Water-dispersible superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized by thermal decomposition of iron(III) acetylacetonate in the presence of triethylene glycol (TREG). The resulting TREG-coated SPIONs were not stable, undergoing agglomeration and loss of the TREG coating under prolonged storage at 37 °C or in the presence of increased saline concentrations. To avoid these problems, stable colloidal TREG-coated SPIONs were obtained by two different procedures: (i) dimercaptosuccinic acid (DMSA) ligand-exchange reactions to obtain DMSA-coated SPIONs and (ii) chemical modification of the TREG coating. Both procedures, but especially the DMSA exchange, increased the stability of the SPION suspension. Finally, the functionality of both types of particles for biological applications was demonstrated by conjugating a model antibody to the end carboxyl groups of the SPIONs and testing the immunoreactivity of the final antibody–particle conjugates by an enzyme-linked immunosorbent assay (ELISA).

This work demonstrates the design and fabrication of an all cyclo-olefin polymer based microfluidic device capable of capturing magnetic beads and performing electrochemical detection in a series of gold electrodes. The size of chip is of a microscope slide and features six independent measuring cells for multianalyte detection purposes. The aim of this work is to show that rapid prototyping techniques can be instrumental in the development of novel bioassays, particularly in clinical diagnosis applications. We show the successful determination of troponin-T, a cardiac disease marker, in the clinically relevant range of 0.05-1.0 ng/mL. This methodology achieves a detection limit of 0.017 ng/mL in PBS solutions, and is capable of detecting less than 1 ng/mL in a 1:50 human serum dilution.

Brain natriuretic peptides (BNPs) are well established cardiovascular disease (CVD) biomarkers, which are released from the heart after ventricular wall stress. Particularly, the N-terminal proBNP (NT-proBNP) is a 76 aa...