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A promising electrochemical sensing platform based on imprinting chitosan (CS) nanocomposites integrating multi-walled carbon nanotubes (MWCNTs)/graphene (GR)/gold nanoparticles (AuNPs)/Nafion was developed for the sensitive and selective detection of Pb2+. The platform was constructed via drop coating and electrodeposition methods and characterized by using cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. Under the optimized conditions, the proposed sensor showed good sensitive determination of Pb2+ in the range of 1.0 × 10−9–5.0 × 10−5 mol L−1 with a detection limit of 2.83 × 10−10 mol L−1. In the presence of interfering metal ions, the fabricated sensor could selectively detect Pb2+. Meanwhile, the imprinted sensor exhibited high repeatability, good reproducibility and stability. The successful detection of Pb2+ in water and milk samples suggested its potential application for monitoring Pb2+ in complex water systems for environmental protection and food safety applications. [ABSTRACT FROM AUTHOR]

Inspired by the polymeric "soft" properties and divisional isolation of tandem processes in natural systems, an artificial reactor with self‐screened catalytic ability was fabricated with a polymeric tri‐layer architecture. The non‐responsive middle layer encapsulated catalytic metal nanoparticles, while the two outer layers consisted of a negatively and a positively thermosensitive imprinted polymer. The inverse responsiveness of the outer layers induced switchable shapes, which led to alterable tandem channeling to the reactive middle layer and, as a result, the divisional admission of different substrates. This way, the reactor led to the formation of self‐screened catalytic ability. The design for this artificial reactor offers promising prospects for struggling tandem catalysts, suggesting opportunities to develop schedulable tandem processes. [ABSTRACT FROM AUTHOR]

A sensitive and selective electrochemical sensor based on ion-imprinted chitosan-graphene nanocomposites (IIP-S) has been developed for the determination of Cr(VI). The ion-imprinted polymers were constructed by one-step electrodeposition. The morphology and structure of IIP-S were characterized by SEM, TEM, XRD, FTIR and EDS, respectively. Meanwhile, the electrochemical behavior of IIP-S was investigated using CV, EIS and DPV. The linear range of IIP-S was from 1.0 × 10 −9 to 1.0 × 10 −5  mol/L, with the low detection limit of 6.4 × 10 −10  mol/L (S/N = 3). The sensor exhibited high selectivity for the determination of Cr(VI) in the presence of Zn(II), Co(II), Cu(II), Ni(II), Mn(II), MnO 4− , C 2 O 4 2− , S 2 O 6 2− and MoO 4 2− ions. The IIP-S also provided excellent stability and good repeatability that the sensitivity remained 85% after 9 cycles of rebinding-removal, while the sensitivity retained 87% of its initial response storing at 4 °C for 17 days. Moreover, it was successfully applied to the detection of Cr(VI) ions in tap water and river water. [ABSTRACT FROM AUTHOR]

The realization of selective/nonselective-switchable catalytic ability remains a significant challenge in controlled catalytic processes. We herein report an originally-designed imprinted polymer nanoreactor capable of meeting this challenge. This nanoreactor was composed of Ag nanoparticles and a unique holothurian-inspired imprinted polymer carrier that contained mobile molecular chains. These mobile molecular chains, by motioning and lying motionless, enabled the imprinted carrier to function in an 'online/offline'-shiftable paradigm, causing switchable access to the encapsulated metal nanoparticles. This nanoreactor showed selective catalytic ability at relatively low temperatures due to the 'frozen' molecular chains, which allowed for substrate-selective access to the encapsulated metal nanoparticles (i.e., imprinted carrier's 'online' status). In contrast, this nanoreactor provided non-selective catalysis at relatively high temperatures in response to the increased mobility of these molecular chains, which resulted in dismantling the selective access (i.e., imprinted carrier's 'offline' status). Unlike reported imprinted polymer nanoreactors which simply provide selective catalysis, this novel nanoreactor allows selective/nonselective-switchable catalysis in virtue of the bio-inspired design. This study opens up opportunities to modulate catalytic selectivity for controlled chemical processes. [ABSTRACT FROM AUTHOR]

This study is aimed at addressing the present challenges of self-controlled processes in tandem catalysis. Inspired by the opening and closing switchable behaviors of stomata in plant leaves arose by temperature, the objective is met by originally developing a "smart" tandem catalyst capable of crossing-response properties. The catalyst consisted of two unique functional layers where each may self-govern one coupled process. The first layer was fabricated with a negatively-thermosensitive imprinted polymer and encapsulated metal nanoparticles (PDEA- co -PAM/Ag) which were responsible for a catalytic reduction process. The second layer was made of a positively-thermosensitive polymer (PVI- co -PAMPS) with acidic groups, which were capable of a catalytic hydrolysis process. At low temperatures, this catalyst would conduct only catalytic reduction because of the open channel in the first layer. In middle temperatures, the catalyst would run the tandem processes from catalytic reduction to hydrolysis because of the open channels in both the two layers. At higher temperatures, the catalyst only catalyzed hydrolysis because of the closed channel in the first layer. In this way, the smart bi-layer catalyst achieved the single/tandem/single catalysis featured with a dual temperature-responsive switch. The novel protocol not only provides a new solution to complicated catalytic processes but also inspires the further application of smart polymers in a broader spectrum of areas. The switchable mechanism of the polymer reactor. [Display omitted] • Thermo-sensitive tandem catalyst is able to adapt to the changing environment. • A "smart" tandem catalyst is capable of crossing-response properties. • The catalyst is able to conduct the single/tandem/single reactions in different temperatures. • New catalyst shares a promising prospect to the development of one-pot catalytic processes in applications. [ABSTRACT FROM AUTHOR]