Microwave-assisted facile fabrication of porous poly (glycerol sebacate) scaffolds

Different methods of synthesizing poly(glycerol sebacate) (PGS): A review

Poly(glycerol sebacate) (PGS) is a biodegradable elastomer that has attracted increasing attention as a potential material for applications in biological tissue engineering. The conventional method of synthesis, first described in 2002, is based on the polycondensation of glycerol and sebacic acid, but it is a time-consuming and energy-intensive process. In recent years, new approaches for producing PGS, PGS blends, and PGS copolymers have been reported to not only reduce the time and energy required to obtain the final material but also to adjust the properties and processability of the PGS-based materials based on the desired applications. This review compiles more than 20 years of PGS synthesis reports, reported inconsistencies, and proposed alternatives to more rapidly produce PGS polymer structures or PGS derivatives with tailor-made properties. Synthesis conditions such as temperature, reaction time, reagent ratio, atmosphere, catalysts, microwave-assisted synthesis, and PGS modifications (urethane and acrylate groups, blends, and copolymers) were revisited to present and discuss the diverse alternatives to produce and adapt PGS.

Solvent-Free Production by Extrusion of Bio-Based Poly(glycerol-co-diacids) Sheets for the Development of Biocompatible and Electroconductive Elastomer Composites

Faced with growing global demand for new potent, bio-based, biocompatible elastomers, the present study reports the solvent-free production of 13 pure and derived poly(glycerol-co-diacid) composite sheets exclusively using itaconic acid, sebacic acid, and 2,5-furandicarboxylic acid (FDCA) with glycerol. Herein, modified melt polycondensation and Co(II)-catalyzed polytransesterification were employed to produce all exploitable prepolymers, enabling the easy and rapid manufacturing of elastomer sheets by extrusion. Most of our samples were loaded with 4 wt% of various additives such as natural polysaccharides, synthetic polymers, and/or 25 wt% sodium chloride as porogen agents. The removal of unreacted monomers and acidic short oligomers was carried out by means of washing with NaHCO3 aqueous solution, and pH monitoring was conducted until efficient sheet surface neutralization. For each sheet, their surface morphologies were observed by Field-emission microscopy, and DSC was used to confirm their amorphous nature and the impact of the introduction of every additive. The chemical constitution of the materials was monitored by FTIR. Then, cytotoxicity tests were performed for six of our most promising candidates. Finally, we achieved the production of two different types of extrusion-made PGS elastomers loaded with 10 wt% PANI particulates and 4 wt% microcrystalline cellulose for adding potential electroconductivity and stability to the material, respectively. In a preliminary experiment, we showed the effectiveness of these materials as performant, time-dependent electric pH sensors when immersed in a persistent HCl atmosphere.

Surface channel patterned and endothelialized poly(glycerol sebacate) based elastomers

Prevascularization of tissue equivalents is critical for fulfilling the need for sufficient vascular organization for nutrient and gas transport. Hence, endothelial cell culture on biomaterials is of great importance for researchers. Numerous alternate strategies have been suggested in this sense, with cell-based methods being the most commonly employed. In this study, poly (glycerol sebacate) (PGS) elastomers with varying crosslinking ratios were synthesized and their surfaces were patterned with channels by using laser ablation technique. In order to determine an ideal material for cell culture studies, the elastomers were subsequently mechanically, chemically, and biologically characterized. Following that, human umbilical vein endothelial cells (HUVECs) were seeded into the channels established on the PGS membranes and cultured under various culture conditions to establish the optimal culture parameters. Lastly, the endothelial cell responses to the synthesized PGS elastomers were evaluated. Remarkable cell proliferation and impressive cellular organizations were noticed on the constructs created as part of the investigation. On the concrete output of this research, arrangements in various geometries can be created by laser ablation method and the effects of various molecules, drugs or agents on endothelial cells can be evaluated. The platforms produced can be employed as an intermediate biomaterial layer containing endothelial cells for vascularization of tissue-engineered structures, particularly in layer-by-layer tissue engineering approaches.

