title: Label-free bond-selective imaging by listening to vibrationally excited molecules.
abstract: We report the realization of vibrational photoacoustic (VPA) microscopy using optical excitation of molecular overtone vibration and acoustic detection of the resultant pressure transients. Our approach eliminates the tissue scattering problem encountered in near-infrared spectroscopy and enables depth-resolved signal collection. The 2nd overtone of the CH bond stretch around 8300  cm(-1), where blood interference is minimal, is excited. We demonstrate 3D VPA imaging of lipid-rich atherosclerotic plaques by excitation from the artery lumen, and lipid storage in live Drosophila larvae, with millimeter scale penetration depth [corrected].
authors.affiliation: Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Han-Wei
authors.initials: HW
authors.lastname: Wang
authors.forename: Ning
authors.initials: N
authors.lastname: Chai
authors.forename: Pu
authors.initials: P
authors.lastname: Wang
authors.forename: Song
authors.initials: S
authors.lastname: Hu
authors.forename: Wei
authors.initials: W
authors.lastname: Dou
authors.forename: David
authors.initials: D
authors.lastname: Umulis
authors.forename: Lihong V
authors.initials: LV
authors.lastname: Wang
authors.forename: Michael
authors.initials: M
authors.lastname: Sturek
authors.forename: Robert
authors.initials: R
authors.lastname: Lucht
authors.forename: Ji-Xin
authors.initials: JX
authors.lastname: Cheng
mesh_terms: D000818:Animals; D001314:Auscultation; D004331:Drosophila melanogaster; D005216:Fat Body; D007814:Larva; D033401:Microscopy, Acoustic / Q000379:methods*; D057054:Molecular Imaging / Q000379:methods*; D055095:Optics and Photonics; D058226:Plaque, Atherosclerotic / Q000473:pathology*; D019265:Spectroscopy, Near-Infrared / Q000379:methods; D014732:Vibration