In this Review, we aim to provide an updated summary of the research related to hollow micro- and nanostructures, covering both their synthesis and their applications. After a brief introduction to the definition and classification of the hollow micro-/nanostructures, we discuss various synthetic strategies that can be grouped into three major categories, including hard templating, soft templating, and self-templating synthesis. For both hard and soft templating strategies, we focus on how different types of templates are generated and then used for creating hollow structures. At the end of each section, the structural and morphological control over the product is discussed. For the self-templating strategy, we survey a number of unconventional synthetic methods, such as surface-protected etching, Ostwald ripening, the Kirkendall effect, and galvanic replacement. We then discuss the unique properties and niche applications of the hollow structures in diverse fields, including micro-/nanocontainers and reactors, optical properties and applications, magnetic properties, energy storage, catalysis, biomedical applications, environmental remediation, and sensors. Finally, we provide a perspective on future development in the research relevant to hollow micro-/nanostructures.

With the increasing interests of using graphene and its derivatives in the area of biomedicine, the systematic evaluation of their potential risks and impacts to biological systems is becoming critically important. In this work, we carefully study how surface coatings affect the cytotoxicity and extracellular biodegradation behaviors of graphene oxide (GO) and its derivatives. Although naked GO could induce significant toxicity to macrophages, coating those two-dimensional nanomaterials with biocompatible macromolecules such as polyethylene glycol (PEG) or bovine serum albumin (BSA) could greatly attenuate their toxicity, as independently evidenced by several different assay approaches. On the other hand, although GO can be gradually degraded through enzyme induced oxidization by horseradish peroxidase (HRP), both PEG and BSA coated GO or reduced GO (RGO) are rather resistant to HRP-induced biodegradation. In order to obtain biocompatible functionalized GO that can still undergo enzymatic degradation, we conjugate PEG to GO via a cleavable disulfide bond, obtaining GO-SS-PEG with negligible toxicity and considerable degradability, promising for further biomedical applications.

Benzofuran compounds are a class of compounds that are ubiquitous in nature.

Nano-TiO2 was prepared in [Bmim]BF4 ionic liquid (IL) via microwave radiation. The [Bmim]BF4 IL that contained the as-prepared TiO2 was mixed with dibenzothiophene (DBT) in n-octane, which was used as model oil for photocatalytic desulfurization under the UV irradiation. In this process, IL was used not only as microwave absorption medium for preparation of TiO2 but also as extractant for DBT. The effect of microwave time on the photocatalytic desulfurization ability of prepared TiO2 in the presence of O2 was investigated. 98.2% and 94.3% sulfur could be removed from model oil and actual diesel oil, respectively, in 10 h UV irradiation under the conditions that V(IL)/V(oil) = 1:5, air flow = 200 mL/min. The [Bmim]BF4 IL was recycled five times with a slight decrease in desulfurization efficiency.