Arraying of Single Cells for Quantitative High Throughput Laser Ablation ICP-TOF-MS

Abstract

Arraying of single cells for mass spectrometric analysis is a considerable bioanalytical challenge. In this study, we employ a novel single cell arraying technology for quantitative analysis and isotopic fingerprinting by laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOF-MS). The single cell arraying approach is based on a piezo-acoustic microarrayer with software for automated optical detection of cells within the piezo dispense capillary (PDC) prior to arraying. Using optimized parameters, single cell occupancy of >99%, high throughput (up to 550 cells per hour), and a high cell recovery of >66% is achieved. LA-ICP-TOF-MS is employed to detect naturally occurring isotopes in the whole mass range as fingerprints of individual cells. Moreover, precise quantitative determination of metal-containing cell dyes is possible down to contents of ∼100 ag using calibration standards which were produced using the same arrayer.

Needles in haystacks: using fast-response LA chambers and ICP-TOF-MS to identify asbestos fibres in malignant mesothelioma models

“…21 In the TOF experiments, data for a large mass range (between Na and U) was collected, but many elements in this range are not present in either asbestos or the MSTO-211H cells and gave rise to only background signal. Subsequent data analysis therefore focussed in on 10 elements that are either matrix constituents of the bres or have been known to substitute into one of the bre types studied ( 23 Na, 24 Mg, 27 Al, 28 Si, 31 P, 39 K, 40 Ca, 48 Ti, 55 Mn and 56 Fe). The outer boundary of each bre was identied through visual inspection of the images.…”

“…A standard laser ablation system was used in order to provide peak widths that were considerably longer than the time taken to scan across the selected mass range. The cells contained detectable levels of endogenous 23 Na, 24 Mg and 31 P, which facilitated registration of the LA-ICP-MS images to the microscopy data (see ESI †). Signals for 24 Mg, 27 Al and 29 Si in the bres were above the cellular background, conrming that LA-ICP-MS is a viable technique for visualisation of the bres within complex matrices.…”

“…The cells contained detectable levels of endogenous 23 Na, 24 Mg and 31 P, which facilitated registration of the LA-ICP-MS images to the microscopy data (see ESI †). Signals for 24 Mg, 27 Al and 29 Si in the bres were above the cellular background, conrming that LA-ICP-MS is a viable technique for visualisation of the bres within complex matrices. However, the instrumentation used for the feasibility experiment may be unable to meet the demands of large-scale research studies into asbestos in the long-term.…”

“…1 panel H). The 24 Mg signals were strongest for amosite, where Mg accounts for >20% of the nominal composition of its cummingtonite form. During analysis, a collision-reaction cell was used to reduce nitrogen and argon related interferences, enabling 40 Ca to be measured without interference from 40 Ar and 56 Fe to be measured without polyatomic interference from 40 Ar 16 O (see ESI †).…”

“…The drive towards use of higher speed LA systems has contributed to a rise in the popularity of time-of-ight (TOF) ICP-MS systems for imaging applications. 19,[22][23][24] TOF mass analysers enable pseudosimultaneous detection of the full mass range, which is advantageous for analysis of the fast transient signals from modern LA units. These recent technological developments have therefore expanded the capability of LA-ICP-MS to the point where it now warrants investigation as a tool to rapidly detect and identify bres in tissue.…”