Development of an advanced dual-probe fluorescence platform for sensitive and rapid detection of Porphyromonas gingivalis in saliva

Rapid and accurate detection of Porphyromonas gingivalis ( P. gingivalis ) is crucial for the timely diagnosis and management of periodontal diseases as well as for elucidating its role in systemic conditions. However, conventional diagnostic methods are complex, time-consuming, and unsuitable for point-of-care testing, necessitating the development of a more efficient and accessible detection system. This study presents a novel dual-probe fluorescence platform featuring cadmium telluride quantum dots (CdTe QDs) and a specially designed probe (PAN) as fluorescent molecules, which does not require a washing step. The PAN and CdTe QD probes can efficiently differentiate between Cu 2 + and Cu + ions through ionic hydrolysis and cation exchange reactions, respectively, resulting in the sensitive and rapid detection of arginine-specific gingipain, a key biomarker for P. gingivalis . Furthermore, the color change of CdTe QDs upon contact with saliva samples facilitates the visual identification of P. gingivalis . This dual-probe platform demonstrated a higher signal-to-noise ratio and greater reliability compared to the single-probe methods. Moreover, this platform features a low detection limit of 5 and 20 colony-forming units (CFUs)/mL for the PAN and CdTe QDs signals, respectively, with a visual detection threshold as low as 200 CFU/mL. Thus, this platform provides quantitative and qualitative results that are 100 % in concordance with quantitative PCR results from clinical saliva samples of patients with periodontitis and healthy controls. This simple, rapid, and cost-effective diagnostic tool can be potentially used for point-of-care applications, enabling early detection and improved monitoring of oral health and related diseases.