高灵敏度的精确DNA链置换逻辑门研究

Research on high-sensitive precise logic gates based on DNA strand replacement

随着生物化学技术的不断发展,以DNA分子作为存储数据和运算媒介的新型计算模型引起了研究者的广泛关注.采用编码DNA序列构建分子逻辑门是实现DNA可编程计算的基础,虽然传统的跷跷板门(seesaw gate)作为一种DNA逻辑门能够实现阶跃函数的效果,但是它在阈值附近的变化相对平缓,而且当输入超过阈值后,输出随输入增加难以稳定于期望数值,为此文章提出了基于DNA链置换的阶跃函数门.该逻辑门以四域信号链作为统一的DNA编码形式,通过湮灭反应设定阈值信号,通过支点互补程度控制反应顺序,使逻辑门的输出信号不但在阈值附近具有较高的突变灵敏度和准确度,而且当输入超过阈值后能稳定于期望值.随后基于阶跃函数门提出了能够区分"无信号输入信号"和"输入信号为低位"的与、或、非和异或门,解决了非门难以直接表示、需要通过双轨逻辑间接表示的问题.

With the development of biochemical technology,new computing models that use DNA molecules as storage data and computing media have attracted widespread attention from researchers.One of the basic tasks of programmable DNA computing is to build logic gates with coded DNA.Previous works have implemented a seesaw gate to achieve step function,however this approach changes relatively gentle near threshold and its output is difficult to stabilize on expected value when input increases.In this article,a step function gate based on DNA strand displacement was proposed,of which the output signal has high mutation sensitivity and accuracy near threshold,and ability to maintain stability on expected value.Its threshold is set by annihilation,its reaction order is controlled by degree of toehold complementarity and it uses"four-domain"encoding as universal DNA signal strand form.Then based on step function gate,the AND,OR,NOT and XOR gate capable of distinguishing between"no input signal"and"input signal is low"were proposed,which solves the problem that NOT gates are difficult to implement using direct representations and usually indirectly represented by dual-rail logic.