Zirconium

Abstract

The action of Zirconium (Zr) on biological systems presents an enigma. It is ubiquitous, being present in nature in amounts higher than most trace elements. It is taken up by plants from soil and water and accumulated in certain tissues. The entry into animal systems in vivo is related to the mode of exposure and the concentration in the surrounding environment. Retention is initially in soft tissues and then slowly in the bone. The metal is able to cross the blood brain-barrier and is deposited in the brain and the placental barrier to enter milk. The daily human uptake has been known to be as high as 125 mg. The level of toxicity has been found to be moderately low, both in histological and cytological studies. The toxic effects induced by very high concentrations are nonspecific in nature. Despite the presence and retention in relatively high quantities in biological systems, Zr has not yet been associated with any specific metabolic function. Very little information is available about its interaction with the compounds of the genetical systems, such as nucleic acids. Apparently, the metal is neither an essential nor toxic element in the conventional sense. However, the increasing exposure to this element through its increasing use in new materials and following radioactive fallout, has increased the importance of the study of its effects on living organisms. The tetravalent nature of the ionic state and the high stability of the compounds formed are important factors that need to be considered, as also the accumulation of this element in the brain, reminiscent of the relationship between Al3+ and Alzheimer's disease.

In vivo biodistribution and accumulation of 89Zr in mice

“…In the present case, when Zr is chelated, the radioactivity is significantly cleared from the mice body. The clearance of [ 89 Zr]Zr-oxalate (bidentate chelator [18]) is relevant as it resembles an unstable complex at physiological pH, in comparison to [ 89 Zr]Zr-citrate (tridentate chelator, moderately stable [19]) or [ 89 Zr]Zr-DFO (hexadentate chelator, stable complexes [20]). In addition, the biodistribution of [ 89 Zr]Zr-oxalate is characteristic of Zr itself with a strong affinity for the bones and the joints (see PET image, Fig.…”

“…Zr 4+ forms an insoluble salt with the phosphate and precipitates in water [2, 19, 21] as observed in Fig. 1.C in which all the activity is concentrated at the origin point of the electrophoreses.…”

ZrO(HPO4)1−x(FMN)x: Quick and Easy Synthesis of a Nanoscale Luminescent Biomarker

“…Chemical synthesis should be as easy as possible and potentially provide reliable access to large quantities. The system ZrO-(HPO 4 ) 1Àx (FMN) x (x = 0-1) and its formal constituents ZrO 2+ , HPO 4 2À , FMN 2À (FMN: flavin mononucleotide, a derivative of vitamin B 2 , Figure 1) [11] attracted our attention for several reasons: 1) The very low solubility, which facilitates nucleation and growth of nanoparticles; [12] 2) The chemical inertness of zirconium phosphates; 3) All the constituents are known for their biocompatibility (e.g., lethal intake of ZrCl 4 > 1 gkg À1 ); [13] 4) Depending on the chemical composition, the dye concentration can be tuned from very low (< 1 mol %) up to molar amounts. The underlying concept of a luminescent hybrid material that is formally composed of an inorganic cation and an anionic fluorescent dye has not been reported previously.…”

Tuning Zr(IV)-assisted peptide hydrolysis at near-neutral pH

“…6 [4].) In addition, Zr(IV) possesses low cellular toxicity [5], enhanced Lewis acid strength, and rapid-ligand exchange kinetics [6], a requirement for efficient catalytic turnover. At pH values above 5.0-5.2, Zr(IV) forms insoluble gels and precipitates [7].…”