Highly fluorescent nitrogen-doped carbon dots derived from <i>Phyllanthus acidus</i> utilized as a fluorescent probe for label-free selective detection of Fe³⁺ ions, live cell imaging and fluorescent ink

Atchudan, Raji,Edison, Thomas Nesakumar Jebakumar Immanuel,Aseer, Kanikkai Raja,Perumal, Suguna,Karthik, Namachivayam,Lee, Yong Rok Elsevier 2018 Biosensors & bioelectronics Vol.99 No.-

<P><B>Abstract</B></P> <P>A facile, economical and one-step hydrothermal method is used to synthesize highly durable fluorescent nitrogen-doped carbon dots (FNCDs) by utilizing <I>Phyllanthus acidus</I> (<I>P. acidus</I>) and aqueous ammonia as the carbon and nitrogen sources, respectively. The synthesized FNCDs have an average size of 4.5±1nm and showed bright blue fluorescence under the irradiation of UV-light at an excitation wavelength of 365nm. It exhibits a quantum yield (QY) of 14% at an excitation wavelength of 350nm with maximum emission at 420nm. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy characterizations clearly showed the formation of FNCDs that predominantly consists of nitrogen and hydroxyl groups which can provide more adsorption sites. In addition, the above study reveals the successful bonding of nitrogen with carbon (C–N) in the FNCDs. The synthesized FNCDs with high QY can be used as efficient fluorescent probes for the detection of Fe<SUP>3+</SUP>. Based on the linear relationship between normalized fluorescence intensity and concentration of Fe<SUP>3+</SUP> ions, the prepared FNCDs can be used for label-free sensitive and selective detection of Fe<SUP>3+</SUP> ions in a wide concentration range of 2–25μM with a detection limit of 0.9μM. The present study proves that synthesized FNCDs has durable fluorescence, soluble in water very well and thus act as a promising candidate for the diverse applications such as label-free sensitive and selective detection of Fe<SUP>3+</SUP>, fluorescent ink and cellular imaging with good biocompatibility and low cytotoxicity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> FNCDs was successfully synthesized using <I>Phyllanthus acidus</I> by hydrothermal method. </LI> <LI> First time, durable FNCDs was derived from the <I>P. acidus</I> fruit juice with QY of 14%. </LI> <LI> FNCDs were used as a fluorescent probe for lable-free selective detection of Fe<SUP>3+</SUP>. </LI> <LI> FNCDs can be used as a fluorescent ink without any chemical modification. </LI> <LI> FNCDs could offer a multi-colour cell imaging and alternative for fluorescent pens. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Green synthesized multiple fluorescent nitrogen-doped carbon quantum dots as an efficient label-free optical nanoprobe for <i>in vivo</i> live-cell imaging

Atchudan, Raji,Edison, Thomas Nesakumar Jebakumar Immanuel,Perumal, Suguna,Clament Sagaya Selvam, N.,Lee, Yong Rok Elsevier 2019 Journal of photochemistry and photobiology Chemist Vol.372 No.-

<P><B>Abstract</B></P> <P>In this work, nitrogen-doped carbon quantum dots (N-CQDs) have been synthesized successfully by a simple hydrothermal method and demonstrated its application for multicolor imaging in <I>Caenorhabditis elegans</I> (<I>C. elegans</I>) as an <I>in vivo</I> model. The synthesized N-CQDs were characterized by various physicochemical techniques such as XRD, Raman spectroscopy, ATR-FTIR spectroscopy, XPS, HRTEM, UV–vis spectroscopy, and fluorescence spectroscopy. The synthesized N-CQDs exhibited a strong fluorescence due to the uniform size distribution with nitrogen-containing and oxygen-containing functional groups onto the surface of N-CQDs which induce the excellent dispersibility in aqueous media. The N-CQDs has an excitation-dependent fluorescence behavior and the strongest fluorescence appeared at 411 nm (emission peak position) under the excitation of 340 nm. Also, the N-CQDs displayed a high quantum yield (QY) of 12.5. The fluorescence behaviour of the aqueous N-CQDs suspension retains for a long time up to 1 year. The prolonging fluorescent N-CQDs was utilized as a staining agent for bioimaging and toxicity of N-CQDs on <I>C. elegans</I> that was conducted by killing assay. <I>In-vivo</I> studies suggested that the N-CQDs displayed excellent biocompatibility and successfully used for high-contrast imaging of N-CQDs in living and dead <I>C. elegans</I>. Based on the strongest fluorescence along with excellent aqueous dispersibility and biocompatibility, the green synthesized N-CQDs would be an ideal candidate for many biological applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A strongest multiple fluorescent N-CQDs were synthesized from the <I>P. acidus</I> fruits. </LI> <LI> Synthesized N-CQDs showed low-toxic and were employed for <I>in vivo</I> live-cell imaging. </LI> <LI> The N-CQDs were uniformly stained within the body of the nematodes (<I>C. elegans</I>). </LI> <LI> The live-cell imaging result reveals the usage of N-CQDs in drug delivery. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

