Optical microscopy images of PC3 human prostate cancer cells (control) grown for 24 h (A) in the absence of nanoparticles, and in the presence of (B) Mag and (C) Mag@SiO2 nanoparticles followed by three washings with PBS.

<p>Optical microscopy images of PC3 human prostate cancer cells (control) grown for 24 h (A) in the absence of nanoparticles, and in the presence of (B) Mag and (C) Mag@SiO2 nanoparticles followed by three washings with PBS.</p

XRD patterns obtained from Mag and Mag@SiO2 nanoparticles.

<p>XRD peaks with corresponding Bragg reflections of magnetite have been indicated. (*) corresponds to the XRD peak arising from a mixed Fe-Si phase.</p

Evaluation of Mag@SiO2 nanoparticles as a T2 MR contrast agent is shown in the form of % signal enhancement with increasing concentration of Fe using a 3 Tesla MR scanner.

<p>Panel A shows the studies performed in phantoms for particles in suspension, while panel B shows the similar studies in PC3 human prostate cancer cells after nanoparticles uptake for 24 h. Corresponding T2-weighted MR images of different samples, showing the image darkening effect with increasing Fe concentration are also shown under each bar.</p

TEM images of (A) Mag and (B) Mag@SiO2 core-shell nanoparticles.

<p>Insets show the respective higher resolution TEM images.</p

Magnetic hysteresis curve of Mag@SiO2 nanoparticles used for MR imaging of tumor cells and tissues.

<p>Magnetic hysteresis curve of Mag@SiO2 nanoparticles used for MR imaging of tumor cells and tissues.</p

T2-weighted MR images of nude mice with breast tumor obtained (A) before and (B) after injection of MR contrast agent, obtained using a 3 Tesla MR scanner.

<p>Mouse 2 was injected with Mag@SiO2 nanoparticles as T2 contrast agent, while Mouse 1 was injected with saline as a control. Tumor sites in the control (mouse 1) and in the treated mouse (mouse 2) have been labelled as blue and red circles respectively. Panels C and D show the higher magnification transverse section images of tumor site corresponding to Panels A and B respectively, wherein tumor region injected with MR contrast agent has been highlighted using white circles.</p

Biocompatibility of Mag@SiO2 nanoparticles assessed using MTT assay after their exposure to PC3 cancer cells for 24 h with respect to different Fe concentration in Mag@SiO2 nanoparticles.

<p>Biocompatibility of Mag@SiO2 nanoparticles assessed using MTT assay after their exposure to PC3 cancer cells for 24 h with respect to different Fe concentration in Mag@SiO2 nanoparticles.</p