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Nanoscale control over pore surface properties is a challenging objective for nanopore research and could enable advanced bioanalytical applications, along with enhanced precision and accuracy of existing measurement processes. This work reports a one-pot strategy for the functionalization of thermoplastic polyurethane (TPU) tunable nanopores with polymer brushes. These elastomeric pores are used for tunable resistive pulse sensing (TRPS), which can detect and analyze a broad range of microparticle and nanoparticle species in aqueous electrolytes. Grafting is achieved using the recently developed Graf tfast method, via the chemical reduction of diazonium salts. The study focuses on Graf tfast of negatively charged poly(acrylic acid) (PAA) brushes. The method is further exemplified through the grafting of neutral brushes with a view to utilizing their possible antifouling properties: zwitterionic poly(sulfobetaine), 2hydroxyethyl methacrylate, and poly(ethylene glycol) methyl ethermethacrylate. The successful TPU functionalization was characterized using Fourier transform infrared spectroscopy, contact angle measurements, and X-ray photoelectron spectroscopy. For PAA-grafted pores, the TRPS configuration was used for studies of ionic current rectification, streaming potential, and resistive pulse durations for 500-nm-diameter carboxylated polystyrene spheres. Results were consistent with increased negative surface charge on the pore walls, confirming successful pore functionalization.

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Abstract:The multiresponsive behavior of functionalized water-soluble conjugated polymers (CPs) is presented with potential applications for sensors. In this study, we investigated the aqueous solubility behavior of water-soluble CPs with high photoluminescence and with a particular focus on their pH and temperature responsiveness. For this purpose, two poly(phenylene vinylene)s (PPVs)-namely 2,5-substituted PPVs bearing both carboxylic acid and methoxyoligoethylene glycol units-were investigated, with different amount of carboxylic acid units. Changes in the pH and temperature of polymer solutions led to a response in the fluorescence intensity in a pH range from 3 to 10 and for temperatures ranging from 10 to 85 • C. Additionally, it is demonstrated that the polymer with the largest number of carboxylic acid groups displays upper critical solution temperature (UCST)-like thermoresponsive behavior in the presence of a divalent ion like Ca 2+ . The sensing capability of these water-soluble PPVs could be utilized to design smart materials with multiresponsive behavior in biomedicine and soft materials.