Photonic
crystals (PCs) have emerged as a promising electrochemiluminescence
(ECL) matrix in the domain of immunoassay. Making maximum use of light
manipulation properties of PCs is highly desired for improving the
sensitivity. In this work, we proposed a band-edge effect-induced
ECL enhancement strategy based on silica inverse opal PCs (SIOPCs).
By fine-tuning the lattice constant and carefully calibrating the
stopband position, we found that the band edge of the stopband exerted
significant influences on the ECL intensity and spectral distribution.
The high density of states at the blue edge of the photonic band gap
increased the radiative transition probability of ECL emitters and
enhanced the photon extraction during propagation, giving rise to
âŒ20-fold ECL signal amplification accompanied by a redistributed
ECL spectrum for the RuÂ(bpy)3
2+-TPrA system.
In combination with the intrinsic structural superiority, like large
specific surface area and interconnected macropores, the developed
SIOPC electrode was successfully applied in constructing a sandwich-type
immunosensor. The fabricated immunosensor displayed a very low detection
limit of 0.032 pg/mL and a wide linear range of 0.1 pg/mLâ150
ng/mL for a carcinoembryonic antigen assay, showing its potential
application in disease diagnosis.