We propose a one-pot microwave-assisted pyrolysis method for fabrication of magnetofluorescent carbon quantum dots (MFCQDs), using a combination of waste crab shell and three different transition-metal ions, Gd, Mn, and Eu, referred to as Gd@CQDs, Mn@CQDs, and Eu@CQDs, respectively. Chitin from waste crab shell acted not only as a carbon source but also as a chelating ligand to form complexes with transition-metal ions. Gd@CQDs exhibited a high r relaxivity of 4.78 mM·s and a low r/r ratio of 1.33, suggesting that they show excellent potential as a T contrast agent. Mn@CQDs and Eu@CQDs showed high r relaxivity values of 140.7 and 28.32 mM·s, respectively, suggesting their potential for use as T contrast agents. Further conjugation of Gd@CQDs with folic acid (FA) enabled specific targeting to folate receptor-positive HeLa cells, as confirmed via in vitro magnetic resonance and fluorescence imaging. Doxorubicin (DOX) was selected as a model drug for conjugation with FA-Gd@CQDs. The as-prepared nanocomposites showed significantly higher cytotoxicity toward HeLa cells than free DOX. No apparent cytotoxicity was observed in vivo (zebrafish embryos) or in vitro (cell viability), suggesting that MFCQDs show potential for development as diagnostic probes or theranostic agents.

No abstract

Recently, synthesis, characterization, and application of carbon dots have received much attention. Natural products are the effectual carbon precursors to synthesize carbon dots with fascinating chemical and physical properties. In this study, the fluorescent sensor of carbon dots derived from cranberry beans without any functionalization and modification was developed. The carbon dots were prepared with a cheap, facile, and green carbon precursor through a hydrothermal treatment method. The synthetic process was toxic chemical-free, convenient, and environmentally friendly. To find the optimized synthetic conditions, the temperature, heating time duration, and carbon precursor weight were evaluated. The prepared carbon dots were characterized by UV light, transmission electron microscopy, Raman, Fourier transform infrared, UV–vis, and fluorescence spectroscopy. The resulting carbon dots exhibit stable fluorescence with a quantum yield of approximately 10.85%. The carbon dots emitted the broad fluorescence emission range between 410 and 540 nm by changing the excitation wavelength and were used for the detection of Fe3+ ions at the excitation of 380 nm. It is found that Fe3+ ions induced the fluorescence intensity quenching of the carbon dots stronger than other heavy metals and the Fe3+ ion detection can be achieved within 3 min. Spectroscopic data showed that the obtained carbon dots can detect Fe3+ ions within the wide concentration range of 30–600 μM with 9.55 μM detection limit.

No abstract

No abstract

No abstract

The formation and characterization of shrimp shell-derived CaO nano-plates with antibacterial activity have been demonstrated in this communication.

In this work, manganese‐doped carbon quantum dots (Mn‐CQDs) have been synthesized through a one‐pot hydrothermal method by using waste green tea. The Mn2+ dopants were introduced to impart magnetic resonance capability. Upon optimization of the experimental conditions, magnetofluorescent Mn‐CQDs exhibit an excitation‐dependent blue emission. The abundant functional groups on Mn‐CQDs not only promote water solubility but also allow straightforward functionalization with amine groups. The amine‐terminated Mn‐CQDs were then subsequently conjugated to folic acid (FA) and chlorin e6 (Ce6) to obtain the Mn‐CQDs@FA/Ce6 magnetofluorescent photodynamic therapy (PDT) agent. in vitro studies using three different cells indicated specific targeting of Mn‐CQDs@FA/Ce6 to the overexpressing folate receptor human epithelial carcinoma cell line (HeLa) cancer cells. Furthermore, Mn‐CQDs@FA/Ce6 enhanced magnetic resonance imaging (MRI) signal with an r2/r1 ratio of 5.77. Favorably, by using the Mn‐CQDs@FA delivery system, active Ce6 can reach the cellular interior while its red fluorescence (FL) and reactive oxygen species generation can be retained, as has been verified by confocal microscopy. in vitro cell viability studies verified the biocompatibility of Mn‐CQDs@FA/Ce6 nanohybrid with no significant toxicity up to 500 ppm while PDT treatment with 5 min irradiation (671 nm, 1 W cm−2) was effective in killing >90% of cells. The light‐triggered Mn‐CQDs@FA/Ce6 multifunctional hybrid can serve as a dual‐modal FL/MRI probe and as an efficient PDT agent to detect and eradicate cancer cells remotely.