Multi-walled Carbon nanotube, its role and implications in biological systems are currently under... more Multi-walled Carbon nanotube, its role and implications in biological systems are currently under evaluation and became interesting for many researchers primarily working on the interface of chemistry, physics and biology. However, concerns about the potential toxicity of multi-walled carbon nanotubes have been raised. To carry such affords, herein we investigate the effects of carboxylic acid functionalized water soluble carbon nanotube (wsCNT) on the growth of gram Cicer arietinum plant. The growth of gram plants was observed with and without the presence of wsCNT to demonstrate that carboxylated functionalized multi-walled carbon nanotubes showed better growth and under more wsCNT, the growth was enhanced without showing apparent toxicity. Although this is a preliminary study with a small group of plants, our results encourage further confirmation studies with larger groups of plants.
Plant-nano-carbons interaction have been mostly explored for enhanced germination, cell growth, p... more Plant-nano-carbons interaction have been mostly explored for enhanced germination, cell growth, plant growth, with a limited study on the productivity of seeds under controlled conditions. The present finding reports the sustainable impacts of bio-waste (wood wool) derived nano-carbons as carbon nano-onions (CNOs). On the entire life cycle of gram plants to obtain the "seed to seed" as first generation seeds (FGSs). Water soluble version of CNOs as water soluble carbon nano-onions (wsCNOs) at 0 (control), 10, 20 and 30 µg mL-1 were used for the germination of gram seeds, for the initial 10 days only. Followed by the transferring of 10 days old baby plants into the soil to complete their natural life cycle (~ 4 months). FGSs harvested from the wsCNOs treated plants showed a significant increase in their yield and health with respect to their individual weight, overall dimensions, enhanced protein, stored electrolytes and other micronutrient contents. The protein content increased from 96 µg mL-1 to 170 µg mL-1 and the level of electrolytic conductivity increased from 2.2 mS to 3.4 mS in the FGSs, harvested from the plants treated with 0 µg mL-1 (control) to 30 µg mL-1 of wsCNOs respectively.
Water soluble photoluminescent carbon nano-onions were synthesized from vegetable ghee using trad... more Water soluble photoluminescent carbon nano-onions were synthesized from vegetable ghee using traditional pyrolytic approach for imaging cells and selective-immediate detection of glucose via fluorescent “turn-off”/“turn-on” technique.
ABSTRACT Carbon nano-onions, as a newly-emergent member of the carbon family, have attracted atte... more ABSTRACT Carbon nano-onions, as a newly-emergent member of the carbon family, have attracted attention in its both dry and wet applications. Here we report in vivo effects of water-soluble carbon nano-onions (wsCNOs) introduced in common food web of two model organisms: unicellular Escherichia coli (E. coli) and multicellular Caenorhabditis elegans (C. elegans). At first, CNOs are fed to E. coli and, subsequently, the E. coli are fed to C. elegans. It is found that wsCNOs serve as highly-fluorescent bioimaging agent. The results do not reflect any toxic effect of wsCNOs on the growth of these organisms suggesting new avenues in nanotoxicology research and biomedical application including drug delivery
The image colorfully shows some of the developmental phases of Drosophila melanogaster, which hav... more The image colorfully shows some of the developmental phases of Drosophila melanogaster, which have orally ingested water-soluble carbon nano-onions. The nano-onions are synthesized from wood waste, and they are used to image the entire life cycle of this species-from egg to adulthoodwithout any toxic effect. The fl uorescent organisims excrete the fl uorescing material, and upon removal of the nanoparticles from their diet, they revert to their normal form demonstrating the reversibility of this process. This nontoxic fl uorescent probe would be a viable alternative to barium meal in X-ray imaging.
Fluorescent water soluble carbon nanoparticles (wsCNPs) formed from the carbonization of wood woo... more Fluorescent water soluble carbon nanoparticles (wsCNPs) formed from the carbonization of wood wool followed by oxidative treatment have been used to image the life cycle of the mosquito. At a concentration of wsCNPs around 0.5 mg L À1 , the full life cycle of the mosquito has been successfully imaged. However, at higher concentrations of wsCNPs (3 mg L À1 ), the growth of the mosquito from the larval stage to adulthood is blocked. Larvae ingesting such high concentrations of wsCNPs did not survive and after four weeks perished. The zebra fish can use such infected larvae as food with no ill effect, suggesting a new method to curb mosquito growth in stagnant pools of water treated with wsCNPs without affecting the ecosystem.
