Hydrogel particles-on-chip (HyPoC): a fluorescence micro-sensor array for IgG immunoassay.

Novel microparticles have generated growing interest in diagnostics for potential sensitivity and specificity in biomolecule detection and for the possibility to be integrated in a micro-system array as a lab-on-chip. Indeed, bead-based technologies integrated in microfluidics could speed up incubation steps, reduce reagent consumption and improve accessibility of diagnostic devices to non-expert users. To limit non-specific interactions with interfering molecules and to exploit the whole particle volume for bioconjugation, hydrogel microparticles, particularly polyethylene glycol-based, have emerged as promising materials to develop high-performing biosensors since their network can be functionalized to concentrate the target and improve detection. However, the limitations in positioning, trapping and mainly fine manipulation of a precise number of particles in microfluidics have largely impaired point-of-care applications. Herein, we developed an on-chip sandwich immunoassay for the detection of human immunoglobulin G in biological fluids. The detection system is based on finely engineered cleavable PEG-based microparticles, functionalized with specific monoclonal antibodies. By changing the particle number, we demonstrated tuneable specificity and sensitivity (down to 3 pM) in serum and urine. Therefore, a controlled number of hydrogel particles have been integrated in a microfluidic device for on-chip detection (HyPoC) allowing for their precise positioning and fluid exchange for incubation, washing and target detection. HyPoC dramatically decreases incubation time from 180 minutes to one minute and reduces washing volumes from 3.5 ml to 90 µL, achieving a limit of detection of 0.07 nM (with a dynamic range of 0.07-1 nM). Thus, the developed approach represents a versatile, fast and easy point-of-care testing platform for immunoassays.

PEG-based cleavable hydrogel microparticles with controlled porosity for permiselective trafficking of biomolecular complexes in biosensing applications.

In the last decade, PEG-based hydrogels have been extensively used for the production of microparticles for biosensing applications. The biomolecule accessibility and mass transport rate represent key parameters for the realization of sensitive microparticles, therefore porous materials have been developed, mainly resorting to the use of inert porogens and copolymers with different chain lengths. However, very limited information is reported regarding the addition of cleavable crosslinkers to modulate the network porosity. In this scenario, the aim of this work is to design, synthesize and characterize hydrogel microparticles, based on the copolymerization between PEG-diacrylate and N,N'-(1,2-dihydroxyethylene)-bisacrylamide, a cleavable crosslinker that simultaneously produces pores and reactive groups for bioprobe 3D bioconjugation. The results show great accessibility of these microparticles to antibodies and their complexes, without affecting their diffusion rate. Furthermore, the presence of a well-defined number of reactive aldehydes, produced by the cleavage reaction, allows modulating biosensor sensitivity through a fine control of the conjugation degree. The antibody-conjugated microparticles can efficiently capture the analyte down to a few picograms. These novel microparticles could be used as a highly sensitive platform for biomacromolecule detection in complex fluids, exploiting the combined effects of PEG's anti-fouling properties, large network porosity and interconnections, and three-dimensional bioconjugation.

Platelet activation by riboflavin and UV light: is it really the other side of the coin?

INTRODUCTION: Nowadays transfusion safety is still put at risk by contamination of pathogens. The Mirasol PRT System blocks the replication of pathogens and white blood cells. Our goal was to quantify the activation of platelets after treatment with the Mirasol device. MATERIALS AND METHODS: From September to December 2013, 131 platelet collections were studied using a simple flow cytometric strategy. RESULTS: There was a significant correlation between the percentage of platelet activated before and after the treatment. CONCLUSION: Our results induced us to think that the activation of platelets after treatment was acceptable.