Nanopores enable label-free detection and analysis of single biomolecules. Here, we investigate DNA translocations through a novel type of plasmonic nanopore based on a gold bowtie nanoantenna with a solid-state nanopore at the plasmonic hot spot. Plasmonic excitation of the nanopore is found to influence both the sensor signal (nanopore ionic conductance blockade during DNA translocation) and the process that captures DNA into the nanopore, without affecting the duration time of the translocations. Most striking is a strong plasmon-induced enhancement of the rate of DNA translocation events in lithium chloride (LiCl, already 10-fold enhancement at a few mW of laser power). This provides a means to utilize the excellent spatiotemporal resolution of DNA interrogations with nanopores in LiCl buffers, which is known to suffer from low event rates. We propose a mechanism based on plasmon-induced local heating and thermophoresis as explanation of our observations.

Detecting small sequences of RNA in biological samples such as microRNA or viral RNA demands highly sensitive and specific methods. Here, a reconfigurable DNA origami template has been used where a chiral arrangement of gold nanorods on the structure can lead to the generation of strong circular dichroism (CD). Switching of the cross-like DNA structure is achieved by the addition of nucleic acid sequences, which arrests the structure in one of the possible chiral states by specific molecular recognition. A specific sequence can thus be detected through the resulting changes in the plasmonic CD spectrum. We show the sensitive and selective detection of a target RNA sequence from the hepatitis C virus genome. The RNA binds to a complementary sequence that is part of the lock mechanism, which leads to the formation of a defined state of the plasmonic system with a distinct optical response. With this approach, we were able to detect this specific RNA sequence at concentrations as low as 100 pm.

A wide variety of organic dyes form, under certain conditions, clusters know as J- and H-aggregates. Cyanine dyes are such a class of molecules where the spatial proximity of several dyes leads to overlapping electron orbitals and thus to the creation of a new energy landscape compared to that of the individual units. In this work, we create artificial H-aggregates of exactly two Cyanine 3 (Cy3) dyes by covalently linking them to a DNA molecule with controlled subnanometer distances. The absorption spectra of these coupled systems exhibit a blue-shifted peak, whose intensity varies depending on the distance between the dyes and the rigidity of the DNA template. Simulated vibrational resolved spectra, based on molecular orbital theory, excellently reproduce the experimentally observed features. Circular dichroism spectroscopy additionally reveals distinct signals, which indicates a chiral arrangement of the dye molecules. Molecular dynamic simulations of a Cy3-Cy3 construct including a 14-base pair DNA sequence verified chiral stacking of the dye molecules.

Elaborating efficient strategies and deepening the understanding of light transport at the nanoscale is of great importance for future designs of artificial light-harvesting assemblies and dye-based photonic circuits. In this work, we focus on studying the phenomenon of Förster resonance energy transfer (FRET) among fluorophores of the same kind (homo-FRET) and its implications for energy cascades containing two or three different dye molecules. Utilizing the spatial programmability of DNA origami, we arranged a chain of cyanine 3 (Cy3) dyes flanked at one end with a dye of lower excitation energy, cyanine 5 (Cy5), with or without an additional dye of higher excitation energy, Alexa488, at the other end. We characterized the response of our fluorophore assemblies with bulk and single-molecule spectroscopy and support our measurements by Monte Carlo modeling of energy transfer within the system. We find that, depending on the arrangement of the fluorophores, homo-FRET between the Cy3 dyes can lead to an overall enhanced energy transfer to the acceptor fluorophore. Furthermore, we systematically analyzed the homo-FRET system by addressing the fluorescence lifetime and anisotropy. Finally, we built a homo-FRET-mediated photonic wire capable of transferring energy through the homo-FRET system from the blue donor dye (Alexa488) to the red acceptor fluorophore (Cy5) across a total distance of 16 nm.

Fast and reversible modulation of ion flow through nanosized apertures is important for many nanofluidic applications, including sensing and separation systems. Here, we present the first demonstration of a reversible plasmon-controlled nanofluidic valve. We show that plasmonic nanopores (solid-state nanopores integrated with metal nanocavities) can be used as a fluidic switch upon optical excitation. We systematically investigate the effects of laser illumination of single plasmonic nanopores and experimentally demonstrate photoresistance switching where fluidic transport and ion flow are switched on or off. This is manifested as a large (∼1–2 orders of magnitude) increase in the ionic nanopore resistance and an accompanying current rectification upon illumination at high laser powers (tens of milliwatts). At lower laser powers, the resistance decreases monotonically with increasing power, followed by an abrupt transition to high resistances at a certain threshold power. A similar rapid transition, although at a lower threshold power, is observed when the power is instead swept from high to low power. This hysteretic behavior is found to be dependent on the rate of the power sweep. The photoresistance switching effect is attributed to plasmon-induced formation and growth of nanobubbles that reversibly block the ionic current through the nanopore from one side of the membrane. This explanation is corroborated by finite-element simulations of a nanobubble in the nanopore that show the switching and the rectification.

