Concanavalin A-activated magnetic nanoparticles as an affine material for urinary exosome isolation.

Exosomes are a type of membrane vesicle secreted into the extracellular medium by most cell types. They have a great potential for clinical practice as noninvasive biomarkers for diagnosis of various diseases, prognosis, and monitoring of therapy, which stimulates the development of simple methods for isolating exosomes from biological fluids. A novel affine material based on aminosilanized superparamagnetic core‒shell nanoparticles for fast isolation of urinary exosomes is reported.

Luciferase NLuc Site-Specific Conjugation to Generate Reporters for In Vitro Assays.

NanoLuc (NLuc) is an artificial coelenterazine-dependent luciferase generated from the deep-sea shrimp . Its peculiar properties─small size and long-lasting bright bioluminescence triggered with the synthetic substrate furimazine─have made this enzyme popular as a reporter in a variety of analytical systems. Basically, to ensure the assay specificity, NLuc is genetically fused to the polypeptide with affinity for the corresponding target.

Ca-Triggered Coelenterazine-Binding Protein Renilla: Expected and Unexpected Features.

Ca-triggered coelenterazine-binding protein (CBP) is a natural form of the luciferase substrate involved in the Renilla bioluminescence reaction. It is a stable complex of coelenterazine and apoprotein that, unlike coelenterazine, is soluble and stable in an aquatic environment and yields a significantly higher bioluminescent signal. This makes CBP a convenient substrate for luciferase-based in vitro assay.

Starch-Coated Magnetic Iron Oxide Nanoparticles for Affinity Purification of Recombinant Proteins.

Starch-coated magnetic iron oxide nanoparticles have been synthesized by a simple, fast, and cost-effective co-precipitation method with cornstarch as a stabilizing agent. The structural and magnetic characteristics of the synthesized material have been studied by transmission electron microscopy, Mössbauer spectroscopy, and vibrating sample magnetometry. The nature of bonds between ferrihydrite nanoparticles and a starch shell has been examined by Fourier transform infrared spectroscopy.

Protein biosensor based on Schottky barrier nanowire field effect transistor.

A top-down nanofabrication approach involving molecular beam epitaxy and electron beam lithography was used to obtain silicon nanowire-based back gate field-effect transistors with Schottky contacts on silicon-on-insulator (SOI) wafers. The resulting device is applied in biomolecular detection based on the changes in the drain-source current (I). In this context, we have explained the physical mechanisms of charge carrier transport in the nanowire using energy band diagrams and numerical 2D simulations in TCAD.

Coelenterazine-Dependent Luciferases as a Powerful Analytical Tool for Research and Biomedical Applications.

The functioning of bioluminescent systems in most of the known marine organisms is based on the oxidation reaction of the same substrate-coelenterazine (CTZ), catalyzed by luciferase. Despite the diversity in structures and the functioning mechanisms, these enzymes can be united into a common group called CTZ-dependent luciferases. Among these, there are two sharply different types of the system organization-Ca-regulated photoproteins and luciferases themselves that function in accordance with the classical enzyme-substrate kinetics.

The Ca -Regulated Photoprotein Obelin as a Tool for SELEX Monitoring and DNA Aptamer Affinity Evaluation.

Bioluminescent solid-phase analysis was proposed to monitor the selection process and to determine binding characteristics of the aptamer-target complexes during design and development of the specific aptamers. The assay involves Ca -regulated photoprotein obelin as a simple, sensitive and fast reporter. Applicability and the prospects of the approach were exemplified by identification of DNA aptamers to cardiac troponin I, a highly specific early biomarker for acute myocardial infarction.

Bioluminescent aptamer-based sandwich-type assay of anti-myelin basic protein autoantibodies associated with multiple sclerosis.

Bioluminescent solid-phase sandwich-type microassay was developed to detect multiple sclerosis (MS)-associated autoantibodies in human sera. The assay is based on two different 2'-F-Py RNA aptamers against the target autoantibodies as biospecific elements, and Ca-regulated photoprotein obelin as a reporter. The paper describes elaboration of the assay and its application to 91 serum samples from patients with clinically definite MS and 86 ones from individuals healthy in terms of MS.

Bioluminescent aptamer-based solid-phase microassay to detect lung tumor cells in plasma.

Two high-affinity DNA aptamers for lung tumor cells were applied as biospecific elements in bioluminescent assay of patient blood. The oligonucleotide complementary to the 5' end of both aptamers carrying either biotin or Ca-regulated photoprotein obelin was used to form a sandwich-type analytical complex on the surfaces of magnetic streptavidin-activated microspherical particles. Clinical blood samples from cases of morphologically confirmed lung cancer and control samples were analyzed applying the developed assay.

