BIOE Honors Program Defense: Hannah Horng

Monday, April 15, 2019
9:00 a.m.
A. James Clark Hall, Room 3104
Dr. Kim Stroka
kstroka@umd.edu

Hannah Horng

Biomimetic Microvascular Tissue Phantoms Fabricated with Two-Photon 3D Printing

In recent years, several devices for retinal oximetry have been developed to diagnose conditions linked to abnormal oxygen saturation in the retina. Phantoms that simulate tissue microvasculature may provide tools to facilitate development and assessment of novel biophotonic devices for retinal oximetry. A 3D-printing approach has already been shown to be successful in phantoms of neural vasculature and presents a method of achieving high geometric complexity that mimics the distribution of real vessels. Of the 3D printing technologies, two-photon direct laser writing has the highest feature resolution, reaching nanometer scale, and has been applied to fabrication of devices in photonics, biology, and microfluidics.

In this study, we demonstrate that two-photon direct laser writing can be used to fabricate microscale phantoms of retinal vasculature using three approaches. The first involves printing a planar model of retinal vasculature using solid 17.5 μm vessels. The resulting model exhibited high autofluorescence at 465 nm excitation, making it suitable for mapping out the geometry of a model. The second involves using a syringe with a custom injection module to inject a colored dye into sections of a 2D model of retinal vasculature. This approach is shown to be viable for channels of .1 mm diameter or higher. The third involves printing channels within a PDMS device, allowing for a sizeable reduction in channel diameter down to 17.5 μm. The technique was applied to both a simple bifurcation model as well as to a full planar model of retinal vasculature, and fluid perfusion into both the printed channels and the PDMS indent was shown using IR700 dye solution and confocal microscopy. We conclude that that two-photon direct laser writing can be used to fabricate biomimetically complex structures with biologically relevant diameters that can be used to circulate fluid and imaged using confocal fluorescence microscopy.

 

 

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