Green synthesis of fluorescent carbon dots from spices for in vitro imaging and tumour cell growth inhibition

Abstract

Carbon dots have demonstrated great potential as luminescent nanoparticles in bioapplications. Although such nanoparticles appear to exhibit low toxicity compared to other metal luminescent nanomaterials, today we know that the toxicity of carbon dots (C-dots) strongly depends on the protocol of fabrication. In this work, aqueous fluorescent C-dots have been synthesized from cinnamon, red chilli, turmeric and black pepper, by a one-pot green hydrothermal method. The synthesized C-dots were firstly characterized by means of UV–vis, fluorescence, Fourier transform infrared and Raman spectroscopy, dynamic light scattering and transmission electron microscopy. The optical performance showed an outstanding ability for imaging purposes, with quantum yields up to 43.6%. Thus, the cytotoxicity of the above mentioned spice-derived C-dots was evaluated in vitro in human glioblastoma cells (LN-229 cancer cell line) and in human kidney cells (HK-2 non-cancerous cell line). Bioimaging and viability studies were performed with different C-dot concentrations from 0.1 to 2 mg·mL−1, exhibiting a higher uptake of C-dots in the cancer cultures compared to the non-cancerous cells. Results showed that the spice-derived C-dots inhibited cell viability dose-dependently after a 24 h incubation period, displaying a higher toxicity in LN-229, than in HK-2 cells. As a control, C-dots synthesized from citric acid did not show any significant toxicity in either cancerous or non-cancerous cells, implying that the tumour cell growth inhibition properties observed in the spice-derived C-dots can be attributed to the starting material employed for their fabrication. These results evidence that functional groups in the surface of the C-dots might be responsible for the selective cytotoxicity, as suggested by the presence of piperine in the surface of black pepper C-dots analysed by ESI-QTOF-MS.

Synthesis of ginsenoside Re-based carbon dots applied for bioimaging and effective inhibition of cancer cells

“…Recently, researchers have found that some of the CDs using green carbon sources including green tea, garlic, pepper, lysine and so on or drugs such as aspirin may get both fluorescent characters and bioactivities such as anticancer, antioxidant and anti-inflammatory effects. [30][31][32][33][34] These attractive CDs can show significant bioactivities when they are used for tracing and bioimaging in vivo or vitro. It is a fascinating challenge to form the CDs having both biological activities and fluorescent property after high temperature hydrothermal synthesis.…”

Carbon quantum dots and their biomedical and therapeutic applications: a review

“…Several researchers have successfully used the CQDs for in vitro bioimaging. 52,[101][102][103][104][105][106][107][108][109][110][111][112][113] In several applications, the QDs are preferred to organic dyes and uorescent proteins due to the enhanced brightness, photostability, imaging sensitivity, and good resistance to metabolic degradation. 114 Semiconductor QDs such as CdSe with their core-shell structure (e.g.…”

NanoRefinery of carbonaceous nanomaterials: Complementing dairy manure gasification and their applications in cellular imaging and heavy metal sensing

“…transform different substrates such as pollen, spices and coffee beans (D'Angelis do ES et al, 2015;Essner et al, 2016;Vasimalai et al, 2018;Zhang et al, 2018). However, converting biomass into biochar with the sole aim of making advanced nanomaterials is a high energy cost process that misses the opportunity for bioenergy production.…”