Loading of hyaluronic acid-conjugated MoS2 nanosheets with rhodamine B for sensing hyaluronidase activity in human urine and live cells.

Efficient molecule loading onto nanomaterials is a key step for advanced biosensing and imaging because of improved sensitivity and enhanced targeting of the resultant nanoprobe. In contrast to other nanomaterials, MoS2 nanosheets (NSs) possess unique advantageous of large surface area and abundant sulfur defects. Herein, we explored the conjugation of MoS2 NSs with thiol-conjugated hyaluronic acid (HA-SH) for selective detection of hyaluronidase (HAase) and specific binding to CD44 receptor-positive cancer cells. Rhodamine B (RhB) molecules were electrostatically and hydrophobically coupled to the HA-SH-MoS2 NS surface with a binding constant of 7.14 × 1016 M-1. The HA-SH-MoS2 NS-mediated fluorescence quenching of the adsorbed RhB molecules proceeds via a combination of static and dynamic quenching in the ratio of 10:1. Upon the addition of HAase, the adsorbed RhB molecules are liberated from the RB-HA-SH-MoS2 NSs via HAase-mediated hydrolysis of HA-SH. As a result, the restored fluorescence of RhB molecules is proportional to the HAase concentration. The RhB-HA-SH-MoS2 NSs achieve a detection limit of 0.37 U/mL for HAase with a linear response range from 0.05 to 4.5 U/mL and satisfactory selectivity against potential interferents. The RhB-HA-SH-MoS2 NSs not only effectively quantify HAase in urine sample but also enable selective imaging of intracellular HAase activity through CD44 receptor-mediated endocytosis.