Evaluation of Photodynamic Therapy Using AuNPs@Ce6 in 3D Cultures of Triple-Negative Breast Cancer

Conventional cancer treatments have limited efficacy for aggressive subtypes such as triple-negative breast cancer (TNBC), which points to the importance of new therapeu- tic strategies. Functionalized nanoparticles in conjunction with photodynamic therapy (PDT) represent a promising alternative. Additionally, 3D cell culture emerges as a more effective model, as it better replicates the structural and functional characteristics of the tumor microenvironment. In this study, 3D microtumors of TNBC were cultivated and treated with PDT using gold nanoparticles functionalized with Chlorin e6 (AuNPs@Ce6). Cell viability was assessed using the MTT colorimetric assay, combined with histological analysis using hematoxylin-eosin staining. The MTT assay and histological evaluation of the 3D spheroids demonstrated that PDT with AuNPs@Ce6 effectively reduced cell viability and induced necrotic morphological changes, while maintaining biocompatibility with the non-irradiated control group. These findings reinforce the potential of this ap- proach for further investigation in TNBC models and underscore the value of 3D cultures as physiologically relevant and ethical alternatives to animal testing.