Ligand-Tuning of the Stability of Pd(II) Conjugates with Cyanocobalamin

Abstract

Besides the well-known functions performed by vitamin B12 (CblCN) in biochemical processes of the human body, an increasing interest has been raised by the possibility of its use as a transmembrane drug carrier, capable, among others, of enhancing the accumulation of inorganic cytostatics in cancer cells. The present study was aimed at determining the possibility of the formation of CblCN conjugates with Pd(II) complexes. A key aspect was their stability, which we attempted to tune by appropriate choice of ligands. Syntheses, spectroscopic analysis of postreaction systems and kinetic investigations of conjugate formation reactions, have been complemented by DFT modelling. The obtained results showed that ligand charge, geometry and electron affinity may have a significant impact on carrier binding and release leading to the activation of the Pd(II) complex. This provides a rationale to expect that with appropriate composition of the coordination sphere, it will be possible to extend the spectrum of less toxic inorganic chemotherapeutics.

A biophysical study of the interactions of palladium(ii), platinum(ii) and gold(iii) complexes of aminopyridyl-2,2′-bipyridine ligands with RNAs and other nucleic acid structures

“…However, the much greater lability of Pd( ii ) complexes compared to Pt( ii ) analogues is well documented and supports the possibility of a rapid ligand release in solution. 63 Noteworthily, [Pd(H 2 L2)]Cl 2 differs from the other Pd-containing analogue [Pd(H 2 L1)]Cl 2 only by the presence of the two methyl groups on the pyridyl moieties of the ligand. Probably, this structural difference is responsible for the different reactivity patterns of the two compounds and for the greater propensity of [Pd(H 2 L2)]Cl 2 to lose the organic ligand.…”

Dual (pH- and ROS-) Responsive Antibacterial MXene-Based Nanocarrier for Drug Delivery

“…Furthermore, the release exponent (n) values were 0.271, 0.096, 0.143, 0.159, 0.209, and 0.201 at pH 5.5, pH 7.4, pH 7.4 + H 2 O 2 , pH 7.4 + GSH, pH 5.5 + H 2 O 2 , and pH 5.5 + GSH, respectively. These results show that the DOX release exponent values are less than 0.43 in different release media, which indicates that the release kinetics from MXene-Se-DOX nanosheets followed the Fickian diffusion mechanism [ 50 , 51 , 52 ]. These results indicate that Fickian diffusion plays a major role in the release process.…”