Stretchable Sponge-Based Electrochemical Biosensor for Real-Time Sensing of Cells in Three-Dimensional Culture.

For the study of cell biology, real-time information on cell physiological processes will be more accurate and closer to the in vivo condition in a three-dimensional (3D) culture system. Although most reported 3D cell culture scaffolds can better mimic the in vivo dynamic microenvironment, the real-time analysis technique is deficient or lacking. Herein, a stretchable and conductive 3D scaffold is developed to construct an electrochemical biosensor for real-time monitoring of cell release in 3D culture under stimulation of drug stimulant and mechanical force. In our design, the polyurethane sponge (PU) dipped with conductive carbon ink (CC/PU) was used as a conductive scaffold, and gold nanoparticles (nano-Au) were electrodeposited on the CC/PU (nano-Au CC/PU) to improve the electrochemical sensing performance. The prepared nano-Au CC/PU scaffold exhibits a good electrocatalytic ability to H2O2 with a linear range from 20 nM to 43 µM. Due to the great biocompatibility, HeLa cells can be cultured directly on the nano-Au CC/PU and the in situ and real-time tracking of H2O2 secretion from cells was achieved. The results demonstrate that both the drug stimulant and mechanical force can rapidly activate the release of reactive oxygen species. This study indicates that the stretchable 3D sensing scaffold has good potential for cell biology research in an in vivo-like microenvironment and can be extensively used in the fields of tissue engineering, drug screening, and pathological research.

Honeycomb-like nickel oxide-reduced graphene oxide based sensor for the electrochemical tracking of norepinephrine in neuronal cells.

Highly sensitive and specific detection and monitoring of trace norepinephrine (NE) in biological fluids and neuronal cell lines is essential for the investigation of pathogenesis of certain neurological diseases. Herein, we constructed a novel electrochemical sensor for real-time monitoring of NE released by PC12 cells based on glassy carbon electrode (GCE) modified with honeycomb-like nickel oxide (NiO)-reduced graphene oxide (RGO) nanocomposite. The synthesized NiO, RGO and the NiO-RGO nanocomposite were characterized using X-ray diffraction spectrogram (XRD), Raman spectroscopy and scanning electron microscopy (SEM). The porous three-dimensional honeycomb-like structure of NiO and high charge transfer kinetics of RGO endowed the nanocomposite with excellent electrocatalytic activity, large surface area and good conductivity. The developed sensor exhibited superior sensitivity and specificity towards NE in a wide linear range from 20 nM to 14 µM and 14 µM-80 µM, with a low detection limit of 5 nM. The performances of the sensor in terms of excellent biocompatibility and high sensitivity allow it to be successfully employed in the tracking of NE release from PC12 cells under the stimulation of K+, providing an effective strategy for the real-time monitoring of cellular NE.

Stretchable Electrochemical Sensor Based on a Gold Nanowire and Carbon Nanotube Network for Real-Time Tracking Cell-Released H2S.

Hydrogen sulfide (H2S), as the third gas transporter in biological systems, plays a key role in the regulation of biological cells. Real-time detection of local H2S concentration in vivo is an important and challenging task. Herein, we explored a novel and facile strategy to develop a flexible and transparent H2S sensor based on gold nanowire (AuNW) and carbon nanotube (CNT) films embedded in poly(dimethylsiloxane) (PDMS) (AuNWs/CNTs/PDMS). Taking the advantage of the sandwich-like nanostructured network of AuNWs/CNTs, the prepared electrochemical sensing platform exhibited desirable electrocatalytic activity toward H2S oxidation with a wide linear range (5 nM to 24.9 µM) and a low dete ction limit (3 nM). Furthermore, thanks to the good biocompatibility and flexibility of the sensor, HeLa cells can be cultured directly on the electrode, allowing real-time monitoring of H2S released from cells under a stretched state. This work provides a versatile strategy for the construction of stretchable electrochemical sensors, which has potential applications in the study of H2S-related signal mechanotransduction and pathological processes.