Search

Herein, a facile, green and eco‐friendly approach has been applied for the synthesis of fluorescent green‐blue carbon dots (GB‐CDs) through the one‐pot hydrothermal treatment of Artocarpus lakoocha seeds for the first time and entirely characterized via a variety of instrumental techniques like fluorescent spectroscopy, Transmission Electron Microscopy (TEM), X‐Ray Photoelectron Spectra (XPS), X‐Ray diffraction (XRD) and Fourier Transform Infra‐red (FTIR) analysis. The as‐prepared GB‐CDs displayed high fluorescent quantum yield (QY) up to 38.5% and high photostability based on which GB‐CDs were successfully applied as a sensitive nanoprobe for the detection of Fe3+ ion. The sensing of Fe3+ shows a linear range from 2 to 6 μM and the limit of detection was found to be 0.62 μM. The sensing of Fe3+ was further investigated in the bona fide sample like river water and human blood serum. In addition, to explore the potential application, MTT assay was carried out on SH‐SY5Y neuroblastoma cells. The results showed negligible cytotoxicity as well as high cell viability, which revealed that GB‐CDs could be utilized as a fluorescent probe in living cells. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • This is first report of synthesis of fluorescent carbon dots from Dunaliella salina. • A-NPCDs were used as fluorescent probe for selective detection of Hg (II), Cr (VI). • A-NPCDs offer excellent multi-color cell imaging. • Limit of detection for Cr (VI) and Hg (II) were 0.018 μM. • MTT assay showed that carbon dots were biocompatible and slightly cytotoxic. Abstract The impact of hazardous chemicals and toxic metal ions in the environment played havoc to the ecosystem. In the present work green chemistry approach was applied for one-step hydrothermal synthesis of nitrogen, phosphorus dual doped carbon dots, utilizing green precursor i.e, biomass of halophilic microalgae Dunaliella salina (algal derived nitrogen phosphorous carbon dots i.e A-NPCDs). Synthesized A-NPCDs were characterized through TEM, FT-IR, P-XRD, DLS and XPS. It showed appreciable optical properties with significant fluorescence quantum yield (8%)and exhibited blue color under UV – light (λ ex = 365 nm). A-NPCDs acted as fluorescent turn off sensor for toxic metal ion such as Hg (II) and Cr (VI) with good selectivity and sensitivity. Interestingly, ANPCDs detected Cr (VI) up to 0.018μM which was below the permissible level of Cr (VI) in drinking water. Such sensing resulted because of combination of inner filter effect and dynamic quenching mechanism. Moreover, it also showed good selectivity (0.018μM) for Hg (II) via dynamic quenching mechanism. MTT assay of A-NPCDs on HEK-293 cell line showed biocompatibility with negligible cytotoxicity. Therefore, these were successfully employed for live cell imaging and intracellular detection of Hg (II) and Cr (VI) in HEK-293 cell line. Thus, green synthesized A-NPCDs may be a good alternative for chemically derived CDs in intracellular detection of Hg (II) and Cr (VI) of a complex biological environment. [ABSTRACT FROM AUTHOR]

A novel hybrid fluorophore (FHPY) has been synthesized based on a condensation reaction of two standard fluorescent hydrophobic–hydrophilic molecules, viz. pyrene and fluorescein, with an objective to tune the aggregation-induced emission (AIE) along with the morphology. Owing to the distinct photophysical properties of pyrene and fluorescein, the hybrid FHPY dramatically exhibits a fluorescence change from colourless to yellow-green via a blue colour upon varying the volume fraction of water (poor solvent) in methanol (good solvent). FHPY has exhibited not only AIE, but also an outstanding quantum yield (ΦF) of 97% at a 70% water fraction in methanol (70 : 30, v/v). We attribute the reason behind the tuning of the AIE and quantum yield to the opening of the lactam ring of fluorescein as well as to the amassing of hydrophobic pyrene at a certain water fraction. The mechanism involved in the AIE has been well supported by detailed UV-vis, fluorescence, lifetime, SEM, AFM, DFT, PXRD and 1H NMR experiments. In addition, FHPY serves as a good candidate for the live cell imaging of HeLa cells. [ABSTRACT FROM AUTHOR]

Nitrogen doped carbon quantum dots (N-CQDs) was efficiently synthesized by one pot hydrothermal method and effectively used for on-off-on sensing of Hg2+ and GSH in pure aqueous medium and live cell imaging application on MCF-7 cancer cell line. • One step hydrothermal synthesis of N-CQDs via simple and cost efficient precursors with fluorescence quantum yield of 41%. • N-CQDs act as fluorescent probe for on-off-on detection of Hg2+ and GSH with good selectivity and sensitivity. • The MTT assay of N-CQDs on MCF-7 cancer cell line showed negligible toxicity and excellent biocompatibility. • The cell imaging result showed intracellular internalization of N-CQDs in MCF-7 cell in dichromic region (blue & green). • The N-CQDs could be utilized for multifunctional applications such as sensing of Hg2+, biothiol and cell imaging agent. The present work describes the synthesis of N-CQDs via one step hydrothermal methods. The synthesized N-CQDs was fully characterized by TEM, P-XRD, FT-IR, XPS and Zeta sizer. It exhibited excitation independent emission behaviour with fluorescent quantum yield of 41% respect to quinine sulphate standard. The excellent optical properties of N-CQDs made it fluorescent probe for turn off detection of toxic heavy metal ion Hg2+ with good selectivity and sensitivity. The limit of detection was found to be 0.08 μM with correlation coefficient (R2 = 0.992). After addition of various reducing agent such as amino acid, EDTA and GSH in the quenched solution of N-CQDs + Hg2+, the fluorescence property was selectively recovered in the presence of GSH and hence the quenched solution further acts as selective turn on sensing of GSH up to lower limit of 2.0 μM with correlation coefficient (R2 = 0.996). The on-off-on sensing behaviour of N-CQDs was utilized for the implication of logic gate in absence and presence of Hg2+ and GSH to construct the molecular switches. The MTT assay of N-CQDs was performed on MCF-7 cancer cell line to check their applicability in biological system and the result showed negligible cytotoxicity and good permeability. The cell imaging on MCF-7 cells visualized in dichromic region (blue and green). Therefore, it could be smart material for sensing of heavy toxic metal as well as cell imaging application. [ABSTRACT FROM AUTHOR]