Microscope reveals photosynthesis differences
- A team led by Toru Kondo at Japan’s National Institute for Basic Biology reported a microscope that measures ultrafast photosynthesis signals in single light-harvesting structures. - The instrument reaches roughly 300-nanometer spatial resolution, under-200-femtosecond timing, and about 10^-7 absorbance sensitivity, letting researchers separate nearly identical kinetic components. - The work targets hidden variation inside photosynthetic antennae that average measurements blur, with implications for crop and artificial-light systems. (nibb.ac.jp)
Photosynthesis starts when pigment molecules catch light and pass that energy along like runners in a relay. A team led by Toru Kondo has now built a microscope that can watch those first handoffs in individual light-harvesting structures. (nibb.ac.jp) (phys.org) Most plant and bacterial photosynthesis studies average signals from huge numbers of molecules at once. That smooths out local differences, even though pigment arrangements can vary from particle to particle and from one spot to another. (nibb.ac.jp) Kondo’s group used transient absorption microscopy, which tracks how a sample’s light absorption changes immediately after a laser pulse. That method can capture excited-state relaxation and energy transfer on the femtosecond timescale, where a femtosecond is one quadrillionth of a second. (nibb.ac.jp) The technical problem was sensitivity. The group said fluorescence methods have struggled to follow ultrafast multistep processes and non-fluorescent “dark” states, while transient absorption had not previously reached near single-molecule sensitivity. (nibb.ac.jp) (phys.org) Their new setup combines single-objective absorption microscopy, a balanced detector, and lock-in amplification. The result is about 300-nanometer spatial resolution, less than 200-femtosecond temporal resolution, and transient-absorption sensitivity of roughly 10^-7 in absorbance. (nibb.ac.jp) The paper was published in 2026 in The Journal of Physical Chemistry Letters by Shun Arai, Shogo Matsubara, and Toru Kondo. The researchers tested the system on chlorophyll-derivative aggregates that mimic photosynthetic light-harvesting antennae. (pblab.nibb.ac.jp) (biorxiv.org) In those model antennae, the team said it could separate two kinetic components with nearly identical time constants by comparing the distributions of those time constants, not just their averages. It also quantified absorbance change, fluorescence intensity, fluorescence efficiency, and fluorescence peak-intensity ratios for each component. (biorxiv.org) That matters because photosynthetic antennae are not perfectly uniform machines. They keep working even as protein scaffolds fluctuate and individual assemblies adopt slightly different structures, and those hidden differences can shape how energy moves after light hits. (biorxiv.org) (nibb.ac.jp) The Japanese institutions behind the work said the microscope should help probe regulatory mechanisms in photosynthetic photochemistry and could guide the design of artificial photofunctional materials. The closing point is simple: the first instant of photosynthesis no longer has to be treated as an average. (nibb.ac.jp)
