Biological activity of gold nanoparticles combined with the NFL-TBS.40-63 peptide, or with other cell penetrating peptides, on rat glioblastoma cells.

Targeting, detecting, and destroying selectively cancer cells or specific organelles is a major challenge of nanomedicine. Recently, a new methodology was conceived to synthesize gold nanoparticles combined with a peptide having a C-terminal biotin (BIOT-NFL-peptide). This methodology called "Method IN" allows specific interactions between the BIOT-NFL-peptide, the polyethylene glycol diacid (PEG-COOH) and the gold salt (Au III) to produce multifunctional hybrid nano-carriers called BIOT-NFL-PEG-AuNPs. Here, we show that it is possible to use this strategy to synthesize multifunctional hybrid nano-carriers with other cell-penetrating peptides including TAT and Vim-peptides. Ex-vivo studies on F98 rat glioblastoma cells show that these new nanovectors acquire the cellular entry function of peptides and the gold particles make it possible to visualize by electron microscopy their localization in organelles. Thus, these new multifunctional nanovectors offer promising possibilities for the theranostic field, including the cell-penetrating property of the peptide, the intra-organelle localization of gold particles and their possible thermoplasmonic properties, as well as the stealth property of PEG.

nPEG-TiO2 nanoparticles: a facile route to elaborate nanostructured surfaces for biological applications.

We report the synthesis of diacid-terminated PEG-functionalized cubic TiO(2) nanocrystals by a simple one-step solvothermal method, and their further use to form nanostructured surfaces for protein immobilization. The relevance and major interest of the so-obtained nanocrystals are the presence of terminal carboxylic acid groups at their surface, as confirmed by infrared analyses, in addition to the surrounding PEG chains, essential to avoid non specific interactions. These functional chemical groups were used to (i) immobilize the synthesized nanocubes on a cysteamine-modified Au surface, and to (ii) attach proteins via a presumable covalent link. AFM images show that the shapes and the narrow size distribution of the nanocubes, observed by TEM, were preserved after their immobilization on the modified Au surface. Moreover, the efficiency and specificity of antigen recognition were demonstrated using spectroscopic analyses. Our successful approach provides a versatile and facile way to elaborate specific and sensitive nanostructured surfaces for biosensors.

Heterogeneous optochemical VOC sensing layers selected by ESI-mass spectrometry.

Spin-coated films of 29H,31H-tetra-4-(2,4-di-tert-amylphenoxy)phthalocyanine (H(2)Pc) and [kappaP,mu-kappaS-(dppeS)Pt(CH(3))](2)[BF(4)](2) have been used as sensing layers deposited in thin film form for the detection of VOCs. The sensing behaviour of the blend was predicted on the basis of mass spectrometric determinations performed on H(2)Pc/Pt-complex solutions, by monitoring the formation of gas-phase ions at the electrospray interface. The addition of small amounts of acetonitrile produced a [M+41](+) peak whereas the addition of similar amounts of methanol, ethanol and isopropyl alcohol did not give the corresponding [M+ROH](+) species. These results were confirmed by sensing tests. A pure phthalocyanine optosensing element did not show relevant selectivity. Conversely, the heterogeneous sensing layer obtained by spin-coating deposition of a Pt-complex/H(2)Pc blend allowed the sensing of acetonitrile vapours with respect to the above mentioned alcohols.

Surface plamon resonance imaging of DNA based biosensors for potential applications in food analysis.

The adsorption processes of oligonucleotides immobilised onto suitable photolithographic patterned gold substrates have been investigated in aqueous buffer solution by using a home made surface plasmon resonance (SPR) imaging equipment. A rapid self-assembled method for the construction of DNA chips to be used in SPR imaging experiments have been followed. The immobilised DNA molecules (probes) adopted in our SPR experiments anchored to a gold surface via thiol group were 5'thiol-modified containing a (CH(2))(15) tail. The hybridisation processes taking place with its complementary sequence have been observed and characterized by monitoring phenomena by a SPR imaging system. The two analysed oligonucleotides (probes and target) are of interest in plant gene biotechnological application and differing for the presence at the 5'-end of a poly T16 spacer. Dynamic investigation of smallest changes in SPR imaging pictures performed in liquid phase in the presence of DNA complementary probes have been performed. Quantitative information in terms of threshold of sensitivity has been extracted by using a specific images treatment.

Au nanoparticles prepared by physical method on Si and sapphire substrates for biosensor applications.

Gold nanoparticles heavily functionalized with oligonucleotides have been used in a variety of DNA detection methods. The optical properties of three-dimensional aggregates of Au nanoparticles in solution or deposited onto suitable surfaces have been analyzed to detect hybridization processes of specific DNA sequences as possible alternatives to fluorescent labeling methods. This paper reports on the preparation of gold nanoparticles directly deposited onto the surface of silicon (Si) and sapphire (Al2O3) substrates by a physical methodology, consisting in the thermal evaporation of a thin Au film and its successive annealing. The method guarantees the preparation of monodispersed single-crystal Au nanoparticles with a strong surface plasmon resonance (SPR) peak centered at about 540 nm. We show that the changes of SPR excitation before and after DNA functionalization and subsequent hybridization of Au nanoparticles immobilized onto Si and Al2O3 substrates can be exploited to fabricate specific biosensors devices in solid phase.

Liquid phase SPR imaging experiments for biosensors applications.

Surface plasmon resonance (SPR) has recently gained attention as a label-free method for the detection of biological molecules binding onto functionalised surfaces. It is one of the most sensitive detection method for monitor variations in the thickness and refractive index in ultra-thin films. Here, the adsorption processes of oligonucleotides onto gold substrates have been investigated in aqueous buffer solution using SPR imaging measurements. The hybridization of a thiol-modified, single stranded oligonucleotide anchored to a gold surface via thiol group, with its complementary sequence has been observed and characterised monitoring the hybridization process by SPR equipment. In situ investigation of smallest changes in SPR imaging measurements dynamically performed in liquid phase in the presence of DNA complementary probes was performed. Infrared spectroscopy and scanning electron microscopy characterisation of the functionalised gold surfaces of the biosensor were compared with the images obtained by SPR experimental apparatus.