two-photon fluorescent probe

5-Nitro BAPTA tetramethyl ester is a calcium chelator. 5-Nitro BAPTA tetramethyl ester involves in the two-photon probe synthesis, and is used for real-time imaging of intracellular calcium ions, calcium waves monitoring at a depth of 100-300 μm in liver tissues for 1100-4000 s. 5-Nitro BAPTA tetramethyl ester, together with fluorescent compound 2-Me-substituted TM, can be used to form a red fluorescent probe (CaTM-2 AM) .

BTNPO is a unimolecular two-photon fluorescent probe.

TP-TRFS is a highly selective and the first two-photon fluorescent probe of thioredoxin reductase (TrxR) .

ASMI is a ratiometric, two-photon excited fluorescent probe, composed of a highly two-photon active and biocompatible merocyanine fluorophore and an acrylate moiety as a thiol reactive site. ASMI is able to selectively detect and monitor mitochondrial Cys with rapid responsiveness, imaging living cells and intact tissues with high contrast and brightness at a depth of 150 μm. The two-photon action cross section (Φσmax) of ASMI is 65.2 GM, corresponding to an excitation wavelength (λex) of 740 nm.

Lyso-MPCB is a two-photon fluorescent probe used for lysosomal pH detection and autophagy monitoring. Lyso-MPCB integrates a benzimidazole pH-responsive group and a morpholine lysosome-targeting group, enabling specific localization to lysosomes. The fluorescence properties of Lyso-MPCB change with protonation, exhibiting blue fluorescence under alkaline conditions and green fluorescence under acidic conditions .

DMA-SiRd is a fluorescent probe that can be used for crosstalk-free dual-channel imaging of lipid droplets and mitochondria, mapping of lipid microenvironment heterogeneity, and imaging of lipid droplet-mitochondria interactions. DMA-SiRd has two imaging channels: Ex/Em = 633/650-750 nm and Ex/Em = 546/570-620 nm, with two-photon excitation wavelengths of 1040 nm and 1200 nm for brain imaging. DMA-SiRd can be applied to the research of atherosclerosis .

MBCB is a two-photon Fluorescent probe for dual-detection of mitochondrial SO₂ derivatives and viscosity. For SO₂ derivatives detection, the probe utilizes a Michael addition mechanism: nucleophilic addition of SO₂ derivatives to the C=C bond between the carbazole skeleton and 3-methylbenzothiazolium moiety destroys the strong intramolecular charge transfer (ICT) system between these groups, while enhancing the weak ICT system between the benzothiazole group and carbazole framework; this causes the red emission at 600 nm to decrease and the blue emission at 434 nm to increase, creating a ratiometric response based on the I₄₃₄ₙₘ/I₆₀₀ₙₘ intensity ratio. For viscosity detection, in low-viscosity environments, steric hindrance creates a twisted ICT (TICT) system with weak fluorescence, while in high-viscosity environments, intramolecular rotation is blocked, the TICT state is disrupted, and the strong ICT system is recovered, leading to a strong red emission at 567 nm with negligible change to the short-wavelength emission at 415 nm, creating a ratiometric response based on the I₅₆₇ₙₘ/I₄₁₅ₙₘ intensity ratio that has a logarithmic linear relationship with viscosity. The probe has excitation/emission wavelengths of Ex/Em = 351/434, 600 nm for SO₂ derivatives detection and Ex/Em = 351/567 nm for viscosity detection, with two-photon excitation at 740 nm for bioimaging; it also exhibits good mitochondrial targeting ability with a Pearson's colocalization coefficient of 0.93 when paired with Mito-Tracker Green. The probe shows high sensitivity and selectivity for SO₂ derivatives, has low cell cytotoxicity, and can be applied to detect exogenous/endogenous HSO₃⁻ in living cells and in vivo, as well as visualize mitochondrial viscosity changes induced by nystatin[1].