More powerful biomolecular computers
  Biomolecular computers, along with quantum computers, may be a future alternative for traditional, silicon-based computers. Main advantages of biomolecular computers are massive parallel processing of data, expanded capacity of storing information and compatibility with living organisms (first attempts of using biomolecular computers in cancer therapy through blocking of improper genetic information are described in Benenson et al.(2004). However, biomolecular computers have several drawbacks including time-consuming procedures of preparing of input, problems in detecting output signals and interference with by-products. Due to these obstacles, there are few laboratory implementations of theoretically designed DNA computers (like the Turing machine and pushdown automaton), but there are many implementations of DNA computers for particular problems. The first practical laboratory implementation of the general theoretical model of a machine performing DNA-based calculations was a simple two-symbol two-state finite automaton established by Benenson et al.(2001). In the present work, we propose a new attitude, extending the capability of DNA-based finite automaton, by employing two or potentially more restriction enzymes instead of one used in other works. This creates an opportunity to implement in laboratories of more complex finite automata and other theoretical models of computers: pushdown automata, Turing machines. 
Janusz Blasiak, Tadeusz Krasinski, Tomasz Poplawski, Sebastian   Sakowski
cs.ET cs.FL physics.bio-ph