Shaddock peel-derived N-doped carbon quantum dots coupled with ultrathin BiOBr square nanosheets with boosted visible light response for high-efficiency photodegradation of RhB

In the present work, we constructed a serials of novel shaddock peel-derived N-doped carbon quantum dots (NCQDs) coupled with BiOBr composites. The result showed that the as-synthesized BiOBr (BOB) was composed of ultrathin square nanosheets and flower-like structure, and NCQDs were uniformly dispersed on the surface of BiOBr. Furthermore, the BOB@NCQDs-5 with optimal NCQDs content displayed the top-flight photodegradation efficiency with ca. 99% of removal rate within 20 min under visible light and possessed excellent recyclability and photostability after 5 cycles. The reason was attributed to relatively large BET surface area, the narrow energy gap, inhibited recombination of charge carriers and excellent photoelectrochemical performances. Meanwhile, the improved photodegradation mechanism and possible reaction pathways were also elucidated in detail. On this basis, the study opens a novel perspective to obtain a highly efficient photocatalyst for practical environment remediation.

A novel multifunctional NCQDs-based injectable self-crosslinking and in situ forming hydrogel as an innovative stimuli responsive smart drug delivery system for cancer therapy

In this work, we offer an easy approach to develop a novel injectable, pH sensitive and in situ smart drug delivery system for use in cancer treatments. The developed hydrogels containing nitrogen doped carbon quantum dots (NCQD), doxorubicin (Dox) and hydroxyapatite (HA) were obtained by in situ self-crosslinking. Characterization of the synthesized nanomaterials, interactions between NCQD/Dox/HA hydrogel structure were carried out by TEM, FESEM, EDS, FTIR, XPS, XRD, Zeta potential, DLS, UV-Vis, SEM, gelation time, injectability and DIST measurements. In addition, antibacterial evaluation which was performed against Staphylococcus aureus realized that HA compound significantly increased the antibacterial activity of the hybrid hydrogel. The anticancer drug release to the tumor cell microenvironment with a pH of 5.5 was found to be higher compared to the release in the normal physiological range of pH 6.5 and 7.4. MTT and live/dead assays were also performed using L929 fibroblastic cell lines to investigate the cytotoxic behavior of NCQDs, and NCQDs/Dox/HA hydrogels. Furthermore, the NCQDs/Dox/HA hydrogel could transport Dox within a MCF-7 cancerous cell at specifically acidic pH. Additionally, imaging of cell line was observed using NCQDs and their use in imaging applications and multicolor features in the living cell system were evaluated. The overall study showed that in situ formed NCQDs/Dox/HA hydrogel represented a novel and multifunctional smart injectable controlled-release drug delivery system with great potential, which may be considered as an attractive minimal invasive smart material for future intelligent delivery of chemotherapeutic drug and disease therapy applications.

Nitrogen-doped carbon quantum dots conjugated isoreticular metal-organic framework-3 particles based luminescent probe for selective sensing of trinitrotoluene explosive

Amine group-containing isoreticular metal-organic framework (IRMOF-3) particles are utilized for the first time as a trinitrotoluene (TNT) sensing material. IRMOF-3 particles are synthesized using zinc nitrate as a metal precursor and 2-amino-1,4-benzenedicarboxylic acid as a linker. The nitrogen-doped carbon quantum dots (NCQDs) are synthesized from citric acid and ethylenediamine as carbon and nitrogen precursor, respectively. The NCQDs are conjugated with IRMOF-3 particles as IRMOF-3/NCQDs. The TEM micrograph revealed the average size of IRMOF-3 particles to be 363.66 nm. The photoluminescence emission intensity of IRMOF-3 particles at λ_em 430 nm is highly increased in the presence of NCQDs (λ_ex 330 nm). Both the as-synthesized IRMOF-3 and IRMOF-3/NCQD particles are explored for TNT detection to compare the effect of NCQDs on the IRMOF-3 particle surface. Lower limit of detection (7.5 × 10^-8 M) and higher Stern-Volmer constant (4.46 × 10⁶ M^-1) are achieved by IRMOF-3/NCQD particles. The association constant also increased from 5.3 × 10⁴ to 2.78 × 10⁶ M^-1 after the conjugation of IRMOF-3 particles with NCQDs. Moreover, enhanced selectivity for TNT over trinitrophenol is achieved using the IRMOF-3/NCQD particles. Graphical Abstract.

Detection of Malachite Green in Water Using Edge Excited Label Free Fluorescent Probe NCQDs

The fluorescent properties of nitrogen doped carbon quantum dots (NCQDs) prepared through microwave assisted green method has been used as label free fluorescent probe for selective and sensitive detection of malachite green (MG) in water. The optical responses revealed that the NCQDs are highly stable and have good fluorescent quantum yield. The NCQDs were used to detect the Malchite Green in Mili Q water. Reduction in the fluorescence response was monitored in the range 17.12-128.43 μM of MG dissolved in Mili Q water. Linear response was observed in the range, 10-80 μM. The calculated value of limit of detection is 5.16 μM and the sensitivity is (0.03536 ± 0.00001) μM^-1. The future application of this work is that it can be employed to detect MG in the tap water and other natural sources of water.