CrystEngComm Blog

A new paper by Lee et al. who carried out research at the National Central University in China, finally explains the formation of gout.  Gout is an inflammatory arthritic condition caused by the deposition of crystals of monosodium urate monohydrate (MSUM) in joints and tendons.  Traditionally associated with over-indulgent consumption of alcohol and rich food, gout was known as the disease of kings.  It has become more common in recent years, affecting 2-3% of the Western population at some point during their lives.

Development of gout is related to raised levels of uric acid in the blood (hyperuricemia).  However, the mechanism of crystallisation of MSUM and the fact that only some people with hyperuricemia develop gout were not understood, but are now unveiled in this new paper.

The morphology of the MSUM formed from uric acid was studied under various Na⁺ ion concentrations, under conditions mimicking the body (pH 7.4, 37^oC).  The formation of a metastable “beachball structure” which converts to “urchin-like aggregates” and “bow-like aggregates” depends on the Na⁺ ion concentration and it is suggested that the pathogenesis of gout may be related to the transformation of “beachballs” to needles.

When the pH is lowered by adding lactic acid, which would occur during inflammatory response, uric acid dihydrate (UAD) is formed.  As the pH returns to normal, this converts to MSUM, causing an inflammatory response and generating a self-sustaining cycle, as shown in the diagram below.

The presence of hyaluronate, Na⁺, K⁺ and Ca²⁺ is found to affect the development of gout and a new MSUM “fishtail” morphology was observed in hyaluronate-, Na⁺– and Ca²⁺– containing solutions.  A highly water soluble hyaluronate-Ca-urate complex was identified and authors suggest that disruption of this complex would lead to MSUM deposition, causing gout.  Thus, people could have hyperuricemia but not develop gout, if their physiological conditions maintain the complex.

For more information, see the paper at:

The culprit of gout: triggering factors and formation of monosodium urate monohydrate

Meng Hsiu Chih, Hung Lin Lee and Tu Lee

CrystEngComm, 2016, Advance Article
DOI: 10.1039/C5CE01656H, Paper

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Gwenda Kyd has a PhD in metallocarborane chemistry from the University of Edinburgh. Other research work includes the spectroscopic study of the structure of glasses and organometallic electron-transfer reactions and the preparation of new inorganic phosphors. She has recently published a book on chemicals from plants.

A new red-emitting nanophosphor with potential use in white light-emitting diodes (LEDs) has recently been reported by Mi and colleagues.

White LEDs are used for lighting as they use little energy, have high brightness and long lifetimes and are considered environmentally friendly. Currently, these LEDs consist of a combination of a yellow-emitting phosphor and a blue LED chip. However, the lack of a red component is problematic, leading to a low colour rendering index (in other words, some colours do not appear naturalistic) and a high colour temperature (giving light a blue hue). Other possible methods of generating white LEDs that use red phosphors are limited by the low stability and efficiency of commercial sulphide-based red phosphors. Now, Mi and colleagues report an efficient and stable europium-based red phosphor that could solve the problem and improve the suitability of white LEDs for certain medical applications.

The phosphor Ca₉Eu(PO₄)₇ was prepared using hydrothermal methods from calcium- and europium- nitrates and phosphoric acid. It shows a red emission at 616nm under excitation at 397nm. This is attributed to the ⁵D₀ →⁷F₂ transition in Eu³⁺, which will only happen when the Eu ion occurs in sites without inversion symmetry (as it is parity forbidden).

When the phosphor was doped (in other words, when Eu was partially replaced by Gd, La or Y), the emission intensity decreased. The pH value of the synthesis reaction was found to alter the morphology of the phosphor (see the diagram below) from rods to spheres, which had different luminescence properties. The most favourable properties were obtained from rods obtained at pH 7, attributed to the smallest number of lattice defects being formed at this pH. The rods are approximately 100nm long with an aspect ratio (long axis length to width ratio) of 2.5. This phosphor shows a good colour saturation index (R = 2.4) and future studies to optimise its properties could lead to potential application in white LEDs.

For more details read the full paper at:

Hydrothermal synthesis and photoluminescence properties of Ca₉Eu(PO₄)₇ nanophosphors
Jiacheng Sun, Xiaoyun Mi, Lijian Lei, Xiaoying Pan, Shuyi Chen, Zan Wang, Zhaohui Bai and Xiyan Zhang
CrystEngComm, 2015
DOI: 10.1039/C5CE01289A

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Gwenda Kyd has a PhD in metallocarborane chemistry from the University of Edinburgh. Other research work includes the spectroscopic study of the structure of glasses and organometallic electron-transfer reactions and the preparation of new inorganic phosphors. She has recently published a book on chemicals from plants.