An ultrasensitive photoelectrochemical biosensor for glucose based on bio-derived nitrogen-doped carbon sheets wrapped titanium dioxide nanoparticles

Atchudan, Raji,Muthuchamy, Nallal,Edison, Thomas Nesakumar Jebakumar Immanuel,Perumal, Suguna,Vinodh, Rajangam,Park, Kang Hyun,Lee, Yong Rok Elsevier 2019 Biosensors & bioelectronics Vol.126 No.-

<P><B>Abstract</B></P> <P>In this work, an ultra-sensing photoelectrochemical (PEC) glucose biosensor has been constructed from the bio-derived nitrogen-doped carbon sheets (NDC) wrapped titanium dioxide nanoparticles (NDC-TiO<SUB>2</SUB> NPs) followed by the covalent immobilization of glucose oxidase (GODx) on them (designated as a GODx/NDC-TiO<SUB>2</SUB>NPs/ITO biosensor). Initially, the TiO<SUB>2</SUB> NPs was synthesized by sol-gel method and then NDC-TiO<SUB>2</SUB> NPs was synthesized utilizing a green source of <I>Prunus persica</I> (peach fruit) through a simple hydrothermal process. The synthesized NDC-TiO<SUB>2</SUB> NPs composite was characterized by FESEM, HRTEM, Raman spectroscopy, XRD, ATR-FTIR spectroscopy and XPS to determine composition and phase purity. These fabricated GODx/NDC-TiO<SUB>2</SUB>NPs/ITO biosensor exhibited a good charge separation, highly enhanced and stable photocurrent responses with switching PEC behavior under the light (λ > 400 nm). As a result, GODx/NDC-TiO<SUB>2</SUB>NPs/ITO PEC glucose sensor exhibits a good photocurrent response to detection of glucose concentrations (0.05–10 μM) with an ultra-low detection limit of 13 nM under optimized PEC experimental conditions. Also, the PEC glucose sensor revealed a high selectivity, good stability, long time durability, and capability to analyze the glucose levels in real human serum. Also, the further development of this work may provide new insights into preparing other bio-derived carbon nanostructure-based photocatalysts for PEC applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> NDC-TiO<SUB>2</SUB> NPs was synthesized hydrothermally utilizing a green source of peach fruit. </LI> <LI> GODx/NDC-TiO<SUB>2</SUB>NPs/ITO biosensor successfully fabricated for PEC electrode material. </LI> <LI> The biosensor delivers a LOD of 13 nM with a wide linear range of 0.05–10 μM. </LI> <LI> Also, the PEC glucose detection in real human blood serum with good recoveries. </LI> <LI> Green source derived PEC biosensor is an ideal platform for other PEC biosensors. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Preparation of CaCO₃ and CaO Nanoparticles via Solid-State Conversion of Calcium Oleate Precursor

Atchudan, Raji,Lone, Nasreena,Joo, Jin American Scientific Publishers 2018 Journal of Nanoscience and Nanotechnology Vol.18 No.3

<P>Calcium carbonate (CaCO3) and monodisperse calcium oxide nanoparticles (CaO NPs) are prepared by the calcination of solid-state calcium oleate precursor in air condition. The effect of calcination temperature on the synthesis of CaCO3 and CaO NPs is examined. The polymorphism is confirmed by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The sample morphologies including their size and size distribution are investigated by field emission scanning electron microscopy (FESEM). Calcination of calcium oleate between 400 and 550 degrees C results in CaCO3 NPs with mean sizes from 82 to 98 nm, whereas monodisperse spherical CaO NPs are obtained at 650 degrees C and an average size is estimated to be 40 nm. Beyond 650 degrees C, the size of CaO NPs increases with broad size distribution. The results of this study provide a novel approach to monodisperse CaCO3 and CaO NPs that can be applied in a variety of fundamental and industrial fields.</P>

In-situ green synthesis of nitrogen-doped carbon dots for bioimaging and TiO₂ nanoparticles@nitrogen-doped carbon composite for photocatalytic degradation of organic pollutants

Atchudan, Raji,Edison, Thomas Nesakumar Jebakumar Immanuel,Perumal, Suguna,Vinodh, Rajangam,Lee, Yong Rok Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.766 No.-

