Calcium Phosphate and Calcium Phosphosilicate Mediated Drug Delivery and Imaging - Intracellular Delivery: Fundamentals and Applications - page 736

4.3 Bio-Imaging Using Calcium Phosphate Systems

Nanoparticulate delivery systems have the advantage of overcoming many of the
drawbacks associated with conventional contrast agents (organic dyes) such as poor
photostability, low quantum yield and instability in in vitro and in vivo applications.
An array of nanoparticulate material systems are employed for this application with
great emphasis on quantum dots and silica and gold nanoparticles.
With the incorporation of organic fluorophores and lanthanide ions, calcium
phosphate based nanoparticles have found wide use in imaging applications (Doat
2003, 2004 ; Lebugle 2006 ; Mondejar 2007 ; Ganesan 2008 ; Morgan 2008 ; Kester
2008 ; Altınoğlu 2008 ; Barth 2010 ; Al-Kattan 2010 ). Organic fluorophores that are
encapsulated in the calcium phosphosilicate particles span the optical spectrum
(Fig. 9 ) and permit analysis of cells using fluorescent microscopy and imaging of
whole mice in the near-infrared (Altınoğlu 2008 ; Barth 2010 ).
Lanthanides, such as europium (Eu) possess fluorescent properties (fluores-
cence emission at 620 nm) when doped into calcium phosphate crystals (Al-Kattan

Fig. 9 Fluorescence spectra of organic fluorophores encapsulated in calcium phosphosili-
cate nanoparticles . Inset shows the five fluorescent nanocolloids of CPSNP illuminated with a
UV lamp. From left to right, cascade blue, SAB, fluorescein, rhodamine WT, Cy3 Amidite
(Reproduced from Morgan ( 2008 ). With permission)