Study of cell migration trajectory on two-dimensional continuous stiffness gradient surface edited by grayscale photopolymerization.

In native tissues, cells encounter a diverse range of stiffness, which can significantly affect their behavior and function. The ability of cells to sense and respond to these mechanical cues is essential for various physiological processes, including cell migration. Cell migration is a complex process influenced by multiple factors, with substrate stiffness emerging as a critical determinant. This study developed a technique to edit the stiffness of polyacrylamide (PAA) hydrogel substrates by adjusting the grayscale level of a photomask during photopolymerization. By analyzing cell morphologies on the hydrogel, we confirmed the development of a single PAA hydrogel substrate with continuous stiffness gradients. This method was used to explore the correlation between substrate stiffness and cell migration dynamics. The study found that cells typically migrated from softer to stiffer surfaces. When the cells initially located on stiffer surfaces, they were able to travel longer distances. Additionally, a continuous 2D stiffness gradient surface was fabricated to explore how cells migrate on smoother versus steeper stiffness gradients. The results showed that cells tended to migrate more readily on smoother stiffness gradient surfaces compared to steeper ones. This study provides valuable insights into cell migration dynamics on substrates with varying stiffness gradients. The results underscore the importance of the mechanical environment in cancer cell migration and offer promising directions for developing interventions to prevent cancer spread.

Copolymerized Polymers Based on Cyclodextrins and Cationic Groups Enhance Therapeutic Effect of Rebamipide in the N-Acetylcysteine-Treated Dry Eye Model.

Purpose: We aimed to prepare a ß-cyclodextrin (ß-CD) polymer using radical polymerization with co-monomers, 6-deoxy-6-(2-methacryloyloxyethylsuccinamide)-ß-cyclodextrin (CD-MSAm) and N,N,N-trimethyl-N-(2-hydroxy-3-metacryloyloxopropyl)-ammonium chloride (QA) to design cyclodextrins suitable for use in ophthalmology. In addition, we evaluated their solubility and inclusion properties with rebamipide (REB), a poorly soluble drug, and investigated the usefulness of the ß-CD polymer and REB (REB@CDQA) combination in treating dry eye. Methods: The ß-CD polymer (CD-MSAm-co-QA, CDQA) based on CD-MSAm/QA was prepared via radical polymerization, and the usefulness of REB@CDQA in treating dry eye was evaluated using a rabbit treated with N-acetylcysteine (dry eye model). Results: The solubility of the CDQA powder was higher than that of the ß-CD powder, and 80 nm colloids were observed in the CDQA solution. No corneal toxicity was observed in human corneal epithelial cells or rat corneas treated with 0.2% CDQA solution. The levels of REB dissolved in the CDQA solution were higher than those of the ß-CD solution. Moreover, the application of the CDQA solution enhanced REB retention in the cornea and attenuated the transcorneal penetration of REB. In addition, instillation of REB@CDQA enhanced the volume of the lacrimal fluid and normalized the reduced mucin levels in the dry eye model. The extent of tear film breakup was attenuated by REB@CDQA instillation. Conclusion: The CDQA solution enhanced the solubility of REB, and the combination of CDQA and REB enhanced the drug content in the corneal tissue. Moreover, the therapeutic effect on dry eye was higher than that of REB suspensions without CDQA.

Development of a Human Recombinant Collagen for Vat Polymerization-Based Bioprinting.

In light-based 3D-bioprinting, gelatin methacrylate (GelMA) is one of the most widely used materials, as it supports cell attachment, and shows good biocompatibility and degradability in vivo. However, as an animal-derived material, it also causes safety concerns when used in medical applications. Gelatin is a partial hydrolysate of collagen, containing high amounts of hydroxyproline. This causes the material to form a thermally induced gel at ambient temperatures, a behavior also observed in GelMA. This temperature-dependent gelation requires precise temperature control during the bioprinting process to prevent the gelation of the material. To avoid safety concerns associated with animal-derived materials and reduce potential issues caused by thermal gelation, a recombinant human alpha-1 collagen I fragment was expressed in Komagataella phaffii without hydroxylation. The resulting protein was successfully modified with methacryloyl groups and underwent rapid photopolymerization upon ultraviolet light exposure. The developed material exhibited slightly slower polymerization and lower storage modulus compared to GelMA, while it showed higher stretchability. However, unlike the latter, the material did not undergo physical gelation at ambient temperatures, but only when cooled down to below 10°C, a characteristic that has not been described for comparable materials so far. This gelation was not caused by the formation of triple-helical structures, as shown by the absence of the characteristic peak at 220 nm in CD spectra. Moreover, the developed recombinant material facilitated cell adherence with high cell viability after crosslinking via light to a 3D structure. Furthermore, desired geometries could be easily printed on a stereolithographic bioprinter.

