研究结果表明短片段的细胞外DNA在癌症早期诊断、疾病治疗监控等领域有重要的应用前景。目前的DNA提取技术已经可以满足长片段基因组DNA的提取要求，但短片段DNA提取还缺乏成熟有效的方法。本项目提出设计制备不同孔结构和表面性质的介孔SiO2复合磁性粒子，以期实现对短片段DNA的高效和片段均衡性提取。系统研究孔径、孔道结构和表面性质对不同片段长度DNA在粒子表面吸附/脱附过程的影响。结合DNA吸附过程中的构像变化，评价熵变和焓变对吸附过程的调控规律。建立不同长度片段DNA在介孔SiO2复合磁性粒子表面的热力学和动力学吸附模式，为细胞外DNA的高效和片段均衡性提取奠定材料和方法学基础。

Cell-free DNA (cfDNA) with short segments has attracted intensive research interests due to its potential applications in cancer screening, prognosis and monitoring of the efficacy of anticancer therapies. To date the extraction techniques for long segment DNA have been well developed, while there is still no approach for efficient and balanced extraction of cell-free DNA. In this project, we proposed the design and preparation of mesoporous silica-magnetic composite particles with adjustable pore structures and surface properties. The effect of the pore structures and surface properties on the adsorption and desorption processes of DNA with different segment lengths will be investigated systematically. The enthalpy and entropy effect on the adsorption/desorption processes of DNA will be evaluated by combined investigation on the conformation changes of DNA. The thermodynamic and kinetic models for the segment length selective adsorption of DNA on the mesoporous silica-magnetic composite particles will be established. The materials and methodologies derived from this project will pave the way for highly efficient and segment balanced extraction of cell-free DNA.