Synthesis, characterization, protein interaction and antibacterial activity of a lanthanum(iii) complex [La(Trp)3(OH2)2] (Trp = tryptophan) as a new precursor for synthesis of La2O2CO3 nanoparticles

Abstract

In the present study, a lanthanum(III) complex containing tryptophan amino acid was synthesized and characterized. The abovementioned complex was assayed for antibacterial activity against 21 pathogens in humans including 10 Gram-negative and 11 Gram-positive bacteria. The results showed that this complex exhibits moderate to good antibacterial activity against different bacterial strains. This complex was selected to investigate its binding to human serum albumin (HSA) by spectroscopy and molecular docking methods. The fluorescence data showed that La(III) complexes quench the fluorescence of protein by a static quenching mechanism. The binding constant (K_b), number of binding sites (n) and thermodynamic parameters were calculated, which showed that the La(III) complex binds to HSA through hydrophobic interactions with one binding site. The molecular docking results confirmed the spectroscopic results and showed that the abovementioned complex is embedded into subdomain IIA of protein. Moreover, this lanthanum(III) complex was used for the synthesis of La₂O₂CO₃ nanoparticles. The prepared nanoparticles were characterized by FT-IR, XRD, SEM and EDX analyses. The photo-catalytic activity of these nanoparticles was studied using ethidium bromide degradation under ultraviolet irradiation. The results showed that these nanoparticles are promising materials in this photo-catalytic degradation.