Metal enhanced fluorescence is a phenomenon that occurs when a fluorophore is positioned near a conductive structure. Structures can be formed by the interaction of high-energy laser with a sample, on which the femtosecond laser pulses interact with the surface without heat effects. This work aims to study nanostructure formation in polished bulk silver, in order to amplify signals of fluorescence. A Titanium-sapphire femtosecond laser was used to mark silver surfaces. SEM images shows nanostructures formed in chaotic agglomerate of nanospheres with size of 50-800nm. Using Protoporphyrin-IX, the fluorescence amplification was around 300 times compared to a surface without the nanostructures.
Alessandra Rossi Paolillo, Fernanda Rossi Paolillo, Alessandro M. Hakme da Silva, Rodrigo Bezerra de Menezes Reiff, Vanderlei Salvador Bagnato, José Marcos Alves
The bone fracture is important public health problems. The lasertherapy is used to accelerate tissue healing. Regarding diagnosis, few methods are validated to follow the evolution of bone microarchitecture. The aim of this study was to evaluate the effects of lasertherapy on bone repair with x-ray microtomography (μCT) and histomorphometry. A transverse rat tibia osteotomy with a Kirchner wire and a 2mm width polymeric spacer beads were used to produce a delayed bone union. Twelve rats were divided into two groups: (i) Control Group: untreated fracture and; (ii) Laser Group: fracture treated with laser. Twelve sessions of treatment (808nm laser, 100mW, 125J/cm2, 50seconds) were performed. The μCT scanner parameters were: 100kV, 100μA, Al+Cu filter and 9.92μm resolution. A volume of interest (VOI) was chosen with 300 sections above and below the central region of the fracture, totaling 601sections with a 5.96mm. The softwares CT-Analyzer, NRecon and Mimics were used for 2D and 3D analysis. A histomorphometry analysis was also performed. The connectivity (Conn) showed significant increase for Laser Group than Control Group (32371±20689 vs 17216±9467, p<0.05). There was no significant difference for bone volume (59±19mm3 vs 47± 8mm3) and histomorfometric data [Laser and Control Groups showed greater amount of cartilaginous (0.19±0.05% vs 0.11±0.09%) and fibrotic (0.21±0.12% vs 0.09±0.11%) tissues]. The negative effect was presence of the cartilaginous and fibrotic tissues which may be related to the Kirchner wire and the non-absorption of the polymeric that may have influenced negatively the light distribution through the bone. However, the positive effect was greater bone connectivity, indicating improvement in bone microarchitecture.
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