The study explored possible reproductive and endocrine effects of short-term (5 days) oral exposure to anatase TiO2 nanoparticles (0, 1, 2 mg/kg body weight per day) in rat. Nanoparticles were characterised by scanning electron microscopy (SEM) and transmission electron microscopy, and their presence in spleen, a target organ for bioaccumulation, was investigated by single-particle inductively coupled plasma mass spectrometry and SEM/energy-dispersive X-ray. Analyses included serum hormone levels (testosterone, 17-β-estradiol and triiodothyronine) and histopathology of thyroid, adrenals, ovary, uterus, testis and spleen. Increased total Ti tissue levels were found in spleen and ovaries. Sex-related histological alterations were observed at both dose levels in thyroid, adrenal medulla, adrenal cortex (females) and ovarian granulosa, without general toxicity. Altered thyroid function was indicated by reduced T3 (males). Testosterone levels increased in high-dose males and decreased in females. In the spleen of treated animals TiO2 aggregates and increased white pulp (high-dose females) were detected, even though Ti tissue levels remained low reflecting the low doses and the short exposure time. Our findings prompt to comprehensively assess endocrine and reproductive effects in the safety evaluation of nanomaterials.

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Polymeric thin films have been awakening continuous and growing interest for application in nanotechnology. For such applications, the assessment of their (nano)mechanical properties is a key issue, since they may dramatically vary between the bulk and the thin film state, even for the same polymer. Therefore, techniques are required for the in situ characterization of mechanical properties of thin films that must be nondestructive or only minimally destructive. Also, they must also be able to probe nanometer-thick ultrathin films and layers and capable of imaging the mechanical properties of the sample with nanometer lateral resolution, since, for instance, at these scales blends or copolymers are not uniform, their phases being separated. Atomic force microscopy (AFM) has been proposed as a tool for the development of a number of techniques that match such requirements. In this review, we describe the state of the art of the main AFM-based methods for qualitative and quantitative single-point measurements and imaging of mechanical properties of polymeric thin films, illustrating their specific merits and limitations.

Nanotechnologies are opening up new horizons in almost all scientific and technological fields. Among these, applications of nanotechnologies are expected to bring large benefits and add value to the food and food-related industries through the whole food chain, from production to processing, safety, packaging, transportation, storage and delivery. Nanotechnology consists in the realization and manipulation of nano-sized matter, the unique properties of which with respect to their bulk counterparts are illustrated and discussed. Then, the main tools and techniques routinely used in nanotechnology for the nanoscale characterization of food matrices as well as for the analytical determination of nanomaterials in food samples are reviewed. Finally, safety and risk assessment issues are discussed and an overview of applications of nanotechnology to the food sector is provided along with a description of the current regulatory framework.

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Magnetic force microscopy (MFM) has been demonstrated as valuable technique for the characterization of magnetic nanomaterials. To be analyzed by MFM techniques, nanomaterials are generally deposited on flat substrates, resulting in an additional contrast in MFM images due to unavoidable heterogeneous electrostatic tip-sample interactions, which cannot be easily distinguished from the magnetic one. In order to correctly interpret MFM data, a method to remove the electrostatic contributions from MFM images is needed. In this work, we propose a new MFM technique, called controlled magnetization MFM (CM-MFM), based on the in situ control of the probe magnetization state, which allows the evaluation and the elimination of electrostatic contribution in MFM images. The effectiveness of the technique is demonstrated through a challenging case study, i.e., the analysis of superparamagnetic nanoparticles in absence of applied external magnetic field. Our CM-MFM technique allowed us to acquire magnetic images depurated of the electrostatic contributions, which revealed that the magnetic field generated by the tip is sufficient to completely orient the superparamagnetic nanoparticles and that the magnetic tip-sample interaction is describable through simple models once the electrostatic artifacts are removed.

Atomic force acoustic microscopy (AFAM) is a dynamical AFM-based technique very promising for nondestructive analysis of local elastic properties of materials. AFAM technique represents a powerful investigation tool in order to retrieve quantitative evaluations of the mechanical parameters, even at nanoscale. The quantitative determination of elastic properties by AFAM technique is strongly influenced by a number of experimental parameters that, at present, are not fully under control. One of such issues is that the quantitative evaluation require the knowledge of the tip geometry effectively contacting the surface during the measurements. We present and discuss an experimental approach able to determine, at first, tip geometry from contact stiffness measurements and, on the basis of the achieved information, to measure sample indentation modulus. The reliability and the accuracy of the technique has been successfully tested on samples (Si, GaAs, and InP) with very well known structural and morphological properties and with indentation modulus widely reported in literature. (c) 2005 American Institute of Physics