Bacteria-instructed synthesis of free radical polymers for highly sensitive detection of Escherichia coli and Staphylococcus aureus.

BACKGROUND: Foodborne pathogens such as Escherichia coli and Staphylococcus aureus commonly found in food and water sources are the leading causes of foodborne disease outbreaks, which have become a worldwide issue that can lead to serious health problems and socio-economic losses. Therefore, the development of accurate and timely detection methods for these bacteria is essential to safeguard public health and food safety. However, due to the drawbacks of conventional detection methods such as complex operation, high cost, low specificity and sensitivity, developing efficient and sensitive techniques remains a challenge. RESULTS: In this study, we developed a fluorescent biosensor based on bacteria-instructed atom transfer radical polymerization (ATRP) for ultrasensitive and specific detection of foodborne pathogenic bacteria. This approach first attaches initiators of ATRP to the surface of carboxylated Fe3O4 magnetic beads via transition metal and subsequently utilizes the distinctive copper-binding redox pathway of bacteria to reduce Cu(II) to Cu(I), which activates the surface-initiated polymerization for in situ growth of fluorescent polymer. This signal amplification strategy significantly enhanced the sensitivity of fluorescence analysis performance. Under optimal conditions, there was a perfect linear correlation between the fluorescence signal intensity and the logarithm of the concentrations of S. aureus and E. coli over the range from 103 CFU/mL to 108 CFU/mL, with the detection limits down to 102 CFU/mL for both. SIGNIFICANCE: The fluorescent biosensor provides an efficient, sensitive and stable solution for the direct detection of S. aureus/E. coli, confirming the feasibility of the bacterial-instructed ATRP reaction as a signal amplification strategy. This detection method does not require the help of any external stimuli or complex equipment. Moreover, it shows great potential for application in detecting pathogenic bacteria in complex food samples.

Computational Study on the Inhibition Mechanisms of the Ziegler-Natta Catalyst in the Propylene Polymerization Process: Part 1 Effects of Acetylene and Methylacetylene.

Acetylene and methylacetylene are impurities commonly found in the raw materials used for the production of polymers such as polypropylene and polyethylene. Experimental evidence indicates that both acetylene and methylacetylene can decrease the productivity of the Ziegler-Natta catalyst and alter the properties of the resulting polymer. However, there is still a lack of understanding regarding the mechanisms through which these substances affect this process. Therefore, elucidating these mechanisms is crucial to develop effective solutions to this problem. In this study, the inhibition mechanisms of the Ziegler-Natta catalyst by acetylene and methylacetylene are presented and compared with the incorporation of the first propylene monomer (chain initiation) to elucidate experimental effects. The Density Functional Theory (DFT) method was used, along with the B3LYP-D3 functional and the 6-311++G(d,p) basis set. The recorded adsorption energies were -11.10, -13.99, and -0.31 kcal mol-1, while the activation energies were 1.53, 2.83, and 28.36 kcal mol-1 for acetylene, methylacetylene, and propylene, respectively. The determined rate constants were 4.68 × 1011, 5.29 × 1011, and 2.3 × 10-8 M-1 s-1 for acetylene, methylacetylene, and propylene, respectively. Based on these values, it is concluded that inhibition reactions are more feasible than propylene insertion only if an ethylene molecule has not been previously adsorbed, as such an event reinforces propylene adsorption.

Synthesis, Structure, and Actual Applications of Double Metal Cyanide Catalysts.

