How strong are Ca2+–heparin and Zn2+–heparin interactions?

Clot activators and anticoagulant additives for blood collection. A critical review on behalf of COLABIOCLI WG-PRE-LATAM

In the clinical laboratory, knowledge of and the correct use of clot activators and anticoagulant additives are critical to preserve and maintain samples in optimal conditions prior to analysis. In 2017, the Latin America Confederation of Clinical Biochemistry (COLABIOCLI) commissioned the Latin American Working Group for Preanalytical Phase (WG-PRE-LATAM) to study preanalytical variability and establish guidelines for preanalytical procedures to be applied by clinical laboratories and health care professionals. The aim of this critical review, on behalf of COLABIOCLI WG-PRE-LATAM, is to provide information to understand the mechanisms of the interactions and reactions that occur between blood and clot activators and anticoagulant additives inside evacuated tubes used for laboratory testing. Clot activators - glass, silica, kaolin, bentonite, and diatomaceous earth - work by surface dependent mechanism whereas extrinsic biomolecules - thrombin, snake venoms, ellagic acid, and thromboplastin - start in vitro coagulation when added to blood. Few manufacturers of evacuated tubes state the type and concentration of clot activators used in their products. With respect to anticoagulant additives, sodium citrate and oxalate complex free calcium and ethylenediaminetetraacetic acid chelates calcium. Heparin potentiates antithrombin and hirudin binds to active thrombin, inactivating the thrombin irreversibly. Blood collection tubes have improved continually over the years, from the glass tubes containing clot activators or anticoagulant additives that were prepared by laboratory personnel to the current standardized evacuated systems that permit more precise blood/additive ratios. Each clot activator and anticoagulant additive demonstrates specific functionality, and both manufacturers of tubes and laboratory professional strive to provide suitable interference-free sample matrices for laboratory testing. Both manufacturers of in vitro diagnostic devices and laboratory professionals need to understand all aspects of venous blood sampling so that they do not underestimate the impact of tube additives on laboratory testing.

Synthesis and Characterization of Functionalized Nanosilica for Zinc Ion Mitigation; Experimental and Computational Investigations

Zinc is an essential trace metal and its concentration above 4ppm reduces the aesthetic value of water. This study explores the possibility of using functionalized nanohybrids as Zn(II) ion scavengers from aqueous solution. Functionalized nanohybrids were synthesized by the attachment of thiosemicarbazide to silica. The material was characterized by TGA, SEM, FTIR, EDX, and BET analysis, which revealed ligand bonding to silica. The functionalized silica was employed as Zn(II) ion extractant in batch experiments and removed about 94.5% of the Zn(II) ions at pH 7, near zero point charge (6.5) in 30 min. Kinetics investigations revealed that zinc adsorption follows an intra particle diffusion mechanism and first-order kinetics (K = 0.1020 min⁻¹). The data were fitted to Freundlich, Dubinin–Radushkevich, and Langmuir models and useful ion exchange parameters were determined. The impact of co-existing ions on Zn(II) ion sequestration was also studied and it was found that the adsorbent can be used for selective removal of zinc with various ions in the matrix. Quantum mechanical investigations revealed that the Zn(II) ion adsorption on ZnBS1 is more favorable, having higher binding energy (BE) (−178.1 kcal/mol) and ∆H (−169.8), and making tridentate complex with the N and S sites of the chelating ligand. The negative ∆G and BE values suggest highly spontaneous Zn(II) adsorption on the modified silica even at low temperatures.