Light-assisted direct-write of 3D functional biomaterials

Abstract

Light-assisted 3D direct-printing of biomaterials and cellular-scaffolds has the potential to develop novel lab-on-a-chip devices (LOCs) for a variety of biomedical applications, from drug discovery and diagnostic testing to in vitro tissue engineering and regeneration. Direct-writing describes a broad family of fabrication methods that typically employ computer-controlled translational stages to manufacture structures at multi-length scales. This review focuses on light-assisted direct-write fabrication for generating 3D functional scaffolds with precise micro- and nano-architecture, using both synthetic as well as naturally derived biomaterials. Two bioprinting approaches are discussed in detail - projection printing and laser-based systems - where each method is capable of modulating multiple scaffold parameters, such as 3D architecture, mechanical properties (e.g. stiffness), Poisson's ratio, chemical gradients, biological cell distributions, and porosity. The light-assisted direct-writing techniques described in this review provide the reader with alternative approaches to fabricate 3D biomaterials for utility in LOCs.

Deterministically patterned biomimetic human iPSC-derived hepatic model via rapid 3D bioprinting

“…The application of the rapid 3D bioprinting process to our study allows the flexible use of digital masks (21,23,24) and thus facilitates the process of liver lobule pattern design and modification. Moreover, the projection optics of the system focuses light patterns at micrometer-level resolution, thus enabling the biofabrication of the liver lobule hydrogel construct within several seconds with minimal UV illumination.…”

“…The patterns were transferred to both GelMA and GMHA hydrogels by DLP-based 3D bioprinting technology (Fig. S2), which used a digital micromirror device (DMD) chip to generate photomasks based on input digital patterns for photopolymerization of the hydrogel solutions as previously described (21,23). To spatially pattern multiple types of cells and hydrogels, the digital masks were applied in a two-step sequential manner to create a first layer of hiPSC-derived hepatic cells supported by 5% (wt/vol) GelMA followed by a second complementary layer of supporting cells supported by 2.5% (wt/vol) GelMA and 1% GMHA (Fig.…”

“…Although a majority of these microfabrication techniques are limited to the generation of simple 2D geometries with selected materials, digital light processing (DLP)-based 3D printing provides superior speed and scalability for the fabrication of complex 3D microstructure (21,22). Moreover, this computer-aided, photopolymerizationbased technique offers the flexibility to fabricate a great variety of 3D designs and incorporate a wide range of functional elements including live cells, biomolecules, and nanoparticles (23-25).…”

A 3D Tissue-Printing Approach for Validation of Diffusion Tensor Imaging in Skeletal Muscle

“…30,31,34,35 Common photoinitiators include Irgacure 2959, Irgacure 651, Irgacure 819, 2-dimethoxy-2-phenylaceto-phenone, and lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP). 27 Upon stimulation by UV light, the photoinitiator generates free radicals locally. Then the free radicals attack the C]C bonds and generate acrylic monomers with free electrons, which react with the monomers and cross-link them into polymer networks.…”

“…22 These methods include two-photon laser direct writing, 23 inkjet 3D printing, 24 extrusion based 3D printing, 25 and digital light projection (DLP) based 3D printing. 26,27 Two-photon laser direct writing can achieve 100 nm resolution, yet this process would take days to fabricate a millimeter-size structure due to its point-by-point writing process. Both inkjet 3D printing and extrusion based 3D printing have a coarse spatial resolution, typically over 50 mm, rendering them impractical for fabricating skeletal muscle geometry, which is often smaller.…”