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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 -
Heliyon May 2023Since the COVID-19 outbreak, the use of disposable plastics has rapidly increased along with the amount of plastic waste. During fragmentation, microplastics and other...
Since the COVID-19 outbreak, the use of disposable plastics has rapidly increased along with the amount of plastic waste. During fragmentation, microplastics and other chemical substances contained in plastics are released. These then enter humans through food which could be problematic considering their hazardous potential. Polystyrene (PS), which is widely used in disposable containers, releases large amounts of microplastics (MPs), but no studies have investigated the release mechanisms of PS-MPs and simultaneously exposed contaminants. Therefore, in this study, the effects of pH (3, 5, 7, and 9), temperature (20, 50, 80, and 100 °C), and exposure time (2, 4, 6, and 8 h) on MPs release were systematically examined. A quantitative/qualitative study of MPs and styrene monomers was performed using microscopy-equipped Fourier-transformed infrared spectroscopy and gas chromatography-mass spectrometry. The release of PS-MPs (36 items/container) and simultaneously exposed pollutants (SEP), such as ethylene glycol monooleate (EGM), was highest at pH 9, 100 °C, and 6 h, which was proportional to the test temperature and time. Under the same conditions, 2.58 μg/L of styrene monomer migrated to the liquid food simulants. The fragmentation was proceeded by oxidation/hydrolysis and accelerated by increased temperature and exposure time. The strong positive correlation between PS-MPs and SEPs releases at pH and temperature indicates that PS-MPs and SEPs follow the same release process. However, a strongly negative correlation between PS-MPs and styrene monomers at the exposed time shows that styrene migration does not follow the same release process, but does its partition coefficient.
PubMed: 37305459
DOI: 10.1016/j.heliyon.2023.e15787 -
Polymers Jan 2024Through the graft polymerization of acrylic monomers onto starch, materials with interesting new properties can be synthesized. Fenton's chemistry, Fe/HO, is considered... (Review)
Review
Through the graft polymerization of acrylic monomers onto starch, materials with interesting new properties can be synthesized. Fenton's chemistry, Fe/HO, is considered to be attractive for the initiation of graft polymerization with the monomer acrylic acid since it is cheap and reacts quickly at ambient conditions and should therefore be easy to scale up. However, the selectivity of the grafting versus the homopolymerization reaction poses a challenge with this monomer and this type of initiator. In the present review paper, we investigate why data from the literature on grafting systems with other monomers and initiation systems tend to show higher graft selectivity. A scheme is presented, based on reaction engineering principles, that supports an explanation for these observed differences. It is found that more selective activation of starch is a factor, but perhaps even more important is a low monomer-to-starch ratio at the starting sites of graft reactions. Since water is the most common solvent, monomers that are less water-soluble have an advantage in this respect. Based on the proposed scheme, methods to improve the graft selectivity with Fenton's initiator and acrylic acid are evaluated. Most promising appears to be a method of gradual monomer dosage. With gelatinized cassava starch in a batch reactor, both the grafting percentage (17 => 29%) and graft selectivity (18 => 31%) could be improved. This can be considered a principal breakthrough. Still, more research and development would be needed to refine the method and to implement the idea in a continuous reactor at a larger scale.
PubMed: 38257054
DOI: 10.3390/polym16020255 -
Molecules (Basel, Switzerland) Feb 2022The three-dimensional structure of monomers and homodimers of CYP102A1/WT (wild-type) proteins and their A83F and A83I mutant forms was predicted using the AlphaFold2...
Prediction of Monomeric and Dimeric Structures of CYP102A1 Using AlphaFold2 and AlphaFold Multimer and Assessment of Point Mutation Effect on the Efficiency of Intra- and Interprotein Electron Transfer.
The three-dimensional structure of monomers and homodimers of CYP102A1/WT (wild-type) proteins and their A83F and A83I mutant forms was predicted using the AlphaFold2 (AF2) and AlphaFold Multimer (AFMultimer) programs, which were compared with the rate constants of hydroxylation reactions of these enzyme forms to determine the efficiency of intra- and interprotein electron transport in the CYP102A1 hydroxylase system. The electron transfer rate constants (), which determine the rate of indole hydroxylation by the CYP102A1 system, were calculated based on the distances (R) between donor-acceptor prosthetic groups (PG) FAD→FMN→HEME of these proteins using factor β, which describes an exponential decay from R the speed of electron transport (ET) according to the tunnelling mechanism. It was shown that the structure of monomers in the homodimer, calculated using the AlpfaFold Multimer program, is in good agreement with the experimental structures of globular domains (HEME-, FMN-, and FAD-domains) in CYP102A1/WT obtained by X-ray structural analysis, and the structure of isolated monomers predicted in AF2 does not coincide with the structure of monomers in the homodimer, although a high level of similarity in individual domains remains. The structures of monomers and homodimers of A83F and A83I mutants were also calculated, and their structures were compared with the wild-type protein. Significant differences in the structure of all isolated monomers with respect to the structures of monomers in homodimers were also found for them, and at the same time, insignificant differences were revealed for all homodimers. Comparative analysis for CYP102A1/WT between the calculated intra- and interprotein distances FAD→FMN→HEME and the rate constants of hydroxylation in these proteins showed that the distance between prosthetic groups both in the monomer and in the dimer allows the implementation of electron transfer between PGs, which is consistent with experimental literature data about . For the mutant form of monomer A83I, an increase in the distance between PGs was obtained, which can restrict electron transportation compared to WT; however, for the dimer of this protein, a decrease in the distance between PGs was observed compared to the WT form, which can lead to an increase in the electron transfer rate constant and, accordingly, . For the monomer and homodimer of the A83F mutant, the calculations showed an increase in the distance between the PGs compared to the WT form, which should have led to a decrease in the electron transfer rate, but at the same time, for the homodimer, the approach of the aromatic group F262 with heme can speed up transportation for this form and, accordingly, the rate of hydroxylation.
