No abstract

Collagen hydrogel is a popular extracellular matrix (ECM) material in regenerative medicine and has an isotropic structure. In contrast, native ECM has an anisotropic structure. Electrospinning of collagen dissolved in organic solvents is widely used for fabricating anisotropic collagen nanofibres; however, such fibres are water-soluble and require cross-linking before use as scaffolds for cell culture. Herein, electrospinning using a core-shell nozzle was employed to spin an aqueous acidic solution of collagen and encapsulate it within a shell of polyvinylpyrrolidone (PVP). Subsequently, the core collagen was gelled, and the shell PVP was washed away using a basic ethanol solution to yield anisotropic collagen hydrogel nanofibres. Immunostaining and Fourier transform infrared spectroscopy revealed that the obtained fibres were composed of collagen, and surface PVP was removed completely. Circular dichroism measurements confirmed that the fibres exhibited the triple helical structure characteristic of collagen. Human umbilical vein endothelial cells cultured on the collagen hydrogel fibres were oriented along the fibre direction. Hence, this method is suitable for fabricating fibrous anisotropic collagen hydrogels without chemical and thermal cross-linking, and can facilitate the development of safe medical materials with anisotropy similar to that of native ECM.

The cytotoxic effect of isoflavonoids in the development of different forms of cancer has been reported by epidemiological and dietary studies. Consequently, there is a search for an accurate and reliable method for monitoring the interactions of these chemicals with cancerous cells. We have developed and optimized a fully autonomous electrochemical biosensor for studying the role of isoflavonoids on A549 lung adenocarcinoma cell line. This advanced biosensor uses a prototype 96-electrode (DOX-96) well-type device that allows the measurement of cell respiratory activity via the consumption of dissolved oxygen. The system provides a continuous, real-time monitoring of cell activity upon exposure to naturally occurring polyphenols, specifically resveratrol, genistein, and quercetin. The system is equipped with a multipotentiostat, a 96-electrode well for measurements and cell culturing with 3 disposable electrodes fitted into each well. A comparison with classical "cell culture" techniques indicates that the biosensor provides real-time measurement with no added reagents. A detection limit of 1 x 10(4) was recorded versus 200 and 6 x 10(3) cells/well for MTT and fluorescence assays, respectively. This method was optimized with respect to cell stability, reproducibility, applied potential, cell density per well, volume/composition of cell culture medium per well, and incubation. Others include total measuring time, temperature, and sterilization procedure. This study represents a basic research tool that may allow researchers to study the type, level, and specific influence of isoflavonoids on cells.

Electrospun nanofibers, featured a lower glass-transition temperature than the freezing temperature and a loose mesh structure, allows the direct cryopreservation of adherent cells towards the investigation of cell-material composites.