Browsing by Author "Stigliano, Cinzia"
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Item Geometrical confinement of Gd(DOTA) molecules within mesoporous silicon nanoconstructs for MR imaging of cancer(Elsevier, 2014) Gizzatov, Ayrat; Stigliano, Cinzia; Ananta, Jeyerama S.; Sethi, Richa; Xu, Rong; Guven, Adem; Ramirez, Maricela; Shen, Haifa; Sood, Anil; Ferrari, Mauro; Wilson, Lon J.; Liu, Xuewu; Decuzzi, Paolo; Smalley Institute for Nanoscale Science and TechnologyPorous silicon has been used for the delivery of therapeutic and imaging agents in several biomedical applications. Here, mesoporous silicon nanoconstructs (SiMPs) with a discoidal shape and a sub-micrometer size (1,000 × 400 nm) have been conjugated with gadolinium-tetraazacyclododecane tetraacetic acid Gd(DOTA) molecules and proposed as contrast agents for Magnetic Resonance Imaging. The surface of the SiMPs with different porosities – small pore (SP: ~ 5 nm) and huge pore (HP: ~ 40 nm) – and of bulk, non-porous silica beads (1,000 nm in diameter) have been modified with covalently attached (3-aminopropyl)triethoxysilane (APTES) groups, conjugated with DOTA molecules, and reacted with an aqueous solution of GdCl3. The resulting Gd(DOTA) molecules confined within the small pores of the Gd-SiMPs achieve longitudinal relaxivities r1 of ~ 17 (mM·s)−1, which is 4 times greater than for free Gd(DOTA). This enhancement is ascribed to the confinement and stable chelation of Gd(DOTA) molecules within the SiMP mesoporous matrix. The resulting nanoconstructs possess no cytotoxicity and accumulate in ovarian tumors up to 2% of the injected dose per gram tissue, upon tail vein injection. All together this data suggests that Gd-SiMPs could be efficiently used for MR vascular imaging in cancer and other diseases.Item Hierarchically Structured Magnetic Nanoconstructs with Enhanced Relaxivity and Cooperative Tumor Accumulation(Wiley, 2014) Gizzatov, Ayrat; Key, Jaehong; Aryal, Santosh; Ananta, Jeyarama; Cervadoro, Antonio; Palange, Anna Lisa; Fasano, Matteo; Stigliano, Cinzia; Zhong, Meng; Di Mascolo, Daniele; Guven, Adem; Chiavazzo, Eliodoro; Asinari, Pietro; Liu, Xuewu; Ferrari, Mauro; Wilson, Lon J.; Decuzzi, Paolo; R.E. Smalley Institute for Nanoscale Science and TechnologyIron oxide nanoparticles are formidable multifunctional systems capable of contrast enhancement in magnetic resonance imaging, guidance under remote fields, heat generation, and biodegradation. Yet, this potential is underutilized in that each function manifests at different nanoparticle sizes. Here, sub-micrometer discoidal magnetic nanoconstructs are realized by confining 5 nm ultra-small super-paramagnetic iron oxide nanoparticles (USPIOs) within two different mesoporous structures, made out of silicon and polymers. These nanoconstructs exhibit transversal relaxivities up to ≈10 times (r 2 ≈ 835 mm −1 s−1) higher than conventional USPIOs and, under external magnetic fields, collectively cooperate to amplify tumor accumulation. The boost in r 2 relaxivity arises from the formation of mesoscopic USPIO clusters within the porous matrix, inducing a local reduction in water molecule mobility as demonstrated via molecular dynamics simulations. The cooperative accumulation under static magnetic field derives from the large amount of iron that can be loaded per nanoconstuct (up to ≈65 fg) and the consequential generation of significant inter-particle magnetic dipole interactions. In tumor bearing mice, the silicon-based nanoconstructs provide MRI contrast enhancement at much smaller doses of iron (≈0.5 mg of Fe kg−1 animal) as compared to current practice.