A GSH-responsive Fe3O4/DOX co-loaded PEGylated organosilica-based biodegradable nanosystem was developed for magnetically targeted magnetic resonance imaging and tumor chemotherapy.

In this paper, poly(N-isopropylacrylamide-co-3-aminophenylboronic acid) (P(NIPAM-co-APBA)) copolymer films were successfully electropolymerized on the Au electrode surface. The electroactive probe ferrocene carboxylic acid (FCA) in solution showed reversible thermal-, glucose- and pH-responsive on-off cyclic voltammetric (CV) behaviors at the film electrodes. The comparative experiments demonstrated that the thermo-responsive property of the film electrode was ascribed to the PNIPAM component of the films, whereas the glucose- and pH-sensitive behaviors came from the PAPBA constituent. The reduced form of nicotinamide adenine dinucleotide (NADH) could be electrocatalytically oxidized by FCA at the film electrodes, which would greatly amplify the multi-responsive CV signal difference between the on and off states. On the basis of these results, a binary 4-input/4-output logic circuit was fabricated with temperature, glucose, pH and NADH as inputs and the CV responses at 4 different levels as outputs. Moreover, a ternary CONSENSUS logic circuit was established on the same platform, which was the first report on the combination of ternary logic gate and bioelectrocatalysis without using enzymes. This work provided a novel idea for constructing complicated biocomputing systems by increasing the number of inputs/outputs with multi-sensitive interfaces and by designing new types of multi-valued logic gates on the basis of bioelectrocatalysis.

Triple-responsive films with binary architecture for switchable biosensors were designed on electrodes through the combination of the weak polyelectrolyte {PAH/PAA}n (PAH = poly(allylamine hydrochloride), PAA = poly(acrylic acid)) layer-by-layer assembly and chemically polymerized poly(N,N-diethylacrylamide) (PDEA) hydrogel containing horseradish peroxidase (HRP). The films exhibited reversible pH-, thermo-, and sulfate concentration responsively reversible on-off behaviors toward K3Fe(CN)6 in its cyclic voltammetric (CV) response. Taking thermo-switch as an example, at 25°C, CVs showed a large and well-defined peak pair of Fe(CN)63− and the system was at the on state; while at 40°C, the CV peaks were greatly suppressed and the system was at the off state. The bioactivity of HRP enzyme embedded in the films was well maintained and this film system could be further employed to control and modulate the bioelectrochemical reduction of H2O2 by HRP with K3Fe(CN)6 as the mediator in solution. This triple-triggered bioelectrocatalysis based on the binary interface system could be used as a 3-input AND logic gate and demonstrated the potential perspective for fabricating novel multiple factor-switchable biosensors with immobilized enzymes.

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