Ji-yen Cheng - Academia.edu (original) (raw)

Papers by Ji-yen Cheng

Nucleic acids research, Jan 15, 2002

A 1536 channel oligonucleotide synthesizer, the MultiSyn, was developed with the capability to si... more A 1536 channel oligonucleotide synthesizer, the MultiSyn, was developed with the capability to simultaneously synthesize 1536 oligonucleotides of 20mer length in 10 h. The instrument was designed to synthesize different sequences of various lengths in micro-wells and has synthesized oligonucleotides as long as 119 nt with reasonably good yields using CPG beads of 1000 A pore size. The instrument consists of four 384 channel synthesis modules. Phosphoramidite chemistry was employed and step yields as high as 99.3% were achieved. The enhancement of oligonucleotide synthesis throughput is accomplished by increasing the spatial density of reaction wells. We have identified several parameters that are critical in achieving a good synthesis yield and negligible failure rate in small reaction wells. The coefficient of variation (CV) of product yields in 1536 reaction wells was 20%. The quality of the product was examined by capillary electrophoresis and mass spectrometry. The instrument ha...

ACS applied materials & interfaces, Jan 30, 2015

Organs are composed of heterotypic cells with patterned architecture that enables intercellular i... more Organs are composed of heterotypic cells with patterned architecture that enables intercellular interaction to perform specific functions. In tissue engineering, the ability to pattern heterotypic cells into desired arrangement will allow us to model complex tissues in vitro and to create tissue equivalents for regeneration. This study was aimed at developing a method for fast heterotypic cell patterning with controllable topological manipulation on a glass chip. We found that poly(vinyl alcohol)-coated glass showed a biphasic change in adhesivity to cells in vitro: low adhesivity in the first 24 h and higher adhesivity at later hours due to increased serum protein adsorption. Combining programmable CO2 laser ablation to remove poly(vinyl alcohol) and glass, we were able to create arrays of adhesive microwells of adjustable patterns. We tested whether controllable patterns of epithelial-mesenchymal interaction could be created. When skin dermal papilla cells and fibroblasts were see...

We use structured-illumination nano-profilometry with sub-diffraction-limit lateral resolution to... more We use structured-illumination nano-profilometry with sub-diffraction-limit lateral resolution to measure the filopodium dynamics of lung cancer cells under stimulation of DC electric fields. The cathode growth bias and enhanced expression of filopodia are observed.

2005 3rd IEEE/EMBS Special Topic Conference on Microtechnology in Medicine and Biology, 2005

A novel microfluidic coculture system was developed for more accurately modelling the interaction... more A novel microfluidic coculture system was developed for more accurately modelling the interaction of macrophages and osteoblasts. The microfluidic coculture chip was fabricated by CO 2 laser direct-writing on poly(methyl methacrylate) (PMMA) and was designed to separate two cell types by a microchannel, while permitting cellular media to transfer. The released inflammatory cytokines (ex: IL-1β, TNF-α) activated in upstream macrophages flow through a microfluidic system and generate linear concentration gradients in down-stream wells and induce down-stream osteoblasts to release prostaglandin E2 (PGE2), which is well-known as a bone resorption marker. Colorimetric MTT assay was used to examine the osteoblast viability. This system can be used to evaluate the cell-cell interaction while physically separate the interacting cells.

Journal of the Chinese Chemical Society, 2005

ABSTRACT Different cellular accumulations with distinct fluorescence properties of BMVC in cancer... more ABSTRACT Different cellular accumulations with distinct fluorescence properties of BMVC in cancer cells from normal cells allow us to establish a simple and economic method for the diagnosis of cancer cells. With using a light emitting diode to excite the BMVC molecule, microarray fluorescence analysis of a cell-based glass chip provides an easy method towards the detection of a limited number of cancer cells.

