Direct electrochemiluminescent immunosensing for an early indication of coronary heart disease using dual biomarkers

Efficient Electrochemiluminescence Sensing in Microfluidic Biosensors: A Review

Microfluidic devices are capable of handling 10-9 L to 10-18 L of fluids by incorporating tiny channels with dimensions of ten to hundreds of micrometers, and they can be fabricated using a wide range of materials including glass, silicon, polymers, paper, and cloth for tailored sensing applications. Microfluidic biosensors integrated with detection methods such as electrochemiluminescence (ECL) can be used for the diagnosis and prognosis of diseases. Coupled with ECL, these tandem devices are capable of sensing biomarkers at nanomolar to picomolar concentrations, reproducibly. Measurement at this low level of concentration makes microfluidic electrochemiluminescence (MF-ECL) devices ideal for biomarker detection in the context of early warning systems for diseases such as myocardial infarction, cancer, and others. However, the technology relies on the nature and inherent characteristics of an efficient luminophore. The luminophore typically undergoes a redox process to generate excited species which emit energy in the form of light upon relaxation to lower energy states. Therefore, in biosensor design the efficiency of the luminophore is critical. This review is focused on the integration of microfluidic devices with biosensors and using electrochemiluminescence as a detection method. We highlight the dual role of carbon quantum dots as a luminophore and co-reactant in electrochemiluminescence analysis, drawing on their unique properties that include large specific surface area, easy functionalization, and unique luminescent properties.

Electrochemical sensor based on micromotor technology for detection of Ox-LDL in whole blood

Detecting the concentration of oxidized low-density lipoprotein (Ox-LDL) in whole blood is of great significance for monitoring the development of atherosclerosis. In order to simplify the complex processing steps of blood sample before the detection, an electrochemical sensor based on micromotor technology was designed, which was called magnesium (Mg)-Fe₃O₄@ prussian blue (PB)@ antibody of Ox-LDL (Ab)@ bovine serum albumin (BSA). The active capture of Ox-LDL in whole blood can be realized by the help of the movement of Mg microsphere with the driving force of H₂. Then the captured Ox-LDL was collected on the surface of the magnetic glassy carbon electrode (MGCE) by self-made funnel device, and the content of Ox-LDL was detected by electrochemical workstation in the way of chronoamperometry (i-t). Due to the application of micromotor, the electrochemical sensor proposed in this study had good detection efficiency for Ox-LDL in whole blood with range from 1 × 10^-2 μg/mL to 10 μg/mL, and the limit of detection (LOD) towards Ox-LDL was 9.80 × 10^-4 μg/mL. The electrochemical sensor based on micromotor technology provides a rapid, effective, and sensitive method for the detection of Ox-LDL in whole blood.

Recent Progress in Electrochemical Immunosensors

Biosensors used for medical diagnosis work by analyzing physiological fluids. Antibodies have been frequently used as molecular recognition molecules for the specific binding of target analytes from complex biological solutions. Electrochemistry has been introduced for the measurement of quantitative signals from transducer-bound analytes for many reasons, including good sensitivity. Recently, numerous electrochemical immunosensors have been developed and various strategies have been proposed to detect biomarkers. In this paper, the recent progress in electrochemical immunosensors is reviewed. In particular, we focused on the immobilization methods using antibodies for voltammetric, amperometric, impedimetric, and electrochemiluminescent immunosensors.