Distribution of different surface modified carbon dots in pumpkin seedlings

Uv-vis spectroscopy for simple chloride content analysis in edible oil using charged amino-functionalized carbon quantum dots fluorophore reagent

The utilization of UV-Vis spectroscopy with amino-functionalized carbon quantum dots (NCQD) as a positive fluorophore reagent for chloride sensing in oil marks a notable advancement in analytical spectroscopy chemistry. This approach streamlines the detection process by eliminating the need for lengthy procedures and pretreatment steps typically associated with chloride detection in edible oil. By incorporating NCQD in chloride detection within the oil matrix, the wavelength analysis transitions from the UV to the visible region. This shift eliminates interference from oil matrix interactions, ensuring more accurate results. Molecular analysis of NCQD reveals significant shifts in its Fourier Transformation Infrared and photoluminescence spectroscopy peaks due to interaction with chloride in edible oil. It has two impressive sensitivity ranges spanning from 0.1-1.0 to 1.0-8.0 ppm, with a value of -0.4656 au. ppm-1 (R2 = 0.998) and -0.0361 au. ppm-1 (R2 = 0.931), respectively, the technique meets regulatory standards while achieving a low limit of detection (LOD) of 0.1 ppm. This places it on par with conventional methods and commercial sensors. The NCQD-UV-Vis spectroscopy method not only enhances the efficiency and accuracy of chloride detection but also holds promise for various industrial applications requiring simple and precise monitoring of chloride levels in oil samples.

Fluorescent carbon dot embedded polystyrene: an alternative for micro/nanoplastic translocation study in leguminous plants

Micro/nanoplastics are widespread in terrestrial ecosystem. Even though many studies have been reported on the effects of these in marine environment, studies concerning their accumulation and impact on terrestrial ecosystem have been scanty. The current study was designed to determine how terrestrial plants, especially legumes, interact with micro/nanoplastics to gain insights into their uptake and translocation. The paper describes the synthesis of fluorescent carbon dot embedded polystyrene (CDPS) followed by its characterization. Translocation studies at different concentrations from 2 to 100% (v/v) for tracking the movement and accumulation of microplastics in Vigna radiata and Vigna angularis were performed. The optical properties of the synthesized CDPS were investigated, and their translocation within the plants was visualized using fluorescence microscopy. These findings were further validated by scanning electron microscopy (SEM) imaging of the plant sections. The results showed that concentrations higher than 6% (v/v) displayed noticeable fluorescence in the vascular region and on the cell walls, while concentrations below this threshold did not. The study highlights the potential of utilizing fluorescent CDPS as markers for investigating the ecological consequences and biological absorption of microplastics in agricultural systems. This method offers a unique technique for monitoring and analyzing the routes of microplastic accumulation in edible plants, with significant implications for both food safety and environmental health.

Carbon Nanodot-Microbe-Plant Nexus in Agroecosystem and Antimicrobial Applications

The intensive applications of nanomaterials in the agroecosystem led to the creation of several environmental problems. More efforts are needed to discover new insights in the nanomaterial-microbe-plant nexus. This relationship has several dimensions, which may include the transport of nanomaterials to different plant organs, the nanotoxicity to soil microbes and plants, and different possible regulations. This review focuses on the challenges and prospects of the nanomaterial-microbe-plant nexus under agroecosystem conditions. The previous nano-forms were selected in this study because of the rare, published articles on such nanomaterials. Under the study's nexus, more insights on the carbon nanodot-microbe-plant nexus were discussed along with the role of the new frontier in nano-tellurium-microbe nexus. Transport of nanomaterials to different plant organs under possible applications, and translocation of these nanoparticles besides their expected nanotoxicity to soil microbes will be also reported in the current study. Nanotoxicity to soil microbes and plants was investigated by taking account of morpho-physiological, molecular, and biochemical concerns. This study highlights the regulations of nanotoxicity with a focus on risk and challenges at the ecological level and their risks to human health, along with the scientific and organizational levels. This study opens many windows in such studies nexus which are needed in the near future.

An assessment of nanotechnology-based interventions for cleaning up toxic heavy metal/metalloid-contaminated agroecosystems: Potentials and issues

Heavy metals (HMs) are among the most dangerous environmental variables for a variety of life forms, including crops. Accumulation of HMs in consumables and their subsequent transmission to the food web are serious concerns for scientific communities and policy makers. The function of essential plant cellular macromolecules is substantially hampered by HMs, which eventually have a detrimental effect on agricultural yield. Among these HMs, three were considered, i.e., arsenic, cadmium, and chromium, in this review, from agro-ecosystem perspective. Compared with conventional plant growth regulators, the use of nanoparticles (NPs) is a relatively recent, successful, and promising method among the many methods employed to address or alleviate the toxicity of HMs. The ability of NPs to reduce HM mobility in soil, reduce HM availability, enhance the ability of the apoplastic barrier to prevent HM translocation inside the plant, strengthen the plant's antioxidant system by significantly enhancing the activities of many enzymatic and nonenzymatic antioxidants, and increase the generation of specialized metabolites together support the effectiveness of NPs as stress relievers. In this review article, to assess the efficacy of various NP types in ameliorating HM toxicity in plants, we adopted a 'fusion approach', in which a machine learning-based analysis was used to systematically highlight current research trends based on which an extensive literature survey is planned. A holistic assessment of HMs and NMs was subsequently carried out to highlight the future course of action(s).

