and 98:2:5) and their monomer composition, absolute molecular masses and hydrodynamic radii in aqueous media were determined. Using the MTT test, these terpolymers were established to be low toxic for non-tumor Vero cells and HeLa tumor cells. Polymer compositions of hydrophobic dye methyl pheophorbide a (MPP) based on studied terpolymers and linear polyvinylpyrrolidone (PVP) were obtained and characterized in water solution. Quantum-chemical modeling of the MPP-copolymer structures was conducted, and the possibility of hydrogen bond formation between terpolymer units and the MPP molecule was shown. Using fluorescence microscopy, the accumulation and distribution of polymer particles in non-tumor (FetMSC) and tumor (HeLa) cells was studied, and an increase in the accumulation of MPP with both types of particles was found.

GelMA loaded with platelet lysate promotes skin regeneration and angiogenesis in pressure ulcers by activating STAT3.

Pressure ulcers (PU) are caused by persistent long-term pressure, which compromises the integrity of the epidermis, dermis, and subcutaneous adipose tissue layer by layer, making it difficult to heal. Platelet products such as platelet lysate (PL) can promote tissue regeneration by secreting numerous growth factors based on clinical studies on skin wound healing. However, the components of PL are difficult to retain in wounds. Gelatin methacrylate (GelMA) is a photopolymerizable hydrogel that has lately emerged as a promising material for tissue engineering and regenerative medicine. The PL liquid was extracted, flow cytometrically detected for CD41a markers, and evenly dispersed in the GelMA hydrogel to produce a surplus growth factor hydrogel system (PL@GM). The microstructure of the hydrogel system was observed under a scanning electron microscope, and its sustained release efficiency and biological safety were tested in vitro. Cell viability and migration of human dermal fibroblasts, and tube formation assays of human umbilical vein endothelial cells were applied to evaluate the ability of PL to promote wound healing and regeneration in vitro. Real-time polymerase chain reaction (PCR) and western blot analyses were performed to elucidate the skin regeneration mechanism of PL. We verified PL's therapeutic effectiveness and histological analysis on the PU model. PL promoted cell viability, migration, wound healing and angiogenesis in vitro. Real-time PCR and western blot indicated PL suppressed inflammation and promoted collagen I synthesis by activating STAT3. PL@GM hydrogel system demonstrated optimal biocompatibility and favorable effects on essential cells for wound healing. PL@GM also significantly stimulated PU healing, skin regeneration, and the formation of subcutaneous collagen and blood vessels. PL@GM could accelerate PU healing by promoting fibroblasts to migrate and secrete collagen and endothelial cells to vascularize. PL@GM promises to be an effective and convenient treatment modality for PU, like chronic wound treatment.

Anti-inflammatory potential of casein enzymatic hydrolysate/gelatin methacryloyl scaffolds for vital pulp therapy.

OBJECTIVES: To synthesize casein enzymatic hydrolysate (CEH)-laden gelatin methacryloyl (GelMA) fibrous scaffolds and evaluate the cytocompatibility and anti-inflammatory effects on dental pulp stem cells (DPSCs). MATERIALS AND METHODS: GelMA fibrous scaffolds with 10%, 20%, and 30% CEH (w/w) and without CEH (control) were obtained via electrospinning. Chemo-morphological, degradation, and mechanical analyses were conducted to evaluate the morphology and composition of the fibers, mass loss, and mechanical properties, respectively. Adhesion/spreading and viability of DPSCs seeded on the scaffolds were also assessed. The anti-inflammatory potential on DPSCs was tested after the chronic challenge of cells with lipopolysaccharides (LPS), followed by treatment with extracts obtained after immersing the scaffolds in α-MEM. The synthesis of the pro-inflammatory cytokines IL-6, IL-1α, and TNF-α was measured by ELISA. Data were analyzed by ANOVA/post-hoc tests (α = 5%). RESULTS: CEH-laden electrospun fibers had a larger diameter than pure GelMA (p ≤ 0.036). GelMA scaffolds laden with 20% and 30% CEH had a greater mass loss. Tensile strength was reduced for the 10% CEH fibers (p = 0.0052), whereas no difference was observed for the 20% and 30% fibers (p ≥ 0.6736) compared to the control. Young's modulus decreased with CEH (p < 0.0001). Elongation at break increased for the 20% and 30% CEH scaffolds (p ≤ 0.0038). Over time, DPSCs viability increased across all groups, indicating cytocompatibility, with CEH-laden scaffolds exhibiting greater cell viability after seven days (p ≤ 0.0166). Also, 10% CEH-GelMA scaffolds decreased the IL-6, IL-1α, and TNF-α synthesis (p ≤ 0.035). CONCLUSION: CEH-laden GelMA scaffolds facilitated both adhesion and proliferation of DPSCs, and 10% CEH provided anti-inflammatory potential after chronic LPS challenge. CLINICAL RELEVANCE: CEH incorporated in GelMA fibrous scaffolds demonstrated the potential to be used as a cytocompatible and anti-inflammatory biomaterial for vital pulp therapy.

