A Tactile Sensor Device Exploiting the Tunable Sensitivity of Copper-PDMS Piezoresistive Composite

Abstract A low cost and highly mechanically flexible 8x8 pressure matrix sensor with dedicated electronics has been fabricated with an innovative metal-elastomer composite material. Under the action of a compressive stress the material exhibits a giant piezoresistive effect varying its electrical resistance of several orders of magnitude. This phenomenon can be tuned by changing the material composition parameters, directly modifying the sensitivity of the sensor. The micro casting fabrication technique, used for the preparation of self standing sheet of functional material, gives the possibility of easily fabricating complex-shaped structure suitable for integration on robot surface for tactile sensing. The sensor has been tested with a customized electronic circuit after an exhaustive characterization of the functional properties of the material

Lead-free piezoelectrics: V3+ to V5+ ion conversion promoting the performances of V-doped Zinc Oxide

Vanadium doped ZnO (VZO) thin films were grown by RF magnetron sputtering, starting from a ZnO:V ceramic target. The crystal structure, chemical composition, electric and piezoelectric properties of the films were investigated either on the as-grown thin films or after a post-deposition rapid thermal annealing (RTA) treatment performed at 600 °C for different lengths of time (1 and 5 min) in an oxygen atmosphere. Substitutional doping of Zn2+ with V3+ and V5+ ions strongly deteriorated the hexagonal wurtzite ZnO structure of the as-grown thin films due to lattice distortion. The resulting slight amorphization led to a poor piezoelectric response and higher resistivity. After the RTA treatment, strong c-axis oriented VZO thin films were obtained, together with a partial conversion of the starting V3+ ions into V5+. The improvement of the crystal structure and the stronger polarity of both V3+ – O and V5+ – O chemical bonds, together with the corresponding easier rotation under the application of an external electric field, positively affected the piezoelectric response and increased conductivity. This was confirmed by closed-loop butterfly piezoelectric curves, by a maximum d33 piezoelectric coefficient of 85 pm·V−1, and also by ferroelectric switching domains with a well-defined polarization hysteresis curve, featuring a residual polarization of 12.5 μC∙cm−2

The shielding effect of phospholipidic bilayers on zinc oxide nanocrystals for biomedical applications

Zinc oxide nanocrystals (ZnO NCs), thanks to their unique properties, are receiving much attention for their use in nanomedicine, in particular for therapy against cancer [1]. To be efficiently employed as diagnostic and therapeutic (yet theranostic) tools [2], highly dispersed, stable and non-toxic nanoparticles are required. In the case of ZnO NCs, there is still a lack of knowledge about cytotoxicity mechanisms and stability in the biological context, as well as immunological response and haemocompatible features. Most of these above-mentioned behaviours strongly depends on physico-chemical and surface properties of the nanoparticles. We thus propose a novel approach to stabilize the ZnO NCs in various biological media, focusing on NC aggregation and biodegradation as a function of the surface functionalization. We synthesized bare ZnO NCs, amino-propyl functionalized ones, and lipid bilayer-shielded NCs, and we characterized their morphological, chemical and physical properties. The stability behavior of the three different samples was evaluated, comparing their biodegradation profiles in different media, i.e. organic solvents, water, and different simulated and biological fluids. The studies aim to investigate how the particle surface functionalizations, and thus chemistry and charge, could influence their hydrodynamic size, zeta potential and consequent aggregation and degradation in the different solvents. We demonstrated that bare and amino-functionalized ZnO NCs strongly and rapidly aggregate when suspended in both simulated and biological media. Long-term biodegradation analysis showed small dissolution into potentially cytotoxic Zn-cations, also slightly affecting their crystalline structure. In contrast, high colloidal stability and integrity was retained for lipid-shielded ZnO NCs in all media, rendering them the ideal candidates for further theranostic applications [3]. [1] P. Zhu, Z. Weng, X. Li, X. Liu, S. Wu Adv. Mater. Interfaces 3 (2016) 1500494. [2] E. Lim, T. Kim, S. Paik, S. Haam, Y. Huh, and K. Lee, Chem. Rev. 115 (2015) 327−394. [3] B. Dumontel, M. Canta, H. Engelke, A. Chiodoni, L. Racca, A. Ancona, T. Limongi, G. Canavese and V. Cauda, J. Mater. Chem. B, under review The support from ERC Starting Grant – Project N. 678151 “Trojananohorse” and Compagnia di Sanpaolo are gratefully acknowledged

