Photodynamic therapy is a proven way to treat solid tumours and other lesions that are easy to get to. Light therapy, which uses a photosensitizing substance and light to treat illness, has been around for more than a century, but our knowledge of the field as a whole has grown a lot in the last few years. The production of reactive oxygen species, especially singlet oxygen, which happens during photosensitized processes, can damage biological macromolecules like membrane lipids and proteins. In order to do this, photosensitizers are chemicals that make a lot of 1O2. Even though photofrins are the most common type of photosensitizer used in practise, scientists are now looking into other, possibly more effective sensitizers. White light that had been changed with filters used to be the norm, but now lasers and more advanced light-emitting diodes are used instead. But dosimetry is still a problem because it is hard to figure out the best treatment conditions for an approach that involves fine- tuning several variables, such as the sensitizer and light doses and the time between the drug and the light, and because the skin is sensitive to light and has low selectivity. Recently, however, the phenomenon of photo-activation has come up as a way to get around these problems and make the idea more useful. In this case, it has been shown that exposing chromophores to light creates new, small, biologically active molecules. The goal of this study was to give a broad overview of photodynamic therapy and shed light on some of the biggest challenges and most promising new directions for developing it.

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