High-Quality Three-Dimensionally Cultured Cells Using Interfaces of Diblock Copolymers Containing Different Ratios of Zwitterionic N-Oxides.

To control three-dimensional (3D) cell spheroid formation, it is well-known the surface physicochemical and mechanical properties of cell culture materials are important; however, the formation and function of 3D cells are still unclear. This study demonstrated the precise control of the formation of 3D cells and 3D cell functions using diblock copolymers containing different ratios of a zwitterionic trimethylamine N-oxide group. The diblock copolymers were composed of poly(n-butyl methacrylate) (PBMA) as the hydrophobic unit for surface coating on a cell culture dish and stabilization in water, and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) as the precursor of N-oxide. The zwitterionic N-oxide converted from 0 to 100% using PDMAEMA. The wettability and surface zeta potential varied with different ratios of N-oxide diblock copolymer-coated surfaces, and the amount of protein adsorbed in the cell culture medium decreased monotonically with increasing N-oxide ratio. 3D cell spheroid formations were observed by seeding human umbilical cord mesenchymal stem cells (hUC-MSCs) in diblock copolymer-coated flat-bottom well plates, and the N-oxide ratio was over 40%. The cells proliferated in two-dimensions (2D) and did not form spheroids when the N-oxide ratio was less than 20%. Interestingly, the expression of undifferentiated markers of hUC-MSCs was higher on surfaces that adsorbed proteins to some extent and formed 50-150 µm spheroids in the range of 40-70% of N-oxide ratio. We revealed that a moderately protein-adsorbed surface allows precise control of spheroid formation and undifferentiated 3D cells and has potential applications for high-quality spheroids in regenerative medicine and drug screening.

Porous Gelatin Methacrylate Gel Engineered by Freeze-Ultraviolet Promotes Osteogenesis and Angiogenesis.

Alveolar bone defect reconstruction is a common challenge in stomatology. To address this, a thermosensitive/photosensitive gelatin methacrylate (GelMA) gel was developed based on various air solubilities and light-curing technologies. The gel was synthesized by using a freeze-ultraviolet (FUV) method to form a porous and quickly (within 15 min) solidifying modified network structure. Unlike other gel scaffolds limited by complex preparation procedures and residual products, this FUV-GelMA gel shows favorable manufacturing ability, promising biocompatibility, and adjustable macroporous structures. The results from a rat model suggested that this gel scaffold creates a conducive microenvironment for mandible reconstruction and vascularization. In vitro experiments further confirmed that the FUV-GelMA gel promotes osteogenic differentiation of human bone marrow mesenchymal stem cells and angiogenesis of human umbilical vein endothelial cells. Investigation of the underlying mechanism focused on the p38 mitogen-activated protein kinase (MAPK) pathway. We found that SB203580, a specific inhibitor of p38 MAPK, abolished the therapeutic effects of the FUV-GelMA gel on osteogenesis and angiogenesis, both in vitro and in vivo. These findings introduced a novel approach for scaffold-based tissue regeneration in future clinical applications.

In vitro analysis of a novel dimethylaminododecyl methacrylate modification of dental acrylic soft liner material.

