Development of SPQC Biosensor for <i>Streptococcus pneumoniae</i> Detection Based on IscB Nuclease Recognition

<i>Streptococcus pneumoniae</i> is a major pathogen responsible for a wide range of infectious diseases in humans and is also the bacterium that causes the most deaths in children. Consequently, the rapid and accurate detection of <i>S. pneumoniae</i> is crucial for public health management. The IscB protein of the OMEGA (obligate mobile element-guided activity) system, as a programmable RNA-guided DNA endonuclease, shows high application potential for detecting single-nucleotide mismatches. This study developed a novel series piezoelectric quartz crystal (SPQC) sensor for <i>S. pneumoniae</i> detection based on specific recognition of IscB, combined with rolling circle amplification and urease-catalyzed urea hydrolysis. The biosensor demonstrates rapid detection of <i>S. pneumoniae</i> nucleic acids across 10³-10⁸ CFU/mL within 3 h, exhibiting a detection limit of 550 CFU/mL. This sensor has excellent selectivity, and common bacteria do not interfere with the detection of <i>S. pneumoniae</i>. This biosensing platform demonstrates significant potential for clinical diagnostic applications.