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.

Preparation of nanostructured PDMS film as flexible immunosensor for cortisol analysis in human sweat.

This work proposed a novel and flexible immunosensor for highly selective and sensitive determination of cortisol in sweat. The flexible electrode was developed by transferring multi-walled carbon nanotubes (MWCNTs) film on polydimethylsiloxane (PDMS) substrate and subsequent electrochemical deposition of Au nanoparticles (AuNPs) on the MWCNTs surface. The obtained AuNPs/MWCNTs/PDMS electrode was then covalently immobilized with anti-cortisol monoclonal antibody (Anti-Cmab) and blocked with BSA. Scanning electron microscope confirmed that MWCNTs have been firmly combined with PDMS and AuNPs distributed uniformly on the surface of MWCNTs. The PDMS-based sensor possesses a good mechanical stability against stretching, bending and twisting, displaying stable electrochemical performance under deformation. After optimizing the analytical parameters, the developed immunosensor allowed a facile quantification of cortisol in the range of 1 fg/mL-1 µg/mL with a detection limit of 0.3 fg/mL. The cortisol immunosensor was further used to evaluate cortisol levels in human sweat, and the results corresponded closely with commercially available chemiluminescence immunoassay (CLIA) method. Results indicated that the new cortisol immunosensor could provide an effective tool for the noninvasive, point of care measurement of sweat cortisol levels and is promise to be a wearable biosensor for the healthy monitoring.