Synthesis and Characterisation of Hydrated Calcium Pyrophosphate Phases of Biological Interest

Abstract

The details of a synthesis method for biologically relevant hydrated calcium pyrophosphates (CPPs, Ca 2 P 2 O 7 ·nH 2 O) has been elucidated. Control of the pH (from 3.6 to 5.8) and the temperature (from 25 to 90°C) during the synthesis enabled the preparation of four pure CPP phases within one hour without intermediates: monoclinic and triclinic calcium pyrophosphate dihydrate (CPPD, Ca 2 P 2 O 7 ·2H 2 O), which are the two CPP phases detected in vivo in joints of arthritic patients, monoclinic tetrahydrate β (CPPT, Ca 2 P 2 O 7 ·4H 2 O) and an amorphous phase (a-CPP, Ca 2 P 2 O 7 ·nH 2 O). Four domains corresponding to the four different phases of hydrated calcium pyrophosphate were identified; a-CPP was synthesised over a very wide pH and temperature range (up to 90°C) within the domain of synthesis conditions explored, including physiological conditions (pH 7.4 and 37°C). The as-synthesised hydrated CPP phases were characterised by complementary techniques (powder X-ray diffraction, FTIR and Raman spectroscopy, scanning electron microscopy and thermogravimetry) and chemical analyses. Rietveld refinement analyses of the as-synthesised crystalline phases were performed, and[a] CIRIMAT,

Pyrophosphate Stimulates Differentiation, Matrix Gene Expression and Alkaline Phosphatase Activity in Osteoblasts

“…Increasing concentrations formed a greater amount of precipitant, with an approximate yield of 0.5 mg/mL at 1mM and 0.01 mg/mL at 100μM in alpha MEM. SEM images of the dried precipitant ( Fig 1A ) reveal a spherical/ amorphous morphology, ranging from 50 to 100nm in diameter, similar to what has been reported by Gras and Leeuwin et al [ 17 , 34 ]. The XRD spectra ( Fig 1B ) confirms an amorphous composition, with a broad peak at 30°.…”

“…Interestingly, there are multiple forms of pyrophosphate including soluble sodium pyrophosphate, amorphous calcium pyrophosphate (ACPPi), and calcium pyrophosphate dihydrates (monoclinic crystal mCPPD, triclinic crystal tCPPD, etc.). The physiochemical properties, such as precipitation and dissolution rates, may differ based upon the pyrophosphate form[ 17 ].…”

Clinical Utility of Multi‐Energy Spectral Photon‐Counting Computed Tomography in Crystal Arthritis

“…Multi‐energy SPCCT imaging findings in the meniscus were partly validated using polarized light microscopy (Figure G) and x‐ray diffraction (Figure H) of the crystal scrapings. The diffraction pattern obtained from the sample was assigned as a mixture of monoclinic calcium pyrophosphate dihydrate and triclinic triclinic calcium pyrophosphate dihydrate (). There were no significant peaks to indicate the presence of HA.…”

C-reactive protein (CRP) recognizes uric acid crystals and recruits proteases C1 and MASP1

“…Triclinic-CPPD was from InvivoGen (t-CPPD com.) (#tlrl-cppd) or was prepared (t-CPPD) as previously published by using sodium pyrophosphate as precursor instead of the potassium one 38 .…”