Although uptake into cells is highly complex and regulated, heterogeneous particle collectives are usually employed to deliver small interfering RNA (siRNA) to cells. Within these collectives, it is difficult to accurately identify the active species, and a decrease in efficacy is inherent to such preparations. Here, we demonstrate the manufacture of uniform nanoparticles with the deposition of siRNA on gold in a layer-by-layer approach, and we further report on the cellular delivery and siRNA activity as functions of surface properties.

Because nanoparticles are finding uses in myriad biomedical applications, including the delivery of nucleic acids, a detailed knowledge of their interaction with the biological system is of utmost importance. Here the size-dependent uptake of gold nanoparticles (AuNPs) (20, 30, 50 and 80 nm), coated with a layer-by-layer approach with nucleic acid and poly(ethylene imine) (PEI), into a variety of mammalian cell lines is studied. In contrast to other studies, the optimal particle diameter for cellular uptake is determined but also the number of therapeutic cargo molecules per cell. It is found that 20 nm AuNPs, with diameters of about 32 nm after the coating process and about 88 nm including the protein corona after incubation in cell culture medium, yield the highest number of nanoparticles and therapeutic DNA molecules per cell. Interestingly, PEI, which is known for its toxicity, can be applied at significantly higher concentrations than its IC(50) value, most likely because it is tightly bound to the AuNP surface and/or covered by a protein corona. These results are important for the future design of nanomaterials for the delivery of nucleic acids in two ways. They demonstrate that changes in the nanoparticle size can lead to significant differences in the number of therapeutic molecules delivered per cell, and they reveal that the toxicity of polyelectrolytes can be modulated by an appropriate binding to the nanoparticle surface.

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In this work, the dye-sensitization approach was used to optimize the compact layer/perovskite interface in planar perovskite solar cells (PSCs). The chemisorption of the triphenylamine-based metal-free organic (E)-3-(5-(4-(bis(2′,4′-dibutoxy-[1,1′-biphenyl]-4yl)amino)phenyl)thiophen-2-yl)-2-cyanoacrylic acid (D35) sensitizer via a bidentate anchor group on the titania surface resulted in both enhanced electron transfer and controlled growth of the top MAPbI 3 perovskite layer. This modification led to planar PSC devices presenting significantly improved performance and increased stability. Using the Spiro-OMeTAD molecular hole conductor, stabilized output power conversion efficiencies (PCEs) of 13% were obtained for cells with titania sensitization, clearly outperforming those of cells without D35. This investigation gives new insights into how the molecular engineering via dye sensitization of the functional interfaces affects the performance in PSCs.

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Perovskite solar cells (PSCs) are in the forefront of third-generation of photovoltaics and gained a lot of attention as a very promising green technology toward direct solar energy conversion to electricity. PSCs are fabricated following solution-processed techniques at low temperature and they present high power conversion efficiency exceeding 25%, enabling them to be attractive alternative to the silicon-based devices. This research work proposes an efficient and cost-effective photovoltaic (PV) pumping system based on PSCs. For this purpose, lab-scale PSCs were fabricated and their characteristics were determined. In parallel, the geometry of a synchronous reluctance motor (SynRM) driving a 350 m 3 /day water pump was optimized for maximizing the output power, while minimizing the torque ripple simultaneously. In addition, a perovskite solar array feeding the SynRM via an inverter was designed and implemented. The inverter was properly regulated by a control system which optimized the maximum available power of the PSCs solar array and the SynRM characteristics. Finally, laboratory measurements were performed, including a power generator simulating the behavior of the PSCs array feeding the SynRM. The obtained results confirmed the experimental validation of the proposed approach.

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