ct9b00533_si_001.pdf (412 kB)
Photophysics of BODIPY-Based Photosensitizer for Photodynamic Therapy: Surface Hopping and Classical Molecular Dynamics
Version 2 2019-08-22, 19:03
Version 1 2019-08-21, 14:36
journal contribution
posted on 2019-08-22, 19:03 authored by Marek Pederzoli, Mirza Wasif Baig, Mojmír Kývala, Jiří Pittner, Lukasz CwiklikHalogenated
BODIPY derivatives are emerging as important candidates
for photodynamic therapy of cancer cells due to their high triplet
quantum yield. We probed fundamental photophysical properties and
interactions with biological environments of such photosensitizers.
To this end, we employed static TD-DFT quantum chemical calculations
as well as TD-DFT surface hopping molecular dynamics on potential
energy surfaces resulting from the eigenstates of the total electronic
Hamiltonian including the spin–orbit (SO) coupling. Matrix
elements of an effective one-electron spin–orbit Hamiltonian
between singlet and triplet configuration interaction singles (CIS)
auxiliary wave functions are calculated using a new code capable of
dealing with singlets and both restricted and unrestricted triplets
built up from up to three different and independent sets of (singlet,
alpha, and beta) molecular orbitals. The interaction with a biological
environment was addressed by using classical molecular dynamics (MD)
in a scheme that implicitly accounts for electronically excited states.
For the surface hopping trajectories, an accelerated MD approach was
used, in which the SO couplings are scaled up, to make the calculations
computationally feasible, and the lifetimes are extrapolated back
to unscaled SO couplings. The lifetime of the first excited singlet
state estimated by semiclassical surface hopping simulations is 139
± 75 ps. Classical MD demonstrates that halogenated BODIPY in
the ground state, in contrast to the unsubstituted one, is stable
in the headgroup region of minimalistic cell membrane models, and
while in the triplet state, the molecule relocates to the membrane
interior ready for further steps of photodynamic therapy.