Biomimetic Non-Immunogenic Nanoassembly for the Antitumor Therapy

Nanoassembly (1) for inducing apoptosis in cancer cells comprising: a core (2) comprising at least a nanoparticle of a nano structured and semiconductor metal oxide, said nanoparticle being monocrystalline or polycrystalline; a shell (3) formed by a double phospholipid layer and proteins derived from an extracellular biovesicole chosen between an exosome, an ectosome, a connectosome, an oncosome and an apoptotic body, and an oncosome, said core (2) being enclosed inside said shell (3); and a plurality of targeting molecules (4, 4', 4") of said cancer cells, preferably monoclonal antibodies (4, 4', 4"), said molecules (4, 4', 4") being anchored to the external surface of said biovesicole

Focalization performance study of a novel bulk acoustic wave device

This work illustrates focalization performances of a silicon‐based bulk acoustic wave device applied for the separation of specimens owing to micrometric dimensions. Samples are separated in the microfluidic channel by the presence of an acoustic field, which focalizes particles or cells according to their mechanical properties compared to the surrounded medium ones. Design and fabrication processes are reported, followed by focalization performance tests conducted either with synthetic particles or cells. High focalization performances occurred at different microparticle concentrations. In addition, preliminary tests carried out with HL‐60 cells highlighted an optimal separation performance at a high flow rate and when cells are mixed with micro and nanoparticles without affecting device focalization capabilities. These encouraging results showed how this bulk acoustic wave device could be exploited to develop a diagnostic tool for early diagnosis or some specific target therapies by separating different kinds of cells or biomarkers possessing different mechanical properties such as shapes, sizes and densities

Enhanced Biostability and Cellular Uptake of Zinc Oxide Nanocrystals Shielded with Phospholipid Bilayer

The widespread use of ZnO nanomaterials for biomedical applications, including therapeutic drug delivery or stimuli-responsive activation, as well as imaging, imposes a careful control over the colloidal stability and long-term behaviour of ZnO in biological media. Moreover, the effect of ZnO nanostructures on living cells, in particular cancer cells, is still under debate. This paper discusses the role of surface chemistry and charge of zinc oxide nanocrystals, of around 15 nm in size, which influence their behaviour in biological fluids and effect on cancer cells. In particular, we address this problem by modifying the surface of pristine ZnO nanocrystals (NCs), rich of hydroxyl groups, with positively charged amino-propyl chains or, more innovatively, by self-assembling a double-lipidic membrane, shielding the ZnO NCs. Our findings show that the prolonged immersion in simulated human plasma and in the cell culture medium leads to highly colloidally dispersed ZnO NCs only when coated by the lipidic bilayer. In contrast, the pristine and amine-functionalized NCs form huge aggregates after already one hour of immersion. Partial dissolution of these two samples into potentially cytotoxic Zn2+ cations takes place, together with the precipitation of phosphate and carbonate salts on the NCs’ surface. When exposed to living HeLa cancer cells, higher amounts of lipid-shielded ZnO NCs are internalized with respect to the other samples, thus showing a reduced cytotoxicity, based on the same amount of internalized NCs. These results pave the way for the development of novel theranostic platforms based on ZnO NCs. The new formulation of ZnO shielded with a lipid-bilayer will prevent strong aggregation and premature degradation into toxic by-products, and promote a highly efficient cell uptake for further therapeutic or diagnostic functions

Mucinous breast cancer: A narrative review of the literature and a retrospective tertiary single-centre analysis

We reviewed literature and our data to find out mucinous breast cancer's overall survival (OS), disease free survival (DFS) and if there are differences between pure mucinous breast cancer and mixed mucinous breast cancer in terms of OS and DFS