A Novel Phenoxazine-based Fluorescent Probe for the Detection of HOCl in Living Cells

Ex Tenebris Lux: Illuminating Reactive Oxygen and Nitrogen Species with Small Molecule Probes

Reactive oxygen and nitrogen species are small reactive molecules derived from elements in the air─oxygen and nitrogen. They are produced in biological systems to mediate fundamental aspects of cellular signaling but must be very tightly balanced to prevent indiscriminate damage to biological molecules. Small molecule probes can transmute the specific nature of each reactive oxygen and nitrogen species into an observable luminescent signal (or even an acoustic wave) to offer sensitive and selective imaging in living cells and whole animals. This review focuses specifically on small molecule probes for superoxide, hydrogen peroxide, hypochlorite, nitric oxide, and peroxynitrite that provide a luminescent or photoacoustic signal. Important background information on general photophysical phenomena, common probe designs, mechanisms, and imaging modalities will be provided, and then, probes for each analyte will be thoroughly evaluated. A discussion of the successes of the field will be presented, followed by recommendations for improvement and a future outlook of emerging trends. Our objectives are to provide an informative, useful, and thorough field guide to small molecule probes for reactive oxygen and nitrogen species as well as important context to compare the ecosystem of chemistries and molecular scaffolds that has manifested within the field.

Novel D-π-A type near-infrared fluorescent probes for the detection of Aβ40 aggregates

Aberrant accumulation of Amyloid-β (Aβ) peptide is closely related to Alzheimer's disease. Thus, it is important to develop featured probes for the specific detection of Aβ species. Herein, we designed and synthesized a novel near-infrared fluorescent probe SDPY based on the D-π-A architecture for the detection of Aβ aggregates. The probe SDPY displayed higher affinity for Aβ40 aggregates over Aβ42 aggregates in solution (Kd = 164 nM vs. 2.1 μM). In addition, SDPY showed excellent anti-interference against a wide range of other substances. Furthermore, SDPY was capable of labeling Aβ40 aggregates better than Aβ42 aggregates in the brain sections of AD transgenic mouse models.

Insight into hydroxyl radical-mediated cleavage of caged methylene blue: the role of Fenton's catalyst for antimalarial hybrid drug activation

Methylene blue with a 10-N carbamoyl linkage was reported to be a hydroxyl radical triggered cleavable ligand. Probed by this platform, hemoproteins were demonstrated to be a much more efficient Fenton's catalyst than commonly used inorganic Fe(ii) salts. The applicability of this ligand was demonstrated through the capability of being triggered by elevated reactive oxygen species levels at diseased tissue, with malaria-parasitized erythrocytes as an in vitro model.