Dhananjay Thakur et al 2009 Nanotechnology 20 485601 doi:10.1088/0957-4484/20/48/485601
Dhananjay Thakur1, Shuang Deng2, Thierno Baldet2 and Jessica O Winter1,2,3,4
Show affiliationsThere has been great interest in the use of nanoparticles for imaging, particularly in multimodal applications (e.g., combination of MRI and fluorescence). Yet creating particles with multiple functionalities has been challenging. Here, we report the synthesis of pH sensitive, fluorescent–magnetic, nanocomposites created through a simple aqueous procedure. Separately synthesized superparamagnetic iron oxide nanoparticles and mercaptopropionic acid (MPA)-coated CdS quantum dots were crosslinked using 3-mercaptopropyl trimethoxysilane (MPS) as a bifunctional linker to yield CdS–iron oxide conjugates. Conjugates formed clusters of 0.1–1.0 µm diameter, with the smallest observed particle diameter ~50 nm. Particle solubility and photoluminescent (PL) intensity were sensitive to solution pH, with the highest PL intensity and stability obtained at pH values <3.0 and MPS:Cd:Fe ratios of 1:10:1. pH sensitivity is believed to result from changes in nanoparticle solubility within the silica-based matrix. Given these unique properties, this material might find application in separation, pH sensitive detection (e.g., endosomal tracking) and biosensing.
87.85.Qr Nanotechnologies-design
87.61.-c Magnetic resonance imaging
75.50.Tt Fine-particle systems; nanocrystalline materials
81.16.-c Methods of nanofabrication and processing
Issue 48 (2 December 2009)
Received 10 July 2009, in final form 30 September 2009
Published 30 October 2009
Dhananjay Thakur et al 2009 Nanotechnology 20 485601
A J Accioly et al 1993 Class. Quantum Grav. 10 L215
Carolyn McKerracher and David I Thwaites 2006 Phys. Med. Biol. 51 3315
Olaf Post 2005 J. Phys. A: Math. Gen. 38 4917
Adel Hamdi 2009 Inverse Problems 25 115009
Ying Jiang et al 2004 J. Phys.: Condens. Matter 16 2773
Hyun Chan Pyo et al 2005 Phys. Med. Biol. 50 3183
T. J. Cox et al 2004 ApJ 607 L87
J Grosser et al 1994 J. Phys. B: At. Mol. Opt. Phys. 27 L367
Wenbo Yan et al 2006 J. Phys. D: Appl. Phys. 39 4245