A facile fluorescent sensor based on carbon dots and Fe3O4 nanoplates for the detection of hyaluronidase activity

Since the sensitivity of the sensing platform using carbon dots (CDs) alone is poor, the development of sensors based on the combination of CDs with other nanomaterials has attracted considerable interest. In this paper, a novel and facile method was established using CDs and Fe 3 O 4 nanoplates (NPs) for the determination of hyaluronidase (HAase) activity. Fe 3 O 4 NPs were introduced to quench the fluorescence of CDs through inner filter effect (IFE) for the first time. The negatively charged HA could bind to the positively charged Fe 3 O 4 NPs via electrostatic attraction to form HA/Fe 3 O 4 NPs complex, resulting in the weakening of the IFE between Fe 3 O 4 NPs and CDs. Hence, the fluorescence of CDs was recovered. With the presence of HAase, HA was hydrolyzed into small fragments which were unable to interact with Fe 3 O 4 NPs. Thus, the fluorescence of CDs was “turn-off” again by Fe 3 O 4 NPs. The activity of HAase was determined in a range of 0.0040−0.12 U mL −1 with a limit of detection of 0.0016 U mL −1 . Both the CDs and Fe 3 O 4 NPs were label-free, low-cost and eco-friendly, making the detection system simple and economical. The proposed method provides a new way of designing new sensing platform.