Dendrimer enriched single-use aptasensor for impedimetric detection of activated protein C

Hybrid Impedimetric Biosensors for Express Protein Markers Detection

Impedimetric biosensors represent a powerful and promising tool for studying and monitoring biological processes associated with proteins and can contribute to the development of new approaches in the diagnosis and treatment of diseases. The basic principles, analytical methods, and applications of hybrid impedimetric biosensors for express protein detection in biological fluids are described. The advantages of this type of biosensors, such as simplicity and speed of operation, sensitivity and selectivity of analysis, cost-effectiveness, and an ability to be integrated into hybrid microfluidic systems, are demonstrated. Current challenges and development prospects in this area are analyzed. They include (a) the selection of materials for electrodes and formation of nanostructures on their surface; (b) the development of efficient methods for biorecognition elements' deposition on the electrodes' surface, providing the specificity and sensitivity of biosensing; (c) the reducing of nonspecific binding and interference, which could affect specificity; (d) adapting biosensors to real samples and conditions of operation; (e) expanding the range of detected proteins; and, finally, (f) the development of biosensor integration into large microanalytical system technologies. This review could be useful for researchers working in the field of impedimetric biosensors for protein detection, as well as for those interested in the application of this type of biosensor in biomedical diagnostics.

Carbon Nanofiber-Ionic Liquid Nanocomposite Modified Aptasensors Developed for Electrochemical Investigation of Interaction of Aptamer/Aptamer-Antisense Pair with Activated Protein C

Selective and sensitive detection of human activated protein C (APC) was performed herein by using carbon nanofiber (CNF) and ionic liquid (IL) composite modified pencil graphite electrode (PGE) and electrochemical impedance spectroscopy (EIS) technique. A carbon nanomaterial-based electrochemical aptasensor was designed and implemented for the first time in this study for the solution-phase interaction of DNA-Apt with its cognate protein APC as well as APC inhibitor aptamer-antidote pair. The applicability of this assay developed for the determination of APC in fetal bovine serum (FBS) and its selectivity against different proteins (protein C, thrombin, bovine serum albumin) was also examined. CNF-IL modified aptasensor specific to APC provided the detection limit as 0.23 μg/mL (equal to 3.83 nM) in buffer medium and 0.11 μg/mL (equal to 1.83 nM) in FBS. The duration of the proposed assay from the point of electrode modification to the detection of APC was completed within only 55 min.

Electrochemical aptasensor for activated protein C using a gold nanoparticle - Chitosan/graphene paste modified carbon paste electrode

In this work, a selective and simple electrochemical aptasensor was developed for the detection of activated protein C by employing methylene blue (MB) as a redox indicator. An activated protein C aptamer (APC-apt) was covalently immobilized on the surface of a carbon paste electrode modified with gold nanoparticle - chitosan /graphene paste (AuNPs-Chi/Gr). The AuNPs-Chi/Gr paste increased electrochemical peak current and immobilized the aptamer on the electrode surface. The process of aptasensor construction and successful immobilization of the aptamer on the electrode surface was confirmed by electrochemical cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Differential pulse voltammetry (DPV) was used to determine the methylene blue peak current. By replacing APC instead of MB at the electrode surface, the cathodic current of the MB decreases, and this decrease corresponds to the APC concentration. Under optimum conditions, the APC concentration was detected in the range from of 0.1 ng·mL^-1 to 40 μg·mL^-1 with a relatively low detection limit of 0.073 ng·mL^-1. This method was then applied to the determination of APC in human serum samples. The results revealed that this strategy can be used to measure other proteins in biological samples.

Surface plasmon resonance aptasensor for detection of human activated protein C

The aim of this study is a highly sensitive and selective label-free surface plasmon resonance (SPR) aptasensor preparation for the specific detection of human activated protein C (APC). In the first step, DNA aptamer was complexed with N-methacryloyl-L-cysteine (MAC) monomer. Then, cyanamide and 2-hydroxyethyl methacrylate solution was mixed with the DNA-Apt/MAC complex. Two different SPR sensors (Random-DNA and HEMA-MAC polymeric films) were also prepared by following the same experimental procedure. The characterization of SPR aptasensors was done by contact angle, atomic force microscopy, and ellipsometer analysis. Selectivity studies of SPR aptasensors were performed in the presence of bovine serum albumin, hemoglobin and myoglobin. Desorption studies were performed by using 0.025 M NaCl solution. The limit of detection (LOD) and limit of quantification (LOQ) values of DNA-Apt SPR aptasensor was determined as 1.5 ng/mL and 5.2 ng/mL.

Voltammetric Aptasensor Based on Magnetic Beads Assay for Detection of Human Activated Protein C

Aptamers are defined as new generation of nucleic acids, which has recently presented promising specifications over to antibodies. An increasing number of electrochemical studies related to aptamer-based sensors, so-called aptasensors have been introduced in the literature. Herein, the interaction between human activated protein C (APC) and its cognate DNA aptamer (DNA APT) was performed at the surface of magnetic beads (MBs), followed by voltammetric detection using disposable graphite electrodes (PGEs).

A novel label-free electrochemiluminescence aptasensor based on layered flowerlike molybdenum sulfide-graphene nanocomposites as matrix

A label-free and ultrasensitive electrochemiluminescence (ECL) aptasensor was constructed for the detection of thrombin. Molybdenum sulfide-graphene nanocomposites with good conductivity and large surface area were immobilized on glassy carbon electrode (GCE), and then Nafion was fixed to chemosorb the Ru(bpy)3(2+) used as luminescence agent. Subsequently, gold nanoparticles (AuNPs) were modified on the electrode to immobilize the thiol-modified thrombin aptamer for fabrication of the thrombin aptasensor. The proposed ECL aptasensor produced the ultrasensitive detection of thrombin with a low detection limit of 3.6×10(-15)M (S/N=3) and over a wide target concentration range from 1.0×10(-14) to 5.0×10(-9)M. The aptasensor has been successfully applied in the determination of thrombin in human plasma samples of both traumatic and non-traumatic injury patients, indicating its promise in biochemical analysis. The recoveries of thrombin in human plasma samples are between 88.6% and 105.0%, and the RSD values are no more than 3.7%. The results demonstrate that this aptasensor has excellent sensitivity, selectivity and stability.