Laser Ablation-Assisted Synthesis of Plasmonic Si@Au Core-Satellite Nanocomposites for Biomedical Applications

• Main Authors: Ahmed Al-Kattan, Gleb Tselikov, Khaled Metwally, Anton A. Popov, Serge Mensah, Andrei V. Kabashin
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Nanomaterials
• Subjects: pulsed laser ablation in liquids; Si@Au core-satellite; core-shell; plasmonic nanoparticles; Mie theory; biomedical applications
• Online Access: https://www.mdpi.com/2079-4991/11/3/592

Owing to strong plasmonic absorption and excellent biocompatibility, gold nanostructures are among best candidates for photoacoustic bioimaging and photothermal therapy, but such applications require ultrapure Au-based nanoformulations of complex geometry (core-shells, nanorods) in order to shift the absorption band toward the region of relative tissue transparency (650–1000 nm). Here, we present a methodology for the fabrication of Si@Au core-satellite nanostructures, comprising of a Si core covered with small Au nanoparticles (NP), based on laser ablative synthesis of Si and Au NPs in water/ethanol solutions, followed by a chemical modification of the Si NPs by 3-aminopropyltrimethoxysilane (APTMS) and their subsequent decoration by the Au NPs. We show that the formed core-satellites have a red-shifted plasmonic absorption feature compared to that of pure Au NPs (520 nm), with the position of the peak depending on APTMS amount, water−ethanol solvent percentage and Si−Au volume ratio. As an example, even relatively small 40-nm core-satellites (34 nm Si core + 4 nm Au shell) provided a much red shifted peak centered around 610 nm and having a large tail over 700 nm. The generation of the plasmonic peak is confirmed by modeling of Si@Au core-shells of relevant parameters via Mie theory. Being relatively small and exempt of any toxic impurity due to ultraclean laser synthesis, the Si@Au core-satellites promise a major advancement of imaging and phototherapy modalities based on plasmonic properties of nanomaterials.