A versatile and automated microfluidic platform for a quantitative magnetic bead based protocol: application to gluten detection.

A microfluidic platform for the integration of multi-step biological assays has been developed. The presented system is a unique instrument compatible with microfluidic chips for various applications based on bead manipulation. Two examples of microfluidic cartridges are presented here. The first one contains two rows of eight chambers (40 and 80 µL), six reagent inlets, eight testing solution (calibrators and samples) inlets and eight outlets to reproduce precisely each step of a biological assay. This configuration is versatile enough to integrate many different biological assays and save a lot of development time. The second architecture is dedicated to one specific protocol and is completely automated from the standard and sample dilutions to the optical detection. Linear dilutions have been integrated to prepare automatically a range of standard concentrations and outlets have been modified for integrated colorimetric detection. The technology uses pneumatically collapsible chambers to perform all the fluidic operations for a fully automated protocol such as volume calibrations, fluid transport, mixing, and washing steps. A programmable instrument with a software interface has been developed to adapt rapidly a protocol to this cartridge. As an example, these new microfluidic cartridges have been used to successfully perform an immunoassay for gluten detection in the dynamic range of 10-30 ppm with good sensitivity (2 ppm) and specificity.

Optical detection of the magnetophoretic transport of superparamagnetic beads on a micromagnetic array.

Micromagnetic arrays (MMAs) have proven to be powerful tools for controlling the transport and separation of bioanalytes, i.e., they allow bioanalyte-superparamagnetic (SPM) bead complexes of specific size and magnetization to be moved in a synchronized manner that is precisely controlled with the orientation of an external magnetic field. This article presents a laser-photodetector system for the simple detection of individual SPM beads moving on a specific region of an MMA. This system detects the SPM beads through the change in intensity of reflective light as they move from the highly reflective micromagnetics to the supporting substrate. We demonstrate that this opti-MMA system allowed the size, number, and magnetic and optical properties of the SPM beads to be rapidly determined for regions > 49 µm2 in size. The response of the opti-MMA system was characterized in several optical configurations to develop a theoretical description of its sensitivity and dynamic range. The speed, low-cost, and sensitivity of this system promises to allow MMAs to be readily applied in in vitro diagnostics and biosensing.

Separation of Biological Particles in a Modular Platform of Cascaded Deterministic Lateral Displacement Modules.

Deterministic lateral displacement (DLD) has been extensively implemented in the last decade for size-based sample preparation, owing to its high separation performances for a wide range of particle dimensions. However, separating particles from 1 µm to 10 µm in one single DLD device is challenging because of the required diversity of pillar dimensions and inherent fabrication issues. This paper presents an alternative approach to achieve the extraction of E. coli bacteria from blood samples spiked with prostate cancer cells. Our approach consists in cascading individual DLD devices in a single automated platform, using flexible chambers that successively collect and inject the sample between each DLD stage without any external sample manipulation. Operating DLD separations independently enables to maximize the sorting efficiency at each step, without any disturbance from downstream stages. The proposed two-step automated protocol is applied to the separation of three types of components (bacteria, blood particles and cancer cells), with a depletion yield of 100% for cancer cells and 93% for red blood cells. This cascaded approach is presented for the first time with two DLD modules and is upscalable to improve the dynamic range of currently available DLD devices.

Healthy start: description of a safety net for perinatal support during disaster recovery.

Publicly funded programs and safety net organizations have key roles during post disaster recovery to care for vulnerable populations, including pregnant women with low resources. The objective of this study was to compare the health of prenatal women who accessed the New Orleans Healthy Start program to those women who only used traditional prenatal care (PNC) during long-term recovery from the Hurricane Katrina disaster. During 2010-2012, this descriptive, cross-sectional study recruited 402 prenatal women (24-40 weeks) from prenatal clinics and classes. All women were enrolled in PNC, with 282 experiencing only traditional PNC, while 120 women added Healthy Start participation to their usual PNC. Measures were obtained to determine, past hurricane experience, hurricane recovery, perceptions of prenatal care, mental health, and birth outcomes. Women accessing Healthy Start-New Orleans were more socially "at risk" (younger, lower income, not living with a partner, African American), lived through more hurricane trauma, and had a higher incidence of depression (40 %) and post-traumatic stress disorder (PTSD) (15 %) than women in traditional PNC (29 % depression; 6.1 % PTSD). Women using Healthy Start reported more mental health counseling and prenatal education than did women in only traditional PNC. Birth outcomes were similar in the two groups. The Healthy Start participants with less resources and more mental health difficulties after disaster, represented a more vulnerable population in need of additional support. This study underscores the necessity for community and governmental programs to develop disaster response plans that address needs of vulnerable populations during prolonged recovery.