Biodegradable Monomer Research Articles

Disubstituted cyclohexane monomers as biodegradable building block: Evaluation of biodegradability of polyesters containing cyclohexane ring

The introduction of cyclohexane rings endows polymers with excellent thermal and mechanical properties. Although cyclohexane rings have been incorporated into biodegradable polymers via copolymerization to improve their properties, their biodegradability has not been thoroughly investigated. In this study, we evaluated the biodegradability of ten cyclohexane ring-containing monomers as hydrolysates by biochemical oxygen demand (BOD) biodegradation testing to evaluate whether they can be used for biodegradable polyesters. These biodegradable monomers were polymerized with 1,4-butanediol and succinic acid to the corresponding polyesters containing cyclohexane rings. The biodegradability of these polyesters was investigated using clear-zone formation and BOD biodegradation testing. The clear-zone formation testing revealed the presence of microorganisms producing cyclohexane ring-containing polyester-degrading enzymes in eight polyesters with cyclohexane rings. Meanwhile, the respective polyesters did not exhibit BOD biodegradability despite the successful mineralization of the corresponding constituents. Overall, these findings indicate that the constituents exhibiting BOD biodegradability can be used as biodegradable building blocks.

Green Hydrogel Synthesis: Emphasis on Proteomics and Polymer Particle-Protein Interaction.

The field of drug discovery has seen significant progress in recent years. These advances drive the development of new technologies for testing compound's effectiveness, as well as their adverse effects on organs and tissues. As an auxiliary tool for drug discovery, smart biomaterials and biopolymers produced from biodegradable monomers allow the manufacture of multifunctional polymeric devices capable of acting as biosensors, of incorporating bioactives and biomolecules, or even mimicking organs and tissues through self-association and organization between cells and biopolymers. This review discusses in detail the use of natural monomers for the synthesis of hydrogels via green routes. The physical, chemical and morphological characteristics of these polymers are described, in addition to emphasizing polymer-particle-protein interactions and their application in proteomics studies. To highlight the diversity of green synthesis methodologies and the properties of the final hydrogels, applications in the areas of drug delivery, antibody interactions, cancer therapy, imaging and biomarker analysis are also discussed, as well as the use of hydrogels for the discovery of antimicrobial and antiviral peptides with therapeutic potential.

Clean polycondensation through mechanochemistry: Catalyst-free production of new urea-citric acid copolymer

The copolymerization reaction of biodegradable monomers urea and citric acid was performed for the first time via mechanochemistry using a planetary mill with controlled variables analysis (time and stirring velocity). The copolymer was characterized by Infrared Spectroscopy (FTIR), Matrix-Assisted Laser Desorption Ionization Process - (MALDI-TOF), X-ray Crystallography – XRC, Nuclear Magnetic Resonance – NMR, Thermogravimetry Analysis – TGA, Differential Scanning Calorimetry– DSC and Scanning Electron Microscopy – SEM. The polymeric material was produced involving a selective reaction of the terminal units of the carboxylic acids of citric acid with urea, and the central COOH remained intact. The copolymerization reaction was also investigated under solution condition with water as solvent, to compare the polymer production performance in both conditions. The yield of urea-citric copolymer under mechanochemistry condition (82%) is superior to the solution condition (70%). The product has low molecular weight, high crystallinity, and good thermal stability, and these two characteristics are superior to the mechanochemical product in comparison to that produced in solution. In this way, it was demonstrated a technologically feasible, catalyst and solvent-free clean route to produce urea-citric copolymer using mechanochemistry, without the formation of wastewater.

Physical properties of biomass-derived novel natural deep eutectic solvents based on choline chloride and (R)-3-hydroxyacids

We report the synthesis and physiochemical characterization of a series of Natural Deep Eutectic Solvents (NADESs), a subclass of ionic liquids that have demonstrated their potential as green solvents for widespread commercial application, including bio-safe chemical engineering technologies. The novel NADESs comprise of hydrogen bond donating (HBD) (R)-3-hydroxyalkanoic acids (R3HAs), biodegradable monomers of renewable polymer polyhydroxyalkanoate (PHA), and an appropriate conjugate hydrogen bond acceptor (HBA) species; namely choline chloride (ChCl). We combined theoretical and experimental methods to characterize a series of NADESs with increasing content of R3Has. Gas-phase theoretical modelling provided insight on potential hydrogen bond interactions between the components of the novel NADES and facilitated interpretation of their IR and H NMR spectra. The experiments revealed that the viscosity of R3HA:ChCl NADESs increased with decreasing temperature and increasing fraction of ChCl. The viscosity-temperature dependence was best described by a polynomial relationship; the Vogel-Tamman-Fulcher (VTF) model was also used but did not represent the empirical data, suggesting R3HA:ChCl NADES's viscosity-temperature behaviour is of non-Arrhenius type. Similarly, density was shown to increase with decreasing temperature and increasing ChCl fraction. In contrast to viscosity, the bonding ratio change was found to have little effect on density at a fixed temperature, other than the proportional increase associated with a higher fraction of the denser component. Solubility and wettability investigations concluded that R3HA:ChCl NADESs are compatible with mildly polar and hydrophobic solvents and as a result have a polarity index in the range 0–4.1.

