A novel microassay for measuring blood alcohol concentration using a disposable biosensor strip

A novel disposable amperometric biosensor strip for determination of blood alcohol concentration (BAC) with small volume of sample has been constructed using screen-printed electrodes (SPE), nanocomposite film and alcohol dehydrogenase (ADH). Firstly, the GNPs–MWCNT–Nafion nanocomposite film modified on a working electrode was made of Nafion-117, multi-wall carbon nanotubes (MWCNT) and gold nanoparticles (GNPs). After that Meldola's blue (MB) acted as an electron transfer mediator and the mixed solution of ADH, nicotinamide adenine dinucleotide (NAD+) were modified in order on the nanocomposite film. At last, a hydrophilic membrane which had an eyehole in center was placed at the outermost of the working area to make a reaction tank of 5 μL, then the hydrophilic membrane/ADH–NAD+/GNPs–MWCNT–MB–Nafion/SPE was prepared. The detection of BAC can be accomplished with 5 μL of blood sample obtained precisely by siphonage. Optimum conditions of the biosensor were experimentally determined by varying several important parameters: working potential, solution pH value, environmental temperature and interferences. Experimental results indicated that the biosensor possessed a good accuracy and stability, the linear response range was 2.0 × 10−4 to 25 × 10−3 mol/L and the detection limit of the biosensor was 5.0 × 10−5 mol/L (S/N = 3). In the measurement of blood samples, the proposed biosensor had excellent detection performance for measuring BAC and showed a good correlation with gas chromatography. The prepared biosensor strip can be valid for the analysis of BAC.