The Luminescence of 1,8-Diazafluoren-9-One/Titanium Dioxide Composite Thin Films for Optical Application

Abstract

<jats:p>The investigation of innovative label-free α-amino acids detection methods represents a crucial step for the early diagnosis of several diseases. While 1,8-diazafluoren-9-one (DFO) is known in forensic application because of the fluorescent products by reacting with the amino acids present in the papillary exudate, its application for diagnostic purposes has not been fully investigated. The stabilization of DFO over a transparent substrate allows its complexation with biomolecules for the detection of α-amino acids. In this study, DFO was immobilized into a titanium dioxide (TiO2) matrix for the fluorescence detection of glycine, as a target α-amino acid (a potential marker of the urogenital tract cancers). The DFO/TiO2 composite was characterized by atomic force microscopy, spectroscopic ellipsometry, fluorescence spectroscopy and fluorescence microscopy. The performed fluorescent studies indicate spectacular formation of aggregates at higher concentration. The measurements performed using various fluorescence and microscopic techniques together with the suitable analysis show that the aggregates are able to emit short-lived fluorescence.</jats:p>

Nonconventional 1,8-Diazafluoren-9-One Aggregates for Green Light Enhancement in Hybrid Biocompatible Media

“…In addition, using the quantum chemical calculations, we confirmed the energetic tendency of the DFO molecule to aggregate with a preference for the dimer structure formation. This result is strongly compatible with our recent publication results [ 21 , 22 , 23 ], where we confirmed the aggregation ability of DFO in ethanol and the emission of DFO aggregates in ethanol with an emission maximum at a similar wavelength as the DFO complex with glycine (an alpha-amino acid). These results significantly affect the application of DFO in Friction Ridge Analysis and are predictive of the application of DFO on different types of substrates with different surface energy characteristics.…”

“…In addition, it is worth noting that aggregation processes are often overlooked in the interpretation of spectroscopic properties, as evidenced by current procedures for the visualization of dactyloscopic traces with DFO. DFO working solutions contain high concentrations of DFO, and in the process of visualization of dactyloscopic traces, not only DFO complexes with amino acids but also DFO aggregates are involved, as indicated by our previous work [ 21 , 22 , 23 ].…”

“…An increase in the disorder of DFO/TiO2/CNW complexes and film thicknesses of the layers were evidenced by the large variation in the values of the obtained refractive indices. The derived ellipsometric results were compared with recently studied dyes in the TiO2 matrix [21]. In the case of TiO2, the surface structure is disordered, which will be Ellipsometry is an established optical technique for measuring thin films and bulk materials.…”

“…Ellipsometrically estimated properties of DFO/TiO 2[21] films related to DFO/TiO 2 /CNW films with different concentrations of DFO dye.…”

Spectroscopic evidence of fluorescence by 1,8‐diazafluoren‐9‐one aggregates—A prospective new ultrasensitive method for fingerprint trace detection

“…In the previous work, the difference of dipole moments in the ground and excited states was calculated for the free DFO molecule and the hydrogen‐bonded complex (DFO + polar protic solvent). It has been confirmed that also specific solvent effects occur resulting from the interaction of the fluorophore with protic solvents (DFO dissolved in protic solvents, both nonspecific and specific [hydrogen bonding] interactions) [5,15].…”