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The interaction of poly(trimethylene carbonate) (PTMC) with hydroxyl group compounds was investigated as a model for polymer blending with polysaccharides. While 1-butanol, 2-butanol, ethylene glycol, and 1,2-cyclohexanediol showed almost no detectable interaction with PTMC in both solution states with the 1H NMR and solid states with the FT-IR, glucose and cellobiose suggested a slight change in the spectral pattern in FT-IR analysis. The thermal properties of the blended samples of PTMC and these hydroxyl groups were also investigated. Although the blends of PTMC with 1-butanol and 2-butanol did not influence thermal degradation behaviors due to their low boiling points, the PTMC blend with a higher number of hydroxyl groups, especially glucose and cellobiose, tended to increase thermal resistance and glass transition temperature, hence showing the existence of an interaction through hydrogen bonding. [ABSTRACT FROM AUTHOR]

The interaction of poly(trimethylene carbonate) (PTMC) with hydroxyl group compounds was investigated as a model for polymer blending with polysaccharides. While 1-butanol, 2-butanol, ethylene glycol, and 1,2-cyclohexanediol showed almost no detectable interaction with PTMC in both solution states with the 1H NMR and solid states with the FT-IR, glucose and cellobiose suggested a slight change in the spectral pattern in FT-IR analysis. The thermal properties of the blended samples of PTMC and these hydroxyl groups were also investigated. Although the blends of PTMC with 1-butanol and 2-butanol did not influence thermal degradation behaviors due to their low boiling points, the PTMC blend with a higher number of hydroxyl groups, especially glucose and cellobiose, tended to increase thermal resistance and glass transition temperature, hence showing the existence of an interaction through hydrogen bonding.

Introduction: Poly(1,3-trimethylene carbonate) (PTMC) is a flexible amorphous polymer with good degradability and biocompatibility. The degradation of PTMC is critical for its application as a degradable polymer, more convenient and easy-to-control cross-linking strategies for preparing PTMC are required.Methods: The blends of poly(trimethylene carbonate) (PTMC) and cross-linked poly(ethylene glycol) diacrylate (PEGDA) were prepared by mixing photoactive PEGDA and PTMC and subsequently photopolymerizing the mixture with uv light. The physical properties and in vitro enzymatic degradation of the resultant PTMC/cross-linked PEGDA blends were investigated.Results: The results showed that the gel fraction of PTMC/cross-linked PEGDA blends increased while the swelling degree decreased with the content of PEGDA dosage. The results of in vitro enzymatic degradation confirmed that the degradation of PTMC/cross-linked PEGDA blends in the lipase solution occurred under the surface erosion mechanism, and the introduction of the uv cross-linked PEGDA significantly improved the resistance to lipase erosion of PTMC; the higher the cross-linking degree, the lower the mass loss.Discussion: The results indicated that the blends/cross-linking via PEGDA is a simple and effective strategy to tailor the degradation rate of PTMC.

The encapsulation and release of hydrophobic drugs from polymersomes are of great importance in drug delivery. A significant challenge is to enhance the encapsulation capacity of finding better drug-polymer compatibility. Herrin, poly(trimethylene carbonate)- b-poly(ethylene glycol) (PTMC-PEG) diblock copolymers were successfully synthesized by ring opening polymerization of trimethylene carbonate using monomethoxy poly(ethylene glycol) (mPEG) as macro-initiator and stannous octoate as catalyst. The resulting diblock copolymer were characterized by 1H NMR, FTIR, GPC, and DSC techniques. Blank and paclitaxel (PTX) loaded micelles was prepared by cosolvent evaporation method and characterized by transmission electron microscope (TEM) and dynamic light scattering (DLS). The influence of hydrophilic/hydrophobic segment length to drug loading and release was explored. All micelles have the sustained hydrophobic drug release properties of the micelles. Moreover, the cytotoxicity of micelles was evaluated by MTT and live-dead cell staining assay using L929 cell lines, showing the good biocompatibility. Therefore, PTMC-PEG micelles could be a suitable material for the loading and releasing of hydrophobic drugs. [ABSTRACT FROM AUTHOR]

Poly(L-lactide) (PLLA) and PLLA/poly(trimethylene carbonate) (PTMC) scaffolds characterised by different PLLA:PTMC mass ratios (10:0, 9:1, 8:2, 7:3, 6:4 and 5:5) were prepared via electrospinning. The results showed that increasing the PTMC content in the spinning solution caused the following effects: (1) the diameter of the prepared PLLA/PTMC electrospun fibres gradually increased from 188.12 ± 48.87 nm (10:0) to 584.01 ± 60.68 nm (5:5), (2) electrospun fibres with uniform diameters and no beads could be prepared at the PTMC contents of >30%, (3) the elastic modulus of the fibre initially increased and then decreased, reaching a maximum value of 74.49 ± 8.22 Mpa (5:5) and (4) the elongation at the breaking point of the fibres increased gradually from 24.71% to 344.85%. Compared with the PLLA electrospun fibrous membrane, the prepared PLLA/PTMC electrospun fibrous membrane exhibited considerably improved mechanical properties while maintaining good histocompatibility. [ABSTRACT FROM AUTHOR]

[Display omitted] A review. Poly(trimethylene carbonate) (PTMC) is well known as synthetic degradable polymer, featuring carbonate groups in its main chain backbone. Numerous studies have investigated its polymerization kinetics using various catalysts, copolymer compositions, and derivatives for functional polymer applications. This review highlights recent research on polymer blends involving PTMC, with a specific focus on their diverse applications. [ABSTRACT FROM AUTHOR]

Amphiphilic block copolymers based on poly(trimethylene carbonate) (PTMC) have gained significant attention for biomedical applications owing to their unique degradation characteristics. Ring-opening polymerization (ROP) is the most widely employed method for polymerization of cyclic carbonates, especially for trimethylene carbonate (TMC). Herein, di- and tri-block copolymers of PTMC are synthesized by ROP of TMC using poly(ethylene glycol) monomethyl ether (MeO-PEG) or poly(ethylene glycol) (PEG) as a macro-initiator, respectively. The synthesized products are characterized by size-exclusion chromatography (SEC) and nuclear magnetic resonance spectroscopy (1H NMR) for their molar mass and chemical composition, respectively. However, these techniques are inconclusive about several pertinent aspects of the block copolymers, such as individual block length and unwanted homopolymer content. To address these limitations, liquid chromatography at critical conditions of both PEG and PTMC are employed. Chromatographic critical conditions for PTMC are reported for the first time in the current study. The analysis protocol successfully reveals the individual block lengths of both blocks of the block copolymers, along with the quantification of the unwanted homopolymers in the samples. The individual block lengths and the presence of homopolymers significantly affect the self-assembly capability and drug-loading capacity of amphiphilic block copolymers. Thus, the study divulges important information crucial for the development of structure-property correlations, which is essential for optimizing the performance of these block copolymers in biomedical applications. [Display omitted] • Ring-opening polymerization of trimethylene carbonate. • Di- and tri-block copolymers of PEG and PTMC. • Analysis by liquid chromatography at critical conditions. • Critical conditions of PTMC are reported for the first time. • Analysis protocol revealed individual block lengths and unwanted homopolymer content of the samples. [ABSTRACT FROM AUTHOR]

