Nanoclusters for Cancer Therapy: Assesment of Their Reactive Oxygen Species Generation and Stability
Chemistry , Nanomaterials , Photochemistry , Materials , Photodynamic Therapy
Scientists are continually searching for new ways to improve the detection and treatment of disease. Recently, metal nanoclusters have emerged as materials that can be used to identify and treat cancer. Nanoclusters or "clusters" are small arrangements of metal atoms protected by an exact number of ligands. Clusters have unique properties that make them useful for a variety of biomedical applications including bioimaging, photodynamic therapy, and radiotherapy. Herein, nanoclusters are explored specifically for their use in photodynamic therapy. Photodynamic therapy is a type of cancer therapy that uses light to activate drugs known as photosensitizers inside the body. Nanoclusters can act as photosensitizers because they absorb light and use this energy to generate reactive oxygen species, resulting in targeted cancer cell death. To be an effective photosensitizer, clusters must have long-lived excited states that can interact with oxygen to produce reactive oxygen species. This interaction between the excited state of nanoclusters and oxygen remains relatively unexplored. Additionally, numerous studies have investigated nanoclusters in cell and animal models for therapy, measuring cell uptake, toxicity, and efficacy. However, missing from the current body of work is information on how the structure and properties of nanoclusters are affected by physiological conditions. This is critical for the advancement of nanoclusters, since the properties of clusters are highly structure-dependent and clusters are sensitive to their conditions. In this thesis: 1) Our understanding of nanoclusters and their interaction with oxygen is furthered by probing their reactive oxygen species production and studying their excited state dynamics. 2) A series of thiol protected gold and silver nanoclusters are studied under physiological conditions. Their optical properties are monitored as a metric of their stability, which indicated that many nanoclusters degrade in these conditions.