Graphene quantum dots prepared from dried lemon leaves and microcrystalline mosaic structure

Advances in spin properties of plant leaf-derived graphene quantum dots from materials to applications

Over the past decade, graphene quantum dots (GQDs) have gained an inexhaustible deal of attention due to their unique zero-dimensional (0D) and quantum confinement properties, which boosted their wide research implication and reliable applications. As one of the promising 0D member and rising star of the carbon family, plant leaf-derived GQDs have attracted significant attention from scholars working in different research fields. Owing to its novel photophysical properties including high photo-stability, plant leaf-derived GQDs have been increasingly utilized in the fabrication of optoelectronic devices. Their superior biocompatibility finds their use in biotechnology applications, while their fascinating spin and magnetic properties have maximized their utilization in spin-manipulation devices. In order to promote the applications of plant leaf-derived GQDs in different fields, several studies over the past decade have successfully utilized plant leaf as sustainable precursor and synthesized GQDs with various sizes using different chemical and physical methods. In this review, we summarize the Neem and Fenugreek leaves based methods of synthesis of plant leaf-derived GQDs, discussing their surface characteristics and photophysical properties. We highlight the size and wavelength dependent photoluminescence properties of plant leaf-derived GQDs towards their applications in optoelectronic devices such as white light-emitting diodes and photodetectors, as well as biotechnology applications such asin vivoimaging of apoptotic cells and spin related devices as magnetic storage medium. Finally, we particularly discuss possible ways of fine tuning the spin properties of plant leaf-derived GQD clusters by incorporation with superconducting quantum interference device, followed by utilization of atomic force microscopy and magnetic force microscopy measurements for the construction of future spin-based magnetic storage media and spin manipulation quantum devices so as to provide an outlook on the future spin applications of plant leaf-derived GQDs.

POE-Mediated Tunable Quantum Yield of Carbon Dots-Derived From Agapanthus Africanus (L.) Hoffmann Leaves

The green synthesis of carbon dots (CDs) from natural sources is a challenging goal. Herein CDs are produced from Agapanthus africanus (L.) Hoffmann leaves by carbonization at 200/300 °C for 2/3 h. Samples are named CZ-X-Y, where Z, X, and Y represent carbonization, temperature, and time, respectively. CZ-200-3, CZ-300-2, and CZ-300-3 CDs have average sizes of 3.7 ± 0.7, 5.3 ± 1.2, and 5.1 ± 1.6 nm, respectively. Their surface, devoid of chlorophyll, contains ─OH, ─C═O, and ─C(═O)OH groups and sylvite. Isolated CZ-300-3 emits at 400 nm (excited at 260 nm) and exhibits an emission quantum yield (QY) value of 2 ± 1%. Embedding in the d-U(600)/d-(900) di-ureasil matrices resulted in transparent films with emission intensity maxima at 420/450 nm (360 nm), and QY values of 7 ± 1/16 ± 2% (400 nm). The enhancement of the QY value of the bare CDs agrees with an efficient passivation provided by the hybrid host. The hydrophilic CZ-300-3 CDs also exerted a marked surface modifying role, changing the surface roughness and the wettability of the hybrid films.

Functionalized Graphene Quantum Dots (GQDs) based Label-Free Optical Fluorescence Sensor for CD59 Antigen Detection and Cellular Bioimaging

Cluster of differentiation (CD59), a cell surface glycoprotein, regulates the complement system to prevent immune damage. In cancer, altered CD59 expression allows tumors to evade immune surveillance, promote growth, and resist certain immunotherapies. Targeting CD59 could enhance cancer treatment strategies by boosting the immune response against tumors. Herein, we present a one-step synthesis of Polyethyleneimine (PEI) functionalized graphene quantum dots (Lf-GQDs) from weathered lemon leaf extract. The fabricated Lf-GQDs were successfully used for the quantitative detection of the cluster of CD59 antigen that is reported for its expression in different types of cancer. In this work, we utilized orientation-based attachment of CD59 antibody (Anti-CD59). Our findings reveal that, instead of using random serial addition of antigen or antibody, oriented conjugation saves accumulated concentration offering greater sensitivity and selectivity. The Anti-CD59@Lf-GQDs immunosensor was fabricated using the oriented conjugation of antibodies onto the Lf-GQDs surface. Besides, the fabricated immunosensor demonstrated detection of CD59 in the range of 0.01 to 40.0 ng mL-1 with a low detection limit of 5.3 pg mL-1. Besides, the cellular uptake potential of the synthesized Lf-GQDs was also performed in A549 cells using a bioimaging study. The present approach represents the optimal utilization of Anti-CD59 and CD59 antigen. This approach could afford a pathway for constructing oriented conjugation of antibodies on the nanomaterials-based immunosensor for different biomarkers detection.

