Enzymatic Control of Metal Deposition as Key Step for a Low-Background Electrical Detection for DNA Chips

Institute for Physical High Technology, P.O. Box 100239, 07702 Jena, Germany.
Nano Letters (Impact Factor: 13.59). 08/2005; 5(7):1475-82. DOI: 10.1021/nl050824k
Source: PubMed


Electrical detection of DNA using nanoparticle labels in combination with metal enhancement represents an interesting alternative to fluorescence readout schemes. This electrical method is hampered by unspecific metal deposition, resulting in a lower sensitivity of the assay. A novel enhancement technique based on an enzymatic process is introduced. This approach enables highly specific metal deposition only at the enzyme label, without the background that is typical in the case of the conventional metal enhancement process of growing nanoparticles. The enzymatic enhancement leads to a significant increase in sensitivity, and the detection of single base mismatches demonstrates the high specificity of the novel enhancement approach.

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    • "In this way, the pattern can be formed very quickly and without the need for expensive ion optics. After exposure to the beam, protein patterns were detected and visualized using three different methods chosen to be representative of common approaches: (1) formation of localized diformazan precipitates by patterned alkaline phosphatase (AP) from its substrate BCIP-NBT [24], [25], [26], (2) binding of gold nanoparticle probes (40 nm and 100 nm gold particles conjugated with antibodies) [27], [28], [29], by patterned antibodies and avidin, and (3) localized redox formation of silver deposits mediated by patterned horseradish peroxidase (HRP) [30], [31], [32], [33]. "
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