Topics: Bacterial Proteins; Cytochrome P-450 Enzyme System; Electron Transport; Models, Molecular; NADPH-Ferrihemoprotein Reductase; Point Mutation; Protein Binding; Protein Conformation; Protein Multimerization; Structure-Activity Relationship
PubMed: 35209175
DOI: 10.3390/molecules27041386 -
Nature Communications Jun 2022An inexpensive and reliable method for molecular crystal structure predictions (CSPs) has been developed. The new CSP protocol starts from a two-dimensional graph of...
An inexpensive and reliable method for molecular crystal structure predictions (CSPs) has been developed. The new CSP protocol starts from a two-dimensional graph of crystal's monomer(s) and utilizes no experimental information. Using results of quantum mechanical calculations for molecular dimers, an accurate two-body, rigid-monomer ab initio-based force field (aiFF) for the crystal is developed. Since CSPs with aiFFs are essentially as expensive as with empirical FFs, tens of thousands of plausible polymorphs generated by the crystal packing procedures can be optimized. Here we show the robustness of this protocol which found the experimental crystal within the 20 most stable predicted polymorphs for each of the 15 investigated molecules. The ranking was further refined by performing periodic density-functional theory (DFT) plus dispersion correction (pDFT+D) calculations for these 20 top-ranked polymorphs, resulting in the experimental crystal ranked as number one for all the systems studied (and the second polymorph, if known, ranked in the top few). Alternatively, the polymorphs generated can be used to improve aiFFs, which also leads to rank one predictions. The proposed CSP protocol should result in aiFFs replacing empirical FFs in CSP research.
PubMed: 35654882
DOI: 10.1038/s41467-022-30692-y -
Polymers Apr 2022Improvements in mechanical properties and a shift of focus towards esthetic dentistry led to the application of dental resins in various areas of dentistry. However,... (Review)
Review
Improvements in mechanical properties and a shift of focus towards esthetic dentistry led to the application of dental resins in various areas of dentistry. However, dental resins are not inert in the oral environment and may release monomers and other substances such as Bisphenol-A (BPA) due to incomplete polymerization and intraoral degradation. Current research shows that various monomers present cytotoxic, genotoxic, proinflammatory, and even mutagenic effects. Of these eluting substances, the elution of BPA in the oral environment is of particular interest due to its role as an endocrine disruptor. For this reason, the release of residual monomers and especially BPA from dental resins has been a cause for public concern. The assessment of patient exposure and potential health risks of dental monomers require a reliable experimental and analytical setup. However, the heterogeneous study design applied in current research hinders biocompatibility testing by impeding comparative analysis of different studies and transfer to the clinical situation. Therefore, this review aims to provide information on each step of a robust experimental and analytical in vitro setup that allows the collection of clinically relevant data and future meta-analytical evaluations.
PubMed: 35566958
DOI: 10.3390/polym14091790 -
Journal of Oral Science 2019The evaluation of the effect of bleaching on monomer release from two composite resins was performed by bleaching two nanohybrid composite resins Filtek Z550 and Tetric...
The evaluation of the effect of bleaching on monomer release from two composite resins was performed by bleaching two nanohybrid composite resins Filtek Z550 and Tetric N-Ceram using two bleaching products Whiteness HP Maxx and Vivastyle. In total, 20 samples were made from each composite resin from which four groups were fabricated (two for each bleaching product). The samples were stored in a 75% ethanol solution, and the solutions were renewed after 1, 7, and 28 days. The monomer release was analyzed using high performance liquid chromatography. The data were analyzed using repeated measures analysis of variance and least significant difference multiple comparison test (α = 0.05). Monomers were found to be released from both composite resins. The amounts of monomer released were found to decrease over time (P < 0.05); however, the resins were not affected by bleaching, and the released monomers were well below toxic doses.
Topics: Composite Resins; Materials Testing
PubMed: 31217386
DOI: 10.2334/josnusd.18-0063 -
Molecules (Basel, Switzerland) May 2021Trends in the dynamically developing application of biocatalysis for the synthesis and modification of polymers over the past 5 years are considered, with an emphasis on... (Review)
Review
Trends in the dynamically developing application of biocatalysis for the synthesis and modification of polymers over the past 5 years are considered, with an emphasis on the production of biodegradable, biocompatible and functional polymeric materials oriented to medical applications. The possibilities of using enzymes not only as catalysts for polymerization but also for the preparation of monomers for polymerization or oligomers for block copolymerization are considered. Special attention is paid to the prospects and existing limitations of biocatalytic production of new synthetic biopolymers based on natural compounds and monomers from biomass, which can lead to a huge variety of functional biomaterials. The existing experience and perspectives for the integration of bio- and chemocatalysis in this area are discussed.
Topics: Biocatalysis; Enzymes; Polymerization; Polymers; Protein Engineering; Publications
PubMed: 34067052
DOI: 10.3390/molecules26092750 -
Proceedings of the Japan Academy.... 2022Introduction of functional groups on polyethylene endows it with a higher surface property and thus various catalysts have been developed for the copolymerization of... (Review)
Review
Introduction of functional groups on polyethylene endows it with a higher surface property and thus various catalysts have been developed for the copolymerization of ethylene with polar vinyl monomers. Aside from vinyl monomers, however, other classes of polar monomers have not found application in the copolymerization with ethylene. Here, in this short review article, our latest studies on catalyst development aiming at the use of non-vinyl polar monomers and the properties of the resulting copolymers are summarized.
Topics: Catalysis; Ethylenes; Polymerization; Polymers
PubMed: 35545528
DOI: 10.2183/pjab.98.014