(520f) Using Chaotic Advection for Facile High-Throughput Fabrication of Ordered Multilayer Micro- and Nanostructures: Continuous Chaotic Printing

Today, tissue engineering is evolving exponentially and is now providing real solutions for creating biological models and solving clinical problems. However, several challenges still hinder the full potential of tissue engineering to generate models that recapitulate complex and large-size tissues and organs. Here, we introduce some advances in chaotic bioprinting, an additive manufacturing technique that enables the creation of complex biological structures at an unprecedented level of resolution and throughput.

Continuous chaotic printing uses chaotic advection for deterministic and continuous extrusion of fibers that have unique internal multilayered structures. In brief, two free-flowing materials are coextruded through a printhead containing a miniaturized Kenics static mixer (KSM) composed of multiple helicoidal elements. This produces a fiber with a well-defined internal multilayer microarchitecture at high throughput (>1.0 m min^-1), with the number and thickness of the internal lamellae determined by the number of mixing elements and the printhead diameter. The lamellae are generated according to successive bifurcations that yield a vast amount of inter-material surface area (~10² cm² cm^-3) at high resolution (~10 µm). This creates a new opportunity to produce structures with extremely high surface to volume. Comparison of experimental and computational results demonstrates that continuous chaotic 3D printing is a robust process with predictable output. The simplicity and high resolution of continuous chaotic printing strongly supports its potential use in novel applications.

Here, we illustrate the application of continuous chaotic bioprinting for the fabrication of complex multi-layered bacterial microcosmoi. We demonstrate that the degree of resolution achieved within these constructs can be finely controlled up to the range of a few microns of separation between layers. More importantly, we show that the degree of interface between bacterial layers greatly matters in terms of competition among the bacterial populations.

In a separate demonstration, we also construct tissue-like structures in which living layers of muscle cells evolve into a coherent segment of muscle. We also show that vascularization can be easily built into these constructs using a combination of sacrificial and permanent 3D printer “inks” and a multi-port modification to the chaotic printhead.

We are currently exploring more applications of chaotic printing in tissue engineering approaches, such as the fabrication of vascularized cancer models and the construction of multi-cell type tissue-like architectures where distinct mammalian cell layers share a high amount of common interface.

Different fields outside of biosciences and biotechnologies are also in need of simple and robust ways to create multilayered and multi-material structures to attain functionalities that monolithic materials simply cannot exhibit. We envision the application of chaotic printing to technological scenarios that could include the fabrication of batteries, superconductors, super catalytic surfaces, and 3D microfluidic reactors.