Recent Advances in the Design and Sensing Applications of Hemin/Coordination Polymer-Based Nanocomposites

The fabrication of biomimetic catalysts as substituents for enzymes is of critical interest in the field due to the problems associated with the extraction, purification, and storage of enzymes in sensing applications. Of these mimetics, hemin/coordination polymer-based nanocomposites, mainly hemin/metal-organic frameworks (MOF), have been developed for various biosensing applications because of the unique properties of each component, while trying to mimic the normal biological functions of heme within the protein milieu of enzymes. This critical review first discusses the different catalytic functions of heme in the body in the form of enzyme/protein structures. The properties of hemin dimerization are then elucidated with the supposed models of hemin oxidation. After that, the progress in the fabrication of hemin/MOF nanocomposites for the sensing of diverse biological molecules is discussed. Finally, the challenges in developing this type of composites are examined as well as possible proposals for future directions to enhance the sensing performance in this field further.

The interaction of a cobalt porphyrin with cancer-associated nitrosamines

A cobalt porphyrin (CY-B) was presented, and its interaction with tobacco-specific nitrosamines (TSNAs) was investigated by UV-Vis spectroscopy and high-resolution mass spectrometry. The results revealed that the stoichiometry of the host-guest interaction was 1:2 and that the binding constant between CY-B and TSNAs was within the range of 0.78×10(8)-7.83×10(8)M(-2). The coordination strength between CY-B and TSNAs decreased in the sequence of NNN>NAB>NAT>NNK based on the binding constant. The interaction mechanism of CY-B with TSNAs involved a coordination interaction, and the π-π interaction between the porphyrin macrocycle and the aromatic frame of the TSNAs pyridines may also have been a driving force. The measured thermodynamic properties demonstrated that the reaction of CY-B with TSNAs was spontaneous and that the driving force for the interaction was a change in enthalpy. The reaction was exothermic, and an increasing temperature inhibited the interaction. The IR spectrum of the complex revealed that the NNO group of TSNAs and the metal cobalt of CY-B formed the six-coordinate complex.