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Long-wavelength emission with high contrast toward species of interest is highly desired for fluorescence imaging in living objects. Herein, we proposed an exquisite enzyme-regulated "aggregation-induced emission (AIE) and intramolecular charge transfer (ICT)" strategy to optimize the signal-to-noise ratio for highly sensitive detection of enzymes. Benefiting from the synergistic effect, probes ABT-Gal-1 and ABT-Gal-2 exhibited faint background signals but dramatically enhanced near-infrared fluorescence upon exposure toward β-galactosidase (β-gal). Notably, both probes could be accessible in aqueous media. Preferably, the fluorescence intensity of ABT-Gal-1 exhibited a satisfactory linear relationship in the wide concentration range of 0.5–30 U/L with a very low detection limit to 0.24 U/L. Further, by monitoring endogenous β-gal in ovarian cancer cells, a precious merit of resistance to multiple washes was identified, which was facilitated by the nanoaggregate formation in situ upon activation. This work proposes a guiding strategy for manipulating various lighting mechanisms to develop attractive probes and, equally importantly, it provides an ideal practical tool for elucidating the biological role of β-gal in biological scenarios. [Display omitted] • Comprehensive insights into the ICT and AIE characteristic of amino-type ESIPT-based fluorophore are proposed. • An exquisite enzyme-regulated "AIE and ICT" strategy to optimize the signal-to-noise ratio is reported for the first time. • Debut of activatable AIE probe for β-gal with emission in near-infrared window is well presented. • Probe ABT-Gal-1 was allowed in aqueous media with the lowest detection limit (0.24 U/L) compared with reported probes. • The nanoaggregation-allowed probe was firstly disclosed with resistance to multiple washes during cell imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • BODIPY derivatives with triarylamine (TPA) moieties on their 3-, 5-, or 8-positions showed near infrared emission, large Stokes shifts and two-photon absorptions. • These triarylamine (TPA) modified BODIPYs showed aggregation-induced emission (AIE) properties. • These BODIPYs all can be used in tracking the dynamic behaviors of lipid droplets or lysosomes in living cells. A series of five BODIPY derivatives with triarylamine (TPA) moieties on their 3-, 5-, or 8-positions were reported, which showed wide-range fluorescence emissions across red and near infrared regions in their aggregation states. The influences of numbers and substituted positions of TPA groups on the optical and aggregation-induced emission (AIE) properties of these BODIPYs as well as organelle-specific imaging in live cells were investigated. The TPA groups installed at 3-/5-positions of BODIPY could effectively enlarge the conjugated system and red-shift the absorption and emission bands (λ em max up to 815 nm). In contrast, the TPA group linked to 8-position of BODIPY core has little contribution to decrease the HOMO-LUMO energy gap. Importantly, regardless the substitution positions of TPA groups, all these TPA-substituted BODIPYs (BTs) showed remarkable AIE performance and possessed high molar extinction absorption (up to ∼ 63000 M−1 cm−1), two-photon absorption (up to 171 GM at 870 nm), and large Stokes shifts. The BODIPY with one TPA group (BT1 and FBT1) showed lipid droplets-specific localization while BODIPY with two and three TPA groups (BT2 , BT3 and FBT2) preferred to enrich in lysosomes. These BODIPYs all have been successfully used in tracking the dynamic behaviors of lipid droplets or lysosomes in living cells. Furthermore, BT1 and FBT1 can quantitatively detect the overexpression of lipid droplets, and BT3 has been successfully used to observe lysosomes behaviors of lipophagy process in living cells. This work systematically studied the influence of the number and position of TPA units on the optical properties and AIE-activities of BODIPYs, which not only enriched the BODIPY-based AIE NIR probes for organelle-specific imaging in live cells, but also provided a practical strategy for the effective construction of organic dyes with NIR AIE activity. [ABSTRACT FROM AUTHOR]