Unit for Analytical Probes and Protein Biotechnology, Key Laboratory of Clinical Laboratory Diagnostics of the Education Ministry, College of Laboratory Medicine, Chongqing Medical University, Chongqing, People's Republic of China.
Int J Nanomedicine. 2013;8:791-807. doi: 10.2147/IJN.S41411. Epub 2013 Feb 25.
Magnetic submicron particles (MSPs) are pivotal biomaterials for magnetic separations in bioanalyses, but their preparation remains a technical challenge. In this report, a facile one-step coating approach to MSPs suitable for magnetic separations was investigated.
Polyethylene glycol) (PEG) was derived into PEG-bis-(maleic monoester) and maleic monoester-PEG-succinic monoester as the monomers. Magnetofluids were prepared via chemical co-precipitation and dispersion with the monomers. MSPs were prepared via one-step coating of magnetofluids in a water-in-oil microemulsion system of aerosol-OT and heptane by radical co-polymerization of such monomers.
The resulting MSPs contained abundant carboxyl groups, exhibited negligible nonspecific adsorption of common substances and excellent suspension stability, appeared as irregular particles by electronic microscopy, and had submicron sizes of broad distribution by laser scattering. Saturation magnetizations and average particle sizes were affected mainly by the quantities of monomers used for coating magnetofluids, and steric hindrance around carboxyl groups was alleviated by the use of longer monomers of one polymerizable bond for coating. After optimizations, MSPs bearing saturation magnetizations over 46 emu/g, average sizes of 0.32 μm, and titrated carboxyl groups of about 0.21 mmol/g were obtained. After the activation of carboxyl groups on MSPs into N-hydroxysuccinimide ester, biotin was immobilized on MSPs and the resulting biotin-functionalized MSPs isolated the conjugate of streptavidin and alkaline phosphatase at about 2.1 mg/g MSPs; streptavidin was immobilized at about 10 mg/g MSPs and retained 81% ± 18% (n = 5) of the specific activity of the free form.
The facile approach effectively prepares MSPs for magnetic separations.
磁性亚微米颗粒（MSP）是生物分析中磁性分离的关键生物材料，但它们的制备仍然是一个技术挑战。本报告研究了一种适用于磁性分离的 MSP 的简便一步涂层方法。
聚乙二醇（PEG）衍生为 PEG-双（马来酸单酯）和马来酸单酯-PEG-琥珀酸单酯作为单体。通过化学共沉淀和单体分散制备磁流体。通过气溶胶-OT 和庚烷的水包油微乳液体系中的自由基共聚，在一步涂覆磁流体制备 MSP。
所得 MSP 含有丰富的羧基，对常见物质的非特异性吸附可忽略不计，具有优异的悬浮稳定性，电子显微镜下呈不规则颗粒状，激光散射显示亚微米尺寸分布较宽。饱和磁化强度和平均粒径主要受用于涂覆磁流体的单体用量影响，使用较长的单官能团聚合物单体进行涂覆可减轻羧基周围的空间位阻。经过优化，得到了具有超过 46 emu/g 的饱和磁化强度、平均粒径为 0.32 μm、滴定羧基约 0.21 mmol/g 的 MSP。将 MSP 上的羧基活化成 N-羟基琥珀酰亚胺酯后，将生物素固定在 MSP 上，所得生物素功能化 MSP 可将链霉亲和素和碱性磷酸酶的缀合物在约 2.1 mg/g MSP 处分离；将链霉亲和素固定在约 10 mg/g MSP 上，保留游离形式 81%±18%（n=5）的比活性。
该简便方法有效地制备了用于磁性分离的 MSP。