The fruit fly, Drosophila melanogaster, is one of the most prominent models to study developmenta... more The fruit fly, Drosophila melanogaster, is one of the most prominent models to study developmental biology. Bioimaging of flies can be difficult-the handling of flies inside an NMR tube has been described as a very tricky job. Another option is optical imaging using fluorescent nanomaterials as contrast agents. These need to be introduced by intravenous/intramuscular injection or by gene translation, both of which can be difficult and time consuming. Sabyasachi Sarkar and colleagues, Indian Institute of Technology, Kanpur, have developed a much simpler way to introduce fluorescent nanomaterials into fruit flies. They use water-soluble carbon nano-onions made from wood waste. The nano-onions are added to the fruit flies' food and ingested orally by the flies. Just 4 ppm of nano-onions allowed the optical fluorescence microscopy imaging of all the stages of the fruit fly life cycle. The fluorescent fruit flies showed no toxic effects-upon withdrawal of the nano-onions from the food, they excreted the fluorescing material and continued to proliferate to the next generation, demonstrating a return to their normal lives. This technique may be used in the easy, noninvasive image-based studies of other animals, and could ultimately be extended to human beings.
Water soluble carbon nanotubes (wsCNTs) with network structure possessing multipodal junctions we... more Water soluble carbon nanotubes (wsCNTs) with network structure possessing multipodal junctions were isolated by the oxidative treatment of carbon soot (generally discarded as waste during fullerene synthesis) using dilute nitric acid as black crystalline solid. wsCNTs having multipodal junctions are highly soluble in water due to the incorporation of adequate amount of hydrophilic carboxylic acid groups. Microscopic investigation shows the presence of extensive networked wsCNTs possessing different types of junctions such as tri (“Y”, “T”), tetrapodal, pentapodal and even “H” type junctions. Furthermore these wsCNTs possessing interesting magnetic properties due to presence of multipodal junctions and defective surfacial structures, usually known as surfacial ‘defects’ on graphitic pool (sp2 hybridized carbon atoms) of nanotubes. Easy solubility along with magnetic properties makes these wsCNTs to be used as a potential probe for their use in biological and spintronic applications respectively.
ABSTRACT We report here the synthesis and structural characterization of a new discrete bis-dithi... more ABSTRACT We report here the synthesis and structural characterization of a new discrete bis-dithiolene complex, [PPh 4 ][Cu(DMED) 2 ] (1; DMED = 1,2-dicarbomethoxy-1,2-dithiolate), involving the reaction between a copper polysulfide precursor with activated acetylene. 1 is stable, showing a sulfur-based radical character, as observed by electronic, EPR and cyclic voltammetric studies. This complex, possessing terminal –COOCH 3 groups, forms nanospheres by hydrogen bonding in a mixture of solvents containing water as one of the components. These nanospheres further aggregate with water soluble (carboxy-lated) carbon nanotubes (wsCNTs). These nano-composites are assisted by hydrogen bonding between the carboxylic acid groups of the wsCNTs and the peripheral –COOCH 3 groups of the coordinated dithiolenes of the nanospheres, which is promoted by water molecules. Interaction between the nano-spheres on wrapping with wsCNTs, in forming the nano-composites, showed a perturbed EPR signal of the sulfur radical originating from the oxidised dithiolate ligand of the discrete complex 1.
Water soluble carbon nanotubes (wsCNTs) show enhancement of the growth rate of common gram (Cicer... more Water soluble carbon nanotubes (wsCNTs) show enhancement of the growth rate of common gram (Cicer arietinum) plants. Treating plants with up to 6.0 μg mL(-1) of wsCNT shows an increased growth rate in every part of the plant including the roots, shoots and also in branching. The noticeable difference between the wsCNT treated and controlled gram is the water uptake; in the former it is dramatically enhanced, suggesting better water absorption and retention related to enhanced growth. This work shows that unlike CNTs, wsCNTs are non-toxic to plant cells that conserve water transport in plants.
