title: Porphyrin dye into biopolymeric chitosan films for localized photodynamic therapy of cancer.
abstract: Porphyrins and some of its derivatives are well known and widely used as photosensitizers (PSs) for Photodynamic Therapy of Cancer (PDT). The present study regards the characterization and evaluation of a synthesized asymmetric porphyrin dye in solution to be used as PS for PDT. This molecule was also incorporated into biopolymeric films composed by chitosan, polyethylene glycol (PEG) and gelatin in order to overtake some of the disadvantages inherent to the PS, but more important, to evaluate the potential of a system composed by the porphyrin/biopolymer to be applied as localized therapeutic agents. FTIR spectroscopy showed a strong interaction between the polymers involved in the preparation of the films under study: film 1: chitosan, film 2: chitosan/PEG and film 3: chitosan/gelatin. Photochemical studies were performed for the dye in solution and into the three different biopolymeric films. Ground state absorption showed the characteristic bands of these kinds of dyes in solution and also incorporated into the films. The films composed by porphyrin/chitosan and porphyrin into chitosan/gelatin, revealed the presence of non-emissive aggregates exhibiting a strong quenching effect in the fluorescence intensity, quantum yields and lifetimes. In this way, the system composed by the porphyrin incorporated into the chitosan/PEG film presents the best fluorescence quantum yield and lifetime. The transient absorption spectra were obtained for all the systems indicating the formation of an excited triplet state of the porphyrins following excitation, which takes special importance in the generation of phototoxic species namely singlet oxygen. Singlet oxygen quantum yields were also determined and the results obtained were very promising for the dye in solution but also for the dye into the different substrates. The release of the dye from the three different films onto a buffer solution was evaluated and we conclude that after a few days the dye was completely released by the substrates in acidic conditions. Confocal microscopy was used for the determination of the intracellular localization of the compound under study onto HeLa cells (human cervical cancer cells line). The evaluation of the PSs anticancer activity assumes special importance for PDT studies. The system should be less toxic in the dark and more active when irradiated, therefore, toxicity in the dark and phototoxicity studies onto HeLa cells were performed.
authors.affiliation: Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: D P
authors.initials: DP
authors.lastname: Ferreira
authors.affiliation: Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: D S
authors.initials: DS
authors.lastname: Conceição
authors.affiliation: Mountain Research Centre (CIMO), ESA, Polytechnic Institute of Bragança, Campus de Santa Apolónia, 1172, 5301-855 Bragança, Portugal.
authors.forename: R C
authors.initials: RC
authors.lastname: Calhelha
authors.affiliation: Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: T
authors.initials: T
authors.lastname: Sousa
authors.affiliation: Romanian Academy, Institute of Physical Chemistry "Ilie Murgulescu", 202 Splaiul Independentei, Bucharest, Romania.
authors.forename: Radu
authors.initials: R
authors.lastname: Socoteanu
authors.affiliation: Mountain Research Centre (CIMO), ESA, Polytechnic Institute of Bragança, Campus de Santa Apolónia, 1172, 5301-855 Bragança, Portugal.
authors.forename: I C F R
authors.initials: ICFR
authors.lastname: Ferreira
authors.affiliation: Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal. Electronic address: luisfilipevf@ist.utl.pt.
authors.forename: L F
authors.initials: LF
authors.lastname: Vieira Ferreira
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D048271:Chitosan / Q000008:administration & dosage / Q000737:chemistry; D004396:Coloring Agents / Q000008:administration & dosage / Q000737:chemistry; D004337:Drug Carriers / Q000008:administration & dosage / Q000737:chemistry; D065546:Drug Liberation; D005453:Fluorescence; D005780:Gelatin / Q000008:administration & dosage / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D008027:Light; D009369:Neoplasms / Q000188:drug therapy; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000008:administration & dosage / Q000737:chemistry; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000737:chemistry; D011166:Porphyrins / Q000008:administration & dosage / Q000737:chemistry
chemical_list: D004396:Coloring Agents; D004337:Drug Carriers; D017319:Photosensitizing Agents; D011166:Porphyrins; D011092:Polyethylene Glycols; D005780:Gelatin; D048271:Chitosan
keywords: Chitosan; Gelatin; HeLa cells; PEG; Photochemistry; Porphyrin