In this study, poly (trimethylene carbonate) (PTMC) with excellent biocompatibility was synthesized via ring-opening of TMC to prepare the Ciprofloxacin-loaded PTMC implants, and antibacterial effects in vitro or in vivo of the resulting implants were investigated to evaluate the potential for treating chronic osteomyelitis. The in vitro results showed the Ciprofloxacin-loaded PTMC implants could sustain release ciprofloxacin at a release amount of about 90 μg/d for 28 days and possessed excellent antibacterial effect, as evidenced by the smaller size of the antibacterial ring of 32.6 ± 0.64 mm and the biofilm inhibition of 60% after 28 days of release. The in vivo results showed that after 28 days of treatment, the body weight and the white blood cell counts of chronic-osteomyelitis-model rats in the treatment group reached 381.6 ± 16.8 g and (7.86 ± 0.91) ×109/L, respectively, returning to normal rapidly compared with the control and blank group, indicating the remarkable antibacterial effect of the Ciprofloxacin-loaded PTMC implants. X-ray images and HE staining results also confirmed that most of the proximal and middle parts of the tibia returned to typical structures and new and trabecular bone had been formed for the rats in the treatment group, and no inflammatory cells were found as compared to the control and blank groups, after 28 days of treatment. The significant lower number of colonies of (9.92 ± 1.56) × 10 CFU/g in the treatment group also suggests that the Ciprofloxacin-loaded PTMC implants achieve a practical antibacterial effect through a local application.

The paper presents the synthesis and characterization of poly(trimethylene carbonate) grafted chitosan as a new water soluble biopolymer suitable for in vivo applications. The synthesis was performed via ring-opening polymerization of 1,3-dioxan-2-one (trimethylene carbonate) (TMC) monomer, initiated by the functional groups of chitosan in the presence of toluene as solvent/swelling agent. By varying the molar ratio between the glucosamine units of chitosan and TMC, a series of chitosan derivatives with different content of poly(trimethylene carbonate) chains was synthetized. The structural characterization of the polymers was realized by FTIR and 1H NMR spectroscopy and their solubility was assessed in water and in organic solvents as well. The biocompatibility was investigated by MTS assay on Normal Human Dermal Fibroblasts, and the biodegradability was evaluated in lysozyme buffer solution. Further, the surface properties of the polymer films were analyzed by polarized optical microscopy, atomic force microscopy and water-to-air contact angle measurements. It was established that, by 5% substitution of chitosan with poly(trimethylene carbonate) chains having an average polymerization degree of 7, a water soluble polymer can be attained. Compared to the pristine chitosan, it has improved biocompatibility in solution and moderate wettability and higher biodegradability rate in solid state, pointing its suitability for in vivo applications. [ABSTRACT FROM AUTHOR]

Xing Li1,2 ,* Honglin Chen3 ,* Shuting Xie,1,2 Ning Wang,3 Sujuan Wu,1,2 Yuyou Duan,3 Minmin Zhang,4 Lingling Shui1,2,4 1National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, People’s Republic of China; 2Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, People’s Republic of China; 3Institute for Life Science, School of Medicine, South China University of Technology, Guangzhou 510006, People’s Republic of China; 4School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006, People’s Republic of China*These authors contributed equally to this workCorrespondence: Minmin Zhang; Lingling Shui Tel +86-20-39310508; +86-20-39310309; Email zhangminmin@m.scnu.edu.cn; shuill@m.scnu.edu.cnBackground: The treatment of tendon injuries remains a challenging problem in clinical due to their slow and insufficient natural healing process. Scaffold-based tissue engineering provides a promising strategy to facilitate tendon healing and regeneration. However, many tissue engineering scaffolds have failed due to their poor and unstable mechanical properties. To address this, we fabricated nanofibrous polycaprolactone/methacrylated poly(trimethylene carbonate) (PCL/PTMC-MA) composite scaffolds via electrospinning.Materials and Methods: PTMC-MA was characterized by nuclear magnetic resonance. Fiber morphology of composite scaffolds was evaluated using scanning electron microscopy. The monotonic tensile test was performed for determining the mechanical properties of composite scaffolds. Cell viability and collagen deposition were assessed via PrestoBlue assay and enzyme-linked immunosorbent assay, respectively.Results: These PCL/PTMC-MA composite scaffolds had an increase in mechanical properties as PTMC-MA content increase. After photo-crosslinking, they showed further enhanced mechanical properties including creep resistance, which was superior to pure PCL scaffolds. It is worth noting that photo-crosslinked PCL/PTMC-MA (1:3) composite scaffolds had a Young’s modulus of 31.13 ± 1.30 MPa and Max stress at break of 23.80 ± 3.44 MPa that were comparable with the mechanical properties of native tendon (Young’s modulus 20– 1200 MPa, max stress at break 5– 100 MPa). In addition, biological experiments demonstrated that PCL/PTMC-MA composite scaffolds were biocompatible for cell adhesion, proliferation, and differentiation.Keywords: poly(trimethylene carbonate), composite scaffolds, tissue engineering, photo-crosslinking, creep resistance

Biodegradable poly(carbonate anhydrides) based on poly(trimethylene carbonate) were synthesized by ring-opening polymerization. The hydroxyl-terminated oligomers were acid-functionalized with succinic anhydride and subsequently methacrylated to obtain photo-crosslinkable three-armed macromers with anhydride bonds. The degree of acid-functionalization was over 96%, and the degree of methacrylation was over 80%. The macromers were photo-crosslinked into networks at room temperature in a nitrogen atmosphere. In vitro degradation experiments in phosphate-buffered solution (pH 7.4) at 37 °C showed that the networks degraded rapidly with complete mass loss within 72 h. For networks prepared from the higher molecular weight, the presence of an alkenyl chain in the anhydride bond resulted in lower water uptake and consequently in a decrease in the degradation rate. The degradation mechanism of these networks showed characteristics of surface erosion.

To more precisely control the degradation rate of poly(trimethylene carbonate) (PTMC), self-blending films were prepared via the ternary self-blending of pure PTMC with a molecular weight of 334, 152, and 57 kg/mol. The in vitro enzymolysis degradation of the ternary self-blending films was performed in lipase solutions. The results showed that ternary self-blending could control the degradation of PTMC by adjusting the mass ratio of high/medium/low molecular weight PTMC in the composition, and the PTMC334/PTMC152/PTMC57 films with a mass ratio of 1/4/16 showed mass loss of 85.96% after seven weeks of degradation, while that of PTMC334/PTMC152/PTMC57 films with a mass ratio of 1/1/1 was 96.39%. The former and latter’s degradation rate constant was 13.263 and 23.981%/w, respectively, and the former presented better morphology stability than the latter. The strategy of ternary self-blending could simultaneously bestow PTMC with a lower degradation rate and good morphology stability, indicating that ternary self-blending is an efficient way to control the degradation performance of PTMC more precisely.

