Logic gates consisting of DNA molecules are useful for direct processing of information that relates to biomolecules
including DNA at nanoscale. This study is aimed at demonstrating operation of the DNA logic gates by optical
manipulation of micro-droplets that contain DNA to show potential of photonics techniques in realizing nanoscale
computing. Connections of different DNA logic gates are reconfigurable owing to flexibility in manipulating the
micro-droplets. The method is effective in, for example, implementing logic operations in limited-volumes at
multiple positions in parallel, enhancing an operation rate, and decreasing sample consumption, and it can be a
promising technique applicable to photonic DNA computing.
We used a two-input and one-output AND or OR gate consisting of DNA in experiments. The individual
inputs, A and B, were encoded into different DNA molecules, I1 and I2, and the output was obtained from a
fluorescence signal. Input A (B) is 1 when DNA I1 (I2) exists, and 0 when the DNA does not exist. Microdroplets were made by mixing DNA solution, acetophenone as solvent, and sorbitan monooleate as surfactant. For
AND/OR operation, two micro-droplets, one of which contained input-DNAs and the other contained AND/OR
logic gates, were optically manipulated to be in contact each other; then the micro-droplets coalesced and the
operation started. Experimental results show that expected fluorescence intensities are obtained as the output
for all possible input values, and logic operation can be implemented successfully in optically manipulated microdroplets.