Nanyang Technological University, Division of Bioengineering, School of Chemical and Biomedical Engineering, Singapore 637457.
J Biomed Opt. 2012 Jan;17(1):017005. doi: 10.1117/1.JBO.17.1.017005.
Hemozoin is a by-product of malaria infection in erythrocytes, which has been explored as a biomarker for early malaria diagnosis. We report magnetic field-enriched surface-enhanced resonance Raman spectroscopy (SERRS) of β-hematin crystals, which are the equivalent of hemozoin biocrystals in spectroscopic features, by using magnetic nanoparticles with iron oxide core and silver shell (Fe(3)O(4)@Ag). The external magnetic field enriches β-hematin crystals and enhances the binding between β-hematin crystals and magnetic nanoparticles, which provides further improvement in SERRS signals. The magnetic field-enriched SERRS signal of β-hematin crystals shows approximately five orders of magnitude enhancement in the resonance Raman signal, in comparison to about three orders of magnitude improvement in the SERRS signal without the influence of magnetic field. The improvement has led to a β-hematin detection limit at a concentration of 5 nM (roughly equivalent to 30 parasites/μl at the early stages of malaria infection), which demonstrates the potential of magnetic field-enriched SERRS technique in early malaria diagnosis.
血晶是疟原虫感染红细胞的一种副产物，已被探索作为早期疟疾诊断的生物标志物。我们报告了使用具有氧化铁核和银壳的磁性纳米粒子（Fe(3)O(4)@Ag）对β-血晶进行磁场富集表面增强共振拉曼光谱（SERRS）的研究，β-血晶在光谱特征上与血晶生物晶体等效。外加磁场富集了β-血晶晶体，并增强了β-血晶晶体与磁性纳米粒子之间的结合，从而进一步提高了 SERRS 信号。与没有磁场影响时的 SERRS 信号相比，磁场富集β-血晶晶体的 SERRS 信号在共振拉曼信号中增强了约五个数量级，而在 SERRS 信号中增强了约三个数量级。这种改进使得β-血晶的检测限达到了 5 nM 的浓度（大致相当于疟疾感染早期每微升 30 个寄生虫），这表明磁场富集 SERRS 技术在早期疟疾诊断中的潜力。
