Therapeutic potential of hybridized nanoparticles embedded with hydrophobic and hydrophilic metallic elements: An optical thermometry approach

Biophotonics is an interdisciplinary field combining physics, chemistry, biology, and optics to explore light-tissue interactions for diagnostic and therapeutic purposes. It encompasses techniques such as spectroscopy, microscopy, biomedical imaging, and light-based therapies. Among these, photodynamic therapy (PDT) has gained prominence as a minimally invasive cancer treatment. PDT relies on the activation of photosensitizers (PSs) by specific light wavelengths in the presence of molecular oxygen, producing cytotoxic reactive oxygen species (ROS) that induce tumour cell death. However, conventional PSs face limitations including poor solubility, low tumour selectivity, photobleaching, and potential adverse immune responses. Recent advances in nanotechnology have introduced nanoparticle-based drug delivery systems to overcome these challenges. This review critically examines the role of nanotechnology in cancer theranostics, with a focus on green-synthesized nanomaterials. A systematic literature search was performed across major databases, including Scopus, Web of Science, and PubMed, targeting peer-reviewed studies that report on nanoparticle synthesis, characterization, and applications in PDT and photodynamic diagnosis (PDD). The review discusses various nanoparticle synthesis methods including chemical, physical, and biologically mediated (green) approaches. Furthermore, the advantages and limitations of nanoparticle-based delivery systems are critically evaluated, with emphasis on challenges related to reproducibility, scalability, long-term toxicity, biodistribution, and clinical translation. Overall, this review highlights the integration of biophotonics and green nanotechnology as a promising and sustainable approach for improving cancer diagnosis and therapy, while identifying critical gaps that must be addressed to support their development as viable alternatives to conventional treatments.