Biomolecular Computing: From Unconventional Computing to “Smart” Biosensors and Actuators – Editorial Introduction

Abstract

Chemical computing [1] as a subarea of unconventional computing [2] has achieved tremendousdevelopment in the past twodecades, drivenmostly by the idea of making revolutionary changes in computing technology. While the conventional silicon-based electronic technology comes to the physical limit of miniaturization [3], chemical systems might operate at the level of single molecules, bringing information processing systems from the present microsize to novel nanosize [4]. Even more importantly, chemical systems can performmassively parallel computational operations with involvement of as many as 1023 molecules, resulting in a speed of information processing presently impossible in silicon-based computers [5]. Motivated by these ideas from computer science, chemists designed sophisticated switchable molecules and supramolecular complexes to perform logic operations and mimic computing systems [6]. Complex chemical reactions with unusual kinetics (e.g., oscillating diffusional systems – Belousov–Zhabotinsky reactions) [7] were suggested as media performing computing operations [8]. Extensive research in the area of reaction–diffusion computing systems [9] resulted in the formulation of conceptually novel circuits performing information processing with the use of subexcitable chemical media [10]. Novel conceptual approaches required for the usage of new chemical ‘‘hardware’’ were designed, resulting in algorithms potentially capable of solving ‘‘hard-to-solve’’ computational problems, thus demonstrating potential advantages of the novel unconventional chemical computing systems over classic silicon-based systems. The present state of the art of the unconventional chemical computing was summarized in the recent Wiley-VCH book: ‘‘Molecular and Supramolecular Information Processing: From Molecular Switches to Logic Systems,’’ E. Katz – Editor. It should be noted, however, that chemical systems designed for information processing usually suffer from two major problems: (i) They are very difficult to prepare – in other words – the synthetic processes required for their preparation are so complex that only a few laboratories are able to prepare and study the switchable molecules operating as the chemical computing ‘‘hardware.’’ This problem is technical rather than conceptual, and it could be solved at the present level of technology if the molecular computing elements find real applications. (ii) The main challenge in further development of chemical information processing systems is