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Amino-terminated surfaces can be effectively obtained by means of silanizing agents, realizing surfaces suitable for the purification of biomarkers of several pathologies. Since the level of biomarkers, such as microRNAs and cell-free DNA, into circulation may be extremely low, new and ameliorated capturing molecules and protocols are highly required. In this work, a new silane, acetone-imine propyl trimethoxysilane (AIPTMS), is synthesized with a simple and elegant reaction, via the nucleophilic addition of the primary amino group to the carbonyl group of acetone. AIPTMS and APTMS were used to silanize silicon oxide surfaces, which were characterized chemically (XPS) and morphologically (AFM). The two types of surfaces were chemically similar, but behaved very differently both for surface morphology and functional properties. The AIPTMS-modified surface was indeed very smooth and homogeneous with respect to the APTMS-modified surface. Moreover, the AIPTMS surface captured larger amounts of nucleic acids almost immediately after preparation, while APTMS-based functional surfaces needed longer time to reach comparable efficiency. AIPTMS shows several advantages over standard aminosilanes, as it realizes a more homogeneous surface coverage that, in turn, produces an improved response towards the capture of nucleic acids. AIPTMS is a very promising reagent for the reliable and reproducible preparation of active biofunctional surfaces for the purification and analysis of circulating biomarkers.

Bilayer membranes for food packaging applications were prepared by depositing on polylactic acid (PLA) substrates pure cellulose nanofibers' (CNF) coatings and nanocomposite coatings made of CNF with dispersed TiO2 nanoparticles. The gas barrier properties of the bilayer membranes were studied by gas phase permeation technique using CO2, N2, D2, He and ambient air as test gases. Few micrometer thick pure and nanocomposite CNF coatings act as effective gas permeation barriers impeding the CO2, N2 and O2 transport and reducing the He and D2 transport rates by 3 orders of magnitude when compared with the PLA substrate. Gas transport through the coatings obeys the solution-diffusion mechanism: D2 permeation process shows activation energy values of 44 ± 6 kJ/mol and 40 ± 6 kJ/mol in the pure and nanocomposite CNF coating, respectively. The addition of the TiO2 nanoparticles reduces the penetrant diffusivity by increasing the tortuosity of the penetrant migration path but does not affect the gas barrier performances. UV–Vis spectroscopy analyses show that the optical transparency of the PLA support is slightly decreased by the CNF coating: at 600 nm the optical transmittance decreases, in fact, from 95% to 91%. TiO2 nanoparticles strongly absorb UV radiation and slightly reduce the PLA transparency in the optical range due to light scattering effects.

The interest towards aptamer-based surfaces in the field of bioaffinity assays is constantly growing. A crucial aspect is related to the ability of maintaining the high specificity of these molecules once immobilized on the surface. In this article we compare the immobilization of aptamers on a silanized silicon nitride surface as well as on a soft polymeric layer. An innovative immobilization approach, based on a copolymer, N-dimethylacrylamide-N-acryloyloxysuccinimide-3-(trimethoxysilyl)propylmethacrylate (DMA-NAS-MAPS) coating, able to crosslink itself to the substrate and to bind amino-modified biomolecules is proposed. Comparing this coating with a more classical functionalization process based on silane chemistry, we propose that the better results obtained on the polymeric layer are due to an increased binding efficiency of the aptamers bound to a soft material. The high specificity of immobilized DNA-aptamers is demonstrated using two sequences specific for thrombin detection and a non-sense sequence as negative control. The coating provides higher sensitivity compared to classical self-assembled silane coatings, probably due to a better mobility of bound aptamers. The aptamer immobilization on both surfaces was characterized and optimized using atomic force microscopy, X-ray photoelectron spectroscopy, contact angle and fluorescence microscopy. The comparison between the two different functionalizations highlights the better performances of the copolymer coating in terms of protein recognition, demonstrating thrombin detection down to 0.011 nM in buffer solution and 4.9 nM in complete human serum. Moreover, the localized immobilization of the aptameric sequences, utilized in this work, suggests the possibility of employing this platform also for multianalyte detection.

