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 (Ta₄C₃ MXenes) with nanosized lateral sizes are successfully synthesized based on a two-step liquid exfoliation strategy of MAX phase Ta₄AlC₃ 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 Ta₄C₃ 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.

A novel MXene-based nanotheranostic agent, Ta₄C₃ nanosheets, is successfully synthesized based on a two-step liquid exfoliation strategy of the MAX phase Ta₄AlC₃ by combined HF etching and probe sonication. By the strong X-ray attenuation capability and high near-infrared optical absorbance of Ta₄C₃-soybean phospholipid nanosheets, largely enhanced in vivo X-ray computed tomography and photoacoustic dual-mode imaging of tumors after intravenous administration are achieved.

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