Soft denture liners have limitations like short lifespan and increased microbial buildup. Despite promise as a non-leaching antimicrobial polymer in dentistry, the impact of dimethylaminododecyl methacrylate (DMADDM) on soft liner performance remains unexplored. This study aimed to evaluate the effect of integrating different concentrations of DMADDM to cold cure acrylic resin soft liner, on its antimicrobial activity, cytotoxicity, and physical properties. The same properties were compared to a conventional commercially available denture soft liner. The study employed a control group (conventional soft liner) and three test groups containing 3.3%, 6.6%, and 10% (total mass fraction) DMADDM, respectively. Antimicrobial activity against Candida albicans and Streptococcus mutans was assessed through colony counts and biofilm biomass. Cytotoxicity was evaluated using an oral epithelial cell line. Additionally, wettability and hardness were measured to assess physical properties. Incorporation of DMADDM significantly reduced Candida albicans and Streptococcus mutans counts, and biofilm biomass, compared to the control. Additionally, DMADDM improved the soft liner's wettability and mitigated long-term hardness increase. In conclusion, DMADDM holds promise in enhancing soft liner performance. However, careful selection of its optimum concentration is crucial to ensure both safety and efficacy for future clinical use.

The preventive effect of photocrosslinked Hep/GelMA hydrogel loaded with PRF on MRONJ.

BACKGROUND: Medication-related osteonecrosis of the Jaw (MRONJ) is a rare but severe side effect in patients treated with medications such as Bisphosphonates (BPs). Its pathophysiological mechanism needs to be more precise. Establishing preventive measures and treatment standards is necessary. This study aimed to develop a composite hydrogel scaffold constituted by methacrylated gelatin (GelMA), methacrylated heparin (HepMA) and PRF, and investigate its potential application value in the prevention of MRONJ. METHODS: GelMA, HepMA, and PRF were prepared using specific ratios for hydrogel scaffolds. Through mechanical properties and biocompatibility analysis, the release rate of growth factors and the ability to promote bone differentiation in vitro were evaluated. To explore the healing-enhancing effects of hydrogels in vivo, the composite hydrogel scaffold was implanted to the MRONJ rat model. Micro-computed tomography (Micro-CT) and histological examination were conducted to evaluate the bone morphology and tissue regeneration. RESULTS: The Hep/GelMA-PRF hydrogel improved the degradation rate and swelling rate. It was also used to control the release rate of growth factors effectively. In vitro, the Hep/GelMA-PRF hydrogel was biocompatible and capable of reversing the inhibitory effect of zoledronic acid (ZOL) on the osteogenic differentiation of MC3T3-E1s. In vivo, the micro-CT analysis and histological evaluation demonstrated that the Hep/GelMA-PRF group exhibited the best tissue reconstruction. Moreover, compared to the ZOL group, the expression of osteogenesis proteins, including osteocalcin (OCN), type collagen I (Col I), and bone morphogenetic protein-2 (BMP-2) in the Hep/GelMA-PRF group were all significantly upregulated (P < 0.05). CONCLUSIONS: The Hep/GelMA-PRF hydrogel scaffold could effectively control the release rate of growth factors, induce osteogenic differentiation, reduce inflammation, and keep a stable microenvironment for tissue repair. It has potential application value in the prevention of MRONJ.

The influence of neutral MDP-Na salt on dentin bond performance and remineralization potential of etch-&-rinse adhesive.

