Designed Synthesis of Aptamer-Immobilized Magnetic Mesoporous Silica/Au Nanocomposites for Highly Selective Enrichment and Detection of Insulin

We designed and synthesized aptamer-immobilized magnetic mesoporous silica/Au nanocomposites (MMANs) for highly selective detection of unlabeled insulin in complex biological media using MALDI-TOF MS. The aptamer was easily anchored onto the gold nanoparticles in the mesochannels of MMANs with high capacity for highly efficient and specific enrichment of insulin. With the benefit from the size-exclusion effect of the mesoporous silica shell with a narrow pore size distribution (∼2.9 nm), insulin could be selectively detected despite interference from seven untargeted proteins with different size dimensions. This method exhibited an excellent response for insulin in the range 2–1000 ng mL^–1. Moreover, good recoveries in the detection of insulin in 20-fold diluted human serum were achieved. We anticipate that this novel method could be extended to other biomarkers of interest and potentially applied in disease diagnostics

Defect Chemistry of the Metal Cation Defects in the p- and n‑Doped SnO₂ Nanocrystalline Films

Cationic interstitial and substitutional defects, which serve as a key role in shaping the material’s performance, are considered as two kinds of important defect structures in the doped SnO₂. To give a clear characterization of such metal cation defects, temperature-dependent electrical conduction measurement by the high throughput screening platform of gas-sensing materials is carried out, for the first time, to perform the defect structure studies of the p-type (Li⁺, Cd²⁺, Al³⁺), isovalent (Ti⁴⁺), and n-type (Nb⁵⁺, W⁶⁺) doped SnO₂ nanocrystalline films in the oxygen-free atmosphere. The temperature-dependent measurements indicate that subtle induced impurities are capable of evidently modifying the electrical conduction mechanism of the SnO₂. In terms of the small-polaron hopping mechanism, an improved defect chemical model is proposed in which the properties of the metal cation defects are explicitly depicted. Values for the ionization energy (Δ<i>E_D</i>) of the metal cation defects and electron hopping energy (<i>E_H</i>) in the doped SnO₂ are extracted by fitting the experimental data to the defect model. These data that reflect the nature of the metal cation defects and their effects on the electronic structure of the SnO₂ are first introduced here, and the validity of these data are confirmed. What’s more, the Δ<i>E_D</i> calculated here is of critical importance for understanding the defect structure of the metal dopants in the SnO₂

Electrospun TiO₂/C Nanofibers As a High-Capacity and Cycle-Stable Anode for Sodium-Ion Batteries

Nanosized TiO₂ is now actively developed as a low-cost and potentially high capacity anode material of Na-ion batteries, but its poor capacity utilization and insufficient cyclability remains an obstacle for battery applications. To overcome these drawbacks, we synthesized electrospun TiO₂/C nanofibers, where anatase TiO₂ nanocrystals with a diameter of ∼12 nm were densely embedded in the conductive carbon fibers, thus preventing them from aggregating and attacking by electrolyte. Due to its abundant active surfaces of well-dispersed TiO₂ nanocrytals and high electronic conductivity of the carbon matrix, the TiO₂/C anode shows a high redox capacity of ∼302.4 mA h g^–1 and a high-rate capability of 164.9 mAh g^–1 at a very high current of 2000 mA g^–1. More significantly, this TiO₂/C anode can be cycled with nearly 100% capacity retention over 1000 cycles, showing a sufficiently long cycle life for battery applications. The nanofibrous architecture of the TiO₂/C composite and its superior electrochemical performance may provide new insights for development of better host materials for practical Na-ion batteries

Synergistic Na-Storage Reactions in Sn₄P₃ as a High-Capacity, Cycle-stable Anode of Na-Ion Batteries

Room-temperature Na-ion batteries have attracted great interest as a low cost and environmentally benign technology for large scale electric energy storage, however their development is hindered by the lack of suitable anodic host materials. In this paper, we described a green approach for the synthesis of Sn₄P₃/C nanocomposite and demonstrated its excellent Na-storage performance as a novel anode of Na-ion batteries. This Sn₄P₃/C anode can deliver a very high reversible capacity of 850 mA h g^–1 with a remarkable rate capability with 50% capacity output at 500 mA g^–1 and can also be cycled with 86% capacity retention over 150 cycles due to a synergistic Na-storage mechanism in the Sn₄P₃ anode, where the Sn nanoparticles act as electronic channels to enable electrochemical activation of the P component, while the elemental P and its sodiated product Na₃P serve as a host matrix to alleviate the aggregation of the Sn particles during Na insertion reaction. This mechanism may offer a new approach to create high capacity and cycle-stable alloy anodes for Na-ion batteries and other electrochemical energy storage applications

Fe₂(MoO₄)₃ as an Effective Photo-Fenton-like Catalyst for the Degradation of Anionic and Cationic Dyes in a Wide pH Range

The photocatalytic activity of Fe₂(MoO₄)₃ under visible light (λ > 400 nm) was evaluated by the degradation of Acid Orange II (AOII) and Methylene Blue (MB). This new catalyst is highly effective for the degradation of both dyes in H₂O₂/visible light system at neutral pH. One hundred mg/L of dyes was almost removed within 30 min. Compared to the results in the darkness, the rate constants fitted by a simple pseudo-first-order reaction for both dyes multiplied. MB degraded at a slightly lower rate than AOII under identical conditions due to different chemical structures. Particularly, a high photocatalytic activity of Fe₂(MoO₄)₃ was obtained in a wide pH range of 3.0–9.0 and thus acidification pretreatment was not necessary. The high catalytic activity could be attributed to the strong absorption of Fe₂(MoO₄)₃ in the visible-light region and in addition, the generation of reactive ·OH from H₂O₂ synergistically activated by both Fe³⁺ and MoO₄^2–