Functional Membrane-Implanted Lab-on-a-Chip for Analysis of Percent HDL Cholesterol

Abstract

A functional lab-on-a-chip has been developed for simultaneous quantitative analyses of high-density lipoprotein (HDL) cholesterol (HDL-C) and total cholesterol (total-C) in a submicroliter plasma sample. The analytical device was fabricated by placing commercial membranes, traditionally used for rapid diagnostics, within microfluidic channels engraved on the surface of a plastic chip. The concentration of HDL-C was measured using enzymatic reactions to produce a colorimetric signal after separation of the single plasma lipoprotein from a mixture. Two small pieces of different membrane pads were used to provide each group of reagents, for HDL separation and enzyme reactions, deposited within their tiny pores in a dry state. To maintain a connection toward the capillary action of the medium, the pads were arranged in a sequence within the fluidic channel that controlled the inlet and outlet of the flow. Upon the addition of a sample, the fluid was delivered through the pads of the chip and a color signal was subsequently generated in proportion to the concentration of HDL-C. The level of total-C was concurrently determined by following identical processes, except absent HDL separation. The two signals were simultaneously determined by employing optical detectors based on transmittance of a light. Such total analyses were completed within 2 min, and the sample sizes were able to be reduced to 0.4 microL for HDL-C and 0.1 microL for total-C, enough to cover the clinically required dynamic ranges.

Lateral flow (immuno)assay: its strengths, weaknesses, opportunities and threats. A literature survey

“…A format that gets a lot of attention these days is the labon-a-chip format [109][110][111][112]. Apart from a much longer development time, the investments are considerable, as the whole microfluidic device has to be designed in advance and prepared using a cleanroom.…”

A microfluidic chip for permeability assays of endothelial monolayer

“…The control of mass transport by means of membranes offered a polarized 3-dimensional environment in-vivo like. Membranes with a large surface area-to-volume ratio enabled ultra-high concentration of analytes for biological applications effectively (Kim et al 2005;Zanzotto et al 2004). In microfluidic devices, diversified membranes including commercial ready-to-use membranes (Abhyankar et al 2006;Diao et al 2006;Chansin et al 2007) and in situ prepared membranes Suzuki et al 2006; were combined into the systems.…”

Review of membranes in microfluidics

“…Pereira–Medrano et al presented a rapid fabrication method of glass/PDMS hybrid micro‐immobilized enzyme reactor for high throughput membrane proteomics . Kim et al presented functional membrane‐implanted lab‐on‐a‐chip for analysis of percentage HDL cholesterol . Hu et al carried out highly efficient extraction and purification of membrane proteins using a microfluidic continuous‐flow based aqueous two‐phase system …”

“…88 Kim et al presented functional membrane-implanted lab-on-a-chip for analysis of percentage HDL cholesterol. 89 Hu et al carried out highly efficient extraction and purification of membrane proteins using a microfluidic continuous-flow based aqueous two-phase system. 90…”