Versatile, Highly Controlled Synthesis of Hybrid (Meth)acrylate–Polyester–Carbonates and their Exploitation in Tandem Post‐Polymerization–Functionalization

AbstractThe use of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) as a mild catalyst for the ring‐opening polymerization (ROP) of the pharma‐friendly and biodegradable monomer lactide and a functionalizable tert‐butyloxycarbonyl (BOC)‐protected cyclic carbonate is explored. Successful and controlled ROP is demonstrated when employing a series of labile‐ester (bis)(meth)acrylate initiators to produce macromonomers suitable for a range of post‐polymerization modifications. Importantly, the use of DBU ensured retention of the BOC group of the carbonate monomer during the polymerization, thus facilitating the production of highly functionalizable hybrid materials unobtainable using the more reactive triazabicyclodecene (TBD). Subsequently, a variety of short homo‐ and copolymers are synthesized with good control over material properties and final polymer composition. Successful attainment of these short copolymers confirm that DBU can overcome the previously observed limitations of TBD related to its kinetic competition between ROP and transesterification side‐reactions under these reaction conditions. Furthermore, the fidelity of the hydroxyl and (meth)acrylic end groups are maintained as confirmed by a series of secondary tandem reactions. The macromonomers are also utilized in reversible addition−fragmentation chain‐transfer polymerization (RAFT) polymerization for the production of amphiphilic block or random copolymers with a hydrophilic comonomer, poly(ethyleneglycol)methacrylate. The amphiphilic copolymers produced via the tandem RAFT reaction demonstrate the ability to self‐assemble into monodisperse nanoparticles in aqueous environments.

Effect of Chemical Composition Variant and Oxygen Plasma Treatments on the Wettability of PLGA Thin Films, Synthesized by Direct Copolycondensation.

The synthesis of high molecular weight poly (lactic-co-glycolic) acid (PLGA) copolymers via direct condensation copolymerization is itself a challenging task. Moreover, some of the characteristic properties of polylactide (PLA)-based biomaterials, such as brittleness, hydrophobicity, and longer degradation time, are not suitable for certain biomedical applications. However, such properties can be altered by the copolymerization of PLA with other biodegradable monomers, such as glycolic acid. A series of high molecular weight PLGAs were synthesized through the direct condensation copolymerization of lactic and glycolic acids, starting from 0 to 50 mol% of glycolic acid, and the wettability of its films was monitored as a function of the feed molar ratio. Copolymerization was performed in the presence of a bi-catalytic system using stannous chloride dihydrate and methanesulfonic acid (MSA). The viscosity average molecular weight of the resulting PLGA was in the range of 80k to 135k g/mol. The PLGA films were prepared using the solvent casting technique, and were treated with oxygen plasma for 2 min. The water contact angle of the PLGA films was determined before and after the oxygen plasma treatments, and it was observed that the wettability increased with an increase in the glycolic acid contents, however, the manifolds increased after 2 min of oxygen plasma treatments.

Biodegradability of polyesters comprising a bio-based monomer derived from furfural

Development of novel biodegradable monomers is indispensable for affording high-performance biodegradable polymers. In addition, a monomer that is synthesized from biomass is preferable as this enhances the overall sustainability of the resulting biodegradable polymer. Bio-based polyoxabicyclates (POBCs) comprising oxabicyclodicarboxylic anhydride (OBCA), which are flexible and transparent materials, were derived from an inedible bio-based chemical, i.e. furfural. Herein, we evaluated the biodegradability of the POBCs using biochemical oxygen demand (BOD)-biodegradation testing and the clear-zone formation method. We observed that the environmental biodegradability of the POBCs depended on the length of diol methylene units. The BOD biodegradabilities of POBCs comprising 1,3-propanediol, 1,4-butanediol, and 1,10-decanediol were more than 85%. Furthermore, two bacteria formed a clear zone on the emulsified medium containing POBC with 1,4-butanediol. These results indicated that OBCA could be adopted as a novel biodegradable monomer.

