CCMB researchers have fabricated a paper-based microfluidic device for rapid determination of lipid profile. Cholesterol and triglycerides can be detected in less than eight minutes and only 10 microlitre of serum sample is needed. The device has to be validated with more blood samples.

A portable, cheap, point-of-care diagnostics for rapid determination of total cholesterol, HDL, LDL and triglycerides in a single run might become a possible with researchers at Centre for Cellular and Molecular Biology (CSIR-CCMB), Hyderabad successfully fabricating a paper-based microfluidic device. The device has high specificity while the sensitivity is comparable with conventional methods. The device has to be validated with more blood samples.

The flower-shaped device with five arms is printed on a filter paper to simultaneously detect total cholesterol, HDL, LDL, and triglycerides; the fifth arm acts as a control. Cholesterol and triglycerides can be detected in less than eight minutes using the microfluidic device. Only 10 microlitre of serum sample is needed to determine the four parameters.

“Sample requirement is less — 10 microlitre of serum. This can be obtained from 25 microlitre of blood,” says Dr. Shahila Parween from CCMB and first of a paper published in the journal Sensors and Actuators B: Chemical.

The filter paper is functionalised with aminosilane (3-aminoproplytriethoxysilane or APTES) and gold nanoparticles. The aminosilane acts as a binder to immobilise both gold nanoparticles and enzymes on the paper surface. While the enzymes react with the serum and help in detecting cholesterol and triglycerides, the gold nanoparticles enhance the intensity of the detection dye to produce a visible change in colour based on the amount of cholesterol and triglycerides present in the sample.

“For quantifying the amount of total cholesterol, HDL, LDL, and triglycerides we should have a readout device. We are trying to collaborate with researchers from another institute who have already developed a readout device,” says Dr. Amit Asthana from CCMB who led the team. Meanwhile, quantification can be done by scanning the paper device and using an image analyser to measure the intensity of colour change in the paper in the reaction zone.

“Till such time we have a readout device, we can use the three colour dots with different intensities present above the reaction zone (where cholesterol and triglycerides are detected) to know if cholesterol and triglycerides levels in the serum are low, medium or high,” says Dr. Parween. “Matching the dye intensity with the colour dots by the naked eye can help in semiquanitification.”

The serum sample added to the sample zone flows into all the five arms to reach the reaction zone present at the end of each arm. The serum has to pass through a narrow channel and a precipitation zone prior to reaching the reaction zone. The precipitation zone has reagents that are coated on the paper. These reagents react with the sample and allow only HDL or LDL to enter the detection zone in the case of the arms meant for HDL and LDL detection. The precipitation zone is devoid of any reagent in the arms meant for detecting total cholesterol, triglycerides and control.

“The precipitation zone devoid of any enzymes is present even in the three arms meant for detecting total cholesterol, triglycerides and control to keep the flow rate uniform,” says Dr. Asthana.

Published in The Hindu on February 2, 2019