Dynamics of organic acid exudation and rhizobacteria in maize rhizosphere respond to N-CDs

To sustainably feed the growing global population, it is essential to increase crop yields on limited land while reducing the use of fertilizers and agrochemicals. The rhizosphere regulation shows significant potential to address this challenge. Here, foliar applied doping of nitrogen in carbon dots (N-CDs) entered maize leaves, and were transported to the stems and roots. The internalized N-CDs significantly increased the biomass (26.4-93.8%) and photosynthesis (17.0-20.3 %) of maize seedling during the three-week application of N-CDs, providing the substrate for tricarboxylic acid cycle (TCA) in shoots and roots. Correspondingly, more organic acids involved in TCA cycle, such as citric acid (14.0-fold), succinic acid (4.4-fold) and malic acid (3.4-fold), were synthesized and then secreted into rhizosphere after exposed to N-CDs for one day. As the exposure time increased, greater secretion of above organic acids by the roots was induced. However, no significant change was observed in the relative abundance of rhizobacteria after foliar application with N-CDs for one day. After one week, the relative abundances of Azotobacter, Bacillus, Lysobacter, Mucilaginibacter, and Sphingomonas increased by 0.8-3.8 folds. The relative abundance of more beneficial rhizobacteria (Sphingomonas, Lysobacter, Rhizobium, Azotobacter, Pseudomonas, Mucilaginibacter and Bacillus) enriched by 0.3-6.0 folds after two weeks, and Sphingomonas, Flavisolibacter and Bacillus improved by 0.6-3.2 folds after three weeks. These dynamic changes suggested that N-CDs initiate the synthesis and secretion of organic acids and then recruited beneficial rhizobacteria. The hierarchical partitioning analysis further indicated that N-CDs-induced secretion of organic acids from the roots was the main drivers of rhizobacteria community dynamics. The differential microbes altered by N-CDs were mainly involved in nitrogen (N) and phosphorus (P) cycles, which are beneficial for N and P uptake, and maize growth. These results provide insights into understanding the rhizosphere regulation of nanomaterials to improve plant productivity and nutrient-use efficiency.

Nanoplatforms for the Delivery of Nucleic Acids into Plant Cells

Nanocarriers are widely used for efficient delivery of different cargo into mammalian cells; however, delivery into plant cells remains a challenging issue due to physical and mechanical barriers such as the cuticle and cell wall. Here, we discuss recent progress on biodegradable and biosafe nanomaterials that were demonstrated to be applicable to the delivery of nucleic acids into plant cells. This review covers studies the object of which is the plant cell and the cargo for the nanocarrier is either DNA or RNA. The following nanoplatforms that could be potentially used for nucleic acid foliar delivery via spraying are discussed: mesoporous silica nanoparticles, layered double hydroxides (nanoclay), carbon-based materials (carbon dots and single-walled nanotubes), chitosan and, finally, cell-penetrating peptides (CPPs). Hybrid nanomaterials, for example, chitosan- or CPP-functionalized carbon nanotubes, are taken into account. The selected nanocarriers are analyzed according to the following aspects: biosafety, adjustability for the particular cargo and task (e.g., organelle targeting), penetration efficiency and ability to protect nucleic acid from environmental and cellular factors (pH, UV, nucleases, etc.) and to mediate the gradual and timely release of cargo. In addition, we discuss the method of application, experimental system and approaches that are used to assess the efficiency of the tested formulation in the overviewed studies. This review presents recent progress in developing the most promising nanoparticle-based materials that are applicable to both laboratory experiments and field applications.

A Fluorescent Vector of Carbon Dot to Deliver Rab13 and Rab14 Plasmids for Promoting Neurite Outgrowth

The complex processes of neuron differentiation and neuron repair are critical for treating nervous system injuries and neurodegenerative diseases. Neurite outgrowth plays a crucial role in these processes by enabling the formation of connections between neurons and the generation of neuroplasticity to restore the function of the nervous system. In this study, we fabricated functionalized carbon dots (CDs) with distinctive photoluminescence and low cytotoxicity for use as fluorescence imaging probes and nanocarriers to deliver plasmid DNAs to neurons effectively for inducing neurite outgrowth. CDs were prepared through a reflux process in nitric acid solution, and their surface was then modified using polyethylenimine (PEI) to obtain positively charged CDs for increasing the absorption of plasmid DNAs and the efficiency of cell uptake. Experimental results indicated that the fabricated CDs maintained a low cytotoxicity and exhibited a high neuron uptake of up to 97%. An improvement in the plasmid DNA ingestion of neurons resulted in enhanced expression of Rab13-Q67L and Rab14 proteins, which considerably promoted neurite sprouting and elongation. After the fabricated PEI-modified CDs were used to deliver the Rab13-Q67L and Rab14 plasmids, more than 56% of the neurons had a neurite length that was greater than twice the size of their soma. Thus, DNA delivery through functionalized CDs has a high potential for use in gene therapy for neuronal injuries and diseases.