Poly(L-lactide) (PLLA) and PLLA/poly(trimethylene carbonate) (PTMC) scaffolds characterised by different PLLA:PTMC mass ratios (10:0, 9:1, 8:2, 7:3, 6:4 and 5:5) were prepared via electrospinning. The results showed that increasing the PTMC content in the spinning solution caused the following effects: (1) the diameter of the prepared PLLA/PTMC electrospun fibres gradually increased from 188.12 ± 48.87 nm (10:0) to 584.01 ± 60.68 nm (5:5), (2) electrospun fibres with uniform diameters and no beads could be prepared at the PTMC contents of >30%, (3) the elastic modulus of the fibre initially increased and then decreased, reaching a maximum value of 74.49 ± 8.22 Mpa (5:5) and (4) the elongation at the breaking point of the fibres increased gradually from 24.71% to 344.85%. Compared with the PLLA electrospun fibrous membrane, the prepared PLLA/PTMC electrospun fibrous membrane exhibited considerably improved mechanical properties while maintaining good histocompatibility.

Mechanochemical polymerization is a rapidly growing area and a number of polymeric materials can now be obtained through green mechanochemical synthesis. In addition to the general merits of mechanochemistry, such as being solvent-free and resulting in high conversions, we herein explore rate acceleration under ball-milling conditions while the conventional solution-state synthesis suffer from low reactivity. The solvent-free mechanochemical polymerization of trimethylene carbonate using the organocatalysts 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) are examined herein. The polymerizations under ball-milling conditions exhibited significant rate enhancements compared to polymerizations in solution. A number of milling parameters were evaluated for the ball-milling polymerization. Temperature increases due to ball collisions and exothermic energy output did not affect the polymerization rate significantly and the initial mixing speed was important for chain-length control. Liquid-assisted grinding was applied for the synthesis of high molecular weight polymers, but it failed to protect the polymer chain from mechanical degradation.

Three-armed poly(trimethylene carbonate) (PTMC) and poly(trimethylene carbonate-co-Ɛ-caprolactone) (P(TMC-co-ε-CL)) macromers with molecular weights of approximately 30 kg mol -1 are synthesized by ring-opening polymerization and subsequent functionalization with methacrylic anhydride. Networks are then prepared by photo-crosslinking. To investigate the in vitro and in vivo degradation properties of these photo-crosslinked networks and assess the effect of ε-caprolactone content on the degradation properties, PTMC networks, and copolymer networks with two different TMC:ε-CL ratios are prepared. PTMC networks degraded slowly, via an enzymatic surface erosion process, both in vitro and in vivo. Networks prepared from P(TMC-co-ε-CL) macromers with a 74:26 ratio are found to degrade slowly as well, via a surface erosion process, albeit at a higher rate compared to PTMC networks. Increasing the ε-CL content to a ratio of 52:48, resulted in a faster degradation. These networks lost their mechanical properties much sooner than the other networks. Thus, PTMC and P(TMC-co-ε-CL) networks are interesting networks for tissue engineering purposes and the exact degradation properties can be tuned by varying the TMC:ε-CL ratio, providing researchers with a tool to obtain copolymer networks with the desired degradation rate depending on the intended application., (© 2023 The Authors. Macromolecular Bioscience published by Wiley-VCH GmbH.)

Cochlear implantation (CI) is the primary intervention for patients with sensorineural hearing loss to restore their hearing. However, approximately 90 % of CI recipients experience unexpected fibrosis around the inserted electrode arrays due to acute and chronic inflammation. This fibrosis leads to progressive residual hearing loss. Addressing this complication is crucial for enhancing CI outcomes, yet an effective treatment has not yet been found. In this study, we developed a multifunctional dexamethasone (DXM)-loaded polytrimethylene carbonate (PTMC) electrode coating to mitigate inflammatory reactions and fibrosis after CI. This thin and flexible coating could preserve the mechanical performance of the electrode and reduce the implantation resistance for CI. The in vitro release studies demonstrated the DXM-PTMC coating's efficient drug loading and sustained release capability over 90 days. DXM-PTMC also showed long-term stability, high biocompatibility, and effective anti-inflammatory effects in vitro and in vivo. Compared with the uncoated group, DXM-PTMC coating significantly inhibited the expression of inflammatory factors, such as NO, TNF-α, IL-1β, and IL-6. DXM-PTMC coating suppressed fibrosis in rat implantation models for 3 weeks by reducing both acute and chronic inflammation. Our findings suggest that DXM-PTMC coating is a novel strategy to improve the outcomes of CI., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2023. Published by Elsevier B.V.)

Xi Zhang,1,2 Mike A Geven,3 Xinluan Wang,4 Ling Qin,4 Dirk W Grijpma,3 Ton Peijs,1 David Eglin,5 Olivier Guillaume,5 Julien E Gautrot1,2 1School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, UK; 2Institute of Bioengineering, Queen Mary University of London, Mile End Road, London, UK; 3Department of Biomaterials Science and Technology, University of Twente, Enschede, the Netherlands; 4Translational Medicine R&D Center, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 5018057, China; 5AO Research Institute Davos, Davos, Switzerland Background: Poly(trimethylene carbonate) (PTMC) has wide biomedical applications in the field of tissue engineering, due to its biocompatibility and biodegradability features. Its common manufacturing involves photofabrication, such as stereolithography (SLA), which allows the fabrication of complex and controlled structures. Despite the great potential of SLA-fabricated scaffolds, very few examples of PTMC-based drug delivery systems fabricated using photofabrication can be found ascribed to light-triggered therapeutics instability, degradation, side reaction, binding to the macromers, etc. These concerns severely restrict the development of SLA-fabricated PTMC structures for drug delivery purposes. Methods: In this context, we propose here, as a proof of concept, to load a drug model (dexamethasone) into electrospun fibers of poly(lactic acid), and then to integrate these bioactive fibers into the photo-crosslinkable resin of PTMC to produce hybrid films. The hybrid films’ properties and drug release profile were characterized; its biological activity was investigated via bone marrow mesenchymal stem cells culture and differentiation assays. Results: The polymer/polymer hybrids exhibit improved properties compared with PTMC-only films, in terms of mechanical performance and drug protection from UV denaturation. We further validated that the dexamethasone preserved its biological activity even after photoreaction within the PTMC/poly(lactic acid) hybrid structures by investigating bone marrow mesenchymal stem cells proliferation and osteogenic differentiation. Conclusion: This study demonstrates the potential of polymer–polymer scaffolds to simultaneously reinforce the mechanical properties of soft matrices and to load sensitive drugs in scaffolds that can be fabricated via additive manufacturing. Keywords: fiber-reinforced composite, poly(trimethylene carbonate), photo-crosslinking, dexamethasone, osteogenic materials