Water-soluble carbon nano-onions (wsCNOs) isolated from wood wool-a wood-based pyrolysis waste pr... more Water-soluble carbon nano-onions (wsCNOs) isolated from wood wool-a wood-based pyrolysis waste product of wood, can enhance the overall growth rate of gram (Cicer arietinum) plants. Treatment of plants with upto 30 μg mL(-1) of wsCNOs for an initial 10 day period in laboratory conditions led to an increase in the overall growth of the plant biomass. In order to examine the growth stimulating effects of wsCNOs under natural conditions, 10 day-old plants treated with and without wsCNOs were transplanted into soil of standard carbon and nitrogen composition. We observed an enhanced growth rate of the wsCNOs pre-treated plants in soil, which finally led to an increased productivity of plants in terms of a larger number of grams. On analyzing the carbon, hydrogen, and nitrogen (CHN) content for the shoot and fruit sections of the plants treated with and without wsCNOs, only a minor difference in the composition was noticed. However, a slight increase in the percentage of carbon and hydrogen in shoots reflects the synthesis of more organic biomass in the case of treated plants. This work shows that wsCNOs are non-toxic to plant cells and can act as efficient growth stimulants which can be used as benign growth promoters.
Carbon nanocubes and nanobricks were synthesized by pyrolyzing rice powder at 600 degrees C under... more Carbon nanocubes and nanobricks were synthesized by pyrolyzing rice powder at 600 degrees C under nitrogen atmosphere. Purification with concentrated nitric acid introduced approximately 0.1 mol/g of carboxylic acid groups as found by acid-base titrimetric analysis. XRD pattern showed the 0.15 mol/g basic graphitic structure of these nano carbon materials. Their SEM and TEM images revealed cube or brick shaped nano crystals. These nanocrystals are further characterized by FT-IR, Raman, and EDAX analysis. High density wrapping of carboxylated acid groups introduces surface passivation of these nano carbon cubes and nano carbon bricks exhibiting photoluminescence. Solid state electronic spectrum showed several bands in the ultraviolet and visible region and excitation at 336 and 474 nm generates photoluminescence respectively in the ultraviolet and visible region.
Carboxylic acid functionalized water soluble carbon nanotube (wsCNT) shows no toxic effect agains... more Carboxylic acid functionalized water soluble carbon nanotube (wsCNT) shows no toxic effect against the growth of Escherichia-coli (E.coli), a gram-negative bacteria. Treatment up to 8 g mL −1 of wsCNT did not show any toxic effect on E.coli growth that was followed by using bacterial growth kinetics and Spread Plate Technique (SPT). The number of E-coli colonies counts with and without wsCNT showed nearly no change and the bacterial growth kinetics in both the cases showing no toxic effect of wsCNT on the growth of E.coli.
ABSTRACT A low cost synthesis of multicolor fluorescent carbon dots (C-dots) from edible sugars i... more ABSTRACT A low cost synthesis of multicolor fluorescent carbon dots (C-dots) from edible sugars is described here. Common sugars like dextrose, lactose or maltose in aqueous medium gets dehydrated using phosphorus pentoxide (P2O5). The reaction is facile and completed within few minutes to form insoluble carbon (C-dots) mostly having the graphitic (G-band, Raman) sp2 hybridized carbon atoms (C-atoms). This insoluble carbon on oxidative treatment with nitric acid produced disordered sp3 (D-band retaining G-band, Raman) hybridized C-atoms, originated from the graphitic pool with sp2 hybridized C-atoms. This high density assimilation of self passivated "surfacial defects" become emissive during electronic transitions. Surfacial defects due to high degree of electrophilic carboxylation create the water soluble version of multicolor fluorescent C-dots as "water soluble fluorescent carbon dots" (wsFCDs). wsFCDs being itself self-passivated imposes the tunable multicolor emission throughout the visible spectrum without having any external coating and surface passivation and could be used as multicolor fluorescent probe especially in the emerging field of optical bio-imaging.
