Activity-Based Near-Infrared Fluorogenic Probe for Enabling in Vitro and in Vivo Profiling of Neutrophil Elastase

Abstract

Neutrophil elastase (NE), a typical hematopoietic serine protease, has significant roles in inflammatory and immune responses, and thus is highly associated with various diseases such as acute lung injury (ALI) and lung cancer. Rapid and accurate measurement of NE activity in biological systems is particularly important for understanding the role of NE in inflammatory diseases, as well as clinical diagnosis. However, the specific detection and noninvasive imaging of NE in vivo remains a challenge. To address this issue, a small-molecule substrate based near-infrared fluorogenic probe (NEP) for NE was constructed via incorporating pentafluoroethyl as the recognition group with a hemicyanine dye-based fluorophore. This initially quenched probe possesses more than 25-fold red fluorescence enhancement upon the catalysis of human NE, and the detection limit is about 29.6 ng/mL. In addition, the high specificity and the long emission wavelength (λ em max = 700 nm) of NEP allowed the direct monitoring of NE-trafficking, exogenous NE uptake, and endogenous NE upregulation at the cellular level. Moreover, the successful spatiotemporal imaging of NE in ALI model mice also made it a promising new tool in clinical diagnosis for ALI and other lung diseases.

Small-molecule fluorescence-based probes for interrogating major organ diseases

“…31). 46 NEP consists of a hemicyanine dye-based NIR fluorophore and a pentafluoropropionamide unit as the recognition unit for NE. 47 The addition of NE (0-10 mg mL À1 ) resulted in a 25-fold fluorescence increase at 700 nm (excitation wavelength 670 nm).…”

Activity-based NIR fluorescent probes based on the versatile hemicyanine scaffold: design strategy, biomedical applications, and outlook

“…69). 338 The probe NEP consists of a pentafluoroethyl group as the recognition moiety and a hemicyanine fluorophore as the signal reporter. Upon reaction with NE, the initially quenched probe NEP exhibited more than 25-fold fluorescence enhancement at 700 nm with a detection limit of 29.6 ng mL −1 .…”

Fluorescent probes for visualizing ROS-associated proteins in disease

“…Probe 80 was applied for the real-time monitoring of NE activity in an acute kidney injury (ALI) mouse model. 195 …”