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Heliyon Sep 2022Monomer ratios play a crucial role on the performances of dental resins, the optimal monomer ratios for dental resins are determined by combining the degree of...
Monomer ratios play a crucial role on the performances of dental resins, the optimal monomer ratios for dental resins are determined by combining the degree of conversion (DC), rate of polymerization (Rp), and mechanical properties, based on commonly-used Bis-GMA (bisphenol A-glycidyl methacrylate), UDMA (urethane dimethacrylate), and TEGDMA (triethyleneglycol dimethacrylate) resins. The DC and mechanical properties of the dental resins are examined by NIR (Near Infrared Ray) spectroscopy and nanoindentation tests, respectively. The results indicate that the Rp increases while the DC decreases with the loading content of Bis-GMA or UDMA in dental resins (i.e., Bis-GMA/TEGDMA and UDMA/TEGDMA). Meanwhile, both elastic modulus and hardness also present a tendency to increase. Various different monomers maybe create a strong polymer matrix in proper proportions, comprehensively comparing the performances of dental resins in different monomer ratios, the cured resins containing Bis-GMA (15-35 wt%), UDMA (37-60 wt%) and TEGDMA (20-35 wt%) show better material properties. The present study offers a quantitative analysis for Bis-GMA/UDMA/TEGDMA dental resins as well as provides guidance for the research of dental resins.
PubMed: 36119854
DOI: 10.1016/j.heliyon.2022.e10554 -
The Angle Orthodontist Sep 2023To quantify the amount of residual monomer released from orthodontic adhesives used in the indirect bonding technique and compare it to a direct bonding composite resin.
OBJECTIVES
To quantify the amount of residual monomer released from orthodontic adhesives used in the indirect bonding technique and compare it to a direct bonding composite resin.
MATERIALS AND METHODS
Five hundred stainless steel orthodontic brackets were bonded on bovine incisors using five groups of bonding resins: Transbond XT (TXT), Transbond Supreme LV (SLV), Sondhi Rapid-Set (SRS), Transbond IDB (IDB), and Custom I.Q. (CIQ). Liquid samples were gathered on the first, seventh, 21st, and 35th days. Residual monomer release was measured from the liquid samples with a liquid chromatography device. In addition, the amount and shape of the adhesive between the tooth surface and the bracket base was evaluated using obtained electron microscopy images. The data were analyzed using analysis of variance, and a Tukey post-hoc test was applied.
RESULTS
Hydroxyethylmethacrylate and bisphenol A-glycidyl methacrylate monomers were released by all study groups. Urethane-dimethacrylate was released from the TXT, SLV, IDB, and CIQ groups. Triethylene glycol dimethacrylate was released from TXT, SLV, IDB, and SRS groups. The amount of total monomer release was higher in chemically cured adhesives than in light-cured adhesives. Among the chemically cured adhesives, premix adhesives had the highest amount of total monomer release. The light-cured adhesives had less thickness.
CONCLUSIONS
Light-curing adhesives have significantly less monomer release than chemically polymerized adhesives.
Topics: Animals; Cattle; Dental Cements; Dental Bonding; Bisphenol A-Glycidyl Methacrylate; Composite Resins; Resin Cements; Orthodontic Brackets; Adhesives; Materials Testing
PubMed: 37212680
DOI: 10.2319/122322-864.1 -
Polymers Nov 2023Isosorbide can be used as a third monomer in the synthesis of aliphatic polyesters, and its V-shaped bridging ring structure can effectively improve the rigidity of the...
Isosorbide can be used as a third monomer in the synthesis of aliphatic polyesters, and its V-shaped bridging ring structure can effectively improve the rigidity of the copolyester molecular chain. In this work, a series of degradable polyester materials were prepared by modifying polybutylene succinate and using isosorbide as the third monomer. The degradation tests in this paper were implemented through the hydrolysis of copolyesters in distilled water, degradation in natural water and degradation tests in simulated natural environments. The results showed that PBS and its copolyesters can degrade under natural conditions, and the introduction of isosorbide can accelerate the degradation of copolyesters, which could effectively reduce pollutants in nature.
PubMed: 38006096
DOI: 10.3390/polym15224372 -
Polymers Nov 2023The introduction of polar functional groups into polyolefin chain structures creates opportunities to enhance specific properties, such as adhesion, dyeability,... (Review)
Review
The introduction of polar functional groups into polyolefin chain structures creates opportunities to enhance specific properties, such as adhesion, dyeability, printability, compatibility, thermal stability, and electrical conductivity, which widen the range of potential applications for these modified materials. Transition metal catalysts, especially late transition metals, have proven to be highly effective in copolymerization processes due to their reduced Lewis acidity and electrophilicity. However, when compared to the significant progress and summary of synthetic methods, there is a distinct lack of a comprehensive summary of mechanistic studies pertaining to the catalytic systems involved in ethylene copolymerization catalyzed by palladium and nickel catalysts. In this review, we have provided a comprehensive summary of the latest developments in mechanistic studies of ethylene copolymerization with polar monomers catalyzed by late-transition-metal complexes. Experimental and computational methods were employed to conduct a detailed investigation of these organic and organometallic systems. It is mainly focused on ligand substitution, changes in binding modes, ethylene/polar monomer insertion, chelate opening, and β-H elimination. Factors that control the catalytic activity, molecular weight, comonomer incorporation ratios, and branch content are analyzed, these include steric repulsions between ligands and monomers, electronic effects arising from both ligands and monomers, and so on.
