Herein we describe a combined experimental and in silico study of the interaction of a series of pyrazolo[1,2-a]benzo[1,2,3,4]tetrazin-3-one derivatives (PBTs) with parallel G-quadruplex (GQ) DNA aimed at correlating their previously reported anticancer activities and the stabilizing effects observed by us on c-myc oncogene promoter GQ structure. Circular dichroism (CD) melting experiments were performed to characterize the effect of the studied PBTs on the GQ thermal stability. CD measurements indicate that two out of the eight compounds under investigation induced a slight stabilizing effect (2–4 °C) on GQ depending on the nature and position of the substituents. Molecular docking results allowed us to verify the modes of interaction of the ligands with the GQ and estimate the binding affinities. The highest binding affinity was observed for ligands with the experimental melting temperatures (T_ms). However, both stabilizing and destabilizing ligands showed similar scores, whilst Molecular Dynamics (MD) simulations, performed across a wide range of temperatures on the GQ in water solution, either unliganded or complexed with two model PBT ligands with the opposite effect on the T_ms, consistently confirmed their stabilizing or destabilizing ability ascertained by CD. Clues about a relation between the reported anticancer activity of some PBTs and their ability to stabilize the GQ structure of c-myc emerged from our study. Furthermore, Molecular Dynamics simulations at high temperatures are herein proposed for the first time as a means to verify the stabilizing or destabilizing effect of ligands on the GQ, also disclosing predictive potential in GQ-targeting drug discovery.

The formation of the protein corona critically governs the biological identity of nanoparticles, but the molecular determinants of protein orientation and conformational fate remain elusive. Here, we examine the adsorption of bovine serum albumin (BSA), a prototypical dysopsonin, onto bare and amino-functionalized mesoporous silica nanoparticles (MSN and MSN-NH₂) at physiological pH. Zeta potential titrations, quartz crystal microbalance with dissipation monitoring (QCM-D), and circular dichroism (CD) spectroscopy reveal robust binding of BSA to both negatively charged MSN and positively charged MSN-NH₂. QCM-D quantification indicates enhanced adsorption on MSN-NH₂ (481 ng cm^-2) relative to that on MSN (228 ng cm^-2), consistent with attractive electrostatic interactions. Strikingly, substantial BSA adsorption also occurs on MSN, even though both species carry negative zeta potentials. This indicates orientation-dependent interactions driven by the heterogeneous charge distribution of BSA, likely involving domain III binding to the silica surface. CD spectroscopy further demonstrates that the nanoparticle surface charge dictates the BSA secondary structure: the α-helix content decreases from 60% to 25%, while β-sheet and random coil fractions increase upon adsorption to MSN-NH₂. Whereas BSA retains its native (N) conformation on MSN, it undergoes pronounced distortion toward fast (F) or elongated (E) states on MSN-NH₂. These findings establish that nanoparticle surface charge governs not only the adsorption extent but also protein orientation and conformational fate, thereby shaping protein corona formation and its downstream biological identity.

Previous studies of proton transfer phenomena in the cyclic voltammetry of gold electrodes functionalized with self-assembled monolayers of acidic thiols focused either on very low scan rates (v < 10 mV s−1 ) or relatively high scan rates (v > 100 mV s−1 ).Our investigations at intermediate scan rates (between 20 mV s−1 and 100 mV s−1 ) revealed phenomena not reported in previous studies. In particular, during the forward scan (0 V to −0.45 V vs. Ag/AgCl), the protonation peak is not observed as a single well-defined narrow feature. Instead, its shape depends on the pH of the electrolyte solution: at low pH the peak appears elongated, whereas at higher pH it remains narrow. In contrast, during the reverse scan (−0.45 V to 0 V), the shape of the deprotonation peak does not appear to be affected by the pH.This observation led us to propose a complex proton transfer mechanism, which depends both on the electrode potential and on the bulk proton concentration (pH). The broad peak indicates that dual kinetic regimes are active at mid scan rates, involving rate of protonation of the acid site by protons taken from the nearby double layer, and the rate of diffusion of protons from bulk solution.To further analyse this proposed mechanism, we conducted numerical simulations using the non-equilibrium Poisson-Nernst-Plank equation, describing ion diffusion in the presence of an applied electric field. The Poisson-Nernst-Plank model was modified to account for ion-specific finite-size Carnahan-Starling steric effects, and included the charge regulation surface reactions of protonation and deprotonation. The steric flux is significant at electrode potentials exceeding 0.2V relative to bulk. The theoretical model describes a single electrode with a time-varying bulk boundary condition that evolves in response to the deviation of the chemical potential ofions with respect to bulk electrolyte. This generates an ion flux from bulk controlled by a bulk distance parameter, which is responsible for the observed elongation in the protonation peak.