We present a multiplex microarray-based assay of DNA fragments, which allows the detection of less than 10000 DNA fragments in a sample of 100 μL (corresponding to ∼0.1 fM analyte concentration) in less than 5 min. High speed and sensitivity are due to three main features of the assay. First, biotinylated adapter oligonucleotides are hybridized to the DNA fragment. Second, it is electrophoretically concentrated from the sample onto the microarray. Third, biotin labels are detected by scanning the microarray surface with streptavidin-coated magnetic beads. Prior to analysis, dsDNA fragments and genomic DNA samples were first denatured and then annealed in the presence of blocking oligonucleotides, generating ssDNA fragments capable of hybridizing with oligonucleotide probes on the microarray. The multiplexity of the assay system was demonstrated by the simultaneous detection of the genomic DNAs of three microorganisms: E. coli, B. cereus, and M. neoaurum.

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Among the key issues that are commonly associated with the development of microarray-based assays are nonspecific binding and diffusion constraints. Here we present a novel strategy addressing both of these challenges simultaneously. The essence of the method consists in blocking the microarray surface with a blocking agent containing a perfluoroalkyl chain and a disulfide linker. The resulting surface is hydrophobic, and no immiscible liquid layer remains on it upon cyclically draining and replenishing the sample solution, ensuring an efficient mass transfer of an analyte onto a microarray. Prior to the signal detection procedure, disulfide bonds are chemically cleaved, and the perfluoroalkyl chains are removed from the microarray surface along with nonspecifically adsorbed proteins, resulting in extremely low background. Using conventional fluorescent detection, we show a 30-fold increase in signal/background ratio compared to a common epoxy-modified glass substrate. The combination of this technique with magnetic beads detection results in a simple and ultrasensitive cholera toxin (CT) immunoassay. The limit of detection (LOD) is 1 fM, which is achieved with an analyte binding time of 1 h. Efficient mass transfer provides highly sensitive detection of whole virus particles despite their low diffusion coefficient. The achieved LOD for vaccinia virus is 10 4 particles in 1 mL of sample. Finally, we have performed for the first time the simultaneous detection of whole virus and CT protein biomarker in a single assay. The developed technique can be used for multiplex detection of trace amounts of pathogens of various natures.

The article describes the problem of registration of human movement on the object and protection of the object against unauthorized access. Global Positioning System which is well proven in open field has low precision within the premises. Due to the rapid development of Wi-Fi technology and the need to organize monitoring of human motion in the protected premises, there is being developed a new approach to registering a person on site using Wi-Fi. The problem of registering unauthorized access to the object by means of Wi-Fi radio network has been considered, its strengths and weaknesses have been studied. Most organizations actively use corporative and public Wi-Fi networks and beneficially apply this well-developed infrastructure for detecting the human presence in the premises and determining their position. It has been stated that using Wi-Fi network is more profitable than installing a special access control system. The aim of the research is to develop a human motion registering system at the site protected without using a Wi-Fi-module. There have been presented experiment results of registering human motion by means of the well-developed Wi-Fi infrastructure, the experiments being conducted to analyze changes of a signal level at different positions of a single person or a number of persons in the premises. It has been inferred that the level of Wi-Fi signal changes when a person or a group of persons are present in the room, even if they don’t have a Wi-Fi-module; this fact helps register the human motion in the protected premises.