Multi-walled carbon nanotubes-metal-organic framework nanocomposite based sensor for the monitoring of multiple monoamine neurotransmitters in living cells.

The levels of monoamine neurotransmitters (MNTs) including dopamine (DA), adrenaline (Adr), norepinephrine (NE) and 5-hydroxytryptamine (5-HT) in cells are useful indicators to explore the pathogenesis of MNTs-related diseases such as Alzheimer's disease, Parkinson's disease and depression. Herein, we constructed a novel electrochemical sensing platform based on multi-walled carbon nanotubes (MWCNTs)-amine functionalized Zr (IV) metal-organic framework (UIO-66-NH2) nanocomposite for the detection of multiple MNTs including DA, Adr, NE and 5-HT. The synergistic effect between MWCNTs and UIO-66-NH2 endowed the nanocomposite with high specific surface area, low interface impedance and superior electrocatalytic activity, which effectively enhance the electrochemical performance of the sensor. The MWCNTs-UIO-66-NH2 nanocomposite-based sensor exhibited satisfied sensitivity for the quantitative measurement of DA, Adr, NE and 5-HT, as well as low detection limit. The outstanding biocompatibility of the constructed sensor permitted it to be successfully implemented for the real-time monitoring of DA released by PC12 and C6 cells, providing a promising strategy for clinical diagnosis of MNTs-related disorders and diseases.

Flexible and multi-functional three-dimensional scaffold based on enokitake-like Au nanowires for real-time monitoring of endothelial mechanotransduction.

Endothelial cells are sensitive to mechanical force and can convert it into biochemical signals to trigger mechano-chemo-transduction. Although conventional techniques have been used to investigate the subsequent modifications of cellular expression after mechanical stimulation, the in situ and real-time acquiring the transient biochemical information during mechanotransduction process remains an enormous challenge. In this work, we develop a flexible and multi-functional three-dimensional conductive scaffold that integrates cell growth, mechanical stimulation, and electrochemical sensing by in situ growth of enokitake-like Au nanowires on a three-dimensional porous polydimethylsiloxane substrate. The conductive scaffold possesses stable and desirable electrochemical sensing performance toward nitric oxide under mechanical deformation. The prepared e-AuNWs/CC/PDMS scaffold exhibits a good electrocatalytic ability to NO with a linear range from 2.5 nM to 13.95 µM and a detection limit of 8 nM. Owing to the excellent cellular compatibility, endothelial cells can be cultured directly on the scaffold and the real-time inducing and recording of nitric oxide secretion under physiological and pathological conditions were achieved. This work renders a reliable sensing platform for real-time monitoring cytomechanical signaling during endothelial mechanotransduction and is expected to promote other related biological investigations based on three-dimensional cell culture.