Recent developments, applications and challenges for carbon quantum dots as a photosynthesis enhancer in agriculture

Since the world's population is expanding, mankind may be faced with a huge dilemma in the future, which is food scarcity. The situation can be mitigated by employing sustainable cutting-edge agricultural methods to maintain the food supply chain. In recent years, carbon quantum dots (CQD), a member of the well-known carbon-based nanomaterials family, have given rise to a new generation of technologies that have the potential to revolutionise horticulture and agriculture research. CQD has drawn much attention from the research community in agriculture owing to their remarkable properties such as good photoluminescence behaviour, high biocompatibility, photo-induced electron transfer, low cost, and low toxicity. These unique properties have led CQD to become a promising material to increase plant growth and yield in the agriculture field. This review paper highlights the recent advances of CQD application in plant growth and photosynthesis rate at different concentrations, with a focus on CQD uptake and translocation, as well as electron transfer mechanism. The toxicity and biocompatibility studies of CQD, as well as industrial scale applications of CQD for agriculture are discussed. Finally, the current challenges of the present and future perspectives in this agriculture research are presented.

The mechanism of coumarin inhibits germination of ryegrass (Lolium perenne) and its application as coumarin-carbon dots nanocomposites

BACKGROUND

As an important plant allelochemical, coumarin can effectively inhibit the germination of various seeds. However, little is known about the inhibition mechanism of coumarin on weed seed germination. Moreover, the herbicidal activity of coumarin is needed to be improved as a natural pesticide.

RESULTS

Coumarin had the highest inhibition effect on the ryegrass (Lolium perenne) seed, where coumarin disturbed the hormone pathway by decreasing the content of gibberellic acid 3, resulting in the reduction of amylase activity and consumption of starch during the germination process of ryegrass seed. Moreover, coumarin induced decreased activity of catalase and subsequently led to the accumulation of hydrogen peroxide and malondialdehyde, causing oxidative stress during the germination process of ryegrass seed. Furthermore, to enhance the herbicidal activity of coumarin, carbon dots (CDs) modified with polyetherimide were prepared, characterized, and then combined with coumarin to form coumarin-carbon dots (Cm-CDs) nanocomposites. Compared with coumarin, Cm-CDs nanocomposites significantly increased the herbicidal activity of coumarin on ryegrass, which implies that Cm-CDs nanocomposites could be used as a potential formulation to improve the herbicidal activity of coumarin.

CONCLUSION

This study not only reveals the mechanism of coumarin on ryegrass germination, but also develop Cm-CDs nanocomposites to enhance the herbicidal activity of coumarin. Our findings will stimulate the application of Cm-CDs nanomaterials as an effective and environmentally friendly formulation in agriculture. © 2023 Society of Chemical Industry.

Engineered nanoparticles in plant growth: Phytotoxicity concerns and the strategies for their attenuation

In the agricultural sector, the use of engineered nanoparticles (ENPs) has been acclaimed as the next big thing for sustaining and increasing crop productivity. A vast amount of literature is available regarding the growth-promoting attributes of different ENPs. In this context, it has been emphasized that the ENPs can bolster vegetative growth, leaf development, and seed setting and also help in mitigating the effects of abiotic and biotic stresses. At the same time, there have been a lot of speculations and concerns regarding the phytotoxicity of ENPs off-late. In this connection, many research articles have presented the negative effects of ENPs on plant systems. These studies have highlighted that almost all the ENPs impart a certain degree of phytotoxicity in terms of reduction in growth, biomass, impairment of photosynthesis, oxidative status of plant cells, etc. Mostly, the ENPs based on metal or metal oxides (Cd, Cr, Pb, Ag, Ce, etc.) and nonmetals (C) that are introduced into the environment are known to incite inhibitory effects. However, the phytotoxicity of ENPs are known to be determined mostly by the chemical nature of the element, size, surface charge, coating molecules, and abiotic factors like pH and light. This review article, therefore, elucidates the phytotoxic properties of different ENPs and the plant responses induced at the molecular level subjected to nanoparticle exposure. Moreover, the article highlights the probable strategies that may be adopted for the suppression of the phytotoxicity of ENPs to ensure the safe and sustainable application of ENPs in crop fields.