Facile synthesis of thiol-functionalized amphiphilic polylactide–methacrylic diblock copolymers

Biodegradable amphiphilic diblock copolymers based on an aliphatic ester block and various hydrophilic methacrylic monomers were synthesized using a novel hydroxyl-functionalized trithiocarbonate-based chain transfer agent. One protocol involved the one-pot simultaneous ring-opening polymerization (ROP) of the biodegradable monomer (3S)-cis-3,6-dimethyl-1,4-dioxane-2,5-dione (L-lactide, LA) and reversible addition–fragmentation chain transfer (RAFT) polymerization of 2-(dimethylamino)ethyl methacrylate (DMA) or oligo(ethylene glycol) methacrylate (OEGMA) monomer, with 4-dimethylaminopyridine being used as the ROP catalyst and 2,2′-azobis(isobutyronitrile) as the initiator for the RAFT polymerization. Alternatively, a two-step protocol involving the initial polymerization of LA followed by the polymerization of DMA, glycerol monomethacrylate or 2-(methacryloyloxy)ethyl phosphorylcholine using 4,4′-azobis(4-cyanovaleric acid) as a RAFT initiator was also explored. Using a solvent switch processing step, these amphiphilic diblock copolymers self-assemble in dilute aqueous solution. Their self-assembly provides various copolymer morphologies depending on the block compositions, as judged by transmission electron microscopy and dynamic light scattering. Two novel disulfide-functionalized PLA-branched block copolymers were also synthesized using simultaneous ROP of LA and RAFT copolymerization of OEGMA or DMA with a disulfide-based dimethacrylate. The disulfide bonds were reductively cleaved using tributyl phosphine to generate reactive thiol groups. Thiol–ene chemistry was utilized for further derivatization with thiol-based biologically important molecules and heavy metals for tissue engineering or bioimaging applications, respectively.

Biodegradable elastomers based on ABA triblocks: influence of end‐block crystallinity on elastomeric character

AbstractABA triblock copolymers, based on biodegradable monomers, namely ε‐caprolactone (CL) and L‐lactide (LLA), were synthesized and studied. The end‐blocks were mostly poly(L‐lactide) while the middle segments were a random copolymer of PCL and PLLA. Synthesis of these copolymers was performed by varying the end‐block segment length while retaining a fixed middle‐block segment length and vice versa. Nuclear magnetic resonance studies confirmed the designed structure of the copolymers and their thermal properties were studied with differential scanning calorimetry. Mechanical and thermomechanical properties were determined with an Instron tester and by dynamic mechanical analysis, respectively. The elastomeric character of the copolymers was verified by cyclic test as well as by creep and recovery measurements. Changes made to the middle‐ and end‐block segment lengths had a significant influence on the mechanical properties of the copolymers, especially their extendibility and recoverability. An increase in the crystallinity of the end‐blocks in the copolymers caused a drop in their elastomeric character. In cyclic testing, under conditions of 50% and 150% strain, copolymers with low end‐block crystallinity could recover more than 85% whereas copolymers with high crystallinity showed reduced recovery values as low as 60%. Copyright © 2011 Society of Chemical Industry

Biodegradable pH- and temperature-sensitive multiblock copolymer hydrogels based on poly(amino-ester urethane)s

A novel pH- and temperature-responsive multiblock copolymer consisting of poly(ethylene glycol) (PEG) and poly(amino-ester urethane) (PAEU) is reported. First, a biodegradable monomer, bis-1,4-(hydroxyethyl)piperazine mono-lactate (HEP mono-lactate), was synthesized by the ring-opening polymerization of D,L-lactide (LA) using HEP and Sn(Oct)2 as an initiator and catalyst, respectively. The multiblock copolymers were synthesized further from PEG, HEP, HEP mono-lactate, and 1,6-diisocyanatohexamethylene (HDI) in the presence of dibutyltin dilaurate as a catalyst. The resulting copolymers were characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). At pH 6.8 or higher, the copolymer aqueous solutions showed gel-to-sol transitions with increasing temperature, and the gel window covered the physiological conditions. After a subcutaneous injection of the multiblock copolymer solution into SD rats, a soft gel was formed in a short time. The degradability of the copolymer was adjusted by varying the LA content in the PAEU block.

