Label-free cellular imaging of lipid composition of individual lipid droplets using multiplex CARS microscopy

Lipid multilayer gratings are promising optical biosensor elements that are capable of transducing analyte binding events into changes in an optical signal. Unlike solid state transducers, reagents related to molecular recognition and signal amplification can be incorporated into the lipid grating ink volume prior to fabrication. Here we describe a strategy for functionalizing lipid multilayer gratings with a DNA aptamer for the protein thrombin that allows label-free analyte detection. A double cholesterol-tagged, double-stranded DNA linker was used to attach the aptamer to the lipid gratings. This approach was found to be sufficient for binding fluorescently labeled thrombin to lipid multilayers with micrometer-scale thickness. In order to achieve label-free detection with the sub-100 nm-thick lipid multilayer grating lines, the binding affinity was improved by varying the lipid composition. A colorimetric image analysis of the light diffracted from the gratings using a color camera was then used to identify the grating nanostructures that lead to an optimal signal. Lipid composition and multilayer thickness were found to be critical parameters for the signal transduction from the aptamer functionalized lipid multilayer gratings.

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Sterol Carrier Protein-2 Expression Modulates Protein and Lipid Composition of Lipid Droplets

Journal of Biological Chemistry ◽

10.1074/jbc.m100560200 ◽

2001 ◽

Vol 276 (27) ◽

pp. 25324-25335 ◽

Cited By ~ 51

Author(s):

Barbara P. Atshaves ◽

Stephen M. Storey ◽

Avery L. McIntosh ◽

Anca D. Petrescu ◽

Olga I. Lyuksyutova ◽

...

Keyword(s):

Lipid Composition ◽

Lipid Droplets ◽

Carrier Protein ◽

Sterol Carrier Protein ◽

Sterol Carrier Protein 2

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Multiplex coherent anti-Stokes Raman scattering microspectroscopy detection of lipid droplets in cancer cells expressing TrkB

Scientific Reports ◽

10.1038/s41598-020-74021-z ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Tiffany Guerenne-Del Ben ◽

Vincent Couderc ◽

Ludovic Duponchel ◽

Vincent Sol ◽

Philippe Leproux ◽

...

Keyword(s):

Cancer Cells ◽

Lipid Droplets ◽

Live Cells ◽

Label Free ◽

Colorectal Cancer Cell Lines ◽

Invasive Method ◽

Dye Staining ◽

Cytoplasmic Lipid Droplets ◽

Anti Stokes ◽

Cell Fixation

Abstract For many years, scientists have been looking for specific biomarkers associated with cancer cells for diagnosis purposes. These biomarkers mainly consist of proteins located at the cell surface (e.g. the TrkB receptor) whose activation is associated with specific metabolic modifications. Identification of these metabolic changes usually requires cell fixation and specific dye staining. MCARS microspectroscopy is a label-free, non-toxic, and minimally invasive method allowing to perform analyses of live cells and tissues. We used this method to follow the formation of lipid droplets in three colorectal cancer cell lines expressing TrkB. MCARS images of cells generated from signal integration of CH2 stretching modes allow to discriminate between lipid accumulation in the endoplasmic reticulum and the formation of cytoplasmic lipid droplets. We found that the number of the latter was related to the TrkB expression level. This result was confirmed thanks to the creation of a HEK cell line which over-expresses TrkB. We demonstrated that BDNF-induced TrkB activation leads to the formation of cytoplasmic lipid droplets, which can be abolished by K252a, an inhibitor of TrkB. So, MCARS microspectroscopy proved useful in characterizing cancer cells displaying an aberrant lipid metabolism.

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