Plant nanobionics approach to augment photosynthesis and biochemical sensing

Journal name:
Nature Materials
Year published:
Published online
Corrected online


The interface between plant organelles and non-biological nanostructures has the potential to impart organelles with new and enhanced functions. Here, we show that single-walled carbon nanotubes (SWNTs) passively transport and irreversibly localize within the lipid envelope of extracted plant chloroplasts, promote over three times higher photosynthetic activity than that of controls, and enhance maximum electron transport rates. The SWNT–chloroplast assemblies also enable higher rates of leaf electron transport in vivo through a mechanism consistent with augmented photoabsorption. Concentrations of reactive oxygen species inside extracted chloroplasts are significantly suppressed by delivering poly(acrylic acid)–nanoceria or SWNT–nanoceria complexes. Moreover, we show that SWNTs enable near-infrared fluorescence monitoring of nitric oxide both ex vivo and in vivo, thus demonstrating that a plant can be augmented to function as a photonic chemical sensor. Nanobionics engineering of plant function may contribute to the development of biomimetic materials for light-harvesting and biochemical detection with regenerative properties and enhanced efficiency.

At a glance


  1. Mechanism of SWNT trapping by chloroplast lipid bilayers.
    Figure 1: Mechanism of SWNT trapping by chloroplast lipid bilayers.

    a, Chloroplast autofluorescence was masked from near-infrared images by a long-pass 1,100 nm filter. b, Near-infrared photo still indicating rapid penetration of ss(AT)15–SWNTs through the lipid bilayers of isolated chloroplasts. c, SWNT transport through chloroplast double membrane envelope via kinetic trapping by lipid exchange. df, Bright-field (×100; d) and near-infrared (×100; e) images of isolated chloroplasts indicating uptake of SWNTs coated in ss(AT)15 DNA and chitosan, but not of PVA- and lipid-coated SWNTs (×100; f). g, Change in average SWNT fluorescence in cross-sections of chloroplasts versus external buffer solution. Laser excitation 785 nm at 75 μW.

  2. The ss(AT)15–SWNT lipid exchange with the chloroplasts’ outer envelope via a passive uptake mechanism is dependent on zeta potential.
    Figure 2: The ss(AT)15–SWNT lipid exchange with the chloroplasts’ outer envelope via a passive uptake mechanism is dependent on zeta potential.

    a, Confocal Raman spectroscopy 3D maps localized ss(AT)15 and chitosan SWNTs inside chloroplasts whereas relatively neutral PVA and lipid SWNTs were not present. Chloroplasts were approximately 5 μm in diameter and centred at Z=0. Values correspond to SWNT G-band intensity (1,580 cm–1) under a laser excitation of 658 nm at 145 μW. b, Average percentage of chloroplasts with SWNTs is not influenced by light or temperature conditions. c,d, ss(AT)15–SWNTs quench laurdan fluorescence in DGDG and MGDG liposomes (c), but do not modify laurdan generalized polarization (Gp), an indicator of membrane fluidity (d). Error bars represent s.d. (n=3).

  3. Nanoparticle transport inside isolated chloroplasts and leaves.
    Figure 3: Nanoparticle transport inside isolated chloroplasts and leaves.

    a, CRi Maestro images of ss(AT)15–SWNTs within the leaf lamina of A. thaliana. bd, Co-localization of ss(AT)15–SWNTs near leaf veins (×20; b), in parenchyma cells (×20; c) and chloroplasts in vivo(×63; d). e, Near-infrared fluorescence signal of SWNTs in leaves relative to SWNTs in solution. f, Raman spectroscopy showed broadening of G and G’ SWNT peaks in leaves. g, Temporal patterns of chlorophyll content indicated similar lifespans for leaves with SWNTs and controls. Error bars represent s.d. (n=4). h, Confocal images of chloroplasts assembled with PAA–NC: chlorophyll (green) co-localized with PAA–NC labelled with Alexa Fluor 405 (red). i, TEM images of the SWNT–NC complex. j, Chloroplast TEM cross-section after incubation in SWNT–NC suspension. Nanoparticles localized both in the chloroplasts’ thylakoid membranes (red arrows) and the stroma (yellow arrows). Elemental analysis by ICP-MS of chloroplasts with the SWNT–NC complex detected the presence of cerium at 95 ± 0.1 ppm.

  4. SWNT and nanoceria plant nanobionics.
    Figure 4: SWNT and nanoceria plant nanobionics.

    a, Enhanced photosynthetic activity of isolated chloroplasts with SWNT–NC was shown by electron transfer to DCPIP. b, Higher maximum electron-transport rates in extracted chloroplasts and leaves were quantified by the yield of chlorophyll fluorescence (P <0.05, t-test, n=3–8). c, Electron-transport-rate light curves indicated enhanced photosynthesis above 100 μmol m−2 s−1 for5 mg l−1 SWNT leaves (P < 0.05, t-test, n=5–8). d, SWNTs modified chloroplast ultraviolet, visible and near-infrared absorption spectrum. e, A suspension made mostly of semiconducting SWNTs increased chloroplast reduction of DCPIP whereas a solution enriched with metallic SWNTs (m-SWNTs) had lower effect in photosynthetic activity. f, Increased ROS scavenging by SWNT–NC and PAA–NC inside chloroplasts was quantified by the oxidation of H2DCFDA to DCF. g, Reduction in superoxide concentration was facilitated by nanoparticles localized at chloroplast sites of ROS generation. h,i, NO sensing by ss(AT)15–SWNTs delivered into extracted chloroplasts (h) and in vivoin leaves of A. thaliana (i) was evidenced by a strong quenching in fluorescence for all chiralities. j, In vivo plant sensing set-up whereby a leaf infiltrated with ss(AT)15–SWNTs was excited by a 785 nm epifluorescence microscope. k, ×20 view of ss(AT)15–SWNTs inside a leaf before (left) and after (right) addition of 20 μl dissolved NO solution with three SWNT regions of interest circled. l, Peak intensity–time traces of three ss(AT)15–SWNT regions showed stepwise quenching of SWNT by NO, ranging from 40 to 60% intensity decrease. Error bars represent s.d.

Change history

Corrected online 21 March 2014
In the version of this Article originally published, in Fig. 4k, the scale bar should have been 16 μm, and in the sentence beginning “Leaves assembled with CoMoCAT…” the characteristic fluorescence peak for the (6,5) chirality should have read ‘(980–1,000 nm)’. These errors have now been corrected in the online versions of the Article.


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Author information


  1. Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

    • Juan Pablo Giraldo,
    • Markita P. Landry,
    • Sean M. Faltermeier,
    • Thomas P. McNicholas,
    • Nicole M. Iverson,
    • Ardemis A. Boghossian,
    • Nigel F. Reuel,
    • Andrew J. Hilmer,
    • Fatih Sen,
    • Jacqueline A. Brew &
    • Michael S. Strano
  2. Department of Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA

    • Ardemis A. Boghossian
  3. Department of Biochemistry, Dumlupinar University, Kutahya 43020, Turkey

    • Fatih Sen


J.P.G. and M.S.S. conceived experiments and wrote the paper. J.P.G., M.P.L., S.M.F., T.P.M. and N.M.I. performed experiments and data analysis. A.A.B., F.S., A.J.H., N.F.R. and J.A.B. assisted in experiments and analysis.

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The authors declare no competing financial interests.

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