Theranostic 2D Tantalum Carbide (MXene)

Abstract

The large-dimensional and rigid ceramic bulks fabricated by high-temperature solid-phase reaction and sintering have never been considered for possibly entering and circulating within the blood vessels for biomedical applications, especially on combating cancer. Here, it is reported for the first time that MAX ceramic biomaterials exhibit unique functionalities for dual-mode photoacoustic/computed tomography imaging and are highly effective for in vivo photothermal ablation of tumors upon being exfoliated into ultrathin nanosheets within atomic thickness (MXene). As a paradigm, 2D ultrathin tantalum carbide nanosheets (Ta C MXenes) with nanosized lateral sizes are successfully synthesized based on a two-step liquid exfoliation strategy of MAX phase Ta AlC by combined hydrofluoric acid (HF) etching and probe sonication. The structural, electronic, and surface characteristics of the as-exfoliated nanosheets are revealed by various characterizations combined with first-principles calculations via density functional theory. Especially, the superior photothermal-conversion performance (efficiency η of 44.7%) and in vitro/in vivo photothermal ablation of tumor by biocompatible soybean phospholipid-modified Ta C nanosheets are systematically revealed and demonstrated. Based on the large family members of MXenes, this work may offer a paradigm that MXenes can achieve the specific biomedical applications (here, theranostic) providing that their compositions and nanostructures are carefully tuned and optimized to meet the strict requirements of biomedicine.

Silicene: Wet‐Chemical Exfoliation Synthesis and Biodegradable Tumor Nanomedicine

“…[9] The first synthesis of monolayer silicene was achieved on Ag(111) surface. [17] By analogy, 2D silicene, a hexagonal honeycomb lattice featuring non-planar buckled configuration, could be supposedly synthesized from the precursor Zintl-phase silicide (e.g., CaSi 2 ) via a topochemical deintercalation process of selective Ca-removal. …”

“…However, these as-synthesized silicene derived from epitaxial growth methods encounter three major drawbacks: scalable synthesis limitation, nonuniformity in vertical scale, and great difficulties in the transfer of layered materials from substrates. [17] By analogy, 2D silicene, a hexagonal honeycomb lattice featuring non-planar buckled configuration, could be supposedly synthesized from the precursor Zintl-phase silicide (e.g., CaSi 2 ) via a topochemical deintercalation process of selective Ca-removal. [16] Fortunately, these issues have been overcome by using selective extraction method upon converting MAX-phase layered compounds to versatile 2D MXene-phase nanosheets.…”

Solar Photothermal Electrodes for Highly Efficient Microbial Energy Harvesting at Low Ambient Temperatures

“…[15] Our results clearly indicated that the as-prepared photothermal electrode could efficiently raise the local temperature of the bioelectrode to approximately 30 8Cf rom low temperatures( i.e.,1 0, 15, and 20 8C) under simulated sunlight illumination,w hich enablede fficient microbial energy harvesting from the BESs at low operating temperatures. The photothermal electrode was prepared by coating MXene (Ti 3 C 2 T x )o nto ac arbon felt (CF) electrode (CF/MXene).…”

MXene‐Based Composites: Synthesis and Applications in Rechargeable Batteries and Supercapacitors

“…[106] The narrow bandgap of Ti 3 C 2 T x flakes indicates that Ti 3 C 2 T x flakes are semiconductors. [112] Apart from the properties mentioned above, MXenes show numerous attractive properties, such as adsorption, [111,113,114] ferromagnetism, [30,115] antibacterial activity, [116,117] thermoelectric property, [118] gas separation performance, [119] photothermalconversion capability, [120] etc. The conductivity of the Ti 3 C 2 T x flakes can reach as high as 6500 S cm −1 .…”