RESUMO
Living organisms have evolved sophisticated cell-mediated biomineralization mechanisms to build structurally ordered, environmentally adaptive composite materials. Despite advances in biomimetic mineralization research, it remains difficult to produce mineralized composites that integrate the structural features and 'living' attributes of their natural counterparts. Here, inspired by natural graded materials, we developed living patterned and gradient composites by coupling light-inducible bacterial biofilm formation with biomimetic hydroxyapatite (HA) mineralization. We showed that both the location and the degree of mineralization could be regulated by tailoring functional biofilm growth with spatial and biomass density control. The cells in the composites remained viable and could sense and respond to environmental signals. Additionally, the composites exhibited a maximum 15-fold increase in Young's modulus after mineralization and could be applied to repair damage in a spatially controlled manner. Beyond insights into the mechanism of formation of natural graded composites, our study provides a viable means of fabricating living composites with dynamic responsiveness and environmental adaptability.
Assuntos
Adesinas Bacterianas/genética , Biofilmes/efeitos da radiação , Durapatita/química , Proteínas de Escherichia coli/genética , Escherichia coli/efeitos da radiação , Proteínas/genética , Adesinas Bacterianas/metabolismo , Adesinas Bacterianas/efeitos da radiação , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/metabolismo , Materiais Biocompatíveis/efeitos da radiação , Biofilmes/crescimento & desenvolvimento , Materiais Biomiméticos/química , Materiais Biomiméticos/metabolismo , Materiais Biomiméticos/efeitos da radiação , Biomineralização/efeitos da radiação , Engenharia Celular/métodos , Relação Dose-Resposta à Radiação , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Proteínas de Escherichia coli/efeitos da radiação , Expressão Gênica , Luz , Mytilus , Proteínas/metabolismo , Proteínas/efeitos da radiação , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Recombinantes de Fusão/efeitos da radiaçãoRESUMO
We demonstrated previously that human glioblastoma cell lines accumulated heat shock protein (hsp)72, not only after heat shock, but also after, gamma-ray or UV irradiation. In the present study, we investigated whether the binding activity of heat shock transcription factor (HSF) to the heat shock element (HSE) of the hsp72 gene promoter increased after UV irradiation of human glioblastoma A-172 cells. A gel mobility-shift assay showed that the activated HSF level increased markedly after UV irradiation. Furthermore, UV irradiation of nuclear extracts in vitro did not activate HSF, whereas in vitro heat shock treatment did. These results suggest that HSF activation can be induced by UV irradiation at normal physiological temperature and hsp72 accumulation results from an increased activated HSF level, i.e. a transcriptional up-regulation of hsp72. In addition, the mechanism responsible for UV-induced HSF activation may differ from the process that operates in heat-treated cells.