DNA self‐assembly is a powerful tool to arrange optically active components with high accuracy in a large parallel manner. A facile approach to assemble plasmonic antennas consisting of two metallic nanoparticles (40 nm) with a single colloidal quantum dot positioned at the hot spot is presented here. The design approach is based on DNA complementarity, stoichiometry, and steric hindrance principles. Since no intermediate molecules other than short DNA strands are required, the structures possess a very small gap (≈ 5 nm) which is desired to achieve high Purcell factors and plasmonic enhancement. As a proof‐of‐concept, the fluorescence emission from antennas assembled with both conventional and ultrasmooth spherical gold particles is measured. An increase in fluorescence is obtained, up to ≈30‐fold, compared to quantum dots without antenna.

Detecting small sequences of RNA in biological samples such as microRNA or viral RNA demands highly sensitive and specific methods. Here, a reconfigurable DNA origami template has been used where a chiral arrangement of gold nanorods on the structure can lead to the generation of strong circular dichroism (CD). Switching of the cross‐like DNA structure is achieved by the addition of nucleic acid sequences, which arrests the structure in one of the possible chiral states by specific molecular recognition. A specific sequence can thus be detected through the resulting changes in the plasmonic CD spectrum. We show the sensitive and selective detection of a target RNA sequence from the hepatitis C virus genome. The RNA binds to a complementary sequence that is part of the lock mechanism, which leads to the formation of a defined state of the plasmonic system with a distinct optical response. With this approach, we were able to detect this specific RNA sequence at concentrations as low as 100 pm.

For the purpose of evaluating the local heritage of eastern Numidia, an ethnobotanical survey was conducted on a population located in the province (department) of El-Tarf (North-East of Algeria) on a frequency of use of two plants known in traditional health; Eucalyptus globulus (Myrtaceae) and Rosmarinus officinalis (Lamiaceae). After processing data, our results show a female dominance when using these plants on a fairly advanced age group (40 to 60 years old). These plants are used by the people at their fresh state and deem the leaf as the most used part for therapeutic and cosmetic purposes. Furthermore, steam baths and infusion remain the most widespread preparation methods. Most consumers use these plants to treat influenza, respiratory illnesses as well as diseases of the digestive tract. GC-MS of essential oils extracted from the plants studied disclose a dominance of the alcohols portrayed by the monoterpenes (42.73%), sesquiterpenes (32.6%) and oxides (10.48%) in E. globulus. Data also indicate a high content of oxides (38.11%) monoterpene alcohols (20.43%) and monoterpenes (19.70%) in R.officinalis. Toxicological contact tests were achieved on a store-products pest Ephestia kuehniella. The test results were assessed with E.globulus (LC50=0.013; LC95=0.081 µl/cm 2 ) and R.officinalis (LC50=0.011; LC95=0.059 µl/cm 2 ). The lethal time changes according to the dose used and the tested plant. In E.globulus, we observe (concentration: 0.005 µl/cm 2 ; LT50=56.2 h), (Concentration: 0.01 µl/cm 2 ; LT50=49.53h) and (Concentration: 0.04µl/cm 2 ; LT50=20.93h). Whereas in R.officinalis, we recorded (Concentration: 0.005 µl/cm 2 ; LT50=55.7h), (Concentration: 0.01µl/cm 2; LT50=54.99 h) and (Concentration: 0.04µl/cm 2 ; LT50=29.13 h). The bioinsecticide has also been administered by fumigation and underpins toxicity by the reduction of adults longevity in E.kuehniella with R.officinalis (LC50=4.03 µl/l air; LC95=14.73 µl/l air) and E.globulus (LC50=7.76 µl/lair; LC95=21.23 µl/l air). In addition, the tested plants show an outstanding repellent effect as long as E.globulus and R.officinalis essential oils respectively demonstrate a slightly repellent power at 42.22% (RD50=0.09 µl/cm 2 ; RD95=0.24 µl/cm 2 ) and repellent at 60.00% (RD50=0.06 µl/cm 2 ; RD95= 0.35 µl/cm 2 ) towards E.kuehniella adults. The plant resources represent a genuine reserve of bioactive molecules, which can create solutions to sustainable development issues. These plants might be the source of new molecules of combat against some pests in order to protect human health and safeguard the environment.