Browsing by Author "Kao, Feng-Sheng"

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Chip-based protein-protein interaction studied by atomic force microscopy
(2012-10-01)
Kao, Feng-Sheng
;
Ger, Waylon
;
Pan, Yun-Ru
;
Yu, Hui-Chen
;
Hsu, Ray-Quen
In this article, a technique for accurate direct measurement of protein-to-protein interactions before and after the introduction of a drug candidate is developed using atomic force microscopy (AFM). The method is applied to known immunosuppressant drug candidate Echinacea purpurea derived cynarin. T-cell/CD28 is on-chip immobilized and B-cell/CD80 is immobilized on an AFM tip. The difference in unbinding force between these two proteins before and after the introduction of cynarin is measured. The method is described in detail including determination of the loading rates, maximum probability of bindings, and average unbinding forces. At an AFM loading rate of 1.44 x 104?pN/s, binding events were largely reduced from 61?+/- 5% to 47?+/-?6% after cynarin introduction. Similarly, maximum probability of bindings reduced from 70% to 35% with a blocking effect of about 35% for a fixed contact time of 0.5?s or greater. Furthermore, average unbinding forces were reduced from 61.4 to 38.9?pN with a blocking effect of similar to 37% as compared with similar to 9% by SPR. AFM, which can provide accurate quantitative measures, is shown to be a good method for drug screening. The method could be applied to a wider variety of drug candidates with advances in bio-chip technology and a more comprehensive AFM database of protein-to-protein interactions. Biotechnol. Bioeng. 2012; 109: 24602467. (c) 2012 Wiley Periodicals, Inc.
Efficacy verification and microscopic observations of an anticancer peptide, CB1a, on single lung cancer cell
(2012-12-01)
Kao, Feng-Sheng
;
Pan, Yun-Ru
;
Hsu, Ray-Quen
;
Chen, Hueih-Min
;
機械工程學系
In this work, we introduce a new customized anti-lung cancer peptide, CB1a, with IC50 of about 25.0 +/- 1.6 mu M on NCI-H460 lung cancer cells. Using a multi-cellular tumor spheroid (MCTS) model, results show that CB1a is potent in preventing the growth of lung cancer tumor-like growths in vitro. Additionally, atomic force microscopy (AFM) was used to examine cell surface damage of a single cancer. The mechanism for cell death under CB1a toxicity was verified as being largely due to cell surface damage. Moreover, with a treatment dosage of CB1a at 25 mu M, Young's module (E) shows that the elasticity and stiffness of cancer cell decreased with time such that the interaction time for a 50% reduction of E (IT50) was about 7.0 min. This new single-cell toxicity investigation using IT50 under AFM assay can be used to separately verify drug efficacy in support of the traditional IC50 measurement in bulk solution. These results could be of special interest to researchers engaged in new drug development. (C) 2012 Elsevier B.V. All rights reserved.
Parallel synthesis and biological evolution of quinic acid derivatives as immuno-suppressing agents against T-cell receptors
(2015-01-01)
Huang, Chih-Yu
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Chen, Li-Hsun
;
Huang, Hsuan-Yu
;
Kao, Feng-Sheng
;
Lee, Yun-Ta
A simple protocol for the synthesis of quinic acid derivatives was established and their biological evolution against T-cells is studied. Results showed that one of the derivatives, Cyn-1324, has low toxicity on T-cells and a high effect on reducing Signal 2 of T-cell immune responses. In vitro binding measurements of atomic force spectroscopy further indicated that the blocking effect of Cyn-1324 between CD28 and CD80 was about 31 + 4%. In vivo animal tests also confirmed that Cyn-1324 can reduce the allergic responses from ovalbumin-induced mice with little toxicity. Based on these observations, Cyn-1324 can be a mild immuno-suppressive candidate for future drug development.