Biodegradable poly(carbonate anhydrides) based on poly(trimethylene carbonate) were synthesized by ring-opening polymerization. The hydroxyl-terminated oligomers were acid-functionalized with succinic anhydride and subsequently methacrylated to obtain photo-crosslinkable three-armed macromers with anhydride bonds. The degree of acid-functionalization was over 96%, and the degree of methacrylation was over 80%. The macromers were photo-crosslinked into networks at room temperature in a nitrogen atmosphere. In vitro degradation experiments in phosphate-buffered solution (pH 7.4) at 37 °C showed that the networks degraded rapidly with complete mass loss within 72 h. For networks prepared from the higher molecular weight, the presence of an alkenyl chain in the anhydride bond resulted in lower water uptake and consequently in a decrease in the degradation rate. The degradation mechanism of these networks showed characteristics of surface erosion. [ABSTRACT FROM AUTHOR]

Telechelic poly(trimethylene carbonate) (PTMC) oligomers are synthesized and carefully characterized with molar masses between 300 and 5000 g mol−1 in bulk by ring‐opening polymerization (ROP) with 1,3‐dioxan‐2‐one (trimethylene carbonate or TMC) as monomer and 1,4‐butanediol (BDO) as co‐initiator. 1,5,7‐Triazabicyclo[4.4.0]dec‐5‐ene (TBD) organic catalyst and tin(II) bis(2‐ethylhexanoate) (Sn(Oct)2) organometallic initiator are chosen comparatively. Due to the bi‐functionality of BDO and relatively low TMC/BDO feed ratios, it is proved that PTMC chains are elaborated from one or both the BDO alcohol functions, producing two coexisting kinds of PTMC chains with BDO unit at the chain end or in the backbone. Additionally, PTMC chains bear permanent and fast exchange reactions at 100 °C, leading to both a dynamic redistribution of chains and their extension with BDO unit numbers mainly from 0‐4 but up to 6. Longer reaction times and lower TMC/BDO molar ratios bring about more predominant exchange reactions and MALDI‐TOF allows to detail the structures evolutions deeply. Better average molar masses control and narrower distributions are obtained with TBD as compared to Sn(Oct)2. PTMC molar masses can be predicted simply by the TMC/BDO feed ratio with TBD. Kinetically, TBD is the most efficient. The glass transition temperature Tg is found to respect Flory–Fox model. [ABSTRACT FROM AUTHOR]

PTMC-PEG-PTMC triblock copolymers were prepared by ring-opening polymerization of trimethylene carbonate (TMC) in the presence of dihydroxylated poly(ethylene glycol) (PEG) with Mn of 6000 and 10,000 as macro-initiator. The copolymers with different PTMC block Lengths and the two PEGs were end functionalized with acryloyl chloride. The resulting diacrylated PEG-PTMC-DA and PEG-DA were characterized by using NMR, GPC and DSC. The degree of substitution of end groups varied from 50.0 to 65.1%. Hydrogels were prepared by photo-crosslinking PEG-PTMC-DA and PEG-DA in aqueous solution using a water soluble photo-initiator under visible light irradiation. The effects of PTMC and PEG block lengths and degree of substitution on the swelling and weight loss of hydrogels were determined. Higher degree of substitution leads to higher crosslinking density, and thus to lower degree of swelling and weight loss. Similarly, higher PTMC block length also leads to lower degree of swelling and weight loss. Freeze dried hydrogels exhibit a highly porous structure with pore sizes from 20 to 100 µm. The biocompatibility of hydrogels was evaluated by MTT assay, hemolysis test, and dynamic clotting time measurements. Results show that the various hydrogels present outstanding cyto- and hemo-compatibility. Doxorubicin was taken as a model drug to evaluate the potential of PEG-PTMC-DA and PEG-DA hydrogels as drug carrier. An initial burst release was observed in all cases, followed by slower release up to more than 90%. The release rate is strongly dependent on the degree of swelling. The higher the degree of swelling, the faster the release rate. Finally, the effect of drug loaded hydrogels on SKBR-3 tumor cells was evaluated in comparison with free drug. Similar cyto-toxicity was obtained for drug loaded hydrogels and free drug at comparable drug concentrations. Therefore, injectable PEG-PTMC-DA hydrogels with outstanding biocompatibility and drug release properties could be most promising as bioresorbable carrier of hydrophilic drugs. [ABSTRACT FROM AUTHOR]

The application of 3D printing by fused deposition modeling (FDM) and the low-cost RepRap 3D printer for the processing of poly-l-lactide (PLLA) and poly(l-lactide-co-trimethylene carbonate) (PLLATMC) blends was examined. Two blends with different mechanical properties were selected and the general scheme of their processing was proposed. For 80:20 PLLA:PLLATMC blend, fused filament fabrication (FFF) and the standard configuration of 3D printer were used, whereas for 30:70 PLLA:PLLATMC, the device was modified based on custom project for the application of fused granulate fabrication (FGF). The properties of the blends and their changes during the processing were analyzed by rheological measurements and size exclusion chromatography. Selected parameters of the printing process were optimized and their influence on the quality of the product was discussed. Both methods were used for the preparation of the scaffolds with different previously designed structures. The geometry of the scaffolds was characterized in relation to the parameters of the printing process, and base on this, the accuracy and precision of FFF and FGF methods were evaluated. [ABSTRACT FROM AUTHOR]

In this work was evaluated the activity of samarium acetate (III) (Sm(OAc)3) as a possible initiator in the polymerization by ring opening of trimethylene carbonate (TMC). All polymerizations were carried out under solvent-free melt conditions in ampoules-like flasks, equipped with a magnetic stirrer. The effects of different parameters of reaction, such as molar ratio monomer to initiator, temperature and reaction time, on typical variables of polymers, e.g., conversion of TMC to poly(trimethylene carbonate) (PTMC), dispersity and molar mass, were analyzed. The molar ratio of monomer to initiator was varied between 0 and 1000 mol/mol and the temperature among 70 and 150 °C. Nuclear Magnetic Resonance (1H-NMR and HMBC) and Size Exclusion Chromatography (SEC) were used to characterize the polymers. The results indicate that the Sm(OAc)3 induces the polymerization of TMC to high conversion with number-average molecular weights of 3.11 × 103 to 38.40 × 103 Da. Based on the 1H-NMR end-group analysis of low-molecular-weight PTMC, it was proposed a coordination–insertion mechanism for the polymerization, with a breakdown of the acyl-oxygen bond of the TMC. In according to the kinetic study carried out, the polymerization rate is first-order with respect to monomer concentration with apparent rate constants of kap = 7.02 × 10−4 mol × L−1 × h−1. [ABSTRACT FROM AUTHOR]

