Fluorescence enhancement of gold nanoclustersviaZn doping for biomedical applications

Yanqing Qiao,Jing Chen,Junying Wang,Yuan-Ming Sun,Xueting Bai,Yonghui Li,Qiang Liu,Xiaoyu Mu,Lingfang Liu,Meili Guo,Haixia Liu,Ying Liu,Wei Long,Haile Liu,Xiao-Dong Zhang

doi:10.1039/c7ra13072d

Yanqing Qiao, Jing Chen + Show 13 more

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https://doi.org/10.1039/c7ra13072d

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Gold nanoclusters (NCs) have been widely used in bioimaging and cancer therapy due to their unique electronic structures and tunable luminescence. However, their weak fluorescence prevents potential biomedical application, and thus it is necessary to develop an effective route to enhance the fluorescence of gold NCs. In this work, we report the fluorescence enhancement of ultrasmall GSH-protected Au NCs by Zn atom doping. The fluorescence signal of Zn-doped Au NCs shows approximately 5-fold enhancement compared to pure Au NCs. Density functional theory (DFT) calculation shows that Zn doping can enhance the electronic states of the highest occupied molecular orbital (HOMO), leading to enhancement of visible optical transitions. In vitro experiments show that AuZn alloy NCs can enhance the cancer radiotherapy via producing reactive oxygen species (ROS) and don't cause significant cytotoxicity. In vivo imaging indicates AuZn alloy NCs have significant passive targeting capability with high tumor uptake. Moreover, nearly 80% of GSH-protected AuZn alloy NCs can be rapidly eliminated via urine excretion.

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Gold nanoclusters (NCs), have been widely used in biological imaging, cancer therapy, energy and environmental science,[1,2,3,4,5,6,7,8,9,10,11,12] owing to their numerous peculiar features such as unique size[13] and morphology-dependent optical, catalytic, and electronic properties.[14,15,16,17,18] Ultrasmall metal NCs, about 1–3 nm between single atoms and large nanocrystals,[19,20,21] show quantum electronic properties and tunable uorescence, and are expected to be potential candidates for novel uorescent probes
For the pure Au NCs and 10% Zn-doped NCs, only one signi cant peak appears at 525 nm
The absorbance and uorescence of GSH-protected AuZn alloy NCs displays superior stability in biological media such as water and phosphate buffer saline (PBS), and satisfactory photostability without signi cant decay as demonstrated in Fig. S1.† The zeta potential and hydrodynamic diameters of clusters in deionized ultra ltered (DIUF) water or fetal bovine serum (FBS) were determined by dynamic light scattering (DLS) with a NanoZS Zetasizer (Malvern)

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Introduction

Gold nanoclusters (NCs), have been widely used in biological imaging, cancer therapy, energy and environmental science,[1,2,3,4,5,6,7,8,9,10,11,12] owing to their numerous peculiar features such as unique size[13] and morphology-dependent optical, catalytic, and electronic properties.[14,15,16,17,18] Ultrasmall metal NCs, about 1–3 nm between single atoms and large nanocrystals,[19,20,21] show quantum electronic properties and tunable uorescence, and are expected to be potential candidates for novel uorescent probes. The absorbance and uorescence of GSH-protected AuZn alloy NCs displays superior stability in biological media such as water and phosphate buffer saline (PBS), and satisfactory photostability without signi cant decay as demonstrated in Fig. S1.† The zeta potential and hydrodynamic diameters of clusters in deionized ultra ltered (DIUF) water or fetal bovine serum (FBS) were determined by dynamic light scattering (DLS) with a NanoZS Zetasizer (Malvern).

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