Browsing by Author "Lee, Chia-Hui"

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DNA sequencing using electrical conductance measurements of a DNA polymerase
(2013-06-01)
Chen, Yu-Shiun
;
Lee, Chia-Hui
;
Hung, Meng-Yen
;
Pan, Hsu-An
;
Chiou, Jin-Chern
The development of personalized medicine-in which medical treatment is customized to an individual on the basis of genetic information-requires techniques that can sequence DNA quickly and cheaply. Single-molecule sequencing technologies, such as nanopores, can potentially be used to sequence long strands of DNA without labels or amplification, but a viable technique has yet to be established. Here, we show that single DNA molecules can be sequenced by monitoring the electrical conductance of a phi29 DNA polymerase as it incorporates unlabelled nucleotides into a template strand of DNA. The conductance of the polymerase is measured by attaching it to a protein transistor that consists of an antibody molecule (immunoglobulin G) bound to two gold nanoparticles, which are in turn connected to source and drain electrodes. The electrical conductance of the DNA polymerase exhibits well-separated plateaux that are similar to 3 pA in height. Each plateau corresponds to an individual base and is formed at a rate of similar to 22 nucleotides per second. Additional spikes appear on top of the plateaux and can be used to discriminate between the four different nucleotides. We also show that the sequencing platform works with a variety of DNA polymerases and can sequence difficult templates such as homopolymers.
DNA sequencing using electrical conductance measurements of a DNA polymerase (Retracted article. See vol. 10, pg. 563, 2015)
(2013-06-01)
Chen, Yu-Shiun
;
Lee, Chia-Hui
;
Hung, Meng-Yen
;
Pan, Hsu-An
;
Chiou, Jin-Chern
The development of personalized medicine-in which medical treatment is customized to an individual on the basis of genetic information-requires techniques that can sequence DNA quickly and cheaply. Single-molecule sequencing technologies, such as nanopores, can potentially be used to sequence long strands of DNA without labels or amplification, but a viable technique has yet to be established. Here, we show that single DNA molecules can be sequenced by monitoring the electrical conductance of a phi29 DNA polymerase as it incorporates unlabelled nucleotides into a template strand of DNA. The conductance of the polymerase is measured by attaching it to a protein transistor that consists of an antibody molecule (immunoglobulin G) bound to two gold nanoparticles, which are in turn connected to source and drain electrodes. The electrical conductance of the DNA polymerase exhibits well-separated plateaux that are similar to 3 pA in height. Each plateau corresponds to an individual base and is formed at a rate of similar to 22 nucleotides per second. Additional spikes appear on top of the plateaux and can be used to discriminate between the four different nucleotides. We also show that the sequencing platform works with a variety of DNA polymerases and can sequence difficult templates such as homopolymers.
DNA sequencing using electrical conductance measurements of a DNA polymerase (Retracted article. See vol. 10, pg. 563, 2015)
(2013-06-01)
Chen, Yu-Shiun
;
Lee, Chia-Hui
;
Hung, Meng-Yen
;
Pan, Hsu-An
;
Chiou, Jin-Chern
The development of personalized medicine-in which medical treatment is customized to an individual on the basis of genetic information-requires techniques that can sequence DNA quickly and cheaply. Single-molecule sequencing technologies, such as nanopores, can potentially be used to sequence long strands of DNA without labels or amplification, but a viable technique has yet to be established. Here, we show that single DNA molecules can be sequenced by monitoring the electrical conductance of a phi29 DNA polymerase as it incorporates unlabelled nucleotides into a template strand of DNA. The conductance of the polymerase is measured by attaching it to a protein transistor that consists of an antibody molecule (immunoglobulin G) bound to two gold nanoparticles, which are in turn connected to source and drain electrodes. The electrical conductance of the DNA polymerase exhibits well-separated plateaux that are similar to 3 pA in height. Each plateau corresponds to an individual base and is formed at a rate of similar to 22 nucleotides per second. Additional spikes appear on top of the plateaux and can be used to discriminate between the four different nucleotides. We also show that the sequencing platform works with a variety of DNA polymerases and can sequence difficult templates such as homopolymers.
Gold nanoparticles regulate the blimp1/pax5 pathway and enhance antibody secretion in B-cells
(2014-03-28)
Lee, Chia-Hui
;
Syu, Shih-Han
;
Chen, Yu-Shiun
;
Hussain, Saber M.
