Browsing by Author "Weng, Mao-Feng"

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Cellular uptake and phototoxicity of surface-modified fluorescent nanodiamonds
(2012-02-01)
Weng, Mao-Feng
;
Chang, Bo-Jui
;
Chiang, Su-Yu
;
Wang, Niann-Shiah
;
Niu, Huan
Bioconjugated fluorescent nanodiamonds (FNDs) show potential for effectively targeted imaging and the enhanced photokilling of cancer cells. In this study, we investigated the mechanisms involved in the cellular uptake of surface-modified 140 nm FNDs and evaluated their cytotoxicity and phototoxicity following particle internalization. Through an analysis of flow cytometry, the internalized FND-Tf and FND-NH2 particles reached their respective saturation values, with half-life times of approximately 0.8 h and 1.4 h. The determination indicated that the receptor-mediated endocytosis of FND-Tf particles was highly effective and nearly twice as efficient as the endocytic process of FND-NH2 particles mainly through surface electrostatic interactions. The cytotoxicity of internalized particles was evaluated using the MU assay, indicating that at saturation concentrations, the rate of proliferation of FND-treated cells decreases to less than half that of untreated cells. An examination of the phototoxicity of internalized FND-Tf particles under irradiation using a 532 nm laser revealed that the FND-treated cells could be killed using less than half the energy required for untreated cells. The enhanced cellular killing was attributed to FND particles converting light to thermal energy, with the support of Raman spectra of nanodiamond clusters that showed an increase in particle temperature under irradiation. Our results demonstrated that bioconjugated FNDs could be highly effective in the targeting of cancer cells for fluorescence imaging and photokilling with a minimum of collateral cell damage. (C) 2011 Elsevier B.V. All rights reserved.
Fluorescent nanodiamonds for specifically targeted bioimaging: Application to the interaction of transferrin with transferrin receptor
(2009-02-01)
Weng, Mao-Feng
;
Chiang, Su-Yu
;
Wang, Niann-Shiah
;
Niu, Huan
;
應用化學系
Fluorescent nanodiamonds (FND)as specifically targeted probes to image the interactions of transferrins (TF) with their receptors that were over-expressed on HeLa cells were studied in this work. The 100-nm diamonds were irradiated with a 2.5-MeV ion beam and thermally annealed to emit bright fluorescence in the region 550-800 nm upon excitation at 514.5 nm; accordingly, the interference of cellular autofluorescence at 520-650 nm was eliminated significantly on detecting fluorescence at >660 nm. FND-Tf bioconjugates were produced via the formation of an amide bond between carboxylated FND and transferrin and used to target transferrin receptors (TfR) on HeLa cells for activity testing. The receptor-mediated uptake of FND-Tf bioconjugates into HeLa cells was confirmed from confocal fluorescence images; in contrast, the uptake of FND-Tf bioconjugates on presaturated receptors or carboxylated FND on HeLa cells was unobserved. We measured also the fluorescence spectra and lifetimes of carboxylated FND, FND-Tf bioconjugates and FND-Tf-TfR complexes for characterization. Their measured lifetimes are 11.8 +/- 0.1, 11.6 +/- 0.1 and 12.+/- 0.1 ns, respectively. and fluorescence spectra are comparable except that the two zero-phonon lines of FND-Tf-TfR complexes become indistinct. Both results show that the surface effects of chemical interactions on the emission center of FND are negligible. (C) 2008 Elsevier B.V. All rights reserved.