Black carbon (BC) (as partly burnt black particulate matter) present indoor are deposited on inte... more Black carbon (BC) (as partly burnt black particulate matter) present indoor are deposited on interior surfaces of the indoors (easily visualize over the blades of electric fan/exhausts and over domestic spider webs) are known to be a potential indoor pollution problem. We detect with the help of indoor spider webs the floating BC contains a significant amount of defective multiwalled carbon nanotubes (MWCNTs) possessing room temperature ferromagnetism. Microscopic studies shows a lot of internal and surfacial defects in these indoor-MWCNTs. Electron paramagnetic resonance (EPR) showed the presence of very stable carbon centred radicals in these indoor-MWCNTs. Room temperature ferromagnetism most importantly originated by the presence of a large amount of unpaired spin frustrated carbon centred radicals (trapped in defects, junctions and fractures) which are inadvertently formed during the pyrolysis of carbonaceous materials through routine domestic activities.
Black carbon (BC) emissions have increased over South Asia and more persistent winter fogs are co... more Black carbon (BC) emissions have increased over South Asia and more persistent winter fogs are common during last decade. However, a physical mechanism connecting these two is still unknown. A significant fraction of BC is known to be in the form of carbon-nanotube (CNT). We have investigated the effects of two different sets of fog condensation nuclei, viz., inorganic salts (sodium chloride and ammonium sulphate) and BC (graphite and CNT) on the dissipation of chamber generated fog under dark and halogen lamp illuminated conditions at a controlled temperature, relative humidity, and fog condensation nuclei distribution. We found that, for inorganic salts, fog dissipates at a faster rate under illumination than in dark conditions showing similar trends for both sodium chloride and ammonium chloride. On the contrary, fog is found to be more persistent, for illuminated conditions, in the case of BC. Moreover, fog persistence is found to be more than twice for CNT compared to graphite in illuminated conditions. CNT is known to be an extremely effective absorber of light which leads to microscopic heating and subsequent evaporation which inhibits droplet growth. Small droplets have large residence time leading to longer fog persistence. This hitherto unknown mechanism may be responsible for persistent fog in India during last decade.
Abstract: The nanocrystal structure of a hetero-polyatomic metal-ligand complex,[PPh 4][Ni II (L ... more Abstract: The nanocrystal structure of a hetero-polyatomic metal-ligand complex,[PPh 4][Ni II (L 2−)(L 1−·)],(1)(L= 1, 2-dicarbomethoxyethylene dithiolate) has been arrived at from its molecular structure obtained by X-ray crystallography. The complex (1) exhibits ...
Multi-walled Carbon nanotube, its role and implications in biological systems are currently under... more Multi-walled Carbon nanotube, its role and implications in biological systems are currently under evaluation and became interesting for many researchers primarily working on the interface of chemistry, physics and biology. However, concerns about the potential toxicity of multi-walled carbon nanotubes have been raised. To carry such affords, herein we investigate the effects of carboxylic acid functionalized water soluble carbon nanotube (wsCNT) on the growth of gram Cicer arietinum plant. The growth of gram plants was observed with and without the presence of wsCNT to demonstrate that carboxylated functionalized multi-walled carbon nanotubes showed better growth and under more wsCNT, the growth was enhanced without showing apparent toxicity. Although this is a preliminary study with a small group of plants, our results encourage further confirmation studies with larger groups of plants.
Plant-nano-carbons interaction have been mostly explored for enhanced germination, cell growth, p... more Plant-nano-carbons interaction have been mostly explored for enhanced germination, cell growth, plant growth, with a limited study on the productivity of seeds under controlled conditions. The present finding reports the sustainable impacts of bio-waste (wood wool) derived nano-carbons as carbon nano-onions (CNOs). On the entire life cycle of gram plants to obtain the "seed to seed" as first generation seeds (FGSs). Water soluble version of CNOs as water soluble carbon nano-onions (wsCNOs) at 0 (control), 10, 20 and 30 µg mL-1 were used for the germination of gram seeds, for the initial 10 days only. Followed by the transferring of 10 days old baby plants into the soil to complete their natural life cycle (~ 4 months). FGSs harvested from the wsCNOs treated plants showed a significant increase in their yield and health with respect to their individual weight, overall dimensions, enhanced protein, stored electrolytes and other micronutrient contents. The protein content increased from 96 µg mL-1 to 170 µg mL-1 and the level of electrolytic conductivity increased from 2.2 mS to 3.4 mS in the FGSs, harvested from the plants treated with 0 µg mL-1 (control) to 30 µg mL-1 of wsCNOs respectively.