WITHDRAWN: Prospects of graphene quantum dots preparation using lignocellulosic wastes for application in photofermentative hydrogen production

This paper has been withdrawn.

Recent advancements and prospects in carbon-based nanomaterials derived from biomass for environmental remediation applications

The conversion of waste biomass into a value-added carbonaceous nanomaterial highlights the appealing power of biomass valorization. The advantages of using sustainable and cheap biomass precursors exhibit the tremendous opportunity for boosting energy production and their application in environmental remediation processes. This review emphasis the development and production of carbon-based nanomaterials derived from biomass, which possess favourable characteristics such as biocompatibility and photoluminescence. The advantages and limitations of various nanomaterials synthesised from different precursors were also discussed with insights into their physicochemical properties. The surface morphology of the porous nanomaterials is also explored along with their characteristic properties like regenerative nature, non-toxicity, ecofriendly nature, unique surface area, etc. The incorporation of various functional groups confers superiority of these materials, resulting in unique and advanced functional properties. Further, the use of these biomass derived nanomaterials was also explored in different applications like adsorption, photocatalysis and sensing of hazardous pollutants, etc. The challenges and outcomes obtained from different carbon-based nanomaterials are briefly outlined and discussed in this review.

Sustainable Preparation of Graphene Quantum Dots from Leaves of Date Palm Tree

The date palm (Phoenix dactylifera), a subtropical and tropical tree, included in the family Palmae (Arecaceae) is one of the oldest cultivated plants of mankind. Date palm is a major agricultural product in the semi-arid and arid areas of the world, particularly in Arab countries. These trees generate high quantities of agricultural waste in the form of dry leaves, seeds, etc. In this study, dried date palm leaves were used as green precursors for synthesizing graphene quantum dots (GQDs). This work reported the preparation of GQDs using two different sustainable methods. GQD-1 was developed using a simple, hydrothermal technique at 200 °C for 12 h in water, with no requirement of reducing or passivizing agents or organic solvents. GQD-2 was prepared using a hydrothermal technique at 200 °C for 12 h in water, with the usage of just distilled water and absolute ethanol. The compositional analysis of the leaf extract was performed, along with the morphological, compositional, and optical examination of the sustainably developed GQDs. The characterization results confirmed the successful formation of GQDs, with average sizes ranging from 3.5 to 8 nm. This study helps to obtain GQDs in an economical, eco-friendly, and biocompatible manner and can assist in large-scale production and in recycling date palm tree waste products from Middle East countries into value-added products.

Obtaining the best temperature parameters for co-carbonization of lignite (yatağan)-biomass (peach seed shell) by structural characterization

In this study, Yatağan lignite (YL) and peach kernel shells (PKS) were originally taken separately and in a 1: 1 ratio by weight. Experiments were carried out in a 3-zone heated cylindrical furnace in a steel reactor. Structural characterization of all the solid products obtained was made by FTIR, XRD, and SEM analysis. When the FTIR and XRD spectra of the raw samples are examined, it is seen that they are rich in functional groups. It is seen that the PKS has aliphatic and aromatic structures and cellulosic structure –OH stresses (3500 cm⁻¹). The sharp peak around 2918 cm⁻¹ in Yatağan lignite belongs to the aliphatic C–H stretch. In the XRD spectrum, it is seen that both structures are largely amorphous. The raw PKS contains 3 different amorphous macromolecular structures. Yatagan lignite, on the other hand, contains crystalline peaks of clay and inorganic structures, depending on the ash content, as well as the amorphous structure. As the temperature increases depending on the carbonization temperature, as seen in the FTIR spectrum, the peaks of the functional groups decrease and disappear with the disruption of small macromolecular structures. As a result of the structural adjustment with the temperature increase, M-O-M peaks around 1000 cm⁻¹ remain due to the aromatic C–H stretching and ash content. The paper centers around test assurance of operating temperatures in the consuming layer during co-carbonization. It is obtained that 800 °C is the best temperature condition for the co-carbonization process. It has been concluded that the chars obtained as a result of pyrolysis will be used as a solid fuel in both environmental (the lowest sulfur content) and economic (400 °C) sense. However, the fact that it has a very low sulfur content with the increase in the liquid and gas efficiency obtained at high temperatures again proves the production of an environmentally friendly liquid fuel.