Enzyme and AIEgens Modulated Solid‐State Nanochannels: In Situ and Noninvasive Monitoring of H₂O₂ Released from Living Cells

Abstract

Solid‐state nanochannels have revealed great abilities in the sensing of ions, small biomolecules, and biological macromolecules. However, the current platform requires pretreatment of real samples to extract targets, which may induce false signals due to complicated collection and addition processes. Although nanopore electrodes or nanopipettes have been successfully utilized in the detection of intracellular redox‐active species without sample preparation processes, the insertion of nanoprobes to living cells is inevitable. Here, a strategy is reported to monitor H2O2 released from living cells based on functionalized solid‐state nanochannels without an insertion procedure. In this strategy, aggregation‐induced emission luminogens (AIEgens) with enzyme‐responsive linkage properties are combined in solid‐state nanochannels. When H2O2 released from cervical cancer cells (HeLa), Tyr‐containing AIEgens (TT) will form horseradish peroxidase‐modulated (HRP‐modulated) linkages in the nanochannels. The formation of linkages can result in the effective blockade of nanochannels, hence via transmembrane ionic current. Owing to the aggregation of linkage products, a fluorescence signal can be observed. By using these dual‐signal‐output nanochannels, in situ and noninvasive detection of H2O2 is able to be achieved. Together with molecular dynamic (MD) simulations results, solid surface zeta potential and contact angle experiments, it is concluded that the blockage of nanochannels is the dominate factor for ionic currents as well as fluorescence change.

Nanoconfinement Effect for Signal Amplification in Electrochemical Analysis and Sensing

“…Reproduced with permission. [ 61 ] Copyright 2019, WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim. C) Assembly and disassembly of nHCR nanostructures inside nanochannels by employing an nHCR nanostructure as a molecular gate.…”

“…[60] Recently, Lou et al combined aggregation-induced luminescence with electrochemistry to monitor H 2 O 2 in a dual-signal output mode (Figure 4A). [61] By modifying nanochannels with capture probes, the linkages of the polymer were triggered in nanochannels with the aid of H 2 O 2 and HRP, resulting in effective blockage of the nanochannels. To investigate how the growing structures influence the blocking process, molecular dynamics (MD) simulations were performed in free space and confined nanochannels.…”

Bioinspired Solid‐State Nanochannel Sensors: From Ionic Current Signals, Current, and Fluorescence Dual Signals to Faraday Current Signals

“…Another example using AIE is realization of in situ and noninvasive monitoring of H 2 O 2 released from living cells (Figure 8b (i)). [28] As shown in Figure 8b (ii), H 2 O 2 irritant would trigger efficiently obstructing of the nanochannels and thus decrement of transmembrane ionic current (on-tooff) as well as AIE effect and thus increment of fluorescence intensity (off-to-on), synchronously. Such result is attributable to the formation of tyrosine-containing AIEgens (TT) oligomer upon the participation of H 2 O 2 and the catalysis of horseradish peroxidase and covalently immobilization onto the surface of functionalized channels (Figure 8b (iii)).…”

“…Schematic representation (iii) of the phenolic hydroxyl groups functionalized nanochannels for H 2 O 2 analysis using HRP and TT assistant oligomerization reaction mechanism. Reproduced with permission [28]. Copyright 2019, Wiley-VCH.…”

Rational design of a self-assembled surfactant film in nanopipettes: combined fluorescence and electrochemical sensing

“…The introduction of a fluorophore made dual-signal sensing possible, which provided an additional signal supplement for nanopipette electrochemistry. Compared with the previous dual-signal sensing methods, 17–19 we provided a label-free functionalization method to build a nanopipette dual-signal sensing platform, which was successfully used for the assessment of Arg metabolism. The results demonstrated great promise for the self-assembled surfactant film in designing sensitive and selective nanopipette sensors.…”