Antibacterial Nanoparticles with Natural Photosensitizers Extracted from Spinach Leaves

Pavel Ludačka; Pavel Kubát; Zuzana Bosáková; Jiří Mosinger

doi:10.1021/acsomega.1c06229

Antibacterial Nanoparticles with Natural Photosensitizers Extracted from Spinach Leaves

ACS Omega. 2021 Dec 17;7(1):1505-1513. doi: 10.1021/acsomega.1c06229. eCollection 2022 Jan 11.

Authors

Pavel Ludačka¹, Pavel Kubát², Zuzana Bosáková¹, Jiří Mosinger¹

Affiliations

¹ Faculty of Science, Charles University, 2030 Hlavova, 128 43 Prague 2, Czech Republic.
² J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic.

Abstract

We prepared antibacterial polystyrene nanoparticles (NPs) with natural photosensitizers from chlorophyll (Chl) extract via a simple nanoprecipitation method using the same solvent for dissolution of the polystyrene matrix and extraction of Chls from spinach leaves. A high photo-oxidation and antibacterial effect was demonstrated on Escherichia coli and was based on the photogeneration of singlet oxygen O₂(¹Δ_g), which was directly monitored by NIR luminescence measurements and indirectly verified using a chemical trap. The photoactivity of NPs was triggered by visible light, with enhanced red absorption by Chls. To reduce the quenching effect of carotenoids (β-carotene, lutein, etc.) in the Chl extract, diluted and/or preirradiated samples, in which the photo-oxidized carotenoids lose their quenching effect, were used for preparation of the NPs. For enhanced photo-oxidation and antibacterial effects, a sulfonated polystyrene matrix was used for preparation of a stable dispersion of sulfonated NPs, with the quenching effect of carotenoids being suppressed.