Supporting Information. Bright YAG:Ce nanorod phosphors prepared via a partial wet. chemical route and biolabeling applications

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1 Supporting Information Bright YAG:Ce nanorod phosphors prepared via a partial wet chemical route and biolabeling applications Daidong Guo, a Baojin Ma, a Lili Zhao, a Jichuan Qiu, a Wei Liu, a Yuanhua Sang, a,* Jerome Claverie, b Hong Liu a,* a State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong , China b NanoQAM Research Center, Department of Chemistry, University of Quebec at Montreal, 2101 rue Jeanne-Mance, CP 8888, Montreal, Quebec H3C3P8, Canada. Corresponding authors: sangyh@sdu.edu.cn (Y. Sang); hongliu@sdu.edu.cn (H. Liu) S-1

2 S1. Evaluation process of yield We used raw materials in stoichiometric to prepare the YAG:Ce precursor and phosphors. Normally, the yield (η) can be calculated from the theoretical mass of product YAG:Ce and experimental mass of YAG:Ce by the following equation (Eq. 1): 100% Eq. 1,where m o is represented as the theoretical mass of the product can be calculated from the mass of raw materials, and m is the mass of final product, which was weighted from the calcined nanoparticles. S2. Phase of YAG:Ce phosphors Fig. S1. XRD patterns of the phosphors (a) Granular YAG: 2 at % Ce 3+ ; (b) Granular YAG: 6 at % Ce 3+ ; (c) YAG: 2 at % Ce 3+ nanorod; (d) YAG: 6 at % Ce 3+. Stars indicate Al 2 O 3, and dots indicate CeO 2. From Fig. S1, the diffraction peaks of both YAG: 2 at % Ce 3+ phosphors can be identified as S-2

3 pure Y 3 Al 5 O 12 (JCPDS card: no ). No impurity or obvious shifting of the peaks can be detected from their XRD patterns, which implies that the YAG:Ce-precursor has fully transformed into YAG:Ce. Because of the difficulty in high Ce 3+ doping concentration in YAG: 6 at% Ce 3+ phosphor, some very week diffractions peaks can be detected, which can be ascribed to α-al 2 O 3 phase and CeO 2 phase. The residual Al 2 O 3 and CeO 2 are of very small amount. S3. Synthesis of Al 2 O 3 precursor nanorod Fig. S2. Morphologies and XRD patterns of Al 2 O 3 precursor at different time from hydrothermal process. Al 2 O 3 precursor after (a)1 h hydrothermal reaction; (b) 3 h hydrothermal reaction; (c) 5 h hydrothermal reaction at 150 o C. Inset is the morphology of the Al 2 O 3 precursor nanorod tips. The morphologies of Al 2 O 3 precursor at different time from hydrothermal process were characterized by SEM as shown in Fig. S2. At the first hour of the hydrothermal reaction, Al-compounds primary particles, which are created by reaction between Al 3+ and precipitant S-3

4 groups hydrolyzed from urea, aggregate together. During the last reaction hours, these unstable particles assemble into rod-like Al 2 O 3 -precursor, which is identified as NH 4 Al(OH) 2 CO 3 (JCPDS card no ). At the same time, the rod-like Al 2 O 3 -precursor grow both in length and diameter, and the crystallinity get better and better. The above results confirm the preparation process of the Al 2 O 3 precursor nanorod. S3. Synthesis of granular YAG:Ce phosphors Fig. S3. Morphologies of (a) YAG:Ce granular precursor; (b) Core-shell structure of the precursor; (c) YAG:Ce granular phosphors; and XRD patterns of (d)i YAG:Ce precursor; (d)ii YAG:Ce phosphors. The morphologies of granular YAG:Ce samples were characterized by SEM and TEM as shown in Fig. S3. The YAG:Ce granular precursor mainly consists of subsphaeroidal particles with a size of around 200 nm and a rough surface. As the YAG:Ce precursor nanorod, the S-4

5 YAG:Ce granular precursor also exhibit a clear interface between the Al 2 O 3 core and the Y-compound shell. After calcination, the YAG:Ce granular phosphors is of similar with the granular precursor. But the size of YAG:Ce granular phosphors ( nm) is larger than that of the granular precursor, which is due to the aggregation and agglomeration of the nanoparticles. As well as the XRD pattern of YAG:Ce nanorod samples, the phase of granular YAG:Ce samples transform from the α-al 2 O 3 and amorphous Y-compounds to pure Y 3 Al 5 O 12. Therefore, the partial wet chemical route for granular YAG:Ce samples is the same as YAG:Ce nanorod samples, but with different morphologies and microstructure. S4. Properties of YAG:Ce phosphors Table S1. Surface area of the YAG:Ce phosphors determined by BET method BET surface area / m 2 g 1 Granular YAG: 2 at % Ce Granular YAG: 6 at % Ce YAG: 2 at % Ce 3+ nanorod 8.89 YAG: 6 at % Ce 3+ nanorod 9.58 The surface area of YAG:Ce 3+ nanorod, which is below 10 m 2 g 1, is smaller than that of granular YAG:Ce, which is around 15 m 2 g 1, determined by BET method. Meanwhile, the size of YAG:Ce 3+ nanorod is a length of around 3-5 µm and a diameter of about nm, and the size of granular YAG:Ce 3+ phosphors is nm. We can see that the surface area of the samples increases when the size decreases. S-5

6 Average fluorescence lifetimes were calculated using follow equation (Eq. 2): 1 Eq. 2 And the results are shown in Table S2: Table S2. Average fluorescence lifetimes of YAG:Ce nanorod phosphors τ i /ns Rel % τ I /ns YAG: 2 at % Ce 3+ nanorod YAG: 6 at % Ce 3+ nanorod S-6

7 Fig. S4. Proliferation of BMMSC in the solution with different YAG: 6at%Ce nanorod phosphors concentration after 12, 24, 48 hours. YAG: 6at%Ce nanorod phosphors in the µg ml 1 concentration range have no significant toxic effect on BMMSC within 48 hours except higher phosphors concentration; and in a certain concentration range of phosphors, which is below 100 µg ml 1, the cell compatibility of YAG: 6at%Ce nanorod is excellent and will not lead to hemolysis. S-7

8 Fig. S5. PL stability vs time (0, 12, 24, 48 h) of YAG:Ce nanorods when the material was dispersed in aqueous solution and in PBS buffer and mixed with biological cells. (The values of PL intensity were normalized. The PL intensity of nanorod phosphors in aqueous solution at the beginning (at 0 h) was set as 1, which was the initial value.) YAG: 6at%Ce nanorod phosphors with 100 µg ml 1 was dispersed in aqueous solution, in PBS buffer with BMMSC and in PBS buffer. After incubating the cells with 12, 24 and 48 h, the PL intensity of nanorod phosphors shows good stability. It means that luminescent properties of YAG:Ce nanorod phosphors would not be influenced by PBS buffer and the cells in application. References 1. Fišerová, E.; Kubala, M., Mean Fluorescence Lifetime and Its Error. J. Lumin. 2012, 132 (8), S-8