Current trends in pyrrole and porphyrin-derived nanoscale materials for biomedical applications

This article is written to provide an up-to-date review of pyrrole-based biomedical materials. Porphyrins and other tetrapyrrolic molecules possess unique magnetic, optical and other photophysical properties that make them useful for bioimaging and therapy. This review touches briefly on some of the synthetic strategies to obtain porphyrin- and tetrapyrrole-based nanoparticles, as well as the variety of applications in which crosslinked, self-assembled, porphyrin-coated and other nanoparticles are utilized. We explore examples of these nanoparticles' applications in photothermal therapy, drug delivery, photodynamic therapy, stimuli response, fluorescence imaging, photoacoustic imaging, magnetic resonance imaging, computed tomography and positron emission tomography. We anticipate that this review will provide a comprehensive summary of pyrrole-derived nanoparticles and provide a guideline for their further development. Lay abstract Nanoparticles are very small particles that are less than a fraction of the thickness of a strand of hair. These particles can be used as contrast agents (e.g., for use in a computerized axial tomography [CAT] scan) or to help deliver treatment directly to a tumor. This is a review article that explores the biomedical applications of nanoparticles formed from chemicals known as tetrapyrroles, that are often found in nature. Tetrapyrroles have many characteristics that allow them to provide good image contrast and therapeutic benefits. In this review, we discuss some characteristics of tetrapyrroles and examples of tetrapyrrole nanoparticles in a variety of biomedical applications.