To enhance the activity of the hydroxyl group of diosgenin, the diosgenyl derivative Dios–(CH2)6–OH with an alkyl spacer and end primary hydroxyl group was synthesised via the chain extension reaction between diosgenin and 1,6-hexanediol. Then the liquid crystal (LC) compounds Dios–(CH2)6–(trimethylene carbonate [TMC])n with different TMC content were obtained via the ring-opening polymerisation of TMC with Dios–(CH2)6–OH as initiator and mesogenic unit, importantly, there was no catalyst added. The chemical structures of the Dios–(CH2)6–OH and Dios–(CH2)6–(TMC)n were characterised by Fourier transform infrared (FT-IR) spectra and 1H NMR. The mesomorphism was characterised by polarising optical microscopy and X-ray diffraction measurement, and the phase transition was investigated by differential scanning calorimetry. The results showed that Dios–(CH2)6–(TMC)n displayed an enantiotropic smectic phase, and TMC content played an important role in the LC properties of Dios–(CH2)6–(TMC)n. The higher the TMC content, the lower the phase transition temperature of Dios–(CH2)6–(TMC)n. [ABSTRACT FROM AUTHOR]

Poly(trimethylene carbonate) (PTMC) derivatives have been extensively researched for use as low-toxicity biomaterials. Better biocompatibility and lower toxicity have been achieved by eliminating acid generation from the ester group at the side chains. In this study, thermosensitive PTMC derivatives bearing oligo(ethylene glycol) units are synthesized by ring-opening polymerization for the development of low-toxicity and thermosensitive soft materials. The viscoelastic properties of the obtained polymers are then investigated by rheometry to clarify the thermosensitive and molecular weight effects. Furthermore, thermosensitive behaviors and dynamics of these polymers are observed by UV-vis transmittance, DSC, and 1H NMR spectra analysis. These data suggest a mechanism for the thermosensitive behavior where it is surmised that some kind of dehydration phenomenon induces aggregation behavior in aqueous media above lower critical solution temperature. These thermosensitive behaviors provide an important road map for the development of thermosensitive soft materials using ester-free PTMC derivatives by controlling the thermosensitive behaviors and bulk properties. [ABSTRACT FROM AUTHOR]

Despite the increased expenditure of the pharmaceutical industry on research and development, the number of drugs for cardiovascular diseases that reaches the market is decreasing. A major issue is the limited ability of the current in vitro and experimental animal models to accurately mimic human heart disease, which hampers testing of the efficacy of potential cardiac drugs. Moreover, many non-heart-related drugs have severe adverse cardiac effects, which is a major cause of drugs’ retraction after approval. A main hurdle of current in vitro models is their inability to mimic the stiffness of in vivo cardiac tissue. For instance, poly(styrene) petri dishes, which are often used in these models, have a Young’s modulus in the order of GPa, while the stiffness of healthy human heart tissue is 100 kPa range. In this study, we focus on developing new membranes, with a set of properties for mimicry of cardiac tissue stiffness in vitro, based on methacrylate-functionalized macromers and triblock-copolymers of poly(trimethylene carbonate) and poly(ethylene glycol). The new membranes have Young’s moduli in the hydrated state ranging from 18 kPa (healthy tissue) to 2.5 MPa (pathological tissue), and are suitable for cell contraction studies using human pluripotent stem-cell-derived cardiomyocytes. The membranes with higher hydrophilicity have low drug adsorption and low Young’s moduli and could be suitable for drug screening applications.

The aim of this work was to fabricate microporous poly(trimethylene carbonate) (PTMC) vascular structures by stereolithography (SLA) for applications in tissue engineering and organ models. Leachable CaCO3 particles with an average size of 0.56 μm were used as porogens. Composites of photocrosslinkable PTMC and CaCO3 particles were cast on glass plates, crosslinked by ultraviolet light treatment and leached in watery HCl solutions. In order to obtain interconnected pore structures, the PTMC/CaCO3 composites had to contain at least 30 vol % CaCO3. Leached PTMC films had porosities ranging from 33% to 71% and a pore size of around 0.5 μm. The mechanical properties of the microporous PTMC films matched with those of natural blood vessels. Resins based on PTMC/CaCO3 composites with 45 vol % CaCO3 particles were formulated and successfully used to build vascular structures of various shapes and sizes by SLA. The intrinsic permeabilities of the microporous PTMC films and vascular structures were at least one order of magnitude higher than reported for the extracellular matrix, indicating no mass transfer limitations in the case of cell seeding.

Introduction: Poly(1,3-trimethylene carbonate) (PTMC) is a flexible amorphous polymer with good degradability and biocompatibility. The degradation of PTMC is critical for its application as a degradable polymer, more convenient and easy-to-control cross-linking strategies for preparing PTMC are required. Methods: The blends of poly(trimethylene carbonate) (PTMC) and cross-linked poly(ethylene glycol) diacrylate (PEGDA) were prepared by mixing photoactive PEGDA and PTMC and subsequently photopolymerizing the mixture with uv light. The physical properties and in vitro enzymatic degradation of the resultant PTMC/cross-linked PEGDA blends were investigated. Results: The results showed that the gel fraction of PTMC/cross-linked PEGDA blends increased while the swelling degree decreased with the content of PEGDA dosage. The results of in vitro enzymatic degradation confirmed that the degradation of PTMC/cross-linked PEGDA blends in the lipase solution occurred under the surface erosion mechanism, and the introduction of the uv cross-linked PEGDA significantly improved the resistance to lipase erosion of PTMC; the higher the cross-linking degree, the lower the mass loss. Discussion: The results indicated that the blends/cross-linking via PEGDA is a simple and effective strategy to tailor the degradation rate of PTMC., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Li, Lin, Wang, Lu, Sui, Ni, Guo, Jiang, Yang and Cui.)

Abstract: Electrolytes comprising poly(ethylene carbonate) (PEC)/poly(trimethylene carbonate) (PTM C) with lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) are prepared by a simple solvent casting method. Although PEC and PTMC have similar chemical structures, they are immiscible and two glass transitions are present in the differential scanning calorimetry (DSC) measurements. Interestingly, these two polymers change to miscible blends with the addition of LiTFSI, and the ionic conductivity increases with increasing lithium salt concentration. The optimum composition of the blend electrolyte is achieved at PEC6PTMC4, with a conductivity as high as 10−6 S cm−1 at 50 °C. This value is greater than that for single PEC‐ and PTMC‐based electrolytes. Moreover, the thermal stability of the blend‐based electrolytes is improved as compared to PEC‐based electrolytes. It is clear that the interaction between CO groups and Li+ gives rise to a compatible amorphous phase of PEC and PTMC. [ABSTRACT FROM AUTHOR]

