Libo Shi

Ultrasensitive detection of superoxide anion released from living cells using a porous Pt-Pd decorated enzymatic sensor.

Considering the critical roles of superoxide anion (O2(∙-)) in pathological conditions, it is of great urgency to establish a reliable and durable approach for real-time determination of O2(∙-). In this study, we propose a porous Pt-Pd decorated superoxide dismutase (SOD) sensor for qualitative and quantitative detection O2(∙-). The developed biosensor exhibits a fast, selective and linear amperometric response upon O2(∙-) in the concentration scope of 16 to 1,536 μM (R(2)=0.9941), with a detection limit of 0.13 μM (S/N=3) and a low Michaelis-Menten constant of 1.37 μM which indicating a high enzymatic activity and affinity to O2(∙-). Inspiringly, the proposed sensor possesses an ultrahigh sensitivity of 1270 μA mM(-1)cm(-2). In addition, SOD/porous Pt-Pd sensor exhibits excellent anti-interference property, reproducibility and long-term storage stability. Beyond our expectation, the trace level of O2(∙-) released from living cells has also been successfully captured. These satisfactory results are mainly ascribed to (1) the porous interface with larger surface area and more active sites to provide a biocompatible environment for SOD (2) the specific biocatalysis of SOD towards O2(∙-) and (3) porous Pt-Pd nanomaterials fastening the electron transfer. The superior electrochemical performance makes SOD/porous Pt-Pd sensor a promising candidate for monitoring the dynamic changes of O2(∙-)in vivo.

Advanced strategies for improving the analytical performance of Pt-based nonenzymatic electrochemical glucose sensors: a minireview

Enormous demands for blood sugar management, food and pharmaceutical quality control, bioprocess monitoring, and environmental pollution inspection have encouraged the fabrication of high-performance sensing platforms for the detection of glucose in various matrices. In comparison with traditional enzyme-based analytical devices, nonenzymatic electrochemical glucose sensors have attracted special interest and the attention of analysts in the past decade due to their unique advantages; however, the underlying drawbacks of detection performance still seriously restrict their commercial development and large-scale application. This minireview clarifies the intrinsic bottlenecks of glucose amperometric analysis on Pt-based enzymeless interfaces, and emphasis is placed on discussing the advanced strategies utilized to enhance the analytical properties of Pt-based enzyme-free electrochemical glucose sensors.

Anneal-shrinked Cu2O dendrites grown on porous Cu foam as a robust interface for high-performance nonenzymatic glucose sensing

Enzyme-free electrochemical detection of glucose in alkaline media with favorable properties has been acquired by fabricating a robust and large-surface sensing platform, which is composed of anneal-shrinked Cu2O dendrites grown on porous Cu foam. On the one hand, the good compatibility of electrodeposited Cu2O architectures and Cu foam substrate, together with a post-deposition anneal at 200°C, offers a mechanically stable interface for glucose determination. On the other hand, the macropores of Cu foam that is decorated with unique Cu2O dendrites provide large active surface for electrocatalytic reaction and mass transport. As a result, selective sensing of glucose in the linear concentration range of 0.001-1.4mM was achieved on the fabricated sensor, with a sensitivity of as high as 5.04mAcm-2mM-1 and a detection limit of 0.13μM. Desired long-term performance stability was obtained, partially due to the strong adhesion of Cu2O microstructures to the Cu foam support after annealing. Practical monitoring of glucose in serum samples was also demonstrated on the proposed sensor.

A facile way to fabricate manganese phosphate self-assembled carbon networks as efficient electrochemical catalysts for real-time monitoring of superoxide anions released from HepG2 cells

Quantification of superoxide anions (O2•-) is significant in the monitoring of many serious diseases and the design of enzyme-mimic catalysts plays the main role in the development of non-enzymatic O2•- sensors. Herein, we proposed a facile self-assembly process to synthesize manganese phosphate modified carbon networks using three kinds of widely-used carbon materials (MWCNTs, NGS and GO) as pillar connectors. Characterizations demonstrate that manganese phosphate is widely dispersed inside and on the surface of carbon networks without visible morphology. Meanwhile, all three kinds of synthesized catalysts were successfully immobilized on the screen-printed carbon electrodes to evaluate the electrochemical performance of fabricated sensors. The results indicate that sensors based on Mnx(PO4)y modified MWCNTs exhibit high sensitivity with an extremely low detection limit of 0.127μM (S/N = 3) and a wide liner range of 0-1.817mM (R2 = 0.998). We further employed the recommended sensors in the real-time monitoring of HepG2 cells released O2•- under the stimulating of Zymosan (20mg/mL). Noticeably, the proposed sensors exhibit not only sensitive response but also stable current steps upon different addition of Zymosan. The calculated concentrations of cell-released O2•- vary from 6.772 to 24.652pM cell-1 for the Zymosan amount used in this work. The established novel sensors display low background current and signal noises, thus holding unique advantages in the trace analysis of O2•- in biological samples and in vivo environment.

3D graphene-based foam induced by phytic acid: An effective enzyme-mimic catalyst for electrochemical detection of cell-released superoxide anion

Here we present a new method to fabricate enzyme-mimic metal-free catalysts for electrochemical detection of superoxide anion (O2•-) by introducing phosphate groups into graphene-based foam. Through a template-free hydrothermal process, graphene oxide (GO) was treated with different amount of phytic acid (PA) to obtain 3D porous graphene-based foam (PAGF). Characterizations demonstrate that phosphate groups were successfully modified on the surface and inter layer structure of PAGF materials and the defects and disorder degree of PAGF could be controlled by adjusting the addition of PA precursors. Meanwhile, the synthesized PAGF was successfully immobilized on screen printed carbon electrodes (SPCEs) and employed in O2•- detection. With PA treated on graphene structure, the resulted PAGF/SPCEs exhibit distinct characteristic redox peaks, showing enzyme-mimic catalytic activity toward O2•- dismutation. Also, the amount of modified phosphate groups has caused a considerable variety on the performance of PAGF-based electrodes. Apart from high sensitivity, wide liner range, low detection limit, good selectivity and long-term stability, our sensors also present satisfying performance in the real-time monitoring of drug-induced O2•- released from Hela cells. The reliability of the biological measurement was further demonstrated via electron paramagnetic resonance (EPR) to characterize the released O2•- from stimulated cells by using 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) to trap the transient O2•-. The above results indicate that our established sensors hold potential application in the real-time detection of O2•- in biological samples.