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Nature Communications Sep 2019Light-induced alteration of macromolecular information plays a central role in biology and is known to influence health, aging and Darwinian evolution. Here, we report...
Light-induced alteration of macromolecular information plays a central role in biology and is known to influence health, aging and Darwinian evolution. Here, we report that light can also trigger sequence variations in abiotic information-containing polymers. Sequence-coded poly(phosphodiester)s were synthesized using four phosphoramidite monomers containing either photo-sensitive or photo-inert substituents. These monomers allow different sequence manipulations. For instance, using two light-cleavable monomers containing o-nitrobenzyl ether and o-nitroveratryl ether motifs, photo-erasable digital polymers were prepared. These polymers can be decoded by tandem mass spectrometry but become unreadable after UVA exposure. The opposite behavior, i.e. photo-revealable sequences, was obtained with polymers made of two isobaric monomers containing light-cleavable o-nitrobenzyl ether and light-inert p-nitrobenzyl ether substituents. Furthermore, when the latter two monomers were used in conjunction with a third monomer bearing a light-inert OH group, site-directed photo-mutations were induced in synthetic polymers. This was used herein to change the meaning of binary sequences.
Topics: Chemistry Techniques, Synthetic; Molecular Structure; Polymers; Tandem Mass Spectrometry; Ultraviolet Rays
PubMed: 31484927
DOI: 10.1038/s41467-019-11566-2 -
Polymers Nov 2018Polyhydroxyalkanoates (PHAs) are polyesters synthesized by bacteria as a carbon and energy storage material. PHAs are characterized by thermoplasticity,... (Review)
Review
Polyhydroxyalkanoates (PHAs) are polyesters synthesized by bacteria as a carbon and energy storage material. PHAs are characterized by thermoplasticity, biodegradability, and biocompatibility, and thus have attracted considerable attention for use in medical, agricultural, and marine applications. The properties of PHAs depend on the monomer composition and many types of PHA monomers have been reported. This review focuses on biosynthesized PHAs bearing aromatic groups as side chains. Aromatic PHAs show characteristics different from those of aliphatic PHAs. This review summarizes the types of aromatic PHAs and their characteristics, including their thermal and mechanical properties and degradation behavior. Furthermore, the effect of the introduction of an aromatic monomer on the glass transition temperature () of PHAs is discussed. The introduction of aromatic monomers into PHA chains is a promising method for improving the properties of PHAs, as the characteristics of aromatic PHAs differ from those of aliphatic PHAs.
PubMed: 30961192
DOI: 10.3390/polym10111267 -
Biomaterial Investigations in Dentistry 2023Biological evaluation of resin-based dental composites has traditionally been based on in vitro endpoint tests with different methods to determine loss of cell... (Review)
Review
Biological evaluation of resin-based dental composites has traditionally been based on in vitro endpoint tests with different methods to determine loss of cell viability and cell morphology changes after exposure to the material or monomer constituents. The data reveals a potential for biological effects, but clinical relevance of such data is limited. Positive allergy tests and allergic clinical reactions to dental monomers are observed in dental personnel and patients. The aim of this review is to address newer research on molecular events caused by exposure to resin-based composites to have a better understanding of the potential for clinical adverse effects. A more accurate understanding of the biological aspects of dental composite materials has been found after studying parameters like glutathione depletion, oxidative stress, genotoxicity, and immunomodulatory key effects in various cell culture models. Using omics-based approaches allow for a broader and non-specified search of changes caused by methacrylate exposure. Defense mechanisms and adaption are observed in cells exposed to monomer concentrations relevant to clinical exposure. The above-mentioned methods are the foundations for modified testing strategies. The clinical relevance of most available in vitro endpoint tests is of limited relevance for the patient. Research focusing on molecular mechanisms has given new insight into methacrylate toxicity in exposed cells. Using this knowledge from mechanistic studies to develop standardized in vitro biocompatibility tests will likely improve their clinical relevance.
PubMed: 37347059
DOI: 10.1080/26415275.2023.2223223 -
Cell Chemical Biology Jul 2022A critical step in repurposing the cellular translation machinery for the synthesis of polymeric products is the acylation of transfer RNA (tRNA) with unnatural... (Review)
Review
A critical step in repurposing the cellular translation machinery for the synthesis of polymeric products is the acylation of transfer RNA (tRNA) with unnatural monomers. Toward this goal, flexizymes, ribozymes capable of aminoacylation, have emerged as a uniquely adept tool for charging tRNA with ever increasingly diverse substrates. In this review, we present a library of monomer substrates that have been tested for tRNA acylation with the flexizyme system. From this mile-high view, we provide insights for understanding the chemical factors that influence flexizyme-mediated tRNA acylation. We conclude that flexizymes are primitive esterification catalysts that display a modest binding affinity to the monomer's aromatic recognition element. Together, these robust, yet flexible, flexizyme systems provide researchers with unprecedented access for preparing unnatural acyl-tRNA and the opportunity to repurpose the translation machinery for the synthesis of novel biologically derived structures beyond native proteins and peptides.
