Bio-inspired porous antenna-like nanocube/nanowire heterostructure as ultra-sensitive cellular interfaces

In this study, an unconventional antenna-like heterostructure comprised of arrays of nanoporous Prussian blue (PB) nanocube heads/TiO₂ nanowire (NW) arms (PB-TiO₂) is developed for efficient three-dimensional interfacial sensing of small molecules and cellular activities. Inspired by insect tentacles, which are comprised of both target recognition and signal transduction units, one-dimensional TiO₂ NW arrays are grown, followed by selective growth of nanoporous PB nanocubes on the tips of the NW arrays. Due to their high selectivity and bioaffinity toward cells, long biostability under a cell culture adhesion condition (up to 108 h) is obtained, and with its inherent bio-mimetic enzymatic activity, the obtained nanoporous PB nanocubes (head segment) serve as robust substrates for site-selective cell adhesion and culture, which allows for sensitive detection of H ₂O₂. Simultaneously, the single-crystalline TiO ₂ NWs (arm segment) provide efficient charge transport for electrode substrates. Compared with PB-functionalized planar electrochemical interfaces, the PB-TiO₂ antenna NW biointerfaces exhibit a substantial enhancement in electrocatalytic activity and sensitivity for H₂O ₂, which includes a low detection limit (~20 nM), broad detection range (10^-8 to 10^-5 M), short response time (~5 s) and long-term biocatalytic activity (up to 6 months). The direct cultivation of HeLa cells is demonstrated on the PB-TiO₂ antenna NW arrays, which are capable of sensitive electrochemical recording of cellular activity in real time, where the results suggest the uniqueness of the biomimic PB-TiO ₂ antenna NWs for efficient cellular interfacing and molecular recognition.