Development of a fluorescent label tool based on lanthanide nanophosphors for viral biomedical application

Quoc Minh Le, Thu Huong Tran, Thanh Huong Nguyen, Thi Khuyen Hoang, Thanh Binh Nguyen, Khanh Tung Do, Kim Anh Tran, Dang Hien Nguyen, Thi Luan Le, Thi Quy Nguyen, Mai Dung Dang, Nu Anh Thu Nguyen and Van Man Nguyen

Abstract

We report for the first time the preparation of luminescent lanthanide nanomaterial (LLN) linked bioconjugates and their application as a label tool for recognizing virus in the processing line of vaccine industrial fabrication. Several LLNs with the nanostructure forms of particles or rods/wires with europium (III) and terbium (III) ions in lattices of vanadate, phosphate and metal organic complex were prepared to develop novel fluorescent conjugates able to be applied as labels in fluorescence immunoassay analysis of virus/vaccine.

With regard to the LLNs, we have successfully synthesized nanoparticles around 10 nm of YVO₄:Eu(III), with high emission in the red spectral region, nanorod and nanowire of TbPO₄H₂O and Eu_1-xTb_xPO₄H₂O, width 5–7 nm and length 300 nm, showing very bright luminescence in green, and core/shell nanosized Eu(III) and Tb(III)/Eu(III) complexes with naphthoyl trifluoroacetone and tri-n-octylphosphineoxide (Eu.NTA.TOPO@PVP, Eu_XTb_1-X.NTA.TOPO). The appropriated core/shell structures can play a double role, one for enhancing luminescence efficiency and another for providing nanophosphors with better stability in water media for facilitating the penetration of nanophosphor core into a biomedical environment.

The organic functionalizations of the obtained LLNs were done through their surface encapsulation with a functional polysiloxane including active groups such as amine (NH₂), thiocyanate (SCN) or mecarpto (SH). The properties of functional sol-gel matrix have great influence on the luminescence properties, especially luminescence intensity of YVO₄:Eu(III), Eu.NTA.TOPO@PVP, TbPO₄H₂O and Eu_xTb_1-xPO₄H₂O. Bioconjugation processes of the functionalized LLNs have been studied with some bioactive molecules such as biotin, protein immunoglobulin G (IgG) or bovine serum albumin (BSA).

The results of LLN-bioconjugate linking with IgG for recognizing virus (vaccine) will be presented in brief. It is consistent to state that the LLN bioconjugates prepared from YVO₄:Eu(III)–nanoparticles, TbPO₄H₂O nanorod or wire and EuNTA.TOPO@PVP nanosized core/shell complex could be used as labels for recognizing virus in diagnosis or in vaccine production by use of the fluorescence immunoassay (FIA) method. The fluorescence images of the incubated specimens consisting of LLN bioconjugate and vaccine fabricate could be obtained well in terms of sharpness, reproductivity and stability.

However, much work still needs to be done to develop an ordinary LLN-conjugate using the FIA method for analysis of virus and, moreover, to extend the study of biomedical cell processes at nano/microscale in practical application