Double metal cyanide (DMC) complexes represent a unique family of materials with an open framework structure. The main current application of these complexes in chemical industry is their use as catalysts (DMCCs) of the ring-opening polymerization of propylene oxide (PO), yielding branched polyols, highly demanded in production of polyurethanes and surfactants. The actual problem of chemical fixing carbon dioxide from the atmosphere gave new impetus to the development of DMCCs, which turned out to be effective in oxirane/CO2 copolymerization. In recent years, new types and formulations of DMCCs were created, so that greater understanding of the reaction mechanisms was achieved and new fields of catalytic applications were found. In the present review, we summarized background and actual information about the synthesis, structure, and mechanisms of the action of DMCCs, as well as their application in the development of new materials and fine chemicals.

Curcumin-Based Molecularly Imprinted Polymer Electropolymerized on Single-Use Graphite Electrode for Dipyridamole Analysis.

A new molecularly imprinted polymer (MIP)-based disposable electrochemical sensor for dipyridamole (DIP) determination was obtained. The sensor was rapidly prepared by potentiodynamic electrochemical polymerization on a pencil graphite electrode (PGE) using curcumin (CUR) as a functional monomer and DIP as a template molecule. After the optimization of the conditions (pH, monomer-template ratio, scan rate, number of cyclic voltammetric cycles applied in the electro-polymerization process and extraction time of the template molecule) for MIP formation, DIP voltammetric behavior at the modified electrode (MIP_PGE) was investigated. DIP oxidation took place in a pH-dependent, irreversible mixed diffusion-adsorption controlled process. Differential pulse voltammetry (DPV) and adsorptive stripping differential pulse voltammetry (AdSDPV) were used to quantify DIP from pharmaceutical and tap water samples. Under optimized conditions (Britton-Robinson buffer at pH = 3.29), the obtained linear ranges were 5.00 × 10-8-1.00 × 10-5 mol/L and 5.00 × 10-9-1.00 × 10-7 mol/L DIP for DPV and AdSDPV, respectively. The limits of detection of the methods were 1.47 × 10-8 mol/L for DPV and 3.96 × 10-9 mol/L DIP for AdSDPV.

Vat Photopolymerization 3D Printing of Hydrogels Embedding Metal-Organic Frameworks for Photodynamic Antimicrobial Therapy.

Given the variability in wounds based on the underlying causes, personalized medicine and tailored care for patients with wounds are required to ensure optimal therapeutic outcomes. With the emergence of high-precision and high-efficiency photocuring 3D printing technology, there is the potential for its use in customizing precise shapes that can match complex wound sites, thereby providing better treatment for patients with wound infections. In this work, porphyrinic metal-organic framework (MOF) crystals, serving as the functional filler, were incorporated into gelatin methacrylate (GelMA) as a photocurable composite resin to investigate the capabilities of producing customizable wound dressings through vat photopolymerization 3D printing. The embedded MOF crystals allow for better control of the photopolymerization process due to photon competition with the photoinitiator, enabling the precise printing of complex structures. In addition, these crystals impart photothermal and photodynamic capabilities to the printed object. The antibacterial assay confirms the potent photothermal and photodynamic bactericidal properties of the printed GelMA/MOF hydrogels. The hydrogel with the highest MOF content exhibited over 99.99% antibacterial efficiency against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli after 30 min of light exposure (∼30 mW/cm2, λ ≥ 420 nm). Simultaneously, hemolysis and cytotoxicity evaluations validated their excellent biocompatibility. The findings presented here introduce a strategy for integrating photosensitive MOF and 3D printing to fabricate size-adjustable photothermal/photodynamic monoliths and patches, opening perspectives toward personalized treatment for wound management.

Influence of light-polymerizing units and zirconia on the physical, chemical and biological properties of self-adhesive resin cements.

