Microfluidic On-Chip Cytotoxicity Assay

The whole history of urban life, in a sense,” says Richard Barnett, “is of living with parasites and trying to get rid of them.” There is an ongoing fear – the sense of cities as pregnable entities, susceptible to bacterial invaders, to infections that enter through a port and spread quickly through a population that is living at perilously close quarters. Over the last decades, these fears have flared with the SARS virus, avian flu, and swine flu, each outbreak prompting new concerns about our ability to prevent and treat disease, at a time of greatly increased drug resistance.

In times of such outbreaks, there arises a need to discover drugs, antidotes, and vaccines to control the spread of the associated pathogen as well as treat the affected ones. The current method of testing a potential drug in the laboratory is to perform an MTT Assay after treating the cells with the drug for its cytotoxicity assessment. This method is time taking and requires the researchers to manually (using micropipette) fill the wells of a microtiter plate with a drug of a particular concentration and later perform the assay.

The MTT Cell Proliferation Assay measures the cell proliferation rate and conversely when metabolic events lead to apoptosis or necrosis, the reduction in cell viability. The number of assay steps has been minimized as much as possible to expedite sample processing. The MTT Reagent yields low background absorbance values in the absence of cells. For each cell type, the linear relationship between cell number and signal produced is established, thus allowing accurate quantification of changes in the rate of cell proliferation.

Microfluidics (2)
Figure 1: 3D Printed Mould of the Microfluidic Device (intitial prototype) ©ankitkumar

The current device is designed with multiple cell lines, each having live cells and treated with different concentration of a drug. The concentration gradient across the cell lines is created using a microfluidic gradient generator (The two inlets at the right in the image above are loaded with drug and its solvent respectively) and the left inlet is to pass the buffer/media to flush out the cells once the procedure is completed.

Further, SMD (surface mounted device-type) LEDs will be present above each cell line (outside the PDMS device) having a wavelength of 595 nm and photodiodes opposite to each LED to measure the absorbance. Concentration in each cell line could be calculated using CFD modeling and drop in the voltage at each photodiode can be measured to quantify the efficiency of respective concentrations of the drug.

This method could be useful in the field of drug development as it allows for testing a large number of drugs at different concentrations while using only nanolitres of reagents, thus increasing the efficiency and reducing the cost.

Cells in T Junction
Figure 2: Prostate Cancer Cells Filled inside the Device for Cell Compatibility Test ©ankitkumar
Figure 3: 3D Rendering of the on-chip assay ©ankitkumar
Figure 4: Labelled diagram of the on-chip assay ©ankitkumar

Project Status: Patent filed (India); Application number: 201911036596


1. theguardian.com/cities/2014/feb/24/sick-cities-urban-life-illness-fears 2.atcc.org/~/media/DA5285A1F52C414E864C966FD78C9A79.ashx