Labeling cells with superparamagnetic iron oxide (SPIO) nanoparticles provides the ability to track cells by magnetic resonance imaging. Quantifying intracellular iron concentration in SPIO labeled cells would allow for the comparison of agents and techniques used to magnetically label cells. Here we describe a rapid spectrophotometric technique (ST) to quantify iron content of SPIO-labeled cells, circumventing the previous requirement of an overnight acid digestion. Following lysis with 10% sodium dodecyl sulfate (SDS) of magnetically labeled cells, quantification of SPIO doped or labeled cells was performed using commonly available spectrophotometric instrument(s) by comparing absorptions at 370 and 750 nm with correction for turbidity of cellular products to determine the iron content of each sample. Standard curves demonstrated high linear correlation (R(2) = 0.998) between absorbance spectra of iron oxide nanoparticles and concentration in known SPIO-doped cells. Comparisons of the ST with inductively coupled plasma-mass spectroscopy (ICP-MS) or nuclear magnetic resonance relaxometric (R(2)) determinations of intracellular iron contents in SPIO containing samples resulted in significant linear correlation between the techniques (R(2) vs ST, R(2) > 0.992, p < 0.0001; ST vs ICP-MS, R(2) > 0.995, p < 0.0001) with the limit of detection of ST for iron = 0.66 µg ml(-1) for 10(6) cells ml(-1). We have developed a rapid straightforward protocol that does not require overnight acid digestion for quantifying iron oxide content in magnetically labeled cells using readily available analytic instrumentation that should greatly expedite advances in comparing SPIO agents and protocols for labeling cells.

中文翻译：

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用于量化用超顺磁性氧化铁纳米颗粒标记的细胞中铁的快速分光光度法技术：可能转化为临床。

用超顺磁性氧化铁 (SPIO) 纳米粒子标记细胞提供了通过磁共振成像跟踪细胞的能力。量化 SPIO 标记细胞中的细胞内铁浓度将允许比较用于磁性标记细胞的试剂和技术。在这里，我们描述了一种快速分光光度法 (ST) 来量化 SPIO 标记细胞的铁含量，从而避免了先前对过夜酸消化的要求。用 10% 十二烷基硫酸钠 (SDS) 对磁性标记细胞进行裂解后，使用常用的分光光度计通过比较 370 和 750 nm 处的吸收并校正细胞产物的浊度来对掺杂或标记的细胞进行定量每个样品的铁含量。标准曲线表明氧化铁纳米颗粒的吸收光谱与已知 SPIO 掺杂细胞中的浓度之间存在高线性相关性 (R(2) = 0.998)。将 ST 与电感耦合等离子体质谱 (ICP-MS) 或核磁共振弛豫 (R(2)) 测定的含有 SPIO 的样品中的细胞内铁含量进行比较，导致这些技术之间存在显着的线性相关性（R(2) 与ST，R(2) > 0.992，p < 0.0001；ST vs ICP-MS，R(2) > 0.995，p < 0.0001) 铁的 ST 检测限 = 0.66 µg ml(-1) for 10( 6）细胞毫升（-1）。