A ratiometric fluorescent platform based on xylan-derived carbon dots for detecting Vibrio parahaemolyticus

Abstract

It is a challenge to design a ratiometric fluorescent platform with a stable inner reference free from disturbing for detection. Herein, a ratiometric fluorescent platform (RFP) was fabricated for detection of Vibrio parahaemolyticus (V. parahaemolyticus) based on optically transparent silica nanoparticles which integrates fluorophores and specific aptamers. The platform incorporated Rhodamine B as an internal reference within the protective silica matrix, while xylan-derived carbon dots were evenly distributed on silica’s surface. When excited at 365 nm, RFP exhibited blue fluorescence at 430 nm and orange fluorescence at 575 nm. Blue fluorescence of these carbon dots was quenched through interaction with a Dabcyl-modified aptamer (Apt.D). Upon bacterial addition, changes in the fluorescence intensities were observed, enabling sensitive and ratiometric detection. Notably, this RFP-Apt.D has a low detection limit of 1.15 CFU/mL (S/N = 3) with a linear detection range from 8 CFU/mL to 8 ×10⁵ CFU/mL in a short responding time of 30 minutes, which was superior to most reported V. parahaemolyticus sensors. Furthermore, the RFP-Apt.D was successfully applied to detect V. parahaemolyticus in seawater and clam samples through a fast pretreatment without requiring enrichment and achieved reliable and satisfactory recoveries. This work provides a widely adaptable platform to design ratiometric fluorescent sensor for detection of foodborne pathogen.