Application of cell chip for detection of environmental toxicants 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 cell chip to detect different cellular responses. Why we need to use the cell based sensors. • The cell-based biosensors provide a biologically relevant response to toxic compounds and mixtures • Contrary to analytical chemistry methods, nonspecific but integrative detection • They Can be extremely sensitive in some cases • They are not only for environmental sensing, but enormous potential in toxicology screening of chemical and pharmacological compounds

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Application of cell chip for detection of environmental toxicants
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 cell chip to detect different
cellular responses.
Why we need to use the cell based sensors.
• The cell-based biosensors provide a biologically relevant response to toxic compounds
and mixtures
• Contrary to analytical chemistry methods, nonspecific but integrative detection
• They Can be extremely sensitive in some cases
• They are not only for environmental sensing, but enormous potential in toxicology
screening of chemical and pharmacological compounds
Type of cell used
1. Mammalian cell
Characteristics are as fallows
• Non-specific toxicity detection
• Strict incubation conditions
• Already used for in-vitro toxicology screening in pharma research
Challenges
• Find best detection methods
• Micro bioreactor: long term culture, proliferation
• Sampling environment water while keeping good culture conditions
• Question of the variability and reference measurement
2. Bacterial cell
Characteristics are as fallows
 Specificity to chemical compounds
• Easy to incubate
• Already proven in environmental measurements
• No automated instrument yet

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Challenges
• Storage/conditionning, continuous measurement
• Question of the reference or control measurement
• Design or selection of new bacterial genotypes for new chemical compounds
Type of detection
A simple, highly sensitive cell-chip based electrochemical tool for the toxicity assessment of
various chemicals, environmental toxicants or nanomaterials. A neural cell-chip was fabricated
on RGD-MAP-C modified Au surface to assess toxicity of CdSe/ZnS on intracellular redox
environment SH-SY5Y cell. The SH-SY5Y cell immobilized working electrode were established
on a silicon surface by DC magnetron sputtering and a platinum and standard silver electrode
were also place as counter. The electrochemical measurements were performed using CHI
potentiostat instrument; the Ipc and Ipa from SH-SY5Y cell were measured at 250 mV and 365
mV, respectively. Variations of current peak intensities from CdSe/ZnS treated and non-treated
SH-SY5Y cell were considered as a parameter for the cytotoxicity assessment.
Figure 1 Schematics for the detection of cytotoxicity of thioglycolic acid (TA) or cysteamine
(CA)-capped green and red quantum dots (QDs) based on cell chip and conventional MTT assay.
“R”, “W” and “C” mean the reference, working, and counter electrodes, respectively.

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Examples
1. Neural cellchip based electrochemicaldetectionofnanontoxicity
Development of a rapid, sensitive and cost-effective method for toxicity assessment of
commonly used nanoparticles is urgently needed for the sustainable development of
nanotechnology. A neural cell with high sensitivity and conductivity has become a potential
candidate for a cell chip to investigate toxicity of environmental influences. A neural cell
immobilized on a conductive surface has become a potential tool for the assessment of
nanotoxicity based on electrochemical methods. The effective electrochemical monitoring
largely depends on the adequate attachment of a neural cell on the chip surfaces. Recently,
establishment of integrin receptor specific ligand molecules arginine-glycine-aspartic acid
(RGD) or its several modifications RGD-Multi Armed Peptide terminated with cysteine (RGD-
MAP-C), C(RGD)4 ensure farm attachment of neural cell on the electrode surfaces either in their
two dimensional (dot) or three dimensional (rod or pillar) like nano-scale arrangement. A three
dimensional RGD modified electrode surface has been proven to be more suitable for cell
adhesion, proliferation, differentiation as well as electrochemical measurement.
Figure 2. Schematic representation of redox phenomena at cell-substrate interface (i) and
the redox peaks obtained from PC12 cell immobilized on peptide fabricated Au electrode (ii);
(iii) cyclic voltammetry (CV) for comparing the electrochemical signal using C(RGD).

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2. Lab on a chip pathogen sensors for food pathogens
There have been a number of cases of foodborne illness among humans that are caused by
pathogens such as Escherichia coli O157:H7, Salmonella typhimurium, etc. The current practices
to detect such pathogenic agents are cell culturing, immunoassays, or polymerase chain reactions
(PCRs). These methods are essentially laboratory-based methods that are not at all real-time and
thus unavailable for early-monitoring of such pathogens. They are also very difficult to
implement in the field. Lab-on-a-chip biosensors, however, have a strong potential to be used in
the field since they can be miniaturized and automated; they are also potentially fast and very
sensitive. These lab-on-a-chip biosensors can detect pathogens in farms, packaging/processing
facilities, delivery/distribution systems, and at the consumer level. There are still several issues
to be resolved before applying these lab-on-a-chip sensors to field applications, including the
pre-treatment of a sample, proper storage of reagents, full integration into a battery-powered
system, and demonstration of very high sensitivity. Several different types of lab-on-a-chip
biosensors, including immunoassay- and PCR-based, have been developed and tested for
detecting foodborne pathogens.
Figure 3 A lab on a chip contains a network of channels and wells.

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3. Microfluidic biosensor for bacterial detection and identification
The microfluidic chip utilizes impedance-based measurement to (1) detect cells and (2) identify
them when used in conjunction with immobilized monoclonal antibodies. Bacteria in suspension
passing through the microfluidic chamber are recognized by antibodies and selectively
immobilized on the functionalized glass surface, thereby increasing the measured impedance
within the chamber. Continuous perfusion of bacteria suspension through the derivatized
chamber not only identifies specific bacteria but also enhances the chamber’s detection
sensitivity by accumulating bacteria on the chamber wall over time; this approach would be
useful for detecting low concentrations of bacteria.
The selectivity of the sensor was tested using a suspension of two bacterial strains, E. coli and M.
catarrhalis. The sensor chip is simple to use, requires minuscule samples, and eliminates
extensive cell culture processes.
Figure 4 microfluidic chip for bacterial cell detection causing toxicity
References
1. http://www.researchgate.net/publication/235002787_On-
chip_microfluidic_biosensor_for_bacterial_detection_and_identification
2. www.mdpi.com/journal/nanomaterials
3. http://www.ncbi.nlm.nih.gov/pubmed/22959010
4. http://www.sciencedirect.com/science/article/pii/S0956566312005477
5. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3472853/