Photodynamic therapy (PDT) using TiO 2 nanoparticles has become an important alternative treatment for different types of cancer due to their high photocatalytic activity and high absorption of UV-A light. To potentiate this treatment, we have coated commercial glass plates with TiO 2 nanoparticles prepared by the sol-gel method (TiO 2 -m), which exhibit a remarkable selectivity for the irreversible trapping of cancer cells. The physicochemical properties of the deposited TiO 2 -m nanoparticle coatings have been characterized by a number of complementary surface-analytical techniques and their interaction with leukemia and healthy blood cells were investigated. Scanning electron and atomic force microscopy verify the formation of a compact layer of TiO 2 -m nanoparticles. The particles are predominantly in the anatase phase and have hydroxylterminated surfaces as revealed by Raman, X-ray photoelectron, and infrared spectroscopy, as well as X-ray diffraction. We find that lymphoblastic leukemia cells adhere to the TiO 2 -m coating and undergo amoeboid-like migration, whereas lymphocytic cells show distinctly weaker interactions with the coating. This evidences the potential of this nanomaterial coating to selectively trap cancer cells and renders it a promising candidate for the development of future prototypes of PDT devices for the treatment of leukemia and other types of cancers with non-adherent cells.

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Coatings of modified TiO2 nanoparticles (TiO2-m) have been shown to effectively and selectively trap non-adherent cancer cells, with an enormous potential for applications in photodynamic therapy (PDT). Leukemia cells have a remarkable affinity for TiO2-m coatings, adhering to the surface by membrane structures and exhibiting morphologic characteristics of amoeboid locomotion. However, the details of the cell–substrate interaction induced by the TiO2-m coating remain elusive. With the aim to obtain a better understanding of this phenomenon, leukemia cell adhesion to such coatings was characterized by atomic force microscopy (AFM) for short contact times up to 60 min. The cell and membrane morphological parameters mean cell height, contact area, cell volume, and membrane roughness were determined at different contact times. These results reveal cell expansion and contraction phases occurring during the initial stage of adhesion. Subsequently, the leukemic cells reach what appears to be a new resting state, characterized by pinning of the cell membrane by TiO2-m nanoparticle aggregates protruding from the coating surface.

La terapia fotodinámica (PDT) se ha convertido en una alternativa importante para el tratamiento de diferentes tipos de cáncer, debido a sus grandes ventajas frente a métodos convencionales. En este campo, las nanopartículas de TiO2 son uno de los fotosensibilizadores más ampliamente estudiados, por su alta actividad fotocatalítica, alta absorción de radiación UVA y alta biocompatibilidad. Aunque hay varios estudios satisfactorios relacionados con el tratamiento PDT, usando nanopartículas de TiO2, para diferentes tipos de células cancerosas adherentes, existen muy pocos reportes de esta metodología aplicada para células no adherentes, debido a los retos relacionados con el volumen de tratamiento y el alcance de la radiación. Para afrontar este reto, nanopartículas de TiO2 modificadas (TiO2-m) se depositaron sobre substratos de vidrio para estudiar el efecto citotóxico de PDT sobre células Molt4, células no adherentes, usando estos recubrimientos. Se comprobó la formación de recubrimientos uniformes sobre los substratos mediante la desviación estándar de la transmitancia en el rango UVA, en diferentes puntos. Se realizaron diferentes pruebas experimentales de PDT de células Molt4 sobre recubrimientos de TiO2-m y el efecto citotóxico de los tratamientos fue evaluado por medio de concentración LDH. Los resultados demostraron la posibilidad de generar un efecto citotóxico de células cancerosas no adherentes con solo 20 min de contacto y 40 min de radiación UVA. Este resultado es el primer avance para el posible desarrollo de nuevas metodologías en la aplicación de PDT en células no adherentes usando recubrimientos de TiO2-m.