A Carcinoembryonic Antigen Detection System Based On A Microfluidic Paper-based Analytical Device

Carcinoembryonic antigen(CEA)is one of the most common tumor markers in cancer screening and diagnosis.Normally,the concentration of CEA in the serum of healthy adults is below 2.5～5 ng/m L,while the content of CEA in patients with malignant tumors will increase sharply.Therefore,quantitative detection of CEA contributes to the preliminary screening and pre-diagnosis for malignant tumors.Combined with point-of-care testing(POCT)technology,microfluidic paper-based analytical devices(μPADs)are able to achieve rapid,accurate and efficient quantification of CEA by a simple and portable detection method,which is much helpful for promoting cancer screening and pre-diagnosis in less developed regions and small or medium medical institutions such as community hospitals,clinics and physical examination centers.μPADs combined with a smartphone-based detection platform enable the detection of CEA to meet the requirements of POCT such as rapidity,accuracy and portability on site.In this study,a 3D multilayered roundμPAD with multichannel was designed and developed for the rapid detection of CEA.The μPAD mainly contained multiple microchannels,five detection units,a splitting layer,a rotatable detection layer and a blotting layer.The rotatable detection layer serving as a valve enabled the microchannels on the μPAD to switch between connected and disconnected states,which facilitated the reaction duration controlling and washing operations during the immunoassays.It was demonstrated in the study that wax-printing with heating is an effective method for the fabrication of the μPAD by generating desirable microfluidic effects and reaction results.Through a series of optimization experiments,the study determined optimum reaction conditions and a colorimetric signal indicator to accurately express colorimetric results of CEA immunoassay.Then a standard curve was established.Furthermore,the study developed a smartphone-based detection program to analyze and display the results of CEA immunoassays on theμPAD.By optimizing image processing algorithms for the colorimetric results on the μPAD,the program was able to automatically identify multiple detection areas and calculate CEA concentrations corresponding to each area.The proposed detection system showed a linear dynamic detection range of CEA from 0.5 ng/m L to 70 ng/m L,and the limit of detection(LOD)reached 0.015 ng/m L with favorable repeatability and accuracy.After analyzing 50 positive and 40 negative human serum samples,sensitivity and specificity of the system for detecting CEA was98% and 97.5% respectively,which indicated that the method in this study has excellent clinical performance for CEA detection.Compared with conventional immunoassays,the proposed detection system greatly simplified the procedures of CEA quantification with a few samples,which revealed broad application prospects and considerable clinical application potential.