PSO+:基于粒子群结合其他迭代算法非线性拟合热对流聚合酶连锁反应的荧光数据

PSO+: nonlinear fitting fluorescence data based on particle swarm optimizing combine with other iteration algorithm

热对流聚合酶连锁反应(CCPCR)利用热对流的原理,让试剂在试管内流动,通过试管上下部分的温度差来达到扩增目的。为了实时检测扩增效果,我们在试剂体系中加入了荧光基团,通过荧光的强弱实时反映扩增的情况。实验结果显示荧光变化曲线符合扩增曲线的S型趋势,但是由于热对流的不稳定性而存在一定的抖动情况,不利于扩增循环阈值(CT值)的计算。为了解决这个问题,本文采用动力学方法,利用双S型函数模型来拟合曲线,使荧光曲线平滑,从而能更好地根据曲线来推断核酸初始浓度,达到定量的目的。同时采用PSO+算法求解双S型函数参数,即用粒子群优化(PSO)算法结合Levenberg-Marquardt、Newton-CG等算法进行曲线拟合,有效克服PSO随机性太强和传统算法Levenberg-Marquardt、Newton-CG等容易陷入局部最优解的缺点,数据拟合结果的R2能够达到0.999 8。此研究对以后的实时荧光热对流扩增的定量检测研究有指导性意义。

The convective polymerase chain reaction(CCPCR)uses the principle of thermal convection to allow the reagent to flow in the test tube and achieve the purpose of amplification by the temperature difference between the upper and lower portions of the test tube.In order to detect the amplification effect in real time,we added a fluorophore to the reagent system to reflect the amplification in real time through the intensity of fluorescence.The experimental results show that the fluorescence curve conforms to the S-type trend of the amplification curve,but there is a certain jitter condition due to the instability of the thermal convection,which is not conducive to the calculation of the cycle threshold(CT value).In order to solve this problem,this paper uses the dynamic method,using the double S-type function model to fit the curve,so that the fluorescence curve is smooth and the initial concentration of the nucleic acid can be deduced better to achieve the quantitative purpose based on the curve.At the same time,the PSO+algorithm is used to solve the double s-type function parameters,that is,particle swarm optimization(PSO)algorithm combined with Levenberg-Marquardt,Newton-CG and other algorithms for curve fitting.The proposed method effectively overcoms PSO randomness and the shortcoming of traditional algorithms such as Levenberg-Marquardt and Newton-CG which are easy to fall into the local optimal solution.The R2 of the data fitting result can reach 0.999 8.This study is of guiding significance for the future quantitative detection of real-time fluorescent heat convection amplification.