Recent Progress on Nanocarriers for Topical-Mediated RNAi Strategies for Crop Protection—A Review

To fulfil the growing needs of the global population, sustainability in food production must be ensured. Insect pests and pathogens are primarily responsible for one-third of food losses and harmful synthetic pesticides have been applied to protect crops from these pests and other pathogens such as viruses and fungi. An alternative pathogen control mechanism that is more “friendly” to the environment can be developed by externally applying double-stranded RNAs (dsRNAs) to suppress gene expression. However, the use of dsRNA sprays in open fields is complicated with respect to variable efficiencies in the dsRNA delivery, and the stability of the dsRNA on and in the plants, and because the mechanisms of gene silencing may differ between plants and between different pathogen targets. Thus, nanocarrier delivery systems have been especially used with the goal of improving the efficacy of dsRNAs. Here, we highlight recent developments in nanoparticle-mediated nanocarriers to deliver dsRNA, including layered double hydroxide, carbon dots, carbon nanotubes, gold nanoparticles, chitosan nanoparticles, silica nanoparticles, liposomes, and cell-penetrating peptides, by review of the literature and patent landscape. The effects of nanoparticle size and surface modification on the dsRNA uptake efficiency in plants are also discussed. Finally, we emphasize the overall limitation of dsRNA sprays, the risks associated, and the potential safety concerns for spraying dsRNAs on crops.

Biogenic Synthesis of Fluorescent Carbon Dots (CDs) and Their Application in Bioimaging of Agricultural Crops

Fluorescent nanoparticles have a transformative potential for advanced sensors and devices for point-of-need diagnostics and bioimaging, bypassing the technical burden of meeting the assay performance requirements. Carbon dots (CDs) are rapidly emerging carbon-based nanomaterials. Regardless of their fate, they will find increasing applications. In this study, a simple approach for synthesizing CDs from fruit peels was developed. The CDs were fabricated from Annona squamosa (L.) peels using a carbonization technique through microwave-assisted hydrothermal digestion at temperatures around 200 °C. Synthesized CDs were detected using a UV transilluminator for the preliminary confirmation of the presence of fluorescence. UV-Vis spectrophotometry (absorbance at 505 nm) analysis, zeta potential measurement (-20.8 mV), nanoparticles tracking analysis (NTA) (average size: 15.4 nm and mode size: 9.26 nm), photoluminescence, and Fourier transform infrared (FT-IR) analysis were used to identify the capping functional groups on the CDs. The total quantum yield exhibited was 8.93%, and the field emission scanning electron microscopy (FESEM) showed the size range up to 40 nm. The germinating mung bean (Vigna radiata (L.)) seeds were incubated with biogenically synthesized CDs to check the absorption of CDs by them. The fluorescence was observed under a UV-transilluminator in the growing parts of seeds, indicating the absorption of CDs during the germination, development, and growth. These fluorescent CDs could be used as a bioimaging agent. This novel method of synthesizing CDs was found to be eco-friendly, rapid, and cost-effective.

Sustainable agronomic response of carbon quantum dots on Allium sativum: Translocation, physiological responses and alternations in chromosomal aberrations

The revolutionary growth in the usage of carbon quantum dots (CQDs) in different areas have ultimately directed their discharge in the environment and further augmented the exposure of agricultural crops to these released particles. Therefore, the aim of current study is to evaluate the uptake, translocation and phytotoxicity of blue emissive CQDs on Allium sativum plant. The genotoxicity and cytotoxicity assessment of CQDs towards Allium sativum roots was estimated as function of three different concentrations. Considering the role of CQDs in promoting seed germination at 50 ppm concentration, a greenhouse experiment was performed to evaluate their effect on plant growth. Systematic investigations have shown the translocation of CQDs and their physiological response in terms of increased shoot length wherein P-CQDs exhibited more accumulation into Allium sativum parts. Our investigations unfold the opportunity to utilize Aegle marmelos fruit derived CQDs as a growth regulator in variety of other food plants.

Chlorophyll Detection by Localized Surface Plasmon Resonance Using Functionalized Carbon Quantum Dots Triangle Ag Nanoparticles

An optical sensor-based localized surface plasmon resonance (LSPR) sensor was demonstrated for sensitive and selective chlorophyll detection through the integration of amino-functionalized carbon quantum dots (NCQD) and triangle silver nanoparticles (AgNPs). The additions of amino groups to the CQD enhance the detection of chlorophyll through electrostatic interactions. AgNPs-NCQD composite was fabricated on the surface of the silanized glass slide using the self-assembly technique. The experimental results showed that the AgNPs-NCQD film-based LSPR sensor detects better than AgNPs and AgNPs-CQD films with a good correlation coefficient (R² = 0.9835). AgNPs-NCQD showed a high sensitivity response of 2.23 nm ppm^-1. The detection and quantification limits of AgNPs-NCQD are 1.03 ppm and 3.40 ppm, respectively, in the range of 0.05 to 6 ppm. Throughout this study, no significant interference was observed among the other ionic species (NO₂^-, PO₄^-, NH₄⁺, and Fe³⁺). This study demonstrates the applicability of the proposed sensor (AgNPs-NCQD) as a sensing material for chlorophyll detection in oceans.

