M. Terracciano

Internalization kinetics and cytoplasmic localization of functionalized diatomite nanoparticles in cancer cells by Raman imaging

Porous biosilica nanoparticles obtained from diatomites (DNPs) have been recently demonstrated to be non-toxic nanovectors of therapeutic agents in cancer cells. In this work, the internalization kinetics and intracellular spatial distribution of functionalized DNPs incubated with human lung epidermoid carcinoma cell line (H1355) up to 72u2009hours are investigated by Raman imaging. The label-free Raman results are compared with confocal fluorescence microscopy and photoluminescence (PL) data. Raman bands specifically assigned to DNPs and cellular components provide evidence that the nanovectors are internalized and co-localize with lipid environments. A considerable DNPs uptake in cells is observed within 6u2009hours, with equilibrium being achieved after 18u2009hours. The obtained data show the presence of DNPs up to 72u2009hours, without damage to cell viability or morphology. The PL measurements performed on DNPs not penetrating the cells at different incubation times are strongly correlated with the results obtained by Raman imaging and confocal microscopy analyses.

Gold decorated porous biosilica nanodevices for advanced medicine

Diatomite is a fossil material made of amorphous porous silica. In this work, polyethylene glycol (PEG)-modified diatomite NPs (PEG-DNPs) are decorated with gold NPs (AuNPs) by one-pot liquid-phase synthesis. Nanocomplexes (PEG-DNPs@AuNPs), with an average size of about 450 nm, are characterized by dynamic light scattering, electron microscopy, nitrogen adsorption/desorption analysis, UV-vis and photoluminescence spectroscopies. Preliminary studies on the use of the nanocomplex in nanomedicine are also presented. Tests performed incubating PEG-DNPs@AuNPs in physiological conditions reveal a good stability of material. Cellular uptake of labeled PEG-DNPs@AuNPs is investigated by confocal microscopy after incubation with human cervix epithelioid carcinoma (HeLa) cells up to 48 h: an efficient cytoplasmic localization is observed. In vitro cytotoxicity of nanocomplexes with a concentration up to 400 μg ml-1 for 72 h is also evaluated. The results suggest the use of PEG-DNPs@AuNPs as advanced nanodevices adding imaging features to the nanocomplexes, due to AuNPs as contrast agent.

Quantification and Reduction of the Residual Chemical Reactivity of Passivated Biodegradable Porous Silicon for Drug Delivery Applications

The chemical reactivity of as-anodized porous silicon is shown to have an adverse effect on a model drug (Lansoprazole) loaded into the pores. The silicon hydride surfaces can cause unwanted reactions with actives during storage or use. Techniques such as thermal oxidation or surface derivitization can lower the reactivity somewhat, by replacing the reactive silicon-hydride species with a more benign oxide or functional group. However, by using a trio of analytical techniques (fluorometric dye assay, HPLC assay, and chemography) we show that residual hydride is still likely to be present and only after combining thermal oxidation with surface derivitization can the residual reactivity be reduced to those values typically observed with sol-gel (porous) silica. Potential sources of residual reactivity are discussed, with reference to data obtained by trace metal analysis, residual solvents, and pH measurements.

Functionalization of macroporous silicon for optical detection of bacteria

Rapid detection of target bacteria is crucial issue in many areas of social interest to prevent harmful contamination for humans and the environment. Porous silicon (PSi), due to its peculiar physicochemical characteristics and well-defined optical properties, was used to fabricated a label-free PSi biosensor for bacteria detection by surface hydrosilylation and bioconjugation with Protein A.

Silica-Based Nanovectors: From Mother Nature to Biomedical Applications

Diatomite is a natural porous silica material of sedimentary origin, formed by remains of diatom skeletons called “frustules.” The abundance in many areas of the world and the peculiar physico-chemical properties made diatomite an intriguing material for several applications ranging from food production to pharmaceutics. However, diatomite is a material still rarely used in biomedical applications. In this chapter, the properties of diatom frustules reduced to nanoparticles, with an average diameter less than 350 nm, as potential drug vectors are described. Their biocompatibility, cellular uptake, and capability to transport molecules inside cancer cells are discussed. Preliminary studies of in vivo toxicity are also presented.

Natural and synthetic nanostructured materials for biomedical applications

Nanostructured materials, due to their peculiar physical and chemical properties, constitute the new class of functional supports for specific innovative applications. There is a strong competition between synthetic, man-made nanostructured materials and those coming directly from nature: the first ones can be precisely tailored by properly design and fabrication; the second ones are directly available without any cost of production. In this paper, we report our latest achievements on different materials, porous silicon, zinc oxide nanowires and diatomite powders, which belong to these categories.

Photoluminescence of graphene oxide integrated with silicon substrates

In this work we have investigated the photoluminescence signal emitted by graphene oxide (GO) nanosheets infiltrated in silanized porous silicon (PSi) matrix. We have demonstrated that a strong enhancement of the PL emitted from GO by a factor of almost 2.5 with respect to GO on crystalline silicon can be experimentally measured. This enhancement has been attributed to the high PSi specific area. In addition, we have observed a weak wavelength modulation of GO photoluminescence emission, this characteristic is very attractive and opens new perspectives for GO exploitation in innovative optoelectronic devices and high sensible fluorescent sensors.