Integration-mediated prediction enrichment of quantitative model for Hsp90 inhibitors as anti-cancer agents: 3D-QSAR study

The present study describes a systematic 3D-QSAR study consisting of pharmacophore modeling, docking, and integration of ligand-based and structure-based drug design approaches, applied on a dataset of 72 Hsp90 inhibitors as anti-cancer agents. The best pharmacophore model, with one H-bond donor (HBD), one H-bond acceptor (HBA), one hydrophobic_aromatic (Hy_Ar), and two hydrophobic_aliphatic (Hy_Al) features, was developed using the Catalyst/HypoGen algorithm on a training set of 35 compounds. The model was further validated using test set, external set, Fisher’s randomization method, and ability of the pharmacophoric features to complement the active site amino acids. Docking analysis was performed using Hsp90 chaperone (PDB-Id: 1uyf) along with water molecules reported to be crucial for binding and catalysis (Sgobba et al. ChemMedChem 4:1399–1409, 2009). Furthermore, an integration of the ligand-based as well as structure-based drug design approaches was done leading to the integrated model, which was found to be superior over the best pharmacophore model in terms of its predictive ability on internal [integrated model 2: R _(train) = 0.954, R _(test) = 0.888; Hypo-01: R _(train) = 0.912 and R _(test) = 0.819] as well as on external data set [integrated model 2: R _(ext.set) = 0.801; Hypo-01: R _(ext.set) = 0.604].     

Raman Spectroscopy of Formamidinium-Based Lead Mixed-Halide Perovskite Bulk Crystals

In recent years, there has been an impressively fast technological progress in the development of highly efficient lead halide perovskite solar cells. Nonetheless, the stability of perovskite films and associated solar cells remains a source of uncertainty and necessitates sophisticated characterization techniques. Here, we report low- to mid-frequency resonant Raman spectra of formamidinium-based lead mixed-halide perovskites. The assignment of the different Raman lines in the measured spectra is assisted by DFT simulations of the Raman spectra of suitable periodic model systems. An important result of this work is that both experiment and theory point to an increase of the stability of the perovskite structure with increasing chloride doping concentration. In the Raman spectra, this is reflected by the appearance of new lines due to the formation of hydrogen bonds. Thus, higher chloride doping results in less torsional motion and lower asymmetric bending contributing to higher stability. This study yields a solid basis for the interpretation of the Raman spectra of formamidinium-based mixed-halide perovskites, furthering the understanding of the properties of these materials, which is essential for their full exploitation in solar cells.     

Emerging Strategies in Stimuli-Responsive Silk Architectures

The utilization of implantable devices beseeches highly invasive surgeries considering the adversaries in the insertion of large, impliable devices through the body channels, which necessitate the development of implantable devices using biocompatible shape memory polymers. Silk displays prodigious heterogeneity in its genetic structure and physical properties in accordance with the spinning and storage process, where proteins undergo folding and unfolding. The stimuli-responsive nature of silk can be explained with the help of the structural morphology and composition of the material, where the hydrogen bonds in β-sheet domains and amorphous region act as switch points and net points, respectively. This review provides a primary attempt to enswathe all the literature available to date on the stimuli-responsive nature of silk and silk-based materials as a natural and biodegradable alternative for commercially used synthetic shape memory materials taking their elastomeric nature and reduction in glass transition temperature into account. Further constitutive model using the continuum approach has been utilized to explain the anisotropic elasticity damping effect and plastic deformation based on the α-helix chains, β-sheets, and β-spiral structures. The practicability to develop biomedical devices such as patient-specific-injectable scaffolds, drug carriers, and artificial muscles has been encompassed in this article.