Single-step synthesized carbon quantum dots from Centella asiatica hairy roots: Photoluminescent, biocompatibility, antibacterial and anticancer activity

Abstract

Medicinal plant-derived carbon quantum dots (CQDs) are emerging as promising nanomaterials with diverse biomedical applications and favorable biocompatibility profiles. In a novel approach, this study reports for the first time the synthesis of CQDs from transgenic hairy roots of Centella asiatica , carrying the Arabidopsis thaliana squalene synthase gene (At-SS1cDNA) as a sustainable and scalable precursor source. The optical characteristics were described using UV-Vis and photoluminescence spectroscopies, while their chemical and structural properties were examined using, Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), Zeta potential analysis, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), and Transmission electron microscopy (TEM). According to the results, the synthesized CQDs were uniformly dispersed spherical nanoparticles with a mean diameter of 1.07 ± 0.2 nm. XRD revealed the crystalline graphitic carbon phases, mixed with amorphous regions. FTIR analysis identified hydroxyl, carbonyl, carboxyl, and amino groups, as the most dominant functional entities present on the CQDs’ surface. The biological properties of CQDs synthesized from C. asiatica hairy roots were significantly superior, compaed to those from its methanolic and aqueous extracts. CQDs exhibited high antioxidant activity, comparable to trolax, as a standard reference. CQDs displayed superior antibacterial efficacy, particularly against Staphylococcus aureus , having an minimum inhibitory concentration (MIC) of 0.25 mg/mL. MTT assay showed a selectivity index of 13.87 for CQDs, indicating substantial selectivity towards cancer cells, rather than normal cell. The hemolysis test demonstrated that CQDs remained well below the 5 % cytocompatibility threshold across all concentrations, indicating high biocompatibility with minimal hemolytic effects. These findings suggest that CQDs produced sustainably from C. asiatica hairy roots, hold considerable promise for biomedical applications. • Carbon quantum dots were synthesized from Centella asiatica hairy roots for the first time. • Green-synthesized Carbon quantum dots possessed an average diameter of 1.07 ± 0.22 nm. • Carbon quantum dots exhibited a high IC50 of 14,697.9 µg/mL on HDF cells. • The hemolysis assay confirmed high biocompatibility of the synthesized Carbon quantum dots. • Synthesized Carbon quantum dots show promise for therapeutic and biomedical applications.

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