Mei Zhong, Dhanale Ashish, Gangaharan Ajithkumar, Sardar Dhiraj Kumar, Tang Liang
Department of Biomedical Engineering, University of Texas at San Antonio, TX 78249, USA.
Department of Physics & Astronomy, University of Texas at San Antonio, TX 78249, USA.
Talanta. 2016 May 1;151:23-29. doi: 10.1016/j.talanta.2016.01.007. Epub 2016 Jan 8.
Magnetic nanoparticles (MNPs) are widely used in biosensing, bioimaging, and drug delivery. However, high quality superparamagnetic nanoparticles with uniform size were usually synthesized by thermal decomposition using organic solvents. To be suitable for biomedical applications, a facile and efficient water dispersion of iron oxide MNPs from solvent using an innovative agent, sodium oleate (NaOL) was described. The monodispersed MNPs (4 and 15nm respectively) after transfer was biocompatible and stable at a broad temperature range (4-50°C) over months. More importantly, the NaOL coating allows for surface modification with selective functionality, rendering the aqueous MNPs highly customizable for biofunctionalization. Little effect on the superparamagnetism was observed after the water dispersion. To further evaluate its practical application in biosensing, custom MNPs were prepared for specific cardiac troponin I (cTnI) detection for myocardial infarction diagnosis. Specifically, gold nanorod (GNR) biochip was probed by the MNP-captured cTnI target analyte at varying concentrations. The signal transduction of the GNR sensor is based on the localized surface plasmon resonance (LSPR). The application of the MNPs resulted in a significant enhancement of the plasmonic response of the GNRs. As such, the MNP-mediated LSPR biosenisng showed a three times lower sensitivity as compared to the direct cTnI binding without functional MNPs. Computer simulation further elucidated that the enhancement was distance dependent between the MNP and the surface of the nanorod, which corroborated with experimental results.
磁性纳米颗粒（MNPs）广泛应用于生物传感、生物成像和药物递送领域。然而，具有均匀尺寸的高质量超顺磁性纳米颗粒通常是通过使用有机溶剂的热分解法合成的。为了适用于生物医学应用，本文描述了一种使用创新试剂油酸钠（NaOL）从溶剂中简便高效地将氧化铁MNPs进行水分散的方法。转移后的单分散MNPs（分别为4和15纳米）具有生物相容性，并且在数月内的宽温度范围（4 - 50°C）内保持稳定。更重要的是，NaOL涂层允许进行具有选择性功能的表面修饰，使水性MNPs在生物功能化方面具有高度可定制性。水分散后对超顺磁性的影响很小。为了进一步评估其在生物传感中的实际应用，制备了定制的MNPs用于特异性检测心肌肌钙蛋白I（cTnI）以诊断心肌梗死。具体而言，通过不同浓度的MNP捕获的cTnI目标分析物对金纳米棒（GNR）生物芯片进行检测。GNR传感器的信号转导基于局部表面等离子体共振（LSPR）。MNPs的应用导致GNRs的等离子体响应显著增强。因此，与没有功能化MNPs的直接cTnI结合相比，MNP介导的LSPR生物传感的灵敏度降低了三倍。计算机模拟进一步阐明，增强作用与MNP和纳米棒表面之间的距离有关，这与实验结果相符。
