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Investigation of the mechanical properties of materials at the nanoscale is often performed by atomic force microscopy nanoindentation. However, substrates with large surface roughness and heterogeneity demand careful data analysis. This requirement is even more stringent when surface indentations with a typical depth of a few nanometers are produced to test material hardness. Accordingly, we developed a geometrical model of the nanoindenter, which was first validated by measurements on a reference gold sample. Then we used this technique to investigate the mechanical properties of a coating layer made of Balinit C, a commercially available alloy with superior anti-wear features deposited on steel. The reported results support the feasibility of reliable hardness measurements with truly nanosized indents.

Significant efforts are being devoted to develop nanotechnology for drug delivery, mainly because of the distinct advantages offered by nanometer-size polymeric systems. Moreover, targeted drug delivery can be obtained by polymer conjugation to biospecific ligands. The present investigation was aimed mainly at determining the targeting ability of hybrid nanoparticles based on synthetic polymer/protein hybrid matrices. These nanoparticles were designed for liver targeted release of proteic drugs with antiviral activity, such as alpha-interferon. Human serum albumin and the monoesters of alternating copolymers of maleic anhydride/alkyl vinyl ethers of oligo(ethylene glycol) were selected as proteic and synthetic components, respectively. Digalactosyl diacyl glycerol, a natural glycolipid selectively recognized by the asialofetuin receptor present on liver hepatocytes was used as active targeting agent. Nanoparticles of 100-300 nm average size were obtained by controlled coprecipitation method. Investigation of nanoparticle surface properties by spectroscopic analysis and by biological tests indicated that the synthesized nanoparticles do expose on their surface targeting moieties that selectively interact with liver hepatocytes receptors.