Persistent and ultrastable chemiluminescence “super enriching” on single microbead for sensing attomolar biomarkers

We propose a novel single microbead “chemiluminescence (CL) super enriching and imaging” strategy that efficiently concentrates highly intense, long-lasting, and ultrastable CL shining on only a single microbead (SMB), allowing for the ultrasensitive quantification of various biomarkers at the attomolar level. Aided by a phenothiazine derivative enhancer, the traditional flash-type CL of horseradish peroxidase (HRP)-H2O2-luminol can be efficiently converted into a significantly enhanced (103-fold), persistent, and ultrastable CL emission (E-CL) that can be exactly confined and accurately imaged on the microbead interface. Then, by employing only one minuscule-sized SMB as the sole reaction and signaling unit, the target as well as the aroused E-CL signal concentrated on the SMB can further achieve ~104 “super-enriching” efficiency. Therefore, by “super enriching” target-responsive E-CL signal on an SMB, the SMB E-CL imaging strategy provides a powerful tool for the attomolar-level detection of various biomarkers including proteins, microRNAs, and virus DNA.