;
Onischuk, Andrei Aleksandrovich
Nanoparticles are potential threats to human health and the environment; however, their medical applications as drug carriers targeting cancer cells bring hope to contemporary cancer therapy. As a model drug carrier, gold nanoparticles (GNPs) have been investigated extensively for in vivo toxicity. The effect of GNPs on the immune system, however, has rarely been examined. Antibody-secreting cells were treated with GNPs with diameters ranging from 2 to 50 nm. The GNPs enhanced IgG secretion in a size-dependent manner, with a peak of efficacy at 10 nm. The immune-stimulatory effect reached a maximum at 12 h after treatment but returned to control levels 24 h after treatment. This enhancing effect was validated ex vivo using B-cells isolated from mouse spleen. Evidence from RT-PCR and western blot experiments indicates that GNP-treatment upregulated B-lymphocyte-induced maturation protein 1 (blimp1) and downregulated paired box 5 (pax5). Immunostaining for blimp1 and pax5 in B-cells confirmed that the GNPs stimulated IgG secretion through the blimp1/pax5 pathway. The immunization of mice using peptide-conjugated GNPs indicated that the GNPs were capable of enhancing humoral immunity in a size-dependent manner. This effect was consistent with the bio-distribution of the GNPs in mouse spleen. In conclusion, in vitro, ex vivo, and in vivo evidence supports our hypothesis that GNPs enhance humoral immunity in mouse. The effect on the immune system should be taken into account if nanoparticles are used as carriers for drug delivery. In addition to their toxicity, the immune-stimulatory activity of nanoparticles could play an important role in human health and could have an environmental impact.
The spatial and temporal control of cell migration by nanoporous surfaces through the regulation of ERK and integrins in fibroblasts
(2013-01-01)
Pan, Hsu-An
;
Liang, Jia-You
;
Hung, Yao-Ching
;
Lee, Chia-Hui
;
Chiou, Jin-Chern
Nanotopography controls cell behaviours, such as cell adhesion and migration. However, the mechanisms responsible for topology-mediated cellular functions are not fully understood. A variety of nanopores was fabricated on 316L stainless steel to investigate the effects of spatial control on the growth and function of fibroblasts, the temporal regulation of integrins, and their effects on migration. The NIH-3T3 fibroblast cell line was cultured on the nanopore surfaces, whose pore diameters ranged from 40 to 210 nm. The 40 and 75 nm nanopores enhanced cell proliferation, focal adhesion formation and protein expression of vinculin and beta-tubulin after 24 h of incubation. Integrin expression was analysed by qPCR, which showed the extent of spatial and temporal regulation achieved by the nanopores. The protein expression of pERK1/2 was greatly attenuated in cells grown on 185 and 210 nm nanopore surfaces at 12 and 24 h. In summary, the 40 and 75 nm nanopore surfaces promoted cell adhesion and migration in fibroblasts by controlling the temporal expression of integrins and ERK1/2. The current study provides insight into the improvement of the design of stainless steel implants and parameters that affect biocompatibility. The ability to regulate the expression of integrin and ERK1/2 using nanopore surfaces could lead to further applications of surface modification in the fields of biomaterials science and tissue engineering. (C) 2012 Elsevier Ltd. All rights reserved.
Topographical control of cell-cell interaction in C6 glioma by nanodot arrays
(2014-05-21)
Lee, Chia-Hui
;
Cheng, Ya-Wen
;
Huang, G. Steven
;
材料科學與工程學系
;
分子醫學與生物工程研究所
Nanotopography modulates the physiological behavior of cells and cell-cell interactions, but the manner of communication remains unclear. Cell networking ( syncytium) of astroglia provides the optimal microenvironment for communication of the nervous system. C6 glioma cells were seeded on nanodot arrays with dot diameters ranging from 10 to 200 nm. Cell viability, morphology, cytoskeleton, and adhesion showed optimal cell growth on 50-nm nanodots if sufficient incubation was allowed. In particular, the astrocytic syncytium level maximized at 50 nm. The gap junction protein Cx43 showed size-dependent and time-dependent transport from the nucleus to the cell membrane. The transport efficiency was greatly enhanced by incubation on 50-nm nanodots. In summary, nanotopography is capable of modulating cell behavior and influencing the cell-cell interactions of astrocytes. By fine-tuning the nanoenvironment, it may be possible to regulate cell-cell communications and optimize the biocompatibility of neural implants.