Water soluble photoluminescent carbon nano-onions were synthesized from vegetable ghee using trad... more Water soluble photoluminescent carbon nano-onions were synthesized from vegetable ghee using traditional pyrolytic approach for imaging cells and selective-immediate detection of glucose via fluorescent “turn-off”/“turn-on” technique.
ABSTRACT Carbon nano-onions, as a newly-emergent member of the carbon family, have attracted atte... more ABSTRACT Carbon nano-onions, as a newly-emergent member of the carbon family, have attracted attention in its both dry and wet applications. Here we report in vivo effects of water-soluble carbon nano-onions (wsCNOs) introduced in common food web of two model organisms: unicellular Escherichia coli (E. coli) and multicellular Caenorhabditis elegans (C. elegans). At first, CNOs are fed to E. coli and, subsequently, the E. coli are fed to C. elegans. It is found that wsCNOs serve as highly-fluorescent bioimaging agent. The results do not reflect any toxic effect of wsCNOs on the growth of these organisms suggesting new avenues in nanotoxicology research and biomedical application including drug delivery
The image colorfully shows some of the developmental phases of Drosophila melanogaster, which hav... more The image colorfully shows some of the developmental phases of Drosophila melanogaster, which have orally ingested water-soluble carbon nano-onions. The nano-onions are synthesized from wood waste, and they are used to image the entire life cycle of this species-from egg to adulthoodwithout any toxic effect. The fl uorescent organisims excrete the fl uorescing material, and upon removal of the nanoparticles from their diet, they revert to their normal form demonstrating the reversibility of this process. This nontoxic fl uorescent probe would be a viable alternative to barium meal in X-ray imaging.
Fluorescent water soluble carbon nanoparticles (wsCNPs) formed from the carbonization of wood woo... more Fluorescent water soluble carbon nanoparticles (wsCNPs) formed from the carbonization of wood wool followed by oxidative treatment have been used to image the life cycle of the mosquito. At a concentration of wsCNPs around 0.5 mg L À1 , the full life cycle of the mosquito has been successfully imaged. However, at higher concentrations of wsCNPs (3 mg L À1 ), the growth of the mosquito from the larval stage to adulthood is blocked. Larvae ingesting such high concentrations of wsCNPs did not survive and after four weeks perished. The zebra fish can use such infected larvae as food with no ill effect, suggesting a new method to curb mosquito growth in stagnant pools of water treated with wsCNPs without affecting the ecosystem.
The fruit fly, Drosophila melanogaster, is one of the most prominent models to study developmenta... more The fruit fly, Drosophila melanogaster, is one of the most prominent models to study developmental biology. Bioimaging of flies can be difficult-the handling of flies inside an NMR tube has been described as a very tricky job. Another option is optical imaging using fluorescent nanomaterials as contrast agents. These need to be introduced by intravenous/intramuscular injection or by gene translation, both of which can be difficult and time consuming. Sabyasachi Sarkar and colleagues, Indian Institute of Technology, Kanpur, have developed a much simpler way to introduce fluorescent nanomaterials into fruit flies. They use water-soluble carbon nano-onions made from wood waste. The nano-onions are added to the fruit flies' food and ingested orally by the flies. Just 4 ppm of nano-onions allowed the optical fluorescence microscopy imaging of all the stages of the fruit fly life cycle. The fluorescent fruit flies showed no toxic effects-upon withdrawal of the nano-onions from the food, they excreted the fluorescing material and continued to proliferate to the next generation, demonstrating a return to their normal lives. This technique may be used in the easy, noninvasive image-based studies of other animals, and could ultimately be extended to human beings.
Water soluble carbon nanotubes (wsCNTs) with network structure possessing multipodal junctions we... more Water soluble carbon nanotubes (wsCNTs) with network structure possessing multipodal junctions were isolated by the oxidative treatment of carbon soot (generally discarded as waste during fullerene synthesis) using dilute nitric acid as black crystalline solid. wsCNTs having multipodal junctions are highly soluble in water due to the incorporation of adequate amount of hydrophilic carboxylic acid groups. Microscopic investigation shows the presence of extensive networked wsCNTs possessing different types of junctions such as tri (“Y”, “T”), tetrapodal, pentapodal and even “H” type junctions. Furthermore these wsCNTs possessing interesting magnetic properties due to presence of multipodal junctions and defective surfacial structures, usually known as surfacial ‘defects’ on graphitic pool (sp2 hybridized carbon atoms) of nanotubes. Easy solubility along with magnetic properties makes these wsCNTs to be used as a potential probe for their use in biological and spintronic applications respectively.
