Synthesis and Characterization of Green Carbon Dots for Scavenging Radical Oxygen Species in Aqueous and Oil Samples.

Clarissa Murru,Marta Elena Díaz-García,Rosana Badía-Laíño

doi:10.3390/antiox9111147

Abstract

Carbon dots (CDs) due to their unique optical features, chemical stability and low environmental hazard are applied in different fields such as metal ion sensing, photo-catalysis, bio-imaging and tribology, among others. The aims of the present research were to obtain CDs from vegetable wastes (tea and grapes) as carbon sources and to explore their potential properties as radical scavengers. CDs from glutathione/citric acid (GCDs) were synthetized for comparison purposes. The CDs were investigated for their chemical structure, morphology, optical and electronical properties. The antioxidant activity has been explored by DPPH and Folin-Ciocelteau assays in aqueous media. Due to their solubility in oil, the CDs prepared from tea wastes and GCDs were assayed as antioxidants in a mineral oil lubricant by potentiometric determination of the peroxide value. CDs from tea wastes and GCDs exhibited good antioxidant properties both in aqueous and oil media. Possible mechanisms, such as C-addition to double bonds, H-abstraction and SOMO-CDs conduction band interaction, were proposed for the CDs radical scavenging activity. CDs from natural sources open new application pathways as antioxidant green additives.

Highlights

The emergence of carbon dots (CDs) has attracted much attention due to their unique luminescent properties, their chemical stability, their low toxicity and low environmental hazard
Citric acid/glutathione CDs, as representative of CDs obtained from small molecules were produced by hydrothermal synthesis
The antioxidant properties of all the CDs obtained were determined by DPPH, which compared favorably with those standard compounds such as ascorbic acid and vitamin E and with those of CDs obtained from raw biomaterials

Summary

Introduction

The emergence of carbon dots (CDs) has attracted much attention due to their unique luminescent properties, their chemical stability, their low toxicity and low environmental hazard. A broad range of technological applications such as optical sensing [1], bioimaging [2], tribology [3] or photocatalysis [4], among others, have been extensively explored. Due to their ability for scavenging reactive oxygen species, CDs demonstrate significant potential, for biological applications [5,6,7]. The method commonly used to prepare these CDs is the hydrothermal (HT) synthesis

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