Janus
amphiphilic particles have gained much attention for their
important application value in areas as diverse as interfacial modification,
sensors, drug delivery, optics, and actuators. In this work, we prepared
Janus amphiphilic nanosheets composed of nitrogen-doped stratiform
meso-macroporous carbons (NMC) and molybdenum sulfide (MoS2) for hydrophilic and hydrophobic sides, respectively. The dicyandiamide
and glucose were used as precursors for synthesizing two-dimensional
nitrogen-doped meso-macroporous carbons, and the molybdate could be
anchored by the functional groups on the surface of carbon layers
and then transform into uniformly MoS2 to form the Janus
amphiphilic layer by layer NMC/MoS2 support. Transmission
electron microscopy, scanning electron microscopy, X-ray photoelectron
spectroscopy, and Fourier transform infrared spectroscopy are used
to demonstrate the successful preparation of Janus materials. As the
typical interfacial enzyme, Candida rugosa lipase (CRL) immobilized on the Janus amphiphilic NMC/MoS2 support brought forth to improvement of its performance because
the Janus nanosheets can be easily attached on the oil–aqueous
interface for better catalytic activity (interfacial activation of
lipases). The obtained immobilized lipase (NMC/MoS2@CRL)
exhibited satisfactory lipase loading (193.1 mg protein per g), specific
hydrolytic activity (95.76 U g–1), thermostability
(at 55 °C, 84% of the initial activity remained after 210 min),
pH flexibility, and recyclability (60% of the initial activity remained
after nine runs). In terms of its application, the esterification
rate of using NMC/MoS2@CRL (75%) is higher than those of
NMC@CRL (20%) and MoS2@CRL (11.8%) in the “oil–water”
biphase and CRL as well as NMC/MoS2@CRL in the one-phase.
Comparing with the free CRL, NMC@CRL, and MoS2@CRL, the
Janus amphiphilic NMC/MoS2 served as a carrier that exhibited
more optimal performance and practicability.
An AIE dual-reactive supramolecular probe has been devised to simultaneously measure endogenous lipase and α-amylase activity in a homogeneous system. Fluorescence quantitative analysis of lipase and α-amylase in real biological samples enables rapid and accurate diagnosis of diseases.
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