Table 5.

Biophysical properties of two-photon–suitable probes in the diseased brain: peak wavelength of two-photon action cross-section (λ _2PA) ; peak two-photon action cross-section (σ₂φ) ; fluorescence wavelength (λ _fluo). Probes discussed in the text are in bold.

Probe	λ2PA [nm]	σ2φ [GM]	λfluo [nm]	Comment	Reference
Calcofluor White	590		430b	Cellulose and chitin binding (identification of fungi and yeast)	Figure 5B in (Trägårdh et al. 2015)
DCIP-1 (in PBS / bound to amyloid- β aggregates)	900	118	675 / 635	Amyloid-β plaques, penetrates BBB	Figure S7 in (Zhu et al. 2017)
Gatifloxacin	700		~510	Fluoroquinolone antibiotics	Figure 1A in (Lee et al. 2016)
MeO-X04 (in PBS / EtOH)	720	10 / 75	452 / 444	Amyloid-β plaques (Klunk et al. 2002)	– (Table S1) (Heo et al. 2013)
MNAH	820		536	Imaging of mitochondrial singlet oxygen	– (Liu et al. 2016)
Moxifloxacin	700		~530	Fluoroquinolone antibiotics	Figure 1A in (Lee et al. 2016)
PIB (in PBS / EtOH)	740	45 / 40	431 / 417	Amyloid-β plaques	– (Table S1) (Heo et al. 2013)
SAD1 (in PBS / EtOH)	750	10 / 170	497 / 465	Amyloid-β plaques	– (Table S1) (Heo et al. 2013)

^a: calculated from the σ₂ and φ values

^b: data from commercial provider