Spectrum-Based Electrochemiluminescent Immunoassay with Ternary CdZnSe Nanocrystals as Labels

Abstract

Conventional electrochemiluminescence (ECL) research has been performed by detecting the total photons (i.e., the ECL intensity). Herein, systematic spectral exploration on the ECL of dual-stabilizers-capped ternary CdZnSe nanocrystals (NCs) and its sensing application were carried out on a homemade ECL spectral acquiring system. The ternary CdZnSe NCs could be repeatedly injected with electrons via some electrochemical ways and then result in strong cathodic ECL with the coupling of ammonium persulfate. ECL spectrum of the CdZnSe NCs was almost identical to corresponding photoluminescence spectrum, indicating that the excited states of CdZnSe NCs in ECL were essentially the same as those in photoluminescence. Importantly, after being labeled to the probe antibody (Ab2) of α-fetal protein (AFP) antigen, the ternary NCs in the Ab2|NCs conjugates could preserve their ECL spectrum very well. A spectrum-based ECL immunoassay was consequently proposed with the CdZnSe NCs as ECL tags and AFP as target molecules. The limit of detection is 0.010 pg/mL, with a signal-to-noise (S/N) ratio of 3, indicating a sensitive ECL sensing strategy that was different from the conventional ones. This work might open a pathway to the spectrally resolved ECL analysis with even-higher S/N ratios than the fluorescent analysis.

Spectrum‐Based Electrochemiluminescence Immunoassay for Selectively Determining CA125 in Greenish Waveband

“…Although Ab 2 might partially block the ECL processes related to NCs in Ab 2 ‐NCs conjugates, both bare CdSe NCs and the Ab 2 |NCs conjugates displayed well‐defined ECL potential profiles with peak potentials around −1.30 and −1.45 V, respectively, only slightly decreased ECL intensity and negatively shifted peak potential were observed for Ab 2 ‐CdSe conjugates to those for bare CdSe NCs. The ECL spectra of both CdSe NCs and Ab 2 ‐CdSe conjugates displayed a sharp symmetric peak around 555 nm with FWHM around 39 nm (curve b & c, inset B of Figure 1), which were almost identical to the PL spectrum of bare CdSe NCs, indicating the excited states of the CdSe NCs in Ab 2 ‐CdSe conjugates for ECL were the same to those of bare CdSe NCs for PL.…”

“…The ECL spectra of the proposed ECL immunoassay were almost identical to bared CdSe NCs’ PL spectrum, indicated a spectrum‐based ECL quantitative assay with similar color‐selectivity to that of NCs‐based fluorescent assay. Moreover, FWHM of the proposed ECL immunoassay was much narrower to that of the spectral ECL immunoassay with dual‐stabilizers‐capped CdZnSe NCs and CdTe NCs as tags . Because both the dual‐stabilizers‐capped CdZnSe NCs, CdTe NCs and CdSe NCs were synthesized in the same way and with the same stabilizers, only slightly changed precursors and refluxing time were involved in synthesizing procedures, the dual‐stabilizers‐capped strategy might be promising to prepare tags for spectrum‐based ECL immunoassay with further improved color‐selectivity on suitable synthesizing conditions.…”

“…The common optical, electrochemistry and ECL characterizations were performed with the apparatuses and methods reported previously (Supporting information) . ECL spectra were recorded by a homemade ECL spectrum acquiring instrument, including a VersaSTAT 3 electrochemical analyzer (Princeton Applied Research, USA), a digital CCD camera (PyLoN 400BReXcelon, Princeton Instruments, USA) coupled monochromator (Acton SP2300i, Princeton Instruments, USA) and a man‐made light‐tight box.…”

Electrogenerated Chemiluminescence of Semiconductor Nanoparticles and Their Applications in Biosensors

“…The produced ECL emission was strong enough to quantify AFP with ECL spectra. A linear relationship of ECL vs. AFP concentration was obtained from 0.10 to 50.0 pg/mL and the reported detection limit was 0.010 pg/mL …”

Nanomaterials in Electrochemiluminescence Sensors

“…Most of conventional ECL researches have been performed by detecting the total photons, because it is difficult to timely and exactly record the ECL spectrum within the proceeding of an unstable electrochemical reaction. Recently, Zhang and coworkers presented a dual‐stabilizers‐capped ternary CdZnSe nanocrystals to realize systematic spectral exploration via a homemade ECL spectral acquiring system . The ternary CdZnSe nanocrystals exhibit excellent electrochemical stability and passivated surface states, resulting in the protected excited states under different conditions.…”