PSi NPs Research Articles

Multifunctional porous silicon nanoparticles for cancer theranostics

Nanomaterials provide a unique platform for the development of theranostic systems that combine diagnostic imaging modalities with a therapeutic payload in a single probe. In this work, dual-labeled iRGD-modified multifunctional porous silicon nanoparticles (PSi NPs) were prepared from dibenzocyclooctyl (DBCO) modified PSi NPs by strain-promoted azide-alkyne cycloaddition (SPAAC) click chemistry. Hydrophobic antiangiogenic drug, sorafenib, was loaded into the modified PSi NPs to enhance the drug dissolution rate and improve cancer therapy. Radiolabeling of the developed system with 111In enabled the monitoring of the in vivo biodistribution of the nanocarrier by single photon emission computed tomography (SPECT) in an ectopic PC3-MM2 mouse xenograft model. Fluorescent labeling with Alexa Fluor 488 was used to determine the long-term biodistribution of the nanocarrier by immunofluorescence at the tissue level ex vivo. Modification of the PSi NPs with an iRGD peptide enhanced the tumor uptake of the NPs when administered intravenously. After intratumoral delivery the NPs were retained in the tumor, resulting in efficient tumor growth suppression with particle-loaded sorafenib compared to the free drug. The presented multifunctional PSi NPs highlight the utility of constructing a theranostic nanosystems for simultaneous investigations of the in vivo behavior of the nanocarriers and their drug delivery efficiency, facilitating the selection of the most promising materials for further NP development.

Porous silicon nanoparticles as a nanophotocathode for photoelectrochemical water splitting

An investigation on the nanophotocathode fabrication using electrochemically anodised pSi NPs for photoelectrochemical water splitting.

Nitric oxide-releasing porous silicon nanoparticles.

In this study, the ability of porous silicon nanoparticles (PSi NPs) to entrap and deliver nitric oxide (NO) as an effective antibacterial agent is tested against different Gram-positive and Gram-negative bacteria. NO was entrapped inside PSi NPs functionalized by means of the thermal hydrocarbonization (THC) process. Subsequent reduction of nitrite in the presence of d-glucose led to the production of large NO payloads without reducing the biocompatibility of the PSi NPs with mammalian cells. The resulting PSi NPs demonstrated sustained release of NO and showed remarkable antibacterial efficiency and anti-biofilm-forming properties. These results will set the stage to develop antimicrobial nanoparticle formulations for applications in chronic wound treatment.

Conjugation of NaGdF4 upconverting nanoparticles on silica nanospheres as contrast agents for multi-modality imaging

Here, we report the covalently conjugation of lanthanide doped NaGdF4:Yb3+, Er3+@NaGdF4 upconverting nanoparticles (UCNPs) on methylphosphonate functionalized silica nanospheres (pSi NPs) for in vivo upconversion luminescence (UCL), T1-weighted magnetic resonance (MR), and X-ray computed tomography (CT) multi-modality imaging. The nanocomposites (pSi@UCNPs) were synthesized by a facile ligand exchange strategy. The hydrophobic pSi@UCNPs were transferred into aqueous solution by surface coating Pluronic F127. The Pluronic F127 coated pSi@UCNPs (pSi@UCNPs@F127) exhibit excellent stability in biological medium, inappreciable cytotoxicity and negligible organ toxicity. The pSi@UCNPs@F127 also shows brighter UCL, and higher CT/MR enhancements than that of Pluronic F127 coated NaGdF4:Yb3+, Er3+@NaGdF4 UCNP. In detail, the capability of pSi@UCNPs@F127 as high performance contrast agents for in vivo multi-modality (UCL/MR/CT) imaging is evaluated successfully through small-animal experiments.

The Scattering of Positrons and Positronium by Atoms in the Close-Coupling Approximation

We present some recent results obtained within the close-coupling approximation for both positron and positronium scattering by atoms. We begin by discussing a generalization of the method of Vincent and Phatak to study the formation of Psin Ps collisions with H(1s) in a simplified model. The important result of this calculation is that the overall Coulomb interaction which is present in the rearrangement channel is treated exactly. We also present results for positronium formation and ionization for positron scattering by argon atoms. The present calculations are for transitions from the Αr(3s 2 ) subshell and show the importance of the coupling to the continuum. PACS numbers: 36.10.-k, 34.70.+e