Multifunctional biocompatible Janus nanostructures for biomedical applications

Janus-shaped nanostructures, a promising structure type named after the Roman god with two faces, have received considerable attention owing to their multifunctional characteristics and synergistic effects. Janus nanoparticles (JNPs) should not only exhibit reinforced properties but also present diversified aptitudes to be instantaneously utilizable in materials science and biomedicine applications. Many reports have been available on the facile synthesis and potential application of JNPs over the past few years. In this review article, we intend to emphasize the latest improvement of JNPs for the field of cancer theranostics. Facile synthesis methods of Janus colloidal nanostructures, their significant properties, biocompatibility, and interesting implementations in biomedical applications are summarized and discussed. Selected studies clearly demonstrate that the surface of these asymmetrical JNPs is perfectly appropriate for the conjugation of multiple components onto a single-particle system. Hence, multiple target ligands and drugs are attached on the diverse surfaces of the JNPs according to the host receptor. Therefore, these types of multifunctional JNPs will enable enhanced diagnosis by early imaging, effective tumor cell targeting, drug delivery, and therapy. Key challenges in fabrication and biocompatibility of JNPs for biomedical applications are also discussed.