PubMed: 38006069
DOI: 10.3390/polym15224343 -
Mobile DNA Apr 2022The internal promoter in L1 5'UTR is critical for autonomous L1 transcription and initiating retrotransposition. Unlike the human genome, which features one...
BACKGROUND
The internal promoter in L1 5'UTR is critical for autonomous L1 transcription and initiating retrotransposition. Unlike the human genome, which features one contemporarily active subfamily, four subfamilies (A_I, Gf_I and Tf_I/II) have been amplifying in the mouse genome in the last one million years. Moreover, mouse L1 5'UTRs are organized into tandem repeats called monomers, which are separated from ORF1 by a tether domain. In this study, we aim to compare promoter activities across young mouse L1 subfamilies and investigate the contribution of individual monomers and the tether sequence.
RESULTS
We observed an inverse relationship between subfamily age and the average number of monomers among evolutionarily young mouse L1 subfamilies. The youngest subgroup (A_I and Tf_I/II) on average carry 3-4 monomers in the 5'UTR. Using a single-vector dual-luciferase reporter assay, we compared promoter activities across six L1 subfamilies (A_I/II, Gf_I and Tf_I/II/III) and established their antisense promoter activities in a mouse embryonic fibroblast cell line and a mouse embryonal carcinoma cell line. Using consensus promoter sequences for three subfamilies (A_I, Gf_I and Tf_I), we dissected the differential roles of individual monomers and the tether domain in L1 promoter activity. We validated that, across multiple subfamilies, the second monomer consistently enhances the overall promoter activity. For individual promoter components, monomer 2 is consistently more active than the corresponding monomer 1 and/or the tether for each subfamily. Importantly, we revealed intricate interactions between monomer 2, monomer 1 and tether domains in a subfamily-specific manner. Furthermore, using three-monomer 5'UTRs, we established a complex nonlinear relationship between the length of the outmost monomer and the overall promoter activity.
CONCLUSIONS
The laboratory mouse is an important mammalian model system for human diseases as well as L1 biology. Our study extends previous findings and represents an important step toward a better understanding of the molecular mechanism controlling mouse L1 transcription as well as L1's impact on development and disease.
PubMed: 35443687
DOI: 10.1186/s13100-022-00269-z -
Biochimica Et Biophysica Acta.... Aug 2023Cytochrome bc is a structural and functional homodimer. The catalytically-relevant inter-monomer electron transfer has been implicated by a number of experiments,...
Cytochrome bc is a structural and functional homodimer. The catalytically-relevant inter-monomer electron transfer has been implicated by a number of experiments, including those based on analyses of the cross-dimer mutated derivatives. As some of the original data on these derivatives have recently been questioned, we extend kinetic analysis of these mutants to confirm the enzymatic origin of the observed activities and their relevance in exploration of conditions that expose electron transfer between the monomers. While obtained data consistently implicate rapid inter-monomer electron equilibration in cytochrome bc, the mechanistic and physiological meaning of this equilibration is yet to be established.
Topics: Kinetics; Electrons; Electron Transport; Cytochromes
PubMed: 37164301
DOI: 10.1016/j.bbabio.2023.148981 -
Frontiers in Neurology 2023This research employed a network meta-analysis (NMA) to examine the effectiveness of five traditional Chinese medicine (TCM) monomers for promoting motor function... (Review)
Review
Comparative efficacy of five most common traditional Chinese medicine monomers for promoting recovery of motor function in rats with blunt spinal cord injury: a network meta-analysis.
OBJECTIVE
This research employed a network meta-analysis (NMA) to examine the effectiveness of five traditional Chinese medicine (TCM) monomers for promoting motor function recovery in rats with blunt spinal cord injury (SCI).
METHODS
Wangfang, China National Knowledge Infrastructure, Web of Science, Embase, Chinese Scientific Journal Database, PubMed, and the Chinese Biomedical Literature Databases were searched for retrieving relevant articles published from their inception to December 2022. Two reviewers performed screening of search results, data extraction, and literature quality assessment independently.
RESULTS
For this meta-analysis, 59 publications were included. Based on the recovery of motor function at weeks 1, 2, 3, and 4 in NMA, almost all TCM groups had significantly increased positive effects than the negative control animals. In terms of cumulative probability, the tanshinone IIA (TIIA) group ranked first in restoring motor function in the first week after blunt SCI, and the resveratrol (RSV) group ranked first during the last 3 weeks.
