Polylactide Block Copolymers using Trimethylene Carbonate with Methoxyethoxy Side Groups for Dual Modification of Hydrophilicity and Biodegradability: Polylactide Block Copolymers using Trimethylene Carbonate with Methoxyethoxy …

Understanding the hydrolysis mechanism on segments and aggregate structures: Corrosion-tailored poly (lactic acid) deriving copolymers with δ-valerolactone

Poly (L-lactic acid) (PLLA) based copolymers modified with δ-valerolactone (DVL) through random copolymerization (PVLA-R) and block copolymerization (PVLA-B) with various DVL content were prepared to investigate their degradation regulation and mechanism. Chemical structure, thermal properties, hydrophilicity, crystallization as well as the crystal defects of the obtained copolymers were respectively confirmed. Degradation regulation of both PVLA-R and PVLA-B, such molecular weight and pH value changes of PLLA based copolymers were investigated via vitro degradation method. In order to further explore the degradation principle of the two copolymers, their degradation residues at different stages were systematically studied. The addition and increasing content of DVL disturbs the regularity of original PLLA molecular structure, resulting in accelerating degradation of copolymers. Compared with amorphous region, the crystalline region of both two copolymers has better corrosion resistance, which could be confirmed by increased melting point and crystallinity of both PVLA-R and PVLA-B degradation residues. PVLA-B copolymers show relatively superior degradation resistance mainly due to their higher molecular weight, crystallinity and hydrophobic index than PVLA-R copolymers.

(Bio)manufactured Solutions for Treatment of Bone Defects with Emphasis on US-FDA Regulatory Science Perspective

Bone defects, with second highest demand for surgeries around the globe, may lead to serious health issues and negatively influence patient lives. The advances in biomedical engineering and sciences have led to the development of several creative solutions for bone defect treatment. This review provides a brief summary of bone graft materials, an organized overview of top-down and bottom-up (bio)manufacturing approaches, plus a critical comparison between advantages and limitations of each method. We specifically discuss additive manufacturing techniques and their operation mechanisms in detail. Next, we review the hybrid methods and promising future directions for bone grafting, while giving a comprehensive US-FDA regulatory science perspective, biocompatibility concepts and assessments, and clinical considerations to translate a technology from a research laboratory to the market. The topics covered in this review could potentially fuel future research efforts in bone tissue engineering, and perhaps could also provide novel insights for other tissue engineering applications.

Biodegradable waterborne polyurethane grafted with gelatin hydrolysate via solvent-free copolymerization for potential porous scaffold material

One potential porous scaffold material based on polyester waterborne polyurethane (PEUR) grafted with modified gelatin hydrolysate (GH) has been investigated in this research. First, the GH was modified with a silane coupling agent (KH550), and then the modified GH was mixed with pre-polymer emulsion of PEUR to obtain the PEUR grafted GH emulsion (PEUR-g-GH). The synthesized PEUR-g-GH emulsions were characterized by stability analysis and viscosity test. Moreover, the film-forming property of PEUR-g-GH has also been studied, and the PEUR-g-GH films were characterized regarding the water resistance, solvent resistance, mechanical properties, FTIR, AFM, SEM, DMA, TGA and contact angle testing. Finally, the bioactivity and biodegradation were investigated by soaking PEUR-g-GH scaffolds in simulated body fluid (SBF). The results indicated that the PEUR-g-GH emulsion has good stability, water resisting (the contact angle was over 90^o), the PEUR-g-GH showed excellent film-forming, high storage modulus, good structural homogeneity and thermal stability (the temperature of maximum weight loss was over 350 °C). The freeze-dried sample showed porous structure, and the mutual crosslinking of layers can contribute to a good bearing capacity for scaffold. The SBF biodegradability revealed that the biodegradation rate and degree of films gradually increased with the content of GH increased. In addition, the cells on the material were markedly enhanced, and most of cells have proliferated and formed vesicles, which shown a good biocompatibility.

