Detection of human neutrophil elastase by aptamer affinity capillary electrophoresis coupled with laser-induced fluorescence using specified site fluorescently labeled aptamer

Coumarin-based turn-on fluorescence probe with a large Stokes shift for detection of endogenous neutrophil elastase in live cells and zebrafish

Neutrophil elastase (NE), a serine proteinase, is a significant biomarker which is closely related to the progress of diseases. However, only few probes have been reported for detection of NE activity and cell imaging. And these probes have exhibited small Stokes shift, which leads to high fluorescence interferences. Furthermore, only one probe among them is able to image NE in vivo successfully. To overcome the above problems, we designed a novel coumarin-based fluorescent probe HNCOU-NE with large Stokes shift to visualize NE activity in living cells and zebrafish. The new probe HNCOU-NE for NE contains fluorophore HNCOU as the reporter and pentafluoroethyl as the enzyme-active trigger moiety. As expected, HNCOU-NE displays perfect detecting performance for sensing of NE, including good water solubility, large Stokes shift, high affinity and wide linear response concentration. In addition, HNCOU-NE has been successfully utilized for NE real-time detection and imaging in different living cells, exhibiting low cytotoxicity and excellent biocompatibility. Most importantly, endogenous NE fluorescence imaging experiments reveals that HNCOU-NE can distinguish liver cancer cells (HepG2) and other cells (293T, HeLa and SKOV3), illustrating its specific ability to diagnose liver cancer cells. Besides, probe HNCOU-NE also has the ability to specifically detect endogenous NE activity in living zebrafish. All the results indicate that HNCOU-NE is a valuable probe for qualitative and quantitative sensing of NE activity in vitro and in vivo.

Aptamers for Proteins Associated with Rheumatic Diseases: Progress, Challenges, and Prospects of Diagnostic and Therapeutic Applications

Nucleic acid aptamers capable of affine and specific binding to their molecular targets have now established themselves as a very promising alternative to monoclonal antibodies for diagnostic and therapeutic applications. Although the main focus in aptamers’ research and development for biomedicine is made on cardiovascular, infectious, and malignant diseases, the use of aptamers as therapeutic or diagnostic tools in the context of rheumatic diseases is no less important. In this review, we consider the main features of aptamers that make them valuable molecular tools for rheumatologists, and summarize the studies on the selection and application of aptamers for protein biomarkers associated with rheumatic diseases. We discuss the progress in the development of aptamer-based diagnostic assays and targeted therapeutics for rheumatic disorders, future prospects in the field, and issues that have yet to be addressed.

Recent advances in computational methods for biosensor design

Biosensors are analytical tools with a great application in healthcare, food quality control, and environmental monitoring. They are of considerable interest to be designed by using cost-effective and efficient approaches. Designing biosensors with improved functionality or application in new target detection has been converted to a fast-growing field of biomedicine and biotechnology branches. Experimental efforts have led to valuable successes in the field of biosensor design; however, some deficiencies restrict their utilization for this purpose. Computational design of biosensors is introduced as a promising key to eliminate the gap. A set of reliable structure prediction of the biosensor segments, their stability, and accurate descriptors of molecular interactions are required to computationally design biosensors. In this review, we provide a comprehensive insight into the progress of computational methods to guide the design and development of biosensors, including molecular dynamics simulation, quantum mechanics calculations, molecular docking, virtual screening, and a combination of them as the hybrid methodologies. By relying on the recent advances in the computational methods, an opportunity emerged for them to be complementary or an alternative to the experimental methods in the field of biosensor design.