ABSTRACT We report here the synthesis and structural characterization of a new discrete bis-dithi... more ABSTRACT We report here the synthesis and structural characterization of a new discrete bis-dithiolene complex, [PPh 4 ][Cu(DMED) 2 ] (1; DMED = 1,2-dicarbomethoxy-1,2-dithiolate), involving the reaction between a copper polysulfide precursor with activated acetylene. 1 is stable, showing a sulfur-based radical character, as observed by electronic, EPR and cyclic voltammetric studies. This complex, possessing terminal –COOCH 3 groups, forms nanospheres by hydrogen bonding in a mixture of solvents containing water as one of the components. These nanospheres further aggregate with water soluble (carboxy-lated) carbon nanotubes (wsCNTs). These nano-composites are assisted by hydrogen bonding between the carboxylic acid groups of the wsCNTs and the peripheral –COOCH 3 groups of the coordinated dithiolenes of the nanospheres, which is promoted by water molecules. Interaction between the nano-spheres on wrapping with wsCNTs, in forming the nano-composites, showed a perturbed EPR signal of the sulfur radical originating from the oxidised dithiolate ligand of the discrete complex 1.
Water soluble carbon nanotubes (wsCNTs) show enhancement of the growth rate of common gram (Cicer... more Water soluble carbon nanotubes (wsCNTs) show enhancement of the growth rate of common gram (Cicer arietinum) plants. Treating plants with up to 6.0 μg mL(-1) of wsCNT shows an increased growth rate in every part of the plant including the roots, shoots and also in branching. The noticeable difference between the wsCNT treated and controlled gram is the water uptake; in the former it is dramatically enhanced, suggesting better water absorption and retention related to enhanced growth. This work shows that unlike CNTs, wsCNTs are non-toxic to plant cells that conserve water transport in plants.
Water-soluble carbon nano-onions (wsCNOs) isolated from wood wool-a wood-based pyrolysis waste pr... more Water-soluble carbon nano-onions (wsCNOs) isolated from wood wool-a wood-based pyrolysis waste product of wood, can enhance the overall growth rate of gram (Cicer arietinum) plants. Treatment of plants with upto 30 μg mL(-1) of wsCNOs for an initial 10 day period in laboratory conditions led to an increase in the overall growth of the plant biomass. In order to examine the growth stimulating effects of wsCNOs under natural conditions, 10 day-old plants treated with and without wsCNOs were transplanted into soil of standard carbon and nitrogen composition. We observed an enhanced growth rate of the wsCNOs pre-treated plants in soil, which finally led to an increased productivity of plants in terms of a larger number of grams. On analyzing the carbon, hydrogen, and nitrogen (CHN) content for the shoot and fruit sections of the plants treated with and without wsCNOs, only a minor difference in the composition was noticed. However, a slight increase in the percentage of carbon and hydrogen in shoots reflects the synthesis of more organic biomass in the case of treated plants. This work shows that wsCNOs are non-toxic to plant cells and can act as efficient growth stimulants which can be used as benign growth promoters.
Carbon nanocubes and nanobricks were synthesized by pyrolyzing rice powder at 600 degrees C under... more Carbon nanocubes and nanobricks were synthesized by pyrolyzing rice powder at 600 degrees C under nitrogen atmosphere. Purification with concentrated nitric acid introduced approximately 0.1 mol/g of carboxylic acid groups as found by acid-base titrimetric analysis. XRD pattern showed the 0.15 mol/g basic graphitic structure of these nano carbon materials. Their SEM and TEM images revealed cube or brick shaped nano crystals. These nanocrystals are further characterized by FT-IR, Raman, and EDAX analysis. High density wrapping of carboxylated acid groups introduces surface passivation of these nano carbon cubes and nano carbon bricks exhibiting photoluminescence. Solid state electronic spectrum showed several bands in the ultraviolet and visible region and excitation at 336 and 474 nm generates photoluminescence respectively in the ultraviolet and visible region.
