title: In-vivo photoacoustic microscopy of nanoshell extravasation from solid tumor vasculature.
abstract: In this study, high resolution backward-mode photoacoustic microscopy (PAM) is used to noninvasively image progressive extravasation and accumulation of nanoshells within a solid tumor in vivo. PAM takes advantage of the strong near-infrared absorption of nanoshells and their extravasation tendency from leaky tumor vasculatures for imaging. Subcutaneous tumors are grown on immunocompetent BALB/c mice. Polyethylene glycol (PEGylated) nanoshells with a peak optical absorption at approximately 800 nm are intravenously administered. With an 800-nm laser source, a prescan prior to nanoshell injection is taken to determine the background that is free of nanoshell accumulation. After injection, the 3-D nanoshell distribution at the tumor foci is monitored by PAM for 6 h. Experimental results show that accumulated nanoshells delineate the tumor position. Nanoshell accumulation is heterogeneous in tumors: more concentrated within the tumor cortex and largely absent from the tumor core. Because nanoshells have been recently demonstrated to enhance thermal therapy of subcutaneous tumors, we anticipate that PAM will be an important aid before, during, and after nanoshell thermal therapy.
authors.affiliation: National Tsing Hua University, Department of Electrical Engineering, Hsinchu, 30013, Taiwan.
authors.forename: Meng-Lin
authors.initials: ML
authors.lastname: Li
authors.forename: James Chunjay
authors.initials: JC
authors.lastname: Wang
authors.forename: Jon A
authors.initials: JA
authors.lastname: Schwartz
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Gill-Sharp
authors.forename: George
authors.initials: G
authors.lastname: Stoica
authors.forename: Lihong V
authors.initials: LV
authors.lastname: Wang
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000098:blood supply* / Q000000981:diagnostic imaging*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005119:Extravasation of Diagnostic and Therapeutic Materials / Q000000981:diagnostic imaging*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D051379:Mice; D008807:Mice, Inbred BALB C; D049329:Nanostructures / Q000627:therapeutic use / Q000648:ultrastructure*; D009389:Neovascularization, Pathologic / Q000000981:diagnostic imaging*