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Time resolved fluorescence immunoassay technology opens a new era of ipoct intelligent detection!


The annual big bang of products falls on Qingdao this year. As expected, POCT manufacturers alone reached an unprecedented scale at this inspection medicine and blood transfusion instrument and reagent Expo, and Ruihui biology ranked among the top ten "IVD enterprises with the most craftsmanship spirit in China".
With the rapid development of science and technology, the detection sensitivity of many markers needs to reach pg / ml. the first generation POCT products based on colloidal gold chromatography still can not meet the requirements of sensitivity by increasing the amount of samples and prolonging the reaction time. Now they have gradually withdrawn from the historical dance stage. Instead, ordinary fluorescence immunochromatography products have improved their sensitivity, but ordinary fluorescence immunochromatography takes fluorescein as a marker. The results cannot be eliminated due to the influence of stray light, and the quantification is not accurate. The latest generation of POCT products came into being. Time-resolved fluorescence immunochromatography technology takes fluorescent microspheres as markers, with high sensitivity, no stray light interference and more accurate quantification.

1. Marker selection: fluorescein and fluorescent microspheres

Fluorescein is a small molecular compound with molecular weight of hundreds to thousands. It is crosslinked with antibody (antigen) through active groups, and produces fluorescence effect in final use for quantification. There are many kinds of fluorescein, and the excitation range almost covers the ultraviolet to infrared region. However, the influence of stray light cannot be eliminated and the quantification is inaccurate. As shown below:



Fluorescent microspheres are made by filling nano polystyrene microspheres with lanthanide elements (the most commonly used is europium EU). After crosslinking with antibody (antigen), the microspheres can be used for antigen (antibody) detection. Fluorescent microspheres have greater stock displacement than fluorescein. For example, the most common EU, the excitation light is 365nm, while the emission light is about 610nm, and the stock displacement is greater than 200nm. It can effectively eliminate the interference of excitation light and nonspecific fluorescence on signal acquisition and improve the specificity of test. EU is an inert element. Compared with fluorescein, it is not easy to be bleached by light, and the result is more stable.


Fluorescent microspheres have a long fluorescence attenuation time (500 ~ 2000us), while the fluorescence signal attenuation time of fluorescein is very short (5 ~ 100US). Based on this, fluorescent microspheres can develop time-resolved technology. The measurement time can be appropriately delayed and measured after the background fluorescence is completely attenuated, which can eliminate the interference of excitation and improve the accuracy of inspection.


Based on the above two points, it is not too much to say that the time-resolved fluorescence of nano microspheres has opened a new decade of POCT marker detection technology.



Comparison diagram of time-resolved fluorescence and ordinary fluorescence



2. Operation simplification: one-step and two-step

The so-called one step and two steps refer to the operation steps.

The one-step method simplifies the personnel operation by adding the sample to the reaction plate, which basically meets the performance requirements (mainly precision and accuracy) and reduces the operation intensity for low sensitivity projects (such as MAU). However, for heart markers, which are highly sensitive and valuable for the diagnosis of acute cardiovascular diseases, the one-step method of changing operation for performance is embarrassing.

Compared with the one-step method, the two-step method dilutes the sample before adding the reaction plate to effectively eliminate the interference of impurities in the sample, so as to improve the precision and accuracy, and ensure that the test results will not mislead patients for treatment due to insufficient performance.


3. Antigen antibody

Fawalski, a lifelong academician of Russian aeroengine, said: "all things on aircraft increase resistance and weight, but the engine improves power. As long as the engine is good, it can fly with a piece of wood."

This principle also applies to products based on antigen antibody reaction. Good antigen antibody is like a good engine. In any case, high-quality and stable biological raw materials should be selected. The quality of antigen antibody accounts for at least 50% of the product quality. Therefore, the antigens and antibodies used in Ruihui biological products come from internationally renowned manufacturers, and the stable product quality is ensured through strict quality control and matching.


4. Spring of domestic equipment

In January 2017, the notice of Sichuan Provincial Department of Finance on publishing the list of imported products purchased by provincial governments in 2017, which was posted on the Sichuan provincial government procurement network, explicitly required that hospitals (or units) with grade II and below should use domestic products of 93 kinds of medical equipment; At the national level, Zhejiang, Shanghai, Jiangsu, Guangdong and Sichuan are included in the first batch of pilot promotion of domestic medical equipment.

In March 2017, China Medical Equipment Association released the third batch of excellent domestic medical equipment product catalogue, and POCT products entered the catalogue of excellent domestic medical equipment for the first time.

The coincidence of the government and the association seems to be calling the world tomorrow. The spring of domestic equipment is not far away, especially for time-resolved fluorescence immunochromatography. Ruihui biological seized the dividend given by the times, continuously improved the comprehensive strength of products, raised POCT time-resolved immunochromatography technology to a new level, focused on precision medicine and opened a new era of ipoct intelligent detection!