Nitrogen-doped carbon dots: Recent developments in its fluorescent sensor applications

Doped carbon dots have attracted great attention from researchers across disciplines because of their unique characteristics, such as their low toxicity, physiochemical stability, photostability, and outstanding biocompatibility. Nitrogen is one of the most commonly used elements for doping because of its sizeable atomic radius, strong electronegativity, abundance, and availability of electrons. This distinguishes them from other atoms and allows them to perform distinctive roles in various applications. Here, we have reviewed the most current breakthroughs in nitrogen-doped CDs (N-CDs) for fluorescent sensor applications in the last five years. The first section of the article addresses several synthetic and sustainable ways of making N-CDs. Next, we briefly reviewed the fluorescent features of N-CDs and their sensing mechanism. Furthermore, we have thoroughly reviewed their fluorescent sensor applications as sensors for cations, anions, small molecules, enzymes, antibiotics, pathogens, explosives, and pesticides. Finally, we have discussed the N-CDs' potential future as primary research and how that may be used. We hope that this study will contribute to a better understanding of the principles of N-CDs and the sensory applications that they can serve.

Vapour-Phase Selective Hydrogenation of γ-Valerolactone to 2-Methyltetrahydrofuran Biofuel over Silica-Supported Copper Catalysts

2-Methyltetrahydrofuran (MTHF) is a desirable biomass-based platform chemical with excellent potential as an ideal biofuel, green solvent, and raw material for synthesizing downstream chemicals. In this work, a series of copper nanoparticles encapsulated on SiO₂ were prepared by the wet impregnation method and evaluated as efficient non-noble metal catalysts for the vapour-phase hydrogenation of γ-valerolactone (GVL) to MTHF in a fixed-bed reactor under mild reaction conditions. The obtained catalyst properties were determined by XRD, FE-SEM, TEM, UV-DRS, TPR, NH₃-TPD, N₂O decomposition and pore size distribution measurements. Meanwhile, the parameters/variables tuning their catalytic performance (activity, conversion, selectivity and stability) were examined. Various Cu loadings featured on the SiO₂ support are essential for tuning the catalytic activity. Among the catalysts tested, a 5 wt% Cu/SiO₂ catalyst showed a 97.2% MTHF selectivity with 71.9% GVL conversion, and showed a stability for 33 h time-on-stream, achieved at 260 °C and atmospheric pressure conditions. It was found that a huge dispersion of Cu metal in support, hydrogen activation ability, abundant acidic sites and surface area are all beneficial for improved MTHF selectivity.

Recent advances in biomass-derived platform chemicals to valeric acid synthesis

A perspective overview for levulinic acid and/or γ-valerolactone to valeric acid synthesis via thermocatalytic and electrocatalytic systems has been summarized.

Lignin to Value-added Chemical Synthesis

Background:

There is an increasing demand for innovation in petroleum system replacements. Towards this aim, lignocellulosic biomass is suggested as a possible sustainable source for the manufacturing of fuels and chemical production. This paper aims to investigate different kinds of β-O-4 lignin model compounds for the production of value-added chemicals in the presence of ionic liquids. Especially, cheap β-O-4 lignin model guaiacol glycerol ether (GGE) (Guaifenesin) is introduced to produce valuable chemicals and novel products.

Methods:

The research related to chemical depolymerization of lignocellulosic biomass activity is reviewed and an account of different methods such as thermal and microwave for the last 10 years is presented. So, this work provides an excellent background for academic research and it gives an efficient strategy for the manufacturing of novel value-added chemicals at an industrial scale.

Results:

The review concludes that ionic liquid microwave-assisted synthesis is a power-saving, cost-efficient, fast reaction, and clean way with high selectively and purity for the production of high-value chemicals rather than conventional heating. Guaiacol and catechol are some of these valuable chemicals produced from β-O-4 lignin model compounds with high demands and large industrial scale prospects.

Conclusion:

The β-O-4 lignin model compounds such as guaiacol glycerol ether (GGE) (Guaifenesin) are a good platform for developing food materials, perfumery, biorefinery, and pharmaceutical industry by ionic liquids-assisted lignin depolymerization method.

Study of Cobalt Doped GdAlO3 for Electrochemical Application

Background:

Nano perovskite-type structures as denoted by ABO3 (A= RE) have been popular targets of fundamental investigations since they exhibit a wide variety of physical properties depending upon the chemical composition, defects and small changes in atomic arrangements.

Methods:

GdAlO3: Co2+ (1, 3 &9 mol %) was synthesized using the solution combustion method by using stoichiometric quantities of gadolinium nitrate [Gd (NO3)3], aluminium nitrate (Al (NO3)2, and cobalt nitrate Co(NO3)2.

Results:

The morphology, structure and particle size of the prepared GdAlO3: Co2+ sample were characterized by transmission electron microscope (TEM) image. The Fourier transform infrared (FT-IR) spectral analysis confirmed that the as-prepared powder was in pure state. Electrochemical impedance measurements (EIS) of different GdAlO3: Co2+ samples were measured vs. Ag/AgCl in the frequency range of 1 Hz to 1 MHz with AC amplitude of 5 mV at steady-state which clearly indicated that Co2+ dopant is a successful doping material for the fabrication of supercapacitors.

CONCLUSION:

Electrochemical impedance measurements (EIS) of different GdAlO3: Co2+ samples were measured vs. Ag/AgCl in the frequency range of 1 Hz to 1 MHz with AC amplitude of 5 mV at steady-state which clearly indicated that Co2+ dopant is a successful doping material for the fabrication of supercapacitors. From a future perspective, we believe that GdAlO3: Co2+ composite material could be a promising electrode material for the fabrication of various sensors, supercapacitors and solar cells.

