Biology

Sequence-Selective Detection of Double-Stranded DNA Sequences Using Pyrrole–Imidazole Polyamide Microarrays

Abstract

We describe a microarray format that can detect double-stranded DNA sequences with a high degree of sequence selectivity. Cyclooctyne-derivatized pyrrole–imidazole polyamides were immobilized on azide-modified glass substrates using microcontact printing and a strain-promoted azide–alkyne cycloaddition (SPAAC) reaction. These polyamide-immobilized substrates selectively detected a seven-base-pair binding site incorporated within a double-stranded oligodeoxyribonucleotide sequence even in the presence of an excess of a sequence with a single-base-pair mismatch.

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Sequence-Selective Detection of Double-Stranded DNA Sequences Using Pyrrole–Imidazole Polyamide Microarrays

Elucidation of the Role of Carbon Nanotube Patterns on the Development of Cultured Neuronal Cells

Abstract

Carbon nanotubes (CNTs) promise various novel neural biomedical applications for interfacing neurons with electronic devices or to design appropriate biomaterials for tissue regeneration. In this study, we use a new methodology to pattern SiO2 cell culture surfaces with double-walled carbon nanotubes (DWNTs). In contrast to homogeneous surfaces, patterned surfaces allow us to investigate new phenomena about the interactions between neural cells and CNTs. Our results demonstrate that thin layers of DWNTs can serve as effective substrates for neural cell culture. Growing neurons sense the physical and chemical properties of the local substrate in a contact-dependent manner and retrieve essential guidance cues. Cells exhibit comparable adhesion and differentiation scores on homogeneous CNT layers and on a homogeneous control SiO2 surface. Conversely, on patterned surfaces, it is found that cells preferentially grow on CNT patterns and that neurites are guided by micrometric CNT patterns. To further elucidate this observation, we investigate the interactions between CNTs and proteins that are contained in the cell culture medium by using quartz crystal microbalance measurements. Finally, we show that protein adsorption is enhanced on CNT features and that this effect is thickness dependent. CNTs seem to act as a sponge for culture medium elements, possibly explaining the selectivity in cell growth localization and differentiation.

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Elucidation of the Role of Carbon Nanotube Patterns on the Development of Cultured Neuronal Cells

Application of nanotechnology to control bacterial adhesion and patterning on material surfaces

Abstract

Bacterial adhesion and biofilm formation on surfaces raises health hazard issues in the medical environment. Previous studies of bacteria adhesion have focused on observations in their natural/native environments. Recently, surface science has contributed in advancing the understanding of bacterial adhesion by providing ideal platforms that attempt to mimic the bacteria's natural environments, whilst also enabling concurrent control, selectivity and spatial control of bacterial adhesion. In this review, we will look at techniques of how nanotechnology is used to control cell adhesion on a planar scale, in addition to describing the use of nanotools for cell micropatterning. Additionally, it will provide a general background of common methods for nanoscale modification enabling biologist unfamiliar with nanotechnology to enter the field.

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Application of nanotechnology to control bacterial adhesion and patterning on material surfaces

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