Morphological Response in Cancer Spheroids for Screening Photodynamic Therapy Parameters.

Photodynamic therapy (PDT) is a treatment which uses light-activated compounds to produce reactive oxygen species, leading to membrane damage and cell death. Multicellular cancer spheroids are a preferable alternative for PDT evaluation in comparison to monolayer cell cultures due to their ability to better mimic avascular tumour characteristics such as hypoxia and cell-cell interactions, low cost, and ease of production. However, inconsistent growth kinetics and drug responsiveness causes poor experimental reproducibility and limits their usefulness.

Low-Fluence Photodynamic Therapy Parameter Screening Using 3D Tumor Spheroids Shows that Fractionated Light Treatments Enhance Phototoxicity.

The evaluation of novel photosensitizers (PSs) for photodynamic therapy (PDT) is difficult due to the limitations of two-dimensional cell culture and multiple parameters (dose, light intensity, uptake time), which complicate progression to experiments and clinical translation. Three-dimensional (3D) cell culture models like multicellular cancer tumor spheroids (MCTS) show great similarities to avascular tumor conditions, improving the speed and accuracy of screening novel compounds with various treatment combinations. In this study, we utilize C8161 human melanoma spheroids to screen PDT treatment combinations using protoporphyrin IX (PpIX) and drug-loaded carbon dot (CD) conjugates PpIX-CD and PpIX@CD at ultralow fluence values (<10 J/cm).

Carbon dot-protoporphyrin IX conjugates for improved drug delivery and bioimaging.

Photodynamic therapy (PDT) uses photosensitisers such as protoporphyrin IX (PpIX) to target tumours via the release of toxic singlet oxygen when irradiated. The effectivity of the treatment is limited by the innate properties of the photosensitizers; they typically exhibit inefficient accumulation in target tissue and high dark toxicity. Carbon dots (CDs) are biocompatible fluorescent nanoparticles which can improve PpIX cellular uptake and solubility.