High-efficient separation of deoxyribonucleic acid from pathogenic bacteria by hedgehog-inspired magnetic nanoparticles microextraction

Efficient separation of deoxyribonucleic acid (DNA) through magnetic nanoparticles (MN) is a widely used biotechnology. Hedgehog-inspired MNs (HMN) possess a high-surface-area due to the distinct burr-like structure of hedgehog, but there is no report about the usage of HMN for DNA extraction. Herein, to improve the selection of MN and illustrate the performance of HMN for DNA separation, HMN and silica-coated Fe3O4 nanoparticles (Fe3O4@SiO2) were fabricated and compared for the high-efficient separation of pathogenic bacteria of DNA. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are typical Gram-negative and Gram-positive bacteria and are selected as model pathogenic bacteria. To enhance the extraction efficiency of two kinds of MNs, various parameters, including pretreatment, lysis, binding and elution conditions, have been optimized in detail. In most separation experiments, the DNA yield of HMN was higher than that of Fe3O4@SiO2. Therefore, a HMN-based magnetic solid-phase microextraction (MSPE) and quantitative real-time PCR (qPCR) were integrated and used to detect pathogenic bacteria in real samples. Interestingly, the HMN-based MSPE combined qPCR strategy exhibited high sensitivity with a limit of detection of 2.0 × 101 CFU mL−1 for E. coli and 4.0 × 101 CFU mL−1 for S. aureus in orange juice, and 2.8 × 102 CFU mL−1 for E. coli and 1.1 × 102 CFU mL−1 for S. aureus in milk, respectively. The performance of the proposed strategy was significantly better than that of commercial kit. This work could prove that the novel HMN could be applicable for the efficient separation of DNA from complex biological samples.