Microwave-assisted direct synthesis of BODIPY dyes and derivatives

Synthesis of BODIPYs using organoindium reagents and survey of their cytotoxicity and cell uptake on nervous system cells

In this study, a series of BODIPY dyes were synthesized, containing various substituents at meso position. Further functionalization of the BODIPY framework at C2 and C2-C6 position(s) by palladium-catalysed cross-coupling reactions using organoindium reagents (R3In) was efficiently assessed, starting from C2(6)-halogenated BODIPYs, and their optical properties were measured. The cytotoxicity of BODIPY dyes on SH-SY5Y neuronal cells by MTT assay showed that those compounds bearing thien-2-yl and benzonitrile moieties at meso position, exhibited great efficiency in maintaining cell viability under all tested conditions (up to 50 µM for 24 h and 48 h). Furthermore, nanoliposomal encapsulation of a hydrophobic BODIPY, incorporating bis(trifluoromethyl)phenyl substituents at C2 and C6 positions, through the lipid-extrusion method was addressed. The liposomes exhibited spherical shape as observed in cryo-TEM image, with average particle size of 120 nm (average PdI 0.05) and Zeta potential 54.69 mV by DLS measurements. Simple incubation of gliobastoma U-87 cells with prepared liposomes led to efficient internalization, and visualization of brightness BODIPY in cytoplasm using fluorescence confocal microscopy, demonstrating encapsulation enhance biocompatibility of the hydrophobic BODIPY as preliminary approximation for further biomedical applications.

A benzofuran-[b]-fused BODIPY trimer enabled by dual TBET and PET mechanisms for high-performance two-photon fluorescence imaging

A benzofuran-[b]-fused BODIPY trimer has been efficiently synthesized, featuring a unique structural design that harmoniously integrates TBET (through bond energy transfer) and PET (photo-induced electron transfer) mechanisms. This trimer boasts exceptional optical properties, including a large pseudo-Stokes shift of 100 nm, an impressive fluorescence quantum yield (ΦFL = 0.931), an outstandingly high extinction coefficient (182 100 M-1 cm-1), a remarkable FEF (fluorescence enhancement factors, 22.4-fold) values as well as exhibiting AIE (aggregation-induced emission) activity, and has been successfully utilized in two-photon fluorescence imaging of live-cell lipid droplets.

A toolbox for enzymatic modification of nucleic acids with photosensitizers for photodynamic therapy

Photodynamic therapy (PDT) is an approved cancer treatment modality. Despite its high efficiency, PDT is limited in terms of specificity and by the poor solubility of the rather lipophilic photosensitizers (PSs). In order to alleviate these limitations, PSs can be conjugated to oligonucleotides. However, most conjugation methods often involve complex organic synthesis and result in the appendage of single modifications at the 3'/5' termini of oligonucleotides. Here, we have investigated the possibility of bioconjugating a range of known PSs by polymerase-mediated synthesis. We have prepared a range of modified nucleoside triphosphates by different conjugation methods and investigated the substrate tolerance of these nucleotides for template-dependent and -independent DNA polymerases. This method represents a mild and versatile approach for the conjugation of single or multiple PSs onto oligonucleotides and can be useful to further improve the efficiency of the PDT treatment.

Synthesis and Photophysical Properties of β-Alkenyl-Substituted BODIPY Dyes by Indium(III)-Catalyzed Intermolecular Alkyne Hydroarylation

A new atom-economical synthesis of β-alkenyl-substituted BODIPYs via indium(III)-catalyzed intermolecular alkyne hydroarylation with meso-substituted BODIPYs is described. While catalysis with InI3 allows the double β-functionalization of BODIPY, resulting in regioselectively branched β,β'-disubstituted alkenyl BODIPYs, catalytic InCl3 enables the formation of linear β-substituted alkenyl BODIPYs. Subsequent In(III)-catalyzed intermolecular alkyne hydroarylation allows the synthesis of unsymmetrical push-pull BODIPY derivatives. Therefore, indium catalysis offers complementary regioselectivity in good chemical yields and functional group tolerance. The resulting BODIPY dyes displayed bathochromically shifted absorption and emission according to the electron-nature of the substituents in the alkenyl moiety with high molar extinction coefficients (ε up to 88,200 M-1 cm-1) and quantum yields (0.14-0.96).