Uranyl (UO2(2+)) is a form of uranium in aqueous solution that represents the greatest risk to human health because of its bioavailability. Different sensing techniques have been used with very sensitive detection limits especially the recently reported uranyl-specific DNAzymes systems. However, to the best of our knowledge, few efficient detection methods have been reported for uranyl sensing in seawater. Herein, gold nanoclusters (AuNCs) are employed in an efficient spectroscopic method to detect uranyl ion (UO2(2+)) with a detection limit of 1.86 μM. In the absence of UO2(2+), the BSA-stabilized AuNCs (BSA-AuNCs) showed an intrinsic peroxidase-like activity. In the presence of UO2(2+), this activity can be efficiently restrained. The preliminary quenching mechanism and selectivity of UO2(2+) was also investigated and compared with other ions. This design strategy could be useful in understanding the binding affinity of protein-stabilized AuNCs to UO2(2+) and consequently prompt the recycling of UO2(2+) from seawater.

This research investigates the modification and dispersion and of pristine multiwalled carbon nanotubes (MWCNTs) through a simple solution mixing technique based on noncovalent interactions between poly(phenylene ethynylene)-based conjugated polyelectrolytes functionalized with cationic imidazolium solubilizing groups (PIM-2 and PIM-4) and MWCNTs. Spectroscopic studies demonstrated the ability of PIMs to strongly interact with and efficiently disperse MWCNTs in different solvents, mainly due to π interactions between the PIMs and the MWCNTs. Transmission electron microscopy and atomic force microscopy revealed the coating of the polyelectrolytes on the walls of the nanotubes. Scanning electron microscopy (SEM) studies confirm the homogeneous dispersion of PIM-modified MWCNTs in the poly(methyl methacrylate) (PMMA) matrix. The addition of 1 wt % PIM-modified MWCNTs to the matrix has led to a significant decrease in DC resistivity of the composite (13 orders of magnitude). The increase in electrical conductivity and the improvement in the thermal and mechanical properties of the membranes containing the PIM-modified MWCNTs is ascribed to the formation of MWCNT networks and cross-linking sites that provided channels for the electrons to move in throughout the matrix and reinforced the interface between MWCNTs and PMMA.