The application of midIR spectroscopy towards human cell and tissue samples is impaired by the need for technical solutions and lacking sample standards for technology development. We here present the standardization of stable test samples for the continuous development and testing of novel optical system components. We have selected cell lines representing the major cellular skin constituents keratinocytes and fibroblasts (NIH-3T3, HaCaT). In addition, two skin cancer cell types (A-375 and SK-MEL-28 cells) were analyzed. Cells were seeded on CaF₂ substrates and measured dried and under aqueous medium as well as fixated and unfixated. Several independent cell preparations were analyzed with an FTIR spectrometer in the wave number range from 1000 - 4000 cm^-1. The obtained data demonstrate that fixed and dehydrated cells on CaF₂ can be stored in pure ethanol for several weeks without significant losses in quality of the spectral properties. The established protocol of cell seeding on CaF₂ substrates, chemical fixation, dehydration, storage under ethanol and air-drying is suitable for the production of reliable midIR standards. The retrieved spectra demonstrate that fixed cells on CaF₂ can be prepared reproducibly; with stable midIR spectral properties over several weeks and properties mimicking reliable unfixed cells. Moreover, the fixated samples on CaF₂ show clear differences in the cell type specific spectra that can be identified by principle component analysis. In summary, the standardized cell culture samples on CaF₂ substrates are suitable for the development of a midIR device and the optimization of the specific midIR spectra.

Date Published: 5 March 2015
PDF: 6 pages
Proc. SPIE 9315, Design and Quality for Biomedical Technologies VIII, 931507 (5 March 2015); doi: 10.1117/12.2080251

Published in SPIE Proceedings Vol. 9315:
Design and Quality for Biomedical Technologies VIII
Ramesh Raghavachari; Rongguang Liang, Editor(s)