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Immune Systems, Molecular Diagnostics, and Bionanotechnology
Published in Anil Kumar Anal, Bionanotechnology, 2018
Antigen–antibody interaction occurs between the epitope, small restrict particles on the surface of antigens and paratope, which is the site on the antibody where the antigen binds. Antibodies synthesized against antigens can identify surface epitopes, which represent conformational structures. On account of this ability, antibodies exhibit specificity, and therefore can differentiate between two closely related antigens or can bind to divergent antigens with similar epitopes (cross-reactivity) (Schroeder and Cavacini 2010).
β-Agonist in the environmental waters: a review on threats and determination methods
Published in Green Chemistry Letters and Reviews, 2022
Usman Armaya’u, Marinah Mohd Ariffin, Saw Hong Loh, Wan Mohd Afiq Wan Mohd Khalik, Hanis Mohd Yusoff
Liu group (80) developed an enzyme-linked immunosorbent assay (ELISA) method, aimed at detecting salbutamol in environmental water, with good sensitivity results through the inhibition at half-maximal concentrations (IC50) as the most commonly insightful indicator of a drug’s effectiveness and (limit of detection (LOD (IC50)) values of 0.466 and 0.0021 µg/L, correspondingly. This value indicates that the method managed to detect salbutamol at five times lower than the MRL value. The recoveries of 80.1-115.6% and relative standard deviation of 2.2-8.6% obtained were well within residue detection criteria. Also, the findings correlated well with the results of HPLC with a coefficient of determination of 0.988. This method was recently improved by the same group by adapting a TRFIA previously established for both salbutamol and clenbuterol in swine water (63), their latest attempt was targeting salbutamol in environmental water. The method which utilized lanthanide ions as fluorescent markers have gained a highly sensitive result having a LOD (IC50) value of 0.66 ng/L and it was claimed to have demonstrated a simpler and more stable reproducibility as compared to the immuno-PCR that uses an approach that combines the benefits of ELISA and that of the polymerase chain reaction, employed to ‘visualize’ antigen–antibody interaction (81).
Single-layer graphene-based surface plasmon resonance sensor with dynamic evanescent field enhancement for biomarker study
Published in Journal of Modern Optics, 2020
Ying Xu, Zhe Zhang, Ru-meng Yi, Xiang-dong Guo, Zhi-mei Qi
For the sake of approving the mechanism of dynamic optical enhancement effect, we respectively used MATLAB and COMSOL to conduct a numerical fitting analysis of the experimental results measured by the AuNPs-enhanced sandwich immunoassay. According to the Table 1 after two rows of data, the enhancement of the antigen–antibody interaction of the AuNPs-enhanced sandwich immunoassay cause this chip to become 1.88-fold as sensitive to the resonance wavelength shift and to have the lowest antibody detection limit of 5 pg/ml, combined with the existing knowledge, the AuNPs-Ab2 conjugates caused by the change of 1.88-fold is not only by the AuNPs refractive index change of resonance wavelength redshift. It is also partly due to the strong electric field coupling between the LSPR effect of AuNPs and the SPR effect of metal biosensor film, which further intensifies the signal and shows the redshift of resonance wavelength in the spectrum.
Study on covalent coupling process and flow characteristics of antibody on the surface of immunoassay microfluidic chip
Published in Preparative Biochemistry & Biotechnology, 2022
Hao Zhong, Yong Li, Guodong Liu, Tao Xu, Yiping Suo, Zhiqiang Wang
Figure 8 shows that under the same surface modification process conditions, different flow velocities correspond to different values of the testing region fluorescence integral area. The average flow velocity was used to characterize the actual flow velocity on the chip surface, a quotient of the distance and time of the fluid flowing through a specific channel in the chip. Under the same sample volume condition (Figure 8), the fluorescence integral area of the testing region of both aldehyde and amino substrates decreased with increasing flow velocity. When the flow velocities of aldehyde and amino substrates were 0.24 mm/s and 0.19 mm/s, respectively, the integral area value of the testing-region was twice that of other experimental groups. This can be attributed to the antigen-antibody interaction on the microfluidic chip, occurring in the liquid-solid interface microchannel, satisfying the solid-phase immune reaction mechanism[21], and its reaction kinetics are significantly different from that of the liquid phase[22]. Under the same diffusion rate conditions, the time required for the solid phase immune reaction was much longer than the phase reaction. When the flow velocity was approximately 0.2 mm/s, the reactant transport was more durable. The antigen and antibody in the fluorescent region continued to combine. The fixed antibodies in the detection region captured more antigen permanently, to form more immune complexes and had enhanced fluorescence signal values. Flow velocity that was too fast led to insufficient antigen-antibody reactions, reducing the fluorescence signal intensity. Alternatively, slow velocity led to unclean flow channel scour, and easily led to high background fluorescence signals and reduced signal-to-noise ratios. This demonstrated that there was an optimal flow rate of 0.2 mm/s for the above immune flow system.