Supporting Information

A Fluorescence-Quenching Platform based on

Biomineralized Hydroxyapatite from Natural Seashell

and Applied to Cancer Cell Detection

Ying Zhang,a,b Wei Liu,b Craig E. Banks c, Fei Liu, a Mao Li, a Fan Xia *,a,b , and Xiangliang Yang b

a Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, School of Chemistry & Chemical

Engineering, b National Engineering Research Center for Nanomedicine, College of Life Science and Technology, Huazhong

University of Science and Technology, Wuhan 430074, PR China, c Faculty of Science and Engineering, School of Chemistry

and the Environment, Division of Chemistry and Environmental Science, Manchester Metropolitan University, Chester Street,

Manchester M1 5GD, Lancs, UK

1. Calculation the fractal dimension (Df) of biomineralized substrates:

Df of biomineralized substrates are calculated by the Box-Counting Method,[1] which is widely used for fractal dimension determination. The definition of the box-counting dimension is as follows:[2]

δδ

δ log)(loglim

0 −=

+→

NDB (1)

where DB is the box-counting fractal dimension of the structure, δ is the side length of the box, and N(δ) is the smallest number of boxes of side length δ required to cover completely the outline of the structure being measured. In practice, a group of sample data (－log δ, log N(δ)) can be obtained and the slope of the line is calculated as the estimation of the boxcounting dimension by the least-squares linear regression. The Df of structures in three dimensional space were evaluated as Df = DB+1 as reported previously.[3] In the current work, FractualFox 2.0 was used to calculate the Df of biomineralized substrate based on the calculation principle of Box-Counting method, shown in Fig. S1.

Fig. S1 The relationship between fractal dimension and hydrothermal treatment time (Days) for both the outer and inner surfaces. Wherein, the fractal dimension was calculated by classical Box Counting Method (n>5).

2. Element composition, Ca:P ratio and crystalline phrases evolution EDAX characterization was utilized to investigate the evolution of element composition (Atom %), suggested in Fig. S2. The corresponding Ca:P ratio was also calculated and summarized. Herein, the outer surface of 3 day-HAp exhibiting the highest Ca:P ratio value of 2.62. For exactly identifying the crystalline phrase of the outer and inner surfaces, the XRD measurement was carried out and the patterns are parallelly displayed in Fig. S3.

 

Fig. S2 Element composition and corresponding Ca:P ratio variation trends of natural sea-shell after hydrothermal biomineralization at 160 oC for 3~9 days.

Fig.S3 XRD identification for the crystalline phase in the outer surface (a) and inner surface (b) of sea-shell pieces after hydrothermal treatment for 3~9 days.

 

3. Comparision of Inverted Fluorescence Microscope (IFM) and Laser Scanning Confocal Microscopy (LSCM) images for invalid cell detection by the inner surface of biomimetic substrates

Fig.S4 IFM and LSCM images for invalid cell detection by the inner surface of biomimetic substrates after hydrothermal treated for 3~9 days. The captured cells were stained by DAPI for identification. However, the results should be classified as ineffective.

4. Asymmetrical quenching capability of local regions (obtained after treated for 3~5 days)

Here, Fig.S5~S8 are IFM images from various microscopes for materials obtained after treated for 3~5 days. It can be observed that on the outer surface of material after a hydrothermal treatment both for 3 days and 5 days, most of captured cells existed in the green region, verifing the proposed mechanism that the recovery of FAM fluorophores quenched by the HAp substrates was activated by the cell capture process. Herein, this is more obvious for the substrate after the treatment for 5 days than for 3 days. However, on the contrast, no similar phenomenon occurred on both the inner surfaces, although the cell capture process indeed existed on them. These results confirmed that the asymmetrical queching capability of local regions does not lead to inconsistent results.

Fig.S5 IFM images from various microscope for cell detection by the outer surface of biomimetic substrates after hydrothermal treated for 3 days. The images on the right are amplified regions corresponding to those on the left.

Fig.S6 IFM images from various microscope for cell detection by the inner surface of biomimetic substrates after hydrothermal treated for 3 days. The image on the right is the amplified region corresponding to that on the left.

Fig.S7 IFM images from various microscope for cell detection by the outer surface of biomimetic substrates after hydrothermal treated for 5 days. The images on the right are amplified regions corresponding to those on the left.

Fig.S8 IFM images from various microscope for cell detection by the inner surface of biomimetic substrates after hydrothermal treated for 5 days. The images on the right are amplified regions corresponding to those on the left.

References

[1] Gagnepain, J. J.; Roques-Carmes, C. Wear, 1986, 109, 119. [2] Cross, S. S. J. Pathol. 1997, 182, 1. [3] Mandelbrot, B. B.; Passoja, D. E.; Paullay, A. J. Nature, 1984, 308, 721.