New phthalonitrile/metal phthalocyanine-gold nanoparticle conjugates for biological applications

The emergence of nanoscience and its effect on the development of diverse scientific fields, particularly materials chemistry, are well known today. In this study, a new di-substituted phthalonitrile derivative, namely 4,5-bis((4-(dimethylamino)phenyl)ethynyl)phthalonitrile (1), and its octa-substituted metal phthalocyanines {M = Co (2), Zn (3)} were prepared. All the newly synthesized compounds were characterized using a number of spectroscopic approaches, including FT-IR, mass, NMR, and UV-vis spectroscopy. The resultant compounds modified the surface of the gold nanoparticles (NG-1-3). Characterization of the newly synthesized conjugates was carried out by transmission electron microscopy. The antioxidant activity of compounds 1-3, NG-1-3, and NG was evaluated using the DPPH scavenging process and the highest radical scavenging activity was obtained with compounds 1, NG-1, 2, and NG-2 (100%). The antimicrobial activity of compounds 1-3, NG-1-3, and NG was studied using a microdilution assay and the most effective antimicrobial activity was obtained for NG-3 against all the tested microorganisms. The newly synthesized compounds demonstrated high DNA cleavage activity. Compounds 1-3, NG-1-3, and NG significantly inhibited the microbial cell viability of E. coli and exhibited perfect antimicrobial photodynamic therapeutic activity with 100% inhibition after 20 min LED irradiation. Besides, the biofilm inhibition activity of compounds 1-3, NG-1-3, and NG on the growth of S. aureus and P. aeruginosa were examined and compounds 1-3 and NG-1-3, especially NG-1-3, displayed high biofilm inhibition activities.