Symmetry breaking charge transfer leading to charge separation in a far-red absorbing bisstyryl-BODIPY dimer.

Symmetry breaking charge transfer is one of the important photo-events occurring in photosynthetic reaction centers that is responsible for initiating electron transfer leading to a long-lived charge-separated state and has been successfully employed in light-to-electricity converting optoelectronic devices. In the present study, we report a newly synthesized, far-red absorbing and emitting BODIPY-dimer to undergo symmetry-breaking charge transfer leading to charge-separated states of appreciable lifetimes in polar solvents. Compared to its monomer analog, both steady-state and time-resolved fluorescence originating from the S1 state of the dimer revealed quenching which increased with an increase in solvent polarity. The electrostatic potential map from DFT and the time-dependent DFT calculations suggested the existence of a quadrupolar type charge transfer state in polar solvents, and the singlet excited state to be involved in the charge separation process. The electrochemically determined redox gap being smaller than the energy of the S1 state supported the thermodynamic feasibility of the envisioned symmetry-breaking charge transfer and separation. The spectrum of the charge-separated state arrived from spectroelectrochemical studies, revealing diagnostic peaks helpful for transient spectral interpretation. Finally, ultrafast transient pump-probe spectroscopy provided conclusive evidence of diabatic charge separation in polar solvents by far-red pulsed laser light irradiation. The measured lifetime of the final charge-separated states was found to be 165 ps in dichlorobenzene, 140 ps in benzonitrile, and 43 ps in dimethyl sulfoxide, revealing their significance in light energy harvesting, especially from the less-explored far-red region.

Poly(Acrolein-co-ß-Cyclodextrin) Functionalized Magnetic Nanoparticles for Selective CD45-Positive Cells Capturing.

In this work, a new magnetic nanocomposite was prepared for the specific isolation of CD45 positive cells. Acrolein (AC) and acrylated ß-cyclodextrin (ACD) were used as monomers in order to polymerize on the surface of Fe3O4 magnetic nanoparticles (MNPs) via surface initiated radical polymerization. Polyacrolein-ß-CD (PACD) functionalized Fe3O4 MNPs (Fe3O4@PACD) was achieved and subsequently, fluorescein conjugated IgG anti-human CD45 was immobilized onto Fe3O4@PACD. Antibody conjugation onto the latter nanocomposite was accomplished according to IgG encapsulation in cyclodextrin cavity and Schiff base formation between aldehyde groups of MNPs and primary amines of antibody. The characterization analysis of the bare Fe3O4, Fe3O4@PACD nanocomposite, and Fe3O4@PACD-Ab were investigated using XRD, VSM, FT-IR, H-NMR, TGA, SEM, TEM, and flow cytometry techniques. The results showed that the antibody has been successfully immobilized onto Fe3O4@PACD. Moreover, the fabricated nanocomposite was used for selective capturing of CD45+ cells among other peripheral blood mononuclear cells (PBMCs). The results of TEM and fluorescence microscopy confirmed the ability of the conjugated system for efficient cell capturing.