Nanocomposite materials were prepared by sequential drop casting of multi-walled carbon nanotube (MWCNT) suspensions and amphiphilic polybutadiene-block-poly(2-(N,Ndimethylamino)ethyl methacrylate) (PB 290 -b-PDMAEMA 240 ) diblock copolymer micelles on screen-printed electrodes (SPEs). This nanocomposite material was found to be very favorable for integration of myoglobin (Mb) and facilitates a direct electron transfer from an electrode to 2 heme proteins. In that respect, PB 290 -b-PDMAEMA 240 was demonstrated to be a well-suited binding agent. In aqueous solutions, the diblock copolymer forms core-corona micelles (shown by cryogenic transmission electron microscopy, cryo-TEM, and nanoparticle tracking analysis, NTA), which at pH 7 in phosphate buffer exhibit good adhesion to carbon materials (shown by atomic force microscopy, AFM, scanning electron microscopy, SEM, and scanning transmission electron microscopy, STEM) and builds up uniform thin films on a hydrophobic graphite-based substrate. As demonstrated by a quartz crystal microbalance with dissipation monitoring (QCM-D), attractive interactions of Mb and PB 290 -b-PDMAEMA 240 take place when both components are subsequently deposited onto a solid substrate. Spectroscopic studies confirmed that the absorption maximum of Mb remains unaltered, suggesting that at least some protein globules retain their tertiary structure. Cyclic voltammetry and square wave voltammetry show a remarkable (ca 180-fold) increase of the reductive current of Mb after its incorporation into the SPE/MWCNTs/PB 290 -b-PDMAEMA 240 matrix. The herein developed analytical approach was used for the detection of cardiac myoglobin as a very early marker of acute myocardial infarction (AMI) both in plasma of healthy donors and patients with AMI.
Using complex physical and chemical methods (voltammetry, chronoamperometry, microscopy), the inhibitive action of benzotriazole (BTAH) on copper pitting corrosion (PC) was investigated in alkaline-sulphate solutions in a range of temperatures (20-60°C). It was found that in the background electrolyte (1×10-2 M NaOH + 1×10-2 M Na 2 SO 4 (pH 12)), the intensity of copper PC increases with a temperature growth, whereas addition of an adsorptive inhibitor, namely BTAH, increases the resistance of copper to PC at all the temperatures studied and that the effect is the stronger, the higher the temperature is. Full suppression of PC occurs at C(BTAH) = 8×10-4 M (20°C) and at C(BTAH) = 5×10-7 M (60°C). An explanation of the observed effects was suggested from the viewpoint of modern theories of pitting initiation, adsorption and complex formation phenomena.
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