Multiphoton Induced Fluorescence and Second Harmonic Imaging of Drug- infused arterial walls for Non-invasive photo-polymerizable stents

Author: Tochukwu Emeakaroha, Department of Nanoscience and Nanoengineering

Contributor: Divya Kota, Department of Nanoscience and Nanoengineering

Contributor: Sam Young, Alumend LLC, Sioux Falls, SD

Contributor: Ron Utecht, Alumend LLC, Sioux Falls, SD

Mentor: Dr. Steve Smith, Department of Nanoscience and Nanoengineering

We developed a spectrally resolved multi-photon imaging system based on a closed-loop piezoelectric stage, a transmission grating, and an EMCCD. The method allows detailed analysis of the spectrally resolved signals, including deconvolution of the resulting emission peaks, and precise differentiation of the resulting spectroscopic signals. To improve the spatial resolution, we are implementing adaptive optics and a computational super resolution method known as pixel reassignment. We present multi-photon induced fluorescence, second harmonic and fluorescence lifetime imaging analysis supporting the development of non-invasive photo-polymerizable scaffolds for treatment of peripheral artery disease, a technology developed by Alumend, LLC, currently undergoing clinical trials and licensed by Alucent Medical. We report a comparison of the second harmonic generation and two photon induced fluorescence imaging in drug-infused arteries and compare these to fluorescence lifetime images. Primary signals from the endogenous fluorescence, drug fluorescence and second harmonic generation, prevalent in collagen, are compared. Of interest, we observe the photo-chemical modification of the drug fluorescence emission energy and lifetime in the adventitia, a region of the arterial wall composed primarily of collagen.