Single layer molybdenum disulfide as an optical nanoprobe for 2 photon luminescence and second harmonic generation cell imaging.

Abstract

More recently, tremendous progress has been achieved in the development of two-dimensional semiconductor materials applied in catalyst, energy application, sensor device and bioengineering since the birth of graphene isolated from graphite. Layered molybdenum disulfide (MoS2 ) as an indirect gap semiconductor can efficiently emit photoluminescence (PL) excited by visible light, which shows a great potential in adaptive biological imaging. However, 1 photon PL of MoS2 for cell imaging purposes suffers from strong autofluorescence and ion-induced PL quenching. Herein, we report single layer small chitosan decorated MoS2 nanosheets as a nonbleaching, nonblinking optical nanoprobe under near infrared femtosecond laser excitation and their applications for strong 2 photon luminescence (TPL) and strong second harmonic generation (SHG) bioimaging. Furthermore, the TPL can resist the ion-induced quenching on the cellular membrane. The proposed TPL and SHG of single-layer MoS2 show great potential for real-time, deep, multiphoton and three-dimensional bioimaging under low-power laser excitation.