Affinity capture using vancomycin-bound magnetic nanoparticles for the MALDI-MS analysis of bacteria
Affinity capture using vancomycin-bound magnetic nanoparticles for the MALDI-MS analysis of bacteria
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DOI：
10.1021/ac048990k
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发表时间：
2005-03-15
影响因子：
7.4
通讯作者：
Chen, YC
中科院分区：
文献类型：
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作者：
Lin, YS;Tsai, PJ;Chen, YC
基质辅助激光解吸/电离质谱法（MALDI-MS）提供了一种基于质谱指纹识别区分微生物种类的简单方法。然而，感染样品中的病原体细胞浓度通常低于MALDI-MS直接检测到的浓度。此外，生物体液中蛋白质或代谢物的存在总会对微生物种类的鉴定造成不可避免的干扰。万古霉素与革兰氏阳性菌细胞壁上的D-Ala-D-Ala基团结合，从而抑制肽聚糖的合成，是最有效的抗生素之一。因此，我们采用万古霉素修饰的磁性纳米颗粒作为亲和探针，从样品溶液中选择性地捕获革兰氏阳性病原体；也就是说，这些细菌可以通过施加磁场从样品溶液中分离出来。然后用MALDI-MS对分离的细胞进行表征。由于万古霉素对细胞壁的D-Ala-D-Ala单位具有很高的特异性，这种方法有效地减少了革兰氏阳性菌质谱中蛋白质和代谢物信号的干扰。我们在尿液样本（3ml）中检测到的腐生葡萄球菌和金黄色葡萄球菌的最低细胞浓度相似于7 × 10(4) cfu/mL。
Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) provides a straightforward means to differentiate microorganism species based on mass spectral fingerprinting. The pathogen cell concentration in an infected sample, however, is generally lower than that capable of being detected directly by MALDI-MS. Furthermore, the presence of proteins or metabolites in biological fluids always causes unavoidable interference for the identification of microorganism species. Vancomycin, which binds to D-Ala-D-Ala moieties on the cell walls of Gram-positive bacteria and, therefore, inhibits peptidoglycan synthesis, is one of the most potent antibiotics. Thus, we have employed vancomycin-modified magnetic nanoparticles as affinity probes to selectively trap Gram-positive pathogens from sample solutions; i.e., these bacteria can be isolated from sample solutions by applying a magnetic field. The isolated cells could then be characterized by MALDI-MS. This approach effectively reduces the interference of protein and metabolite signals in the mass spectra of Gram-positive bacteria because vancomycin has such high specificity for the D-Ala-D-Ala units of the cell walls. The lowest cell concentration we detected for both Staphylococcus saprophyticus and Staphylococcus aureus in a urine sample (3 mL) was similar to 7 x 10(4) cfu/mL.