Lanthanide-doped upconversion nanocrystals enable anti-Stokes emission with pump intensities several orders of magnitude lower than required by conventional nonlinear optical techniques. Their exceptional properties, namely large anti-Stokes shifts, sharp emission spectra and long excited-state lifetimes, have led to a diversity of applications. Here, we review upconversion nanocrystals from the perspective of fundamental concepts and examine the technical challenges in relation to emission colour tuning and luminescence enhancement. In particular, we highlight the advances in functionalization strategies that enable the broad utility of upconversion nanocrystals for multimodal imaging, cancer therapy, volumetric displays and photonics.

Single-atom catalysts (SACs) have great potential in electrocatalysis.Their performance can be rationally optimized by tailoring the metal atoms,a djacent coordinative dopants, and metal loading. However,doing so is still agreat challenge because of the limited synthesis approach and insufficient understanding of the structure-property relationships.H erein, we report an ew kind of Mo SACw ith au nique O,S coordination and ah igh metal loading over 10 wt %. The isolation and local environment was identified by high-angle annular dark-field scanning transmission electron microscopy and extended X-ray absorption fine structure.T he SACs catalyze the oxygen reduction reaction (ORR) via a2 e À pathway with ah igh H 2 O 2 selectivity of over 95 %i n0 .10 m KOH. The critical role of the Mo single atoms and the coordination structure was revealed by both electrochemical tests and theoretical calculations. Figure 4. Reaction mechanism of single Mo atom supported by O,Sdoped graphene substrate. a) Free energy diagram of 2e À ORR on three investigated substrates at equilibriumpotential of the reaction. b) Atomic configuration of OOH* adsorption on Mo-O 3 S-C. c) Atomic configuration of OOH* adsorptiono nMo-S 4 -C.

Functionalized dendrimer-like hybrid silica nanoparticles with hierarchical pores are designed and synthesized. The unique structure, large surface area, and excellent biocompability render such materials attractive nanocarriers for the advanced delivery of various sized drugs and genes simultaneously.

Although proton exchange membrane (PEM) water electrolyzers offer a promising means for generation of hydrogen fuel from solar and wind energy, in acidic environments the corresponding anodic oxygen evolution reaction (OER) remains a bottleneck. Because the activity and stability of electrocatalysts depend significantly on physicochemical properties, material surface and interface engineering can offer a practical way to boost performance. To date, significant advances have been made using a judicious combination of advanced theoretical computations and spectroscopic characterizations. To provide a critical assessment of this field, we focus on the establishment of material property− catalytic activity relationships. We start with a detailed exploration of prevailing OER mechanisms in acid solution through evaluating the role of catalyst lattice oxygen. We then critically review advances in surface and interface engineering in acidic OER electrocatalysts from both experimental and theoretical perspectives. Finally, a few promising research orientations are proposed to inspire future investigation of high-performance PEM catalysts.

After more than 20 years of intensive investigations, gene therapy has become one of the most promising strategies for treating genetic diseases. However, the lack of ideal delivery systems has limited the clinical realization of gene therapy's tremendous potential, especially for DNA-based gene therapy. Over the past decade, considerable advances have been made in the application of polymer-based DNA delivery systems for gene therapy, especially through multifunctional systems. The core concept behind multifunctional polymeric DNA delivery systems is to endow one single DNA carrier, via materials engineering and surface modification, with several active functions, e.g., good cargo DNA protection, excellent colloidal stability, high cellular uptake efficiency, efficient endo/lysosome escape, effective import into the nucleus, and DNA unpacking. Such specially developed vectors would be capable of overcoming multiple barriers to the successful delivery of DNA. In this review, we first provide a comprehensive overview of the interactions between the protein corona and DNA vectors, the mechanisms and challenges of nonviral DNA vectors, and important concepts in the design of DNA carriers identified via past reports on DNA delivery systems. Finally, we highlight and discuss recent advances in multifunctional polymeric DNA delivery systems based on "off-the-shelf" polycations including polyethylenimine (PEI), poly-l-lysine (PLL), and chitosan and offer perspectives on future developments.

Spurred by recent progress in medicinal chemistry, numerous lead compounds have sprung up in the past few years, although the majority are hindered by hydrophobicity, which greatly challenges druggability. In an effort to assess the potential of platinum (Pt) candidates, the nanosizing approach to alter the pharmacology of hydrophobic Pt(IV) prodrugs in discovery and development settings is described. The construction of a self-assembled nanoparticle (NP) platform, composed of amphiphilic lipid-polyethylene glycol (PEG) for effective delivery of Pt(IV) prodrugs capable of resisting thiol-mediated detoxification through a glutathione (GSH)-exhausting effect, offers a *

Light is a particularly appealing tool for on-demand drug delivery due to its noninvasive nature, ease of application, and exquisite temporal and spatial control. Great progress is achieved in the development of novel light-driven drug delivery strategies with both breadth and depth. Light-controlled drug delivery platforms can be generally categorized into three groups: photochemical, photothermal, and photoisomerization-mediated therapies. Various advanced materials, such as metal nanoparticles, metal sulfides and oxides, metal-organic frameworks, carbon nanomaterials, upconversion nanoparticles, semiconductor nanoparticles, stimuli-responsive micelles, polymer-and liposome-based nanoparticles are applied for light-stimulated drug delivery. In view of the increasing interest in on-demand targeted drug delivery, the development of light-responsive systems with a focus on recent advances, key limitations, and future directions is reviewed.

Clay-based nanomaterials, especially 2:1 aluminosilicates such as vermiculite, biotite, and illite, have demonstrated great potential in various fields. However, their characteristic sandwiched structures and the lack of effective methods to exfoliate two-dimensional (2D) functional core layers (FCLs) greatly limit their future applications. Herein, we present a universal wet-chemical exfoliation method based on alkali etching that can intelligently “capture” the ultrathin and biocompatible FCLs (MgO and Fe2O3) sandwiched between two identical tetrahedral layers (SiO2 and Al2O3) from vermiculite. Without the sandwich structures that shielded their active sites, the obtained FCL nanosheets (NSs) exhibit a tunable and appropriate electron band structure (with the bandgap decreased from 2.0 eV to 1.4 eV), a conductive band that increased from −0.4 eV to −0.6 eV, and excellent light response characteristics. The great properties of 2D FCL NSs endow them with exciting potential in diverse applications including energy, photocatalysis, and biomedical engineering. This study specifically highlights their application in cancer theranostics as an example, potentially serving as a prelude to future extensive studies of 2D FCL NSs.