Masking the peroxidase-like activity of MoS2 nanozyme enables label-free lipase detection.

MoS2 nanoparticles (2D-nps) exhibit artificial enzyme properties which can be regulated at the bio-nano interfaces. We have discovered that protein lipase is able to tune the peroxidase-like activity of the MoS2 2D-nps offering low nanomolar label-free detection and identification in samples with unknown identity. The inhibition of the peroxidase-like activity of the MoS2 2D-nps was demonstrated to be concentration-dependent and as low as 5 nM of lipase was detected with this approach. The results were compared with several other proteins which did not display any significant interference with the nanozyme behavior of the MoS2 2D-nps. This unique response of lipase was characterized and exploited for successful identification of lipase in six unknown samples using qualitative visual inspection and a quantitative statistical analyses method. The developed methodology in this approach is noteworthy for many aspects; MoS2 2D-nps are neither labeled with a signaling moiety nor modified with any ligands for signal readout. Only the intrinsic nanozyme activity of the MoS2 2D-nps is exploited for this detection approach. No analytical equipment is necessary for the visual detection of lipase. The synthesis of the water-soluble MoS2 2D-nps is low-cost and can be performed in bulk-scale. Exploring the properties of 2D-nps and their interactions with the biological materials reveals highly interesting yet instrumental features which offers development of novel bioanalytical approaches.