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One-step synthesis of robust 2D Ti3C2-MXene/AuNPs nanocomposite by electrostatic self-assembly for (bio)sensing
1 , 1 , 1, 2 , 1 , * 1 , 1
1  Department of Physics "E. Pancini", University of Naples Federico II, Naples, Italy
2  Scuola Superiore Meridionale (SSM), The University of Naples Federico II, Naples, Italy
Academic Editor: Manoj Gupta (registering DOI)

We present a single-step approach for the synthesis of Ti3C2 MXene and gold nanoparticle (AuNP) composites via electrostatic self-assembly. A unique challenge was addressed: the electrostatic repulsion between negatively charged Turkevich-synthesized AuNPs and negatively charged MXene sheets. We induced a positive charge on the AuNP surface using cetyltrimethylammonium bromide (CTAB), which enabled effective electrostatic interactions with the negatively charged surface of the MXene sheets. The success of AuNP surface modification with CTAB was confirmed via UV-Vis spectroscopy as well as the resulting MXene-AuNP composite. The as-synthesized MXene had a zeta potential of -34 mV, while the positively charged AuNPs displayed a potential of 25 mV. In contrast, the initial Turkevich-synthesized gold nanoparticles exhibited a charge of -30 mV. This charge alteration enabled the electrostatic self-assembly of the two components and gives a control over NPs count over MXene flakes. Notably, no AuNP peaks were observed at lower AuNP ratios in the composite. However, distinct peaks for both MXene and AuNPs appeared at an optimized ratio, confirming the successful formation of the composite. Scanning Electron Microscopy (SEM) images provided further insights into the successful formation of the composite with clearly visible AuNPs decorating the MXene matrix. Dynamic Light Scattering (DLS) measurements were performed for size analysis. These measurements revealed that MXene had an average size of 650 nm, consistent with literature but with a smaller flake size. AuNP exhibited dimensions of around 40 nm. In conclusion, our single-step synthesis method offers a sustainable platform for synthesizing MXene-AuNP composites with enhanced properties, rendering them suitable for a wide array of applications, notably in bio-sensing and nanomaterial-based technologies.

Keywords: Ti3C2 MXene;gold nanoparticle (AuNP);
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Samy Anwar