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Le proprietà viscoelastiche di materiali polimerici utilizzati in applicazioni acustiche
No full textDETERMINZIONE DELLE PROPRIETÀ DEI MEZZI D'ACCOPPIAMENTO UTILLIZZATI NEL CAMPO BIOMEDICALE
No full textCharacterization of Sono-Sensitive Nanocarriers for Oxygen Delivery
Full text linkAcoustic cavitation is the physical phenomenon that leads to the formation, growth and collapse of bubbles due to the acoustic pressure variation induced by Ultrasound (US) in a liquid [1]. Over last 15 years, this phenomenon has been investigated in the nanomedicine field, with a particular attention to the development of different drug loaded nanocarriers which can be activated by US in order to release their content, or activate radicals formation process as a consequence of
cavitation.
In this study the acoustical and optical response of two different sono-sensitive nanocarrier
systems have been investigated.
The first type of nanocarriers are commercial ZnO nanoparticles (ZnO-NPs), that behave as cavitation nuclei, increasing the cavitation activity because of the presence of trapped gas pocket on their surface [2]. The seconds are perfluorocarbon based oxygen-loaded nanodroplets (OLNDs) with differing coating: polyvinyl-alcohol (PVA-OLNDs) or chitosan (Chito-OLNDs). In this case, bubbles formation arises from the acoustic droplet vaporization process induced by US and then
bubbles start oscillating up to collapse [3].
In this context, in order to obtain a metrological characterization of cavitation, a passive cavitation detector (PCD), an ecographic probe and a high-speed camera were used. The solution with the nanocarriers was led to flow into a silicone-based customized phantom and both quantitative and qualitative real-time analysis of the US response were performed.
Results show that the cavitation activity observed by means of the PCD sensor (Fig. 1a) can be correlated to the amount of bright light spots detected by the ecographic probe (Figs. 1b, 1c). Furthermore, the analysis carried out through the high-speed camera (Fig. 1e) allows to understand the dynamics of the three samples. From these results, the mean time detected to observe the cavitation event (Fig. 1d) can be evaluated, confirming the dependency on the nanocarrier structure previously observed with the PCD analysis
Multiple Approaches for Ultrasonic Cavitation Monitoring of Oxygen-Loaded Nanodroplets
Full text linkUltrasound(US) is widely used in medical field for a variety diagnostic techniques but, in recent years, it has also been creating great interest for therapeutic aims. Regarding drug delivery, the use of US as an activation source provides better spatial delivery confinement and limits the undesired side effects. However, at present there is no complete characterization at a fundamental level of the different signals produced by sono-activated nanocarriers. Therefore, the aim of this study is to obtain a metrological characterization of the cavitation phenomena induced by US through three parallel investigation approaches. US was focused into a channel of a customized phantom in which a solution with oxygen-loaded nanodroplets (OLNDs) was led to flow and the cavitation activity was monitored. Both quantitative and qualitative real-time analysis were performed giving information about the dynamics of bubble formation, oscillation and final implosion with respect to the working acoustic pressure and the type of nanodroplets, compared with pure water. From this analysis a possible interpretation of the observed results is proposed
Preparation of tunable silicon Q-dots through ultrasound
No full textSilicon quantum dots (QDs) have been prepared through ultrasound treatments of light-emitting porous
silicon layers (PSL) electrochemically etched from a p+ type crystalline silicon (c-Si). The sonication treat-
ments allowed separating the porous fraction from the bulk of c-Si as well as to mechanically reduce their
dimensions. The ultrasounds processes have been carried out in two different organic solvents (toluene
and tetrahydrofuran), and allowed obtaining silicon QDs emitting light in the blue–green part of the vis-
ible spectrum (estimated QDs diameter around 5 nm). Moreover, by adding the proper chemicals in the
solvents, such as alkenes, or simply paraffin oil, we have stabilized the QDs achieving surface modifica-
tion and observed an effect on size reduction. Photoluminescence spectra of the QDs, TEM images and a
preliminary micro-FTIR investigation of functionalised QDs will be presented in this paper
Functional mechanical attributes of natural and synthetic gel-based scaffolds in tissue engineering: strain-stiffening effects on apparent elastic modulus and compressive toughness
Full text linkThe accurate identification and determination of elastic modulus and toughness, as well as other functional mechanical attributes of artificial tissues, are of paramount importance in several fields of tissue science, tissue engineering and technology, since biomechanical and biophysical behavior is strongly linked to biological features of the medical implants and tissue-engineering scaffolds. When soft or ultra-soft materials are investigated, a relevant dispersion of elastic modulus values can be achieved, due to the strain-stiffening effects, inducing a typical non-linear behavior of these materials, as a function of strain-range. In this short communication, the Apparent elastic modulus strain-range dependence is estimated from a segmentation of the strain stiffening curve, and the related compressive toughness is investigated and discussed, based on experimental evidence, for 6 different kinds of gels, used for artificial tissue fabrication; experimental results are compared to mechanical properties of native human tissues
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