On the Chemical Stability of CeIV(PO4)(HPO4)0.5(H2O)0.5 in Alkaline Media

The combination of ultrasonic exposure on ceric phosphate gels with subsequent hydrothermalmicrowave treatment resulted in the formation of nanoscale NH 4 Ce 2 (PO 4 ) 3 or KCe 2 (PO 4 ) 3 phases. The sun protection factor (SPF) and protection factor against UV-A radiation (UVAPF) values for double ceric phosphates with the smallest crystallite sizes exceeded 4 and 3.5, respectively, which is much higher than the values for samples consisting of larger particles. These results are superior to previously published values for similar ceric compounds, and thus show promise for their application in sunscreens.

Section: Resultsmentioning

confidence: 93%

Ultrasonic-assisted hydrothermal synthesis of nanoscale double ceric phosphates

Ivanov,

Baranchikov,

Teplonogova

et al. 2024

“…This fact along with the similar report [21] can contribute to one of the most disputable topics of the chemistry of nanocrystalline ceria, namely its oxygen non-stoichiometry [28][29][30]. The possibility of the partial reduction of Ce(IV) during hydrothermal synthesis of crystalline cerium(IV) phosphates, as well as monazite structure formation under hydrothermal conditions, have been also discussed recently [31][32][33][34] but the exact mechanisms were not analyzed in detail and require further studies.…”

Section: Resultsmentioning

confidence: 98%

Synthesis and thermal behavior of KCe2(PO4)3, a new full-member in the AIMIV 2 (PO4)3 family

Kozlova¹,

Vasilyeva²,

Козлов³

et al. 2023

Hydrothermal treatment of nanoscale amorphous ceric phosphate gel in KOH aqueous solutions was found to result in a new KCe 2 (PO 4 ) 3 phase. The refinement of the KCe 2 (PO 4 ) 3 structure showed that it was isostructural to recently reported (NH 4 )Ce 2 (PO 4 ) 3 . For the KCe 2 (PO 4 ) 3 phase, the unit cell parameters (sp. gr. C2/c) were a = 17.3781(3) Å, b = 6.7287(1) Å, c = 7.9711(2) Å, β = 102.351(1) • , V = 910.53(4) Å3 , Z = 4. The thermal decomposition of KCe 2 (PO 4 ) 3 at 800 • C resulted in the mixture of crystalline CePO 4 and KPO 3 .

“…Note that, for cerium(IV) phosphates, the data is even more scarce, the solubility of Ce(PO 4 )(HPO 4 ) 0.5 (H 2 O) 0.5 was reported to be lower than 1 mg/l in an aqueous medium at pH 1.3 [58], while in 1 M alkaline aqueous solution, the structure of this compound was reported to degrade completely due to the hydrolysis and the formation of Ce-O-Ce bonds [59].…”

Section: Resultsmentioning

confidence: 99%

Ceric phosphates and nanocrystalline ceria: selective toxicity to melanoma cells

Kozlova¹,

Попов²,

Romanov³

et al. 2023

Nanocrystalline cerium dioxide is a promising inorganic UV filter for sunscreen applications due to its high UV absorbance and non-toxicity to normal cells. Nanoscale CeO 2 also showed selective cytotoxicity to cancer cells, thus ceria-containing materials are now regarded for the creation of both preventive and therapeutic compositions. At the same time, the interaction of ceria nanoparticles with cell membranes and phosphate-rich components of sunscreen compositions arise the interest to biocompatibility of ceric phosphates. Crystalline cerium(IV) phosphates can be a promising alternative for nanoscale CeO 2 due to their low solubility, high redox stability and UV protective property. However, to date, there is no information on their toxicity to cancer cells. In this work, using the MTT, Live/Dead and MMP assays, we demonstrated for the first time that the inhibitory impact of ceric phosphates Ce(PO 4 )(HPO 4 ) 0.5 (H 2 O) 0.5 and NH 4 Ce 2 (PO 4 ) 3 on murine melanoma B16/F10 cell line in vitro is comparable to that of nanoscale CeO 2 , at high (500-1000 µg/ml) concentrations. KEYWORDS ceric phosphates, ceria, metabolic activity, reactive oxygen species, UV protectors. ACKNOWLEDGEMENTS This work was supported by Russian Science Foundation (Grant no. 21-73-00294, https://rscf.ru/en/project/21-73-00294/) using the equipment of the JRC PMR IGIC RAS.