CONCLUSION
The NMA revealed that TCM monomers could effectively restore motor function in the rat model of blunt SCI. In rats with blunt SCI, TIIA may be the most effective TCM monomer during the first week, whereas RSV may be the most effective TCM monomer during the last 3 weeks in promoting motor function recovery. For better evidence reliability in preclinical investigations and safer extrapolation of those findings into clinical settings, further research standardizing the implementation and reporting of animal experiments is required.
SYSTEMATIC REVIEW REGISTRATION
https://inplasy.com/, identifier INPLASY202310070.
PubMed: 37465765
DOI: 10.3389/fneur.2023.1165076 -
Heliyon Aug 2022The present study aims to synthesize and characterize two quaternary ammonium (QAM) based monomers such as - dimethyl-hexadecyl-methacryloxyethyl-ammonium iodide (DHMAI)...
The present study aims to synthesize and characterize two quaternary ammonium (QAM) based monomers such as - dimethyl-hexadecyl-methacryloxyethyl-ammonium iodide (DHMAI) and 2-dimethyl-2-dodecyl-1-methacryloxyethyl ammonium iodine (DDMAI) and assess their cytotoxicity and antimicrobial properties. The study also aims to incorporate the optimized concentration of these monomers as copolymerizing monomers into conventional Polymethyl methacrylate (PMMA) denture base resin and evaluate their suitability for prosthetic applications. DHMAI and DDMAI monomers were synthesized through a Menschutkin reaction and their chemical structure was characterized using FT-IR and H-NMR spectroscopy. Cytotoxicity was determined using Methyl Thiazolyl Tetrazolium (MTT) assay whereas antimicrobial activity was assessed using the agar-disc diffusion method. Subsequently, optimized concentrations of DHMAI or DDMAI, based on the cytotoxicity results, were added to conventional PMMA resin. Antimicrobial activity, cytotoxicity, surface hardness, and water sorption of PMMA denture base rein incorporated with DHMAI or DDMAI were evaluated. FT-IR and H-NMR results confirmed the structure of monomers and copolymerization of DHMAI and DDMAI with PMMA resin. DHMAI and DDMAI monomers were found to be cytocompatible with mouse fibroblast cells up to a concentration of 5 μg/mL and 20 μg/mL respectively. In addition, incorporation of DHMAI or DDMAI at 5 μg/mL and 20 μg/mL respectively into PMMA denture base material did not affect their cytocompatibility. PMMA denture base resin incorporated with DHMAI or DDMAI significantly reduced the adhesion of microbes. Further, an increase in the surface hardness and a reduction in the water sorption was observed. Hence DHMAI and DDMAI can be considered as potential candidates for imparting antimicrobial activity to polymeric denture base materials.
PubMed: 36090206
DOI: 10.1016/j.heliyon.2022.e10374 -
Journal of Functional Biomaterials Aug 2020An advancement in preventing secondary caries has been the incorporation of quaternary ammonium containing (QAC) compounds into a composite resin mixture. The permanent... (Review)
Review
An advancement in preventing secondary caries has been the incorporation of quaternary ammonium containing (QAC) compounds into a composite resin mixture. The permanent positive charge on the monomers allows for electrostatic-based killing of bacteria. Spontaneous adsorption of salivary proteins onto restorations dampens the antimicrobial capabilities of QAC compounds. Protein-repellent monomers can work with QAC restorations to achieve the technology's full potential. We discuss the theory behind macromolecular adsorption, direct and indirect characterization methods, and advances of protein repellent dental materials. The translation of protein adsorption to microbial colonization is covered, and the concerns and fallbacks of the state-of-the-art protein-resistant monomers are addressed. Last, we present new and exciting avenues for protein repellent monomer design that have yet to be explored in dental materials.
PubMed: 32752169
DOI: 10.3390/jfb11030054 -
Nanoscale Aug 2022Directional assembly of nanoscale objects results in morphologies that can broadly be classified as supra-molecular nanopolymers. Such morphologies, given a functional...
Directional assembly of nanoscale objects results in morphologies that can broadly be classified as supra-molecular nanopolymers. Such morphologies, given a functional choice of the monomers used as building blocks, can be of ubiquitous utility in optical, magnetic, rheological, and medical applications. These applications, however, require a profound understanding of the interplay between monomer shape and bonding on one side, and polymeric properties - on the other. Recently, we fabricated nanopolymers using cuboid DNA nanochambers, as they not only allow fine-tuning of the resulting morphologies but can also carry magnetic nanoparticles. However, it is not known if the cuboid shape and inter-cuboid connectivity restrict the equilibrium confirmations of the resulting nanopolymers, making them less responsive to external stimuli. In this work, using Molecular Dynamics simulations, we perform an extensive comparison between various nanopolymer architectures to explore their polymeric properties, and their response to an applied magnetic field if magnetic nanoparticles are embedded. We explain the impact of monomer shape and bonding on the mechanical and magnetic properties and show that DNA nanochambers can build highly responsive and magnetically controllable nanopolymers.
PubMed: 35771156
DOI: 10.1039/d2nr01502a