Executive Summary : | For several decades now, cancer has been a disease of serious concern. Therefore, considerable research has been devoted worldwide to the treatment of cancer. Among the different treatment modalities, photoinduced cancer therapies have been garnering maximum attention owing to its non-invasive nature and spatio-temporal control over drug action, and among photoinduced therapies, photodynamic therapy (PDT) is one of the most prominent. PDT involves the excitation of a photosensitizer to its triplet excited state, wherefrom it can transfer energy to ground-state molecular oxygen, affording excited singlet oxygen species, which in turn cause apoptosis. One of the major concerns regarding cancer treatment is delayed diagnosis; the detection of specific biomarkers is essential for early cancer diagnosis. Organic compounds with boiling points of 50–250 °C are categorized as volatile organic compounds (VOCs), such as formaldehyde, ethanol, and methanol, which are found in large excess in samples of breath, blood, saliva, and urine of several early-stage cancer patients. Thus, developing a probe for such VOC detection will be beneficial for early-stage cancer detection. Significant research is ongoing in the field of near-infrared (NIR) fluorescent probes for biological applications because of their deep tissue penetration ability and their ability to exhibit distinct fluorescence properties due to various energy transfer processes like photoinduced electron transfer (PET), fluorescence resonance energy transfer (FRET), aggregation-induced emission (AIE), etc. These probes can show dual fluorescence before and after interaction with the analyte. Hence, developing an NIR-active fluorescent probe for VOC detection can be helpful in the field for cancer treatment. It will be even more advantageous if the probe itself can show PDT activity. Thus, in this proposal, I aim to develop new NIR probes for the detection of VOCs in early-stage cancer patients and the simultaneous PDT activity. As potential dual-purpose VOC detectors, I intend to utilize some small-organic-molecule-based probes consisting of suitable donor-π-acceptor combinations that can render efficient energy transfer processes, enabling the dual fluorescent character. Of late, fluorescent organic polymers (FOPs) have shown prominent results in the field of healthcare owing to their biocompatibility, micelle formation ability, etc. Such FOPs can be used to detect VOCs via H-bonding or π-stacking, which in turn can lead to prominent AIE from the probes. Thus, the present proposal focuses on developing small-molecule- and FOP-based NIR probes for the dual action of VOC detection and simultaneous PDT activity for early-stage cancer diagnosis and treatment. |