Real-time monitoring of intracellular biochemical response in locally stretched single cell by a nanosensor.

Mechanotransduction is the essential process that cells convert mechanical force into biochemical responses, and electrochemical sensor stands out from existing techniques by providing quantitative and real-time information about the biochemical signals during cellular mechanotransduction. However, the intracellular biochemical response evoked by mechanical force has been poorly monitored. In this paper, we report a method to apply local stretch on single cell and simultaneously monitor the ensuing intracellular biochemical signals. Specifically, a ferromagnetic micropipette was fabricated to locally stretch a single cell labeled with Fe3O4 nanoparticles under the external magnetic field, and the SiC@Pt nanowire electrode (SiC@Pt NWE) was inserted into the cell to monitor the intracellular hydrogen peroxide (H2O2) production induced by the local stretch. As a proof of concept, this work quantitatively investigated the elevated amount of H2O2 levels in single endothelial cell under different stretching amplitudes. This work puts forward a new research modality to manipulate and monitor the mechanotransduction at the single-cell level.

Mechanical Strain Induces and Increases Vesicular Release Monitored by Microfabricated Stretchable Electrodes.

Exocytosis involving the fusion of intracellular vesicles with cell membrane, is thought to be modulated by the mechanical cues in the microenvironment. Single-cell electrochemistry can offer unique information about the quantification and kinetics of exocytotic events; however, the effects of mechanical force on vesicular release have been poorly explored. Herein, we developed a stretchable microelectrode with excellent electrochemical stability under mechanical deformation by microfabrication of functionalized poly(3,4-ethylenedioxythiophene) conductive ink, which achieved real-time quantitation of strain-induced vesicular exocytosis from a single cell for the first time. We found that mechanical strain could cause calcium influx via the activation of Piezo1 channels in chromaffin cell, initiating the vesicular exocytosis process. Interestingly, mechanical strain increases the amount of catecholamines released by accelerating the opening and prolonging the closing of fusion pore during exocytosis. This work is expected to provide revealing insights into the regulatory effects of mechanical stimuli on vesicular exocytosis.

Real-Time Quantification of Nanoplastics-Induced Oxidative Stress in Stretching Alveolar Cells.

Nanoplastics from air pollutants can be directly inhaled into the alveoli in the lungs and further enter blood circulation, and numerous studies have revealed the close relation between internalized nanoplastics with many physiological disorders via intracellular oxidative stress. However, the dynamic process of nanoplastics-induced oxidative stress in lung cells under breath-mimicked conditions is still unclear, due to the lack of methods that can reproduce the mechanical stretching of the alveolar and simultaneously monitor the oxidative stress response. Here, we describe a biomimetic platform by culturing alveoli epithelial cells on a stretchable electrochemical sensor and integrating them into a microfluidic device. This allows reproducing the respiration of alveoli by cyclic stretching of the alveoli epithelial cells and monitoring the nanoplastics-induced oxidative stress by the built-in sensor. By this device, we prove that cyclic stretches can greatly enhance the cellular uptake of nanoplastics with the dependencies of strain amplitude. Importantly, oxidative stress evoked by internalized nanoplastics can be quantitatively monitored in real time. This work will promote the deep understanding about the cytotoxicity of inhaled nanoplastics in the pulmonary mechanical microenvironment.

Flexible and Stretchable Electrochemical Sensors for Biological Monitoring.

The rise of flexible and stretchable electronics has revolutionized biosensor techniques for probing biological systems. Particularly, flexible and stretchable electrochemical sensors (FSECSs) enable the in situ quantification of numerous biochemical molecules in different biological entities owing to their exceptional sensitivity, fast response, and easy miniaturization. Over the past decade, the fabrication and application of FSECSs have significantly progressed. This review highlights key developments in electrode fabrication and FSECSs functionalization. It delves into the electrochemical sensing of various biomarkers, including metabolites, electrolytes, signaling molecules, and neurotransmitters from biological systems, encompassing the outer epidermis, tissues/organs in vitro and in vivo, and living cells. Finally, considering electrode preparation and biological applications, current challenges and future opportunities for FSECSs are discussed.

Nanofiber-based Stretchable Electrodes for Oriented Culture and Mechanotransduction Monitoring of Smooth Muscle Cells.

Vascular smooth muscle cells (SMCs) are circumferentially oriented perpendicular to the blood vessel and maintain the contractile phenotype in physiological conditions. They can sense the mechanical forces of blood vessels expanding and contracting and convert them into biochemical signals to regulate vascular homeostasis. However, the real-time monitoring of mechanically evoked biochemical response while maintaining SMC oriented growth remains an important challenge. Herein, we developed a stretchable electrochemical sensor by electrospinning aligned and elastic polyurethane (PU) nanofibers on the surface of PDMS film and further modification of conductive polymer PEDOT:PSS-LiTFSI-CoPc (PPLC) on the nanofibers (denoted as PPLC/PU/PDMS). The aligned nanofibers on the electrode surface could guide the oriented growth of SMCs and maintain the contractile phenotype, and the modification of PPLC endowed the electrode with good electrochemical sensing performance and stability under mechanical deformation. By culturing cells on the electrode surface, the oriented growth of SMCs and real-time monitoring of stretch-induced H2O2 release were achieved. On this basis, the changes of H2O2 level released by SMCs under the pathology (hypertension) and intervention of natural product resveratrol were quantitatively monitored, which will be helpful to further understand the occurrence and development of vascular-related diseases and the mechanisms of pharmaceutical intervention.

Adjuvant treatment for patients with incidentally resected limited disease small cell lung cancer-a retrospective study.

Background: With the exception of very early-stage small cell lung cancer (SCLC), surgery is not typically recommended for this disease; however, incidental resection still occurs. After incidental resection, adjuvant salvage therapy is widely offered, but the evidence supporting its use is limited. This study aimed to explore proper adjuvant therapy for these incidentally resected SCLC cases. Methods: Patients incidentally diagnosed with SCLC after surgery at the Shanghai Pulmonary Hospital in China from January 2005 to December 2014 were included in this study. The primary outcome was overall survival. Patients were classified into different group according to the type of adjuvant therapy they received and stratified by their pathological lymph node status. Patients' survival was analyzed using a Kaplan-Meier analysis and Cox regression analysis. Results: A total of 161 patients were included in this study. Overall 5-year survival rate was 36.5%. For pathological N0 (pN0) cases (n=70), multivariable analysis revealed that adjuvant chemotherapy (ad-chemo) was associated with reduced risk of death [hazard ratio (HR): 0.373; 95% confidence interval (CI): 0.141-0.985, P=0.047] compared to omission of adjuvant therapy. For pathological N1 or N2 (pN1/2) cases (n=91), taking no adjuvant therapy cases as a reference, the multivariable analysis showed that ad-chemo was not associated with a lower risk of death (HR: 0.869; 95% CI: 0.459-1.645, P=0.666), while adjuvant chemo-radiotherapy (ad-CRT) was associated with a lower risk of death (HR: 0.279; 95% CI: 0.102-0.761, P=0.013). Conclusions: Patients who incidentally receive surgical resection and are diagnosed with limited disease SCLC after resection should be offered adjuvant therapy as a salvage treatment. For incidentally resected pN0 cases, ad-chemo should be considered and for pN1/2 cases, ad-CRT should be received.