Silver chalcogenide nanoparticles: a review of their biomedical applications

Silver chalcogenide (Ag₂X, where X = S, Se, or Te) nanoparticles have been extensively investigated for their applications in electronics but have only recently been explored for biomedical applications. In the past 10 years, Ag₂X, primarily silver sulfides at first, have become of great importance as quantum dots, since they not only possess excellent deep tissue imaging properties in the near-infrared regions I and II, but also have low toxicities. Their appealing properties have led to numerous recent developments of Ag₂X for biomedical applications. Furthermore, Ag₂X have been discovered in the past 2-3 years to be potent X-ray contrast agents, adding to the numerous biomedical uses of these nanoparticles. In this review, we discuss the most recent advances in silver chalcogenide nanoparticle use in areas such as bio-imaging, theranostics, and biosensors. Moreover, we examine the advances in synthetic approaches for these nanoparticles, which include aqueous and organic syntheses routes. Finally, we discuss the advantages and current limitations in the use of silver chalcogenides for different biomedical applications and their potential for advancement and expansions in use.