Carbon Dots Boost dsRNA Delivery in Plants and Increase Local and Systemic siRNA Production

In this work, we obtained carbon dots from glucose or saccharose as the nucleation source and passivated them with branched polyethylenimines for developing dsRNA nanocomposites. The CDs were fully characterized using hydrodynamic analyses, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The ζ potential determined that the CDs had positive charges, good electrophoretic mobility and conductivity, and were suitable for obtaining dsRNA nanocomposites. DsRNA naked or coated with the CDs were delivered to leaves of cucumber plants by spraying. Quantitation of the dsRNA that entered the leaves showed that when coated with the CDs, 50-fold more dsRNA was detected than when naked dsRNA. Moreover, specific siRNAs derived from the sprayed dsRNAs were 13 times more abundant when the dsRNA was coated with the CDs. Systemic dsRNAs were determined in distal leaves and showed a dramatic increase in concentration when delivered as a nanocomposite. Similarly, systemic siRNAs were significantly more abundant in distal leaves when spraying with the CD-dsRNA nanocomposite. Furthermore, FITC-labeled dsRNA was shown to accumulate in the apoplast and increase its entry into the plant when coated with CDs. These results indicate that CDs obtained by hydrothermal synthesis are suitable for dsRNA foliar delivery in RNAi plant applications.

Foliar carbon dot amendment modulates carbohydrate metabolism, rhizospheric properties and drought tolerance in maize seedling

Improving maize drought tolerance is of great importance for scaling up production due to food security and population growth. Carbon dots (CDs) were synthesized by hydrothermal method with citric acid and ethylenediamine as carbon sources. Then, CDs (5 ml, 5 mg‧L^-1) were sprayed on 25th day-old maize (Zea mays L., drought-stress, 35% soil moisture) for seven consecutive days (spraying ultra-pure water as control), after which the physiological parameters and rhizospheric properties of maize under drought were evaluated. Foliar sprayed CDs (5 mg‧L^-1) could increase root exudates (e.g., succinic acid (14.5 folds), pyruvic acid (10.0 folds), and betaine (11.8 folds)), and modify microbial community. Particularly, the relative abundance of Pseudomonas, Sphingomonas, Nitrospira, and Conocybe were significantly increased by 344.4%, 233.3%, 126.2%, and 122.6%, respectively. The altered microbial abundance could improve soil available nitrogen and phosphorus by 33.5% and 16.8%, respectively, and increase plant water uptake by 37.2%. The change of exudate synthesis and microbial abundance could be driven by the significantly increased in net photosynthesis rate by 122.9%, and carbohydrate content by 35.4% in shoots and 113.6% in roots, respectively upon foliar application of CDs. Meanwhile, fresh weight of shoots and roots were increased by 62.1% and 50.6%, and dry weight of shoots and roots were increased by 29.2% and 37.5%, respectively. These results demonstrated that foliar application of CDs could improve the rhizosphere environment to enhance maize drought tolerance and even growth. Therefore, foliar application of CDs would be a promising strategy for sustainable nano-agriculture in response to drought stress.

Localized Surface Plasmon Resonance Decorated with Carbon Quantum Dots and Triangular Ag Nanoparticles for Chlorophyll Detection

This paper demonstrates carbon quantum dots (CQDs) with triangular silver nanoparticles (AgNPs) as the sensing materials of localized surface plasmon resonance (LSPR) sensors for chlorophyll detection. The CQDs and AgNPs were prepared by a one-step hydrothermal process and a direct chemical reduction process, respectively. FTIR analysis shows that a CQD consists of NH₂, OH, and COOH functional groups. The appearance of C=O and NH₂ at 399.5 eV and 529.6 eV in XPS analysis indicates that functional groups are available for adsorption sites for chlorophyll interaction. A AgNP-CQD composite was coated on the glass slide surface using (3-aminopropyl) triethoxysilane (APTES) as a coupling agent and acted as the active sensing layer for chlorophyll detection. In LSPR sensing, the linear response detection for AgNP-CQD demonstrates R² = 0.9581 and a sensitivity of 0.80 nm ppm^-1, with a detection limit of 4.71 ppm ranging from 0.2 to 10.0 ppm. Meanwhile, a AgNP shows a linear response of R² = 0.1541 and a sensitivity of 0.25 nm ppm^-1, with the detection limit of 52.76 ppm upon exposure to chlorophyll. Based on these results, the AgNP-CQD composite shows a better linearity response and a higher sensitivity than bare AgNPs when exposed to chlorophyll, highlighting the potential of AgNP-CQD as a sensing material in this study.

