RESUMO
The transport behavior of ions in the nanopores has an important impact on the performance of the electrochemical devices. Although the classical Transmission-Line (TL) model has long been used to describe ion transport in pores, the boundary conditions for the applicability of the TL model remain controversial. Here, we investigated the transport kinetics of different ions, within nanochannels of different lengths, by using transient single-particle imaging with temporal resolution up to microseconds. We found that the ion transport kinetics within short nanochannels may deviate significantly from the TL model. The reason is that the ion transport under nanoconfinement is composed of multi basic stages, and the kinetics differ much under different stage domination. With the shortening of nanochannels, the electrical double layer (EDL) formation would become the "rate-determining step" and dominate the apparent ion kinetics. Our results imply that using the TL model directly and treating the in-pore mobility as an unchanged parameter to estimate the ion transport kinetics in short nanopores/nanochannels may lead to orders of magnitude bias. These findings may advance the understanding of the nanoconfined ion transport and promote the related applications.
RESUMO
Single-nanoparticle electrochemistry offers electrochemical behaviors of individual entities beyond the ensemble system. An electric double layer (EDL) exists on any charged particle-liquid interface because of counter-ion accumulation, while direct measuring of the interfacial ion migration remains a challenge. Herein, a plasmonic-based transient microscopic method, with a temporal resolution of 1-2â µs, was demonstrated to directly track the ion migration dynamics on single charged nanoparticles. We found that the dynamics of EDL formation might deviate significantly from the prediction made by using the classical resistance-capacitance (RC) model under nanoscale and transient conditions. Under ultrafast charging, due to the limit migration rate of ions in the solution, the actual time scale of the EDL formation could be up to 5â times slower than the predicted value from the RC model. We then proposed a new theoretical model to describe the transient dynamics of EDL formation. These results may expand our current knowledge about nano-electrochemistry and transient electrochemistry.
RESUMO
Oxidative stress is a hallmark of secondary injury associated with spinal cord injury. Identifying stable and specific oxidative biomarkers is of important significance for studying spinal cord injury-associated secondary injury. Mature erythrocytes do not contain nuclei and mitochondria and cannot be transcribed and translated. Therefore, mature erythrocytes are highly sensitive to oxidative stress and may become a valuable biomarker. In the present study, we revealed the proteome dynamics of protein expression in erythrocytes of beagle dogs in the acute and subacute phases of spinal cord injury using mass spectrometry-based approaches. We found 26 proteins that were differentially expressed in the acute (0-3 days) and subacute (7-21 days) phases of spinal cord injury. Bioinformatics analysis revealed that these differentially expressed proteins were involved in glutathione metabolism, lipid metabolism, and pentose phosphate and other oxidative stress pathways. Western blot assays validated the differential expression of glutathione synthetase, transaldolase, and myeloperoxidase. This result was consistent with mass spectrometry results, suggesting that erythrocytes can be used as a novel sample source of biological markers of oxidative stress in spinal cord injury. Glutathione synthetase, transaldolase, and myeloperoxidase sourced from erythrocytes are potential biomarkers of oxidative stress after spinal cord injury. This study was approved by the Experimental Animal Centre of Ningxia Medical University, China (approval No. 2017-073) on February 13, 2017.
