Processing variables of direct-write, near-field electrospinning impact size and morphology of gelatin fibers

Abstract

Several biofabrication methods are being investigated to produce scaffolds that can replicate the structure of the extracellular matrix. Direct-write, near-field electrospinning of polymer solutions and electrowriting of polymer melts are methods which combine fine fiber formation with computer-guided control. Research with such systems has focused primarily on synthetic polymers. To better understand the behavior of biopolymers used for direct-writing, this project investigated changes in fiber morphology, size, and variability caused by varying gelatin and acetic acid concentration, as well as process parameters such as needle gauge and height, stage speed, and interfiber spacing. Increasing gelatin concentration at a constant acetic acid concentration improved fiber morphology from large, planar structures to small, linear fibers with a median of 2.3 µm. Further varying the acetic acid concentration at a constant gelatin concentration did not alter fiber morphology and diameter throughout the range tested. Varying needle gauge and height further improved the median fiber diameter to below 2 µm and variability of the first and third quartiles to within ±1 µm of the median. Additional adjustment of stage speed did not impact the fiber morphology or diameter. Repeatable interfiber spacings down to 250 µm were shown to be capable with the system. In summary, this study illustrates the optimization of processing parameters for direct-writing of gelatin to produce fibers on the scale of collagen fibers. This system is thus capable of replicating the fibrous structure of musculoskeletal tissues with biologically relevant materials which will provide a durable platform for the analysis of single cell-fiber interactions to help better understand the impact scaffold materials and dimensions have on cell behavior.

Double crosslinked biomimetic composite hydrogels containing topographical cues and WAY-316606 induce neural tissue regeneration and functional recovery after spinal cord injury

“…1 shows the schematic of making PCL microfiber-reinforced WAY-316606 composite hydrogel scaffold and implantation of the composite hydrogel scaffolds into the SCI tissue defects. Near-field direct writing electrospinning technology has gained attention in the fields of biology and tissue engineering and has been widely used in tissue engineering scaffolds [ [22] , [23] , [24] ]. Through the near-field direct writing electrospinning technology, the diameter of the electrospun fibers and the gap between the spinning fibers can be controlled, and they can be stacked layer by layer [ [25] , [26] , [27] ].…”

Rapid Magnetically Directed Assembly of Pre‐Patterned Capillary‐Scale Microvessels

“…FEP involves the translation of a collection surface and resulting mechanical forces to pull polymeric microfibers from solution onto a rotating mandrel; electric fields are solely utilized to re-establish contact between the depositing microfiber and collection substrate should microfiber deposition be transiently disrupted. [24][25][26][27][28][29] In contrast, SEW combines 3D printing with electrospinning at short spinneret to collector distances, such that electrostatic forces drive the formation and controlled deposition of polymeric microfibers onto an oppositely charged collection surface. [22,23] We sought to control the diameters of microfibers produced using both methods by tuning the concentration and resulting viscosity of PCL solutions.…”

“…At the crux of our approach is a sacrificial capillarytemplating polycaprolactone (PCL) microfiber lattice that can be fabricated using commonly utilized methods for generating polymeric microfibers, including solution electrowriting (SEW) and fiber electropulling (FEP). [22][23][24][25][26][27][28][29] While traditional fused deposition modeling (FDM) 3D printing has a lower filament resolution limit of 100 μm, SEW and FEP can easily achieve filament sizes at or below the diameter of capillaries and are easily scalable to 3D arrays of filaments with highly controlled architecture. EC seeding onto highly porous microfiber lattices prior to encapsulation within a hydrogel-cell precursor solution can yield patent, EClined capillary-scale microvessels upon selective removal of the polymer microfiber.…”

Electrohydrodynamic 3D Printing of Aqueous Solutions

“…Collagen, [98][99][100][101] gelatin, [87,101,102] chitosan, [103] and silk fibroin have been the predominant biologically derived polymers studied for EHD processing to date. Processing of other synthetic and bio-based materials has also been reported including poly(2-ethyl-2-oxazoline), [104][105][106] poly(vinyl alcohol) (PVA), [107][108][109] alginate, [110] cellulose, [111] hyaluronic acid, [112,113] soy protein, [114,115] keratin, [116,117] potato protein, [118] and zein, [119][120][121][122][123] among others.…”

“…Processing of other synthetic and bio-based materials has also been reported including poly(2-ethyl-2-oxazoline), [104][105][106] poly(vinyl alcohol) (PVA), [107][108][109] alginate, [110] cellulose, [111] hyaluronic acid, [112,113] soy protein, [114,115] keratin, [116,117] potato protein, [118] and zein, [119][120][121][122][123] among others. [87,93,[101][102][103]120] In many of these cases, toxic, organic, or acidic solvents have been used for solution preparation. This restricts their applicability and makes the process more complex.…”