Quantitative bioimaging of trace elements in the human lens by LA-ICP-MS

Abstract

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used for the quantitative imaging of Fe, Cu and Zn in cryostat sections of human eye lenses and for depth profiling analysis in bovine lenses. To ensure a tight temperature control throughout the experiments, a new Peltier-cooled laser ablation cell was employed. For quantification purposes, matrix-matched laboratory standards were prepared from a pool of human lenses from eye donors and spiked with standard solutions containing different concentrations of natural abundance Fe, Cu and Zn. A normalisation strategy was also carried out to correct matrix effects, lack of tissue homogeneity and/or instrumental drifts using a thin gold film deposited on the sample surface. Quantitative images of cryo-sections of human eye lenses analysed by LA-ICP-MS revealed a homogeneous distribution of Fe, Cu and Zn in the nuclear region and a slight increase in Fe concentration in the outer cell layer (i.e. lens epithelium) at the anterior pole. These results were assessed also by isotope dilution mass spectrometry, and Fe, Cu and Zn concentrations determined by ID-ICP-MS in digested samples of lenses and lens capsules.

A novel calibration strategy based on internal standard–spiked gelatine for quantitative bio-imaging by LA-ICP-MS: application to renal localization and quantification of uranium

“…Nevertheless, further calibration strategies are found in the literature including the solution-based calibration [27], fabrication xerogel solid calibration standards which are more suitable for the calibration of glasses and silicate matrices [28], the synthesis of metal-spiked polymer films [29], the use of dried droplets or dried matrix spots (DMS) deposited on different substrates [30][31][32][33][34], and the spiking and sectioning of gelatine droplets, whose use has increased noticeably in recent years for the quantitative analysis of biological tissues [35][36][37][38][39][40][41]. For internal standardization, three different approaches are mainly described in the literature for the quantitative elemental imaging of biological samples: (i) the simultaneous nebulization of a standard solution [42], (ii) the use of an element naturally occurring in the sample [43][44][45], and (iii) the addition of an internal standard-spiked layer between the sample and support or on the sample [46][47][48][49][50][51]. In this study, a thulium (IS)doped gelatine, located between the support and the tissue, was prepared in order to incorporate a more appropriate internal standard than 13 C, as its feasibility for quantitative LA-ICP-MS imaging has been queried recently [52][53][54].…”

Elemental imaging (LA-ICP-MS) of zebrafish embryos to study the toxicokinetics of the acetylcholinesterase inhibitor naled

“…The element 31 P signal exhibited a similar ratio and could be used for the normalization as well (ESM Fig. S2) [18, 24, 44]. In the region of the swim bladder, the 12 C signal intensity and the thickness were deviating.…”

Analytical Methods for Imaging Metals in Biology: From Transition Metal Metabolism to Transition Metal Signaling

“…54,59 Thicker samples can also be used, and depth profiling by ablating through thick samples can provide useful information about changes in elemental concentration in the z -dimension. 60 LA-ICPMS is a destructive technique, so any other imaging must be done before LA-ICPMS analysis.…”