White light-emitting, biocompatible, water-soluble metallic magnesium nanoclusters for bioimaging applications.

Ultra-small (1.6 nm), water-soluble, white light-emitting (WLE), highly stable (∼8 months) BSA templated metallic (Mg0) nanoclusters (fluorescent magnesium nanoclusters = FMNCs) is developed using the green and facile route. Synthesis was facilitated by the reduction of magnesium salt, where template bovine serum albumin is utilized as a reducing agent and ascorbic acid act as a capping agent to impart stability in water, thereby obtaining stabilized Mg0nanoclusters In solution, stabilized Mg0nanoclusters produce white light (450-620 nm with FWHM ∼120 nm) upon 366 nm light excitation. This white light emission was found to have a CIE coordinate of 0.30, 0.33 [pure white light CIE (0.33, 0.33)]. Taking advantage of WLE and ultrasmall size, FMNCs were used forin vitrofluorescence imaging of HaCaT cell lines, yielding blue (τ= 2.94 ns, with a relative of QY = 1.2 % w.r.t QS), green (τ= 3.07 ns; relative quantum yield of 4.6% w.r.t R6G) and red (τ= 0.3 ns) images. Further, incubation of FMNCs with HEK293 (Human embryonic kidney cell) and cancerous MDA-MB-231 (Breast cancer cell line) human cell lines yielded 100 % cell viability. Current work is envisioned to contribute significantly in the area of science, engineering, and nanomedicine.

Forecast of Phase Diagram for the Synthesis of a Complex for the Detection of Cr6+ Ions.

A new organic complex (ANNBA) was synthesized using the solvent-free, solid-state reaction involving anthranilamide (AN)-m-nitrobenzoic acid (NBA). The established phase diagram specifies the formation of a complex in a 1:1 stoichiometric ratio which melts congruently at 142 °C. The diagram also infers the formation of two eutectics, E1 and E2, on either side of the complex with their respective melting at 118 and 106 °C. The stability and novelty of the synthesized complex was confirmed by differential scanning calorimetry, powder X-ray diffraction, and spectroscopic FTIR, 1H, and 13C NMR studies. The significant thermodynamic parameters such as the heat of mixing, the entropy of fusion, the roughness parameter, the interfacial energy, and excess thermodynamic functions have been studied. The novel complex (ANNBA) material displayed intense fluorescent emission as compared to the parent and the other well-known fluorescent organic material "pyrene." The influence of solvent's polarity on the absorption and emission of the complex has been studied in different solvents. Herein, we have displayed remarkable affinity of the complex toward hexavalent chromium ions in water, affecting its fluorescent property. We have deployed the synthesized complex as a turn-off fluorescent sensor to detect the most hazardous hexavalent chromium ions in water for the first time.

Correction: Development of ultrasensitive and As(III)-selective upconverting (NaYF4:Yb3+,Er3+) platform.

Correction for 'Development of ultrasensitive and As(III)-selective upconverting (NaYF4:Yb3+,Er3+) platform' by Suman Duhan et al., Analyst, 2020, 145, 6378-6387, DOI: 10.1039/D0AN00717J.

Color removal from model dye effluent using PVA-GA hydrogel beads.

A low cost polyvinyl alcohol-glutaraldehyde cross-linked hydrogel beads were prepared and used for color removal from model industrial effluent containing Congo Red dye, using adsorption technique. The adsorption studies were performed using batch and fixed-bed reactor. Developed adsorbent, achieved adsorption capacity as high as ~34 mg of dye per gram of bead (condition: pH 6 and 45 °C). These beads were re-used for 7 times (many more runs possible) to remove the color from model dye effluent, without much loss in removal efficiency. Batch studies revealed a multi-layer adsorption governed by Harkins Jura model. Whereas the adsorption kinetics followed fractal like pseudo second order model, controlled by intraparticle diffusion phenomena. The fixed bed studies revealed steeper break through curves during adsorption operation when high dye influent rates and low bed height were used. This behaviour by the fixed bed reactor was best explained by the Thomas mathematical model. Studies further demonstrated that an external and internal mass diffusion become no more rate limiting during these experiments.

Development of ultrasensitive and As(III)-selective upconverting (NaYF4:Yb3+,Er3+) platform.

The development of a sensitive α-NaYF4:Yb3+,Er3+ solid-phase upconverting platform (UCP) was realized using Moringa oleifera leaf extract for selective detection of the trivalent arsenic ion [As(iii)] contamination in drinking water. The presence of polyphenols in the leaf extract were shown to induce luminescence resonance transfer (LRET), thereby diminishing the Er3+ emission (red and green band) when activated by 980 nm excitation. However, the addition of As(iii) species interrupted the LRET process and restored the emissions proportionately. This feature allowed the platform to selectively detect arsenic pollution in water below the safe limit of 10 ppt. The uniqueness of UCP lies in monitoring the As(iii) contamination in samples containing heavy ions (Cd2+ and Hg2+) also, without an apparent effect on the signal reproducibility. The UCP was also found to be insensitive to other interfering ions including Pb2+, H2PO4-, F-, Cl-, Ca2+, Mg2+, Sn2+, Cr6+, Fe2+ and Co2+, if present.

Development of luminescent atacamite nanoclusters for bioimaging and photothermal applications.

Fluorescent atacamite nanoclusters (FANCs) have been developed and modified with silica for Drosophila salivary gland tissue imaging and photothermally induced cell death of osteosarcoma MG-63 cells. FANCs were synthesized with Moringa oleifera leaf extract without using any hazardous reducing and external capping agents. FANC was further used to evaluate light absorption, fluorescence emission, band gap, and magnetic properties as the first report on such nanoclusters. Upon excitation with a 350 nm light source, FANCs exhibited fluorescence at 460 nm, with a relative quantum yield of 0.3%. Besides, silica-encapsulated fluorescent atacamite nanoclusters (SEFANC) manifested remarkable improvement in emission, quantum yield (1.7%), shelf-life (15 d), biocompatibility, and photostability. Concomitantly, it has also increased the absorption in the near-infrared region and demonstrated high heat generation potential (42 °C → 50 °C). The above results suggest that FANC can be a potential candidate in the area of nanomedicine for a number of applications such as bioimaging, photothermal therapy, etc.