The macroinitiator of poly(1,3‐trimethylene carbonate) (PTMC) with number‐average molecular weight ( M n ¯) of 9.6 × 103 g mol−1 was synthesized by ring‐opening polymerization at 120°C. Then, the novel terpolymer P(TMC‐b‐(LLA‐ran‐GA)) consisting of PTMC homopolymer segment attached with various monomer molar ratios of L‐lactide (LLA) and glycolide (GA) random copolymerization block was prepared with M n ¯ about 5.0 × 104 g mol−1 by ring‐opening polymerization in bulk at 140°C. The tailored molecular structures of P(TMC‐b‐(LLA‐ran‐GA)) were characterized by 1H nuclear magnetic resonance, 13C NMR, FTIR, and gel permeation chromatography, and chain microstructure analysis was performed in detail with 13C NMR spectroscopy. The effect of GA units on the thermal and crystallization behaviors, mechanical properties, as well as biodegradability of terpolymers was investigated by differential scanning calorimetry, wide‐angle X‐ray diffraction, stress‐strain measurements, and in vitro tests in comparison with corresponding poly(trimethylene carbonate‐block‐L‐lactide) copolymer P(TMC‐b‐LLA). The results show that amorphous PTMC segments have a significant effect on condensed state behavior of the terpolymers, and the incorporation of GA units strongly decreases the crystallinity and crystallization ability of LLA segment within terpolymers because of more random LLA‐GA sequence and shorter average LLA block length. Meanwhile, the toughness of materials is greatly improved, and in vitro degradation is also accelerated. Peripheral vascular stents were 3D printed for the first time and met the requirements for application. The results show totally biodegradable terpolymers with unique molecular structure, and modifiable properties are promising new biomaterials with advanced performance for biomedical application. [ABSTRACT FROM AUTHOR]

Designing calcium phosphate-loaded polymeric porous scaffolds with controlled architecture using stereolithography (SLA) has great potential in the field of bone tissue engineering. However, the use of poly(ester)s with suboptimal degradation property has mainly been reported. In the present work, we introduced a poly(trimethylene carbonate) (PTMC) and nano-hydroxyapatite (HA) resin suitable for SLA manufacturing and created cytocompatible 3D porous structure. First, the resin formulation and HA content were optimized for photo-crosslink-based SLA fabrication process. Subsequently, we evaluated the influence of the resin composition on physico-chemical characteristics of fabricated films and scaffolds. Then, the influence of the biomaterial composition on human bone marrow mesenchymal stem cell viability, adhesion and proliferation was assessed. Films and macroporous scaffolds were successfully produced by photo-crosslinking with up to 40 wt% of HA (relative to PTMC). We demonstrated that addition of HA in PTMC matrices induced a direct effect on the surface properties, in terms of wettability and topography. Additionally, mechanical tests revealed a correlation between the amounts of HA loaded in PTMC and the stiffness of the SLA-fabricated scaffolds. Importantly, the different photo-crosslinked biomaterials exhibited in vitro cytocompatibility, similar to tissue culture polystyrene. Those data suggest the possibility to fabricate highly tunable HA-loaded PTMC 3D porous structures for bone tissue engineering application. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The introduction of tissue engineering therapies for the repair of bone defects has been limited by poor survival of implanted cells. Because of the absence of a vascular network, the cells in a cell-scaffold construct are not adequately supplied with oxygen and nutrients. Thus far, all but one strategies to solve this problem have failed. Fortunately, oxygen-delivering biomaterials have shown promising results. In this study, composite microspheres comprising a poly(trimethylene carbonate) matrix and calcium peroxide particles (PTMC/CaO2) were prepared and assessed for their oxygen-delivering capacity and potential cytotoxicity. PTMC/CaO2 composite microspheres were shown to release oxygen for several weeks. Oxygen release appeared to be dependent on the presence of cholesterol esterase in the medium. The microspheres were not cytotoxic and promoted mesenchymal stromal cell proliferation under hypoxic conditions in vitro. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Vascular grafts with an inner diameter less than 6 mm are urgently needed due to the increasing prevalence of vascular disease. In this study, tubular scaffolds for vascular tissue engineering were fabricated by photo-crosslinking of acrylate-functionalized poly(trimethylene carbonate) (PTMC) macromers of different molecular weights in a glass mold. Porous structures were prepared by means of salt leaching. Tubular scaffolds were obtained with an inner diameter of 3 mm, a wall thickness of 1 mm, and a length of 4.5 cm. Pore sizes ranged from 0 to 290 µm, and the porosity was around 70%. The pores were homogeneously distributed and interconnected. PTMC macromers with a molecular weight of 4, 8, 13, 17, and 22 kg/mol were used. With increasing PTMC macromer molecular weight from 4 to 22 kg/mol, the E-modulus and maximum tensile strength of the scaffolds in the radial direction increased from 0.56 to 1.12 MPa and 0.12 to 0.55 MPa, respectively. Stress-strain curves for scaffolds made of 13, 17, and 22 kg/mol PTMC macromers showed a 'toe' region characteristic for native arteries, followed by a linear increase until the maximum stress was reached. The E-moduli of the latter scaffolds are comparable to those of native arteries, whereas the maximum tensile strengths are approximately fourfold lower. This can be improved, however, by cell seeding in the porous scaffolds and subsequent mechanical stimulation in a bioreactor. It is concluded that the porous tubular scaffolds made of 13, 17, and 22 kg/mol PTMC macromers are suitable scaffolds for vascular tissue engineering. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Main-chain biodegradable liquid crystal derived from cholesteryl derivative end-capped poly(trimethylene carbonate) was investigated. The novel liquid crystal was synthesised via ring-opening polymerisation of trimethylene carbonate initiated by cholesteryl derivative with an alkyl spacer and end primary hydroxyl group, without any catalyst. The chemical structure of resulting polymers was verified by1H NMR. Liquid crystalline properties were validated by X-ray diffraction, differential scanning calorimetry, and polarising optical microscopy. The results showed that all the synthesised polymers Chol-(CH2)2-(TMC)nexhibited mesomorphism in particular temperature ranges because of the introduction of the cholesteryl derivative moiety. [ABSTRACT FROM AUTHOR]

Fabrication of composite scaffolds using stereolithography (SLA) for bone tissue engineering has shown great promises. However, in order to trigger effective bone formation and implant integration, exogenous growth factors are commonly combined to scaffold materials. In this study, we fabricated biodegradable composite scaffolds using SLA and endowed them with osteopromotive properties in the absence of biologics. First we prepared photo-crosslinkable poly(trimethylene carbonate) (PTMC) resins containing 20 and 40 wt% of hydroxyapatite (HA) nanoparticles and fabricated scaffolds with controlled macro-architecture. Then, we conducted experiments to investigate how the incorporation of HA in photo-crosslinked PTMC matrices improved human bone marrow stem cells osteogenic differentiation in vitro and kinetic of bone healing in vivo . We observed that bone regeneration was significantly improved using composite scaffolds containing as low as 20 wt% of HA, along with difference in terms of osteogenesis and degree of implant osseointegration. Further investigations revealed that SLA process was responsible for the formation of a rich microscale layer of HA corralling scaffolds. To summarize, this work is of substantial importance as it shows how the fabrication of hierarchical biomaterials via surface-enrichment of functional HA nanoparticles in composite polymer stereolithographic structures could impact in vitro and in vivo osteogenesis. Statement of Significance This study reports for the first time the enhance osteopromotion of composite biomaterials, with controlled macro-architecture and microscale distribution of hydroxyapatite particles, manufactured by stereolithography. In this process, the hydroxyapatite particles are not only embedded into an erodible polymer matrix, as reported so far in the literature, but concentrated at the surface of the structures. This leads to robust in vivo bone formation at low concentration of hydroxyapatite. The reported 3D self-corralling composite architecture provides significant opportunities to develop functional biomaterials for bone repair and tissue engineering. [ABSTRACT FROM AUTHOR]

