Chemical binding

About: Chemical binding is a research topic. Over the lifetime, 1822 publications have been published within this topic receiving 52516 citations.

Direct Evidence of Covalent Immobilisation of Microperoxidase‐11 on Plasma Polymer Surfaces

Abstract: The question of whether immobilised proteins are bound covalently on plasma activated or deposited polymers has been a challenge for almost 30 years, as there has been no directly evidence to conclude unambiguously. In this paper, we report evidence that a chemical binding reaction occurred during immobilisation of microperoxidase-11 (MP-11) proteins on plasma polymer surfaces. Untreated polymer surfaces were not resistant to detergent cleaning and did not show any increase of S 2p component after protein immobilisation, whilst all plasma-deposited surfaces showed large amounts of immobilised MP-11 proteins after detergent cleaning. We conclude that the MP-11 protein had a chemical binding reaction thorough its cysteine residues with the plasma polymer surfaces.

Zinc-Calcium-Fluoride Bioglass-Based Innovative Multifunctional Dental Adhesive with Thick Adhesive Resin Film Thickness.

Abstract: Apart from producing high bond strength to tooth enamel and dentin, a dental adhesive with biotherapeutic potential is clinically desirable, aiming to further improve tooth restoration longevity. In this laboratory study, an experimental two-step universal adhesive, referred to as Exp_2UA, applicable in both the etch-and-rinse (E&R) and self-etch (SE) modes and combining a primer, containing 10-methacryloyloxydecyldihydrogen phosphate as a functional monomer with chemical binding potential to hydroxyapatite, with a bioglass-containing hydrophobic adhesive resin, was multifactorially investigated. In addition to primary property assessment, including measurement of bond strength, water sorption, solubility, and polymerization efficiency, the resultant adhesive-dentin interface was characterized by transmission electron microscopy (TEM), the filler composition was analyzed by energy-dispersive X-ray spectroscopy, and the bioactive potential of the adhesive was estimated by measuring the long-term ion release and assessing its antienzymatic and antibacterial potential. Four representative commercial adhesives were used as reference/controls. Application in both the E&R and SE modes resulted in a durable bonding performance to dentin, as evidenced by favorable 1 year aged bond strength data and a tight interfacial ultrastructure that, as examined by TEM, remained ultramorphologically unaltered upon 1 year of water storage aging. TEM revealed a 20 μm thick hydrophobic adhesive layer with a homogeneous bioglass filler distribution. Adequate polymerization conversion resulted in extremely low water sorption and solubility. In situ zymography revealed reduced endogenous proteolytic activity, while Streptococcus mutans biofilm formation was inhibited. In conclusion, the three-/two-step E&R/SE Exp_2UA combines the high bonding potential and bond degradation resistance with long-term ion release, rendering the adhesive antienzymatic and antibacterial potential.

Theoretical Study of Chemical Binding of Noble Gas Atom and Transition Metal Complexes: Ng–NiCO, Ng–NiN2, Ng–CoCO (Ng = He–Xe)

Abstract: Ab initio multireference and coupled cluster methods (MR-SDCI(+Q), CASPT2, CCSD(T)) and density functional theory methods (B3LYP, MPWPW91) have been applied to examine geometrical structures and vibrational frequencies of noble gas (Ng) – transition metal compounds, Ng–NiCO, Ng–NiN2, and Ng–CoCO (Ng = He, Ne, Ar, Kr, Xe). It is shown that the respective compounds can have a larger binding energy than a typical van der Waals interaction energy. The binding mechanism is explained by a partial electron transfer from a noble gas atom to the low-lying 4s and 3d vacant orbitals of the transition metal atom. Theoretical calculations show that the binding of noble gas atom results in a large shift of the bending frequency: 361.1 cm−1 (NiCO) to 403.5 cm−1 (Ar–NiCO); 308.5 cm−1 (NiN2) to 354.8 cm−1 (Ar–NiN2); 373.0 cm−1 (CoCO) to 422.6 cm−1 (Ar–CoCO). The corresponding experimental frequencies determined in solid argon are 409.1 cm−1 (NiCO), 357.0 cm−1 (NiN2), and 424.9 cm−1 (CoCO), which are much closer to the corresponding frequency of Ar–NiCO, Ar–NiN2, and Ar–CoCO, respectively.

Thermal Stability of RuO2 Thin Films and Effects of Annealing Ambient on Their Reduction Process.

Abstract: RuO2 films prepared by reactive sputtering were annealed in air and vacuum and the changes of their crystal structure, chemical binding state and resistivity were studied. In air, the RuO2 films maintain a rutile structure below 800°C. Crystal grain growth was found above 600°C and the minimum resistivity of 46 µΩcm was obtained at 800°C. The vacuum annealing was conducted with two types of annealing systems, one using an oil diffusion pump and the other using a turbomolecular pump as the main pump. The RuO2 films annealed in the system using the turbomolecular pump were not reduced below 500°C, however, the surface of the films was reduced as low as 200°C in the system using the oil diffusion pump. The difference in the reduction processes was examined on the basis of the thermodynamics of RuO2 and the influence of reducing residual gases in vacuum.

Extremely Long Cu···O Contact as a Possible Pathway for Magnetic Interactions in Na2Cu(CO3)2

Abstract: Chemical binding in a mixed copper sodium carbonate Na2Cu(CO3)2, a layered material showing ferromagnetic intralayer exchange and weak antiferromagnetic interlayer coupling, was examined within the topological analysis of experimental (from high-resolution X-ray diffraction) and theoretical (from periodic quantum chemical calculations) electron density functions in its crystal. Together with modeling of a superexchange pathway within the LSDA and DFT+U approach, the results obtained reveal a very weak Cu···O interaction (0.5 kcal/mol worth) between the copper–carbonate layers that is nevertheless stabilizing (bonding) and may serve as a possible pathway for antiferromagnetic interactions.