A Tumor-Microenvironment-Activated Nanozyme-Mediated Theranostic Nanoreactor for Imaging-Guided Combined Tumor Therapy

Activatable theranostic agents that can be activated by tumor microenvironment possess higher specificity and sensitivity. Here, activatable nanozyme-mediated 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) loaded ABTS@MIL-100/poly(vinylpyrrolidine) (AMP) nanoreactors (NRs) are developed for imaging-guided combined tumor therapy. The as-constructed AMP NRs can be specifically activated by the tumor microenvironment through a nanozyme-mediated "two-step rocket-launching-like" process to turn on its photoacoustic imaging signal and photothermal therapy (PTT) function. In addition, simultaneously producing hydroxyl radicals in response to the high H₂ O₂ level of the tumor microenvironment and disrupting intracellular glutathione (GSH) endows the AMP NRs with the ability of enhanced chemodynamic therapy (ECDT), thereby leading to more efficient therapeutic outcome in combination with tumor-triggered PTT. More importantly, the H₂ O₂ -activated and acid-enhanced properties enable the AMP NRs to be specific to tumors, leaving the normal tissues unharmed. These remarkable features of AMP NRs may open a new avenue to explore nanozyme-involved nanoreactors for intelligent, accurate, and noninvasive cancer theranostics.

Tuning Nanowires and Nanotubes for Efficient Fuel-Cell Electrocatalysis

Developing new synthetic methods for the controlled synthesis of Pt-based or non-Pt nanocatalysts with low or no Pt loading to facilitate sluggish cathodic oxygen reduction reaction (ORR) and organics oxidation reactions is the key in the development of fuel-cell technology. Various nanoparticles (NPs), with a range of size, shape, composition, and structure, have shown good potential to catalyze the sluggish cathodic and anodic reactions. In contrast to NPs, one-dimensional (1D) nanomaterials such as nanowires (NWs), and nanotubes (NTs), exhibit additional advantages associated with their anisotropy, unique structure, and surface properties. The prominent characteristics of NWs and NTs include fewer lattice boundaries, a lower number of surface defect sites, and easier electron and mass transport for better electrocatalytic activity and lower vulnerability to dissolution, Ostwald ripening, and aggregation than Pt NPs for enhanced stability. An overview of recent advances in tuning 1D nanostructured Pt-based, Pd-based, or 1D metal-free nanomaterials as advanced electrocatalysts is provided here, for boosting fuel-cell reactions with high activity and stability, including the oxygen reduction reaction (ORR), methanol oxidation reaction (MOR), and ethanol oxidation reaction (EOR). After highlighting the different strategies developed so far for the synthesis of Pt-based 1D nanomaterials with controlled size, shape, and composition, special emphasis is placed on the rational design of diverse NWs and NTs catalysts such as Pt-based NWs or NTs, non-Pt NTs, and carbon NTs with molecular engineering, etc. for enhancing the ORR, MOR, and EOR. Finally, some perspectives are highlighted on the development of more efficient fuel-cell electrocatalysts featuring high stability, low cost, and enhanced performance, which are the key factors in accelerating the commercialization of fuel-cell technology.

Bi-enzyme functionlized hollow PtCo nanochains as labels for an electrochemical aptasensor

In this work, a new signal amplification strategy based on hollow PtCo nanochains (HPtCoNCs) functionalized by bi-enzyme-horseradish peroxidase mimicking DNAzyme (HRP-DNAzyme) and glucose oxidase (GOD), as well as ferrocene-labeled secondary thrombin aptamer (Fc-TBA 2), is developed to construct a highly sensitive electrochemical aptasensor. The HRP-DNAzyme contains a special G-quadruplex structure with an intercalated hemin. With the surface area enlarged by HPtCoNCs, the amount of immobilized Fc-TBA 2, hemin and GOD can be enhanced. Under the enzyme catalysis of GOD, d-glucose is rapidly oxidized into gluconic acid accompanying with the generation of H₂O₂, which is further electrocatalyzed by Pt nanoparticles and HPR-DNAzyme to improve the electrochemical signal of Fc. With several amplification factors mentioned above, a wide linear ranged from 0.001 to 30 nM is acquired with a relatively low detection limit of 0.39 pM for thrombin. The present work demonstrates that using HPtCoNCs as labels is a promising way to amplify the analysis signal and improve the sensitivity of aptasensors.

Rapid fabrication of Au nanoparticle films with the aid of centrifugal force

In this work, rapid fabrication of Au nanoparticle (Au NP) films has been simply achieved by alternate adsorption of citrate-stabilized Au NPs and poly(diallyldimethylammonium chloride) with the aid of centrifugal force. In contrast to conventional electrostatic assembly, we carried out the assembly process in a centrifuge with a rotating speed of 4000 rpm, where centrifugal force can be imposed on Au NPs. Scanning electron microscopy and cyclic voltammetry were employed to characterize the assembly procedure and the thus-prepared thin solid films. Our results demonstrate that centrifugal force can promote the assembly of Au NPs and therefore enable the rapid fabrication of functional Au NP films. The thus-prepared Au NP films can serve as surface enhanced Raman scatting (SERS) substrates with tunable SERS signal intensity. This method is simple, rapid, and can be used as a general method to rapidly assemble other charged nanoparticles.