Molecular and biological activities of metal oxide-modified bioactive glass

Abstract

Bioactive glass (BG) was prepared by sol–gel method following the composition 60-($$x$$ x ) SiO2.34CaO.6P2O5, where x = 10 (FeO, CuO, ZnO or GeO). Samples were then studied with FTIR. Biological activities of the studied samples were processed with antibacterial test. Model molecules for different glass compositions were built and calculated with density functional theory at B3LYP/6-31 g(d) level. Some important parameters such as total dipole moment (TDM), HOMO/LUMO band gap energy (ΔE), and molecular electrostatic potential beside infrared spectra were calculated. Modeling data indicated that P4O10 vibrational characteristics are enhanced by the addition of SiO2.CaO due to electron rush resonating along whole crystal. FTIR results confirmed that the addition of ZnO to P4O10.SiO2.CaO significantly impacted the vibrational characteristics, unlike the other alternatives CuO, FeO and GeO that caused a smaller change in spectral indexing. The obtained values of TDM and ΔE indicated that P4O10.SiO2.CaO doped with ZnO is the most reactive composition. All the prepared BG composites showed antibacterial activity against three different pathogenic bacterial strains, with ZnO-doped BG demonstrating the highest antibacterial activity, confirming the molecular modeling calculations.

Effect of alkali metals on physical and spectroscopic properties of cellulose

“…The MESP map is a very useful color-coded three-dimensional map that is often used to predict the electron density distribution and to identify the possible sites of electrophilic and nucleophilic attacks 85 . The colors in an MESP map of a given molecule are arranged in a representative order from highest to lowest electron density as red > orange > yellow > green > blue, such that the red color indicates the highest electron density, thus lowest electrostatic potential, while blue represents the highest electrostatic potential 86 . Figures 8 , 9 and 10 show the MESP maps of cellulose and cellulose-Li, cellulose-Na, and cellulose-K, respectively.…”

“…The TDM is another important physical property of a molecule, since the dipole moments show high sensitivity even to small errors, thus considered an effective check for the efficiency of calculations, and in describing electron density distribution 87 . TDM is also an important descriptor of the reactivity and the effects of impurity atoms on the system, and it has been reported in several studies that it is closely related to reactivity, such that higher TDM reflects higher reactivity 86 – 88 . In addition, ΔE which is the difference between HOMO and LUMO is also considered an efficient indicator of the reactivity and chemical stability of the molecule 86 , 88 .…”

“…TDM is also an important descriptor of the reactivity and the effects of impurity atoms on the system, and it has been reported in several studies that it is closely related to reactivity, such that higher TDM reflects higher reactivity 86 – 88 . In addition, ΔE which is the difference between HOMO and LUMO is also considered an efficient indicator of the reactivity and chemical stability of the molecule 86 , 88 .…”

“…Aided by different methods and numerous levels of theory, molecular modeling has proven to be a very valuable computational approach to study different systems and classes of materials at the electronic and atomistic levels to investigate their electronic, structural and thermodynamic properties, serving as a guide or a complementary approach to the experimental methods 43 , 44 . Using molecular modeling, it is also possible to theoretically compute infrared, Raman and NMR spectra with high accuracy and considerable agreement with the experimental ones 45 , 46 . Density functional theory (DFT) using B3LYP-D3BJ function coupled with the 6-31g(d) basis set was used to quantify the stability of cellulose II nanocrystals 47 .…”

A redox-responsive macrocycle based on the crown ether C7Te for enhanced bacterial inhibition

“…8 Prolonged and excessive exposure to chemical disinfectants has also led to decreased treatment effectiveness and substantial economic losses. 9–12 Biofilm formation is a mechanism that grants microorganisms resistance to disinfectants. Rather than existing as free-floating entities, most microorganisms attach to surfaces or substrates and establish sessile communities known as biofilms.…”