title: Efficient Enrichment and Analyses of Bacteria at Ultralow Concentration with Quick-Response Magnetic Nanospheres.
abstract: Enrichment and purification of bacteria from complex matrices are crucial for their detection and investigation, in which magnetic separation techniques have recently show great application advantages. However, currently used magnetic particles all have their own limitations: Magnetic microparticles exhibit poor binding capacity with targets, while magnetic nanoparticles suffer slow magnetic response and high loss rate during treatment process. Herein, we used a highly controllable layer-by-layer assembly method to fabricate quick-response magnetic nanospheres (MNs), and with Salmonella typhimurium as a model, we successfully achieve their rapid and efficient enrichment. The MNs combined the advantages of magnetic microparticles and nanoparticles. On the one hand, the MNs had a fast magnetic response, and almost 100% of the MNs could be recovered by 1 min attraction with a simple magnetic scaffold. Hence, using antibody conjugated MNs (immunomagnetic nanospheres, IMNs) to capture bacteria hardly generated loss and did not need complex separation tools or techniques. On the other hand, the IMNs showed much excellent capture capacity. With 20 min interaction, almost all of the target bacteria could be captured, and even only one bacterium existing in the samples was not missed, comparing with the immunomagnetic microparticles which could only capture less than 50% of the bacteria. Besides, the IMNs could achieve the same efficient enrichment in complex matrices, such as milk, fetal bovine serum, and urine, demonstrating their good stability, strong anti-interference ability, and low nonspecific adsorption. In addition, the isolated bacteria could be directly used for culture, polymerase chain reaction (PCR) analyses, and fluorescence immunoassay without a release process, which suggested our IMNs-based enrichment strategy could be conveniently coupled with the downstream identification and analysis techniques. Thus, the MNs provided by this work showed great superiority in bacteria enrichment, which would be a promising tool for bacteria detection and investigation.
authors.affiliation: College of Science, China University of Petroleum (East China) , Qingdao, 266580, P. R. China.|Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University , Wuhan 430072, P. R. China.
authors.forename: Cong-Ying
authors.initials: CY
authors.lastname: Wen
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University , Wuhan 430072, P. R. China.|Hubei Provincial Center for Disease Control and Prevention , Wuhan 430072, P. R. China.
authors.forename: Yong-Zhong
authors.initials: YZ
authors.lastname: Jiang
authors.affiliation: College of Science, China University of Petroleum (East China) , Qingdao, 266580, P. R. China.
authors.forename: Xi-You
authors.identifier: http://orcid.org/0000-0003-2548-2053
authors.initials: XY
authors.lastname: Li
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University , Wuhan 430072, P. R. China.
authors.forename: Man
authors.initials: M
authors.lastname: Tang
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University , Wuhan 430072, P. R. China.
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: Wu
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University , Wuhan 430072, P. R. China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Hu
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University , Wuhan 430072, P. R. China.
authors.forename: Dai-Wen
authors.initials: DW
authors.lastname: Pang
authors.affiliation: College of Science, China University of Petroleum (East China) , Qingdao, 266580, P. R. China.
authors.forename: Jing-Bin
authors.identifier: http://orcid.org/0000-0002-6179-8867
authors.initials: JB
authors.lastname: Zeng
mesh_terms: D000818:Animals; D018189:Immunomagnetic Separation; D008892:Milk; D054118:Nanospheres; D012486:Salmonella typhimurium
keywords: bacteria; downstream analyses; efficient capture; magnetic nanospheres; quick-response