title: Palladium nanosheets as highly stable and effective contrast agents for in vivo photoacoustic molecular imaging.
abstract: A stable and efficient contrast agent is highly desirable for photoacoustic (PA) imaging applications. Recently gold nanostructures have been widely reported and studied for PA imaging and photothermal therapy. However, the structures of the nonspherical gold nanoparticles are easily destroyed after laser irradiation and thus may fail to complete the intended tasks. In this study, we propose to apply palladium nanosheets (PNSs), with strong optical absorption in the near-infrared (NIR) region, as a new class of exogenous PA contrast agents. PA and ultrasound (US) images were acquired sequentially by a portable and fast photoacoustic tomography (PAT) system with a hand-held transducer. Significant and long-lasting imaging enhancement in SCC7 head and neck squamous cell carcinoma was successfully observed in mice by PAT over time after tail vein administration of PNSs. The morphology and functional perfusion of the tumors were delineated in PA images due to the nanoparticle accumulation. PAT of the main organs was also conducted ex vivo to trace the fate of PNSs, which was further validated by inductively coupled plasma atomic emission spectrometry (ICP-AES). No obvious toxic effect was observed by in vitro MTT assay and ex vivo histological examination 7 days after PNS administration. With the combination of a portable imaging instrument and signal specificity, PNSs might be applied as stable and effective agents for photoacoustic cancer detection, diagnosis and treatment guidance.
authors: Laboratory of Molecular Imaging and Nanomedicine (LOMIN), National Institute of Biomedical Imaging and Bioengineering (NIBIB), National Institutes of Health (NIH), Bethesda, Maryland 20892, USA. shawn.chen@nih.gov.
authors: Liming
authors: L
authors: Nie
authors: Mei
authors: M
authors: Chen
authors: Xiaolian
authors: X
authors: Sun
authors: Pengfei
authors: P
authors: Rong
authors: Nanfeng
authors: N
authors: Zheng
authors: Xiaoyuan
authors: X
authors: Chen
mesh_terms: D000162:Acoustics; D000818:Animals; D045744:Cell Line, Tumor; D002470:Cell Survival; D003287:Contrast Media / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry; D051379:Mice; D049329:Nanostructures / Q000737:chemistry*; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000175:diagnosis; D055095:Optics and Photonics; D010165:Palladium / Q000737:chemistry*; D010477:Perfusion; D010777:Photochemistry / Q000379:methods*; D013778:Tetrazolium Salts / Q000737:chemistry; D013844:Thiazoles / Q000737:chemistry; D014018:Tissue Distribution; D014054:Tomography / Q000295:instrumentation / Q000379:methods*; D014159:Transducers
chemical_list: D003287:Contrast Media; D013778:Tetrazolium Salts; D013844:Thiazoles; D010165:Palladium; D006046:Gold; C022616:thiazolyl blue