Rose Bengal-conjugated gold nanoparticles ;: quantification of singlet oxygen generation in photodynamic therapy

Photodynamic therapy (PDT) is an advanced novel methodology for the treatment of cancers using photosensitizers (PSs) which upon irradiating light generate cytotoxic singlet oxygen (¹O₂) and kills cancer cells. The utilization of photosensitizers has some restrictions, like low coefficient of extinction, low ¹O₂ generation efficiency and cannot be used for treating deep-seated tumours. Nanoparticles (NPs) have various properties that can be applied in PDT to overcome the limitations of PSs. The main aim of this work is, therefore, to enhance the ¹O₂ generation efficiency of the photosensitizer Rose Bengal (RB) by conjugating it with the Gold nanoparticles (AuNPs). The quantitative measurement of ¹O₂ generation is carried out on photosensitizer RB, AuNPs, and Au-NPs conjugated RB (AuRB). The fluorescence probe Singlet Oxygen Sensor Green (SOSG) was used to detect the ¹O₂. In a systemic study, the dependence of fluorescence on AuRB conjugation with different PS concentrations and the light-irradiation time for ¹O₂ generation are performed. Finally, the singlet oxygen quantum yield (SOQY) measurements are carried from the calculation of the rate of reaction and discussed. The results of the project state the improvement in ¹O₂ generation efficiency of PS on conjugation with the NPs. The successful NP-PS conjugation and high SOQY give the motivation for further studies on the development of the new photosensitizer drugs to treat the cancer cells.