Highly Sensitive and Omnidirectionally Stretchable Bioelectrode Arrays for In Vivo Neural Interfacing.

Flexible electrode array, a new-generation neural microelectrode, is a crucial tool for information exchange between living tissues and external electronics. Till date, advances in flexible neural microelectrodes are limited because of their high impedance and poor mechanical consistency at tissue interfaces. Herein, a highly sensitive and omnidirectionally stretchable polymeric electrode array (PEA) is introduced. Micropyramid-nanowire composite structures are constructed to increase the effective surface area of PEA, achieving an exponential reduction in impedance compared with gold (Au) and flat polypyrrole electrodes. Moreover, for the first time, a suspended umbrella structure to enable PEA with omnidirectional stretchability of up to ≈20% is designed. The PEA can withstand 1000 cycles of mechanical loads without decrease in performance. As a proof of concept, PEA is conformally attached to a rat heart and tibialis anterior muscle, and electrophysiological signals (electrocardiogram and electromyogram) of the rat are successfully recorded. This strategy provides a new perspective toward highly sensitive and omnidirectionally stretchable PEA that can facilitate the practical application of neural electrodes.

A novel mitochondrial-targeted two-photon fluorescent probe for ultrafast monitoring of SO2 derivatives and its applications.

SO2 derivatives maintain a certain balance and play an important role in many metabolic processes. However, excessive ingestion of them can lead to serious complications of various diseases. Therefore, a rapid and precision detection of SO2 derivatives with high selectivity and sensitivity would be an advance for their bio-analytic studies. Accordingly, a novel deep red and two-photon fluorescent SO2 derivatives probe (DRQ) was developed here for the first time. The probe showed fast ratio response rate (within 5 s), excellent sensitivity (the detection limit is 103 nM for red channel and 17 nM for green channel), and outstanding selectivity toward SO2 derivatives in 10 mM PBS buffer. Moreover, the ratiometric probe DRQ displays a 99 nm blue-shift in emission upon addition of SO2 derivatives. Intriguingly, the probe can be made into test papers for real-time monitoring of SO2 derivatives. Moreover, it can be also applied for visual ratio imaging of SO2 derivatives in cellular mitochondria and zebrafish under two-photon absorption (green channel) and one-photon absorption (red channel).