RESUMO
The autofluorescence of fingermarks is used for their detection. The components responsible for this autofluorescence are largely unknown. Thin layer chromatography and fluorescence spectroscopy were used to identify autofluorescent components and evaluate their forensic value. Based on our results, tryptophan is hypothesized to be a major contributor to the autofluorescence when part of peptides or proteins, id est, not in its free form. Part of the autofluorescence could be assigned to a kynurenine derivative. Pheophorbide A, a metabolite of chlorophyll, is inferred as a red fluorescent fingermark component. Chlorophyll is a plant pigment which implies that dietary information can potentially be retrieved from fingermarks.
Assuntos
Dermatoglifia , Fluorescência , Bilirrubina/química , Clorofila/análogos & derivados , Clorofila/química , Cromatografia em Camada Fina , Flavina-Adenina Dinucleotídeo/química , Humanos , Cinurenina/química , Luz , Fenilalanina/química , Feofitinas/química , Protoporfirinas/química , Riboflavina/química , Sebo/química , Espectrometria de Fluorescência , Suor/química , Tiamina/química , Triptofano/química , Tirosina/química , Raios Ultravioleta , Vitamina B 6/química , Xanturenatos/química , beta Caroteno/químicaRESUMO
The growing resistance against antifungal agents has renewed the search for alternative treatment modalities, and antimicrobial photodynamic inactivation (PDI) is a potential candidate. The cationic porphyrin 5-phenyl-10,15,20-Tris(N-methyl-4-pyridyl)porphyrin chloride (TriP[4]) is a photosensitizer that in combination with light can inactivate bacteria, fungi, and viruses. For future improvement of the efficacy of PDI of clinically relevant fungi such as Candida albicans, we sought to understand the working mechanism by following the response of C. albicans exposed to PDI using fluorescence confocal microscopy and freeze-fracture electron microscopy. The following events were observed under dark conditions: TriP[4] binds to the cell envelope of C. albicans, and none or very little TriP[4] enters the cell. Upon illumination the cell membrane is damaged and eventually becomes permeable for TriP[4]. After lethal membrane damage, a massive influx of TriP[4] into the cell occurs. Only the vacuole membrane is resistant to PDI-induced damage once TriP[4] passes the plasma membrane. Increasing the incubation time of C. albicans with TriP[4] prior to illumination did not increase the influx of TriP[4] into the cell or the efficacy of PDI. After the replacement of 100% phosphate-buffered saline (PBS) by 10% PBS as the medium, C. albicans became permeable for TriP[4] during dark incubation and the efficacy of PDI increased dramatically. In conclusion, C. albicans can be successfully inactivated by the cationic porphyrin TriP[4], and the cytoplasmic membrane is the target organelle. TriP[4] influx occurred only after cell death.
