Aggregation behavior of fullerenes in aqueous solutions: a capillary electrophoresis and asymmetric flow field-flow fractionation study

Surfactant-mediated mobility of carbon dots in saturated soil: comparison between anionic and cationic surfactants

Understanding the mobility, retention, and fate of carbon dots (CDs) is critical for the risk management of this emerging carbon material. However, the influences of surfactants on CDs' transport through subsurface media are still poorly understood. Herein, column experiments were conducted to explore the different influences of an anionic surfactant, sodium dodecylbenzene sulfonate (SDBS), and a cationic surfactant, cetyltrimethylammonium bromide (CTAB), on the CDs' transport in water-saturated soil. In the Na⁺ background electrolyte, both surfactants facilitated the transport of CDs at pH 7.0. The trend stemmed from steric hindrance, a decline in the straining effect, and competitive deposition between CDs and surfactant molecules. Additionally, SDBS increased the electrostatic repulsion of CDs and soil. Interestingly, in the divalent cation background electrolytes (i.e., Ca²⁺ or Cu²⁺), SDBS suppressed CDs' mobility, whereas CTAB had the opposite effect. The transport-inhibited effect of SDBS was mainly due to anionic surfactant ion (DBS^-) precipitation with metal cations and the formation of adsorbed SDBS-Cu²⁺/Ca²⁺-CDs complexes. The enhanced effect of CTAB resulted from the CTAB coating on soil grains, which suppressed the cation bridging between CDs and soil. Furthermore, the magnitude of the SDBS promotion effect was pH-dependent. Surprisingly, CTAB could inhibit CDs' mobility at pH 9.0, owing to the binding cationic surfactant's strong hydrophobicity effect on the soil surface. Moreover, the experimental breakthrough curves of CDs were well described using a two-site transport model. Overall, the observations obtained from this study shed light on the relative mobility of CDs with different surfactants in typical groundwater conditions.

Fullerene as a doxorubicin nanotransporter for targeted breast cancer therapy: Capillary electrophoresis analysis

The clinical use of doxorubicin (DOX) is limited by dose-related cardiomyopathy, which becomes more prevalent with increasing cumulative doses of the drug. Complexes of fullerene with DOX were designed and studied using biophysical methods. The ability of DOX to release from fullerene at different pHs was analyzed. It has been shown that the size of the fullerene-DOX complexes was ∼280 nm. The zeta potential for fullerene was -30 mV, for DOX -8 mV, and for fullerene-DOX conjugates -24 mV. Drug release was studied by CE with LIF detection. When fullerene-DOX conjugates were separated in a pH 7.5 buffer, 43% of all DOX signals were derived from free DOX, with the signal increasing as pH decreased. At pH 5.25, all DOX had been released and 100% of the signal was derived from free DOX. The release of DOX from complexes with fullerene at lower pH can be used in targeted antineoplastic therapy, resulting in lower toxicity for less acidic non-target tissue.

Metabolic Responses of Mytilus galloprovincialis to Fullerenes in Mesocosm Exposure Experiments

In this study, Mediterranean mussels (Mytilus galloprovincialis) were exposed through the diet to fullerene soot at three concentrations in parallel to a control group. Their metabolomics response was assessed by high-performance liquid chromatography coupled to high-resolution mass spectrometry (HPLC-HRMS). The experiments were conducted in marine mesocosms, during 35 days (7 days of acclimatization, 21 days of exposure, and 7 days of depuration). Real conditions were emulated in terms of physicochemical conditions of the habitat. Results confirmed the bioaccumulation of fullerenes, and the metabolome of the exposed organisms revealed significant differences in the concentrations of seven free amino acids in comparison to the control group. An increase in small nonpolar amino acids (e.g., alanine) and branched chain amino acids (leucine and isoleucine) were observed. Also, glutamine concentrations decreased significantly, suggesting the activation of facultative anaerobic energy metabolism. Branched chain amino acids, such as leucine and isoleucine, followed the opposite trend after the highest level of exposure, which can imply hormesis effects. Other significant differences were observed on lipids content, such as the general increase of free fatty acids, i.e., long-chain fatty acids (lauric, myristic, and palmitic acids) when the concentration of exposure was increased. These results were consistent with hypoxia and oxidative stress.