Purpose The use of ceramic materials in repair of bone defects is limited to non-load-bearing sites. We tested poly(trimethylene carbonate) (PTMC) combined with β-tricalcium phosphate or biphasic calcium phosphate particles for reconstruction of cranial defects. Materials and methods PTMC-calcium phosphate composite matrices were implanted in cranial defects in sheep for 3 and 9 months. Micro-computed tomography quantification and histological observation were performed for analysis. Results No differences were found in new bone formation among the defects left unfilled, filled with PTMC scaffolds, or filled with either kind of PTMC-calcium phosphate composite scaffolds. Porous β-TCP scaffolds as control led to a larger amount of newly formed bone in the defects than all other materials. Histology revealed abundant new bone formation in the defects filled with porous β-TCP scaffolds. New bone formation was limited in defects filled with PTMC scaffolds or different PTMC-calcium phosphate matrices. PTMC matrices were degraded uneventfully. New bone formation within the defects followed an orderly pattern. Conclusions PTMC did not interfere with bone regeneration in sheep cranial defects and is suitable as a polymer matrix for incorporating calcium phosphate particles. Increasing the content of calcium phosphate particles in the composite matrices may enhance the beneficial effects of the particles on new bone formation. [ABSTRACT FROM AUTHOR]

The present work reports the investigation of the biocompatibility, opsonisation and cell uptake by human primary macrophages and HepaRG cells of nanoparticles (NPs) formulated from poly(β-malic acid)- b -poly(β-hydroxybutyrate) (PMLA- b -PHB) and poly(β-malic acid)- b -poly(trimethylene carbonate) (PMLA- b -PTMC) diblock copolymers, namely PMLA 800 - b -PHB 7300 , PMLA 4500 - b -PHB 4400 , PMLA 2500 - b -PTMC 2800 and PMLA 4300 - b -PTMC 1400 . NPs derived from PMLA- b -PHB and PMLA- b -PTMC do not trigger lactate dehydrogenase release and do not activate the secretion of pro-inflammatory cytokines demonstrating the excellent biocompatibility of these copolymers derived nano-objects. Using a protein adsorption assay, we demonstrate that the binding of plasma proteins is very low for PMLA- b -PHB-based nano-objects, and higher for those prepared from PMLA- b -PTMC copolymers. Moreover, a more efficient uptake by macrophages and HepaRG cells is observed for NPs formulated from PMLA- b -PHB copolymers compared to that of PMLA- b -PTMC-based NPs. Interestingly, the uptake in HepaRG cells of NPs formulated from PMLA 800 - b -PHB 7300 is much higher than that of NPs based on PMLA 4500 - b -PHB 4400 . In addition, the cell internalization of PMLA 800 - b -PHB 7300 based-NPs, probably through endocytosis, is strongly increased by serum pre-coating in HepaRG cells but not in macrophages. Together, these data strongly suggest that the binding of a specific subset of plasmatic proteins onto the PMLA 800 - b -PHB 7300 -based NPs favors the HepaRG cell uptake while reducing that of macrophages. [ABSTRACT FROM AUTHOR]

Photo-crosslinked networks prepared from three-armed methacrylate functionalized PTMC oligomers (PTMC-tMA macromers) are attractive materials for developing an anatomically correct meniscus scaffold. In this study, we evaluated cell specific biocompatibility, in vitro and in vivo degradation behavior of, and tissue response to, such PTMC networks. By evaluating PTMC networks prepared from PTMC-tMA macromers of different molecular weights, we were able to assess the effect of macromer molecular weight on the degradation rate of the PTMC network obtained after photo-crosslinking. Three photo-crosslinked networks with different crosslinking densities were prepared using PTMC-tMA macromers with molecular weights 13.3, 17.8, and 26.7 kg/mol. Good cell biocompatibility was demonstrated in a proliferation assay with synovium derived cells. PTMC networks degraded slowly, but statistically significant, both in vitro as well as subcutaneously in rats. Networks prepared from macromers with higher molecular weights demonstrated increased degradation rates compared to networks prepared from initial macromers of lowest molecular weight. The degradation process took place via surface erosion. The PTMC networks showed good tissue tolerance during subcutaneous implantation, to which the tissue response was characterized by the presence of fibrous tissue and encapsulation of the implants. Concluding, we developed cell and tissue biocompatible, photo-crosslinked PTMC networks using PTMC-tMA macromers with relatively high molecular weights. These photo-crosslinked PTMC networks slowly degrade by a surface erosion process. Increasing the crosslinking density of these networks decreases the rate of surface degradation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2823-2832, 2016. [ABSTRACT FROM AUTHOR]

Recently, magnesium alloy vascular stents have aroused great attraction because of their biodegradability and good mechanical properties. However, the rapid degradation of magnesium alloy stents causes their premature collapse in clinical application. So far, there have been few magnesium alloy stent systems that achieved sufficient support time by using biodegradable coating. In this paper, a dual strengthened biodegradable coating on a AZ31b magnesium alloy stent was suggested to achieve stronger adhesion and lower water permeability. The composite coating consisted of a magnesium hydrate - magnesium fluoride (Mg(OH) 2 -MgF 2) inorganic base layer constructed by a simple two-step solution immersion and a graphene oxide - poly(trimethylene carbonate) outer layer prepared by ultrasonic spraying. The biodegradable composite coating modified magnesium alloy exhibited an extremely low corrosion current density of 4.3 × 10−10 A·cm−2, which is five orders of magnitude lower than the unmodified magnesium alloy. In vitro immersion tests revealed that the modification can effectively reduce the corrosion rate of the magnesium alloy stent, and the modified magnesium alloy stent can support at least 8 weeks. Furthermore, in vitro biological experiment revealed the modification of the composite coating improved the biocompatibility and ensured good microenvironment for vascular repair. These results suggest that the biodegradable composite coating has great potential for application in vascular stent. [Display omitted] • A dual strengthened anti-corrosion biodegradable coating was designed. • Water penetration and coating peeling were effectively inhibited after modification. • The modified Mg alloy exhibited superior corrosion resistance and biocompatibility. [ABSTRACT FROM AUTHOR]

