Towards safer non-volatile tissue fixatives: Evaluation of choline-based ionic liquids for fixing ocular tissues

• Published in: Ecotoxicology and environmental safety Vol. 209; p. 111777
• Main Authors: Deepa, P.R., Nalini, V., Surianarayanan, M., Krishnakumar, S.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.02.2021; Elsevier
• Subjects: Choline; DNA; Fixative; Fixatives; Formaldehyde; Green solvents; Histomorphology; Humans; Ionic Liquids; Ocular tissue; Proteins - analysis; Salts; Solvents effects; Staining and Labeling; Tissue Fixation; Volatile Organic Compounds - analysis; Ionic liquids; Solvents effects; Fixative; Histomorphology; Green solvents; Ocular tissue
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2020.111777

Volatile organic chemicals (VOCs) are routinely used for processing biological tissue samples in clinical laboratories. Recognizing their serious health and environmental impacts, a few non-volatile green solvents (choline based ionic liquids, ILs) were evaluated as tissue fixatives here. Microscopic evaluation of histo-morphology, fixation and staining quality, and macromolecular integrity (DNA and proteins) were assessed in human eye tissues (sclera, choroid, retinal layers and retinal pigmented epithelium, eyelid and orbit) after IL-fixation. Formalin-fixed tissues were used as standard reference. Microscopic examination revealed favorable histomorphology, tissue fixation and staining characteristics in most tissues immersed in ILs. Time taken to fix, and stability over a period of time (24 h, 48 h, 1 week, 1 month) was also recorded. Electrophoretic analysis revealed stability of cellular proteins and nucleic acids in IL-fixed scleral tissues. Heterogeneity in tissue fixation property relative to the type of ocular tissue, duration of fixation and storage, warrant further design and optimization of ILs to fix biological tissues. The simple cholinium salts based ILs tested here show favorable potential for tissue fixation application, and as an alternative approach to the use of VOCs, towards sustainable biomedical practice. •VOCs in tissues fixation have serious health/environmental impacts.•Cholinium ionic liquids tested in ocular tissues.•Promising tissue fixation properties shown.•Lead for further IL design and optimization as fixative.