Figure 1 : Partially physically crosslinked gelatin achieves high-fidelity printing of scaffolds with ideal tissue engineering properties.

From: A bioprosthetic ovary created using 3D printed microporous scaffolds restores ovarian function in sterilized mice

Figure 1

(a) Photograph of macroscopic view of gelatin 3D printed with 100 μm nozzle, five-layered scaffold. Each layer is discrete and scaffold struts are smooth and continuous leading to a homogeneous pore distribution. Inset: Magnification of scaffold porosity, scale bar 250 μm. (b) Gelation profile of 10%. (w/v) gelatin solution. Sol-gel transition occurs at 33 °C when G′G″. Gelatin was maintained at 30 °C (dashed line) for 3D printing to maintain gelatin in a partially crosslinked state as evident by the fact that the storage modulus of gelatin (30 °C G′ 36 Pa) increased nearly two orders of magnitude upon further cooling (17 °C G′ 5,400 Pa). (c) Response of 30 °C gelatin to increasing strain. Up to 50% strain, the gel exhibited a linear response to strain and after 50% strain, the gel exhibited strain-hardening until the point of catastrophic failure (the critical point), maximum G′ (critical G′ 45 Pa, critical strain 518%, critical stress 233 Pa). (d) Summary of rheological properties comparing ideal printable (30 °C) gel to robust, more heavily crosslinked and non-ideal gel (25 °C). Ideal, printable gels have lower G′, critical G′ (G′c), and critical stress (γc) and higher critical stains (σc). (e) Schematic of the thermoreversible properties of gelatin. Above 33 °C, gelatin is a solution in which polypeptide chains are separate and soluble. Below 33 °C, local regions of triple helices begin to form and physical crosslink polypeptide chains come together to form the gel. As temperature progressively lowers, more and more crosslinks occur until a fully crosslinked gel forms at 17 °C.