Ramakrishnan Anand, Sadana Ajit
Chemical Engineering Department, University of Mississippi, 134 Anderson Hall, University, MS 38677-9740, USA.
Biosystems. 2002 Aug-Sep;66(3):165-77. doi: 10.1016/s0303-2647(02)00052-7.
A fractal analysis of DNA binding and dissociation kinetics on biosensor surfaces is presented. The fractal approach provides an attractive, convenient method to model the kinetic data taking into account the effects of surface heterogeneity brought about by ligand immobilization. The fractal technique can be used in conjunction or as an alternate approach to conventional modeling techniques, such as the Langmuir model, saturation model, etc. Examples analyzed include a DNA molecular beacon biosensor and a plasmid DNA-(cationic polymer) interaction biosensor. The molecular beacon example provides some insights into the nature of the surface and how it influences the binding rate coefficients. The DNA-cationic polymer interaction example provides some quantitative results on the binding and dissociation rate coefficients. Data taken from the literature may be modeled, in the case of binding, using a single-fractal analysis or a dual-fractal analysis. The dual-fractal analysis results indicate a change in the binding mechanism as the reaction progresses on the surface. A single-fractal analysis is adequate to model the dissociation kinetics in the example presented. Relationships are presented for the binding rate coefficients as a function of their corresponding fractal dimension, D(f), which is an indication of the degree of heterogeneity that exists on the surface. When analyte-receptor binding is involved, an increase in the heterogeneity of the surface (increase in D(f)) leads to an increase in the binding rate coefficient.
本文介绍了生物传感器表面DNA结合和解离动力学的分形分析。分形方法提供了一种有吸引力且方便的方法来对动力学数据进行建模，同时考虑到配体固定化所带来的表面异质性影响。分形技术可与传统建模技术（如朗缪尔模型、饱和模型等）结合使用或作为替代方法。分析的示例包括DNA分子信标生物传感器和质粒DNA -（阳离子聚合物）相互作用生物传感器。分子信标示例提供了对表面性质及其如何影响结合速率系数的一些见解。DNA -阳离子聚合物相互作用示例给出了关于结合和解离速率系数的一些定量结果。对于结合情况，从文献中获取的数据可以使用单分形分析或双分形分析进行建模。双分形分析结果表明，随着反应在表面上进行，结合机制发生了变化。在给出的示例中，单分形分析足以对解离动力学进行建模。给出了结合速率系数与其相应分形维数D(f)的函数关系，分形维数D(f)表明了表面存在的异质性程度。当涉及分析物 -受体结合时，表面异质性的增加（D(f)增加）会导致结合速率系数增加。