Green synthesis of white light emitting carbon quantum dots: Fabrication of white fluorescent film and optical sensor applications

In this work, we have reported on the facile synthesis of white light-emitting carbon quantum dots (CQD) from corncob by hydrothermal method. This CQD has a broad emission from 380 nm to 650 nm with high photoluminescence intensity even after three months of shelf-life and stable at variable pH conditions. The presence of Si and N impurities in the biomass gives a greater advantage in producing white light emission with high quantum yield (54%) and enhanced lifetime at ambient conditions. The CQD is highly sensitive towards DNA, paracetamol, Pb²⁺, Cu²⁺, Fe³⁺, and Cr³⁺ fluorescence sensing and signifies its application as a multi-modal fluorescence sensor. The results of optical sensitivity calculated from the linear range of 1-10 ng/mL, 0.10-0.30 mg/mL, 2.5446 ng/mL, 0.0694 mg/mL, 0.3103-1.5515 μM/mL, 0.4299-4.7293 μM/mL, 1.3010 μM/mL and 0.05-2.5 μM/mL. The limit of detection is 2.5446 ng/mL, 0.0694 mg/mL, 0.8641 μM/mL, 1.2454 μM/mL, 1.3010 μM/m, 0.8550 μM/mL and 2.8562 μM/mL, respectively. And also, the relative standard deviation values of 2.30%, 4.46%, 1.79%, 1.84%, 0.26%, 1.23% and 0.35% are evidences its possibility of development towards potential optical sensor applications. Flexible white light-emitting sheets were fabricated from the CQD, illuminates uniform brightness, and has good color reproducibility and higher stability under various UV light excitation.

Microwave-assisted green synthesis of fluorescent carbon quantum dots from Mexican Mint extract for Fe3+ detection and bio-imaging applications

Biomass-derived carbon quantum dots have drawn special interest owing to their admirable photostability, biocompatibility, fluorescence, high solubility, sensitivity and environmentally friendly properties. In the present work, the Carbon Quantum Dots (CQDs) was synthesized from the Plectranthus amboinicus (Mexican Mint) leaves via the microwave-assisted reflux method. The strong absorption peaks observed from UV-vis spectra at 291 and 330 nm corresponds to the π-π* and n-π* transitions, respectively, reveal the formation of CQDs. The synthesized CQDs showed bright blue fluorescence under UV irradiation with a fluorescence quantum yield of 17% and a maximum emission of 436 nm in the blue region at an excitation wavelength of 340 nm. The HRTEM analysis elucidates that the synthesized CQDs were crystalline and spherical in shape with a particle size of 2.43 ± 0.02 nm. The FT-IR spectroscopy confirms the presence of the different functional groups such as -OH, -CH, CO and C-O. The chemical composition of CQD was revealed through XPS analysis. The synthesized CQDs were used as a fluorescent probe to detect different metal ions, where high selectivity was obtained for Fe³⁺ ions through quenching phenomenon. The emission intensity of CQD showed a good linear relationship with R² = 0.9111 with the concentration of Fe³⁺ ions in the range of 0-15 μM. The fluorescence emission of CQD was turned OFF upon the binding of Fe³⁺ ions and turned - ON with the addition of ascorbic acid. With this fluorescent turn ON-OFF behaviour of CQD, the NOT and IMPLICATION logic gates were constructed and studied for different input conditions. The biocompatibility of CQD was tested via MTT assay using MCF7 breast cancer cell line, which revealed that CQD synthesized from the Mexican Mint leaves possess less cytotoxicity. Further, the prepared CQD was applied effectively as fluorescent probes in a cell imaging application.

Sodium selenite-carbon dots nanocomposites enhance acaricidal activity of fenpropathrin: Mechanism and application

As an essential trace element, selenium can be used to protect crops from pests, while, in nature, most crops cannot accumulate enough selenium from the soil to reach the effective dose for pest control. In this study, carbon dots modified with arginine in nano-scale was prepared and characterized, then, it was combined with sodium selenite to form selenium-carbon dots (Se-CDs). Function evaluation of Se-CDs showed that it could increase the absorption of selenium in plant leaves, promote the control efficiency of fenpropathrin, and protect plant from damage caused by Tetranychus cinnabarinus. In addition, we found that expressions of P450 genes and activity of P450 enzyme both decreased in selenium treated mites. In vivo, the acaricidal activity of fenpropathrin increased significantly when one of the P450 genes, CYP389B1, was silenced, and the recombinant protein of CYP389B1 could metabolize fenpropathrin in vitro. The results suggested that inhibiting the expression of P450 gene and repressing the detoxification of T. cinnabarinus was the molecular mechanism that how selenium promoted the acaricidal activity of fenpropathrin. The application of Se-CDs in the field will decrease the use of chemicals acaricides, reduce chemical residues, and ensure the safety of agricultural products.

