DVB-cross-link latex microspheres to uniformly host Eu(Ⅲ) chelates with moderate swelling capacity for high performance quantitative LFIA strips

Abstract

Eu complex swollen polystyrene (PS) fluorescent microspheres have already attracted considerable attention in the field of lateral flow immunoassay (LFIA) biodetection. However, the over excessive swelling and the induced concentration quenching effect of Eu complexes often deteriorates the fluorescence intensity as well as their fluorescence efficiencies. To address this issue, herein we synthesized Eu(TTA)₃(TPPO)₂ and introduced divinylbenzene (DVB) to fabricate threedimensionally cross-link PS-DVB-Eu microspheres, in order to get a moderate swelling capacity of Eu complexes without obvious fluorescence concentration quench. This cross-link structure effectively promotes the homogeneous distribution of the swollen Eu(TTA)₃(TPPO)₂ in PS-DVB-Eu microspheres. It thus brought an improved fluorescence properties with a high internal quantum efficiency (IQE) of 52.36% and a lifetime of 539 μs. The fluorescence of the cross-link PS-DVB-Eu microspheres was 3.85 times stronger than that of non-crosslink PS-Eu microspheres. The cross-link structures also helped PS-DVB-Eu microspheres to hold a relatively high Zeta potential and a surface carboxyl concentration large enough. These merits support PS-DVB-Eu microspheres to get an enhanced lateral flow immunoassay (LFIA) performance, including a LOD of 0.08 ng/mL and a CV value less 7.34% on detecting C-reactive protein (CRP). It demonstrated the cross-link PS-DVB-Eu microspheres as a promising material for high performance LFIA point-of-care testing technique.