ex vivo optical imaging

ERNT is a fluorescent probe for monitoring endoplasmic reticulum (ER) polarity and detecting endoplasmic reticulum stress (ERS) during the progression of dynamic liver injury. ERNT functions based on a donor-π-acceptor (D-π-A) structure with an intramolecular charge transfer (ICT) effect. ERNT has multiple excitation/emission pairs: for in vitro cell imaging, the green channel has Ex/Em = 488/500-550 nm, and the red channel has Ex/Em = 488/570-620 nm; for in vivo liver imaging, Ex/Em = 520/620 nm; for solvent optical tests, Ex = 470 nm, with the maximum emission peak at 548 nm in low-polarity toluene and 668 nm in high-polarity DMSO. ERNT can evaluate the efficacy of hepatoprotective interventions by detecting changes in ER polarity, and also exhibits excellent photostability and low cytotoxicity .

HS-CyBz is a Fluorescent probe for H₂S detection, enabling ratiometric optical/photoacoustic dual-modality in/ex vivo imaging. Its detection mechanism relies on nucleophilic substitution of its benzoic ester group by HS⁻, which releases an enolic meso-hydroxyltricarboheptamethine cyanine that then undergoes keto-enol tautomerization to form Cy-ketone; this tautomerization causes distinct shifts in absorption and emission spectra, producing a ratiometric response that reduces interferences from tissue scattering, autofluorescence, and probe concentration. In its initial state, HS-CyBz has an excitation wavelength of 595 nm, with emission bands centered at 805 nm (main) and 630 nm (minor); upon reaction with H₂S, the 805 nm emission band decreases while the 630 nm band drastically increases, and its absorption spectrum shows a sharp band at 775 nm and a shoulder band at 708 nm, which decrease upon H₂S reaction with a minor increase at 850 nm and an isosbestic point at 825 nm. For in vivo optical imaging, excitation at 560 nm is used with emission channels at 620 nm and 790 nm, while in vivo photoacoustic imaging uses excitation at 775 nm and 825 nm. The detection limit of HS-CyBz for H₂S is 0.5 μM, and it shows high selectivity, with only H₂S inducing a distinct enhancement of the emission ratio F₆₃₀/F₈₀₅ and PA ratio PA₈₂₅/PA₇₇₅, while other biochemical species including cations, anions, reactive oxygen species, biothiols, and carboxylesterase trigger only minor changes and do not interfere with H₂S sensing. Tail intravenous injection of HS-CyBz leads to accumulation in the liver of mice, and it can be used to verify endogenous H₂S upregulation triggered by S-adenosyl-L-methionine via ratiometric optical/photoacoustic imaging .

AF647 Cadaverine is a far-red fluorescent polarity tracer. AF647 Cadaverine possesses a primary amine group that enables covalent labeling of carboxylic acids via carbodiimide activation or covalent labeling of glutamine residues through transamidation, rendering it applicable for bioconjugation, cell imaging, and blood-brain barrier permeability assays (Ex/Em = 651/670 nm) .