Federal Institute of Parana 1 article published in JoVE Biochemistry An In-House-Built and Light-Emitting-Diode-Based Photodynamic Therapy Device for Enhancing Verteporfin Cytotoxicity in a 2D Cell Culture Model Isadora da Silva Zanzarini1, Gustavo Barbosa1, Larissa de Oliveira Prado1, Ingrid Fatima Zattoni1, Gustavo Da Paz1, Ademir Luiz do Prado2,3, Waldemar Volanski2, Marcos Dinís Lavarda3, Fabiane Gomes de Moraes Rego2, Geraldo Picheth2, Vivian Rotuno Moure1, Glaucio Valdameri1 1Graduate Program in Pharmaceutical Sciences, Laboratory of Cancer Drug Resistance, Federal University of Parana, 2Graduate Program in Pharmaceutical Sciences, Federal University of Parana, 3Federal Institute of Parana Here, we describe a novel, simple, and low-cost device to successfully perform in vitro photodynamic therapy (PDT) assays using two-dimensional HeLa cell culture and verteporfin as a photosensitizer.