Chirality Nanosensor with Direct Electric Readout by Coupling of Nanofloret Localized Plasmons with Electronic Transport.

The detection of enantiopurity for small sample quantities is crucial, particularly in the pharmaceutical industry; however, existing methodologies rely on specific chiral recognition elements, or complex optical systems, limiting its utility. A nanoscale chirality sensor, for continuously monitoring molecular chirality using an electric circuit readout, is presented. This device design represents an alternative real-time scalable approach for chiral recognition of small quantity samples (less than 103 adsorbed molecules). The active device component relies on a gold nanofloret hybrid structure, i.e., a high aspect ratio semiconductor-metal hybrid nanosystem in which a SiGe nanowire tip is selectively decorated with a gold metallic cap. The tip mechanically touches a counter electrode to generate a nanojunction, and upon exposure to molecules, a metal-molecule-metal junction is formed. Adsorption of chiral molecules at the gold tip induces chirality in the localized plasmonic resonance at the electrode-tip junction and manifests in an enantiospecific current response.

Optical Multilevel Spin Bit Device Using Chiral Quantum Dots.

The technological advancement of data storage is reliant upon the continuous development of faster and denser memory with low power consumption. Recent progress in flash memory has focused on increasing the number of bits per cell to increase information density. In this work an optical multilevel spin bit, based on the chiral induced spin selectivity (CISS) effect, is developed using nanometer sized chiral quantum dots. A double quantum dot architecture is adsorbed on the active area of a Ni based Hall sensor and a nine-state readout is achieved.

Role of Exchange Interactions in the Magnetic Response and Intermolecular Recognition of Chiral Molecules.

The physical origin of the so-called chirality-induced spin selectivity (CISS) effect has puzzled experimental and theoretical researchers over the past few years. Early experiments were interpreted in terms of unconventional spin-orbit interactions mediated by the helical geometry. However, more recent experimental studies have clearly revealed that electronic exchange interactions also play a key role in the magnetic response of chiral molecules in singlet states. In this investigation, we use spin-polarized closed-shell density functional theory calculations to address the influence of exchange contributions to the interaction between helical molecules as well as of helical molecules with magnetized substrates. We show that exchange effects result in differences in the interaction properties with magnetized surfaces, shedding light into the possible origin of two recent important experimental results: enantiomer separation and magnetic exchange force microscopy with AFM tips functionalized with helical peptides.

Magnetic oriented microparticles preparation.

Generally speaking, reaction platforms involving ferromagnetic surfaces, with a specific magnetic direction, are limited to the two dimensional regime, due to the nature of the magnetic phenomena. Here we show a method for preparing partially coated ferromagnetic microparticles with a distinct magnetic pole. This simple preparation method was presented previously [ 1 ] to demonstrate an application for enantiomeric separation. In this method article we show;•A simple method to a-symmetrically manipulate particle surfaces.•A generic way to synchronize a bare pole of ferromagnetic microparticles.•A simple and generic enantiomer purification technique.

AFM-Based Spin-Exchange Microscopy Using Chiral Molecules.

Local magnetic imaging at nanoscale resolution is desirable for basic studies of magnetic materials and for magnetic logic and memories. However, such local imaging is hard to achieve by means of standard magnetic force microscopy. Other techniques require low temperatures, high vacuum, or strict limitations on the sample conditions. A simple and robust method is presented for locally resolved magnetic imaging based on short-range spin-exchange interactions that can be scaled down to atomic resolution. The presented method requires a conventional AFM tip functionalized with a chiral molecule. In proximity to the measured magnetic sample, charge redistribution in the chiral molecule leads to a transient spin state, caused by the chiral-induced spin-selectivity effect, followed by the exchange interaction with the imaged sample. While magnetic force microscopy imaging strongly depends on a large working distance, an accurate image is achieved using the molecular tip in proximity to the sample. The chiral molecules' spin-exchange interaction is found to be 150 meV. Using the tip with the adsorbed chiral molecules, two oppositely magnetized samples are characterized, and a magnetic imaging is performed. This method is simple to perform at room temperature and does not require high-vacuum conditions.

Broad-band high-gain room temperature photodetectors using semiconductor-metal nanofloret hybrids with wide plasmonic response.

Semiconducting nanowires are widely studied as building blocks for electro-optical devices; however, their limited cross-section and hence photo-response hinder the utilization of their full potential. Herein, we present an opto-electronic device for broad spectral detection ranging from the visible (VIS) to the short wavelength infra-red (SWIR) regime, using SiGe nanowires coupled to a broadband plasmonic antenna. The plasmonic amplification is obtained by deposition of a metallic nanotip at the edge of a nanowire utilizing a bottom-up synthesis technique. The metallic nanotip is positioned such that both optical plasmonic modes and electrical detection paths are coupled, resulting in a specific detectivity improvement of ∼1000 compared to conventional SiGe NWs. Detectivity and high gain are also measured in the SWIR regime owing to the special plasmonic response. Furthermore, the temporal response is improved by ∼1000. The fabrication process is simple and scalable, and it relies on low-resolution and facile fabrication steps with minimal requirements for top-down techniques.

Olfactory function and alternation learning in eating disorders.

Orbitofrontal dysfunction is a prominent feature of obsessive compulsive disorder (OCD). In the present study we assessed orbitofrontal functioning in eating disorders (EDs) which share many features with OCD. For this purpose we studied female adolescent inpatients with anorexia nervosa restricting type (n=40), anorexia nervosa binge/purge type (n=23), a normal weight group including patients with either bulimia nervosa or eating disorder not otherwise specified-purging type (n=33), and 20 non-ED control females. Patients were assessed at admission, and when achieving weight restoration and symptom stabilization at discharge, for depression, non-ED, and ED-related OC symptoms. Orbitofrontal functioning was assessed with an alternation learning task, and with a battery assessing olfactory threshold and discrimination. Control females were assessed once. ED patients of all subtypes performed better on olfactory threshold and discrimination, but not on alternation learning, in comparison to healthy controls. More favorable orbitofrontal functioning was associated with greater ED-related obsessionality. No changes were found in olfactory threshold and discrimination between acutely-ill and symptomatically-stabilized patients. The improvement shown in alternation learning from admission to discharge was suggested to reflect a learning effect rather than being an actual change. Our findings suggest that the better orbitofrontal functioning of ED patients in comparison to healthy controls may represent a core feature of the ED that is independent of malnutrition and deranged eating behaviors, but is associated with ED-related obsessionality.