Magnetic Composite Microspheres with Controlled Mesoporous Shell for Highly Efficient DNA Extraction and Fragment Screening

Rapid extraction and screening of high purity DNA fragments is an indispensable technology in advanced molecular biology. In this article, mesoporous magnetic composite microspheres (MSP@mTiO2) with tunable pore sizes are successfully fabricated for high purity DNA extraction and fragment screening. Due to the strong complexation ability of Ti4+ with DNA phosphate groups and the high specific surface area of mesoporous microspheres, the MSP@mTiO2 microspheres possess excellent adsorption performance, the saturated loading capacity of MSP@mTiO2 with specific surface area of 122 m2/g is as high as 575 g/mg for salmon sperm specimen. ITC experiment demonstrates that the DNA adsorption on MSP@mTiO2 microspheres is mainly driven by entropy, which gives us more potential ways to regulate the balance of adsorption and desorption. Meanwhile, the mesoporous MSP@mTiO2 microspheres exhibit much higher extraction efficiency compared with non-porous MSP@TiO2 for whole genome DNA from Arabidopsis thaliana plants. Interestingly, the DNA frangements with different lengths can be screened by simply regulating the pore size of MSP@mTiO2 or concentration of Na3PO4 in eluent. Small pore size and low phosphate concentration are advantageous for the extraction of short-stranded DNA fragments, the DNA fragments (≤1000 bp) can be efficiently extracted when the mesopore size of MSP@mTiO2 is lower than 7.6 nm. The extraction results from the mesoporous composite microspheres provide new promising insights on the DNA purification and screening from complex biological samples.