PepS: An Innovative Microfluidic Device for Bedside Whole Blood Processing before Plasma Proteomics Analyses.

Immunoassays have been used for decades in clinical laboratories to quantify proteins in serum and plasma samples. However, their limitations make them inappropriate in some cases. Recently, mass spectrometry (MS) based proteomics analysis has emerged as a promising alternative method when seeking to assess panels of protein biomarkers with a view to providing protein profiles to monitor health status. Up to now, however, translation of MS-based proteomics to the clinic has been hampered by its complexity and the substantial time and human resources necessary for sample preparation. Plasma matrix is particularly tricky to process as it contains more than 3000 proteins with concentrations spanning an extreme dynamic range (1010). To address this preanalytical challenge, we designed a microfluidic device (PepS) automating and accelerating blood sample preparation for bottom-up MS-based proteomics analysis. The microfluidic cartridge is operated through a dedicated compact instrument providing fully automated fluid processing and thermal control. In less than 2 h, the PepS device allows bedside plasma separation from whole blood, volume metering, depletion of albumin, protein digestion with trypsin, and stabilization of tryptic peptides on solid-phase extraction sorbent. For this first presentation, the performance of the PepS device was assessed using discovery proteomics and targeted proteomics, detecting a panel of three protein biomarkers routinely assayed in clinical laboratories (alanine aminotransferase 1, C-reactive protein, and myoglobin). This innovative microfluidic device and its associated instrumentation should help to streamline and simplify clinical proteomics studies.

Long duration stabilization of porous silicon membranes in physiological media: Application for implantable reactors.

The natural biodegradabilty of porous silicon (pSi) in physiological media limits its wider usage for implantable systems. We report the stabilization of porous silicon (pSi) membranes by chemical surface oxidation using RCA1 and RCA2 protocols, which was followed by a PEGylation process using a silane-PEG. These surface modifications stabilized the pSi to allow a long period of immersion in PBS, while leaving the pSi surface sufficiently hydrophilic for good filtration and diffusion of several biomolecules of different sizes without any blockage of the pSi structure. The pore sizes of the pSi membranes were between 5 and 20 nm, with the membrane thickness around 70 µm. The diffusion coefficient for fluorescein through the membrane was 2 × 10-10 cm2 s-1, and for glucose was 2.2 × 10-9 cm2 s-1. The pSi membrane maintained that level of glucose diffusion for one month of immersion in PBS. After 2 months immersion in PBS the pSi membrane continued to operate, but with a reduced glucose diffusion coefficient. The chemical stabilization of pSi membranes provided almost 1 week stable and functional biomolecule transport in blood plasma and opens the possibility for its short-term implantation as a diffusion membrane in biocompatible systems.

Coagulation dynamics of a blood sample by multiple scattering analysis.

We report a new technique to measure coagulation dynamics on whole-blood samples. The method relies on the analysis of the speckle figure resulting from a whole-blood sample mixed with coagulation reagent and introduced in a thin chamber illuminated with a coherent light. A dynamic study of the speckle reveals a typical behavior due to coagulation. We compare our measured coagulation times to a reference method obtained in a medical laboratory.

A minimally invasive microdevice for molecular sampling and analysis.

In this paper, we present a new minimally invasive biopsy microdevice adapted to proteomic mass spectrometry analysis. The concept is born from a multidisciplinary collaboration in fields of proteomics, cancer research, and microtechnology. In mixing different skills, we have developed and manufactured a miniaturized biopsy device using microtechnology techniques in order to minimize tissue damage during surgical gesture. Dedicated chemically functionalized areas were added to the device in order to increase capture yield and specificity during tissue contact. Fields of application range from cancer research to the study of neurodegenerative diseases.