Highly luminescent and multi-sensing aggregates co-assembled from Eu-containing polyoxometalate and an enzyme-responsive surfactant in water

Abstract

Aggregated multilamellar spheres with enhanced luminescence and stimulus-responsiveness were co-assembled from Na9(EuW10O36)·32H2O (EuW10) and myristoylcholine chloride (Myr).

Zwitterionic Surfactant Micelle-Directed Self-Assembly of Eu-Containing Polyoxometalate into Organized Nanobelts with Improved Emission and pH Responsiveness

“…Additionally, as reported in recent investigations on the coassembly of cationic surfactants and EuW 10 nanoclusters in water, only hybrid spheres with weak stabilities were immediately formed through strong electrostatic and hydrophobic forces. 29,31 However, in the situation here, the used zwitterionic surfactant, C 14 DMAO, with excellent surface activity and partial protonation property at the solution pH of about 6.5 formed micelles easily to carry a small amount of positive charges. They acted as primary building blocks to drive the self-assembly of EuW 10 clusters into such novel nanobelts via a delicate synergetic effect of appropriate electrostatic, hydrophobic, and hydrogen-bonding interactions at R of 20 as carefully analyzed above.…”

“…Accompanied by the enhanced luminescence, the obvious turbidity and Tyndall effect for hybrid solution at R of 20 could be observed (see the inset photo of Figure 3a), indicating the formation of large supramolecular aggregates, 31 which resulted in successful shielding of part water molecules around EuW 10 nanoclusters and enhanced the luminescent properties. Figure 3a illustrates the transmittance change curve for hybrid solutions at different R values.…”

“…Clearly, upon the addition of little C 14 DMAO, ζ potential became more negative than that of EuW 10 aqueous solution because of the aggregate formation. 31,39 Then, with more C 14 DMAO adding, ζ potential value increased progressively and then became positive because of the neutralization of EuW 10 negative charges by partially protonated C 14 DMAO. It should be noted that only a part of C 14 DMAO molecules could be protonated now at the solution pH value of about 6.5.…”

“…As shown in Figure S1 for calorimetric heat and corresponding integration curve, upon adding C 14 DMAO into EuW 10 aqueous solution slowly, the obvious exothermic change was noticed and the binding constant was obtained as 4.66 × 10 5 M −1 , suggesting the existence of significant electrostatic interaction between such two components. 8,31 In addition, FT-IR measurement was an efficient method to reveal the structural variation and interaction among C 14 DMAO/EuW 10 hybrid aggregates. Figure 4 illustrates the FT-IR spectra of EuW 10 , C 14 DMAO, and their representative hybrid aggregates in the above two stable turbid regions.…”

Functional Nano-Objects by Electrostatic Self-Assembly: Structure, Switching, and Photocatalysis

“…This can either be achieved by removing the metal and/or the addition of acid and base. Combining pH and chemical responsiveness was also focused on in other studies ( Lin et al, 2015 ; Lei et al, 2019b ).…”