Enhanced bone regeneration composite scaffolds of PLLA/β-TCP matrix grafted with gelatin and HAp

The composite polylactide PLLA/β-TCP scaffolds were fabricated by solution casting and were coated with gelatin/hydroxyapatite (Gel/HAp) to improve the biological properties of the composite scaffolds. The Gel/HAp mixture was prepared using an in situ reaction, and a grafting-coating method was used to increase the efficiency of coating the PLLA/β-TCP matrix with Gel/HAp. First, free amino groups were introduced by 1,6-hexanediamine to aminolyze the PLLA/β-TCP matrix surface. Second, glutaraldehyde was coupled to Gel/HAp as a crosslinking agent. The structure and properties of Gel/HAp-modified PLLA/β-TCP films were characterized by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and water contact angle measurements (WCA). The experimental results show that 23 wt% HAp was uniformly dispersed in the gelatin coating by in situ synthesis. The Gel/HAp composite coating was successfully immobilized on the aminolyzed PLLA/β-TCP surface via a chemical grafting method, which promoted a lower degradation rate and was more hydrophilic than a physical grafting method. The Gel/HAp composite coating adhered tightly and homogeneously to the hydrophobic PLLA/β-TCP surface. Moreover, mouse embryo osteoblast precursor (MC3T3-E1) cells grown on the scaffolds were behaviorally and morphologically characterized. The results indicated that the Gel/HAp composite coating was favorable for the attachment and proliferation of preosteoblasts and that Gel/HAp-NH-PLLA/β-TCP would be a candidate scaffold for bone repair.

Monoether-Tagged Biodegradable Polycarbonate Preventing Platelet Adhesion and Demonstrating Vascular Cell Adhesion: A Promising Material for Resorbable Vascular Grafts and Stents

We developed a biodegradable polycarbonate that demonstrates antithrombogenicity and vascular cell adhesion via organocatalytic ring-opening polymerization of a trimethylene carbonate (TMC) analogue bearing a methoxy group. The monoether-tagged polycarbonate demonstrates a platelet adhesion property that is 93 and 89% lower than those of poly(ethylene terephthalate) and polyTMC, respectively. In contrast, vascular cell adhesion properties of the polycarbonate are comparable to those controls, indicating a potential for selective cell adhesion properties. This difference in the cell adhesion property is well associated with surface hydration, which affects protein adsorption and denaturation. Fibrinogen is slightly denatured on the monoether-tagged polycarbonate, whereas fibronectin is highly activated to expose the RGD motif for favorable vascular cell adhesion. The surface hydration, mainly induced by the methoxy side chain, also contributes to slowing the enzymatic degradation. Consequently, the polycarbonate exhibits decent blood compatibility, vascular cell adhesion properties, and biodegradability, which is promising for applications in resorbable vascular grafts and stents.

Poly(trimethylene carbonate)-based polymers engineered for biodegradable functional biomaterials

This review presents recent examples of applications and functionalization strategies of poly(trimethylene carbonate), its copolymers, and its derivatives to exploit the unique physicochemical properties of the aliphatic polycarbonate backbone.

Poly(lactide-co-trimethylene carbonate) and polylactide/polytrimethylene carbonate blown films

In this work, poly(lactide-co-trimethylene carbonate) and polylactide/polytrimethylene carbonate films are prepared using a film blowing method. The process parameters, including temperature and screw speed, are studied, and the structures and properties of the P(LA-TMC) and PLA/PTMC films are investigated. The scanning electron microscope (SEM) images show that upon improving the content of TMC and PTMC, the lamellar structures of the films are obviously changed. With increasing TMC monomer or PTMC contents, the elongation at the break is improved, and the maximum is up to 525%. The water vapor permeability (WVP) results demonstrate that the WVP of the PLA/PTMC film increased with the increase in the PTMC content, whereas the WVP of the P(LA-TMC) film decreased. Thermogravimetric (TG) measurements reveal that the decomposition temperatures of the P(LA-TMC) and PLA/PTMC films decrease with increases in the TMC and PTMC contents, respectively, but the processing temperature is significantly lower than the initial decomposition temperature. P(LA-TMC) or PLA/PTMC film can extend the shelf life of apples, for instance, like commercial LDPE film used in fruit packaging in supermarkets.