In situ label-free quantification of human pluripotent stem cells with electrochemical potential.

Conventional methods for quantification of undifferentiated pluripotent stem cells such as fluorescence-activated cell sorting and real-time PCR analysis have technical limitations in terms of their sensitivity and recyclability. Herein, we designed a real-time in situ label-free monitoring system on the basis of a specific electrochemical signature of human pluripotent stem cells in vitro. The intensity of the signal of hPSCs highly corresponded to the cell number and remained consistent in a mixed population with differentiated cells.

Large-Scale Nanoelectrode Arrays to Monitor the Dopaminergic Differentiation of Human Neural Stem Cells.

A novel cell-based biosensing platform is developed using a combination of sequential laser interference lithography and electrochemical deposition methods. This enables the sensitive discrimination of dopaminergic cells from other types of neural cells in a completely nondestructive manner. This platform and detection strategy may become an effective noninvasive in situ monitoring tool that can be used to determine stem cell fate for various regenerative applications.

Synthesis of metal nanoparticles inside living human cells based on the intracellular formation process.

Intracellular and extracellular formation of Au and Ag NPs with different sizes and shapes using human cells has been developed as green method, which does not require the use of any reducing agents. Also, the cell lysis is used for production of different metal NPs. Our results demonstrate that treatment of human cells with various metal ions cause cell fixation.

Cell chip with a thiolated chitosan self-assembled monolayer to detect the effects of anticancer drugs on breast normal and cancer cells.

Cell-based chips are an effective in vitro analysis tool; however, the sensitivity of the cell chip to biomaterials is high, which is crucial for immobilizing cells on the electrode surface without conductivity. In this study, we report on a cell chip with a thiolated chitosan monolayer that was easy to fabricate, highly adhesive to cells, and enhanced electrochemical signals. Thiolated chitosan containing thiol groups was synthesized and self-assembled on a gold electrode to immobilize cells, and showed superior electrochemical performance to that of poly-l-lysine and collagen.

In situ electrochemical detection of embryonic stem cell differentiation.

Stem cell sensors have emerged as a promising technique to electrochemically monitor the functional status and viability of stem cells. However, efficient electrochemical analysis techniques are required for the development of effective electrochemical stem cell sensors. In the current study, we report a newly developed electrochemical cyclic voltammetry (CV) system to determine the status of mouse embryonic stem (ES) cells.

Electrochemical cell chip to detect environmental toxicants based on cell cycle arrest technique.

A cell-based chip was recently developed and shown to be an effective in vitro tool for analyzing effect of environmental toxin on target cells. However, common cell chips are inappropriate for the detection of multiple environmental toxins. Here, we fabricated a neural cell chip to detect different cellular responses induced by BPA (bisphenol-A) and PCB (poly chlorinated biphenyl).

Detection of the effect of environmental toxicants on the synthetic peptide modified neural cell chip.

A cell based chip was designed to differentiate and to detect the effects of environmental chemicals on the neurite outgrowth in PC12 cell. To fabricate platform of cell chip, gold surfaces were modified by RGD based synthetic oligopeptide. Nanoscale controlled self-assembled peptide layer was investigated by Atomic Force Microscopy (AFM).

Surface-enhanced Raman scattering of dopamine on self-assembled gold nanoparticles.

Dopamine, a potent neurotransmitter in the brain, influences a variety of motivated behaviors and plays a major role in Parkinson's disease. In this study, the Raman signal of dopamine was detected on a fabricated nanoparticle-immobilized glass surface by surface-enhanced raman spectroscopy (SERS). Amine-modified glass was prepared by the self-assembly of amine-terminated silane on substrate, followed by the deposition of gold nanoparticles.

Fabrication of gold nanoparticle modified ITO substrate to detect beta-amyloid using surface-enhanced Raman scattering.

Alzheimer's disease is a progressive neurodegenerative disorder that is characterized by the deposition of beta-amyloid (Abeta) peptide and the formation of neurofibrillary tangles in neurons. The Abeta peptide is a key molecule in the pathogenesis of Alzheimer's disease and an important marker for early diagnosis. Surface-enhanced Raman scattering (SERS) has recently been attracting keen interest in various fields such as for biosensors or immunoassays.

Effects of nanopatterned RGD peptide layer on electrochemical detection of neural cell chip.

The cell-based chip is becoming a popular tool for monitoring living cell viability under various conditions. In this study, several biomaterials, such as synthetic Cys-(Arg-Gly-Asp)(4) (C(RGD)(4)), Arg-Gly-Asp-Multi Armed-Cys (RGD-MAP-C) peptide, and poly-L-lysine (PLL) nano-dots were fabricated on the gold surface of a neural cell chip. The material-dependent effects both on electrochemical signal detection in neural cells and on cellular adhesion were analyzed.

Analysis of effect of nanoporous alumina substrate coated with polypyrrole nanowire on cell morphology based on AFM topography.

In this study, in situ electrochemical synthesis of polypyrrole nanowires with nanoporous alumina template was described. The formation of highly ordered porous alumina substrate was demonstrated with Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). In addition, Fourier transform infrared analysis confirmed that polypyrrole (PP) nanowires were synthesized by direct electrochemical oxidation of pyrrole.

Electrical detection of beta-amyloid (1-40) using scanning tunneling microscopy.

Numerous studies have shown that the presence of beta-amyloid (1-40) in cerebrospinal fluid can be used as a potential biomarker for Alzheimer's disease. Identifying biomarkers for Alzheimer's disease is highly important because these biomarkers could be used to establish the diagnosis before the disease reaches clinical severity. In this study, a vertically configured electrical detection system associated with scanning tunneling microscopy (STM) was used to characterize antigen-antibody binding interactions.

Fabrication of recombinant azurin self-assembled layer for the application of bioelectronic device.

A novel immobilization method of cupredoxin azurin on a gold surface was developed without a chemical linker using recombinant technique. A recombinant protein with cysteine residue by site-directed mutagenesis (SDM) was designed and then directly self-assembled on Au surface. The layer of the functionalized protein immobilized is confirmed by surface plasmon resonance (SPR) and its surface morphology is analyzed by scanning tunneling microscopy (STM).

Cell-based chip for the detection of anticancer effect on HeLa cells using cyclic voltammetry.

HeLa cells directly immobilized on gold-patterned silicon substrate were used to assess the biological toxicity of anticancer drugs (hydroxyurea and cyclophosphamide). Immobilization of HeLa cells was confirmed by optical microscopy, and cell growth, viability and drug-related toxicity were examined by cyclic voltammetry and potentiometric stripping analysis. The voltammetric behaviors of HeLa cells displayed a quasi-reversible pattern with the peak current exhibiting a linear relationship with cell number.

Direct immobilization of cupredoxin azurin modified by site-directed mutagenesis on gold surface.

For making efficient bioelectronic device, we have developed novel immobilization method of cupredoxin azurin modified on gold (Au) surface. A recombinant protein with cysteine residue by using site-directed mutagenesis was designed and then directly immobilized on Au surface without any chemical linker. The immobilization of the functionalized protein is confirmed by surface plasmon resonance (SPR) and its surface morphology is analyzed by scanning tunneling microscopy (STM).

The immobilization of animal cells using the cysteine-modified RGD oligopeptide.

RGD peptide sequence is an effective cell recognition motif and used to enhance the cell adhesion on desired solid material for cell immobilization. We have synthesized CRGD, CRGD-multiple-armed peptide (MAP), RGD-MAP-C and evaluated their comparative efficacy for cell immobilization. Each peptide was assembled on gold surface and investigated by the atomic force microscopy (AFM) technique in the contact mode.