Abstract:
:Atomic force microscopy (AFM) can be used to probe the mechanics of molecular recognition between surfaces. In the application known as "chemical force" microscopy (CFM), a chemically modified AFM tip probes a surface through chemical recognition. When modified with a biological ligand or receptor, the AFM tip can discriminate between its biological binding partner and other molecules on a heterogeneous substrate. The strength of the interaction between the modified tip and the substrate is governed by the molecular affinity. We have used CFM to probe the interactions between short segments of single-strand DNA (oligonucleotides). First, a latex microparticle was modified with the sequence 3'-CAGTTCTACGATGGCAAGTC and epoxied to a standard AFM cantilever. This DNA-modified probe was then used to scan substrates containing the complementary sequence 5'-GTCAAGATGCTACCGTTCAG. These substrates consisted of micron-scale, patterned arrays of one or more distinct oligonucleotides. A strong friction interaction was measured between the modified tip and both elements of surface-bound DNA. Complementary oligonucleotides exhibited a stronger friction than the noncomplementary sequences within the patterned array. The friction force correlated with the measured strength of adhesion (rupture force) for the tip- and array-bound oligonucleotides. This result is consistent with the formation of a greater number of hydrogen bonds for the complementary sequence, suggesting that the friction arises from a sequence-specific interaction (hybridization) of the tip and surface DNA.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Mazzola LT,Frank CW,Fodor SP,Mosher C,Lartius R,Henderson Edoi
10.1016/S0006-3495(99)77447-3subject
Has Abstractpub_date
1999-06-01 00:00:00pages
2922-33issue
6eissn
0006-3495issn
1542-0086pii
S0006-3495(99)77447-3journal_volume
76pub_type
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