Qian, H. S., Guo, H. C., Ho, P. C. L., Mahendran, R. & Zhang, Y. Mesoporous-silica-coated up-conversion fluorescent nanoparticles for photodynamic therapy. Small 5, 2285-2290

Division of Bioengineering, Faculty of Engineering, National University of Singapore, Singapore 117574, Singapore.
Small (Impact Factor: 8.37). 10/2009; 5(20):2285-90. DOI: 10.1002/smll.200900692
Source: PubMed

ABSTRACT Near-infrared (NIR)-to-visible up-conversion fluorescent nanoparticles have potential to be used for photodynamic therapy (PDT) in deep tissue because NIR light can penetrate thick tissue due to weak absorption in the optical window. Here a uniform layer of mesoporous silica is coated onto NaYF(4) up-converting nanocrystals, with a large surface area of approximately 770 m(2) g(-1) and an average pore size of 2 nm. A photosensitizer, zinc phthalocyanine, is incorporated into the mesoporous silica. Upon excitation by a NIR laser, the nanocrystals convert NIR light to visible light, which further activates the photosensitizer to release reactive singlet oxygen to kill cancer cells. The photosensitizer encapsulated in mesoporous silica is protected from degradation in the harsh biological environment. It is demonstrated that the photosensitizers loaded into the porous silica shell of the nanoparticles are not released out of the silica while they continuously produce singlet oxygen upon excitation by a NIR laser. The nanoparticles are reusable as the photosensitizers encapsulated in the silica are removed by soaking in ethanol.

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Available from: Huichen Guo, Sep 28, 2015
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    • "following a literature procedure reported [32]. The particles were resuspended in cyclohexane. "
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    ABSTRACT: Recent advances in NIR triggering upconversion-based photodynamic therapy have led to substantial improvements in upconversion-based nanophotosensitizers. How to obtain the high efficiency of singlet oxygen generation under low 980 nm radiation dosage still remains a challenge. A highly efficient nanophotosensitizer, denoted as UCNPs-ZnPc, was constructed for photodynamic therapy, which is based on near infrared (NIR) light upconversion nanoparticle (UCNP) and Zn(II)-phthalocyanine (ZnPc) photosensitizer (PS). The high (1)O2 production efficiency came from the enhancement of the 660 nm upconversion emission of NaYF4:Yb(3+), Er(3+) UCNP with 25% Yb(3+) doping, covalent assemblage of UCNP and ZnPc which significantly shortened the distance and enhanced the energy transfer between the two. The high (1)O2 production led to a secure and efficient PDT treatment, as evidenced by the in vivo test where UCNPs-ZnPc of 50 mg per kg body weight was locally injected into the liver tumor in mice, a low 980 nm radiation dose of 351 J/cm(2) (0.39 W/cm(2)) and short irradiation duration of 15 min were sufficient to perform image-guided PDT and caused the liver tumor inhibitory ratio of approximately 80.1%. Histological analysis revealed no pathological changes and inflammatory response in heart, lung, kidney, liver or spleen.
    Biomaterials 02/2014; 35(13). DOI:10.1016/j.biomaterials.2014.01.068 · 8.56 Impact Factor
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    • "To facilitate the tracking of silica or silica-coated nanoparticles in a biological system, it is common to label silica particles with a fluorophore. This can be an organic dye molecule, which is loaded through either physical adsorption or chemical conjugation; alternatively, a nanoparticle fluorophore--for instance a quantum dot 21 or a upconversion nanoparticle 22, 23--can be used, in which case the particles are encapsulated by a silica shell. These fluorophore-doping methods however, can be time-consuming and expensive, and are commonly associated with issues like high toxicity, increased particle size, and dye-leaking 21, 24, 25. "
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    ABSTRACT: We report herein a straightforward and label-free approach to prepare luminescent mesoporous silica nanoparticles. We found that calcination at 400 °C can grant mesoporous organosilica nanoparticles with strong fluorescence of great photo- and chemical stability. The luminescence is found to originate from the carbon dots generated from the calcination, rather than the defects in the silica matrix as was believed previously. The calcination does not impact the particles' abilities to load drugs and conjugate to biomolecules. In a proof-of-concept study, we demonstrated that doxorubicin (Dox) can be efficiently encapsulated into these fluorescent mesoporous silica nanoparticles. After coupled to c(RGDyK), the nanoconjugates can efficiently home to tumors through interactions with integrin αvβ3 overexpressed on the tumor vasculature. This calcination-induced luminescence is expected to find wide applications in silica-based drug delivery, nanoparticle coating, and immunofluorescence imaging.
    Theranostics 08/2013; 3(9):650-7. DOI:10.7150/thno.6668 · 8.02 Impact Factor
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    • "However, the use of bulk mesoporous silica in many applications suffers from many limitations, especially in the targeted drug delivery mechanisms as carrier and drug kinetics marker in the pharmacological research [9,10]. Recently, luminescent metal-doped mesoporous materials, which can be tracked or monitored to evaluate the efficiency of the drug release, have become a research hotspot [1-3,11-14]. The integration of luminescent metal-doped nanocrystals with mesoporous silica to form core-shell structures is undoubtedly of great value because mesoporous shells not only offer high surface area for derivation of numerous functional groups but also provide accessible large pore channels for the adsorption and encapsulation of biomolecules and even functional nanoparticles. "
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    ABSTRACT: Luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres were synthesized through W/O microemulsion process at ambient temperature. The negatively charged silica favors a coating of the positively charged Tb3+ composite. Thus, silicon layer was adsorbed on the surface of Tb(OH)3 groups to form Tb-O-Si through electrostatic interaction. X-ray diffraction, field emission transmission electron microscopy (FE-TEM), energy-dispersive X-ray spectrometry, and Fourier transform infrared, UV/Visible, and photoluminescence spectroscopies were applied to examine the phase purity, crystallinity, surface morphology, and optical properties of the core-shell nanospheres. The FE-TEM results have revealed typically ordered mesoporous characteristics of the material with monodisperse spherical morphology in a narrow size distribution. The luminescent mesoporous core-shell nanospheres exposed remarkable splitting with broadening in the emission transition 5D4 [rightwards arrow] 7F5 (543 nm). In addition, the luminescent mesoporous core-shell nanospheres emit strong green fluorescence (from Tb3+) in the middle of the visible region under 325 nm (3.8) excitation. The luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres can therefore be exploited as fluorescent probes in biomarkers or biolabeling, optical sensing, and drug delivery system. Further, these nanospheres could have potential use as scattering layers in dye-sensitized solar cells.
    Nanoscale Research Letters 04/2013; 8(1):163. DOI:10.1186/1556-276X-8-163 · 2.78 Impact Factor
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