MXenes Thin Films: From Fabrication to Their Applications

Facile Synthesis of Novel Ti2C Nano Bipyramids for Photothermal and Photodynamic Therapy of Breast Cancer

Photo-responsive synergetic therapeutics achieved significant attraction in cancer theranostic due to the versatile characteristics of nanomaterials. There have been substantial efforts in developing the simplest nano-design with exceptional synergistic properties and multifunctionalities. In this work, biocompatible Ti2C MXene nano bipyramids (MNBPs) were synthesized by hydrothermal method with dual functionalities of photothermal and photodynamic therapies. The MNBPs shape was obtained from two-dimensional (2D) Ti2C nanosheets by controlling the temperature of the reaction mixture. The structure of these Ti2C MNBPs was characterized by a high-resolution transmission electron microscope, scanning electron microscope, atomic force microscope, X-ray photoelectron spectroscopy, and X-ray diffraction. The Ti2C NBPs have shown exceptional photothermal properties with increased temperature to 72.3 °C under 808 nm laser irradiation. The designed nano bipyramids demonstrated excellent cellular uptake and biocompatibility. The Ti2C NBP has established a remarkable photothermal therapy (PTT) effect against 4T1 breast cancer cells. Moreover, Ti2C NBPs showed a profound response to UV light (6 mW/cm2) and produced reactive oxygen species, making them useful for photodynamic therapy (PDT). These in-vitro studies pave a new path to tune the properties of photo-responsive MXene nanosheets, indicating a potential use in biomedical applications.

Ambient Processed rGO/Ti3CNTx MXene Thin Film with High Oxidation Stability, Photosensitivity, and Self-Cleaning Potential

Solution-based processing offers advantages for producing thin films due to scalability, low cost, simplicity, and benignity to the environment. Here, we develop conductive and photoactivated self-cleaning reduced graphene oxide (rGO)/Ti3CNTx MXene thin films via spin coating under ambient conditions. The addition of a thin rGO layer on top of Ti3CNTx resulted in up to 45-fold improvement in the environmental stability of the film compared to the bare Ti3CNTx film. The optimized rGO/Ti3CNTx thin film exhibits an optical transmittance of 74% in the visible region of the spectrum and a sheet resistance of 19 kΩ/sq. The rGO/Ti3CNTx films show high rhodamine B discoloration activity upon light irradiation. Under UV irradiation, the electrically conductive MXene in combination with in situ formed semiconducting titanium oxide induces photogenerated charge carriers, which could potentially be used in photocatalysis. On the other hand, due to film transparency, white light irradiation can bleach the adsorbed dye via photolysis. This study opens the door for using MXene thin films as multifunctional coatings with conductive and potentially self-cleaning properties.

Can MXene be the Effective Nanomaterial Family for the Membrane and Adsorption Technologies to Reach a Sustainable Green World?

Environmental pollution has intensified and accelerated due to a steady increase in the number of industries, and exploring methods to remove hazardous contaminants, which can be typically divided into inorganic and organic compounds, have become inevitable. Therefore, the development of efficacious technology for the separation processes is of paramount importance to ensure the environmental remediation. Membrane and adsorption technologies garnered attention, especially with the use of novel and high performing nanomaterials, which provide a target-specific solution. Specifically, widespread use of MXene nanomaterials in membrane and adsorption technologies has emerged due to their intriguing characteristics, combined with outstanding separation performance. In this review, we demonstrated the intrinsic properties of the MXene family for several separation applications, namely, gas separation, solvent dehydration, dye removal, separation of oil-in-water emulsions, heavy metal ion removal, removal of radionuclides, desalination, and other prominent separation applications. We highlighted the recent advancements used to tune separation potential of the MXene family such as the manipulation of surface chemistry, delamination or intercalation methods, and fabrication of composite or nanocomposite materials. Moreover, we focused on the aspects of stability, fouling, regenerability, and swelling, which deserve special attention when the MXene family is implemented in membrane and adsorption-based separation applications.

Emerging Trends and Recent Progress of MXene as a Promising 2D Material for Point of Care (POC) Diagnostics

Two-dimensional (2D) nanomaterials with chemical and structural diversity have piqued the interest of the scientific community due to their superior photonic, mechanical, electrical, magnetic, and catalytic capabilities that distinguish them from their bulk counterparts. Among these 2D materials, two-dimensional (2D) transition metal carbides, carbonitrides, and nitrides with a general chemical formula of M_n+1X_nT_x (where n = 1-3), together known as MXenes, have gained tremendous popularity and demonstrated competitive performance in biosensing applications. In this review, we focus on the cutting-edge advances in MXene-related biomaterials, with a systematic summary on their design, synthesis, surface engineering approaches, unique properties, and biological properties. We particularly emphasize the property-activity-effect relationship of MXenes at the nano-bio interface. We also discuss the recent trends in the application of MXenes in accelerating the performance of conventional point of care (POC) devices towards more practical approaches as the next generation of POC tools. Finally, we explore in depth the existing problems, challenges, and potential for future improvement of MXene-based materials for POC testing, with the goal of facilitating their early realization of biological applications.