RESUMEN
The development of nerve conduits with a three-dimensional porous structure has attracted great attention as they closely mimic the major features of the natural extracellular matrix of the nerve tissue. As low levels of reactive oxygen species (ROS) function as signaling molecules to promote cell proliferation and growth, this study aimed to fabricate protoporphyrin IX (PpIX)-immobilized cellulose (CEPP) monoliths as a means to both guide and stimulate nerve regeneration. CEPP monoliths can be fabricated via a simple thermally induced phase separation method and surface modification. The improved nerve tissue regeneration of CEPP monoliths was achieved by the activation of mitogen-activated protein kinases, such as extracellular signal-regulated kinases (ERKs). The resulting CEPP monoliths exhibited interconnected microporous structures and uniform morphology. The results of in vitro bioactivity assays demonstrated that the CEPP monoliths with under 0.54 ± 0.07 µmol/g PpIX exhibited enhanced photodynamic activity on Schwann cells via the generation of low levels of ROS. This photodynamic activation of the CEPP monoliths is a cell-safe process to stimulate cell proliferation without cytotoxic side effects. In addition, the protein expression of phospho-ERK increased considerably after the laser irradiation on the CEPP monoliths with low content of PpIX. Therefore, the CEPP monoliths have a potential application in nerve tissue regeneration as new nerve conduits.
Asunto(s)
Celulosa/química , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Protoporfirinas/farmacología , Células de Schwann/citología , Animales , Línea Celular , Proliferación Celular/efectos de los fármacos , Proliferación Celular/efectos de la radiación , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/efectos de la radiación , Terapia por Luz de Baja Intensidad , Regeneración Nerviosa , Tejido Nervioso/química , Fosforilación , Protoporfirinas/química , Ratas , Especies Reactivas de Oxígeno/metabolismo , Células de Schwann/efectos de los fármacos , Células de Schwann/metabolismo , Células de Schwann/efectos de la radiaciónRESUMEN
For bioabsorbable vascular scaffolds (BVS), thrombosis is an important clinical problem. Poly(lactic acid) (PLA), as a commonly used manufacturing material of BVS, is always facing thrombosis events in the early stage of BVS implantation, because of a lack of anticoagulant properties. Herein, we introduced carboxyl functional groups on the surface of PLA by photooxidation modification and then used NH2-PEG-NH2 as an intermediate to graft chondroitin sulfate (CS) onto PLA. Fourier transform infrared spectroscopy was used to verify the success of each step of the modification, and X-ray photoelectron spectroscopy was used as a further supplement. The methyl of PLA was oxidized to carboxyl by photooxidation, and the hydrophilicity of PLA surface was improved. CS made endothelial cells better adhere to PLA and resisted the adhesion of platelets. The results showed that the surface of PLA grafted with CS embodies the advantages of promoting endothelial cell adhesion and antiplatelet adhesion, providing a broader application prospect for the application of PLA in BVS.
Asunto(s)
Anticoagulantes/farmacología , Materiales Biocompatibles/farmacología , Sulfatos de Condroitina/farmacología , Poliésteres/farmacología , Anticoagulantes/química , Materiales Biocompatibles/química , Adhesión Celular/efectos de los fármacos , Células Cultivadas , Sulfatos de Condroitina/química , Células Endoteliales/efectos de los fármacos , Humanos , Ensayo de Materiales , Estructura Molecular , Tamaño de la Partícula , Adhesividad Plaquetaria/efectos de los fármacos , Poliésteres/química , Propiedades de SuperficieRESUMEN
This study deals with the preparation and properties of a new class of organic-inorganic hybrids from renewable resources. The hybrids were synthesized by an acid-catalyzed curing of epoxidized triglycerides in the presence of an organophilic montmorillonite (a modified clay). The mechanical properties were improved by the incorporation of clay in the oil-based polymer matrix. The reinforcement effect due to the addition of clay was confirmed by dynamic viscoelasticity analysis. The hybrids showed relatively high thermal stability. The co-curing of epoxidized soybean and linseed oils in the presence of clay produced hybrids with controlled mechanical and coating properties. The barrier property of the hybrid towards water vapor was superior to that of the oil polymer. The development of the present hybrids consisting of inexpensive renewable resources, triglyceride and clay is expected to contribute to global sustainability.
Asunto(s)
Bentonita/química , Aceite de Linaza/química , Polímeros/síntesis química , Aceite de Soja/química , Triglicéridos/química , Silicatos de Aluminio/química , Biopolímeros/química , Arcilla , Compuestos Epoxi/química , Polímeros/químicaRESUMEN
Protease-catalyzed polymerization and copolymerization of L-glutamic acid diethyl ester hydrochloride (1) have been performed in a buffer of high concentration. Papain and bromelain showed high catalytic activity toward the polymerization. H-H COSY NMR analysis of the product showed the exclusive formation of poly(alpha-peptide), which was further confirmed by comparison with NMR spectra of poly(alpha-methyl gamma-L-glutamate). The papain-catalyzed polymerization of gamma-methyl L-glutamate did not occur under the similar reaction conditions, supporting the regioselective production of the polymer having an alpha-peptide linkage from 1. The effects of the reaction parameters have been systematically investigated. The copolymerization of 1 with various amino acid esters took place by the papain catalyst to give peptide copolymers.