Carboxylic acid functionalized water soluble carbon nanotube (wsCNT) shows no toxic effect agains... more Carboxylic acid functionalized water soluble carbon nanotube (wsCNT) shows no toxic effect against the growth of Escherichia-coli (E.coli), a gram-negative bacteria. Treatment up to 8 g mL −1 of wsCNT did not show any toxic effect on E.coli growth that was followed by using bacterial growth kinetics and Spread Plate Technique (SPT). The number of E-coli colonies counts with and without wsCNT showed nearly no change and the bacterial growth kinetics in both the cases showing no toxic effect of wsCNT on the growth of E.coli.
ABSTRACT A low cost synthesis of multicolor fluorescent carbon dots (C-dots) from edible sugars i... more ABSTRACT A low cost synthesis of multicolor fluorescent carbon dots (C-dots) from edible sugars is described here. Common sugars like dextrose, lactose or maltose in aqueous medium gets dehydrated using phosphorus pentoxide (P2O5). The reaction is facile and completed within few minutes to form insoluble carbon (C-dots) mostly having the graphitic (G-band, Raman) sp2 hybridized carbon atoms (C-atoms). This insoluble carbon on oxidative treatment with nitric acid produced disordered sp3 (D-band retaining G-band, Raman) hybridized C-atoms, originated from the graphitic pool with sp2 hybridized C-atoms. This high density assimilation of self passivated "surfacial defects" become emissive during electronic transitions. Surfacial defects due to high degree of electrophilic carboxylation create the water soluble version of multicolor fluorescent C-dots as "water soluble fluorescent carbon dots" (wsFCDs). wsFCDs being itself self-passivated imposes the tunable multicolor emission throughout the visible spectrum without having any external coating and surface passivation and could be used as multicolor fluorescent probe especially in the emerging field of optical bio-imaging.
Black carbon (BC) (as partly burnt black particulate matter) present indoor are deposited on inte... more Black carbon (BC) (as partly burnt black particulate matter) present indoor are deposited on interior surfaces of the indoors (easily visualize over the blades of electric fan/exhausts and over domestic spider webs) are known to be a potential indoor pollution problem. We detect with the help of indoor spider webs the floating BC contains a significant amount of defective multiwalled carbon nanotubes (MWCNTs) possessing room temperature ferromagnetism. Microscopic studies shows a lot of internal and surfacial defects in these indoor-MWCNTs. Electron paramagnetic resonance (EPR) showed the presence of very stable carbon centred radicals in these indoor-MWCNTs. Room temperature ferromagnetism most importantly originated by the presence of a large amount of unpaired spin frustrated carbon centred radicals (trapped in defects, junctions and fractures) which are inadvertently formed during the pyrolysis of carbonaceous materials through routine domestic activities.
Black carbon (BC) emissions have increased over South Asia and more persistent winter fogs are co... more Black carbon (BC) emissions have increased over South Asia and more persistent winter fogs are common during last decade. However, a physical mechanism connecting these two is still unknown. A significant fraction of BC is known to be in the form of carbon-nanotube (CNT). We have investigated the effects of two different sets of fog condensation nuclei, viz., inorganic salts (sodium chloride and ammonium sulphate) and BC (graphite and CNT) on the dissipation of chamber generated fog under dark and halogen lamp illuminated conditions at a controlled temperature, relative humidity, and fog condensation nuclei distribution. We found that, for inorganic salts, fog dissipates at a faster rate under illumination than in dark conditions showing similar trends for both sodium chloride and ammonium chloride. On the contrary, fog is found to be more persistent, for illuminated conditions, in the case of BC. Moreover, fog persistence is found to be more than twice for CNT compared to graphite in illuminated conditions. CNT is known to be an extremely effective absorber of light which leads to microscopic heating and subsequent evaporation which inhibits droplet growth. Small droplets have large residence time leading to longer fog persistence. This hitherto unknown mechanism may be responsible for persistent fog in India during last decade.
Abstract: The nanocrystal structure of a hetero-polyatomic metal-ligand complex,[PPh 4][Ni II (L ... more Abstract: The nanocrystal structure of a hetero-polyatomic metal-ligand complex,[PPh 4][Ni II (L 2−)(L 1−·)],(1)(L= 1, 2-dicarbomethoxyethylene dithiolate) has been arrived at from its molecular structure obtained by X-ray crystallography. The complex (1) exhibits ...
Uploads
Papers by Sumit Sonkar