Microdevice based on centrifugal effect and bifurcation law for separation of plasma from on-line diluted whole blood.

In recent decades, scientific interest in the development of devices capable of performing routine clinical analyses through the application of standardized traditional laboratory protocols in a miniaturized lab-on-a-chip device has increased. In the present work, an innovative microdevice for the on-line whole blood dilution with a phosphate buffer solution (PBS) and separation of plasma was designed, manufactured, and characterized. The microdevice was constructed with a rectangular cross-section and spiral-shaped microchannels by photolithography and soft litography. Also, the widths of the diluted plasma and the remaining blood outlet microchannels were different to create a difference in the outlet flow rates to facilitate and achieve the plasma separation based on the combination of centrifugal effect (Dean drag force) and bifurcation law (Zweifach-Fung effect). The separation purity (α) under the separation conditions (total flow rates between 25 and 100 µL/min, entrance flow rate ratio PBS/whole blood between 4 and 10, and hematocrit (% HCT) between 3 and 8) was around 100% for fresh blood samples, while the separation efficiency (ß) was between 8 and 13%. The concentration in the separated diluted plasma was between 0.1 and 0.7% (v/v) with plasma flow rates between 3 and 7 µL/min, respectively. The quality of the diluted and separated plasma from micordevice was corroborated from a blood sample from a patient diagnosed with rheumatoid arthritis through the quantification of anti-cyclic citrullinated peptide (anti-CCP) antibodies employing a microdevice immunoassay. The developed microdevice has a high potential to be coupled with the on-line detection of biomarkers.

Rapid, Sensitive, and Selective Detection of H5 Hemagglutinin from Avian Influenza Virus Using an Immunowall Device.

Avian influenza virus (AIV) infection, caused by influenza virus type A, is an infectious, acute respiratory disease of birds related to influenza outbreaks worldwide. The highly pathogenic AIV subtype H5N1 has crossed species barriers to infect mammals, including humans, with fatal outcomes and has received attention as a potential pandemic threat. A rapid and timely detection in poultry is vitally important to prevent the virus spread. Despite their great sensitivity, conventional detection methods such as real-time reverse transcription-polymerase chain reaction and the agar gel precipitation test are time-consuming and labor-intensive and require special training. In this work, an immunowall device was evaluated as an easier and faster way for detecting AIV H5-hemagglutinin (AIV H5-HA). For detection, fluorescence-labeled or enzyme-labeled antibody was employed as a labeling antibody in a sandwich immunoassay. Both were shown in this paper to be easier and faster assays for detection compared with the conventional enzyme-linked immunosorbent assay (ELISA) kit. In addition, high selectivity was achieved for AIV H5-HA detection after the evaluation of other different HA virus subtypes. The limit of detection was 0.23 ng/mL for the enzyme-labeled antibody. This value was equivalent to that of the conventional ELISA kit but 8 times faster (31 min compared to 260 min). The detection range was 0.23-100 ng/mL. The immunowall device with the enzyme-labeled antibody offers a rapid, sensitive, selective, and simple immunoassay system for future H5 AIV real sample detection.