Fluorescent nanoparticles as tools in ecology and physiology

Fluorescent nanoparticles (FNPs) have been widely used in chemistry and medicine for decades, but their employment in biology is relatively recent. Past reviews on FNPs have focused on chemical, physical or medical uses, making the extrapolation to biological applications difficult. In biology, FNPs have largely been used for biosensing and molecular tracking. However, concerns over toxicity in early types of FNPs, such as cadmium-containing quantum dots (QDs), may have prevented wide adoption. Recent developments, especially in non-Cd-containing FNPs, have alleviated toxicity problems, facilitating the use of FNPs for addressing ecological, physiological and molecule-level processes in biological research. Standardised protocols from synthesis to application and interdisciplinary approaches are critical for establishing FNPs in the biologists' tool kit. Here, we present an introduction to FNPs, summarise their use in biological applications, and discuss technical issues such as data reliability and biocompatibility. We assess whether biological research can benefit from FNPs and suggest ways in which FNPs can be applied to answer questions in biology. We conclude that FNPs have a great potential for studying various biological processes, especially tracking, sensing and imaging in physiology and ecology.

Carbon dots inhibit root growth by disrupting auxin biosynthesis and transport in Arabidopsis

Carbon dots (CDs) possess considerable potentials in fields like biomarker and cell imaging due to its good fluorescence properties. Nevertheless, the molecular mechanism concerning influences of CDs on plant growth still remains unknown. In this study, the subcellular localization of CDs in Arabidopsis and the molecular mechanism of CDs toxicity to plants were investigated. Results demonstrate that CDs tend to accumulate in meristematic nucleus of root tips. CDs can inhibit growth of meristem zone of primary root (PR) of Arabidopsis seedlings significantly. The transcription level of auxin biosynthesis related genes decreases and the abundance of auxin efflux carriers PIN1 and PIN2 declines after 40 mg/L CDs treatment, thus lowering the auxin level in root tips. Moreover, CDs weaken activity of cell division in meristem zone by disturbing expressions of DNA damage repair genes and cell cycle regulation genes, thus enabling to inhibit growth of the meristem zone. To sum up, CDs inhibit growth of Arabidopsis seedlings through above pathways. These results provide useful information to elaborate potential toxicity mechanism of CDs on terrestrial plants.

Impacts of surface chemistry of functional carbon nanodots on the plant growth

Functional carbon nanodots (FCNs) with multiple chemical groups have great impact on the growth regulation of plants. To understand the role of the chemical groups, FCNs were reduced from the raw material by pyrolysis method and hydrolysis method. The chemical structure of these materials were characterized by using TGA, TEM, FT-IR, XPS, Raman and elementary analysis. The raw and reduced FCNs were used as plants growth regulators in culture medium of Arabidopsis thaliana. Our results indicate there is a strong correlation between the physiological responses of plants and the surface chemistries (especially carboxyl group and ester group) of the nanomaterials. The quantum-sized FCNs with multiple carboxyl groups and ester groups show better aqueous dispersity and can induce various positive physiological responses in Arabidopsis thaliana seedlings compared with the FCNs decorated without carboxyl and ester as well as aggregated FCNs. The raw FCNs present higher promotion capacity in plants biomass and roots length, and the quantum-sized FCNs are easier to be absorbed by plants and generate more positive effects on plants.

Dual Effect of Nanomaterials on Germination and Seedling Growth: Stimulation vs. Phytotoxicity

Due to recent active research, a large amount of data has been accumulated regarding the effects of different nanomaterials (mainly metal oxide nanoparticles, carbon nanotubes, chitosan nanoparticles) on different plant species. Most studies have focused on seed germination and early seedling development, presumably due to the simplicity of these experimental systems. Depending mostly on size and concentration, nanomaterials can exert both positive and negative effects on germination and seedling development during normal and stress conditions, thus some research has evaluated the phytotoxic effects of nanomaterials and the physiological and molecular processes behind them, while other works have highlighted the favorable seed priming effects. This review aims to systematize and discuss research data regarding the effect of nanomaterials on germination and seedling growth in order to provide state-of-the-art knowledge about this fast developing research area.

Carbon Dots for Efficient Small Interfering RNA Delivery and Gene Silencing in Plants

The initiation of RNA interference (RNAi) by topically applied small interfering RNA has potential applications for plant functional genomics, crop improvement and crop protection, but the primary obstacle for the development of this technology is the efficient delivery of RNAi effectors into the cell. The plant cell wall is a particularly challenging barrier for the delivery of macromolecules because many of the transfection agents that are commonly used with animal cells produce nanocomplexes that are significantly larger than the size exclusion limit of the cell wall. Here, we illustrate the use of a class of very small nanoparticles, called carbon dots, for delivering small interfering RNA into the model plants Nicotiana benthamiana and tomato (Solanum lycopersicum). Low-pressure spray application of these formulations with a spreading surfactant resulted in strong silencing of GFP transgenes in both species. The delivery efficacy of carbon dot formulations was also demonstrated by the silencing of endogenous genes that encode two subunits of magnesium chelatase, an enzyme necessary for chlorophyll synthesis. The strong visible phenotypes observed with the carbon dot-facilitated delivery were validated by measuring significant reductions in the target gene transcript and/or protein levels. Methods for the delivery of RNAi effectors into plants, such as the carbon dot formulations described here, could become valuable tools for gene silencing in plants with practical applications in plant functional genomics and agriculture.

