Paper-based laser induced fluorescence immunodevice combining with CdTe embedded silica nanoparticles signal enhancement strategy

Paper-based laser induced fluorescence immunodevice for alpha fetoprotein (AFP) detection was developed in this work by using CdTe quantum dots (QDs) embedded silica nanoparticles as the signal enhancement label. A homemade laser induced fluorescence device with two optical fibres was used here for the fluorescence detection. Laser issued by a semiconductor laser light source (405 nm, 1 mW) was exposed to the paper-based chip with very lower background through an optical fiber and the fluorescence (542 nm) induced by laser was collected to a photomultiplier tube (PMT) through a glass fiber. The paper-based chip was fabricated by the wax-printing method and the antibody can be directly immobilized on the plasma treated paper surface. Then CdTe QDs embedded silica nanoparticles with the signal enhancement function was labeled on the signal antibody. After a sandwich-type immunoreaction, AFP was linearly detected in the range from 0.001 ng/mL to 20:0 ng/mL with a detection limit of 0.4 pg/mL. Laser induced fluorescence with the homemade device was for the first time applied on the paper-based chip with very higher sensitivity. What's more, the proposed strategy opened a promising platform for sensitive monitoring of cancer biomarkers in biological analysis and medical diagnostics. (C) 2016 Elsevier B.V. All rights reserved.