Lightsheet-based flow cytometer for whole blood with the ability for the magnetic retrieval of objects from the blood flow

Detection and extraction of circulating tumor cells and other rare objects in the bloodstream are of great interest for modern diagnostics, but devices that can solve this problem for the whole blood volume of laboratory animals are still rare. Here we have developed SPIM-based lightsheet flow cytometer for the detection of fluorescently-labeled objects in whole blood. The bypass channel between two blood vessels connected with the external flow cell was used to visualize, detect, and magnetically separate fluorescently-labeled objects without hydrodynamic focusing. Carriers for targeted drug delivery were used as model objects to test the device performance. They were injected into the bloodstream of the rat, detected fluorescently, and then captured from the bloodstream by a magnetic separator prior to filtration in organs. Carriers extracted from the whole blood were studied by a number of in vitro methods

Peculiarities of stable oscillations of high amplitude current occuring in long high-impedance planar-epitaxial gallium-arsenide-based structures

The results of experimental investigation for determining the effect of different factors (distance between contacts, type of contacts, and the grade of virgin wafers) on the origination of stable oscillations of high amplitude current in long planar-epitaxial structures based on high-impedance semi-isolating n-type gallium arsenide have been presented. It was found out that the distance between the anode and cathode contacts was a key factor determining the emergence of stable oscillations of high amplitude current in such structures

Direct determination of hydrazine, methylhydrazine, and 1,1-dimethylhydrazine by zwitterionic hydrophilic interaction liquid chromatography with amperometric detection

<p>A promising alternative to ion-chromatographic methods currently used for the direct determination of hydrazines is provided by hydrophilic interaction liquid chromatography (HILIC). In this work, we propose a method for the simultaneous determination of hydrazine, methylhydrazine and 1,1-dimethylhydrazine in natural waters and soils based on a combination of chromatographic separation on a zwitterionic sulfobetaine stationary phase (Nucleodur HILIC) in the HILIC mode with amperometric detection.</p> <p>Effects of different factors on the retention of analytes were studied and the optimum conditions of analysis were found. We recommend a mixture of acetonitrile with an aqueous phosphate buffer solution of pH 2.5 (78:22 v/v) with an ionic strength of 20 mM as a mobile phase. Detection in the direct current mode was performed at a working electrode potential of 1.1 V.</p> <p>The advantages of the method are the high efficiency of separation, rapidity, high sensitivity and a wide dynamic range of analyte concentrations, covering four orders of magnitude. The attained LOD values for analytes lie in the range 0.07–0.13 μg L^–1, which is two orders of magnitude lower than those in currently used methods of ion chromatography with electrochemical and mass spectrometric detection.</p> <p>The method was validated on samples of natural waters of different origin using the added–found technique. It was found that the error of analysis did not exceed 10% for river and ground waters and increased to 20–30% for peat bog surface waters.</p> <p>The possibility of application of the developed method to the analysis of soils was shown on samples of peat bog soils selected at places of impact of the first steps of carrier rockets and polluted by rocket fuel based on 1,1-dimethylhydrazine.</p

The Influence of Magnetic Composite Capsule Structure and Size on Their Trapping Efficiency in the Flow

A promising approach to targeted drug delivery is the remote control of magnetically sensitive objects using an external magnetic field source. This method can assist in the accumulation of magnetic carriers in the affected area for local drug delivery, thus providing magnetic nanoparticles for MRI contrast and magnetic hyperthermia, as well as the magnetic separation of objects of interest from the bloodstream and liquid biopsy samples. The possibility of magnetic objects&rsquo; capture in the flow is determined by the ratio of the magnetic field strength and the force of viscous resistance. Thus, the capturing ability is limited by the objects&rsquo; magnetic properties, size, and flow rate. Despite the importance of a thorough investigation of this process to prove the concept of magnetically controlled drug delivery, it has not been sufficiently investigated. Here, we studied the efficiency of polyelectrolyte capsules&rsquo; capture by the external magnetic field source depending on their size, the magnetic nanoparticle payload, and the suspension&rsquo;s flow rate. Additionally, we estimated the possibility of magnetically trapping cells containing magnetic capsules in flow and evaluated cells&rsquo; membrane integrity after that. These results are required to prove the possibility of the magnetically controlled delivery of the encapsulated medicine to the affected area with its subsequent retention, as well as the capability to capture magnetically labeled cells in flow