OBJECTIVES: To investigate the effect of neutral 10-methacryloyloxydecyl dihydrogen phosphate salt (MDP-Na) on the dentin bond strength and remineralization potential of etch-&-rinse adhesive. METHODS: Two experimental etch-&-rinse adhesives were formulated by incorporating 0 wt% (E0) or 20 wt% (E20) neutral MDP-Na into a basic primer. A commercial adhesive, Adper Single Bond 2 (SB, 3 M ESPE), served as the control. Sixty prepared teeth were randomly allocated into three groups (n = 20) and bonded using either one of the experimental adhesives or SB. Following 24 h of water storage, the bonded specimens were sectioned into resin-dentin sticks, with four resin-dentin sticks obtained from each tooth for microtensile bond strength (MTBS) test. Half of the sticks from each group were immediately subjected to tensile loading using a microtensile tester at a crosshead speed of 1 mm/min, while the other half underwent tensile loading after 6-month incubation in artificial saliva (AS). The degree of conversion (DC) of both the control and experimental adhesives (n = 6 in each group) and the adsorption properties of MDP-Na on the dentin organic matrix (n = 5 in each group) were determined using Fourier-transform infrared spectrometry. Furthermore, the effectiveness of neutral MDP-Na in promoting the mineralization of two-dimensional collagen fibrils and the adhesive-dentin interface was explored using transmission electron microscopy and selected-area electron diffraction. Two- and one-way ANOVA was employed to assess the impact of adhesive type and water storage on dentin bond strength and the DC (α = 0.05). RESULTS: The addition of MDP-Na into the primer increased both the short- and long-term MTBS of the experimental adhesives (p = 0.00). No difference was noted in the DC between the control, E0 and E20 groups (p = 0.366). The MDP-Na remained absorbed on the demineralized dentin even after thorough rinsing. The intra- and extra-fibrillar mineralization of the two-dimensional collagen fibril and dentin bond hybrid layer was confirmed by transmission electron microscopy and selected-area electron diffraction when the primer was added with MDP-Na. CONCLUSIONS: The use of neutral MDP-Na results in high-quality hybrid layer that increase the dentin bond strength of etch-&-rinse adhesive and provides the adhesive with remineralizing capability. This approach may represent a suitable bonding strategy for improving the dentin bond strength and durability of etch-&-rinse adhesive.

Interleukin-4-Loaded Gelatin Methacryloyl Hydrogel Promotes Subcutaneous Chondrogenesis of Engineered Auricular Cartilage in a Rabbit Model.

Tissue engineering technology offers a promising solution for ear reconstruction; however, it faces the challenge of foreign body reaction and neocartilage malformation. This study investigates the impact of interleukin-4 (IL-4), an anti-inflammatory factor, on cartilage regeneration of hydrogel encapsulating autologous auricular chondrocytes in a rabbit subcutaneous environment. Initially, we assessed the influence of IL-4 on chondrocyte proliferation and determined the appropriate concentration using the CCK-8 test in vitro. Subsequently, we loaded IL-4 into gelatin methacryloyl (GelMA) hydrogel containing chondrocytes and measured its release profile through ELISA. The constructs were then implanted autologously into rabbits' subcutis, and after 3, 7, 14, and 28 days, cartilage matrix formation was evaluated by histological examinations, and gene expression levels were detected by qRT-PCR. Results demonstrated that IL-4 promotes chondrocyte proliferation in vitro, and maximum release from constructs occurred during the first week. In the rabbit subcutaneous implantation model, IL-4-loaded constructs (20 ng/mL) maintained a superior chondrocytic phenotype compared to controls with increased expression of anti-inflammatory factors. These findings highlight IL-4 as a potential strategy for promoting chondrogenesis in a subcutaneous environment and improving ear reconstruction.

In Vitro Model Integrating Substrate Stiffness and Flow to Study Endothelial Cell Responses.

We present an innovative in vitro model aimed at investigating the combined effects of tissue rigidity and shear stress on endothelial cell (EC) function, which are crucial for understanding vascular health and the onset of diseases such as atherosclerosis. Traditionally, studies have explored the impacts of shear stress and substrate stiffness on ECs, independently. However, this integrated system combines these factors to provide a more precise simulation of the mechanical environment of the vasculature. The objective is to examine EC mechanotransduction across various tissue stiffness levels and flow conditions using human ECs. We detail the protocol for synthesizing gelatin methacrylate (GelMA) hydrogels with tunable stiffness and seeding them with ECs to achieve confluency. Additionally, we describe the design and assembly of a cost-effective flow chamber, supplemented by computational fluid dynamics simulations, to generate physiological flow conditions characterized by laminar flow and appropriate shear stress levels. The protocol also incorporates fluorescence labeling for confocal microscopy, enabling the assessment of EC responses to both tissue compliance and flow conditions. By subjecting cultured ECs to multiple integrated mechanical stimuli, this model enables comprehensive investigations into how factors such as hypertension and aging may affect EC function and EC-mediated vascular diseases. The insights gained from these investigations will be instrumental in elucidating the mechanisms underlying vascular diseases and in developing effective treatment strategies.

