Light-induced Delivery of Charged Species using Ion-selective Core-Shell Nanoparticles.

Controlled release systems have gained considerable attention owing to their potential to deliver molecules, including ions and drugs, in a customized manner. We present a light-induced ion-transfer platform consisting of a dispersion of nanoparticles (NPs, ~300 nm) with the conductive polymer poly(3-octylthiophene-2,5-diyl) (POT) in the core and a potassium (K+)-selective membrane in the shell. Owing to the photoactive nature of POT, POT NPs can be used for a dual purpose: as a host for positively charged species and as an actuator to trigger the subsequent release. POT0 and doped POT+ coexist in the core, allowing K+ encapsulation in the shell. As POT0 is photo-oxidized to POT+, K+ is released to the (aqueous) dispersion phase to preserve the neutrality of the NPs. This process is reversible and can be simultaneously assessed using the native fluorescence of POT0 and via potentiometric measurements. The NP structure and its mechanism of action were thoroughly studied with a series of control experiments and complementary techniques. Understanding the NP and its surrounding interactions will pave the way for other nanostructured systems, facilitating sophisticated applications. The delivery of ionic drugs and interference/pollutant catching for advanced sensing/restoration will be considered in future research.

Chalcogenides-based Tubular Micromotors in Fluorescent Assays.

WS2/Pt and MoS2/Pt bubble propelled micromotors are used as "on-the-fly" sensing platforms in bioassays, using a highly selective affinity peptide probe for "OFF-ON" detection of Escherichia coli as a model endotoxin. The different outer micromotor surface characteristics play an important role in the sensing performance. The relatively high outer surface of WS2/Pt micromotors results in a 3.5-fold increase in sensitivity compared to MoS2/Pt micromotors due to enhanced peptide probe loading and release. The peptide-modified WS2 micromotors are used as a low-cost and high-throughput approach for the determination of E. coli endotoxin after only 60 s, with a limit of detection of 1.9 ng mL-1 and high selectivity. The method has been validated using spiked samples (tap water, blood serum, and saliva) and bacteria media (blank broth, Staphylococcus aureus, and E. coli). The concept can be extended to the analysis of other (bio)-analytes and easily incorporated into portable instrumentation, holding great promise in a myriad of clinical, environmental, or food-safety applications.