A review published in npj Biological Physics and Mechanics describes recent advances in laser optical tweezers (LOTs) for studying biomolecular mechanisms at the single-molecule level. The review covers the technology's functionality, applications in DNA compaction, protein misfolding, transcription, translation, and membrane fusion, and discusses its role in a post-reductionist research framework.
Illuminating Life's Machinery: How Laser Optical Tweezers Are Revolutionizing Single-Molecule Biology
The Technology at a Glance
Laser optical tweezers use focused laser beams to trap and manipulate particles, generating a 3D optical potential that confines transparent dielectric particles. The trapping force arises from the intensity gradient. A typical LOT system comprises a coherent laser source, beam-shaping optics, and a high-numerical-aperture objective lens.
"The review examined LOT applications in a post-reductionist framework, preserving molecular-level precision while situating measurements in biologically relevant contexts."
Key Applications in Molecular Biology
The review examined LOT applications across several critical biological processes, including DNA compaction, protein misfolding, transcription, translation, and membrane fusion. Researchers integrated LOTs with complementary techniques such as fluorescence microscopy.
DNA Compaction Under the Microscope
A 2023 study by Sun et al. investigated DNA compaction under physiological conditions by tethering individual DNA molecules between two beads. Force-dependent transitions between compaction and decompaction states were observed. Sun et al. cautioned that the results may not accurately reflect chromatin's natural behavior due to limited histone binding and applied tensions.
Watching Proteins Fold—and Misfold
LOTs enabled direct observation of protein folding trajectories and quantification of mutant protein templates' influence on folding behavior of normal proteins. This represents a significant step forward in understanding how misfolding propagates in diseases like Alzheimer's and Parkinson's.
The Machinery of Life: Transcription, Translation, and Membrane Fusion
Measurements of SNARE protein assembly provided support for the zippering mechanism that drives membrane fusion, a fundamental process for neurotransmitter release and cellular communication.
A Post-Reductionist Framework
Rather than stripping biological systems to their bare components, the review positions LOTs as tools that can maintain molecular-level precision while operating within biologically relevant contexts—a key shift toward more holistic single-molecule studies.
Journal Reference:
Pápayová, K., Žoldák, G. 2026. Laser optical tweezers for studies of biomolecules in the post-reductionist era. npj Biol. Phys. Mech. 3(7). https://www.nature.com/articles/s44341-026-00036-8