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A highly sensitive electrochemical biosensor was manufactured with triple synergistic catalysis to detect hydrogen peroxide (H

In this study we show for the first time that a reduced graphene oxide (rGO) carrier has a 15-fold higher catalysis rate than graphene oxide (GO) in Ag+ reduction. Based on this, we constructed a tumor microenvironment-enabled in situ silver-based electrochemical oncolytic bioreactor (SEOB) which unlocked an Ag+ prodrug to generate silver nanoparticles and inhibited the growth of various tumors. In this bioreactor system, intratumoral H2O2 acted as the reductant and the rGO carrier acted as the catalyst. Chelation of aptamers to this prodrug increased the production of silver nanoparticles by tumor cells, especially in the presence of Vitamin C, which broke down in tumor cells to supply massive amounts of H2O2. Consequently, highly efficient silver nanoparticle-induced apoptosis was observed in HepG2 and A549 cells in vitro and in HepG2- and A549-derived tumors in vivo. The apoptosis was associated with ROS-induced changes in mitochondrial membrane potential and DNA damage. The specific aptamer targeting and intratumoral silver nanoparticle production guaranteed excellent biosafety, with no damage to normal cells, because the Ag+ prodrug was specifically unlocked in tumors. More significantly, there was no evident tissue damage in monkeys, which greatly increases the clinical translation potential of the SEOB system.

Distributed storage employs replication to mask failures and improve availability. However, these systems typically exhibit a hard tradeoff between consistency and performance. Ensuring consistency introduces coordination overhead, and as a result the system throughput does not scale with the number of replicas. We present Harmonia, a replicated storage architecture that exploits the capability of new-generation programmable switches to obviate this tradeoff by providing near-linear scalability without sacrificing consistency. To achieve this goal, Harmonia detects read-write conflicts in the network, which enables any replica to serve reads for objects with no pending writes. Harmonia implements this functionality at line rate, thus imposing no performance overhead. We have implemented a prototype of Harmonia on a cluster of commodity servers connected by a Barefoot Tofino switch, and have integrated it with Redis. We demonstrate the generality of our approach by supporting a variety of replication protocols, including primary-backup, chain replication, Viewstamped Replication, and NOPaxos. Experimental results show that Harmonia improves the throughput of these protocols by up to 10 x for a replication factor of 10, providing near-linear scalability up to the limit of our testbed.

In the present work, a sensitive electrochemical aptasensor was designed for the detection of adenosine triphosphate (ATP) with hemin/graphene oxide nanosheets (HGNs). Firstly, the ATP aptamer was self-assembled on gold electrode surface, and then HGNs were captured to the modified electrode by π-π stacking. The captured HGNs could catalyze the disproportionation reaction of H2O2, and produced a detectable electrochemical signal by chronoamperometry. ATP was competitively bound to aptamer which led to the release of HGNs from the electrode surface after adding ATP. The decrease of the electrochemical signal, which was calculated by the difference of amperometric responses before and after incubation of ATP, provided a quantitative signal for ATP detection. A linear correlation was achieved between the difference of the amperometric responses and the logarithmic concentration of ATP ranging from 0.5 to 100 nM with a detection limit of 0.08 nM. Besides, the aptasensor also exhibited good selectivity toward ATP against other analogs.

A highly sensitive non-enzymatic electrochemical sensor based on platinum nanoparticles/reduced graphene oxide-chitosan-ferrocene carboxylic acid nano-hybrids (Pt NPs/RGO-CS-Fc biosensor) was developed for the measurement of hydrogen peroxide (H2O2). The RGO-CS-Fc nano-hybrids was prepared and characterized by UV-vis spectrum, Fourier transform infrared spectroscopy, transmission electron microscopy, Raman spectrometer and electrochemical impedance spectroscopy. Under optimal experimental conditions, the Pt NPs/RGO-CS-Fc biosensor showed outstanding catalytic activity toward H2O2 reduction. The current response of the biosensor presented a linear relationship with H2O2 concentration from 2.0×10(-8)M to 3.0×10(-6)M with a correlation coefficient of R(2)=0.9968 and with logarithm of H2O2 concentration from 6.0×10(-6)M to 1.0×10(-2)M with a correlation coefficient of R(2)=0.9887, the low detection limit of 20nM was obtained at the signal/noise (S/N) ratio of 3. Moreover, the Pt NPs/RGO-CS-Fc biosensor exhibited excellent anti-interference capability and reproducibility for the detection of H2O2. The biosensor was also successfully applied for the detection of H2O2 from living cells containing normal and cancer cells. All these results prove that the Pt NPs/RGO-CS-Fc biosensor has the potential application in clinical diagnostics to evaluate oxidative stress of different living cells.

The hardness and thermal stability are the important problems of the cast Al–Cu alloy related to the microstructural changes. In order to increase the possibilities of high temperature applications of the cast Al–Cu alloy, it is necessary to gain a more detail understanding of the correlation between the age hardening and the microstructure in the cast Al–Cu alloy, and the thermal stability of the θ′ precipitates at elevated temperatures. The aim of this work is to investigate the effects of La addition on the age hardening behavior and precipitation kinetics in the Al–Cu alloy in the temperature range from 435 to 523 K. The results indicated that La addition considerably increases the number of the θ′ precipitates and decreases their sizes, which results in the enhanced age hardening effect. The precipitation kinetics analysis showed that the activation energy (13 kJ/mol) of the θ′ precipitate nucleation of the modified alloy is smaller than that (19 kJ/mol) of the unmodified alloy. The decrease in the activation energy of the θ′ precipitate nucleation can be explained with both the enhanced nucleation process due to La/Cu/vacancy aggregating and the increased interaction between Al and Cu atoms.