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Electroporation temporarily enhances cell membrane permeability and promotes the absorption of external molecules. We have developed a device termed the rolling microneedle electrode array (RoMEA) that combines a densely arranged microneedle array of electrodes with rolling structures. Use RoMEA to create uniform skin micropores for efficient, low-damage transfection of nucleic acids over extended areas of the body. We describe in detail the design, fabrication, and assembly of the device and the application of in vivoelectroporation of nucleic acids.

Highlights :

Polyimide-based flexible microneedle array (PI-MNA) electrodes realize high electrical/mechanical performance and are compatible with wearable wireless recording systems.

The normalized electrode–skin interface impedance (EII) of the PI-MNA electrodes reaches 0.98 kΩ cm2at 1 kHz and 1.50 kΩ cm2at 10 Hz, approximately 1/250 of clinical standard electrodes.

This is the first report on the clinical study of microneedle electrodes. The PI-MNA electrodes are applied to clinical long-term continuous monitoring for polysomnography. Abstract: Microneedle array (MNA) electrodes are an effective solution to achieve high-quality surface biopotential recording without the coordination of conductive gel and are thus very suitable for long-term wearable applications. Existing schemes are limited by flexibility, biosafety, and manufacturing costs, which create large barriers for wider applications. Here, we present a novel flexible MNA electrode that can simultaneously achieve flexibility of the substrate to fit a curved body surface, robustness of microneedles to penetrate the skin without fracture, and a simplified process to allow mass production. The compatibility with wearable wireless systems and the short preparation time of the electrodes significantly improves the comfort and convenience of electrophysiological recording. The normalized electrode–skin contact impedance reaches 0.98 kΩ cm2at 1 kHz and 1.50 kΩ cm2at 10 Hz, a record low value compared to previous reports and approximately 1/250 of the standard electrodes. The morphology, biosafety, and electrical/mechanical properties are fully characterized, and wearable recordings with a high signal-to-noise ratio and low motion artifacts are realized. The first reported clinical study of microneedle electrodes for surface electrophysiological monitoring was conducted in tens of healthy and sleep-disordered subjects with 44 nights of recording (over 8 h per night), providing substantial evidence that the electrodes can be leveraged to substitute for clinical standard electrodes.

A fast method to detect and sequence photomodified oligodeoxynucleotides (ODNs) by exonuclease digestion and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is reported. Upon treatment of modified ODNs with both phosphodiesterase I and phosphodiesterase II, the digestion stops at the sites of photomodification. Post-source decay (PSD) of MALDI-produced ions from two enzymatic digestion end products distinguishes isomers such as 5'-d(T[cis-syn]TAAGC) and 5'-d(CGAAT[cis-syn]T), which have symmetrical or identical compositions at the 3' and 5' ends, respectively. Studies have also been done to follow the kinetics for enzyme degradation of photomodified ODNs. The calculated rate constants from a mathematical treatment of the time-dependent MALDI data clearly show that the enzymatic digestion rate slows as the enzyme approaches the modified site.

Abstract: A fast method to detect and sequence photomodified oligodeoxynucleotides (ODNs) by exonuclease digestion and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is reported. Upon treatment of modified ODNs with both phosphodiesterase I and phosphodiesterase II, the digestion stops at the sites of photomodification. Post-source decay (PSD) of MALDI-produced ions from two enzymatic digestion end products distinguishes isomers such as 5'-d(T[cis-syn]TAAGC) and 5'-d(CGAAT[cis-syn]T), which have symmetrical or identical compositions at the 3' and 5' ends, respectively. Studies have also been done to follow the kinetics for enzyme degradation of photomodified ODNs. The calculated rate constants from a mathematical treatment of the time-dependent MALDI data clearly show that the enzymatic digestion rate slows as the enzyme approaches the modified site.

The CeO2, Ce-Nb-Oxand Nb2O5catalysts were synthesized by citric acid method to investigate the promotion effect of Nb on ceria for selective catalytic reduction (SCR) of NO with NH3. The catalytic activity measurements indicate that the mixed oxide Ce-Nb-Oxpresents a higher SCR activity than the single oxide CeO2or Nb2O5catalyst. In addition, the Ce-Nb-Oxcatalyst shows a high resistance towards H2O and SO2at 280 °C. The Raman, X-ray photoelectron spectra and temperature programmed reduction with H2results indicate that the incorporation of Nb provides abundant oxygen vacancies for capturing more surface adsorbed oxygen, which provides a superior redox capability and accelerates the renewal of active sites. Furthermore, the Fourier transform infrared spectra and temperature programmed desorption of NH3results suggest that niobium pentoxide shows high surface acidity, which is partly retained in the Ce-Nb-Oxcatalyst possessing a high content of Lewis and Brønsted acid sites. Therefore, the incorporation of Nb improves both the redox and acidic capacities of Ce-Nb-Oxcatalyst for the SCR reaction. Here, the redox behavior is primarily taken on Ce and the acidity is well improved by Nb, so the synergistic effect should exist between Ce and Nb. In terms of the reaction mechanism, in situDRIFT experiments suggest that both NH3on Lewis acid sites and NH4+on Brønsted acid sites can react with NO species, and adsorbed NO and NO2species can both be reduced by NH3. In the SCR process, O2as an important role primarily acts as the accelerant to improve the redox and acid cycles. This work proves that the combination of redox and acidic properties of different constituents can be feasible for catalyst design to obtain a superior SCR performance.