SBA15-Fluconazole as a Protective Approach Against Mild Steel Corrosion: Synthesis, Characterization, and Computational Studies

Quartz Crystal Microbalance Application and In Silico Studies to Characterize the Interaction of Bovine Serum Albumin with Plasma Polymerized Pyrrole Surfaces: Implications for the Development of Biomaterials

Plasma polymerized pyrrole/iodine (PPPy/I) microparticles and bovine serum albumin (BSA) protein have shown interesting results in experimental models for the treatment of traumatic spinal cord injury. By studying the interaction between BSA and PPPy/I by a quartz crystal microbalance (QCM) and docking, we obtained important results to elucidate possible cellular interactions and promote the use of these polymers as biomaterials. These measurements were also used to characterize the adsorption process using an equilibrium constant. In addition, atomic force microscopy (AFM) was used to obtain images of the QCM surface sensors before and after BSA adsorption. Furthermore, we carried out molecular dynamics simulations and molecular docking to characterize the molecular recognition between BSA and the previously reported PPPy/I structure. For this study, we used two combinatorial models that have not been tested. Thus, we could determine the electrostatic (ΔGele) and nonelectrostatic (ΔGnonelec) components of the free binding energy (ΔGb). We demonstrated that BSA is adsorbed on PPPy/I with an adsorption constant of K = 24.35 μ-1 indicating high affinity. This observation combined with molecular docking and binding free energy calculations showed that the interaction between BSA and both combinatorial models of the PPPy structure is spontaneous.

Binding of Two Tetrasulfophthalocyanines (Fe(III) and Metal-Free) to Lysozyme: Fluorescence Spectroscopic and Computational Approach

The interactions between tetrasulfophthalocyanines and lysozyme were studied using fluorescence spectroscopic and computational analyses. Lysozyme has been found to be widely studied as an anticancer agent, however, there are few reports of its interaction with phthalocyanines. Fe(III) tetrasulfophthalocyanine (FeTSPc) and free base tetrasulfophthalocyanine (TSPc) used in this study, were synthesized by our research group. Experimental results suggested that the metalled complex FeTSPc has a much higher affinity than TSPc. The binding stoichiometry between each tetrasulfophthalocyanine and lysozyme was 1:1. Stern-Volmer analysis suggested that the fluorescence quenching proceedes through a static process. Binding thermodynamics (ΔG, ΔH and ΔS) confirmed that mainly hydrogen bonds, van der Waals, and electrostatic forces are responsible for the binding process. We carried out molecular dynamics simulations, molecular docking, and binding energy calculations. Molecular dynamics simulations yielded the most populated cluster of lysozyme structures, and a representative structure from this cluster was used for the docking studies with these phthalocyanines. 1000 poses were generated for each ligand. The strudtures of the resulting complexes revealed that Arg 73 and Arg 112 are important for the binding affinity of the tetrasulfophthalocyanines, generating mainly an electrostatic favorable environment for the SO3- groups. In addition, hydrophobic contacts were involved with Trp 62, Trp 63 and Trp 108, explaining the fluorescence quenching observed experimentally. Binding energies were determined for these models, confirming that the interactions with lysozyme were more favorable for FeTSPc compared to TSPc. The understanding of the molecular mechanisms is relevant to characterize the nature of tetrasulfophthalocyanines in photodynamic therapy.