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

Pneumonia\nis a prevalent acute respiratory infection and a major\ncause of mortality and hospitalization, and the urgent demand for\na rapid, direct, and highly accurate diagnostic method capable of\ndetecting both Streptococcus pneumoniae (S. pneumoniae) and Klebsiella pneumoniae (K. pneumoniae) arises from their prominent roles as the primary pathogens responsible\nfor pneumonia. Herein, two luminescent iridium complexes with nonoverlapping\nphotoluminescence spectra, iridium(III)-bis [4,6-(difluorophenyl)-pyridinato-N,C<sup>2</sup>′] picolinate (abbreviated as Ir–B) and bis\n(2-(3,5- dimethylphenyl) quinoline-C2,N′) (acetylacetonato)\niridium(III)) (abbreviated as Ir-R), were unprecedently proposed to\nconstruct a novel wavelength-resolved magnetic multiplex biosensor\nfor simultaneous detection of S. pneumoniae and K. pneumoniae based on catalytic\nhairpin assembly (CHA) signal amplification strategy combined with\ndye-doped silica nanoparticles. Notably, the proposed wavelength-resolved\nmultiplex biosensor not only exhibits a broad linear range from 50\npM 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\nsamples, with corresponding relative standard deviation (RSD) values\nranging 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\napproach for the simultaneous detection of multiple pathogens in the\nfuture.