Wavelength-Resolved Magnetic Multiplex Biosensor for Simultaneous and Ultrasensitive Detection of Pneumonia Pathogens via Catalytic Hairpin Assembly Strategy with Luminescent Iridium Complexes

Pneumonia is a prevalent acute respiratory infection and a major cause of mortality and hospitalization, and the urgent demand for a rapid, direct, and highly accurate diagnostic method capable of detecting both Streptococcus pneumoniae (S. pneumoniae) and Klebsiella pneumoniae (K. pneumoniae) arises from their prominent roles as the primary pathogens responsible for pneumonia. Herein, two luminescent iridium complexes with nonoverlapping photoluminescence spectra, iridium(III)-bis [4,6-(difluorophenyl)-pyridinato-N,C²′] picolinate (abbreviated as Ir–B) and bis (2-(3,5- dimethylphenyl) quinoline-C2,N′) (acetylacetonato) iridium(III)) (abbreviated as Ir-R), were unprecedently proposed to construct a novel wavelength-resolved magnetic multiplex biosensor for simultaneous detection of S. pneumoniae and K. pneumoniae based on catalytic hairpin assembly (CHA) signal amplification strategy combined with dye-doped silica nanoparticles. Notably, the proposed wavelength-resolved multiplex biosensor not only exhibits a broad linear range from 50 pM to 10 nM but also demonstrates excellent recovery rates for S. pneumoniae (96.1–99.3%) and K. pneumoniae (94.8–101.5%) in real clinical samples, with corresponding relative standard deviation (RSD) values ranging from 2.57 to 3.15% for S. pneumoniae and 1.45 to 3.17% for K. pneumoniae. These favorable experimental outcomes undoubtedly offer a promising approach for the simultaneous detection of multiple pathogens in the future.