A label-free electrochemical aptasensor for sensitive thrombin detection in whole blood

Affinity-based electrochemical sensors for biomolecular detection in whole blood

The detection and/or quantification of biomarkers in blood is important for the early detection, diagnosis, and treatment of a variety of diseases and medical conditions. Among the different types of sensors for detecting molecular biomarkers, such as proteins, nucleic acids, and small-molecule drugs, affinity-based electrochemical sensors offer the advantages of high analytical sensitivity and specificity, fast detection times, simple operation, and portability. However, biomolecular detection in whole blood is challenging due to its highly complex matrix, necessitating sample purification (i.e., centrifugation), which involves the use of bulky, expensive equipment and tedious sample-handling procedures. To address these challenges, various strategies have been employed, such as purifying the blood sample directly on the sensor, employing micro-/nanoparticles to enhance the detection signal, and coating the electrode surface with blocking agents to reduce nonspecific binding, to improve the analytical performance of affinity-based electrochemical sensors without requiring sample pre-processing steps or laboratory equipment. In this article, we present an overview of affinity-based electrochemical sensor technologies that employ these strategies for biomolecular detection in whole blood.

Nanomaterial-Based Label-Free Electrochemical Aptasensors for the Detection of Thrombin

Thrombin plays a central role in hemostasis and its imbalances in coagulation can lead to various pathologies. It is of clinical significance to develop a fast and accurate method for the quantitative detection of thrombin. Electrochemical aptasensors have the capability of combining the specific selectivity from aptamers with the extraordinary sensitivity from electrochemical techniques and thus have attracted considerable attention for the trace-level detection of thrombin. Nanomaterials and nanostructures can further enhance the performance of thrombin aptasensors to achieve high sensitivity, selectivity, and antifouling functions. In highlighting these material merits and their impacts on sensor performance, this paper reviews the most recent advances in label-free electrochemical aptasensors for thrombin detection, with an emphasis on nanomaterials and nanostructures utilized in sensor design and fabrication. The performance, advantages, and limitations of those aptasensors are summarized and compared according to their material structures and compositions.

Carbon Material Hybrid Construction on an Aptasensor for Monitoring Surgical Tumors

Carcinoembryonic antigen (CEA) is a glycoprotein, one of the common tumor biomarkers, found at low levels in body fluids. Generally, overexpression of CEA is found in various cancers, including ovarian, breast, lung, colorectal, gastric, and pancreatic cancers. Since CEA is an important tumor biomarker, the quantification of CEA is helpful for diagnosing cancer, monitoring tumor progression, and the follow-up treatment. This research develops a highly sensitive sandwich aptasensor for CEA identification on an interdigitated electrode sensor. Carbon-based material was used to attach a higher anti-CEA capture aptamer onto the sensor surface through a chemical linker, and then, CEA was quantified by the aptamer. Furthermore, CEA-spiked serum was tested by using the immobilized aptamer, which was found to not affect the target validation. The limit of detection for CEA in PBS and serum is calculated from a linear regression graph to be 0.5 ng/mL with R ² values of 0.9593 and 0.9657, respectively, over a linear range from 0.5 to 500 ng/mL. This CEA quantification by the aptasensor can help diagnose various surgical tumors and monitor their progression.

Impedance spectroscopy for identifying tau protein to monitor anesthesia-based issues

Anesthesia-related drugs cause various side effects and health-related illnesses after surgery. In particular, neurogenerative disorder is a common problem of anesthesia-related drugs. A patient gets anesthesia as a requirement of the preoperative evaluation to diagnose the medical illness, which is caused by anesthetic drug treatment. Different blood-based biomarkers help in identifying the changes appearing in patients after anesthesia treatment. Among them, tau protein is a sensitive biomarker of neurodegenerative diseases, and the fluctuations in tau proteins are highly associated with various diseases. Furthermore, researchers have found unstable levels of tau protein after the anesthesia process. The current research has focused on quantifying tau protein via impedance spectroscopy to identify the problems caused by anesthesia-related drugs. An impedance spectroscopy electrode was modified into a multiwalled carbon nanotube, and an amine-ended aptamer was then attached. This electrode surface was used to quantify the tau protein level and reached the detection limit of 1 fM. The determination coefficient was found to be y = 369.93x + 1144.9, with R² = 0.9846 in the linear range of 1 fM-1 nM. Furthermore, tau protein spiked human serum was clearly identified on the immobilized aptamer surface, indicating the specific detection.

Research progress of using micro/nanomotors in the detection and therapy of diseases related to the blood environment

Micro/nanomotors bring new possibilities for the detection and therapy of diseases related to the blood environment with their unique motion effect. This work reviews the research progress of using micro/nanomotors in the detection and therapy of diseases related to the blood environment. First, we outline the advantages of using micro/nanomotors in blood-related disease detection. To be specific, the motion capability of micro/nanomotors can increase plasma or blood fluid convection and accelerate the interaction between the sample and the capture probe. This allows the effective reduction of the amount of reagents and treatment steps. Therefore, the application of micro/nanomotors significantly improves the analytical performance. Second, we discuss the key challenges and future prospects of micro/nanomotors in the treatment of blood-environment related diseases. It is very important to design a unique treatment plan according to the etiology and specific microenvironment of the disease. The next generation of micro/nanomotors is expected to bring exciting progress to the detection and therapy of blood-environment related diseases.

Detection of four phenolic oestrogens by a novel electrochemical immunosensor based on a hexestrol monoclonal antibody

A novel HEX monoclonal antibody/MACA/nanogold electrochemical immunosensor was constructed to detect four phenolic oestrogens by a nanosized effect, layer by layer self-assembly and antigen–antibody specific immune technology.

Diagnosing human blood clotting deficiency

There are different clotting factors present in blood, carries the clotting cascade and excessive bleeding may cause a deficiency in the clotting Diagnosis of this deficiency in clotting drastically reduces the potential fatality. For enabling a sensor to detect the clotting factors, suitable probes such as antibody and aptamer have been used to capture these targets on the sensing surface. Two major clotting factors were widely studied for the diagnosis of clotting deficiency, which includes factor IX and thrombin. In addition, factor IX is considered as the substitute for heparin and the prothrombotic associated with the increased thrombin generation are taking into account their prevalence. The biosensors, surface plasmon resonance, evanescent-field-coupled waveguide-mode sensor, metal-enhanced PicoGreen fluorescence and electrochemical aptasensor were well-documented and improvements have been made for high-performance sensing. We overviewed detecting factor IX and thrombin using these biosensors, for the potential application in medical diagnosis.