Dual-mode photoacoustic microscopy of carbon nanotube incorporated scaffolds in blood and biological tissues

Abstract

Three-dimensional scaffolds provide physical support and an adjustable microenvironment to facilitate vascularization of ischemic tissues; however, in vivo imaging of scaffold functioning is still challenging. Micro-CT, the current frequentlyused imaging modality for scaffold characterization, provides poor contrast for wet scaffold, which limits its in vivo applications. In this paper, dual modes of photoacoustic microscopy (PAM), using acoustic resolution PAM (AR-PAM) and optical resolution PAM (OR-PAM), were employed for imaging scaffolds in blood as well as in chicken breast tissues. By choosing different wavelengths, 570 nm and 638 nm, we spectroscopically differentiated the photoacoustic signals generated from blood and from carbon nanotube incorporated scaffolds. The ex vivo experiments demonstrated a lateral resolution of 45 μm and a maximum penetration of ~2 mm for AR-PAM, and a lateral resolution of 3 μm and a maximum penetration of ~660 μm for OR-PAM. OR-PAM further quantified the average pore size of scaffolds to be 100-200 μm in diameter. Our results suggest that PAM is a promising tool for in vivo monitoring of scaffold-induced angiogenesis as well as the degradability of scaffolds themselves.

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