What is it about?
Carbon dots (CDots) are tiny carbon-based nanoparticles (NPs) that are less than 10 nanometers in diameter. They are also known as carbon quantum dots or fluorescent carbon nanoparticles. They have unique optical and electronic properties, including strong fluorescence, chemical stability, low toxicity, and high water solubility. CDots can be synthesized from various carbon sources, and their surface can be modified to confer additional properties and widen their range of potential applications. Selenium (Se) has attracted significant biomedical interest. The key for biomedical applications is that Se can act as both an oxidant and a reductant. This dual nature of Se has found application in cancer, and systems containing Se have been proposed as radioprotectors and anticancer drugs. However, the therapeutic window of Se is narrow, and it depends on dose and formulation. Se nanoparticles (SeNPs) are promising medical materials due to their chemotherapeutic characteristics and low toxicity. In fact, the use of nanoparticles in cancer (i.e., nanooncology) is a reality today, with several therapeutic NP-systems already approved and others under clinical investigation. Because they are biocompatible and have low toxicity, CDots are a good platform for biomedical applications like bioimaging and drug delivery.They can also target specific cells and tissues. In this context, the functionalization of CDots with Se is a new approach to deliver Se to the cells, with important physiological implications that may have pharmacological implications. We demonstrate that CDots bearing selenocyanate (a chemical group containing Se) act as antioxidant with the ability to neutralize peroxides, but also as an oxidant promoting the death in cells with low levels of antioxidants, as it is the case of some tumoral cells.
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Why is it important?
Nanoscale materials have found application in Nanomedicine, an emerging branch of medicine that seeks to apply nanotechnology to the prevention, diagnosis, and treatment of diseases. Nanomaterials present advantages over conventional drugs since their properties can be tuned to overcome physical barriers for drug delivery (i.e., those smaller than 50 nm can easily enter into most cells, while those smaller than 20 nm are extravasated from blood vessels) or to enhance energy absorption and re-radiation to create new therapeutics that disrupt tissues, such as hyperthermia or laser ablation, or for tumor imaging. In this context, our work demonstrates that CDots are suitable platforms that can be transformed into a Se-bearing nanomaterial (CD-SeCN) that exhibits glutathione peroxidase-like activity and cytotoxicity. The effect on the cell depends on the content of glutathione, a physiological antioxidant whose concentration is altered in tumor cells, leading to cell death in those with depleted levels. These results support the pharmacological potential of CD-SeCN in cancers with low levels of intracellular GSH.
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This page is a summary of: Turning carbon dots into selenium bearing nanoplatforms with in vitro GPx-like activity and pro-oxidant activity, Nano Research, March 2023, Springer Science + Business Media, DOI: 10.1007/s12274-023-5442-3.
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Acid anhydride coated carbon nanodots: activated platforms for engineering clicked (bio)nanoconstructs
Activated carbon nanodots functionalized with acid anhydride groups (AA-CNDs) are prepared by one-pot water-free green thermolysis of citric acid. As a proof of concept of their capabilities as appealing and versatile platforms for accessing engineering nanoconstructs, the as-prepared AA-CNDs have been reacted to yield clickable CNDs. Their click bioconjugation with relevant recognizable complementary clickable sugars has led to multivalent CND-based glyconanoparticles that are non-toxic and biorecognizable. The accessibility and intrinsic reactivity of AA-CNDs expand the current toolbox of covalent surface grafting methodologies and provide a wide range of potential applications for engineering (bio)nanoconstructs.
Amphiphilic-like carbon dots as antitumoral drug vehicles and phototherapeutical agents
Water-insoluble carbon dots are recognized as promising materials, although their applications in nanomedicine are rarely explored, despite their lipophilic character and foreseen compatibility with biological membranes. In this article, we exploit the anhydride functionalization of carbon dots obtained by thermolysis of citric acid to synthesize amphiphilic-like carbon dots (LCDs) by reaction with alkyl amines. A differential feature of this approach is that the hydrophobicity of LCDs is a balance between the ionization of the carboxylic groups resulting from the reaction and the hydrophobicity from the grafted amines. The alkyl chains allow LCDs to entrap hydrophobic molecules and the ionization of the carboxylic groups increases the hydrosolubility, permitting the transfer between organic and aqueous phases. The biomedical interest of these features is illustrated by analyzing the application of LCDs as carriers of the drug campothecin and their evaluation on a battery of cancer cell lines, as well as the transformation of LCDs into a phototherapeutic agent by the formation of a complex with IR780 dye. Results demonstrate that LCDs behave as nanocarriers in a manner that resembles other supramolecular hosts with two differential features: (i) the length of the alkyl chains determines the size of the hosted guest, and (ii) the hydrosolubility of the complex can be modulated by pH.
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