Advances on microfluidic paper-based electroanalytical devices.

Since the inception of the first electrochemical devices on paper substrates, many different reports of microfluidic paper-based electroanalytical devices (µPEDs), innovative hydrophobic barriers and electrode fabrication processes have allowed the incorporation of diverse materials, resulting in different applications and a boost in performance. These advancements have led to the creation of paper-based devices with comparable performance to many standard conventional devices, with the added benefits of pumpless fluidic transport, component separation and reagent storage that can be exploited to automate and handle sample preprocessing. Herein, we review µPEDs, summarize the characteristics and functionalities of µPEDs, such as separation, fluid flow control and storage, and outline the conventional and emerging fabrication and modification approaches for µPEDs. We also examine the recent application of µPEDs in biomedicine, the environment, and food and water safety, as well as some limitations and challenges that must be addressed.

MXenes: state-of-the-art synthesis, composites and bioapplications.

MXenes have shown significant potential in a multitude of scientific domains as they provide substantial benefits over carbon graphene, such as ease of production and functionalization, large surface area, adjustable properties, biocompatibility and hydrophilicity. The morphologies and physicochemical properties of MXenes vary with the synthesis procedures and conditions. Very recently, unique hybrid MXene-based nanocomposites have been produced and applied in a variety of fields. Herein, we review the synthesis of MXenes from traditional chemical exfoliation methods to newly developing fluoride-independent hydrothermal methods, summarize the properties of the synthesized MXenes, including stability and oxidative sensitivity, and outline emerging approaches for MXene-based nanocomposites. We also elaborate the up-to-date bio-applications of MXenes in photothermal therapy, bio-imaging, sensing, and drug delivery, as well as the practical hurdles that must be addressed.