An investigation of targeted biomolecules was accomplished by combining a micro-fluxgate-based bio-sensing system and Dynabeads. The fluxgate sensor for biomolecule detection was fabricated by Micro Electro-Mechanical system technology, including thick photoresist lithography, electroplating and chemical wet etching. The magnetic core of the sensor was made of Fe-based amorphous ribbon core and three dimension solenoid coils were used as magnetic sensitive elements. The micro-fluxgate-based bio-sensing system was characterized firstly in different concentrations of Dynabeads, and a concentration as low as 100 ng/ml was detected with an external dc magnetic field in the range of 525 μT to 875 μT. Sandwich assays are performed using antibody-antigen pair combination of biotin-streptavidin on a separated Au film substrate surface with a self-assembled layer. Detection of Alpha Fetoprotein antigens with different concentrations was performed and a minimum detectable concentration of 1 pg/ml was achieved by the bio-sensing system. It is of considerable interest due to its potential application in the biomedical field based on known specific binding of target and labels.
In this work, a micro-fluxgate-based biosensor was designed for the detection of carcinoembryonic antigen (CEA) labeled by Dynabeads. The sensor with Fe-based amorphous core and three dimension solenoid coils was fabricated by Micro Electro-Mechanical system technology. Sandwich assays are performed using antibody-antigen pair combination of biotin-streptavidin assay on a separated Au film substrate surface with a self-assembled layer. With dc magnetic fields in the range of 560 μ T to 875 μ T, detection of CEAs with different concentrations was performed and a minimum detectable concentration of 1 pg/ml was achieved. Furthermore, CEA samples with different concentrations can be distinguished.
Lei Guo,Zhen Yang,Shaotao Zhi,Zhu Feng,Chong Lei,Yong Zhou
In this study, we describe an innovative micro-fluxgate immunosensor based on superparamagnetic Dynabeads for the detection of cardiac troponin T (cTnT), an important biomarker for cardiovascular diseases. The fluxgate sensor developed in this study uses a double layer of Co-based amorphous ribbons as a sensing element and three-dimensional solenoid copper coils to control the sensitive core. The system was fabricated through a standard micro-fabrication process, including thick photoresist lithography and electroplating. Superparamagnetic Dynabeads were employed as recognition tags and double polyclonal antibody pairs combined using streptavidin–biotin binding were employed to specifically capture and label the cTnT coupled with magnetic beads on a separate Au film-coated wafer via a classical sandwich immunoassay process. Series optimization of the assay parameters was performed to achieve optimal detection parameters. Under optimal conditions, the detection and quantification of cTnT was performed by sensing the magnetic signal of the cTnT-labeled Dynabeads with the micro-fluxgate sensor. The resulting biosystem successfully detected cTnT with satisfactory sensitivity, reproducibility, stability, and specificity. A minimum detectable limit of 0.01 ng mL−1 was achieved with a linearity range of 0.01–10 ng mL−1, demonstrating the high sensitivity of this novel system. In addition to the superior detection performance, the proposed sensor is convenient to manipulate, entirely lab-free, provides a quick result, and is portable. These factors suggest that this system has the potential to be applied as a point-of-care diagnostic tool for cardiovascular disease.
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