Translation of the highly promising electrogenerated chemiluminescence (ECL) properties of Ir(III) complexes (with tri-n-propylamine (TPrA) as a co-reactant) into a new generation of ECL labels for ligand binding assays necessitates the introduction of functionality suitable for bioconjugation. Modification of the ligands, however, can affect not only the photophysical and electrochemical properties of the complex, but also the reaction pathways available to generate light. Through a combined theoretical and experimental study, we reveal the limitations of conventional approaches to the design of electrochemiluminophores and introduce a new class of ECL label, [Ir(C^N)₂(pt-TOxT-Sq)]⁺ (where C^N is a range of possible cyclometalating ligands, and pt-TOxT-Sq is a pyridyltriazole ligand with trioxatridecane chain and squarate amide ethyl ester), which outperformed commercial Ir(III) complex labels in two commonly used assay formats. Predicted limits on the redox potentials and emission wavelengths of Ir(III) complexes capable of generating ECL via the dominant pathway applicable in microbead supported ECL assays were experimentally verified by measuring the ECL intensities of the parent luminophores at different applied potentials, and comparing the ECL responses for the corresponding labels under assay conditions. This study provides a framework to tailor ECL labels for specific assay conditions and a fundamental understanding of the ECL pathways that will underpin exploration of new luminophores and co-reactants.

3D printing is established as an alternative microfabrication approach, and while printer resolution limits the direct 3D printing of pore features in the micron/submicron range, the use of nanoporous materials allows for the integration of porous membranes in 3D printed devices. Here, nanoporous membranes were formed by digital light projection (DLP) 3D printing using a polymerization-induced phase separation (PIPS) resin formulation. A functionally integrated device was fabricated using resin exchange following a simple, semi-automated manufacturing process. Printing of porous materials from a PIPS resin formulations based on polyethylene glycol diacrylate 250 as monomer was investigated by varying exposure time, photoinitiator concentration, and porogen content to yield materials with average pore size varying from 30–800 nm. Aiming for printing a size-mobility trap for electrophoretic extraction of deoxyribonucleic acid (DNA), conditions for printing materials with a mean pore size of 346 nm and 30 nm were selected for integration in a fluidic device using a resin exchange approach. Under optimized conditions (12.5 V for 20 min), cell concentrations as low as 10³ cells per mL were detected following amplification of the extract by quantitative polymerase chain reaction (qPCR) at a Cq of 29. The efficacy of the size/mobility trap formed by the two membranes is demonstrated by detecting DNA concentrations equivalent to the input detected in the extract while removing 73% of the protein in the lysate. The DNA extraction yield was not statistically different from that obtained using a spin column, but manual handling and equipment needs were significantly reduced. This study demonstrates that nanoporous membranes with tailored properties can be integrated into fluidic devices using a simple manufacturing process based on resin exchange DLP. The process was used to manufacture a size-mobility trap and applied for the electroextraction and purification of DNA from E. coli lysate with reduced processing time, manual handling, and equipment needs compared with a commercially sourced DNA extraction kit. Combining manufacturability and portability with ease of use, the approach has demonstrated potential for manufacturing and using devices used in point-of-need testing for diagnostic nucleic acid amplification testing.

Testing methodologies to accurately quantify interfacial shear strength (IFSS) are essential in order to understand fiber-matrix adhesion. While testing methods at a microscale (single filament fragmentation test—SFFT) and macroscale (Short Beam Shear—SBS) are wide spread, each have their own shortcomings. The Iosipescu (V-notch) tow test offers a mesoscale bridge between the microscale and macroscale whilst providing simple, accurate results with minimal time investment. However, the lack of investigations exploring testing variables has limited the application of Iosipescu testing to only a handful of studies. This paper assesses the effect of carbon fiber tow size within the Iosipescu tow test for epoxy resin. Tow sizes of 3, 6, and 9 k are eminently suitable, while more caution must be shown when examining 12, and 15 k tows. In this work, tows at 18 and 24 k demonstrated failure modes not derived from interfacial failure, but poor fiber wetting. A catalogue of common fracture geometries is discussed as a function of performance for the benefit of future researchers. Finally, a comparison of commercial (T300), amine (T300-Amine), and ethyl ester (T300-Ester) surface modified carbon fibers was conducted. The outcomes of this study showed that the Iosipescu tow test is inherently less sensitive in distinguishing between similar IFSS but provides a more ‘real world’ image of the carbon fiber-epoxy interface in a composite material.

3D printing of membrane-integrated devices for chemotaxis studies of aquatic animals.