Selective functionalization of the external/internal pore surface of porous silicon is of interest for the numerous potential applications of this material, in particular in pharmacology. With the aim of obtaining porous silicon platforms compatible with the aqueous environment and providing hydrophobic pores to load poorly water soluble molecules, we set-up a three step functionalization procedure consisting in two hydrosilylation reactions separated by the selective etching of the external surface. This procedure was applied both, to porous layers and porous microparticles. The characterization of the functionalized material by conventional techniques such as contact angle and FTIR showed a change of the properties of porous structures in line with the expected surface modifications. However, these techniques do not permit to clearly distinguish between internally and externally grafted functional groups. For this reason, an innovative procedure based on angle-resolved XPS was set-up and applied to differently functionalized pSi layers. By this technique, we obtained indications of prevalent grafting of hydrophilic moieties on the external surface and hydrophobic ones inside the pores.

We report on the α-sexithiophene sub-monolayer growth with supersonic molecular beam deposition by investigating how the kinetic energy of the impinging molecules influences the growth on substrates with different surface wettabilities and temperatures. The results show that the energy of the impinging molecules affects the morphology of the molecular film increasing the coverage and the island size, and reducing the fractality of the sub-monolayer islands. The possibility of directing growth of more ordered islands could improve the performances of electronic devices, which are greatly affected by the structure of the first monolayers.

Porous silicon solid supports with pore diameter 0.5–1 μm, infiltrated with Ag nanostructures for surface enhanced Raman scattering (SERS) were prepared according to two procedures: spontaneous Ag+ reduction on the surface of freshly etched porous silicon immersed in Ag+ aqueous solutions, or anchoring colloidal Ag nanoparticles on the surface previously functionalized by aminosilane. Using Rhodamine 6G (RH6G) as analyte the detection limits were of the order of 20 μM and 20 nM with porous silicon metalized by the first and second procedure, respectively. This large increase of sensitivity notwithstanding a reduced surface density of Rhodamine 6G obtained on porous silicon metalized by the second procedure is discussed in terms of better hot spot efficiency and reduced aspecific binding out of the hot regions obtained depositing the colloids on the aminosilane functionalized surface.

Polymer pyrolysis to nanoceramics is employed for the production of photo-luminescent thin film samples, consisting of Si-nanocrystals dispersed in silica matrix. Thin films were deposited on Si wafer by spin-coating technique from a triethoxysilane-derived sol–gel solution. This is a fast process and a low cost technique. Samples were annealed at different temperatures between 600 °C and 1300 °C, under N 2 gas atmosphere. Structural evolution and luminescence from Si-ncs vs. temperature were investigated by FT-IR absorption spectroscopy and photo-luminescence. Absorption spectrum of As-Prep sample shows several vibrational bands due to Si–H, C–H x , and Si–O–Si structural units, without any appreciable luminescence. Silica phase segregation and intense PL (790 nm) due to Si-ncs were observed on annealing at T > 1000 °C.

Silicon oxycarbide samples were prepared by polymer pyrolysis using a methyltriethoxysilane-derived precursor. Transparent crack-free gel samples were obtained from the alkoxide by the sol–gel process. The dried gel samples were pyrolysed at different temperatures in the range between 400 and 1500 °C in Ar atmosphere. The chemical and microstructural evolution during pyrolysis were followed by FT-IR absorption, Raman scattering and photoluminescence (PL). The FT-IR spectra show the change in Si–O–Si asymmetric stretching, C–H x , Si–CH 3 stretching vibrational bands. The peak position and shape of these bands were found stable up to 600 °C. Above this temperature, a remarkable change in shape and peak position of Si–O–Si related vibration, reduction in C–H x and Si–CH 3 stretching absorption bands have been observed. Degradation of Si–CH 3 and the simultaneous formation of Si–CH 2 –Si via Si–CH 2 –CH 2 –Si is explicitly observed, experimentally. Annealing the sample at 800 °C starts to show the clear presence of D and G bands, related to the free carbon precipitation and its segregation with the temperature. The broad PL spectra centered at around 670 nm for the samples pyrolysed at 1500 °C shows an important information regarding the presence of crystalline SiC.