In the last decade, smart materials have been developed in the fields of optical machines, sensors, motors, robots, and energy harvesting. This is due to their capability to respond to external stimuli or environmental changes. Among smart materials, photo-mobile polymers (PMPs) based on liquid crystals are the most promising in the field of photo-responsive actuators. These polymers are made with a mixture of liquid crystals containing azobenzene moieties that can undergo photoisomerization from trans to cis under UV light. This process leads to a macroscopic bending of the PMPs, which transforms light into mechanical energy. To enhance the PMPs' actuation, a novel liquid crystal nanocomposite is proposed. In our work, the nanocomposites are prepared with different concentrations of ZnO nanoparticles (NPs) embedded in the cross-linked polymer matrix. We have demonstrated that ZnO NPs improve the actuation and mechanical properties of the PMP, and the main aim of this assay is to optimize such effect as a function of the nanoparticles concentration. We also show the lowest and highest amounts of ZnO needed to enhance the bending behavior of the PMP. Optical, mechanical, and thermal analyses were performed to characterize the PMPs. Spectral characterization in UV/vis range of the bare and doped films, optical and atomic force microscopy, were used to comprehend the role of ZnO nanoparticles and their distribution among the liquid crystals. To study the dynamic response of the PMPs and their mechanical properties, lasers at different wavelengths were used.
Nano graphene-based materials offer interesting physicochemical and biological properties for biotechnological applications due to their small size, large surface area and ability to interact with cells/tissues. Among carbon-based nanomaterials, graphene oxide is one of the most used in biological field. There is an increasing interest in shedding light on the interaction mechanisms of nanographene oxide (nGO) with cells. In fact, the effects on human health of GO, and its toxicological profile, are still largely unknown. Here we show that, by minimizing the oxidation degree of GO, its toxicity is significantly reduced in NIH 3T3 cells. Moreover, we show that mild oxidation of graphene nanoplatelets produces nGO particles, which are massively internalized into the cell cytoplasm. MTT(3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay was performed to analyze cell viability. Transmission electron microscopy (TEM) analysis was performed to evaluate nGO internalization mechanism into the cytoplasm under different oxidation degree and concentrations. For the first time, we evaluated quantitatively, the cell volume variation after nGO internalization in live fibroblasts through a label-free digital holography (DH) imaging technique and in quasi-real-time modality, thus avoiding the time-consuming and detrimental procedures usually employed by electron-based microscopy. In conclusion, here we have demonstrated that DH can be a viable tool to visualize and display 3D distributions of nano graphene oxide (nGO) uptake by fibroblast cells. DH opens the route for high-throughput investigation at single cell level for understanding how in different conditions nanoparticles aggregates distribute inside the cells.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.