We designed and fabricated a smart and stimuli responsive membrane to cater on demand molecular transporting applications. A novel photoswitchable peptide (PSP) was synthesized and attached inside nanoporous anodic alumina membranes (NAAMs) pores. The PSP specifically switched between its cis and trans photostationary states on exposure to 364 nm and 440 nm wavelength lights respectively, which not only provided the ability to control its pore diameter but also the surface chemistry. The switchable molecular transport properties of the PSP-NAAMs have been shown as a function of the light exposure. Most importantly, the molecular transport across PSP-NAAMs could be repeatedly switched between on and off state, which is highly significant for on-demand triggered drug release systems.
The concept of a microfluidic biosensing device based on reflective interferometric spectroscopy (RIfS) is presented in
this article. The key element of the sensor is a highly ordered nanoporous structure of anodic aluminium oxide (AAO)
integrated into a microfluidic chip combined with an optical fiber spectrophotometer. AAO was prepared by
electrochemical anodization of aluminium using 0.3 M oxalic acid. The structural and geometrical features of the AAO
porous structures were controlled to provide optimal RIfS sensing characteristics and there sensing capabilities were
explored using two different strategies; i) detection based on the response generated by pefusion of analyte ions inside
the pores and ii) detection based on specific adsorption of analyte molecules on surface of AAO pores. The second
strategy is based on chemical modification of the AAO surface to target molecules based on specific surface binding
reactions. In this work two cases are presented, including the binding of small thiol molecules on gold-modified AAO
(Au-AAO) and binding of larger targets such as circulating tumour cells (CTC) on antibody-modified AAO. Our
preliminary results show an excellent capability of our system in the detection of different analytes using both strategies,
and confirm good potential for the development and application of interferometric label-free biosensing devices in a
wide range of biomedical applications.
Tissue engineering and stem cell technologies have led to a rapidly increasing interest in the control of the behavior of mammalian cells growing on tissue culture substrates. Multifunctional polymer coatings can assist research in this area in many ways, for example, by providing low non-specific protein adsorption properties and reactive functional groups at the surface. The latter can be used for immobilization of specific biological factors that influence cell behavior. In this study, glass slides were coated with copolymers of glycidyl methacrylate (GMA) and poly(ethylene glycol) methacrylate (PEGMA). The coatings were prepared by three different methods based on dip and spin coating as well as polymer grafting procedures. Coatings were characterized by X-ray photoelectron spectroscopy, surface sensitive infrared spectroscopy, ellipsometry and contact angle measurements. A fluorescently labelled protein was deposited onto reactive coatings using a contact microarrayer. Printing of a model protein (fluorescein labeled bovine serum albumin) was performed at different protein concentrations, pH, temperature, humidity and using different micropins. The arraying of proteins was studied with a microarray scanner. Arrays printed at a protein concentration above 50 μg/mL prepared in pH 5 phosphate buffer at 10°C and 65% relative humidity gave the most favourable results in terms of the homogeneity of the printed spots and the fluorescence intensity.
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