Triplet Fusion Mediated Bio-Sensing on DNA Origami
The proposed combination of triplet fusion upconversion and DNA origami structures is a promising endeavor to creation of efficient, bio-compatible, feasibly manufactured, and false-positive free bio-sensing systems.
Triplet fusion (TF) upconversion (UC) is a process which converts two low-energy photons via triplet states to the one of a higher energy in organic annihilator/sensitizer systems. TF-UC is advantageous to other UC processes due to its function under incoherent low-density excitations bringing opportunity for applications in photovoltaics, photocatalysis, targeted drug delivery and bio-sensing. The proposed project is focused on combination of TF-UC and DNA origami fields to assemble efficient, bio-compatible, feasibly manufactured, and false-positive free bio-sensing systems. TF-UC is a collisional, intermolecular distance dependent process due to the Dexter transfer nature (~1 nm) of triplet states, thus requiring precise positioning of the molecules for TF to occur. The 3D DNA origami structures may be utilized to localize the annihilator/sensitizer chromophores on DNA sequence which provide some flexibility with complementary spacers. As the TF process may only occur at a certain molecular distance and orientation of annihilators, it can be achieved by closing the 3D DNA origami structures with attachment of target antigen or protein structures. Once the 3D DNA origami structure is closed, the annihilators are positioned in a way suitable for TF to occur resulting in visible emission detected by a single molecule fluorescence system. Even with high attained TF-UC quantum yields (up to 28% out of 50%), its emission intensity in a certain direction can be further improved by employing the plasmon-resonance effect with addition of gold or silver nanoparticles onto DNA structure. Nonetheless, a wide-field fluorescence microscopy may be utilized to quantitatively determine number of antigen or protein structures present in the sample. To conclude, the proposed combination of TF-UC and DNA origami fields is a promising endeavor for creation of novel and efficient bio-sensing devices.
Lukas Naimovičius, Lindau Alumnus 2022
Institute of Materials Science of Barcelona, Spain