Recent developments, applications and challenges for carbon quantum dots as a photosynthesis enhancer in agriculture

Abstract

Since the world's population is expanding, mankind may be faced with a huge dilemma in the future, which is food scarcity. The situation can be mitigated by employing sustainable cutting-edge agricultural methods to maintain the food supply chain. In recent years, carbon quantum dots (CQD), a member of the well-known carbon-based nanomaterials family, have given rise to a new generation of technologies that have the potential to revolutionise horticulture and agriculture research. CQD has drawn much attention from the research community in agriculture owing to their remarkable properties such as good photoluminescence behaviour, high biocompatibility, photo-induced electron transfer, low cost, and low toxicity. These unique properties have led CQD to become a promising material to increase plant growth and yield in the agriculture field. This review paper highlights the recent advances of CQD application in plant growth and photosynthesis rate at different concentrations, with a focus on CQD uptake and translocation, as well as electron transfer mechanism. The toxicity and biocompatibility studies of CQD, as well as industrial scale applications of CQD for agriculture are discussed. Finally, the current challenges of the present and future perspectives in this agriculture research are presented.

Fig. 1. Properties of CQD and their effects on plants.

Fig. 2. The penetration pathway of CQD via the leaf tissue.

Fig. 3. (i)The laser scanning microscopy (LSM) images of CQD uptake into the mung bean root, stem, cotyledon, and leaf. (ii) Laser scanning microscopy (LSM) images of longitudinal sections from root and stem treated with CQD. (Reproduced from ref. with permission from the American Chemical Society, Copyright © 2016).

Fig. 4. (i) The effect of CQD on the yield and morphology of lettuce plant (reproduced from ref. with permission from the American Chemical Society, Copyright © 2017). (ii) The CQD effect on the yield and morphology of mung bean (a) (Reproduced from ref. with permission from the American Chemical Society, Copyright © 2016). (b and c) (Reproduced from ref. with permission from the Shweta Tripathi et al., Copyright © 2014).

Fig. 5. Division of two reaction compartments within the chloroplast.

Fig. 6. The schematic pathway of electron transfer (reproduced from ref. with permission from the Royal Society of Chemistry, Copyright © 2014).

Fig. 7. PL spectrum of CQD, chloroplast and CQD conjugated CLP at 390, 420, 442 nm excitation wavelength. (Reproduced from ref. with permission from the Royal Society of Chemistry, Copyright © 2014).

Fig. 8. Toxicological study of (a) different concentrations of CQD on zebrafish larvae at 120 hpe; (b) effects of exposure to 2000 ppm CQD in developing zebrafish embryos. (Reproduced from ref. Copyright © 2016 with permission from the Elsevier Masson SAS. All right reserved.)