A Bilayered, Electrospun Poly(Glycerol-Sebacate)/Polyurethane-Polyurethane Scaffold for Engineering of Endothelial Basement Membrane

In the cardiovascular system, heart valves and vessels are subjected to continuous cyclic mechanical loadings due to the pulsatile nature of blood flow. Hence, in leveraging tissue engineering (TE) strategies to regenerate such a system, the candidate scaffold should not only be biocompatible with the desired biodegradation rate, but it should also be mechanically competent to provide a supportive structure for facilitating stem cells retention, growth, and differentiation. To this end, herein, we introduced a novel scaffold composed of poly(glycerol-sebacate) (PGS) and polyurethane (PU), which comprises of two layers: an electrospun pure PU layer beneath another electrospun PGS/PU layer with a different ratio of PGS to PU (3:2, 1:1, 2:3 Wt:Wt). The electrospun PGS/PU-PU scaffold was mechanically competent and showed intended hydrophilicity and a good biodegradation rate. Moreover, the PGS/PU-PU scaffold indicated cell viability and proliferation within ten days of in vitro cell culture and upon 7 day vascular endothelial growth factor (VEGF) stimulation, supported endothelial differentiation of mesenchymal stem cells by significant overexpression of platelet-endothelial cell adhesion molecule-1, von Willebrand factor, and VEGF receptor 2. The results of this study could be implemented in cardiovascular TE strategies when regeneration of blood vessel or heart valve is desired.

Poly(Glycerol Sebacate) in Biomedical Applications-A Review of the Recent Literature

Poly(glycerol sebacate) (PGS) continues to attract attention for biomedical applications owing to its favorable combination of properties. Conventionally polymerized by a two-step polycondensation of glycerol and sebacic acid, variations of synthesis parameters, reactant concentrations or by specific chemical modifications, PGS materials can be obtained exhibiting a wide range of physicochemical, mechanical, and morphological properties for a variety of applications. PGS has been extensively used in tissue engineering (TE) of cardiovascular, nerve, cartilage, bone and corneal tissues. Applications of PGS based materials in drug delivery systems and wound healing are also well documented. Research and development in the field of PGS continue to progress, involving mainly the synthesis of modified structures using copolymers, hybrid, and composite materials. Moreover, the production of self-healing and electroactive materials has been introduced recently. After almost 20 years of research on PGS, previous publications have outlined its synthesis, modification, properties, and biomedical applications, however, a review paper covering the most recent developments in the field is lacking. The present review thus covers comprehensively literature of the last five years on PGS-based biomaterials and devices focusing on advanced modifications of PGS for applications in medicine and highlighting notable advances of PGS based systems in TE and drug delivery.

Polyglycerol Hyperbranched Polyesters: Synthesis, Properties and Pharmaceutical and Biomedical Applications

In a century when environmental pollution is a major issue, polymers issued from bio-based monomers have gained important interest, as they are expected to be environment-friendly, and biocompatible, with non-toxic degradation products. In parallel, hyperbranched polymers have emerged as an easily accessible alternative to dendrimers with numerous potential applications. Glycerol (Gly) is a natural, low-cost, trifunctional monomer, with a production expected to grow significantly, and thus an excellent candidate for the synthesis of hyperbranched polyesters for pharmaceutical and biomedical applications. In the present article, we review the synthesis, properties, and applications of glycerol polyesters of aliphatic dicarboxylic acids (from succinic to sebacic acids) as well as the copolymers of glycerol or hyperbranched polyglycerol with poly(lactic acid) and poly(ε-caprolactone). Emphasis was given to summarize the synthetic procedures (monomer molar ratio, used catalysts, temperatures, etc.,) and their effect on the molecular weight, solubility, and thermal and mechanical properties of the prepared hyperbranched polymers. Their applications in pharmaceutical technology as drug carries and in biomedical applications focusing on regenerative medicine are highlighted.

Multiphoton Imaging of Collagen, Elastin, and Calcification in Intact Soft-Tissue Samples

Multiphoton-induced second-harmonic generation and two-photon excitation enable imaging of collagen and elastin fibers at micron-level resolution to depths of hundreds of microns, without the use of exogenous stains. These attributes can be leveraged for quantitative analysis of the 3D architecture of collagen and elastin fibers within intact, soft tissue specimens such as the artery and bladder wall. This architecture influences the function of intramural cells and also plays a primary role in determining tissue passive mechanical properties. Calcification deposition in soft tissues is a highly prevalent pathology in both older and diseased populations that can alter tissue properties. In this unit, we provide a protocol for simultaneous multiphoton microscopy (MPM) imaging and analysis of 3D collagen and elastin structures with calcification, which is effective for fixed and fresh intact samples. We also provide an associated micro-CT protocol to identify regions of interest in the samples as a means to target the MPM imaging. © 2018 by John Wiley & Sons, Inc.