Search

Metal nanoparticle (NP) incorporated conductive polymer films are attractive for their mechanical stability for biomedical applications and as heterogeneous electrocatalysis materials. Novel approaches to generate these materials with tunable properties are still being sought. Herein, the interface between two immiscible electrolyte solutions (ITIES) has been employed as a molecularly sharp and reproducible platform for simultaneous Au NP and poly(9-vinylcarbazole) generation. Three interfaces have been compared, including between water|1,2-dichloroethane (w|DCE), water|α,α,α-trifluorotoluene (w|TFT), and water|ionic liquid (w|IL). In this case the IL was P8888TB (tetraoctylphosphonium tetrakis(pentafluorophenyl)borate). 9-Vinylcarbazole (VC) can polymerize via two routes, either propagating through the vinyl substituent or the aryl rings. The former gives rise to a white semiconducting polymer with a wide bandgap, while the latter produces a green, conducting polymer. External potential control through voltammetric cycling was found to generate the film more rapidly favoring heterogeneous electron transfer with formation of the green poly(VC) variant at the ITIES. This was a free-standing film that could be easily removed from the interface. In the absence of external control, white polymer crystals formed within the oil phase spontaneously likely via AuCl4–w → o transfer followed by a homogeneous electron transfer reaction mechanism. Scanning electrochemical microscopy probe approach curve experiments were used to quantify the electroactivity of the film and are complemented by direct conductivity measurements.

Opportunistic pathogenic bacteria, such as Pseudomonas aeruginosa, pose a serious risk to patients suffering from a compromised immune system and those patients with cystic fibrosis. Confirming their presence often requires culturing the bacteria, which can take days. Herein is proposed a rapid electrochemical detection method based on P. aeruginosa-generated small molecules employed for chemical communication, referred to as quorum sensing (QS) molecules, within the biofilm formed by the bacteria; specifically, 4-hydroxy-2-heptylquinoline (HHQ) and 2-heptyl-3,4-dihydroxyquinoline (pseudomonas quinolone signal, PQS). This method does not depend on the redox activity of the QS molecules. Instead, as a proof-of-concept, electrochemical monitoring was achieved through aqueous alkali metal ion and proton interfacial complexation with organic-solubilized HHQ and PQS at an interface between two immiscible electrolytic solutions, specifically, between water and 1,2-dichloroethane. The proton/HHQ and proton/PQS binding stoichiometries were discovered to be 1:3 and 1:2, respectively, which is likely due to the relatively high concentrations of QS molecules employed. Owing to the biphasic nature of the methodology, experimental complications due to the poor solubility of the hydrophobic QS molecules in aqueous media were avoided.