Photoluminescent and multi-phonon resonance Raman scattering dual-mode immunoassays based on CdS nanoparticles for HIgG detection.

A dual-mode immunoassay strategy based on CdS nanoparticles as signal probes with both of photoluminescent (PL) and multi-phonon resonance Raman scattering (MRRS) properties was developed. Simplified structural design and preparation were achieved due to the intrinsic integration of PL and MRRS dual signals in the single-unit CdS nanoprobes. Human immunoglobulin G (HIgG) was sensitively and specifically detected using the proposed PL-MRRS dual-mode strategy. The linear relationship between the HIgG concentration and the intensity of 707 nm PL peaks/300 cm MRRS peaks under the excitation of 488 nm laser was established. The limit of detection was 0.93 fg mL for PL and 1.10 fg mL for MRRS. In comparison with previous IgG detection methods, the proposed method exhibited prominent advantages in detection sensitivity and working range with good stability and repeatability. An internal self-calibration was realized which ensured the accuracy and reliability of detection results. Both results of specificity experiments and serum sample analysis further confirmed the feasibility of the designed immunoassay strategy in practical serological detection.