Application of structural analogs of dimercaptosuccinic acid-functionalized silica nanoparticles (DMSA-[silica]) to adsorption of mercury, cadmium, and lead

In order to gain additional insight into mercury selectivity with nano-sized DMSA-[silica], we investigated a series of ligands related to DMSA, these are: monomercaptosuccinic acid; MMSA, 2-mercapto-4-methyl-5-thiazoleacetic acid; MCT, ortho-thiosalicylic acid; o-TSA and para-thiosalicylic acid; p-TSA. The MMSA chelate is structurally similar to DMSA except that it has only one thiol group. The chelates o-TSA and p-TSA each have one thiol and one carboxylic acid group. MCT includes neutral S and N atoms in close proximity to the thiolate binding site. MCT, o-TSA and p-TSA resemble each other in having equal numbers of carboxylic acid and thiol groups and formation of amide bonds with the linker on silica is expected to eliminate the carboxylate binding sites, making thiolates the only binding sites for Hg(II), Cd(II), and Pb(II) metals ions in the nano-sized; MMSA-[silica], MCT-[silica], o-TSA-[silica], and p-TSA-[silica]. Each of the nano-sized MMSA-[silica], MCT-[silica], o-TSA-[silica], and p-TSA-[silica], show a higher preference for Hg(II) over Cd(II) and Pb(II) compared to the same free chelates in solution, respectively. In addition, there are differences in the level of metal ion chelation for each functionalized silica nanoparticle. These differences in the degree of metal chelation for each functionalized silica nanoparticles surface are explained by the difference in thiolate/carboxylate ratio upon attachment to the surface and on steric reasons based on the orientation of the thiol groups on the surface. When attached via amide bond formation, the thiolate site in o-TSA-[silica] will face towards the silica surface, while for p-TSA-[silica], the thiolate site is expected to be pointed outwards and away from the silica surface. In comparing MMSA-[silica] to DMSA-[silica], the thiolate/carboxylate ratio decreases from 2/1 in DMSA-[silica] to 1/1 in MMSA-[silica] (assuming attachment via one amide bond in each case). This effect of increasing the ratio of thiolate to carboxylate upon attachment to the surface is believed to play a role in the selectivity enhancement towards Hg(II) over Cd(II) and Pb(II).     

YOYO as a Dye to Track Penetration of LK15 DNA Complexes in Spheroids: Use and Limits

To elucidate the reasons underlying the poor penetration of non-viral vectors in tissues, relating transport properties to physico-chemical parameters of vectors may be crucial. These properties can be influenced by the presence of multiples labels that are used. Therefore utilizing a vector with minimum of labels preferably not more than one is important to studying penetration in tissues. The cell impermeant bisintercalating dye YOYO-1 was found suitable to both monitor the formation of complexes between DNA and an amphipathic peptide LK15 and, to track their penetration in HCT116 spheroids by confocal microscopy. The results revealed a limited decrease of fluorescence ascribed to the high affinity of YOYO-1 to bind DNA. The residual fluorescence of complexes can be exploited to monitor penetration into spheroids, after correction for YOYO-1 attenuation, and to revealing hyaluronidase-induced reduced binding. Hence high affinity dyes such as YOYO-1 with inefficiently quenched fluorescence may be important to establish a relation between novel medicines characteristics and penetration in tissues.     

Trapezoidal-Type Inequalities for Strongly Convex and Quasi-Convex Functions via Post-Quantum Calculus

In this paper, we establish new (p,q)κ1-integral and (p,q)κ2-integral identities. By employing these new identities, we establish new (p,q)κ1 and (p,q)κ2- trapezoidal integral-type inequalities through strongly convex and quasi-convex functions. Finally, some examples are given to illustrate the investigated results.