Browsing by Author "Chang, Bo-Jui"

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Cellular uptake and phototoxicity of surface-modified fluorescent nanodiamonds
(2012-02-01)
Weng, Mao-Feng
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Chang, Bo-Jui
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Chiang, Su-Yu
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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.
Measurement of the adhesive force between a single Klebsiella pneumoniae type 3 fimbria and collagen IV using optical tweezers
(2006-11-10)
Chang, Bo-Jui
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Huang, Ying-Jung
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Chan, Chia-Han
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Hsu, Long
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Peng, Hwei-Ling
Type 3 fimbriae are important adhesive filaments that assist Klebsiella pneumoniae to establish an infection. Different MrkD adhesin variants on the fimbriae are known to display distinct adherence capability for the bacteria to bind extracellular matrix proteins, although the difference has not been determined physically. For this reason, the adhesive force between type 3 fimbriae and collagen IV were measured using optical tweezers. The measured force data displayed a periodic histogram thus Fourier analysis was applied to group it to extract the adhesive force of a single molecular pair. Specifically, we showed that grouping should begin with an offset at the first half of the period. Finally, we first present the adhesive force between each mrkD(V2)-, mrkD(V3)-, and mrkD(V4)-expressed fimbriae and collagen IV is 2.03, 3.79, and 2.87 pN, respectively, This result can be referred to further research on mrkD allelic effect on bacteria infection. (c) 2006 Elsevier Inc. All rights reserved.
Stepped changes of monovalent ligand-binding force during ligand-induced clustering of integrin alpha(IIB)beta(3)
(2006-09-01)
Hsieh, Chia-Fen
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Chang, Bo-Jui
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Pai, Chyi-Huey
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Chen, Hsuan-Yi
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Tsai, Jin-Wu
Recent evidence demonstrated that conformational changes of the integrin during receptor activation affected its binding to extracellular matrix; however, experimental assessment of ligand-receptor binding following the initial molecular interaction has rarely been carried out at a single-molecule resolution. In the present study, laser tweezers were used to measure the binding force exerted by a live Chinese hamster ovary cell that expressed integrin alpha(IIb)beta(3) (CHO alpha(IIb)beta(3)), to the bead carrier coated with the snake venom rhodostomin that served as an activated ligand for integrin alpha(IIb)beta(3). A progressive increase of total binding force over time was noticed when the bead interacted with the CHO alpha(IIb)beta(3) cell; such an increase was due mainly to the recruitment of more integrin molecules to the bead-cell interface. When the binding strength exerted by a single ligand-receptor pair was derived from the "polyvalent" measurements, surprisingly, a stepped decrease of the "monovalent binding force" was noted (from 4.15 to 2.54 piconewtons (pN)); such decrease appeared to occur during the ligand-induced integrin clustering process. On the other hand, the mutant rhodostomin defective in clustering integrins exhibited only one (1.81 pN) unit binding strength.
Subdiffraction scattered light imaging of gold nanoparticles using structured illumination
(2011-12-15)
Chang, Bo-Jui
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Lin, Shiuan Huei
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Chou, Li-Jun
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Chiang, Su-Yu
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電子物理學系
A reflective light-scattering (RLS) microscope with structured illumination (SI) provides subdiffraction resolution and improves the image quality of gold nanoparticles in biological systems. The three-dimensional (3D)-structured pattern is rapidly and precisely controlled with a spatial light modulator and scrambled at the conjugate image plane to increase spatial incoherence. The reconstructed SI-RLS image of 100nm gold nanoparticles reveals lateral and axial resolutions of approximately 117 and 428nm. We present a high-resolution image of gold nanoparticles inside a HeLa cell, with improved contrast. (C) 2011 Optical Society of America