Intelligent DNA chips: logical operation of gene expression profiles on DNA computers.

We propose a new type of DNA chips with logical operations executable. In DNA computing researches, some methods have been developed to represent and evaluate Boolean functions on DNA strands. By employing the evaluation methods, we are able to deal with logical operations such as logical-and and logical-or for gene expressions. By combining with the DNA Coded Number method, we implement universal DNA chips which not only detect gene expressions but also find logical formulae of gene expressions. An important advantage of our intelligent DNA chip is that the intensity of the fluorescence at each element is not only proportional to the expression level of the genes in the sample but also proportional to the satisfiability level of the Boolean formula at the element with the gene expression pattern. These features of the intelligent DNA chip and the DCN method allow us more quantitative analyses of gene expression profiles and the logical operations.