PMC

(A) Inter-thick filament spacing values for Dextran T-500 and T-10 were calculated from linear fits () to x-ray diffraction measurements () and plotted against osmotic pressure. (B) Reductions in thick filament radius with increased osmotic pressure were calculated from the fractional changes in inter-thick filament spacing with Dextran T-500, using an 8 nm in vivo thick filament radius () and a fixed thin filament radius of 4 nm (). (C) The relationship between thick-to-thin filament surface distance and osmotic pressure was calculated () from the values in panels A and B. The effects of osmotic stress on a pair of thin (solid) and thick (hollow) filaments are illustrated for 6% T-500 (lower), 0% Dextran (middle), and 0.78% T-10 (upper), with thick filament radius and thick-to-thin filament surface distance listed in nm. Dashed boxes outline myofilament lattice space, where Dextran T-10 diffuses into the lattice to reduce thick filament radii without significantly affecting lattice spacing and from which Dextran T-500 is excluded to simultaneously compress thick filament radii and inter-thick filament lattice spacing. Vertical dashed lines across panel highlight the centered-alignment of thin filaments and shifted alignment of thick-filaments.

Example of INMJ. (a) Cross-section of a co-axial nozzle assembly model. (b) Schematic of the fabrication of the hollow filament (c) photography of a printed alginate hollow filaments (left) and inverted microscopic image of the hollow filaments (top right). Perfusion of the filament with cell culture media (bottom right). Reprinted from Coaxial nozzle-assisted 3D bioprinting with built-in microchannels for nutrients delivery, showing a co-axial needle allowing to print hollow filament using a core–shell concept. Gao et al. Copyright (2015), with permission from Elsevier [].

Representative SEM images of (A) the outer and (B) inner surfaces of the hollow CaP filament.

HF spinning: (a) TOCNF hydrogel and air extrusion in a coaxial setup. (b) Photograph of a long hollow filament formed from the extruded TOCNF hydrogel on the coagulation bath. (c) Schematic illustration of the drying process used for small, medium (maximum tension), as well as large size (moderate tension) hollow filaments. (d) Photograph of dry hollow filaments.