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《Acta Academiae Medicine Militaris Tertiae》 2002-01
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Effects of target DNA chain length on hybridization efficiency with piezoelectric gene sensor

LIU Ming hua, FU Wei ling, XUE Qiang, HUANG Qing, WANG Song lin (Department of Clinical Laboratories, Southwest Hospital, Third Military Medical University, Chongqing 400038, China)  
Objective To investigate the effects of the length of target DNA chain on hybridization efficiency in piezoelectric gene sensor arrays. Methods A gene sensor array of 2×5 was made with gene probes of 20 bases immobilized on gold coated surfaces, then 7 kinds of target DNA in different lengths were hybridized on it respectively. The changes of oscillation frequency of the crystal were collected and analyzed with aid of computer. The hybridization time, frequency alteration and kinetic parameters caused by the hybridization of DNA chains in various lengths were compared. Result Following the increase of target chain length, the hybridization time had a tendency of prolonging. For target DNA of 20 to 108 bases, the frequency difference (△F) showed a linear relation to the base number, but for target DNA of 225, 379 or 654 bases, the frequency was reduced and showed no obvious relationship, which was due to the elevation of dissociation constants. Conclusion In the piezoelectric gene sensor, the oscillation frequency of the crystal is increased following the increase of target chain length. Reduced frequency reaction for DNA sequence of longer target chain might be owing to lower rigidity on the crystal surface, easier formation of complicated steric construction and the intention of self renaturation.