Biocompatible Phosphorus-based Monomers for Radical Polymerization

AbstractNovel biocompatible and biodegradable monomers based on phosphorus-containing vinyl esters and vinyl carbamates for radical photopolymerization were prepared. By photo-Differential Scanning Calorimetry (photo-DSC) the reactivity of the mono-, di- and trifunctional monomers was investigated. Furthermore, their cytotoxicity, mechanical properties and hydrolytic degradation behavior were evaluated, aiming at a future application of our compounds in the biomedical area.

Nanostructured Biodegradable Polymer Networks Using Lyotropic Liquid Crystalline Templates

The physical properties, porosity, and physiological behavior of synthetic biodegradable hydrogels have been identified as highly critical design parameters in most tissue engineering materials applications. Nanotechnology may provide the means to manipulate these parameters by accessing control over the network structure of the biomaterial, providing unique property relationships that often result from nanostructured materials. In this study, a lyotropic liquid crystal (LLC) was used as a polymerization template in the formation of a photopolymerizable biodegradable PLA-b-PEG-b-PLA (PEG = poly(ethylene glycol); PLA = poly(lactic acid)) material with nanoscale lamellar morphology. Through ordering of the biodegradable monomer within the liquid crystal assembly, a 2-fold increase in maximum polymerization rate and a 30% increase in double bond conversion were realized over isotropic monomer formulations. The resulting network structure of the templated PLA-b-PEG-b-PLA material has a dramatic affect on the physical properties of the hydrogel including an 80% increase in network swelling and an approximately 230% increase in diffusivity. This increase in permeability and solvent uptake leads to rapid degradation of the lamellar templated samples, further demonstrating the influence of the LLC directed network structure on the porosity and physical properties of the biodegradable material. The ability to control the porosity, physical properties, and behavior of a biodegradable hydrogel simply by imparting LLC network structure, without changing the chemistry or biocompatibility of the polymer, could prove highly advantageous in the design of synthetic biomaterials for potential medical applications.

Protective efficiency of dendrosomes as novel nano-sized adjuvants for DNA vaccination against birch pollen allergy

We evaluated the use of a novel gene porter (Den123--a nontoxic self-assembled dendritic spheroidal nanoparticle made of biodegradable monomers), aiming to enhance and improve the desired immune response in protection from allergy. Footpad DNA immunization in Balb/c mice was done three times using the Bet v 1a gene with or without Den123 with 2-week intervals followed by sensitization with rBetv1 (5 microg) in alum twice in a weekly interval. Different doses of pCMV-Betv1 were used (10 microg and 100 microg). The protective role of different formulations was evaluated by measuring the IgG1, IgG2a and IgE antibody production, cytokine release of isolated splenocytes and beta-hexosaminidase release from the RBL cells. Higher and increasing ratios of IgG2a/IgG1 were seen in mice which received plasmids in combination with Den123. Den123 and DNA vaccine synergistically enhanced the Interferon gamma released from splenocytes. In the presence of Den123, IgE inhibition was independent of the dose and type of the injected DNA. All DNA-pre-immunized mice demonstrated low basophil degranulation. It is therefore concluded that administration of the DNA entrapped in Den123 nanoparticles results in sustained release of plasmids, Th1/Th2 balanced immune response with promising IgE inhibition. Also higher amounts of DNA contributed to stronger Th1 response.

Surface modification of polyvinyl chloride with biodegradable monomers

Graft copolymerization of sucrose acrylate (SA) onto 55 μm films of poly(vinyl chloride) (PVC) was investigated with benzophenone or 2,2′-azoisobutironitrile as the initiator. The grafting reactions were carried out in a closed cell containing the films to be treated with a solution of the sensitizer and the monomer. In this system, ultraviolet light through a quartz window initiated the reaction by exciting the initiator used. The grafting took place on a PVC surface layer, from the solution. The homopolymer formed during copolymerization was removed by washing. The percentage of grafting was determined by gravimetric measurements and by dye adsorption (crystal violet), and the characterization of PVC(g)SA was carried out by the use of infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis. The weathering behavior of PVC(g)SA was studied with microorganisms in a growing medium, and the degradation was monitored by the weight loss of the films, FTIR, and SEM. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1195–1201, 1997

Surface modification of polyvinyl chloride with biodegradable monomers

Surface modification of polyvinyl chloride with biodegradable monomers