Nanoparticle Charge and Size Control Foliar Delivery Efficiency to Plant Cells and Organelles

Fundamental and quantitative understanding of the interactions between nanoparticles and plant leaves is crucial for advancing the field of nanoenabled agriculture. Herein, we systematically investigated and modeled how ζ potential (-52.3 mV to +36.6 mV) and hydrodynamic size (1.7-18 nm) of hydrophilic nanoparticles influence delivery efficiency and pathways to specific leaf cells and organelles. We studied interactions of nanoparticles of agricultural interest including carbon dots (CDs, 0.5 and 5 mg/mL), cerium oxide (CeO₂, 0.5 mg/mL), and silica (SiO₂, 0.5 mg/mL) nanoparticles with leaves of two major crop species having contrasting leaf anatomies: cotton (dicotyledon) and maize (monocotyledon). Biocompatible CDs allowed real-time tracking of nanoparticle translocation and distribution in planta by confocal fluorescence microscopy at high spatial (∼200 nm) and temporal (2-5 min) resolution. Nanoparticle formulations with surfactants (Silwet L-77) that reduced surface tension to 22 mN/m were found to be crucial for enabling rapid uptake (<10 min) of nanoparticles through the leaf stomata and cuticle pathways. Nanoparticle-leaf interaction (NLI) empirical models based on hydrodynamic size and ζ potential indicate that hydrophilic nanoparticles with <20 and 11 nm for cotton and maize, respectively, and positive charge (>15 mV), exhibit the highest foliar delivery efficiencies into guard cells (100%), extracellular space (90.3%), and chloroplasts (55.8%). Systematic assessments of nanoparticle-plant interactions would lead to the development of NLI models that predict the translocation and distribution of nanomaterials in plants based on their chemical and physical properties.

Influence of Carbon Quantum Dots on the Biome

The latest class of engineered nanomaterials, viz., carbon quantum dots (CQDs), has attracted attention because they are synthesized through green chemical procedures and from organic waste matter. The synthesis of these nano-sized particles synthesized from biomass such as fruit peel and other organic matter results in mixtures of CQD species that differ in chemical identity, activity and photo-physical properties. Generally used collectively as chemically heterogeneous ensemble, they have already had an impact on multiple sectors of our environment by use as wastewater sensors, switches, model agro-fertilizers, and in biomedicine. The transitioning of their applications to crops is an important crossover point that calls for an accurate and detailed assessment of their genomic, proteomic, and metabolomics impact on agriculturally important crops and produce. We review the current status of CQDs vis-à-vis their impact on the biosphere via recent model studies and comment on the knowledge gaps that need to be bridged to ensure their safe use in agronomy. A detailed knowledge of their impact on aquatic systems and the food-chain is critical for human and environmental safety and sustainability.

Applications of carbon nanomaterials in the plant system: A perspective view on the pros and cons

With the remarkable development in the field of nanotechnology, carbon-based nanomaterials (CNMs) have been widely used for numerous applications in different areas of the plant system. The current understanding about the CNMs' accumulation, translocation, plant growth responses, and stress modulations in the plant system is far from complete. There have been relentless efforts by the researchers worldwide in order to acquire newer insights into the plant-CNMs interactions and the consequences. The present review intends to update the reader with the status of the impacts of the different CNMs on plant growth. Research reports from the plant biotechnologists have documented mixed effects (which are dependent on CNMs' concentration) of the CNMs' exposure on plants ranging from enhanced crop yield to acute cytotoxicity. The growth and yield pattern vary from species to species and are dependent on the dosage of the CNMs applied. Studies found an increase in vegetative growth and yield of fruit/seed at lower concentration of CNMs, but a decrease in these observables were also noted when higher concentrations of CNMs were used. In general, at lower concentrations, CNMs were found to be effective in enhancing (water uptake, water transport, seed germination, nitrogenase, photosystem and antioxidant activities), activating (water channels proteins) and promoting (nutrition absorption); all these change when concentrations are raised. All these aspects have been reviewed thoroughly in this article, with a focus on the recent updates on the role of the CNMs in augmenting or retarding plant growth. Sections have been devoted to the various features of the CNMs and their roles in inducing plant growth, phytotoxic responses of the plants and overall crop improvement. Concluding remarks have been added to propose future directions of research on the CNMs-plant interactions and also to sound a warning on the use of CNMs in agriculture.