Sialic
acids (SAs) are commonly located on the cell surface as
terminal ends of glycoproteins and glycolipids. Neuraminidase (NEU)
is a class of glycoside hydrolase enzymes that can cleave SAs from
receptors. Both SA and NEU play important roles in human physiological
and pathological processes of cell–cell interaction, communication,
and signaling. Additionally, bacterial vaginosis (BV), a form of gynecological
inflammation caused by dysbiosis of the vaginal microbiome, results
in the abnormal activity of NEU in vaginal fluid. Here, we developed
a novel probe for rapidly and selectively sensing SA and NEU based
on a one-step prepared boron and nitrogen codoped fluorescent carbon
dots (BN-CDs). The selective recognition reaction between SA and the
phenylboronic acid groups on the surface of BN-CDs inhibits fluorescence
emission from BN-CDs, while the NEU-catalyzed hydrolysis of SA bound
on BN-CDs leads to fluorescence recovery. The probe was applied in
diagnosing BV and showed consistent results to Amsel criteria. Moreover,
the low cytotoxicity of BN-CDs facilitates its application in fluorescence
imaging of SA on the membrane of red blood cells (RBCs) and leukemia
cell lines (U937, KAS-1). The excellent sensitivity, accuracy, and
applicability of the developed probe support its broad potential applications
in future clinical diagnosis and treatment.