title: Theranostics with multifunctional magnetic gold nanoshells: photothermal therapy and t2* magnetic resonance imaging.
abstract: OBJECTIVE
  to investigate the multifunctional imaging and therapeutic capabilities of core-shell nanoparticles composed of a superparamagnetic iron oxide (SPIO) core and a gold shell (SPIO@AuNS).
  
  
  METHODS
  the magnetic/optical properties of SPIO@AuNS were examined both in an agar gel phantom and in vivo by evaluating contrast-enhanced magnetic resonance imaging (MRI) and by measuring near-infrared (NIR) light-induced temperature changes mediated by SPIO@AuNS. In addition, the biodistribution and pharmacokinetics of In-labeled SPIO@AuNS after intravenous injection in mice bearing A431 tumors were evaluated in the presence and absence of an external magnet.
  
  
  RESULTS
  : In agar phantoms containing SPIO@AuNS, a significant contrast enhancement in T2-weighted MRI was observed and a linear increase in temperature was observed with increasing concentration and laser output power when irradiated with NIR light centered at an 808 nm. In vivo, T2*-MRI delineated SPIO@AuNS and magnetic resonance temperature imaging of the same tumors revealed significant temperature elevations when intratumorally injected with SPIO@AuNS (1 × 10 particles/mouse) and irradiated with NIR light (65.70°C ± 0.69°C vs. 44.23°C ± 0.24°C for saline + laser). Biodistribution studies in mice intravenously injected with In-labeled-SPIO@AuNS(1 × 10 particles/mouse) had an approximately 2-fold increase in SPIO@AuNS delivered into tumors in the presence of an external magnet compared with tumors without the magnet.
  
  
  CONCLUSIONS
  owing to its ability to mediate efficient photothermal ablation of cancer cells under MRI guidance, as well as the ability to be directed to solid tumors with an external magnetic field gradient, multifunctional SPIO@AuNS is a promising theranostic nanoplatform.
authors.affiliation: Departments of Experimental Diagnostic Imaging, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Marites P
authors.initials: MP
authors.lastname: Melancon
authors.forename: Andrew
authors.initials: A
authors.lastname: Elliott
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Ji
authors.forename: Anil
authors.initials: A
authors.lastname: Shetty
authors.forename: Zhi
authors.initials: Z
authors.lastname: Yang
authors.forename: Mei
authors.initials: M
authors.lastname: Tian
authors.forename: Brian
authors.initials: B
authors.lastname: Taylor
authors.forename: R Jason
authors.initials: RJ
authors.lastname: Stafford
authors.forename: Chun
authors.initials: C
authors.lastname: Li
mesh_terms: D000465:Algorithms; D000818:Animals; D004195:Disease Models, Animal; D005290:Ferric Compounds; D006046:Gold; D006358:Hot Temperature / Q000627:therapeutic use*; D007204:Indium; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D057145:Nanoshells; D009369:Neoplasms / Q000175:diagnosis* / Q000473:pathology; D019047:Phantoms, Imaging
chemical_list: D005290:Ferric Compounds; D007204:Indium; C000499:ferric oxide; D006046:Gold