Direct quantification of biomolecular interaction by single-molecule force spectroscopy has evolved into a powerful tool for materials and life sciences. We introduce an approach in which the unbinding forces required to break intermolecular bonds are measured in a differential format by comparison with a known reference bond (here, a short DNA duplex). In addition to a marked increase in sensitivity and force resolution, which enabled us to resolve single-base pair mismatches, this concept allows for highly specific parallel assays. This option was exploited to overcome cross-reactions of antibodies in a protein biochip application.

DOI: 10.1126/science.1084713
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