Bioluminescent SNP genotyping technique: Development and application for detection of melanocortin 1 receptor gene polymorphisms.

SNP genotyping based on the reaction of specific primer extension with the following bioluminescent detection of its products was shown to be potentially applicable for biomedical exploration. The paper describes its elaboration and first application in extensive biomedical research concerning MC1R gene variants' frequency and associations with clinical characteristics in melanoma patients of Eastern Siberia (Krasnoyarsk region, Russia). Polymorphisms rs 1805007 (R151C), rs 1805008 (R160W), and rs 1805009 (D294H) were detected in 174 DNA samples from patients with histologically proved diagnosis of cutaneous melanoma and in 200 samples from healthy individuals.

Mutants of Ca -regulated Photoprotein Obelin for Site-specific Conjugation.

Color variants of Ca -regulated photoprotein obelin were shown to be an important tool for dual-analyte binding assay. To provide site-directed conjugation with biospecific molecules, several obelin color mutants carrying unique cysteine residues were obtained and characterized for their novel properties. A pair of obelins Y138F,A5C and W92F,H22E,D12C was found to be most suitable (in terms of high bioluminescent activity and stability) as reporters in simultaneous assay of two targets in a sample.

Hybrid Minimal Core Streptavidin-Obelin as a Versatile Reporter for Bioluminescence-based Bioassay.

Ca -regulated photoprotein obelin was genetically fused with a minimum-sized core streptavidin. Hybrid protein (SAV-OL) was produced by bacterial expression and applied as a specific bioluminescent probe in diverse solid-phase assays. The obtained results clearly demonstrate specific activity of each domain indicating its proper folding with favorable space orientation.

Simultaneous genotyping of four single nucleotide polymorphisms associated with risk factors of hemostasis disorders.

Multiplex simultaneous genotyping technique was developed for four polymorphisms in genes coding for blood coagulation factors and homocysteine metabolism which are considered as thrombophilia related mutations: FV Leiden, FII G20210A, MTHFR C677T, and FVII G10976A. It is based on primer extension reaction with the following bioluminescent solid-phase microassay. At that, two dierent in bioluminescence obelin mutants were applied to simultaneous detection of two gene allelic variants.

Application of enzyme bioluminescence for medical diagnostics.

Nowadays luciferases are effectively used as analytical instruments in a great variety of research fields. Of special interest are the studies dealing with elaboration of novel analytical systems for the purposes of medical diagnostics. The ever-expanding spectrum of clinically important analytes accounts for the increasing demand for new techniques for their detection.

RNA aptamer against autoantibodies associated with multiple sclerosis and bioluminescent detection probe on its basis.

Nowadays, there are no specific laboratory tests for establishing the diagnosis of multiple sclerosis (MS). The presence of proteolytic autoantibodies against myelin basic protein is now considered as a characteristic feature of MS. New 2'-F-containing RNA aptamer of high affinity and specificity to these antibodies was selected.

Hydrogen-bond networks between the C-terminus and Arg from the first α-helix stabilize photoprotein molecules.

Previous studies have stated that aequorin loses most of its bioluminescence activity upon modification of the C-terminus, thus limiting the production of photoprotein fusion proteins at its N-terminus. In the present work, we investigate the importance of the C-terminal proline and the hydrogen bonds it forms for photoprotein active complex formation, stability and functional activity. According to the crystal structures of obelin and aequorin, two Ca(2+)-regulated photoproteins, the carboxyl group of the C-terminal Pro forms two hydrogen bonds with the side chain of Arg21 (Arg15 in aequorin case) situated in the first α-helix.

Simultaneous bioluminescent immunoassay of serum total and IgG-bound prolactins.

Novel dual-analyte single-well bioluminescence immunoassay (BLIA) for total and IgG-bound prolactins was developed on the base of Ca(2+)-regulated photoprotein obelin mutants with altered color and kinetics of bioluminescence signal as reporters. The mutants W92F-H22E and Y138F were chemically conjugated with monoclonal mouse anti-hPRL and anti-hIgG immunoglobulins and thus displayed signals from total prolactin and IgG-bounded prolactin (macroprolactin) correspondingly. Bioluminescence of the reporters was simultaneously triggered by a single injection of Ca(2+) solution and discriminated via bioluminescent signal spectral and time resolution.