Bismuth doped carbon nanospheres conjugated to boronated porphyrins for photodynamic therapy

Novel 4- (5,10,15)-tris-boronphenyl-20-(4-formylphenoxy) porphyrin (complex 1) and its Zn-metalated derivative (complex 2) were synthesized and conjugated to bismuth doped carbon nanospheres (BiCNS) through non-covalent bonds (π-π). The conjugation of BiCNS to porphyrin complexes enhanced the singlet oxygen production of porphyrin complexes, as it was observed that porphyrin complex 1 gave a singlet oxygen quantum yield (Φ_∆) value of 0.17 and complex 2 gave Φ_∆ of 0.23, and upon conjugation with BiCNS the Ф_∆ values increased to 0.52 and 0.67, respectively. Photodynamic therapy (PDT) studies were performed against MDA-MB-231 breast cancer cell line using these complexes and their conjugates and it was observed that BiCNS conjugates resulted in enhanced PDT activity when compared to CNS conjugates. Conjugates 2-CNS, and 2-BiCNS at the concentration of 100 µg/mL they resulted with cell viabilities of 28.43 and 26.82 %, respectively.