Biological activities of metallic nanostructures functionalized with hexadeca-substituted copper(ii) and cobalt(ii) phthalocyanines

Abstract

A novel phthalonitrile derivative (a) containing three functional groups (hexyl, aminated ester, phenoxy) was synthesized and subsequently cyclotetramerized in the presence of the corresponding metal chloride salts to obtain hexadeca-substituted metal {M = Cu(II) and Co(II)} phthalocyanines (b and c). The water-soluble phthalocyanines (d and e) were prepared by treating the newly synthesized complexes (b and c) with methyl iodide. Moreover, gold nanoparticles (1) and silver nanoparticles (2) were prepared, and their surfaces were modified with quaternary phthalocyanines (d and e). The biological properties of both unmodified (1 and 2) and functionalized nanostructures (1d, 1e, 2d, and 2e) were extensively studied. All nanomaterials exhibited moderate antioxidant activity. Nanoconjugate (2e) at 100 mg L⁻¹ displayed the highest inhibitory activity (98.7%) against α-amylase. Moreover, all nanostructures cleaved DNA molecules at 100 mg L⁻¹. The MIC of nanostructures (1, 2, 1d, 1e, 2d, and 2e) ranged from 2 to 64 mg L⁻¹ for inhibiting bacterial growth. Additionally, all nanostructures (especially modified silver nanostructures) demonstrated greater biofilm inhibition activity against S. aureus compared with P. aeruginosa. Surficial modification of nanostructures with resultant phthalocyanines improved their microbial cell viability inhibition activity against E. coli, particularly after irradiation. This significant improvement in the biological activities of metallic nanoparticles suggests that, with further investigation, these new nanoconjugates could be considered promising candidates for medical nanomaterials.