Quantification of calcium content in bone by using ToF-SIMS–a first approach

Abstract

The determination of the spatially resolved calcium distribution and concentration in bone is essential for the assessment of bone quality. It enables the diagnosis and elucidation of bone diseases, the course of bone remodelling and the assessment of bone quality at interfaces to implants. With time-of-flight secondary ion mass spectrometry (ToF-SIMS) the calcium distribution in bone cross sections is mapped semi-quantitatively with a lateral resolution of up to 1 μm. As standards for the calibration of the ToF-SIMS data calcium hydroxyapatite collagen scaffolds with different compositions were synthesized. The standards were characterised by loss of ignition, x-ray diffractometry (XRD) and x-ray photoelectron spectroscopy (XPS). The secondary ion count rate for calcium and the calcium content of the standards show a linear dependence. The obtained calibration curve is used for the quantification of the calcium content in the bone of rats. The calcium concentration within an animal model for osteoporosis induction is monitored. Exemplarily the calcium content of the bones was quantified by XPS for validation of the results. Furthermore a calcium mass image is compared with an XPS image to demonstrate the better lateral resolution of ToF-SIMS which advances the locally resolved quantification of the calcium content.

Investigation of strontium transport and strontium quantification in cortical rat bone by time-of-flight secondary ion mass spectrometry

“…Twenty-five kiloelectronvolt Bi þ 3 primary ions were used for ToF-SIMS imaging, for sputtering, a 1 keV O þ 2 beam was used. [26,29]. These characteristic peaks and fragmentation patterns of collagen and HAP were also obtained from mineralized bone tissue.…”

“…Therefore, appropriate standards that possess a nearly identical composition as the analysed material are required. Henss et al [29] showed successful quantification of calcium in bone by ToF-SIMS, using standards with an almost identical composition as natural bone.…”

Small changes in bone structure of female α7 nicotinic acetylcholine receptor knockout mice

“…In addition to the gender change we also included some complementary methods. One of them was “time of flight secondary ion mass spectrometry” (ToF-SIMS) for quantification of bone calcium ion (Ca 2+ ) content and proline fragments that is one of the main amino acids of collagen [ 13 - 16 ]. The principle of ToF-SIMS is that primary ions hit the sample surface, releasing secondary ions from the surface, that were collected by an analyzer for producing single mass spectra and mass images of the sample surface [ 14 ].…”

Atomic spectrometry update: review of advances in the analysis of clinical and biological materials, foods and beverages

“…[71][72][73] Minakata et al 71 applied MALDI-Q-TOF to quantify Au and Pt in tissues aer complexation with DDC. The use of other MS instrumentation for the analysis of biological tissues was demonstrated in three reports.…”