Figure 2.

Different generations of PSs widely used in various cancer cell types. Currently developed PSs can be divided into first-generation PSs, second-generation PSs, and third-generation PSs. The description is provided as follows: ● chemical name (abbreviation)(trade name is indicated with^®, and excitation wavelength is indicated in “nm“ during clinical PDT procedure). If information is not available, this is indicated with (-). λ in PTW represents the typical wavelength at which absorption of photosensitizer occurs to penetrate into tissues (PTW, λ > 600 nm), and ε represents the absorption rate at PTW.