Scalable Synthesis of Biodegradable Black Mesoporous Silicon Nanoparticles for Highly Efficient Photothermal Therapy.

Wujun Xu,Maija-Riitta Hirvonen,Konstantin Tamarov,Sari Granroth,Vesa-Pekka Lehto,Sirpa Peräniemi,Li Fan,Tuomo Nissinen,Oskari Uski,Jimi Rantanen

doi:10.1021/acsami.8b04557

Abstract

Porous silicon (PSi) has attracted wide interest as a potential material for various fields of nanomedicine. However, until now, the application of PSi in photothermal therapy has not been successful due to its low photothermal conversion efficiency. In the present study, biodegradable black PSi (BPSi) nanoparticles were designed and prepared via a high-yield and simple reaction. The PSi nanoparticles possessed a low band gap of 1.34 eV, a high extinction coefficient of 13.2 L/g/cm at 808 nm, a high photothermal conversion efficiency of 33.6%, good photostability, and a large surface area. The nanoparticles had not only excellent photothermal properties surpassing most of the present inorganic photothermal conversion agents (PCAs) but they also displayed good biodegradability, a common problem encountered with the inorganic PCAs. The functionality of the BPSi nanoparticles in photothermal therapy was verified in tumor-bearing mice in vivo. These results showed clearly that the photothermal treatment was highly efficient to inhibit tumor growth. The designed PCA material of BPSi is robust, easy to prepare, biocompatible, and therapeutically extremely efficient and it can be integrated with several other functionalities on the basis of simple silicon chemistry.

Highlights

Photothermal therapy (PTT) is an attractive approach to treat various tumors.[1−4] Photothermal conversion agents (PCAs) absorb and convert light into heat, resulting in rapid and local ablation of cancerous cells
The reaction between NaSi and NH4Br has been developed as a low-cost method to prepare ultra-small silicon nanoparticles in a high-boiling-point organic solvent.[28]
The ultrasmall silicon nanoparticles were monodispersed in the organic solvent after the reaction

Summary

Introduction

Photothermal therapy (PTT) is an attractive approach to treat various tumors.[1−4] Photothermal conversion agents (PCAs) absorb and convert light into heat, resulting in rapid and local ablation of cancerous cells. Near-infrared (NIR, 650−900 nm) light is generally utilized to achieve deep tissue penetration as well as to minimize the heating of nontarget tissues.[4] Many types of PCAs, including organic compounds[5−7] and inorganic materials,[2,8] have been developed for PTT applications. Organic PCAs such as indocyanine green have shown promising photothermal features and good biocompatibilities. These materials often suffer from photobleaching and low photothermal conversion efficiency. One drawback associated with all of these inorganic PCAs is that they typically degrade very slowly in biological conditions. This feature has aroused concerns about safety and biocompatibility, especially since it may be accompanied by the accumulation of heavy metals from some metal sulfides. The development of novel PCAs combining all desired positive features is highly needed

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Results

Conclusion