Synthesis of nanoparticles of cobalt protoporphyrin IX (Co(<scp>iii</scp>)PPIX NPs). Antiradical, cytotoxicity and antibacterial properties

Porphyrins, composed of a tetrapyrrolic core and various substituents, are highly valued for their photo-, catalytic, electrochemical, and biochemical properties. Protoporphyrin IX (PPIX) is a heterocyclic organic compound whose porphyrin ring enables the chelation of transition metals, resulting in metalloporphyrins with diverse biological functions. Cobalt protoporphyrin IX (Co(iii)PPIX) is known as an inducer of heme oxygenase-1 (HO-1) and has been identified as a potential photosensitiser for use in photodynamic cancer therapy. In this study, Co(iii)PPIX nanoparticles (NPs) were synthesised <i>via</i> the antisolvent method. The resulting NPs were thoroughly characterised using FTIR spectroscopy, Raman spectroscopy, UV-Vis spectroscopy, DLS, SEM, and EDX techniques. Furthermore, their biological properties were investigated, including antibacterial activity (against <i>E. coli</i>, <i>S. aureus</i>, and <i>K. pneumoniae</i>), antioxidant activity, and cytotoxicity tests on Caco-2 and L929 cell lines. The antisolvent method allowed for the synthesis of NPs with a hydrodynamic size below 300 nm, and for one sample, below 200 nm, depending on the conditions. Following synthesis, ultrafiltration (UF) was employed to purify the samples by removing particles not involved in NP formation. A comparative study was conducted between samples subjected to UF and those that were not. The results indicate that using UF led to the synthesis of smaller NPs (307.7 <i>vs.</i> 190.2 nm), differences in Raman spectra, and modified biological properties.