ABSTRACT
Recent reviews described the efficient syntheses of metallic bismuth nanoparticles. Nevertheless, few studies have been published on the medical applications of these nanoparticles compared to the number of studies on the well-documented clinical use of the bismuth(III) complex. An analysis of the literature revealed the significant potential of metallic bismuth nanoparticles in different theranostic applications. In the diagnostic field, preclinical proofs of concept have been demonstrated for X-ray, photoacoustic and fluorescence imaging. In the therapeutic field, several preclinical studies have shown the potential of bismuth nanoparticles as X-ray radiosensitizers for use in radiotherapy and as photothermal agents for applications in near infrared phototherapy. The properties of these metallic bismuth nanoparticles as bactericidal, fungicidal, antiparasitic and antibiofilm agents have also been studied. Although information concerning the toxic effects of these nanoparticles has been collected, these data are insufficient when considering the immediate clinical use of these new nanoparticles.
ABSTRACT
Bismuth is a highly biocompatible and inexpensive metal with a high atomic number, which confers an important X-rays opacity. While bismuth oxide or bismuth sulphide have been extensively studied in imaging, little is known about metallic bismuth nanoparticles. The latter are more attractive for X-rays imaging because they contain neither oxygen nor sulfur, so that a high amount of metal atoms is contained within the nanoparticles. We report here a robust, efficient and green ultrasound assisted synthesis to obtain metallic bismuth NPs. The procedure, which has been optimized to get a reproducible synthesis, will also tend to minimize chemical hazards to health and environment. By applying the green chemistry principles, several experimental parameters have been studied such as reaction time, reactants stoichiometry, temperature, starting material quantities and purification steps number. Two energy delivery system (classical heating and sonication) were compared. The production of small metallic bismuth NPs on a large scale by flow chemistry coupled to sonication was showed for the first time. These optimizations of the process were completed by a comparison of two purification methods (centrifugation and ultrafiltration) to isolate purified thin black powders of d-glucose-coated bismuth NPs. Several analytical techniques were used to characterize products (structures, sizes and morphology) such as Fourier Transform InfraRed (FT-IR) spectroscopy, Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectrometry (EDX) and X-Ray Diffraction (XRD). All these analyses corroborated well with the structure of metallic bismuth NPs coated with a d-glucose shell.
