Toughness enhancers for bone scaffold materials based on biocompatible photopolymers

Abstract

Providing access to the benefits of additive manufacturing technologies in tissue engineering, vinyl esters recently came into view as appropriate replacements for (meth)acrylates as precursors for photopolymers. Their low cytotoxicity and good biocompatibility as well as favorable degradation behavior are their main assets. Suffering from rather poor mechanical properties, particularly in terms of toughness, several improvements have been made over the last years. Especially, thiol–ene chemistry has been investigated to overcome those shortcomings. In this study, we focused on additional means to further improve the toughness of an already established biocompatible vinyl ester‐thiol formulation, eligible for digital light processing‐based stereolithography. All molecules were based on poly(ε‐caprolactone) as building block and the formulations were tested regarding their reactivity and the resulting mechanical properties. They all performed well as toughness enhancer, ultimately doubling the impact resistance of the reference system. © 2018 The Authors. Journal of Polymer Science Part A: Polymer Chemistry published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 110–119

Novel synthesis routes for the preparation of low toxic vinyl ester and vinyl carbonate monomers

“…[5][6][7][8][9][10] Most recently, this class of polymers has been used in highly developed fields of medicinal chemistry, and it will enhance the future of 3 D printing in the field of tissue engineering. [38] Experimental part 1 H-NMR-and 13 C-NMR-spectra were measured either on a BRUKER Avance DRX-400 FTNMR spectrometer at 400 MHz for 1 H-NMR and at 100 MHz for 13 C-NMR or on a BRUKER AC-E-200 FTNMR spectrometer at 200 MHz for 1 H-NMR and 50 MHz for 13 C-NMR. Chemical shifts (d) are reported in ppm (s ¼ singulett, d ¼ duplet, t ¼ triplett, q ¼ quartett, quint ¼ quintet, m ¼ multiplet) and coupling constants (J) in Hz.…”

Exploring the limits of toughness enhancers for 3D printed photopolymers as bone replacement materials

“…The addition of high molecular weight additives in combination with thiols as CTAs results in reduced but more homogeneous network density and further decrease of shrinkage stress during photopolymerization 25,26 . There are already established photopolymerizable vinyl ester‐based thiol‐ene networks used in bone grafts substitutes fabricated via DLP‐SLA 27 . Here, the trifunctional thiol trimethylolpropane tris(3‐mercaptopropionate) (Thiol 1) and the high molecular weight, linear polymer poly(ε‐caprolactone) (PCL) were used.…”

“…PCL is already used as implant material in biomedical applications, 28 because it shows high biocompatibility and biodegradability, and supports cell growth 29 . These thiol‐ene systems were improved, having a more regulated network structure compared to homopolymerized DVA 20,27 . Physical interactions of PCL as non‐reactive additive led to improved mechanical properties, but more importantly, the introduction of polymerizable motifs into the toughness enhancers and thus their incorporation into the final polymer network led to even better performance 27 .…”

Increasing the Microfabrication Performance of Synthetic Hydrogel Precursors through Molecular Design

“…Although this advanced 3D printing technology offers exciting opportunities for the field of tissue engineering, its main limitation is the limited number of commercially available resins for creating suitable biomaterials for tissue engineering purposes . The most commonly used resins involve low-molar-mass acrylic monomers and epoxies, which lead to highly cross-linked, nondegradable, rigid, and brittle structures that are not suitable to serve tissue engineering applications. , Conversely, hydrogel precursors form soft and flexible networks upon cross-linking. In particular, chemically cross-linked synthetic hydrogels have become attractive alternatives for tissue engineering applications owing to their biocompatibility, tailorable design, low cost, and reproducible production routes. , In contrast to nature-derived polymers, synthetic polymers offer tunable physical properties and are compatible with various scaffold manufacturing technologies exploiting mild conditions .…”