Quantum dots in photodynamic therapy

Colloidal Quantum Dots as an Emerging Vast Platform and Versatile Sensitizer for Singlet Molecular Oxygen Generation

“…Subsequently, the exciton is relaxed back, releasing the energy through various pathways: phononassisted relaxation, exciton radiative recombination, nonradiative decay due to surface states/traps, auger recombination, electronic energy transfer to the vibrational energy level of ligands, etc. 42,51,53,73,75 The optoelectronic properties of QDs originate from sizedependent quantum confinement effects; therefore, changing the size and shape of the PL emission can be predictably tuned over a wide wavelength range (Figure 2a,b), such as from the UV−vis to NIR-I (700−900 nm) and NIR-II (1000−1700 nm) regions. 14,20,64,65,72,73 Additionally, QDs also present upconversion optical features by converting multiple low-energy photons into a single high-energy photon.…”

“…The term FRET is named after Theodor Forster, a theoretical physicist who proposed an equation to quantify the energy transfer efficiency from an energy donor (D) to an acceptor (A) in 1948. FRET is a nonradiative energy transfer process from an excited state donor (D*) to a proximal ground state acceptor (A) through a long-range transition dipole moment, producing a donor in the ground state (D) and an acceptor in the excited state (A*), 75,120 shown by the following mechanism (i):…”

“…In another strategy, QDs are linked to some other organic PS by electrostatic interaction or covalent bonding, producing a QDs−PS hybrid nanostructure (Figure 5c−e) which operates as an energy donor fluorophore (QDs) and ground state acceptor molecule (PS). 20,43,[55][56][57][58][59][60]75 Since direct excitation of a PS triplet state is spin forbidden, the PS singlet excited state undergoes ISC or singlet fission to produce triplet excited states. 120 Alternately, molecular triplet states are populated by strategically placing the bandgap of QDs smaller than the singlet excited state of the acceptor but greater than its triple excited state 19,58 (Figure 5c).…”

“…Owing to its strong oxidizing nature, 1 O 2 exhibits high reactivity toward electronrich organic substrates such as olefins, dienes, and polycyclic aromatic compounds. 4,38 It is shown as one of the major cytotoxic species implicated in photodynamic therapy (PDT) of cancerous tissues [5][6][7]13,14,17,42,53,74,75 and diseases such as porphyria 74 and cataracts. 76 Singlet oxygen is aslo used as an effective tool to inactivate or kill the pathogens, i.e., bacteria, viruses, and fungi.…”

“…Owing to its strong oxidizing nature, 1 O 2 exhibits high reactivity toward electron-rich organic substrates such as olefins, dienes, and polycyclic aromatic compounds. , It is shown as one of the major cytotoxic species implicated in photodynamic therapy (PDT) of cancerous tissues − ,,,,,,, and diseases such as porphyria and cataracts . Singlet oxygen is aslo used as an effective tool to inactivate or kill the pathogens, i.e., bacteria, viruses, and fungi. ,, It reacts readily with electron-rich/unsaturated substrates such as DNA, RNA, unsaturated fatty acids, and cholesterol and protein/amino acids such as cysteine, histidine, methionine, tryptophan, and tyrosine methionine, forming endoperoxides, hydroperoxides, and dioxetanes. ,− ,,,,− Thus, the damage induced to biomolecules leads to a cascade of reactions culminating in several biological events: (1) necrosis/or apoptosis of tumor cells; (2) destruction of tumor microvasculature and platelet aggregation; and (3) stimulation of autoimmune and inflammatory responses that eliminate the remaining tumor cells. , …”