Journal of the Chinese Chemical Society, 1997

ABSTRACT The spectral features of satellite holes are used to investigate 9‐aminoacridine‐DNA int... more ABSTRACT The spectral features of satellite holes are used to investigate 9‐aminoacridine‐DNA interactions. The hole depths of the outer ring vibronic modes are reduced more than that of the inner ring vibronic modes, implying that inner ring motion is less perturbed than outer ring motion. As a result, the mode coupling between the inner ring and outer ring is reduced upon binding to DNA. However, similar hole frequency and width of the satellite hole corresponding to the NH2 mode upon binding to DNA imply that the amino group of 9‐aminoacridine sits outside the DNA.

Conference on Lasers and Electro-Optics 2010, 2010

ABSTRACT We use structured-illumination nano-profilometry with sub-diffraction-limit lateral reso... more ABSTRACT We use structured-illumination nano-profilometry with sub-diffraction-limit lateral resolution to measure the filopodium dynamics of lung cancer cells under stimulation of DC electric fields. The cathode growth bias and enhanced expression of filopodia are observed.

In this work, a material new to reed making, the bamboo, was compared with the traditionally used... more In this work, a material new to reed making, the bamboo, was compared with the traditionally used Arundo donax L. (the cane). The cross-sectional anatomy, relationship between the thickness and the reed strength, the spectral cen-troid, and the effect of the water extraction on the timbre were studied. The moso-bamboo has higher density of fibre inside a vascular bundle but has lower number density of the vascular bundles. For both materials, the reed thickness alone was not a good index for the reed strength. When the reed is new, the moso-bamboo gives brighter sound at the high note. After the sugar extraction by water, the spectral centroid of both materials reduced to lower frequency, in-dicating less bright sound. The cane seems to be more durable when the high note was compared. For the low note, the two materials perform similarly after the sugar extraction..

Biosensors, 2014

Label-free detection of rare cells in biological samples is an important and highly demanded task... more Label-free detection of rare cells in biological samples is an important and highly demanded task for clinical applications and various fields of research, such as detection of circulating tumor cells for cancer therapy and stem cells studies. Surface Plasmon Resonance (SPR) as a label-free method is a promising technology for detection of rare cells for diagnosis or research applications. Short detection depth of SPR (400 nm) provides a sensitive method with minimum interference of non-targets in the biological samples. In this work, we developed a novel microfluidic chip integrated with gold nanoslit SPR platform for highly efficient immunomagnetic capturing and detection of rare cells in human blood. Our method offers simple yet efficient detection of target cells with high purity. The approach for detection consists of two steps. Target cells are firs captured on functionalized magnetic nanoparticles (MNPs) with specific antibody I. The suspension containing the captured cells (...

Talanta, 2015

In this work, electrokinetic acceleration of DNA hybridization was investigated by different comb... more In this work, electrokinetic acceleration of DNA hybridization was investigated by different combinations of frequencies and amplitudes of actuating electric signals. Because the frequencies from low to high can induce different kinds of electrokinetic forces, i.e., electroosmotic to electrothermal forces, this work provides an in-depth investigation of electrokinetic enhanced hybridization. Concentric circular Cr/Au microelectrodes of 350µm in diameter were fabricated on a glass substrate and probe DNA was immobilized on the electrode surface. Target DNA labeled with fluorescent dyes suspending in solution was then applied to the electrode. Different electrokinetic forces were induced by the application of different electric signals to the circular microelectrodes. Local microfluidic vortexes were generated to increase the collision efficiency between the target DNA suspending in solution and probe DNA immobilized on the electrode surface. DNA hybridization on the electrode surface could be accelerated by the electrokinetic forces. The level of hybridization was represented by the fluorescent signal intensity ratio. Results revealed that such 5-min dynamic hybridization increased 4.5 fold of signal intensity ratio as compared to a 1-h static hybridization. Moreover, dynamic hybridization was found to have better differentiation ability between specific and non-specific target DNA. This study provides a strategy to accelerate DNA hybridization in microsystems.

