RESUMO
The combination of scaffolds with desirable topographic characteristics and the use of electrical stimulus consist of a strategy to repair and regenerate tissues. An interesting approach to obtain electroactive scaffolds with the aforementioned features comprises on the use of conducting polymers which can be blended with other biocompatible polymers. In this work, poly(l-lactic acid) (PLLA) and poly(ortho-ethoxyaniline) (POEA) were synthesized and PLLA/POEA mats were prepared for the first time by electrospinning technique. Topographic characterization of PLLA/POEA showed a tunable mean diameter of the nanofibers by changing the electrospinning parameters. The presence of POEA into the blend was confirmed by X-ray photoelectron and Fourier-transform infrared spectroscopy analyses. Differential scanning calorimetry curves of PLLA/POEA exhibited shift positions of Tc and absence of the exothermic peak related to the characteristic isomerization process of POEA at high temperatures. The thermal analysis results indicate a favored miscibility between the polymers which is likely resulted from the strong interaction between polymers functionalities. The homogenous distribution of POEA chains throughout the scaffold rendered redox reversibility property for the mats. Biocompatibility results showed non-cytotoxic features for PLLA/POEA, attesting this novel system as a promising candidate for biological applications.
Assuntos
Materiais Biocompatíveis/química , Teste de Materiais , Nanofibras/química , Poliésteres/química , Polietilenoglicóis/química , Linhagem Celular , HumanosRESUMO
In this work it was studied the production of nanostructured thin films containing alternating layers of poly(allylamine hydrochloride) (PAH) and bovine serum albumin protein (BSA). It was studied the adsorption processes of these materials onto solid surfaces, which included adsorption kinetics and film growth studies by using UV-Vis spectroscopy. The film morphology, thickness and roughness were studied by using atomic force microscopy (AFM). The AFM results showed that the film presented a globular-like surface morphology and a thickness within the nanoscale, which could be controlled by the number of deposited layers. The roughness and thickness of the film depend on the number of deposited bilayers, where the film roughness increased for films with a number of bilayers up to five, after which the film roughness remained almost constant. This is an indicative that the adsorption and growth processes might occur under two different mechanisms, first under the influence of the substrate (films containing up to five bilayers of PAH/BSA), and second under the influence of the film previously deposited (films containing more than five bilayers of PAH/BSA), respectively.
Assuntos
Nanoestruturas , Poliaminas , Soroalbumina Bovina , Adsorção , Animais , Bovinos , Microscopia de Força AtômicaRESUMO
Fibrous mats built from biopolymer have been extensively explored for tissue engineering due mainly to their mimic structure to the extracellular matrix. The incorporation of drug in such scaffolds represents a growing interest for control drug delivery system in order to promote the tissue repair. In the present work, we present an experimental investigation of morphological, thermal, mechanical, drug release, antibacterial and cytotoxicity properties of electrospun PVA/Chitosan and PVA/Chitosan/Tetracycline hydrochloride (TCH) mats for wound dressing. Fibrous mats with cross-linked three-dimensional nanofibers were formed from the polymer blends. A uniform incorporation of drug was achieved along the nanofibers with not significant change on the morphological and thermal properties of the mats. Furthermore, the TCH release profile with a burst delivery during the first 2h allows an effective antibacterial activity on the Gram-negative Escherichia coli as well as on the Gram-positive Staphylococci epidermidis and Staphylococcus aureus. In vitro indirect MTT assay also showed that the developed drug-loaded nanofibrous scaffolds have good cytocompatibility, which was confirmed by scratch assay, indicating that the investigated scaffold may be used as antibacterial wound dressing for healing promotion.
Assuntos
Nanofibras , Bandagens , Quitosana , Álcool de Polivinil , Staphylococcus aureus , TetraciclinaRESUMO
The detection of the carcinogenic trihalomethanes (THM) in public water supplysystems using low-cost equipment has become an essential feature, since these compoundsmay be generated as by-products of water-treatment processes. Here we report on a sensorarray that extends the concept of an "electronic tongue" to detect small amounts ofbromoform, bromodichloromethane and dibromochloromethane, with detection limits aslow as 0.02 mg L-1. The sensor array was made up of 10 sensing units, in whichnanostructured films of conducting and natural polymers were deposited onto goldinterdigitated electrodes. The principle of detection was impedance spectroscopy, withmeasurements carried out in the range between 1 Hz to 1 MHz. Using data at 1 kHz, atwhich the electrical response varied considerably by changing the analyte, we demonstratedwith principal component analysis (PCA) that samples with the 3 brominatedtrihalomethanes can be distinguished from each other and for various concentrations.