Paper-based human neutrophil elastase detection device for clinical wound monitoring

Paper-based diagnostic devices have been widely applied to assess the presence and status of a variety of clinical diseases by analyzing samples such as urine or blood. Due to their low cost, user-friendliness, and convenience, they have been used as point-of-care (POC) devices in countries lacking resources or energy. Despite wide-ranging research and implementation, paper-based devices have not previously been developed for wound analysis. Here, we discuss the successful development of such a tool to facilitate simple and rapid wound status assessment. The purpose of this study was to develop a paper-based elastase detection device (PEDD) for clinical wound assessment that specifically examines human neutrophil elastase (HNE), one of the most abundant serine proteases found in chronic wounds. The first step in this study was an examination of different paper substrate types (i.e., chromatography paper and filter paper) to determine which provided the best protease immobilization and colorimetric response. We then used a wax printing approach to create hydrophobic and hydrophilic regions and designated test zones created on both chromatography and filter papers. This allowed us to physically immobilize both substrate and protease within the desired test zone regions. This PEDD which demonstrated good sensitivity (0.631 μg mL^-1, in a wound fluid system) can be used to monitor protease activity expressed in wounds. After developing this device, we examined samples from 9 patients presenting a total of 7 acute and 4 chronic wounds to determine wound HNE concentration. We believe that this study may be widely applicable in both academic and commercial sciences, including the development of practical POC detection devices.

Capillary electrophoresis-based immunoassay and aptamer assay: A review

Over the last two decades, the group of techniques called affinity probe CE has been widely used for the detection and the determination of several types of biomolecules with high sensitivity. These techniques combine the low sample consumption and high separation power of CE with the selectivity of the probe to the target molecule. The assays can be defined according to the type of probe used: CE immunoassays, with an antibody as the probe, or aptamer-based CE, with an aptamer as the probe. Immunoassays are generally divided into homogeneous and heterogeneous groups, and homogeneous variant can be further performed in competitive or noncompetitive formats. Interacting partners are free in solution at homogeneous assay, as opposed to heterogeneous analyses, where one of them is immobilized onto a solid support. Highly sensitive fluorescence, chemiluminescence or electrochemical detections were typically used in this type of study. The use of the aptamers as probes has several advantages over antibodies such as shorter generation time, higher thermal stability, lower price, and lower variability. The aptamer-based CE technique was in practice utilized for the determination of proteins in biological fluids and environmentally or clinically important small molecules. Both techniques were also transferred to microchip. This review is focused on theoretical principles of these techniques and a summary of their applications in research.

Clinical and pharmaceutical applications of affinity ligands in capillary electrophoresis: A review

Affinity capillary electrophoresis (ACE) is a separation technique that combines a biologically-related binding agent with the separating power and efficiency of capillary electrophoresis. This review will examine several classes of binding agents that have been used in ACE and applications that have been described for the resulting methods in clinical or pharmaceutical analysis. Binding agents that will be considered are antibodies, aptamers, lectins, serum proteins, carbohydrates, and enzymes. This review will also describe the various formats in which each type of binding agent has been used in CE, including both homogeneous and heterogeneous methods. Specific areas of applications that will be considered are CE-based immunoassays, glycoprotein/glycan separations, chiral separations, and biointeraction studies. The general principles and formats of ACE for each of these applications will be examined, along with the potential advantages or limitations of these methods.

Affinity capillary electrophoresis for studying interactions in life sciences

Affinity capillary electrophoresis (ACE) analyzes noncovalent interactions between ligands and analytes based on changes in their electrophoretic mobility. This technique has been widely used to investigate various biomolecules, mainly proteins, polysaccharides and hormones. ACE is becoming a technique of choice to validate high throughput screening results, since it is very predictively working in realistic and relevant media, e.g. in body fluids. It is highly recommended to incorporate ACE as a powerful analytical tool to properly prepare animal testing and preclinical studies. The interacting molecules can be found free in solution or can be immobilized to a solid support. Thus, ACE is classified in two modes, free solution ACE and immobilized ACE. Every ACE mode has advantages and disadvantages. Each can be used for a variety of applications. This review covers literature of scopus and SciFinder data base in the period from 2016 until beginning 2018, including the keywords "affinity capillary electrophoresis", "immunoaffinity capillary electrophoresis", "immunoassay capillary electrophoresis" and "immunosorbent capillary electrophoresis". More than 200 articles have been found and 112 have been selected and thoroughly discussed. During this period, the data processing and the underlying calculations in mobility shift ACE (ms ACE), frontal analysis ACE (FA ACE) and plug-plug kinetic capillary electrophoresis (ppKCE) as mostly applied free solution techniques have substantially improved. The range of applications in diverse free solution and immobilized ACE techniques has been considerably broadened.