Enzymatic and Redox Protein Biosensors

Direct electron transfer has also been achieved with many metalloproteins such as cytochrome C, horseradish peroxidase, microperoxidase (MP-11), myoglobin, hemoglobin, catalase, azurin, and so on, immobilized on different CNT-modified electrodes [45, 61, 144—153]. 

Accumulation, 1 min at 0.2 V. Scan rate, 50mV/s. Measurements performed in 0.5 M acetate buffer (pH 5.9). Reprinted with permission from Ref. [158]. Copyright, 2003, The Royal Society of Chemistry. 

CNTs can also be used as hybridization indicators with amplifying properties as demonstrated by Wang and coworkers [164—166]. They showed that CNTs can play a dual amplification role in both the recognition and transduction events, namely as 

CNTs also have promising applications in the immunosensing field and many examples of such sensor devices can be found in the literature. For example, immunosensors with an electrochemiluminescence readout signal have been designed using CNTs as support of the immunorecognition systems [167]. 

Recently, some papers have started to highlight the performance of PSf-(bio) composites-CNT as electrode material for electrochemical immunosensing [112]. The authors have highlighted the attractive combination of PSf/CNTplus disposable screen-printed electrodes for monitoring the enzymatic activity of horseradish peroxidase and the RIgG inmunosensor response. In both cases an enhanced electroanalytical response was demonstrated in comparison with standard graph-ite/PSf composites. 

The use of aligned CNTs seems to be quite advantageous since the more electro-active ends of the nanotubes are readily accessible to species in solution. Moreover, 

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