Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Membrane Fluidity01:23

Membrane Fluidity

Cell membranes are composed of phospholipids, proteins, and carbohydrates loosely attached to one another through chemical interactions. Molecules are generally able to move about in the plane of the membrane, giving the membrane its flexible nature called fluidity. Two other features of the membrane contribute to membrane fluidity: the chemical structure of the phospholipids and the presence of cholesterol in the membrane.Fatty acids tails of phospholipids can be either saturated or...
Membrane Fluidity01:26

Membrane Fluidity

Membrane fluidity is explained by the fluid mosaic model of the cell membrane, which describes the plasma membrane structure as a mosaic of components—including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character.
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR01:15

¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR

The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.
Biosynthesis of Lipids01:29

Biosynthesis of Lipids

Microbial membranes exhibit remarkable diversity in lipid composition, reflecting evolutionary adaptations to various environmental conditions. The three domains of life—Bacteria, Archaea, and Eukarya—synthesize membrane lipids through distinct biosynthetic pathways, leading to fundamental structural differences that impact membrane stability, function, and adaptability.Fatty Acid-Based Lipids in Bacteria and EukaryaBacteria and eukaryotes share a common fatty acid biosynthesis pathway, which...
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution00:52

¹H NMR of Conformationally Flexible Molecules: Temporal Resolution

At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
Phase Transitions: Melting and Freezing02:39

Phase Transitions: Melting and Freezing

Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

A Detailed Molecular Model of the Tear Film Lipid Layer.

The journal of physical chemistry. B·2026
Same author

Meibum Lipid Saturation Related to Dry Eye, Age, and Sex Using Nuclear Magnetic Resonance Spectroscopy.

Investigative ophthalmology & visual science·2026
Same author

Effect of increasing chain length on inhibition of evaporation by perfluoro compounds in an in vitro gravimetric assay.

Experimental eye research·2025
Same author

In Memoriam: Michael Albert Lemp.

Cornea·2025
Same author

In Vitro and In Vivo Visualization of Perfluorohexyloctane, an Eye Drop for Dry Eye Disease, Using Infrared Emissivity.

Cornea·2025
Same author

Changes in Human Meibum Lipid Composition Related to the Presence and Severity of Meibomian Gland Dysfunction.

Journal of ocular pharmacology and therapeutics : the official journal of the Association for Ocular Pharmacology and Therapeutics·2024

Related Experiment Video

Updated: Jul 14, 2026

Temperature-Controlled Assembly and Characterization of a Droplet Interface Bilayer
10:11

Temperature-Controlled Assembly and Characterization of a Droplet Interface Bilayer

Published on: April 19, 2021

Temperature-induced conformational changes in human tearlipids hydrocarbon chains.

Douglas Borchman1, Gary N Foulks, Marta C Yappert

  • 1Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40202, USA. borchman@louisville.edu

Biopolymers
|June 30, 2007
PubMed
Summary

Infrared spectroscopy revealed distinct differences in human meibum lipids (ML) and tear fluid lipids (TL). ML exhibits stronger hydrophobic interactions, potentially explaining how eyelid warming enhances ML delivery for dry eye relief.

More Related Videos

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
06:24

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal

Published on: October 31, 2019

Phenol Red Thread-based Sampling Procedure for Untargeted Tear Fluid Lipidomics in Biomarker Discovery
08:16

Phenol Red Thread-based Sampling Procedure for Untargeted Tear Fluid Lipidomics in Biomarker Discovery

Published on: December 12, 2025

Related Experiment Videos

Last Updated: Jul 14, 2026

Temperature-Controlled Assembly and Characterization of a Droplet Interface Bilayer
10:11

Temperature-Controlled Assembly and Characterization of a Droplet Interface Bilayer

Published on: April 19, 2021

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
06:24

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal

Published on: October 31, 2019

Phenol Red Thread-based Sampling Procedure for Untargeted Tear Fluid Lipidomics in Biomarker Discovery
08:16

Phenol Red Thread-based Sampling Procedure for Untargeted Tear Fluid Lipidomics in Biomarker Discovery

Published on: December 12, 2025

Area of Science:

  • Ophthalmology
  • Biophysics
  • Spectroscopy

Background:

  • Human meibum lipids (ML) and tear fluid lipids (TL) play crucial roles in ocular surface health.
  • Understanding their molecular structure and behavior is essential for diagnosing and treating dry eye disease.
  • Previous characterization of these lipid layers has been limited.

Purpose of the Study:

  • To characterize the molecular structure, conformation, and hydrocarbon chain packing of human meibum and tear lipids.
  • To investigate the impact of hydration and temperature on lipid phase transitions.
  • To explore the relationship between lipid structure and therapeutic interventions for dry eye.

Main Methods:

  • Fourier Transform Infrared (FTIR) spectroscopy was employed to analyze lipid samples.
  • Temperature-dependent phase transitions were studied and analyzed using sigmoid equation fitting.
  • Reproducibility and hysteresis of phase transitions were assessed across multiple samples.

Main Results:

  • Infrared spectroscopy successfully characterized the molecular structure and packing of hydrocarbon chains in ML and TL.
  • Meibum lipids (ML) demonstrated stronger hydrophobic interactions compared to tear fluid lipids (TL), indicated by higher transition entropy and enthalpy.
  • Hydration of TL increased phase transition cooperativity, enthalpy, and entropy.

Conclusions:

  • Significant differences exist in the composition and structure of ML and TL.
  • Temperature-induced conformational changes in ML's hydrocarbon chains suggest a mechanism for enhanced lipid delivery with eyelid warming.
  • Infrared spectroscopy is a powerful tool for analyzing tear film lipid structure, providing a foundation for future research on dry eye disease.