BACKGROUND: Self-adhesive resin cements (SARCs) are widely used for fixed prostheses, but incomplete cleaning near the gingival margin can cause inflammation. However, the factors influencing cement properties and the biological response of gingival fibroblasts to cement eluates are not well understood. This study examines the impact of two light-polymerizing units (LPUs) on the physical and chemical properties of two SARCs under simulated clinical conditions, as well as the subsequent response of human gingival fibroblasts (hGFs) to these eluates. METHODS: Dental cement discs of SARCs were polymerized using Kerr DemiPlus and 3 M Elipar DeepCure-S LED LPUs with or without a 2-mm thick zirconia screen. Physical properties (microhardness, surface roughness, residual monomers) were evaluated. hGFs' cell viability, wound healing potency, and gene expression were assessed. RESULTS: Both Maxcem and RelyX exhibited reduced microhardness and increased surface roughness when polymerized through zirconia or with DemiPlus LPU. Higher residual monomers (HEMA and GDMA in Maxcem; TEGDMA in RelyX) concentration was observed with DemiPlus and zirconia polymerization. Maxcem polymerized with DemiPlus exhibited lower cell viability, impaired healing, and altered gene expression in hGFs compared to those polymerized with Elipar LPU. Gene expression changes included downregulated NRF2 and HO-1 and upregulated CCR-3. CONCLUSIONS: Light-polymerizing Maxcem through zirconia with DemiPlus LPU compromised SARCs' properties, leading to higher residual monomers and negatively impacting hGFs' viability, healing, and gene expression. Careful material selection and polymerization techniques are crucial to minimize adverse effects on surrounding tissues. CLINICAL SIGNIFICANCE: Clinicians should exercise caution when using LPUs and SARCs, especially when polymerizing through zirconia. This will help optimize the physical and chemical properties of SARCs and minimize potential adverse effects on the surrounding gingival soft tissues.

A novel low shrinkage dimethacrylate monomer as an alternative to BisGMA for adhesive and resin-based composite applications.

The aim of this study was to develop a mixture of dimethacrylate isomers (PG6EMA) as a potential monomer for dental adhesives and composites. PG6EMA was synthesized de novo and characterized in the presence of ethanol (3%, 6% or 9%). BisGMA/TEGDMA (BTEG, 50/50 wt.%) was used as the resin control. Composites were formulated with 60 wt.% of either PG6EMA or BisGMA (40 wt.% TEGDMA and 70 wt.% filler). DMPA (0.2 wt.%) and DPI-PF6 (0.4 wt.%) were added as photoinitiators, irradiated with a mercury arc lamp (320-500 nm, 500 mW/cm2; Acticure). All materials were tested for polymerization kinetics (near-infrared), viscosity (η) and storage modulus (G', oscillatory rheometry). The composites were further characterized for water sorption/solubility, wet/dry flexural strength/modulus and polymerization stress. Data were analyzed with one-way ANOVA/Tukey's test (α = 0.05). The PG6EMA resins showed lower rates of polymerization compared with BTEG (p = 0.001) but high degrees of conversion (p = 0.002). Solvent concentration did not affect RPMAX but the 6% and 9% mixtures showed higher final DC, likely due to reduced viscosity. PG6EMA had much higher viscosity than BTEG (p <0.001) and lower G' (p = 0.003). Composites modified with PG6EMA have slower polymerization rates (p = 0.001) but higher final DC (p = 0.04) than the control. PG6EMA/TEGDMA showed lower dry/wet flexural strength and comparable dry modulus. The PG6EMA/TEGDMA composite showed a 18.4% polymerization stress reduction compared to the BTEG composite. Both base monomers had similar WS/SL and G'. Within its limitations, this study demonstrated that the newly synthesized PG6EMA was a viable alternative to BisGMA in dental composites.

Enhancing craniofacial bone tissue engineering strategy: integrating rapid wet chemically synthesised bioactive glass with photopolymerized resins.

