Synthesis and surface characterization of new triplex polymer of Ag(I) and mixture nucleosides: cytidine and 8-bromoguanosine

Synthesis and crystal structure of a silver(I) 6-methylmercaptopurine riboside complex

Silver nitrate reacts with 6-methylmercaptopurine riboside (6-MMPR) in aqueous solution containing methanol and dimethyl sulfoxide at room temperature to give a colourless crystalline complex, namely, bis(6-methylmercaptopurine riboside-κN7)(nitrato-κ2O,O')silver(I) 2.32-hydrate, [Ag(NO3)(C11H14N4O4S)2]·2.32H2O. The crystal structure, determined from synchrotron diffraction data, shows a central AgI ion on a crystallographic twofold rotation axis, coordinated in an almost linear fashion by two 6-MMPR ligands via atom N7 (purine numbering), with the nitrate counter-ion loosely coordinated as a bidentate ligand, forming a discrete molecular complex as an approximate dihydrate. The complex and water molecules are connected in a three-dimensional network by hydrogen bonding.

Employing spatial, hybrid and amplitude roughness parameters for unveiling the surface roughness features of mineral and organic admixtures

Scanning electron microscopy (SEM) permits to evaluate the surface morphology and surface roughness of pozzolans and admixtures. The field of mineral and organic admixtures has considerable interest in using SEM. However, several challenges are encountered which hamper the precision of quantitative roughness evaluation of mineral and organic admixtures using SEM and these challenges are usually bypassed in literature. In this research, surface roughness properties of pozzolans and admixtures were analysed from six perspectives: spatial parameters, hybrid parameters, amplitude parameters, surface roughness profiles, bearing ratio curves (BRCs) and amplitude density functions (ADFs). The generated roughness characteristics provided detailed information of roughness properties of the pozzolans and admixtures in a time efficient and cost effective way, which is usually very hard to achieve using experimental works. The comparisons of the obtained roughness data for the specimens showed considerable agreement with the roughness profiles and verified the interpretation of the established roughness profiles. Using the ADFs and BRCs for evaluating heights of the roughness profiles provided significant data encapsulated in the shapes of ADFs and BRCs. Moreover, the interpretation of the transformed logarithmic profiles seemed to have nearly retained similar meanings with the conventional profiles, although their scrutiny was observed to be complex. With brand new discussions on spatial, hybrid and amplitude parameters of mineral and organic admixtures, this research is a step forward in characterisation of roughness parameters of mineral and organic admixtures. This study expands the characterisation of pozzolans and admixtures, highlighting significant parameters to be considered in the application of mineral and organic admixtures.

Synthesis, characterization, and biological activities of new conjugates of Guanosine grafted on polyvinyl alcohol, carbohydrate chitosan, and cellulose

Guanosine (GU) is a purine nucleoside that has different biological applications. This study aimed to synthesize, characterize, and enhance the biological activities of GU through its covalently grafting on polyvinyl alcohol (PVA), chitosan (CS), and cellulose (CL). In this regard, the conjugation was constructed by different linkers such as chloroacetyl chloride, 2-bromopropionyl bromide, and epichlorohydrin (EPCH). The resulted novel conjugates were characterized by FT-IR, 1H-NMR, GPC, and TGA techniques. FT-IR spectra revealed the main characteristic groups, O–H, N–H, C=O and C=N of GU moieties. Furthermore, 1H-NMR spectra showed the aromatic C–H, O–H, and N–H protons of the grafted GU moieties. Two decomposition stages of grated polymers with high thermal stability are illustrated by TGA. GU showed no antifungal activity against Aspergillus fumigatus and Candida albicans. However, its conjugates: P-1A, P-1B, P-2A, P-2B, P-3A, and P-3B displayed significant antifungal effect with inhibitory zones in the range 8–11 mm. As compared to GU group, most of GU-polymer conjugates showed significant in vivo antitumor activity against EAC-bearing mice via the reduction in total tumor volume. In summary, these conjugates are biologically active macromolecules and may act as candidate carrier systems for other applications such as drug delivery.

Analytical study to determine the optical properties of gold nanoparticles in the visible solar spectrum

In this work the optical properties of the formed gold nanoparticles, that obtained upon reducing the gold(I):6-thioguanosine hydrogel by dimethylamine borane (DMAB) have been studied. The analytical measurements to calculate the optical band gap showed a significant narrowing in the optical band gap value (E_g). Tauc plot was used to estimate the optical band gap (Eg) with the direct and indirect allowed transitions, before and after the reducing process. Narrowing the band gap is very important to increase the efficiency of the semiconductor material as it leads to absorbing in the visible region of the solar spectrum.