Abstract: A 3D structure of a hydrogel for supporting cell growth or for use in sustained drug delivery is formed using peptides and/or peptide derivatives that self-assemble via cross-linking into a stiff gel. The hydrogel structure is formed using a method based on 3D printing. A hydrogel precursor is extruded under conditions to generate a hydrogel, by extruding a solution of the peptides into a solution containing cations, whereby the cations enable cross-linking of pi-stacked peptides, or by co-extruding it with the cations, the peptides and cations being mixed only at the point of co-extrusion. The stiffness of the hydrogel can be tuned by adjusting the combination of peptides, either by the selection of peptides or combinations thereof, or the proportions of the combinations, and/or by adjusting the proportion of cations present.

Abstract: A method and apparatus for controlling a stream of liquid and air segments wherein the liquid and air segments are selectively aspirated into a first fluid conduit in a plurality of cycles, each cycle beginning with the aspiration of a first air segment and ending with the aspiration of a final air segment. The liquid and air segments are then transferred from the first fluid conduit to a second fluid conduit. The volume of the final air segment of each cycle is then adjusted after the final air segment has moved into the second fluid conduit. Next, the liquid segments and the air segments of each cycle are transferred from the second fluid conduit to a third fluid conduit. The volume of the first air segment of each cycle is then adjusted after the first air segment has moved into the third fluid conduit.

Abstract: A method and apparatus for controlling a stream of liquid and air segments wherein the liquid and air segments are selectively aspirated into a first fluid conduit in a plurality of cycles, each cycle beginning with the aspiration of a first air segment and ending with the aspiration of a final air segment. The liquid and air segments are then transferred from the first fluid conduit to a second fluid conduit. The volume of the final air segment of each cycle is then adjusted after the final air segment has moved into the second fluid conduit. Next, the liquid segments and the air segments of each cycle are transferred from the second fluid conduit to a third fluid conduit. The volume of the first air segment of each cycle is then adjusted after the first air segment has moved into the third fluid conduit.

Abstract: A method and apparatus for controlling a stream of liquid and air segments wherein the liquid and air segments are selectively aspirated into a first fluid conduit in a plurality of cycles, each cycle beginning with the aspiration of a first air segment and ending with the aspiration of a final air segment. The liquid and air segments are then transferred from the first fluid conduit to a second fluid conduit. The volume of the final air segment of each cycle is then adjusted after the final air segment has moved into the second fluid conduit. Next, the liquid segments and the air segments of each cycle are transferred from the second fluid conduit to a third fluid conduit. The volume of the first air segment of each cycle is then adjusted after the first air segment has moved into the third fluid conduit.