A novel microfluidic photoelectrochemical (PEC) analytical
device
based on AgBiS2@Ag nanozyme-mediated signal amplification
was developed for ultrasensitive detection of cytokeratin 19 fragment
21–1 (CYFRA 21–1). First, a brand new Z-scheme BiVO4/ZnIn2S4 (BZIS) photoactive material
was utilized as a sensing matrix to supply a stable photocurrent.
Under anodic bias, the photoexcited holes in BiVO4 could
oxidize water to produce hydrogen peroxide (H2O2), which markedly enhanced the separation efficiency of the electron–hole
pairs. Besides, the Z-scheme heterojunction formed between BiVO4 and ZnIn2S4 further accelerated the
transport of the electron. Second, for improving the sensitivity of
the PEC sensor, a new strategy of catalytic dissociation of the hole-derived
H2O2 by AgBiS2@Ag nanozyme was proposed
to amplify the PEC signal. AgBiS2@Ag composites, possessing
an excellent peroxidase-mimicking feature, could efficiently catalyze
the H2O2 to produce hydroxyl radicals (•OH) and lead to the significant enhancement of the
photocurrent. Third, automatic sample injection and detection were
successfully realized by integrating the photoelectrode into microfluidic
chips. Based on this advanced sensing strategy, the designed microfluidic
PEC sensor displayed a wide linear range (0.1 pg/mL – 100 ng/mL)
and a low detection limit of 35 fg/mL (S/N = 3), which could be efficiently
applied to the ultrasensitive determination of CYFRA 21–1 in
a human serum sample.