Strategic development of nextgeneration Fe iii complex functionalized gold nanoparticles toward targeted photochemotherapeutic applications

Abstract

The use of photo-activated iron(III)-phenolate complexes for light-assisted cytotoxicity in cancer therapy highlights their importance in modern medical research. Using LMCT transitions, these complexes provide a way to regulate cytotoxicity using light as a temporal control, reducing the systemic side effects linked to conventional treatment methods. Nevertheless, the practical use of iron(III)-phenolate complexes encounters obstacles because of the spectral constraints of LMCT transitions, usually falling within the 450-600 nm range. Recent literature has emphasized the possibility of achieving a red shift in surface plasmon resonance (SPR) bands by surface functionalizing gold nanoparticles with metal complexes or ligands to address this limitation. This phenomenon, especially noticeable in metal complexes in contrast to organic ligands, indicates an electronic effect that impacts the redshift. Research suggests that modifying metal complexes or ligands on gold nanoparticles results in a shift of the SPR bands towards the red region. This shift is more pronounced in metal complexes compared to organic ligands. Therefore, I speculate that an electronic effect is likely causing the redshift. For my research, I have synthesized three iron(III) pheonalto/carboxylato complexes with different electron densities over the metal center and attached them to gold nanoparticles. Surprisingly, I discovered that increasing the electron density around the metal center led to a significant redshift despite the nanoparticles being of similar size. Upon further investigation into the theoretical aspect of the nanoconjugate, it was discovered that there is an electron transfer from the metal center to the surface of the gold nanoparticles. Upon further investigation of the photophysical properties of the nanoconjugates, it was discovered that the iron(II) complex-nanoconjugate (Feand#884;and#884;atAuNPs) showed the most significant redshift.