Topics: Acylation; Catalysis; Peptides; RNA, Catalytic; RNA, Transfer; Transfer RNA Aminoacylation
PubMed: 35413283
DOI: 10.1016/j.chembiol.2022.03.012 -
Accounts of Chemical Research Jun 2022Poor waste management and unchecked consumption underpin our current paradigm of plastics use, which is demonstrably unsustainable in the long term. Nonetheless, the...
Poor waste management and unchecked consumption underpin our current paradigm of plastics use, which is demonstrably unsustainable in the long term. Nonetheless, the utility and versatility of plastics suggest that the notion of a plastic-free society is also unsustainable. Responses to this conundrum are increasing, and among these are research efforts focused on the development of more sustainable plastics. This Account, written by trained chemists, reflects an academic research journey culminating in an appreciation of the importance of improving and enabling the overarching systems that plastics exist within. Our primary initial focus was on catalyst development because catalysts are key drivers of sustainability by improving the efficiency and ease of polymerization. Metal catalysts ranging in ligand structure and the incorporated metal(s) were developed for the preparation of traditional polyesters such as poly(lactic acid) and polycaprolactone. The central themes in these works were stereocontrol (tacticity), efficiency (polymerization rate), and versatility (monomer scope). Alongside insights gained by systematically varying catalyst structure came impressive results gained through collaboration, including the remarkably high activity of novel heterometallic zinc catalysts toward various cyclic esters.This catalysis work was complemented by and slowly transitioned to a focus on polymer functionality and monomer design. Several fundamental studies focus on polymer topology, specifically star-shaped polyesters, tuned arm number, length, and tacticity. These reports feature emphases on the end of life (solvolysis) and physical properties of polymers, which were increasingly important themes as work shifted toward new methods of incorporating functionality in polymers produced by ring-opening polymerization. Three key highlights demonstrate this shift: the first two rely upon the exploitation of olefin metathesis (cross- and ring-closing) to functionalize polyesters or polyethers, and the third involves the manipulation of ring-opening polymerization equilibrium to enable selective monomer recovery from a polyester. Our foundational work on 1,3-dioxolan-4-one (DOX) monomers is then discussed because this emerging class of molecules offers a distinct synthetic pathway toward functional polyesters, both conventional and novel. With this DOX framework, polyesters that are usually challenging to synthesize (e.g., poly(mandelic acid)) are accessible because polymerization is driven by the concomitant, controlled extrusion of small molecules (acetone or formaldehyde).After these polyester-focused highlights, the foundation of our ongoing work is presented, namely, that polymer sustainability must be viewed from a systems-level perspective, including economic and social components alongside the environmental considerations. Material design must be driven by practice, and we have to involve key players in academia, industry, and government in a concerted effort to enable positive and robust change. The key goal is to develop sustainable systems that retain plastics in their highest value state for as long as possible by designing materials and products for a particular (and assured) end-of-life fate, whether that be reuse, recycling, (bio)degradation, or energy recovery.
Topics: Metals; Plastics; Polyesters; Polymerization; Polymers
PubMed: 35579567
DOI: 10.1021/acs.accounts.2c00134 -
Genome Research Jun 2022Recent advances in long-read sequencing opened a possibility to address the long-standing questions about the architecture and evolution of human centromeres. They also...
Recent advances in long-read sequencing opened a possibility to address the long-standing questions about the architecture and evolution of human centromeres. They also emphasized the need for centromere annotation (partitioning human centromeres into monomers and higher-order repeats [HORs]). Although there was a half-century-long series of semi-manual studies of centromere architecture, a rigorous centromere annotation algorithm is still lacking. Moreover, an automated centromere annotation is a prerequisite for studies of genetic diseases associated with centromeres and evolutionary studies of centromeres across multiple species. Although the monomer decomposition (transforming a centromere into a monocentromere written in the monomer alphabet) and the HOR decomposition (representing a monocentromere in the alphabet of HORs) are currently viewed as two separate problems, we show that they should be integrated into a single framework in such a way that HOR (monomer) inference affects monomer (HOR) inference. We thus developed the HORmon algorithm that integrates the monomer/HOR inference and automatically generates the human monomers/HORs that are largely consistent with the previous semi-manual inference.
Topics: Algorithms; Centromere; Humans
PubMed: 35545449
DOI: 10.1101/gr.276362.121 -
Angewandte Chemie (International Ed. in... Jan 2023Radical polymerization (RP) of multivinyl monomers (MVMs) provides a facile solution for manipulating polymer topology and has received increasing attention due to their... (Review)
Review
Radical polymerization (RP) of multivinyl monomers (MVMs) provides a facile solution for manipulating polymer topology and has received increasing attention due to their industrial and academic significance. Continuous efforts have been made to understand their mechanism, which is the key to regulating materials structure. Modelling techniques have become a powerful tool that can provide detailed information on polymerization kinetics which is inaccessible by experiments. Many publications have reported the combination of experiments and modelling for free radical polymerization (FRP) and reversible-deactivation radical polymerizations (RDRP) of MVMs. Herein, a minireview is presented for the most important modelling techniques and their applications in FRP/RDRP of MVMs. This review hopes to illustrate that the combination of modelling and wet experiments can be a great asset to polymer researchers and inspire new thinking for the future MVMs experiment optimization and product design.
