Novel Fluorescent Probe TH-1 Unveiled for Targeted Protein Degradation

Fluorescent probes typically consist of a fluorescent molecule coupled with a targeting moiety that binds selectively to the desired target. Upon excitation with light of a specific wavelength, these probes emit light at a longer wavelength, producing a characteristic fluorescent signal that can be detected and quantified. The versatility of these probes allow for a wide range of applications, including tracking biomolecules such as proteins, nucleic acids, and ions, monitoring cellular processes in real-time, and diagnosing diseases, such as Alzheimer’s and urinary diseases (1,2).

As a result, the development of new fluorescent probes could allow for researchers to learn more about biological conditions. In a recent study published in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, lead author Bo Liu from Hubei Minzu University and Chongqing University of Arts and Sciences, along with their team, introduced a novel fluorescent probe, TH-1, that is designed for applications that require targeted protein degradation (3).

Thalidomide is a ligand for cereblon (CRBN) and has emerged as a focal point for its potential in targeted protein degradation (3). Leveraging this, the researchers aimed to enhance the optical and biocompatible characteristics of hydrazine fluorescent probes, resulting in the creation of TH-1 (3).

TH-1 has several characteristics worth mentioning. For example, the TH-1 probe can conduct its analysis rapidly, possessing a fast response time (3). The TH-1 probe also has significant colorimetric alterations, high sensitivity, and great selectivity (3).

In their study, the researchers applied TH-1 in bioimaging of hydrazine within living A549 cells successfully. Furthermore, by employing thalidomide, a clinically approved drug, as a fluorescent skeleton, the study expanded the repertoire of fluorescent skeleton libraries, promising further advancements in fluorescent probe development (3).

The researchers indicated that all chemical solvents and reagents were sourced from commercial suppliers without the need for additional purification. Spectroscopic analyses, including ¹H NMR, ¹³C NMR, and high-resolution mass spectrometry (HRMS), were conducted ensuring the accuracy and reliability of the obtained results (3).

As a result, the study shows that TH-1 exhibits rapid recognition of hydrazine hydrate in a PBS/DMF buffer at physiological pH (3). TH-1 utilizes thalidomide as the fluorophore and employs the acetyl ester moiety as the recognition site for hydrazine (3). The probe demonstrates minimal fluorescence initially, but upon interaction with hydrazine, the acetyl ester undergoes partial cleavage through hydrazine-triggered deprotection, leading to a marked increase in fluorescence intensity (3).

This research not only sheds light on the development of advanced fluorescent probes but also holds promise for diverse applications in targeted protein degradation and bioimaging, with potential implications for therapeutic interventions and biomedical research.

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References

(1) An, J.; Kim, K.; Lim, H. J.; et al. Early Onset Diagnosis in Alzheimer’s Disease Patients via Amyloid-β Oligomers-sensing Probe in Cerebrospinal Fluid. Nat. Commun. 2024, 15, 100.

(2) Xu, C.; Pu, K. Nat. Rev. Bioeng. 2024, https://doi.org/10.1038/s44222-024-00153-w

(3) Fu, D.; Wang, X.; Liu, B. Old Drug, New Use: The Thalidomide-based Fluorescent Probe for Hydrazine Detection. Spectrochimica Acta Part A: Mol. Biomol. Spectrosc. 2024, 309, 123808. DOI: 10.1016/j.saa.2023.123808