BACKGROUND: Craniofacial bone regeneration represents a dynamic area within tissue engineering and regenerative medicine. Central to this field, is the continual exploration of new methodologies for template fabrication, leveraging established bio ceramic materials, with the objective of restoring bone integrity and facilitating successful implant placements. METHODS: Photopolymerized templates were prepared using three distinct bio ceramic materials, specifically a wet chemically synthesized bioactive glass and two commercially sourced hydroxyapatite variants. These templates underwent comprehensive characterization to assess their physicochemical and mechanical attributes, employing techniques including Fourier transform infrared spectroscopy, scanning electron microscopy, and nano-computed tomography. Evaluation of their biocompatibility was conducted through interaction with primary human osteoblasts (hOB) and subsequent examination using scanning electron microscopy. RESULTS: The results demonstrated that composite showed intramolecular hydrogen bonding interactions with the photopolymer, while computerized tomography unveiled the porous morphology and distribution within the templates. A relatively higher porosity percentage (31.55 ± 8.70%) and compressive strength (1.53 ± 0.11 MPa) was noted for bioactive glass templates. Human osteoblast cultured on bioactive glass showed higher viability compared to other specimens. Scanning micrographs of human osteoblast on templated showed cellular adhesion and the presence of filopodia and lamellipodia. CONCLUSION: In summary these templates have the potential to be used for alveolar bone regeneration in critical size defect. Photopolymerization of bioceramics may be an interesting technique for scaffolds fabrication for bone tissue engineering application but needs more optimization to overcome existing issues like the ideal ratio of the photopolymer to bioceramics.

Thymosin ß4 promotes zebrafish Mauthner axon regeneration by facilitating actin polymerization through binding to G-actin.

BACKGROUND: Thymosin beta 4 (Tß4) is a monomeric actin-binding protein that plays many roles in biological activities. However, some studies on the role of Tß4 in central axon regeneration have yielded contradictory results. Previous research has focused primarily on cultured cells, leading to a deficiency in in vivo experimental evidence. Therefore, we used a single axon injury model of Mauthner cells in zebrafish larvae to investigate the role of Tß4 in central axon regeneration in vivo. RESULTS: Our results demonstrated that knockout of Tß4 impaired axon regeneration, whereas overexpression of Tß4 promoted axon regeneration. Moreover, this promotion is mediated through the interaction between Tß4 and G-actin. Furthermore, our results suggest that the binding of Tß4 to G-actin promotes actin polymerization rather than depolymerization. In the rapid escape behavior test, larvae with damaged axons presented impaired tail muscle control, resulting in a lack of normal tail bending, termed the straight tail phenomenon. The proportion of straight tails was significantly negatively correlated with axon regeneration length, suggesting that it is a new indicator for assessing rapid escape behavior recovery. Finally, the results showed that the overexpression of Tß4 effectively restored the functionality of rapid escape behaviors mediated by Mauthner cells. CONCLUSIONS: Our results provide evidence that Tß4 promotes central axon regeneration in vivo through binding to G-actin and suggest that Tß4 could serve as a potential polypeptide drug for clinical therapy.

De Novo Synthesis of Error-Free Long Oligos.

This protocol describes the synthesis of long oligonucleotides (up to 401-mer), their isolation from complex mixtures using the catching-by-polymerization (CBP) method, and the selection of error-free sequence via cloning followed by Sanger sequencing. Oligo synthesis is achieved under standard automated solid-phase synthesis conditions with only minor yet critical adjustments using readily available reagents. The CBP method involves tagging the full-length sequence with a polymerizable tagging phosphoramidite (PTP), co-polymerizing the sequence into a polymer, washing away failure sequences, and cleaving the full-length sequence from the polymer. Cloning and sequencing guided selection of error-free sequence overcome the problems of substitution, deletion, and addition errors that cannot be addressed using any other methods, including CBP. Long oligos are needed in many areas such as protein engineering and synthetic biology. The methods described here are particularly important for projects requiring long oligos containing long repeats or stable higher-order structures, which are difficult or impossible to produce using any other existing technologies. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Long oligo synthesis Support Protocol 1: Synthesis of polymerizable tagging phosphoramidite (PTP) Support Protocol 2: Synthesis of 5'-O-Bz phosphoramidite Basic Protocol 2: Catching-by-polymerization (CBP) purification Basic Protocol 3: Error-free sequence selection via cloning and sequencing.

[Preparation of fluorescent carbon dots by flow-assisted melt polymerization for tetracycline detection in medical wastewater].

