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Published March 26, 2012 | Published
Journal Article Open

Multiscale Photoacoustic Microscopy of Single-Walled Carbon Nanotube-Incorporated Tissue Engineering Scaffolds


Three-dimensional polymeric scaffolds provide structural support and function as substrates for cells and bioactive molecules necessary for tissue regeneration. Noninvasive real-time imaging of scaffolds and/or the process of tissue formation within the scaffold remains a challenge. Microcomputed tomography, the widely used technique to characterize polymeric scaffolds, shows poor contrast for scaffolds immersed in biological fluids, thereby limiting its utilities under physiological conditions. In this article, multiscale photoacoustic microscopy (PAM), consisting of both acoustic-resolution PAM (AR-PAM) and optical-resolution PAM (OR-PAM), was employed to image and characterize single-walled carbon-nanotube (SWNT)–incorporated poly(lactic-co-glycolic acid) polymer scaffolds immersed in biological buffer. SWNTs were incorporated to reinforce the mechanical properties of the scaffolds, and to enhance the photoacoustic signal from the scaffolds. By choosing excitation wavelengths of 570 and 638 nm, multiscale PAM could spectroscopically differentiate the photoacoustic signals generated from blood and from carbon-nanotube-incorporated scaffolds. OR-PAM, providing a fine lateral resolution of 2.6 μm with an adequate tissue penetration of 660 μm, successfully quantified the average porosity and pore size of the scaffolds to be 86.5%±1.2% and 153±15 μm in diameter, respectively. AR-PAM further extended the tissue penetration to 2 mm at the expense of lateral resolution (45 μm). Our results suggest that PAM is a promising tool for noninvasive real-time imaging and monitoring of tissue engineering scaffolds in vitro, and in vivo under physiological conditions.

Additional Information

© 2012 Mary Ann Liebert, Inc. publishers. Published in Volume: 18 Issue 4: March 26, 2012; Online Ahead of Print: December 22, 2011; Online Ahead of Editing: November 15, 2011. We appreciate Professor James Ballard's close reading of the manuscript. This work was sponsored by the National Institutes of Health grants No. 1DP2OD007394-01 (to S.B.), No. R01 EB000712, No. R01 EB008085, No. R01 CA134539, and No. U54 CA136398 (Network for Translational Research) (to L.V.W.). Disclosure Statement: L.V.W. has a financial interest in Microphotoacoustics, Inc., and Endra, Inc., which, however, did not support this work. Others claim no competing financial interests.

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