Interaction between the purple bacterial
reaction center and the quantum dots

Interaction between the purple bacterialreaction center and the quantum dots

Quantum dots are nano-crystals made of semiconducting material. Quantum dots vary in size from a single nanometer to several tens of nanometers, which makes it possible for them to possess quantum-mechanical properties similar to single molecules. Quantum dots have uncommon fluorescence properties with a wide excitation spectrum, and their fluorescence peak position strongly depends on their size, e.g., a bigger nano-crystal emits a redder light. Quantum dots are more lightfast than organic dyes, and this property allows for their prospective use in many scientific and technical applications, such as fluorescent probes in medicine and biology [1].

The process of generating a quantum dot involves covering a nano-crystal (core) with 1 to 3 atomic layers of insulation cover (shell), which raises the quantum yield to 70%. Covered with a shell, nano-crystals can be functionalized with different organic molecules for their solubilization in different solvents, or they can be linked to other molecules for their visualization in vivo [2]. In photobiology applications, quantum dots could be utilized as light-harvesting complexes for photosynthetic reaction centers because they collect light more efficiently than natural light antennas. Therefore, in theory, these molecules could raise the efficiency of primary photosynthetic stages by several fold [3]. The illustration presents a scheme showing the interaction between the purple bacterial (Rb. sphaeroides) reaction center that is integrated in the liposome membrane and the quantum dots (CdSe core and ZnS shell), which are situated inside the liposome or integrated in the membrane but lack an organic cover (PEG).

Date: Nov 17, 2009


  1. Medintz IL et al., Potential clinical applications of quantum dots. Int J Nanomedicine. 2008;3(2):151—67
  2. Stroh M et al., Quantum dots spectrally distinguish multiple species within the tumor milieu in vivo. Quantum dots spectrally distinguish multiple species within the tumor milieu in vivo. Nat Med. 2005 Jun;11(6):678—82. Epub 2005 May 8.
  3. Govorov, AO et al., Enhanced optical properties of a photosynthetic system conjugated with semiconductor nanoparticles: The role of Förster transfer, Advanced Materials, 20, 4330—4335 (2008).