Tetracycline (TC) is one of the most important therapeutic drugs that is widely used in hospitals. However, its harmful effects on human health and various ecosystems cannot be ignored. Owing to its poor metabolic activity and low biodegradability, TC commonly discharges as the parent compound and accumulates readily in sludges and soils by precipitation from wastewater, which can induce the evolution of antibiotic-resistant bacteria; therefore, it has been listed as one of the new pollutants with potential ecotoxicological risk. The control measures and environmental management of TC pollutants in environmental water samples require precise determination of TC pollutant concentrations. Carbon dots (CDs) are an emerging type of fluorescent material with numerous advantages such as easy preparation, low cost, low toxicity, and good biocompatibility. Consequently, they have attracted widespread attention in the field of TC detection. Herein, we synthesized TE-CDs with good blue-fluorescence performance via flow-assisted melt polymerization using tricarboxylic acid and ethylenediamine as raw precursors. The morphology and structure of the prepared TE-CDs were characterized. The transmission electron microscopy (TEM) results showed that the prepared TE-CDs were well dispersed, with an average diameter of (2.43±0.48) nm. The X-ray diffraction (XRD) results showed that the TE-CDs had an amorphous carbon structure. Infrared spectroscopy and X-ray photoelectron spectroscopy (XPS) characterizations showed that the surface of the TE-CDs was rich in hydrophilic groups, such as amino, hydroxyl, and carboxyl groups, which indicated that TE-CDs had good water solubility and were advantageous for detecting TC in medical wastewater. Subsequently, the optical properties of the TE-CDs were investigated. The fluorescence emission spectra of the TE-CDs were recorded at various excitation wavelengths. The emission spectra of the TE-CDs exhibited excitation wavelength dependence and when the excitation wavelength changes from 300 nm to 400 nm, their fluorescence intensity decreased to varying degrees. The TE-CDs exhibited optimal fluorescence intensity at an excitation wavelength of 368 nm, while the emission wavelength was 448 nm. TC could effectively quench the blue fluorescence of the CDs, and by utilizing this property, the detection of TC concentration could be achieved. After the addition of TC, the fluorescence of the system immediately reached an extreme value, and no significant change was observed within 10 min. An incubation time of 20 s was selected to obtain precise results. Additionally, the TE-CDs exhibited stable fluorescence intensity over a wide pH range. The fluorescence stability of the TE-CDs was investigated, and no significant change in fluorescence intensity was observed after standing for 10 d, indicating that the prepared TE-CDs had excellent fluorescence stability. The fluorescence intensity of the TE-CDs decreased to varying degrees within the range of 2-200 mg/L TC until complete quenching occurred. TC mass concentration in the range of 4-20 mg/L showed a good linear relationship (R2=0.9978) with the fluorescence quenching intensity of the TE-CDs. The limit of detection was 0.2 mg/L. A preliminary investigation was undertaken to explore the quenching mechanism of the TE-CDs fluorescence by TC. Upon addition of TC, a significant reduction in the fluorescence lifetime of the TE-CDs was observed. During the quenching process, no new substances were observed by UV absorption spectroscopy. Additionally, no significant changes in the 1H NMR spectra of the TE-CDs were noted before and after the addition of TC, indicating the absence of an interaction between the TE-CDs and TC. Therefore, the quenching mechanism may involve dynamic quenching. The selectivity and anti-interference ability of the developed method were evaluated; in the presence of interfering substances, TC quenched the fluorescence of the TE-CDs, indicating that the TE-CDs had good selectivity and anti-interference performance towards TC. The method was applied to the quantitative detection of TC in medical wastewater, with recoveries of 96.5%-119.8% and relative standard deviations of 0.8%-2.6%. In conclusion, the analytical performance of the proposed method is comparable with that of previously reported detection methods; moreover, the method has the advantages of low operational cost, simple preparation process, time-saving, and good repeatability. Therefore, the TE-CDs can be used as chemical sensors for the detection of TC in medical wastewater and have good practical applications.

Effect of curcumin on physico-mechanical properties of heat polymerized denture base resin.

