Journal Article

Characterization of connective tissues using near-infrared spectroscopy and imaging

Töyräs, Juha, Afara, Isaac O., Torniainen, Jari, Sarin, Jaakko K., Querido, William, Nippolainen, Ervin, Kandel, Shital, Pleshko, Nancy, Shaikh, Rubina

2021

Overview

Near-infrared (NIR) spectroscopy is a powerful analytical method for rapid, non-destructive and label-free assessment of biological materials. Compared to mid-infrared spectroscopy, NIR spectroscopy excels in penetration depth, allowing intact biological tissue assessment, albeit at the cost of reduced molecular specificity. Furthermore, it is relatively safe compared to Raman spectroscopy, with no risk of laser-induced photothermal damage. A typical NIR spectroscopy workflow for biological tissue characterization involves sample preparation, spectral acquisition, pre-processing and analysis. The resulting spectrum embeds intrinsic information on the tissue’s biomolecular, structural and functional properties. Here we demonstrate the analytical power of NIR spectroscopy for exploratory and diagnostic applications by providing instructions for acquiring NIR spectra, maps and images in biological tissues. By adapting and extending this protocol from the demonstrated application in connective tissues to other biological tissues, we expect that a typical NIR spectroscopic study can be performed by a non-specialist user to characterize biological tissues in basic research or clinical settings. We also describe how to use this protocol for exploratory study on connective tissues, including differentiating among ligament types, non-destructively monitoring changes in matrix formation during engineered cartilage development, mapping articular cartilage proteoglycan content across bovine patella and spectral imaging across the depth-wise zones of articular cartilage and subchondral bone. Depending on acquisition mode and experiment objectives, a typical exploratory study can be completed within 6 h, including sample preparation and data analysis. This protocol describes how to perform near-infrared spectroscopy and imaging of connective tissues. Detailed guidelines are provided for sample preparation, spectral acquisition and data pre-processing and analysis, with example applications.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 631/136/819 / 631/1647/245/2226 / 631/1647/527/1989 / 631/443/63 / 639/624/1111/55 / Analytical Chemistry / Animals / Biological materials / Biological research / Biological Techniques / Biology, Experimental / Biomedical and Life Sciences / Bone imaging / Cartilage / Cartilage (articular) / Cartilage, Articular - chemistry / Composition / Computational Biology/Bioinformatics / Connective tissue / Connective Tissue - metabolism / Connective Tissue - physiology / Connective Tissue Cells - cytology / Connective tissues / Data analysis / Data processing / Diagnostic software / Diagnostic systems / Humans / I.R. radiation / Infrared analysis / Infrared imaging / Infrared radiation / Infrared spectra / Infrared spectroscopy / Laser damage / Life Sciences / Microarrays / Near infrared radiation / Near infrared spectroscopy / Nondestructive testing / Observations / Organic Chemistry / Penetration depth / Proteoglycans / Proteoglycans - chemistry / Protocol / Raman spectroscopy / Sample preparation / Specimen Handling - methods / Spectroscopic analysis / Spectroscopy, Near-Infrared - methods / Spectrum analysis / Structure-function relationships / Subchondral bone / Tissues / Workflow