Magnetic harvesting of microalgae by magnetic nanoparticles (MNPs) depends on the interface interactions between microalgal cells and MNPs, therefore it’s important to understand these interface interactions. In this effort, we discussed the application and principles of microalgae magnetic harvesting via MNPs synthesized by the coprecipitation method. MNPs were capable of capturing Nannochloropsis maritima with a harvesting efficiency of 99.5% at a dosage of 0.33 g MNPs/g dry biomass, and the harvesting performance was less dependent on pH values in the range of 5.0–9.0. Treated with ultrasonic chloroform/methanol (2:1, v/v) solvent, the biomass was enriched and MNPs were reactivated and maintained ~60% harvesting effectiveness after 5 cycles. Regardless of the negative zeta potential for both MNPs and microalgae, MNPs-microalgae interactions were explained by surface-enhanced Raman spectroscopy (SERS) and extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory, and phospholipids over microalgal membrane were located as anchors for MNPs adhesion onto the microalgae. This work provided deeper insights into microalgae harvesting by MNPs and offered the powerful SERS technique for unlocking the door to MNPs-microalgae interface interactions.

磁性纳米颗粒（MNP）对微藻的磁性捕集取决于微藻细胞与MNP之间的界面相互作用，因此了解这些界面相互作用非常重要。在这项工作中，我们讨论了通过共沉淀法合成的MNP进行微藻磁收集的应用和原理。MNPs能够捕获海洋拟南芥在0.33 g MNPs / g干生物量的情况下，其收割效率为99.5％，并且收割性能对pH值在5.0-9.0范围内的依赖性较小。用超声氯仿/甲醇（2：1，v / v）溶剂处理后，生物质富集，MNPs重新活化，并在5个循环后保持约60％的收获效率。不管MNP和微藻的负ζ电位如何，都可以通过表面增强拉曼光谱（SERS）和扩展的Derjaguin-Landau-Verwey-Overbeek（EDLVO）理论来解释MNP-微藻之间的相互作用，并将微藻膜上的磷脂定位为锚点MNPs附着在微藻上的能力。这项工作为MNP收集微藻提供了更深入的见解，并提供了强大的SERS技术来为MNP与微藻界面的相互作用打开大门。