2013 Conference on Lasers and Electro-Optics Pacific Rim (CLEOPR), 2013

ABSTRACT We measured the membrane roughness of neuroblastoma cells by non-interferometric wide-fi... more ABSTRACT We measured the membrane roughness of neuroblastoma cells by non-interferometric wide-field optical profilometry. We found that the peptide related to Alzheimer's disease, Amyloid-beta 42, reduces membrane roughness, but direct-current electrical fields recover this effect.

PLoS ONE, 2013

Physiological electric field (EF) plays a pivotal role in tissue development and regeneration. In... more Physiological electric field (EF) plays a pivotal role in tissue development and regeneration. In vitro, cells under direct-current electric field (dcEF) stimulation may demonstrate directional migration (electrotaxis) and long axis reorientation (electro-alignment). Although the biophysical models and biochemical signaling pathways behind cell electrotaxis have been investigated in numerous normal cells and cancer cells, the molecular signaling mechanisms in CL1 lung adenocarcinoma cells have not been identified. Two subclones of CL1 cells, the low invasive CL1-0 cells and the highly invasive CL 1-5 cells, were investigated in the present study. CL1-0 cells are non-electrotactic while the CL 1-5 cells are anodally electrotactic and have high expression level of epidermal growth factor receptor (EGFR), in this study, we investigated the generally accepted hypothesis of receptor tyrosine kinase (RTK) activation in the two cell lines under dcEF stimulation. Erbitux, a therapeutic drug containing an anti-EGFR monoclonal antibody, cetuximab, was used to investigate the EGFR signaling in the electrotaxis of CL 1-5 cells. To investigate RTK phosphorylation and intracellular signaling in the CL1 cells, large amount of cellular proteins were collected in an airtight dcEF stimulation device, which has advantages of large culture area, uniform EF distribution, easy operation, easy cell collection, no contamination, and no medium evaporation. Commercial antibody arrays and Western blotting were used to study the phosphorylation profiles of major proteins in CL1 cells under dcEF stimulation. We found that electrotaxis of CL 1-5 cells is serum independent and EGFR independent. Moreover, the phosphorylation of Akt and S6 ribosomal protein (rpS6) in dcEF-stimulated CL1 cells are different from that in EGFstimulated cells. This result suggests that CL1 cells' response to dcEF stimulation is not through EGFR-triggered pathways. The new large-scale dcEF stimulation device developed in the present work will aid the sample preparation for protein-based experiments.

Journal of the Chemical Society, Faraday Transactions, 1997

Page 1. Satellite hole investigations of the hole-burning mechanism and vibrational mode coupling... more Page 1. Satellite hole investigations of the hole-burning mechanism and vibrational mode coupling of 9-aminoacridine doped in glycerol–water glasses at di†erent pH values Chien-Chih Chiang,a,b Bor-Chyuan Hwang,a,§ Jenwei ...

ABSTRACT We present a flexible microfluidic channel fabrication platform that can be used to deve... more ABSTRACT We present a flexible microfluidic channel fabrication platform that can be used to develop microfluidic chips. A DPSS (diode pumped solid state) frequency quadrupled (lambda = 266 nm, the UV system) Nd:YAG laser and a CO2 laser (lambda = 10.6 mum, the IR system) are compared for their ablation capability on quartz and glass. We have also compared their performance in developing microfluidic chips. The resultant surface quality, including microcracking, debris, and distortion, is examined by SEM and a surface profiler. In these systems, users design microfluidic patterns by commercial software. The pattern is then transferred to a CNC stage for trenching. The microfabrication process can be completed in several minutes. Without the need to fabricate photomask for patterning, the development time can be reduced from weeks to hours. In addition, the substrate size is not limited by the dimension of the photomask. Asymmetric trenches demonstrating the machining capability of these systems have been fabricated by these systems. The minimal feature for the IR system and the UV system is 140 mum and 5 mum, respectively. These systems are very powerful for rapid glass microfluidic chip development.