Combination of ZnO Nanoparticle with Marine Sponge Derived Dipeptide for Enhanced Anticancer Efficacy in Liver Cancer Cells and their Toxicity Evaluation on Embryonic Zebrafish

Background:

Nanomaterials-based cancer therapy plays a significant role in increasing the therapeutic efficiency of anticancer drugs, reducing side effects and targeted delivery of the drug payloads. The present study was aimed to enhance the anticancer effect of a novel dipeptide isolated from marine sponge-associated Bacillus pumilus AMK1 by formulating with Zinc oxide (ZnO) nanoparticles for the effective treatment against HepG2 liver cancer cells.

Methods:

ZnO nanoparticles were synthesized by chemical method and size of the nanoparticle was characterized by Scanning electron microscope, X-Ray diffraction and Fourier-transform infrared spectroscopy. Furthermore, ZnO nanoparticles were conjugated with the isolated dipeptide and evaluated for anticancer activity. In addition, distinct morphological changes were observed by performing apoptotic staining methods such as propidium iodide staining and acridine orange/ ethidium bromide staining. Furthermore, embryotoxic and teratogenic effects of conjugated dipeptide on the development of zebrafish embryo were investigated in this study.

Results:

It was observed that conjugated dipeptide showed enhanced cytotoxicity against HepG2 liver cancer cells without any toxic effect on normal liver cells. ZnO with dipeptide showed significant higher apoptosis of liver cancer cells, with around 19% in early apoptosis and 53% in late apoptosis stage. The obtained results suggest that ZnO nanoparticle conjugated dipeptide initiated cytotoxicity through apoptotic death in HepG2 cells. The embryotoxic studies in zebrafish embryos revealed the LC50 197.0 μg/mL. These findings suggest that conjugated dipeptide affected the development of zebrafish embryos only at relatively higher concentrations.

Conclusion:

The experimental results demonstrate that ZnO nanoparticle conjugated dipeptide has the potential to improve anticancer efficacy against liver cancer cells by inducing apoptosis in cancer cells without any effect on normal liver cells.

Book Review: Layered Materials for Energy Storage and Conversion

Background:

A Book Review on Layered Materials for Energy Storage and Conversion Edited by Dongsheng Geng, Yuan Cheng and Gang Zhang, The Royal Society of Chemistry, 2019, 315 Pages, Print ISBN 978-1-78801-426-7, Print ISSN 2046-0066, DOI: 10.1039/9781788016193- FP001.

:

In the earlier decade, the extensive research hot-spot in two-dimensional (2D) layered materials, especially graphene, metal-organic frameworks (MOFs) and transition metal dichalcogenides (TMDCs) benefited from their exceptional chemical, physical, optical, mechanical and electronic properties. This book provides an up-to-date comprehensive overview of synthesis approaches and functionalization routes of graphene and TMDCs and functional properties of intercalated layered materials and its energy applications.

Methods:

The chemistry of layered two-dimensional materials towards its allied applications in electrocatalysis, lithium-ion batteries, sodium-ion batteries, thermoelectric materials, watersplitting and performance of photovoltaic devices are the core issues of energy storage and conversion and they are well addressed in this book.

Results:

This book consists of nine chapters. Altogether they discuss layered materials, energy storage, substitute energy storage and conversion specifically as it is not possible to discuss each and everything in detail. The chapters are written well by reputed experts around the globe. That makes this book an outstandingly important and reliable source of information. It is valuable for a book to provide updated information, review the work done to date, do proper analysis, compare the pros and cons of comparable existing technologies and guide the readers to the research gaps and places where improvement is required.

Conclusion:

This book is an essential reference guide for students, researchers, engineers and professionals in the advanced materials community and energy-related sectors such as photovoltaics, water-splitting, supercapacitor, and batteries, etc.

Book Review on “Nanotechnology: Food and Environmental Paradigm”

Background::

A Book Review on Nanotechnology: Food and environmental paradigm, is edited by Ram Prasad, Vivek Kumar and Manoj Kumar, Springer Nature Singapore, 2017, 340 Pages, ISBN 978-981-10-4677-3, DOI 10.1007/978-981-10-4678-0.

:

This book aims to study the effects of nanomaterials on the environment and food and emphasizes the advantages gained through the application of nanotechnology in the broader area of food and environment.

Methods:

Food web is the core of ecological balance for a sustainable environment. The presence of undesired nanomaterials in the food chain or web causes unwanted toxicity to the plants and animals of the food chain. In majority cases, the presence of nanomaterials in food web causes toxicity, impairment of organs and/ or heavy loss to one or more population. Thus, it is highly required to limit the release of nanomaterials in the environment. It is also necessary to set the norms for the production, use and discard of nanomaterials.

Results:

This book consists of 16 chapters, which all together address a large dimension on the positive and negative effects of nanomaterials and the application of nanotechnology in various fields of food, agriculture and pharmaceutical industry. It is also important to evaluate the cost before implementing any new technology. It is not necessary that good research which performed well in the laboratory must also do well on the industrial scale. A major barrier which can be encountered is actually the cost, which must be less to be implemented.

Conclusion:

Application of desired nanomaterials is advantageous for many industries and quality life. Nano-fertilizers and nanopesticides enhance crop production. Nanotechnology plays a significant role in the food industry, from production, processing to packaging. Diagnostics is a field where nanotechnology is applied too much. New diagnostic methods using nanosensors, nanochips and nanocatalysts are evolving day by day.