Immuno-biosensors for Carcinoma Early Detection
Date Issued
2011
Date
2011
Author(s)
Chen, Jung-Chih
Abstract
The quartz crystal microbalance (QCM) technology has reached a mature and commonly used in biomedical sensing technology. Due to this system can detect extremely low concentrations, so it can develop into an immune sensor (Immunosensor), the most commonly used for microbial detection. However, the QCM method been widely used, but few clinical examples. As our team has the experience and analysis of trace substances in biological samples of cancer clinical sensing technology, once combined with quartz crystal microbalance method, the set of efficient, sensitive, time-saving and economic ... in one.
This study attempts to modify the quartz crystal surface with biological markers (biomarkers), which is a fixed biological marker of antibody in quartz crystal surface, and using the phenomenon of antibody and antigen specific adsorption, to detect cancer tumor markers.
In the first part of the experiment, we proposes the construction of a molecular recognition layer composed of thiol molecules and further activation with EDC-NHS complexes on the surface of a quartz crystal microbalance (QCM). The use of tumor markers factor: EGFr Ag-Ab as the object of study. EGFr is usually highly expression in non-small cell lung cancer patients (the most common cancer in Western countries, which includes squamous cell carcinoma, adenocarcinoma, large cell carcinoma and bronchioloalveolar lung cancer, etc.). We use special materials: thiosalicylic acid (TSA) to modify the surface of quartz crystal, and Protein G to avoid the import of non-specific adsorption. Two different antibody immobilization patterns such as chemical cross-linking and site-specific via protein G were attempted. Accordingly, protein G mediated antibody immobilization controls the quantity and orientation of the antibody molecules on the electrode surface for its high affinity to antigens. Thus, a similar immobilization strategy was utilized for the flow-cell analysis of real-time binding of EGFr. A linear relationship was observed between the frequency shift and different EGFr concentrations (0.01–10 μg/mL), and the detection limition lower than 1 ng/mL. The stepwise assembly of the immunosensor was characterized by quartz crystal microbalance. It was also demonstrated that, the prepared sensor surface was stable enough to withstand the repeated surface regeneration with 0.1 M NaOH.
In the second part, the ability to produce indigenous diagnostic tests for neonatal meningitis, that are novel, specific yet cost-effective would now provide a huge impact on public health management in developing countries. Escherichia coli (K1) is the major cause of neonatal meningitis through the interaction with human brain microvascular endothelial cells (HBMEC). Outer membrane protein A (OmpA) is a major protein in the E. coli outer membrane. However, there are not any rapid detections for OmpA. Immobilization of antibodies onto the crystal will be allowed to detect OmpA antigens for nanomedicine applications. This study originally developed the aforementioned QCM method to rapidly detect OmpA antigen. The method utilizes the piezoelectric immunosensor onto whose thiol activated crystal surface the affinity-purified antibodies would be immobilized, and the main objective of this study is to optimize the surface monolayer conditions to provide efficient binding of anti-OmpA IgG antibody and to exploit sensing surface for the detection of OmpA antigen, as an alternative diagnostic test. Though, the frequency shift was lower for OmpA antibody, still it can able to detect lower than 20 ng/ml of OmpA antigen. The detection of OmpA protein by QCM method is comparatively simple and sensitive than other systems.
Subjects
Quartz crystal microbalance (QCM)
Immunosensor
Biomarkers
Tumor markers
non-small cell lung cancer
Epidermal growth factor receptor (EGFr)
Flow-injection Assay (FIA)
Neonatal meningitis
Outer membrane protein A (OmpA)
SDGs
Type
thesis
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