Effect of viscosity of gelatin methacryloyl-based bioinks on bone cells.

The viscosity of gelatin methacryloyl (GelMA)-based bioinks generates shear stresses throughout the printing process that can affect cell integrity, reduce cell viability, cause morphological changes, and alter cell functionality. This study systematically investigated the impact of the viscosity of GelMA-gelatin bioinks on osteoblast-like cells in 2D and 3D culture conditions. Three bioinks with low, medium, and high viscosity prepared by supplementing a 5% GelMA solution with different concentrations of gelatin were evaluated. Cell responses were studied in a 2D environment after printing and incubation in non-cross-linked bioinks that caused the gelatin and GelMA to dissolve and release cells for attachment to tissue culture plates. The increased viscosity of the bioinks significantly affected cell area and aspect ratio. Cells printed using the bioink with medium viscosity exhibited greater metabolic activity and proliferation rate than those printed using the high viscosity bioink and even the unprinted control cells. Additionally, cells printed using the bioink with high viscosity demonstrated notably elevated expression levels of alkaline phosphatase and bone morphogenetic protein-2 genes. In the 3D condition, the printed cell-laden hydrogels were photo-cross-linked prior to incubation. The medium viscosity bioink supported greater cell proliferation compared to the high viscosity bioink. However, there were no significant differences in the expression of osteogenic markers between the medium and high viscosity bioinks. Therefore, the choice between medium and high viscosity bioinks should be based on the desired outcomes and objectives of the bone tissue engineering application. Furthermore, the bioprinting procedure with the medium viscosity bioink was used as an automated technique for efficiently seeding cells onto 3D printed porous titanium scaffolds for bone tissue engineering purposes.

Stability of the Dentin-Bonded Interface Using Self-Etching Adhesive Containing Diacrylamide after Bacterial Challenge.

Purpose/Aim: Acrylamides are hydrolytically stable at pH lower than 2, and were shown to preserve bonded interface integrity with two-step, total etch adhesives. The objective of this study was to leverage those two characteristics in self-etching primers containing the acidic monomer 10-MDP and test the microtensile bond strength before and after incubation with S. mutans incubation. Materials and Methods: Acidic primers (10 wt % 10-methacryloyloxydecyl dihydrogen phosphate─10-MDP; 45 wt % N,N-diethyl-1,3-bis(acrylamido)propane─DEBAAP, or 2-hydroxyethyl methacrylate─HEMA; 45 wt %, glycerol-dimethacrylate─GDMA) and adhesives (DEBAAP or HEMA/10-MDP/UDMA 45/10/45 wt %) were made polymerizable by the addition of 0.2 wt % camphorquinone, 0.8 wt % ethyl-4-dimethylaminobenzoate, 0.4 wt % diphenyliodonium hexafluorophosphate, and 0.1 wt % butylhydroxytoluene. Nonsolvated materials were characterized for flexural strength (FS), modulus (E), toughness, water sorption/solubility (WS/SL), contact angle, and vinyl conversion (DC). Viscosity was evaluated after adding 20 and 40 vol % ethanol to the primer and adhesive, respectively. The experimental materials or Clearfil SE Bond (CC─commercial control) were used to bond a commercial composite (Filtek Supreme) to the flat surface of human dentin. Microtensile bond strength (MTBS) was tested in 1 mm2 sticks for the 5 primer/bond combinations: CC (Clearfil Bond Primer and Bond), HH (HEMA/HEMA), DD (DEBAAP/DEBAAP), HD (HEMA/DEBAAP), and DH (DEBAAP/HEMA). Prior to testing, sticks were stored in water or biofilm-inducing culture medium with S. mutans for 1 week. Confocal images and FTIR-ATR evaluation evaluated the hybrid layer of the adhesives. Results were analyzed using Student's t-test (WS, SL, DC, contact angle, FS, E, toughness), one-way ANOVA/Tukey's test for viscosity, and two-way ANOVA/Tukey's test for MTBS (95%). Results: HEMA-based materials had lower contact angle (p = 0.004), higher WS (p < 0.001), and similar SL values compared to DEBAAP (p = 0.126). FS (p = 0.171) and E (p = 0.065) dry values were similar, but after one week of water storage, FS/E dropped more significantly for HEMA materials. Dry and wet toughness was greater for DEBAAP (p < 0.001), but it also had the greatest drop (46%). Clearfil bonds had the highest viscosity, followed by DEBAAP and HEMA, respectively (p = 0.002). For the primers, HEMA had the lowest viscosity (p = 0.003). As far as MTBS, all groups tested in water were statistically different when compared with HH (p < 0.001). After storage in biofilm, DH had the highest MTBS value, being statistically different from HH (p = 0.002), CC (p = 0.015), and DD (p = 0.027). Conclusions: The addition of a diacrylamide and its association with HEMA in self-etching adhesive systems provided greater bonding stability after bacterial challenge.