PURPOSE: Current denture base resins lack adequate strength and antimicrobial properties, necessitating the exploration of alternative solutions. The purpose of this study was to evaluate the effects of curcumin incorporation on the physico-mechanical properties of heat-cured denture base resin, filling a gap in the literature regarding this correlation. METHODS: Heat-cured denture base resin was supplemented with increasing concentrations of curcumin (CR). Groups were designated as CR-0 (0%), CR-0.05 (0.05%), CR-0.10 (0.10%), CR-0.50 (0.50%), and CR-1 (1%), based on the increasing concentrations of curcumin incorporated into the material. Physico-mechanical properties, including flexural strength, surface roughness, fracture toughness, impact strength, and color difference, were evaluated following the testing standards. Statistical analysis involved Kruskal-Wallis ANOVA followed by Dunn's test for multiple comparisons, with significance set at P ≤ 0.05 and Bonferroni's correction applied to p-values. RESULTS: Flexural strength peaked at 153.80 MPa in the CR-0.10 group, while surface roughness was lowest at 0.14 micrometers in the CR-0.50 group. Fracture toughness reached its highest value at 1.80 kJ/m^2 in the CR-0.05 group, and impact strength was greatest at 6.52 Joules in the CR-0.05 group. Additionally, color difference was least pronounced in the CR-0.50 group. Flexural strength, surface roughness, fracture toughness, impact strength, and color difference varied significantly among the control group and different curcumin concentrations (P < 0.05). CONCLUSIONS: Incorporating curcumin into denture base resin alters both optical and mechanical properties. Further research is required to validate the findings and determine the optimal curcumin concentration without compromising the material efficacy.

Sustainable pretreatment method of lignocellulosic depolymerization for enhanced ruminant productivity using laccase protein immobilized agarose beads.

Laccase, the selectively lignin degrader, vital to the initiation of lignocellulosic deconstruction was immobilized onto activated agarose beads to increase its reuse potential. Laccase cross-linked beads (~ 3.42 mm) recorded a specific activity of 23 Umg- 1, retaining about 80.43% enzyme activity after 45 days of storage. The immobilization yield and efficiency were 89% and 97% respectively. The equilibrium data fitted the Freundlich equation (R2 = 0.9987) demonstrating multilayer adsorption and the presence of Cu, Fe, and S in the elemental analysis of immobilized beads established effective binding between activated agarose beads and the laccase protein. Characterization studies of the immobilized laccase-treated crop residues revealed significant differences in the lignin polymer after each treatment cycle. An increase in digestibility of 26.21% and 7.62% was observed in paddy and finger millet-treated straws respectively, over the controls corroborating efficient lignin depolymerization. The propitious performance of laccase beads authenticated in the batch enzymatic reactor to treat crop residues paves headway as a sustainable green technology in the deconstruction of crop residues for use as ruminant feed, augmenting productivity.

Polymerization kinetics of 3D-printed orthodontic aligners under different UV post-curing conditions.

BACKGROUND: The purpose of the study was to measure the degree of conversion (DC) of direct-printed aligners (DPA) that were post-cured under ambient and nitrogen atmosphere at specific time intervals and investigate the kinetics of polymerization reaction of this material. METHODS: A total of 48 aligners were produced in 4 printing series by a 3D printer with TC-85DAC resin (Graphy Inc). From each series of printing, 12 aligners were included. The aligners were divided into two groups according to their post-curing conditions. One group was post-cured under ambient air with the presence of oxygen and the other under a nitrogen atmosphere, both using the same UV post-curing unit recommended by the company. The aligners were post-cured at six different time intervals: 1, 2, 3, 5, 10, and 20 min. Each time interval included 8 aligners, with 2 aligners from each series. The DC of the cured aligners was measured by means of attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) through acquisition of the respective spectra for each UV-curing condition. Statistical analysis was performed to compare the results and differences within each atmosphere post-curing protocol, as well as between the different selected atmosphere conditions. Statistical significance level was set at p-value ≤ 0.05. RESULTS: Pairwise analysis between post-curing protocols showed statistically significant differences only at the first minute of polymerization. Post-curing with nitrogen did not yield statistically significant results across different time intervals. Post-curing in ambient air showed some significant differences on the 1st and 2nd minute of the post-curing process. CONCLUSIONS: Almost complete double bond conversion was observed. Significant differences were observed only during the first minute of polymerization under the nitrogen atmosphere.

Poly(lactide) Upcycling Approach through Transesterification for Stereolithography 3D Printing.