PubMed: 36413108
DOI: 10.1002/anie.202212235 -
Journal of Pharmacy & Bioallied Sciences May 2019Methyl methacrylate monomer of denture base resins was modified with several monomers to achieve better physico-mechanical properties without compromising the... (Review)
Review
BACKGROUND
Methyl methacrylate monomer of denture base resins was modified with several monomers to achieve better physico-mechanical properties without compromising the biocompatibility. However, there are no consensuses on the best strategy to achieve best modified monomer.
PURPOSE
To identify and evaluate the differences in the properties between conventional and modified monomers and to verify the influence of several variables on the properties of denture base acrylic resin.
MATERIALS AND METHODS
This study was executed by following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. In-vitro studies that investigated the properties of conventional and modified monomers were selected. Searches were carried out in the Ebscohost, PubMed, Semantic scholar and J-stage databases. The search commenced from the year 1995 and the last search was done till November 2018. A comparison was performed between modified and unmodified monomers. The analyses were carried out using fixed-effect models.
RESULTS
The meta-analysis results showed high heterogeneity in all aspects, and higher flexural strength for monomers modified with 20% methacrylic acid.
CONCLUSION
Although the articles included in this meta-analysis showed high heterogeneity and high risk of bias, the in-vitro literature seems to suggest that use of modified monomers could improve the properties of denture base resins. Other variants of monomer modifications and their tested parameters were discussed in this systematic review as well. Dimensional accuracy is an unexplored variable to be evaluated extensively in the future researches.
PubMed: 31198322
DOI: 10.4103/JPBS.JPBS_34_19 -
Heliyon Feb 2021Prosthetic eyes are currently manufactured using Poly(methyl methacrylate) (PMMA) which is not an ideal material because it is hydrophobic. While significant research...
Prosthetic eyes are currently manufactured using Poly(methyl methacrylate) (PMMA) which is not an ideal material because it is hydrophobic. While significant research has investigated the benefits of hydrophilic materials for contact lenses, no such research has been carried out on hydrophilic materials for prosthetic eyes until now. In this study, different derivatives of Poly(ethylene glycol) (PEG) monomer and methyl methacrylate (MMA) monomer were grafted to PMMA using copolymerisation. The resulting matrixes were evaluated by water contact angle measurement, 24 h water absorption testing, and colour-difference measurement when exposed to ultraviolet light. The contact angle and water absorption results indicated that ethylene glycol dimethacrylate (EGDMA) grafted PMMA matrix had a better hydrophilic performance than the other matrixes tested. EGDMA is already a minor constituent of the PMMA matrix currently used for manufacturing prosthetic eyes but when the proportion of EGDMA monomer to MMA monomer used in the manufacturing process was increased to 50/50 the hydrophilicity of the matrix was significantly improved. EGDMA-grafted PMMA is inexpensive and comes as a liquid monomer that is easily mixed with the PMMA monomer that ocular prosthetists are familiar with. The mixture requires no special handling beyond the normal safety precautions that apply when using PMMA monomers. In-vitro testing shows that EGDMA-grafted PMMA significantly improves the wettability of PMMA currently used for the manufacture of prosthetic eyes and has the potential to significantly improve wearing comfort and socket health.
PubMed: 33665419
DOI: 10.1016/j.heliyon.2021.e06234 -
Biophysical Reviews Aug 2017Secondary nucleation of monomers on the surface of an already existing aggregate that is formed from the same kind of monomers may lead to autocatalytic amplification of... (Review)
Review
Secondary nucleation of monomers on the surface of an already existing aggregate that is formed from the same kind of monomers may lead to autocatalytic amplification of a self-assembly process. Such monomer-dependent secondary nucleation occurs during the crystallization of small molecules or proteins and self-assembled materials, as well as in protein self-assembly into fibrous structures. Indications of secondary nucleation may come from analyses of kinetic experiments starting from pure monomers or monomers supplemented with a low concentration of pre-formed aggregates (seeds). More firm evidence requires additional experiments, for example those employing isotope labels to distinguish new aggregates arising from the monomer from those resulting from fragmentation of the seed. In cases of amyloid formation, secondary nucleation leads to the formation of toxic oligomers, and inhibitors of secondary nucleation may serve as starting points for therapeutic developments. Secondary nucleation displays a high degree of structural specificity and may be enhanced by mutations or screening of electrostatic repulsion.
PubMed: 28812278
DOI: 10.1007/s12551-017-0289-z