2010
Autores
Pinto, AMR; Frazao, O; Santos, JL; Lopez Amo, M; Kobelke, J; Schuster, K;
Publicação
JOURNAL OF LIGHTWAVE TECHNOLOGY
Abstract
sThe interrogation of a Fabry-Perot cavity through a dual wavelength Raman fiber laser is reported. The proposed sensing system is based on the use of a dual wavelength Raman fiber laser to generate two quadrature phase-shifted signals that allow the recovery of the temperature change sensed by the Fabry-Perot interferometric cavity. The dual wavelength Raman fiber laser is based on fiber Bragg gratings combined with a distributed mirror. The Fabry-Perot cavity is fabricated by splicing a short length of a suspended-core microstructured fiber to a single mode fiber. The use of this sensing system allows a passive and accurate interrogation of the temperature, while taking advantage of the Rayleigh scattering growth as a distributed mirror in the laser.
2010
Autores
Santos, JL; Pandita, D; Rodrigues, J; Pego, AP; Granja, PL; Balian, G; Tomas, H;
Publicação
MOLECULAR PHARMACEUTICS
Abstract
As mesenchymal stem cells (MSCs) can differentiate into multiple cell types, the delivery of exogenous genes to this type of cell can be an important tool in tissue regeneration and engineering. However transfection of MSCs using nonviral gene delivery vectors is difficult, the development of more efficient and safe DNA vehicles being necessary. Moreover, specific transfection of MSCs may be required to avoid unwanted side effects in other tissues. In this study, a novel family of gene delivery vectors based on poly(amidoamine) (PAMAM) dendrimers functionalized with peptides displaying high affinity toward MSCs was prepared. The vectors were characterized with respect to their ability to neutralize, bind and compact plasmid DNA (pDNA). The complexes formed between the vectors and pDNA were analyzed concerning their size, zeta-potential, capacity of being internalized by cells and transfection efficiency. These new vectors exhibited low cytotoxicity, receptor-mediated gene delivery into MSCs and transfection efficiencies superior to those presented by native dendrimers and by partially degraded dendrimers.
2010
Autores
Santos, JL; Oliveira, H; Pandita, D; Rodrigues, J; Pego, AP; Granja, PL; Tomas, H;
Publicação
JOURNAL OF CONTROLLED RELEASE
Abstract
A new family of gene delivery vectors is synthesized consisting of a medium-size generation PAMAM dendrimer (generation 5, with amine termini) core randomly linked at the periphery to hydrophobic chains that vary in length (12 to 16 carbon alkyl chains) and number (from 4.2 to 9.7 in average). The idea subjacent to the present work is to join the advantages of the cationic nature of the dendrimer with the capacity of lipids to interact with biological membranes. Unlike other amphiphilic systems designed for the same purpose, where the hydrophobic and hydrophilic moieties coexist in opposite sides, the present vectors have a hydrophilic interior and a hydrophobic corona. The vectors are characterized in respect to their ability to neutralize, bind and compact plasmid DNA (pDNA). The complexes formed between the vectors and pDNA are analyzed concerning their size, zeta-potential, resistance to serum nucleases, capacity of being internalized by cells and transfection efficiency. These new vectors show a remarkable capacity for mediating the internalization of pDNA with minimum cytotoxicity, being this effect positively correlated with the -CH(2)-content present in the hydrophobic corona. Gene expression in MSCs, a cell type with relevancy in the regenerative medicine clinical context, is also enhanced using the new vectors but, in this case, the higher efficiency is shown by the vectors containing the smallest hydrophobic chains.
2010
Autores
Pinto, AMR; Frazao, O; Santos, JL; Lopez Amo, M;
Publicação
APPLIED PHYSICS B-LASERS AND OPTICS
Abstract
In this work, a multiwavelength fiber Raman laser based on a highly birefringent photonic crystal fiber loop mirror is presented. A laser resonator is formed when the Raman amplification with cooperative Rayleigh scattering in a dispersion-compensating fiber is used as a distributed mirror and combined with a photonic crystal fiber loop mirror filtering structure. Stable multiwavelength lasing at room temperature is achieved due to the low temperature sensitivity of the highly birefringent photonic crystal fiber.
2010
Autores
Aref, SH; Zibaii, MI; Kheiri, M; Porbeyram, H; Latifi, H; Frazao, O; Araujo, FM; Ferreira, LA; Santos, JL; Kobelke, J; Schuster, K;
Publicação
FOURTH EUROPEAN WORKSHOP ON OPTICAL FIBRE SENSORS
Abstract
In this work, two all-fibre interferometric configurations based on suspended core fibres (SCF) are investigated. A Fabry-Perot cavity made of SCF spliced in-between segments of single-mode and hollow-core fiber is proposed. An alternative sensing head configuration formed by the insertion of a length of SCF as a birefringence element in a Sagnac interferometer is also demonstrated. The sensitivity to pressure and temperature was determined for both configurations.
2010
Autores
Frazao, O; Amaral, LMN; Santos, JL; Roy, P; Jamier, R; Fevrier, S;
Publicação
2ND WORKSHOP ON SPECIALTY OPTICAL FIBERS AND THEIR APPLICATIONS WSOF-2
Abstract
In this work it is investigated the strain and temperature sensing characteristics of modal interferometers supported by two Bragg fibers with different cross-section cladding geometries. It is shown that the sensitivity to these measurands is different for the two fibers, which turns feasible the conception of several sensing configurations based on the combination of these two fiber types for simultaneous measurement of strain and temperature.
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