The legislature determines the recycled and waste contents in fabrication processes to ensure more sustainable production. PLA's mechanical recycling and reuse are limited due to the performance decrease caused by thermal or hydrolytic instability. Our concept introduces an upcycling route involving PLA depolymerization using propylene glycol as a reactant, followed by the methacrylation, assuring the liquid systems' curability provided by radical polymerization. PLA-containing curable systems were studied from a rheological and thermomechanical viewpoint. The viscosity levels varied from 33 to 3911 mPa·s at 30 °C, giving a wide capability potential. The best system reached 2240 MPa storage modulus, 164.1 °C glass-transition temperature, and 145.6 °C heat-resistant index, competitive values to commercial systems. The printability was verified for all of the systems. Eventually, our concept led to SLA resin production containing PLA waste content up to 51 wt %.

The Role of Ligand Exchange in Salen Cobalt Complexes in the Alternating Copolymerization of Propylene Oxide and Carbon Dioxide.

A comparative study of the copolymerization of racemic propylene oxide (PO) with CO2 catalyzed by racemic (salcy)CoX (salcy = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexane; X = perfluorobenzoate (OBzF5) or 2,4-dinitrophenoxy (DNP)) in the presence of a [PPN]Cl ([PPN] = bis(triphenylphosphine)iminium) cocatalyst is performed in bulk at 21 °C and a 2.5 MPa pressure of CO2. The increase in the nucleophilicity of an attacking anion results in the increase in the copolymerization rate. Racemic (salcy)CoX provides a high selectivity of the copolymerization, which can be higher than 99%, and the living polymerization mechanism. Poly(propylene carbonate) (PPC) with bimodal molecular weight distribution (MWD) is formed throughout copolymerization. Both modes are living and are characterized by low dispersity, while their contribution to MWD depends on the nature of the attacking anion. The racemic (salcy)CoDNP/[PPN]DNP system is found to be preferable for the production of PPC with a high yield and selectivity.

Influence of 3D printing system, postpolymerization and aging protocols on resin flexural strength and dimensional stability for printing occlusal splints, models and temporary restorations.

OBJECTIVES: Investigate the effect of different postpolymerization protocols, aging, and 3D printing systems on the flexural strength (σ), dimensional stability, and roughness of resins used to fabricate occlusal splints, dental models, and temporary restorations. MATERIAL AND METHODS: 180 bars (25 × 2 x 2 mm-ISO 4049) of each type of resin (T-Temporary/Cosmos Temp, Yller; OS-Occlusal splint/Cosmos Splint, Yller; MO - Models/ Cosmos Model, Yller) were printed and divided into 12 groups (n = 15) according to the factors: "Postpolymerization" (Ctr - Control; UV - Ultraviolet oven and MW - Microwave); "Printer" (SLA- stereolithography (Forms 2/Formslab); LCD- liquid crystal display (FlashForge Foto 6.0/FlashForge)) and "Aging" (TC - 10,000 thermocycling cycles and Without). Each bar was measured with a digital caliper at 11 points before and after postpolymerization to evaluate dimensional stability. The samples were subjected to the σ test (100Kgf;1 mm/min). Data was evaluated using Three- and Two-way ANOVA, and Tukey's test (5%). Weibull analysis, Scanning Electron Microscopic and optical profilometry was performed. RESULTS: LCD printing system and UV oven postpolymerization exhibited the highest σ (P < .05). The groups printed in SLA and post-polymerized in microwave ovens showed the greatest variations in their dimensions, for the occlusal splint resin, the OS-SLA-MW group (-4.29 ± 3.15)A showed a shrinkage of 40.2%. The resins for models (3.31 ± 0.66)A and temporary (-2.06 ± 1.52)A showed a shrinkage of 33% and 20.6%, respectively. CONCLUSIONS: LCD printing with UV light postpolymerization was the most effective method for resins used in occlusal splints, dental models, and temporary restorations. SLA printing with UV postpolymerization showed the most significant dimensional changes, leading to shrinkage in occlusal splint resins, while model resins and temporary restorations expanded. CLINICAL RELEVANCE: Resins for 3D printing should ideally be post-polymerized with UV light and printed using LCD technology, as this approach results in better mechanical properties and less dimensional change compared to microwave oven post-polymerization.