Lab Chip, 2015

Environmental contamination has become a serious problem to human and environmental health, as ex... more Environmental contamination has become a serious problem to human and environmental health, as exposure to a wide range of possible contaminants continuously increases due to industrial and agricultural activities. Whole cell sensors have been proposed as a powerful tool to detect class-specific toxicants based upon their biological activity and bioavailability. We demonstrated a robust toxicant detection platform based on a bioluminescence whole cell sensor array biochip (LumiChip). LumiChip harbors an integrated temperature control and a 16-member sensor array, as well as a simple but highly efficient luminescence collection setup. On LumiChip, samples were infused in an oxygen-permeable microfluidic flow channel to reach the sensor array. Time-lapse changes in bioluminescence emitted by the array members were measured on a single window-removed linear charge-coupled device (CCD) commonly used in commercial industrial process control or in barcode readers. Removal of the protective window on the linear CCD allowed lens-free direct interfacing of LumiChip to the CCD surface for measurement with high light collection efficiency. Bioluminescence induced by simulated contamination events was detected within 15 to 45 minutes. The portable LumiSense system utilizing the linear CCD in combination with the miniaturized LumiChip is a promising potential platform for on-site environmental monitoring of toxicant contamination.

Biomedical Optics Express, 2012

Nucleic Acids Research - NAR, 2005

This work describes a novel and simple modification of the current microarray format. It reduces ... more This work describes a novel and simple modification of the current microarray format. It reduces the sample/reagent volume to 1 ml and the hybridization time to 500 s. Both 20mer and 80mer oligonucleotide probes and singly labeled 20mer and 80mer targets, representative of the T-cell acute lymphocytic leuk- emia 1 (TAL1) gene, have been used to elucidate the performance of this hybridization approach. In this format, called shuttle hybridization, a conventional flat glass DNA microarray is integrated with a PMMA microfluidic chip to reduce the sample and reagent consumption to 1/100 of that associated with the conventional format. A serpentine microtrench is designed and fabricated on a PMMA chip using a widely available CO2 laser scriber. The trench spacing is compatible with the inter-spot distance in standard microarrays. The microtrench chip and microarray chip are easily aligned and assembled manually so that the microarray is integrated with a microfluidic channel. Discrete sa...

The Journal of Physical Chemistry B, 1998

We have introduced the satellite hole spectral method to examine the binding sites of 3,3′-diethy... more We have introduced the satellite hole spectral method to examine the binding sites of 3,3′-diethyloxadicarbocyanine cation (DODC + ) to various guanine-rich oligonucleotides. The satellite hole patterns along with normal mode calculations allow us to determine the interaction of DODC + with a dimeric hairpin quadruplex formed by sequence d(G 4 T 4 G 4 ). Our results are consistent with the groove binding model and eliminate the possibility of intercalation in the base pairs of guanine quartet.

The Analyst, 2005

This study develops a novel temperature cycling strategy for executing temperature cycling reacti... more This study develops a novel temperature cycling strategy for executing temperature cycling reactions in laser-etched poly(methylmethacrylate) (PMMA) microfluidic chips. The developed microfluidic chip is circular in shape and is clamped in contact with a circular ITO heater chip of an equivalent diameter. Both chips are fabricated using an economic and versatile laser scribing process. Using this arrangement, a self-sustained radial temperature gradient is generated within the microfluidic chip without the need to thermally isolate the different temperature zones. This study demonstrates the temperature cycling capabilities of the reported microfluidic device by a polymerase chain reaction (PCR) process using ribulose 1,5-bisphosphate carboxylase large subunit (rbcL) gene as a template. The temperature ramping rate of the sample inside the microchannel is determined from the spectral change of a thermochromic liquid crystal (TLC) solution pumped into the channel. The present results confirm that a rapid thermal cycling effect is achieved despite the low thermal conductivity of the PMMA substrate. Using IR thermometry, it is found that the radial temperature gradient of the chip is approximately 2 uC mm 21 . The simple system presented in this study has considerable potential for miniaturizing complex integrated reactions requiring different cycling parameters.