Biogenic metal-free carbon dots for synergistic ROS scavenging and imaging in plant cells

Abbas, Khurram, Ge, Zifei, Shao, Renyi, Dai, Chenchen, Usama, Usama, Abbas, Syed Hassan, Hasnain, Mirza Jawad ul, Bandarenka, Hanna ORCID: https://orcid.org/0000-0003-4254-8261 and Bi, Hong 2026. Biogenic metal-free carbon dots for synergistic ROS scavenging and imaging in plant cells. Chemical Engineering Journal 536 , 175925. 10.1016/j.cej.2026.175925

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Abstract

Carbon dots (CDs) have emerged as versatile nanomaterials capable of mediating redox processes in biological systems. However, developing inherently biocompatible, metal-free reactive oxygen species (ROS) modulators remains a challenge. Here, we present a green, precursor-directed strategy to synthesize tea polyphenol and L-arginine derived carbon dots (TL-CDs) for targeted, metal-free regulation of reactive oxygen species in plants. Analytical characterization shows that nitrogen dopants reside predominantly in pyridinic and amine configurations, enhancing the TL-CDs surface polarity and reactivity. The TL-CDs (~2 nm) have surfaces densely decorated with antioxidant phenolic and amino acid moieties, which confer robust excitation-dependent fluorescence and intrinsic superoxide dismutase (SOD)-like catalytic behavior (~90 U mg−1 at 300 μg mL−1). Importantly, TL-CDs maintain strong fluorescence even after prolonged oxidative challenge, with only a moderate (~20%) intensity loss observed. Comprehensive antioxidant assays reveal potent superoxide scavenging activity. Confocal imaging in spinach leaf cells demonstrates efficient uptake and preferential accumulation in mitochondria (the primary sites of ROS generation), enabling precise mitigation of heat- and salt-induced oxidative stress. Controlled efflux studies indicate that TL-CDs gradually exit plant tissues, ensuring their safe elimination and biocompatibility. Integrated experimental and computational analyses provide mechanistic insight into these observations. Collectively, these findings establish TL-CDs as an environmentally friendly platform for enhancing plant resilience via targeted ROS regulation.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Physics and Astronomy
Publisher:	Elsevier
ISSN:	1385-8947
Date of Acceptance:	4 April 2026
Last Modified:	07 Sep 2026 21:50
URI:	https://orca.cardiff.ac.uk/id/eprint/188407

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