Evaluation of electrolyte element composition in human tissue by laser-induced breakdown spectroscopy (LIBS)

Abstract

Laser-induced breakdown spectroscopy (LIBS) enables the direct measurement of cell electrolyte concentrations. The utility of LIBS spectra in biomarker studies is limited because these studies rarely consider basic physical principles. The aim of this study was to test the suitability of LIBS spectra as an analytical method for biomarker assays and to evaluate the composition of electrolyte elements in human biomaterial. LIBS as an analytical method was evaluated by establishing KCl calibration curves to demonstrate linearity, by the correct identification of emission lines with corresponding reference spectra, and by the feasibility to use LIBS in human biomaterial, analyzing striated muscle tissues from the oral regions of two patients. Lorentzian peak fit and peak area calculations resulted in better linearity and reduced shot-to-shot variance. Correct quantitative measurement allowed for differentiation of human biomaterial between patients, and determination of the concentration ratios of main electrolytes within human tissue. The clinical significance of LIBS spectra should be evaluated using peak area rather than peak intensity. LIBS might be a promising tool for analyzing a small group of living cells. Due to linearity, specificity and robustness of the proposed analytical method, LIBS could be a component of future biomarker studies.

Assessment of the Electrolyte Heterogeneity of Tissues in Mandibular Bone-Infiltrating Head and Neck Cancer Using Laser-Induced Breakdown Spectroscopy

“…The tissue spectra recorded in this study depict the tissue-specific signal, including the immediate spatial environment within the laser spot diameter of our LIBS-based experimental setup [ 19 ]. The inferior alveolar nerve anatomically courses through the mandible within a bony canal [ 26 ].…”

“…These included Ca with calcium oxide (CaO) and calcium hydroxide (CaOH) emission lines and K, while Na was less suitable for capturing tissue heterogeneity in this study. Further discussion regarding the wavelengths used in this study is already part of previous publications on calibration experiments with K on native sample material [ 19 ] and previous works on the use of LIBS as a rapid bone analysis technique [ 20 ] and LIBS-based depth profiling [ 23 ].…”

“…As with our previous LIBS studies [ 19 , 20 , 23 ], minor limitations must also be considered in this study. The number of patients limited the number of spectra available in this study.…”

“…After optimizing the technical requirements of a LIBS-based experimental setup for instrumentation on native sample material and developing a robust method for the evaluation of LIBS spectra [ 19 ], we were able to describe the use of LIBS as a promising and innovative possibility for rapid bone analysis for the first time [ 20 ]. Subsequently, LIBS-based tracking of the electrolytes calcium (Ca), potassium (K), and sodium (Na), which are involved in the progression of head and neck tumors [ 21 ] and in the invasion of tumors into bone [ 22 ], was used to record depth profiles at the border of bone-infiltrating head and neck tumors [ 23 ].…”

Parametric studies of liquid LIBS for agricultural applications

“…This plasma emits a spectrum which contains atomic and ionic emission lines of various elements present in the sample, which is then analysed to determine the elemental composition of the material. LIBS has got a wide variety of applications due to several advantages, including its capability for multielemental analysis, remote sensing, in-situ monitoring, and the absence of the need for sample preparation [13][14][15][16]. For example, LIBS has been used for precise elemental analysis of soil samples [15].…”