| Aim: The immunochromatography assay(ICA) is a classic point-of-care testing(POCT) technology for medical detections and diagnoses. Various multidisciplinary approaches have promoted the development of many advanced biotechnology, as well as the ICA. In the study, we aim to develop an electro-driven immunochromatography assay(EICA) technology through introducing external electricity into the up-converting phosphor nanoparticle(UCNP)-based ICA system serving as a new driving force.Methods:[1] Construction of the theoretical model and experimental platform for EICA. A theoretical model for EICA was constructed in order to reveal the effects of electricity on chromatography. Diffusion dynamics of particles under the electric field is analyzed through the combination of initial-boundary conditions in UCNP-ICA. The EICA experimental platform was established based on the UCNP-ICA system. Consistence between the experimental and theoretical data was analyzed by real-time monitoring the signal intensity of the strips during the assay.[2] Study on the dynamical and biological effects of EICA. Firstly, electric fields of different directions and voltages were exerted to the UCNP-ICA strip for Yersinia pestis; the flow rate of UCNP particles and signal intensity of the strip were monitored and analyzed to evaluate the dynamical effects of different electric fields. Then, the biological effects of EICA were evaluated by determining the detection sensitivity of Y. pestis under different voltages of electric fields.[3] Evaluation of EICA in rapid detection of infectious pathogens. Performances of the EICA in detection of Y. pestis were comprehensively evaluated, including the limit of detection(LOD), quantitative linearity, and detecting precision, with the traditional UCNP-ICA as the control. Bacteria(Yersinia pseudotuberculosis, Yersinia enterocolitica and Bacillus anthracis, etc.) with close relation to Y. pestis or with the potential to be used for bioterrorism were used to test specificity of the EICA. Besides, Y. pestis solutions with different types of interferences(acid, alkali, sodium chloride, PEG 20000 and BSA) were prepared, which is used to test the sample tolerance of EICA and its capacity for on-site detection.Results: [1] Construction of the theoretical model and experimental platform for EICA. A phase-filed model for EICA was constructed with the particle concentration as theparameter. Then dynamical effects of the electric field were theoretically revealed by mathematical equations. Based on the conventional UCNP-ICA system we established the EICA platform, which could achieve real-time monitoring of the detecting signal intensities during the assay. The experimental results showed that the increase rate of signal intensity in the strip was increased by the electric fields of positive direction(in accordance with the flow direction). And, a high consistence was found between the theoretical predictions and experimental data of the increase rates of signal intensity under electric fields of different voltages.[2] Study on the dynamical and biological effects of EICA. The effects of positive electric fields could notably intensify the detecting signal intensities of the strip, while the electric field in opposite direction could suppress the signal growing. With the increase of voltages from 15 V to 50 V, the EICA could significantly increase the signal intensity; however, with the voltage grew to 60 V, the signal intensity came to decrease. Besides, the time the signal intensity comes to the plateau stage was gradually advanced with the increase of electric field; and it could be shorten to 5 min under 60 V. The results suggest that the EICA could effectually promote the release of signal particles from the conjugation pad and speed its flow rate on the strip. On the other hand, the detection sensitivity of Y. pestis under different voltages was tested, which resulted in that the detection sensitivity could be improved with the voltage grew when the assay was shortened to 5 min.[3] Evaluation of the EICA in rapid detection of infectious pathogens. The EICA could ahieve the detection of Y. pestis in 5 min witout interfering with the detection performance, including the detection sensitivity, quantitative linearity, precision, specificity, and sample tolerance. The LOD of Y. pestis with EICA was 5.0′102 CFU/m L, which is comparable to that of the traditional UCNP-ICA. The EICA could also accurately quantify the Y. pestis from 5.0′102 to 5.0′106 CFU/m L(R2=0.9978). No significant cross-reaction was found in the detection of other potential bioterrorism agents and the bacterial closely related to Y. pestis. The EICA presented good sample tolerance to Y. pestis solutions with HCl(p H ≥ 3), Na OH(p H ≤ 12), Na Cl(≤ 0.5 M), PEG 20000(≤ 5%), or BSA(≤ 200 mg/m L), maintaining the LOD of Y. pestis ranging from 5.0′102 CFU/m L to 5.0′103 CFU/m L.Conclusion: In the research, an electro-driven immunochromatography assay(EICA) technology was developed based on the UCNP-ICA. We first constructed a phased-field model for the EICA, theoretically revealing the effects of electric field on the flow dynamics. Then the dynamical and biological effects of EICA were comprehensively evaluated. It was indicated that the electricity could effectually promote the release of signal particles(UCNP-antibody) from the paper andaccelerate the flow rate, which could help the EICA achieve more rapid and sensitive detections. In the detection of Y. pestis, the EICA was proved that it could notably shorten the time cost from 15 min to 5 min, without suppressing the detecting performances. In summary, the EICA, with more potent driving force, could efficiently update performance of the traditional capillary action based- ICA; and, it is considered to be a more rapid and sensitive analytical technology for the rapid diagnosis of infectious diseases and other POCT applications. |
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