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fluorescence evolution of the KB cells labeled with
NPAFN@SiO2 NPs. Scale bar: 40 µm, excitation wavelength was
488 nm. (c) In vivo fluorescence image of the mice at 12 h after 60 observed for silica-coated NPs than tDhOatI: 1o0f.10u3n9c/oCa3tCeCd47N96P1sG.
injection of the NPAFN@SiO2 NPs. Inset is the fluorescence
5 image of NPs in the storage equipment.
for in vitro and in vivo imaging. Much higher brightness with
Application of core-shell NPs for in vitro and in vivo imaging
was also demonstrated respectively. Systematic in vivo toxicity
study also indicated the biocompatibility of the NPAFN@SiO2
NPs. This work highlights the great potential of the silica-coated
The biocompatible, highly photo- and pH-stable, ultra-bright
NIR fluorescent NPAFN@SiO2 NPs are further explored as 65 dye NPs for high efficient in vitro and in vivo bioimaging.
biological fluorescent probes for in vitro imaging. Fig. 3a shows
10 images of the KB cells imaged with NPAFN NPs and
NPAFN@SiO2 NPs in the same concentration, both stained with
DAPI. The fluorescence of NPAFN@SiO2 NPs labeled KB cells
This work was supported by National Basic Research Program
of China (973 Program, Grant Nos. 2013CB933500,
2012CB932400, 2011CB808400), and National Natural Science
was observed to be particularly bright compared to that of 70 Foundation of China (Nos. 51173124, 51172151). X. J. Hao and
NPAFN NPs at the same concentration, in good accord with the
15 photostability study and cellular uptake result determined by
FACS (Fig. 2b). Based on the high photostability and excellent
biocompatibility of the resultant NPAFN@SiO2 NPs, we further
verify the possibility of utilizing it as fluorescent probe for long-
term imaging. As shown in Fig. 3b, even after 120 min
20 continuous irradiation, the NPAFN@SiO2 NPs preserved a
strikingly stable fluorescence due to the robust photostability,
which is particularly suitable for long-term imaging.
M. J. Zhou contribute equally to this work.
Notes and references
a Functional Nano & Soft Materials Laboratory (FUNSOM) and Jiangsu
75 KSoeoycLhaobwoUrantoivreyrfsoitryC, Saurzbhoonu-B, JaisaendgFsuun2c1t5io1n2a3l, MChaitneari;aTlsel&: 8D6e5v1ic2es,
65889855; E-mail: xjzhang@suda.edu.cn; jsjie@suda.edu.cn
b Nano-organic Photoelectronic Laboratory and Key Laboratory of
Photochemical Conversion and Optoelectronic Materials, Technical
80 I1n0s0ti1t9u0te, CofhPinhay;siTcesl:an8d6 C01h0em82is5tr4y3,5C1h0i;nEe-sme aAicl:adxhemzhyaonfg@Scmieanicle.isp,cB.aecij.icnng
The NPAFN@SiO2 NPs level in the blood was first studied
over time. A blood circulation half-life of 2.5 h was observed for
25 NPAFN@SiO2 NPs as shown in Fig. S5. The NPAFN@SiO2 NPs
were then intravenously injected into 4T1 tumor-bearing BALB/c
mice for in vivo imaging, hair of the mice were removed from
neck to foot. With time went by, accumulation of the NPs in the
tumor site with intense fluorescence was observed. Significantly,
30 even with the exposure time was reduced to 15 ms, after 12 hours
post injection the fluorescent signals of NPAFN@SiO2 NPs were
still distinctively bright and highly spatially resolved, in sharp
contrast to extremely low signals in other parts of the mouse body
even in the hair, which show strong autofluorescence before
35 injection (Fig. S6). And almost no autofluorescence background
detected, as shown in Fig. 3c. Such high signal to noise ratio
(sensitivity) is particularly beneficial for NIR probes for cancer
diagnosis. We then studied the biodistribution of the NPs by
imaging the major organs and the tumor tissues of 4T1 tumor-
40 bearing BALB/c mouse at different post injection time points
(Fig. S7). Consistent with the in vivo imaging results, the
fluorescence of NPs in the tumor tissues increased with time.
After 24 h post injection, prominent accumulation of NPs in
tumor sites were observed (41.1% ID g-1), which were higher
† Electronic Supplementary Information (ESI) available: [details of any
supplementary information available should be included here]. See
DOI:10.1039/b000000x/
85
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55 Conclusions
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We have demonstrated a novel silica-coated dye NP to achieve
highly luminescent and ultraphotostable NIR fluorescent probes
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