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 H2O2. Simultaneously, the single-crystalline TiO2 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 H2O2, 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-TiO2 antenna NWs for efficient cellular interfacing and molecular recognition. Insect tentacles have inspired researchers to make the first antenna-like nanosensor for the ultrasensitive detection of hydrogen peroxide at cell surfaces, and the creative concept of sensing and recognition could be adapted to detect other important biomolecules. Professor Dongyuan Zhao, Gengfeng Zheng and colleagues at Fudan University in China and Monash University in Australia made antenna-like structures from nanocubes of Prussian blue pigment attached to a titanium dioxide arm. The Prussian blue molecules catalyze electron transfer reactions that convert hydrogen peroxide into oxygen and water and the titanium dioxide arm carries the resulting electric current to a substrate surface where it is amplified and detected. The high surface area and porosity of the nanocubes allows much greater sensitivity and selectivity than traditional sensors. The antenna-like nanosensor also has remarkable affinity towards living cells and standout stability in cell cultures. Unconventional nanoporous antenna-like heterostructure arrays, inspired by insect tentacles, are developed for efficient interfacial sensing of biomolecules and cellular activities. The obtained nanoporous cubes (head segments) serve as a robust substrate for site-selective cell adhesion and culture, allowing for sensitive detection of biomolecules. Meanwhile, the single-crystalline nanowires (arm segment) provide efficient charge transport toward the electrode substrate. The inspired hetero-biointerfaces exhibit substantial enhanced electrocatalytic activity and sensitivity for biomolecules.