Waterborne pathogens are a major public health concern, driving disease transmission and persistent contamination of water resources. Photodynamic inactivation (PDI) using immobilized photosensitizers is a promising approach for microbial control. Here, Fe3O4 magnetic nanoparticles (MNP) covalently functionalized with 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin and further modified with polyethylenimine (MNP-PEI) or spermine (MNP-SPM) were synthesized and evaluated as photodynamic antimicrobial materials. Fourier-transform infrared spectroscopy and transmission electron microscopy confirmed successful functionalization and particle sizes of approximately 14 nm. UV-visible and fluorescence spectroscopy showed the characteristic photophysical properties of the porphyrin chromophore, with fluorescence quantum yields of 0.02 and 0.03 for MNP-PEI and MNP-SPM, respectively. Both conjugates generated singlet molecular oxygen and promoted superoxide anion radical formation under irradiation. In PDI assays against Staphylococcus aureus suspensions, both materials exhibited strong antibacterial activity, with MNP-PEI achieving complete eradication after 30 min of white-light exposure. The photoinactivation efficiency was retained over three consecutive reuse cycles. In a circulating-flow reactor simulating water treatment conditions, bacterial inactivation exceeded 3.8 log (99.98%) after 30 min of irradiation. These results demonstrate the potential of MNP-PEI and MNP-SPM as efficient, reusable photodynamic agents for water disinfection in batch and continuous-flow systems.

Porphyrin-based photosensitizers have attracted considerable attention for photodynamic applications due to their ability to generate reactive oxygen species upon light irradiation. However, the development of stable and efficient photosensitizing systems remains an important challenge. In this work, a conjugated porphyrin polymer was developed through the oxidative polymerization of carbazolyl substituents incorporated into a 5,15-bis [4-(9-carbazolyl)phenyl]-10,20-bis(pentafluorophenyl)porphyrin (TPPF₁₀CBZ). The resulting polymer, P-TPPF₁₀CBZ, was characterized by spectroscopic and photophysical techniques to evaluate its structural and optical properties. Its ability to generate singlet oxygen and its photostability were also investigated, providing insights into its potential as a robust porphyrin-based photosensitizer for future photodynamic applications.

Different approaches were evaluated to obtain 5,15-bis [4-(N,N-diphenyl)aminophenyl]-10,20-bis(pentafluorophenyl)porphyrin and 5,15-bis [4-(9-carbazolyl)phenyl]-10,20-bis(pentafluorophenyl)porphyrin. First, the reaction of 5-pentafluorophenyldypyrromethane with the corresponding benzaldehyde catalyzed by boron trifluoride diethyl etherate in dichloromethane led to a high level of scrambling that produced a mixture of porphyrins. These products involve ABAB (3%), A₃B (15%), and A₄ (4%) symmetries, where A represents a pentafluorophenyl group. These porphyrins have similar polarities and they are very difficult to separate by column chromatography. Therefore, the reagents were changed to pentafluorobenzaldehyde and dipyrromethane. When a 0.5:1 molar ratio was used, A₄ porphyrin was not obtained, and the main products were ABAB (19%) and A₃B (6%). Therefore, condensation of a dipyrromethane with pentafluorobenzaldehyde provides a general method for the rational synthesis of ABAB-porphyrins in good yield with lower scrambling.