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147 results on '"Kong, S.K."'

10. Improving the sensitivity limit of surface plasmon resonance biosensors by detecting mixed interference signals

Author

Yuan, W., Ho, H.P., Suen, Y.K., Kong, S.K., and Lin, Chinlon

Subjects
Biosensors -- Properties, Biosensors -- Design and construction, Structural optimization -- Methods, Plasmons (Physics) -- Observations, Astronomy, Physics
Abstract

We demonstrate that the sensitivity limit of intensity-based surface plasmon resonance (SPR) biosensors can be enhanced when we combine the effects of the phase and amplitude contributions instead of detecting the amplitude variation only. Experimental results indicate that an enhancement factor of as much as 20 times is achievable, yet with no compromise in measurement dynamic range. While existing SPR biosensor systems are predominantly based on the angular scheme, which relies on detecting intensity variations associated with amplitude changes only, the proposed scheme may serve as a direct system upgrade approach for these systems. The new measurement scheme may therefore lead to a strong impact in the design of SPR biosensors. OCIS codes: 240.6680, 240.6690.

Published
2007

11. Two-dimensional biosensor arrays based on surface plasmon resonance phase imaging

Author

Wong, C.L., Ho, H.P., Yu, T.T., Suen, Y.K., Chow, Winnie W.Y., Wu, S.Y., Law, W.C., Yuan, W., Li, W.J., Kong, S.K., and Lin, Chinlon

Subjects
Biosensors -- Design and construction, Biosensors -- Research, Astronomy, Physics
Abstract

We present a biosensor design based on capturing the two-dimenstional (2D) phase image of surface plasmon resonance (SPR). This 2D SPR imaging technique may enable parallel label-free detection of multiple analytes and is compatible with the microarray chip platform. This system uses our previously reported differential phase measurement approach, in which 2D phase maps obtained from the signal (P) and reference (S) polarizations are compared pixel by pixel. This technique greatly improves detection resolution as the subtraction step can eliminate measurement fluctuations caused by external disturbances as they essentially appear in both channels. Unlike conventional angular SPR systems, in which illumination from a range of angles must be used, phase measurement requires illumination from only one angle, thus making it well suited for 2D measurement. Also, phase-stepping introduced from a moving mirror provides the necessary modulation for accurate detection of the phase. In light of the rapidly increasing need for fast real-time detection, quantification, and identification of a range of proteins for various biomedical applications, our 2D SPR phase imaging technique should hold a promising future in the medical device market. OCIS codes: 240.6680, 170.0110.

Published
2007

12. The nuclear tubular invaginations are dynamic structures inside the nucleus of HeLa cells (1)

Author

Lee, Rebecca K.Y., Lui, Pauline P.Y., Ngan, Erika K.S., Lui, Julian C.K., Suen, Y.K., Chan, Franky, and Kong, S.K.

Subjects
Cell nuclei -- Research, HeLa cells -- Research, Biological sciences, Research
Abstract

Abstract: Nuclear tubules (NTs) were found in the nucleus of HeLa cells. Although no function has been ascribed to these structures, our previous data has shown that they are the [...]

Published
2006

13. cGMP abolishes agonist-induced [[Ca.sup.2+]sub.i] oscillations in human bladder epithelial cells

Author

Kwan, H.Y., Huang, Y., Kong, S.K., and Yao, X.

Subjects
Protein kinases -- Physiological aspects, Inositol -- Physiological aspects, Guanosine -- Physiological aspects, Epithelial cells -- Physiological aspects, Biological sciences
Abstract

Kwan, H. Y., Y. Huang, S. K. Kong, and X. Yao. cGMP abolishes agonist-induced [[Ca.sup.2+].sub.i] oscillations in human bladder epithelial cells. Am J Physiol Renal Physiol 281: F1067-F1074, 2001. First published August 9, 2001; 10.1152/ajprenal.00031.2001.--Cytosolic calcium oscillations may permit cells to respond to information provided by increases in intracellular [Ca.sup.2+] concentration ([[Ca.sup.2+]sub.i]) while avoiding prolonged exposure to constantly elevated [[Ca.sup.2+]sub.i]. In this study, we demonstrated that agonists could induce [Ca.sup.2+] oscillations in human bladder epithelial cells. Application of 10 [micro]M acetylcholine or 200 nM bradykinin triggered an initial [Ca.sup.2+] transient that was followed by periodic [[Ca.sup.2+]sub.i] oscillations. The oscillations did not depend on extracellular [Ca.sup.2+]. 8-Bromoguanosine 3',5'-cyclic monophosphate abolished acetylcholine- or bradykinin-induced oscillations. Elevation of cellular cGMP by dipyridamole, an inhibitor of cGMP-specific phosphodiesterase, also terminated the [[Ca.sup.2+]sub.i] oscillations. The inhibitory effect of cGMP could be reversed by KT-5823, a highly specific inhibitor of protein kinase G (PKG), suggesting that the action of cGMP was mediated by PKG. Comparison of the effect of cGMP with that of xestospongin C, an inhibitor of the inositol 1,4,5-trisphosphate (I[P.sub.3]) receptor, revealed similarities between the action of cGMP and xestospongin C. Therefore, it is likely that cGMP and PKG may target a signal transduction step(s) linked to I[P.sub.3] receptor-mediated [Ca.sup.2+] release. protein kinase G; inositol 1,4,5-triphosphate; calcium release; nitric oxide; intracellular calcium concentration; guanosine 3',5'-cyclic monophosphate Received 5 February 2001; accepted in final form 23 July 2001

Published
2001

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