Department of Nanobiotechnology/Biophysics, Faculty of Biological Science, Tarbiat Modares University, Tehran, 14115-154, Iran.
Mikrochim Acta. 2017 Dec 18;185(1):60. doi: 10.1007/s00604-017-2600-x.
The authors describe a novel water-soluble, stable, biocompatible, and highly fluorescent probe consisting of iron quantum clusters incorporated into human adult hemoglobin (Hb-FeQCs). The Hb-FeQCs were characterized by various spectroscopic techniques. The probe displays strong absorption and yellow fluorescence with a peak centered at 567 nm (photo-excited at 460 nm). The Hb-FeQCs show excellent photostability over a wide range of pH values (5-12), even in the presence of high electrolyte concentrations. A colorimetric and a fluorometric method were worked out for the quantitation Zn(II) and cysteine in aqueous solution. Zinc ions induce a visible color change from brown to yellow. The sensitivity of Hb-FeQCs towards other metal ions was negligible, with the exception of Co and Cu, which caused a modest interference. The Hb-FeQCs were exploited in a sensitive and selective turn-on fluorescence assay for Zn. It is also found that cysteine quenches the fluorescence of the Hb-FeQCs/Zn(II) complex. Under the optimized conditions, the probe has a linear response in the 0.04 to 2.2 μM Zn(II) concentration range, with a 48 nM detection limit. Response to cysteine is linear in the 1-60 μM concentration range, with a 0.25 μM limit of detection. This fluorescent probe undergoes fluorescent emission intensity enhancement upon binding to zinc ions in living normal human fibroblast cells under visible lamp. The cellular imaging capability and very low cytotoxicity of this soluble iron quantum clusters can be potentially extended as an exciting sub-nanoplatform with promising biomaterial applications. Graphical abstract Schematic of yellow-emitting iron quantum clusters in hemoglobin matrix (Hb-FeQCs) were characterized and successfully applied for sensing zinc(II) and cysteine. The act as an on-off fluorescent probe and can be applied to image zinc ions in human fibroblast cells under visible light.
作者描述了一种新型的水溶性、稳定、生物相容和高荧光探针，由嵌入人成年血红蛋白 (Hb-FeQCs) 的铁量子簇组成。Hb-FeQCs 通过各种光谱技术进行了表征。该探针具有强烈的吸收和黄色荧光，峰值位于 567nm（460nm 光激发）。Hb-FeQCs 在很宽的 pH 值范围内（5-12）具有出色的光稳定性，即使在存在高电解质浓度的情况下也是如此。建立了用于定量测定水溶液中 Zn(II) 和半胱氨酸的比色法和荧光法。锌离子诱导从棕色到黄色的可见颜色变化。Hb-FeQCs 对其他金属离子的敏感性可以忽略不计，除了 Co 和 Cu，它们会引起适度的干扰。Hb-FeQCs 被用于灵敏和选择性的 Zn 荧光开启测定法。还发现半胱氨酸猝灭 Hb-FeQCs/Zn(II) 配合物的荧光。在优化条件下，该探针在 0.04 至 2.2 μM Zn(II) 浓度范围内具有线性响应，检测限为 48 nM。对半胱氨酸的响应在 1-60 μM 浓度范围内呈线性，检测限为 0.25 μM。这种荧光探针在可见光下与锌离子结合后，在活的正常人成纤维细胞中，荧光发射强度增强。这种可溶性铁量子簇的细胞成像能力和极低的细胞毒性可作为一种令人兴奋的亚纳米平台，具有广阔的生物材料应用前景。
图 1. 血红蛋白基质中发射黄色荧光的铁量子簇 (Hb-FeQCs) 的示意图，对其进行了表征，并成功应用于检测锌 (II) 和半胱氨酸。作为一种开-关荧光探针，可用于在可见光下对人成纤维细胞中的锌离子进行成像。