Antibacterial properties of photo-crosslinked chitosan/methacrylated hyaluronic acid nanoparticles loaded with bacitracin.

The current treatments for wounds often fail to induce adequate healing, leaving wounds vulnerable to persistent infections and development of drug-resistant microbial biofilms. New natural-derived nanoparticles were studied to impair bacteria colonization and hinder the formation of biofilms in wounds. The nanoparticles were fabricated through polyelectrolyte complexation of chitosan (CS, polycation) and hyaluronic acid (HA, polyanion). UV-induced photo-crosslinking was used to enhance the stability of the nanoparticles. To achieve this, HA was methacrylated (HAMA, degree of modification of 20 %). Photo-crosslinked nanoparticles obtained from HAMA and CS had a diameter of 478 nm and a more homogeneous size distribution than nanoparticles assembled solely through complexation (742 nm). The nanoparticles were loaded with the antimicrobial agent bacitracin (BC), resulting in nanoparticles with a diameter of 332 nm. The encapsulation of BC was highly efficient (97 %). The BC-loaded nanoparticles showed significant antibacterial activity against gram-positive bacteria Staphylococcus aureus, Methicillin-resistant S. aureus and S. epidermidis. Photo-crosslinked HAMA/CS nanoparticles loaded with BC demonstrated inhibition of biofilm formation and a positive effect on the proliferation of mammalian cells (L929). These crosslinked nanoparticles have potential for the long-term treatment of wounds and controlled antibiotic delivery at the location of a lesion.

RAFT Dispersion PISA with Poly(methyl methacrylate) as Stabilizer Block in Alcohol/Water: Unconventional PISA Morphology Transitions.

Reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization-induced self-assembly (PISA) was conducted in the presence of poly(methyl methacrylate) (PMMA) stabilizer in ethanol/water mixture (80/20 by volume). Two different systems were explored by utilizing (i) 2-ethylhexyl methacrylate (EHMA) and (ii) n-butyl methacrylate (BMA). The morphology transitions of these systems were investigated by varying the polymerization conditions, i.e., the presence of the solvophilic comonomer MMA, the solids content, and the target degree of polymerization (DP). As observed in conventional PISA, the presence of solvophilic comonomer, increase in solids content and target DP promoted the formation of high-order morphology. However, unusual morphology transitions were observed whereby the morphology transformed from high-order morphologies to a mixture of spherical nanoparticles, worms, and vesicles and finally to vesicles with increasing target DP. This unusual evolution may be attributed to the limited solubility of PMMA in the ethanol/water solvent mixture, whereby PMMA is soluble at the polymerization temperature but insoluble at lower temperatures.

Surface roughness of different types of resin composites after artificial aging procedures: an in vitro study.