Antimicromial and antioxidant bioactive films based on poly(lactic acid)/poly(trimenthylene carbonate) films incorporated with different concentrations of oregano essential oil (OEO) were prepared by solvent casting. The antimicrobial, antioxidant, physical, thermal, microstructural, and mechanical properties of the resulting films were examined. Scanning electron microscopy analysis revealed that the cross-section of films became rougher when OEO was incorporated into PLA/PTMC blends. Differential scanning calorimetry analysis indicated that crystallinity of PLA phase decreased by the addition of OEO, but this did not affect the thermal stability of the films. Water vapor permeability of films slightly increased with increasing concentration of OEO. However, active PLA/PTMC/OEO composite films showed adequate barrier properties for food packaging application. The antimicrobial and antioxidant capacities were significantly improved with the incorporation of OEO (p < 0.05). The results demonstrated that an optimal balance between the mechanical, barrier, thermal, antioxidant, and antimicrobial properties of the films was achieved by the incorporation of 9 wt % OEO into PLA/PTMC blends. [ABSTRACT FROM AUTHOR]

Poly(butylene succinate-co-adipate) (PBSA)/poly (trimethylene carbonate) (PTMC) blend samples with different weight ratios were prepared by solution blending. The morphologies after isothermal crystallization and in the melt were observed by optical microscopy (OM). Differential scanning calorimetry (DSC) was used to characterize the isothermal crystallization kinetics and melting behaviors. According to the OM image before and after melting, it was found that the blends formed heterogenous morphologies. When the PTMC content was low (20%), PBSA formed the continuous phase, while when the PTMC contents was high (40%), PBSA formed the dispersed phase. The glass transition temperatures (Tg) of the blends were determined by DSC and the differences of the Tgvalues were smaller than the difference between those of pure PBSA and PTMC. In addition, the equilibrium melting points were depressed in the blends. According to these results, the PBSA/PTMC blends were determined as being partially miscible blends. The crystallization kinetics was investigated according to the Avrami equation. It was found that the incorporation of PTMC did not change the crystallization mechanism of PBSA. However, the crystallization rate decreased with the increase of PTMC contents. The change of crystallization kinetics is related with the existences of amorphous PTMC, the partial miscibility between PLLA and PTMC, and the changes of phase structures. [ABSTRACT FROM PUBLISHER]

The degradation of the poly(trimethylene carbonate) (PTMC) and poly(trimethylene carbonate-co-ε-caprolactone) (P(TMC-co-CL)) networks cross-linked by 0.01 and 0.02 mol % 2,21-bis(trimethylene carbonate-5-yl)-butylether (BTB) was carried out in the conditions of hydrolysis and enzymes in vitro and subcutaneous implantation in vivo. The results showed that the cross-linked PTMC networks exhibited much faster degradation in enzymatic conditions in vitro and in vivo versus in a hydrolysis case due to the catalyst effect of enzymes; the weight loss and physical properties of the degraded networks were dependent on the BTB amount. The morphology observation in lipase and in vivo illustrated that enzymes played an important role in the surface erosion of cross-linked PTMC. The hydrolytic degradation rate of the cross-linked P(TMC-co-CL) networks increased with increasing ε-caprolactone (CL) content in composition due to the preferential cleavage of ester bonds. Cross-linking is an effective strategy to lower the degradation rate and enhance the form-stability of PTMC-based materials. [ABSTRACT FROM AUTHOR]

Objectives Our study compared two novel, biodegradable poly(trimethylene carbonate) ( PTMC) barrier membranes to clinically applied barrier membranes in maintaining volume of block autologous bone grafts in a rat mandible model. Material and methods Two hundred and forty rats were included in this study. Block autologous bone grafts of 5 mm in diameter were harvested from the mandibular angles and transplanted onto the contralateral side. The bone grafts were either covered with a membrane or left uncovered. The applied membranes included pure PTMC membranes, biphasic calcium phosphate ( BCP) incorporated PTMC composite membranes, expanded poly(tetrafluoroethylene) (e- PTFE) membranes (Tex) and collagen membranes (Geistlich Bio-Gide). After 2, 4 and 12 weeks, the rat mandibles were retrieved and analysed by histological evaluation and μCT quantification. Results The histological evaluation revealed that in time the block autologous bone graft was well integrated to the recipient bone via gradually maturing newly formed bone and did not show signs of resorption, independent of membrane coverage or types of membrane. μCT quantification showed the volume of the bone graft and recipient bone together was maintained by new bone formation and recipient bone resorption. Conclusions Our study showed that the use of PTMC membranes and PTMC-BCP composite membranes resulted in similar bone remodelling to the collagen membranes and e- PTFE membranes and that the use of barrier membranes did not interfere with bone remodelling of the bone grafts and recipient bones. However, the used barrier membranes seemed not to contribute in maintaining the volume of block autologous bone grafts. [ABSTRACT FROM AUTHOR]

The degradation of poly(trimethylene carbonate) (PTMC) implants with different molecular weights was investigated in vitro and in vivo . The results showed that PTMC degraded in vitro enzymolysis case and in vivo via surface erosion. The effect of the molecular weight on the degradation rate of PTMC was investigated in light of hydrophilicity and form-stability. A higher degradation rate was seen in the high molecular weight PTMC and its more hydrophobic surface with better form-stability. Furthermore, PTMC had a higher degradation rate of in vitro enzymolysis because of the surfactants role of lipase in diffusion of the degradation products. The results indicate that the form-stabilized PTMC is a promising candidate for clinical subcutaneous implants especially due to their tunable degradation rate. [ABSTRACT FROM AUTHOR]

BACKGROUND: Advances in rapid-prototyping and 3D printing technologies have enhanced the possibilities in preparing designed architectures for tissue engineering applications. Amajor advantage in custom designing is the ability to create structures with desired mechanical properties. While the behaviour of a designed scaffold can be simulated using bulk material properties, it is important to verify the behaviour of a printed scaffold at the microstructure level. OBJECTIVE: In this study we present an effective method in validating the mechanical behaviour of designed scaffolds using a μCT with an in-situ mechanical deformation device. METHODS: The scaffolds were prepared from biodegradable poly(trimethylene carbonate) (PTMC) by stereolithography and images obtained using a high-resolution μCT with 12.25 μm isometric voxels. The data was processed (filtering, segmentation) and analysed (surface generation, registration) to extract relevant deformation features. RESULTS: The computed local deformation fields, calculated at sub-pore resolutions, displayed expected linear behaviour within the scaffold along the compressions axis. On planes perpendicular to this axis, the deformations varied by 150-200 μm. CONCLUSIONS: μCT based imaging with in-situ deformation provides a vital tool in validating the design parameters of printed scaffolds. Deformation fields obtained from micro-tomographic image volumes can serve to corroborate the simulated ideal design with the realized product. [ABSTRACT FROM AUTHOR]