Abstract
We fabricated a miniaturized electrochemical uric acid biosensor with a 3-aminopropyltriethoxysilane (APTES)-modified indium tin oxide (ITO) microelectrode array (μEA). The ITO-μEA on a glass plate was immobilized with the enzyme uricase, through a cross-linker, bis[sulfosuccinimidyl]suberate (BS3). The enzyme-immobilized electrode (uricase/BS3/APTES/ITO-μEA/glass) was characterized by atomic force microscopy and electrochemical techniques. The cyclic voltammetry and impedance studies show an effective binding of uricase at the μEA surface. The amperometric response of the modified electrode was measured towards uric acid concentration in aqueous solution (pH 7.4), under microfluidic channel made of polydimethylsiloxane. The μEA biosensor shows a linear response over a concentration range of 0.058 to 0.71 mM with a sensitivity of 46.26 μA mM−1 cm−2. A response time of 40 s reaching a 95% steady-state current value was obtained. The biosensor retains about 85% of enzyme activity for about 6 weeks. The biosensor using μEA instead of a large single band of electrode allows the entire core of the channel to be probed though keeping an improved sensitivity with a small volume of sample and reagents.Electronic supplementary materialThe online version of this article (doi:10.1186/2194-0517-2-5) contains supplementary material, which is available to authorized users.
Highlights
The synthesis of a suitable polymeric system in vascular applications is one of the vital issues that material engineers can help physicians and surgeons (Grundfest-Broniatowski 2013)
Considering the characteristics required for medical applications, the series of polyurethanes based on polydimethyl siloxane (PDMS) (80%) and polytetramethylene ether glycol (PTMG) (20%) were synthesized by solution polymerization using a mixture of THF and toluene solvents, and BD and polyhedral oligomeric silsquioxane (POSS) as chain extenders
Polyurethane formation was confirmed by attenuated total reflection (ATR)-Fourier transform infrared spectroscopy (FTIR) spectroscopy
Summary
The synthesis of a suitable polymeric system in vascular applications is one of the vital issues that material engineers can help physicians and surgeons (Grundfest-Broniatowski 2013). Polyurethanes (PUs) were considered in this research work mainly because polymers can be tailor made to match the properties of vascular prosthesis This means that PUs can provide different physical, mechanical and biological properties by aptly selection of the soft and the hard segment components, according to vascular implant requirements. In the synthesis of PUs, the POSS nano-particles were entered into the chain structure along with butanediol, as a co-chain extender, to investigate the effect of nano-particles on the synthesized PUs’ mechanical and biological properties. The hydrophilicity of the surface of the synthesized polyurethanes was investigated by measuring the contact angle of water droplet on the film surface For this purpose, water droplets were placed on a sample surface using a microsyringe and photographed. Differential scanning calorimetry (DSC) was performed under nitrogen atmosphere on a Netzsch DSC 200 F (Netzsch, Bavaria, Germany) fitted with an air cooling compressor at a constant rate of 10 °C/min reciprocating from −130 to 250 °C and 250 to −130 °C and from −130 to 300 °C to eliminate thermal history
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