BACKGROUND: The temperature changes, chemical agents, and brushing activity that resin composite restorations are exposed to in the oral environment can cause changes in surface roughness. In this study, the aim was to investigate in vitro the clinical one-year surface roughness changes of different types of composites (flowable or conventional) from the same companies by subjecting them to immersion in solutions, brushing, and thermal cycling procedures to simulate intraoral conditions. METHODS: Four different resin composite brands were included in the study using both their conventional (Charisma Smart, 3M Filtek Ultimate Universal, Omnichroma, Beautifil II) and flowable resin composites (Charisma Flow, 3M Filtek Ultimate Flowable, Omnichroma Flow, Beautifil Flow Plus F00), giving 4 groups with 2 types of resin composite in each. 40 samples were prepared for each group/resin type, for a total of 320 samples. After initial surface roughness measurements by a mechanical profilometer, the samples were divided into 4 subgroups (n = 10) and immersed in solutions (distilled water, tea, coffee, or wine) for 12 days. The samples were then subjected to 10,000 cycles of brushing simulation and 10,000 cycles of thermal aging. Surface roughness measurements were repeated after the procedures. For statistical analysis, the 3-way analysis of variance and the Tukey test were used (p < 0.05). RESULTS: It was concluded that composite groups and types had an effect on surface roughness at time t0 (p < 0.001). At time t1, the highest surface roughness value was obtained in the Beautifil-conventional interaction. When the surface roughness values between time t0 and t1 were compared, an increase was observed in the Beautifil II and Beautifil Flow Plus F00, while a decrease was observed in the other composite groups. CONCLUSION: Composite groups, types, and solutions had an effect on the surface roughness of resin composites. After aging procedures, it was concluded that the Beautifil group could not maintain the surface structure as it exceeded the threshold value of 0.2 µm for bacterial adhesion.

Direct 3D printing of freeform anisotropic bioactive structure based on shear-oriented ink system.

Various anisotropic tissue structures exist in organisms, including muscle tissue, skin tissue, and nerve tissue. Replicating anisotropic tissue structuresin vitrohas posed a significant challenge. Three-dimensional (3D) printing technology is often used to fabricate biomimetic structures due to its advantages in manufacturing principle. However, direct 3D printing of freeform anisotropic bioactive structures has not been reported. To tackle this challenge, we developed a ternary F/G/P ink system that integrates the printability of Pluronic F127 (F), the robust bioactivity and photocrosslinking properties of gelatin methacryloyl (G), and the shear-induced alignment functionality of high-molecular-weight polyethylene glycol (P). And through this strategic ternary system combination, freeform anisotropic tissue structures can be 3D printed directly. Moreover, these anisotropic structures exhibit excellent bioactivity, and promote orientational growth of different cells. This advancement holds promise for the repair and replacement of anisotropic tissues within the human body.

Enhancing neovascularization post-myocardial infarction through injectable hydrogel functionalized with endothelial-derived EVs.

Over the past three decades, cell therapy development has fallen short of expectations, with many cellular sources demonstrating a 'Janus effect' and raising safety concerns. Extracellular vesicles (EVs), supported by advanced technologies, present a promising avenue in regenerative medicine, offering benefits such as immune tolerance and avoidance of negative aspects associated with cell transplants. Our previous research showcased enhanced and organized subcutaneous vascularization using three-dimensional bioprinted patches containing HUVEC-derived EVs in immunodeficient animal models. In this context, stress conditions on the cells of origin further boosted the EVs' neoangiogenic potential. Since neovascularization is the first regenerative target requiring restoration, the present study aims to complement our previous work by employing an injectable gelatin methacrylate (GelMA) hydrogel functionalized with HUVEC-derived EVs in a pathological condition of acute myocardial infarction. This bioactive hydrogel resulted in reduced fibrosis, improved contractility, and promoted angiogenesis, showing promise in countering tissue deterioration and addressing vascular deficits. Moreover, the molecular characterization of EVs through miRNome and proteomic analyses further supports their potential as bio-additives for hydrogel functionalization. This cell-free approach mitigates immune rejection and oncogenic risks, offering innovative therapeutic advantages.