Geometrically constrained magnetic domain walls (DWs) in magnetic nanowires can be manipulated at the nanometer scale. The inhomogeneous magnetic stray field generated by a DW can capture a magnetic nanoparticle in solution. On-chip nanomanipulation of individual magnetic beads coated with proteins is demonstrated through the motion of geometrically constrained DWs in specially designed magnetic nanoconduits fully integrated in a lab-on-a-chip platform

The ability to trap, manipulate and release single cells on a surface is important both for fundamental studies of cellular processes and for the development of novel lab-on-chip miniaturized tools for biological and medical applications. In this paper we demonstrate how magnetic domain walls generated in micro- and nano-structures fabricated on a chip surface can be used to handle single yeast cells labeled with magnetic beads. In detail, first we show that the proposed approach maintains the microorganism viable, as proven by monitoring the division of labeled yeast cells trapped by domain walls over 16 hours. Moreover, we demonstrate the controlled transport and release of individual yeast cells via displacement and annihilation of individual domain walls in micro- and nano-sized magnetic structures. These results pave the way to the implementation of magnetic devices based on domain walls technology in lab-on-chip systems devoted to accurate individual cell trapping and manipulation.

The description and understanding of absorption and distribution of potential new drug compounds in the organism is of paramount importance for the successful development of new drugs. However, the currently used physical chemical parameters such as oil-water distribution coefficients and ionization constants frequently fall short when it comes to a detailed description of the highly heterogeneous environments of both lipophilic and hydrophilic characters through which the drug compound passes. In this work, a new procedure based on electrochemistry at the interface between immiscible electrolyte solutions for addressing drug compound-ligand interactions in lipophilic environments as well as nonspecific ligand effects on distribution behavior has been developed. An attractive feature of the method is that it can simultaneously provide data for oil-water partition coefficients and ionization constants. The new procedure is demonstrated using five drug compounds with different physical chemical parameters and cholesterol as the oil-phase ligand. The use of ligand shift ion partition diagrams in the data presentation allows a quick visualization and comparison of a series of related drug compounds.

The description and understanding of noncovalent interactions and distribution of potential new drug compounds in an organism is of paramount importance for the successful development of new drugs. In this work, a new procedure based on electrochemistry at the interface between two immiscible electrolyte solutions (ITIES) for addressing and discriminating between drug compound/ligand interactions in aqueous solution and nonspecific ligand effects on oil-water distribution behavior has been developed. The procedure is demonstrated using five drug compounds with different physical chemical parameters and alpha-cyclodextrin as the aqueous phase ligand. Alpha-cyclodextrin was chosen as an aqueous phase ligand, as it is frequently used in drug formulations to enhance solubility and bioavailability of drug compounds. Supplementary capillary electrophoresis experiments provided more detailed information on alpha-cyclodextrin drug complexation and, in combination with the electrochemical studies, provided information on solvation effects affecting the oil-water distribution of the drug compounds. The use of ligand shift ion partition diagrams for data presentation is a convenient format for the visualization of ligand effects on distribution behavior of related drug compounds.

Acetochlor[2-chloro-N -(ethoxymethyl)-N -(2-ethyl-6-methylphenyl)acetamide] belongs to chloroacetanilide herbicides, which have been widely introduced into the world agricultural practice [1][2][3]. Chloroacetanilide herbicides are relatively unstable in the environment and undergo degradation within six months; this is a valuable property of these herbicides. However, they can be detected in reservoirs, fish, and products of plant origin in amounts higher than maximum permissible levels as a result of their agricultural use. Acetochlor is a comparatively new pesticide; it was first registered in the United States in 1994. It has now replaced related compounds because of its better biodegradability and a relatively small carcinogenic effect. However, as well as the majority of pesticides, acetochlor is genotoxic, as was exemplified in plants, rats, and human lymphocytes [1]. Therefore, acetochlor residues should be monitored in natural samples such as water and soil.Chromatographic techniques, such as gas chromatography with atomic emission [4] or mass-spectrometric detection [5, 6], high-performance liquid chromatography with various detection techniques [7,8], and capillary electrophoresis [9] are commonly used for determining herbicides, in particular, acetochlor. These techniques are highly sensitive and accurate; however, they are also expensive and time-consuming. At the same time, it is necessary to perform simple and rapid screening in a great number of samples in order to detect herbicide-contaminated areas.Immunochemical techniques based on the specific binding of an analyte to corresponding specific antibodies are well suitable for this purpose. Enzyme immunoassay (EIA) has received the widest acceptance; the theory and practice of EIA was described in detail [10]. The use of EIA for the determination of pesticides has been reported in many reviews [11][12][13][14][15][16].EIA techniques are highly sensitive and simple; they can be performed under field conditions at the sampling site [17]. Since the 1990s, EIA has been used with increasing frequency for the screening of pesticides in natural and food samples. The current status, applicability, and prospects for the widespread use of immunochemical techniques for the determination of pesticides in the environment were considered in a review [18]. Recent data on the development and use of EIA for pesticides in Russia were published in [19][20][21].Earlier, we developed immunochemical methods for the determination of acetochlor by ELISA [22] and with the use of an immunosensor [23] or a piezosensor [24]. However, these are multistep procedures, and the time of analysis is 2 to 3 h. Moreover, ELISA includes a number of steps of pipetting and washing with the use of several specific reagents; it requires qualified personnel. Therefore, the recent trend has been toward the development of nonseparation (homogeneous) immunoassay techniques, which significantly improve socalled high-throughput screening (HTS) [25]. Although an optimum immunoassay procedure for...