<P><B>Abstract</B></P> <P>As an efficient photocatalytic titanium dioxide nanoparticles@nitrogen-doped carbon (TiO<SUB>2</SUB> NPs@C) nanocomposite and bright fluorescent with good biocompatible nitrogen-doped carbon dots (N-CDs) were synthesized at once by an affordable hydrothermal method. Physicochemical properties of the synthesized materials were examined by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) with energy dispersive X-ray (EDX) and elemental mapping analysis, high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), ultraviolet–visible (UV–vis) spectroscopy and fluorescence spectroscopy. The photocatalytic efficiency of synthesized TiO<SUB>2</SUB> NPs@C nanocomposite was evaluated in the degradation of methylene blue (MB) under UV-light irradiation. The degradation efficiency of TiO<SUB>2</SUB> NPs@C nanocomposite is about 90% when extending the irradiation time to 40 min, the rate constant is 5 times higher than that of bare TiO<SUB>2</SUB> NPs. The augmentation of photocatalytic activity of TiO<SUB>2</SUB> NPs@C nanocomposite was attributed to the synergistic effect between TiO<SUB>2</SUB> NPs and graphene-like carbon within the nanocomposite. The recycling studies were conducted and the photodegradation efficiency of TiO<SUB>2</SUB> NPs@C nanocomposite did not show any significant changes up to three cycles, suggesting that the synthesized photocatalyst has good repeatability and the considerable stability. In addition, the carbon derived from a natural green source possesses the hydroxyl and nitrogen-containing functional groups on the surface which resulting TiO<SUB>2</SUB> NPs @C nanocomposite with high photocatalytic activity. Also, the obtained N-CDs displays almost zero toxicity towards the <I>Candida albicans</I> cells even at high concentrations which can be utilized as a powerful in-vitro label-free fluorescent probe for live cell imaging. Based on their bright with stable fluorescence and cellular imaging with good biocompatibility, N-CDs would offer a great potential for a wide range of applications in the biomedical and clinical applications in the near future.</P> <P><B>Highlights</B></P> <P> <UL> <LI> TiO<SUB>2</SUB> NPs@C composites was prepared from peach fruit by simple hydrothermal process. </LI> <LI> Degradation efficiency of TiO<SUB>2</SUB> NPs@C is >90% within 40 min under UV irradiation. </LI> <LI> Kinetic of TiO<SUB>2</SUB> NPs@C is 5 times faster than that of TiO<SUB>2</SUB> NPs on MB degradation. </LI> <LI> The obtained N-CDs displays the bright fluorescence with good biocompatibility. </LI> <LI> Based on bioactivity, N-CDs would offer some clinical applications in near future. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Green synthesis of nitrogen-doped carbon nanograss for supercapacitors

Atchudan, Raji,Edison, Thomas Nesakumar Jebakumar Immanuel,Perumal, Suguna,Thirukumaran, Periyasamy,Vinodh, Rajangam,Lee, Yong Rok Elsevier 2019 Journal of the Taiwan Institute of Chemical Engine Vol.102 No.-

<P><B>Abstract</B></P> <P>In the present study, a novel N-doped carbon nanograss (NCNG) were synthesized from the used baby-diaper absorbent via carbonization under the argon atmosphere and has been applied as an electroactive material for flexible supercapacitor. The synthesized NCNG display a grass-like morphology with an acceptable degree of graphitization. The surface areas and average pore size of NCNG were 183 m<SUP>2</SUP> g<SUP>−1</SUP> and 3.3 nm, respectively. On the basis of good structural ordering with reasonable surface area, the NCNG was coated on a carbon cloth and studied their electrochemical performance toward the supercapacitors. The obtained quasi-rectangular shaped cyclic voltammetry curves indicate good capacitive behavior of the NCNG. The galvanostatic charge-discharge experimental results showed that the specific capacitance of NCNG was 81 F g<SUP>−1</SUP> at a current density of 0.5 A g<SUP>−1</SUP> with capacitance retention of 95% after 10,000 cycles of charge-discharge. The slow decrements of specific capacitance with the increment of current density indicate superior rate capability of synthesized NCNG. These excellent electrochemical performances of the synthesized NCNG from used (waste) baby-diaper extend their potential applications in various nanoelectronics field. To the best of authors knowledge, first time the NCNG synthesized from the garbage-waste and can extend their synthesis in large-scale.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The first time, N-doped carbon nanograss was synthesized using used baby-diaper. </LI> <LI> The synthesized NCNG is good structural ordering with a reasonable surface area. </LI> <LI> NCNG delivered a high specific capacitance with good capacitance retention. </LI> <LI> In addition, NCNG from used baby-diaper extend their synthesis in large-scale. </LI> <LI> Importantly, the waste diaper derived energy storage is alternative clean energy. </LI> </UL> </P>

Synthesis and characterization of graphenated carbon nanotubes on IONPs using acetylene by chemical vapor deposition method

Atchudan, R.,Perumal, S.,Edison, T.N.J.I.,Pandurangan, A.,Lee, Y.R. North-Holland 2015 Physica E, Low-dimensional systems & nanostructure Vol.74 No.-

The graphenated carbon nanotubes (G-CNTs) were synthesized on monodisperse spherical iron oxide nanoparticles (IONPs) using acetylene as carbon precursor by simple chemical vapor deposition method. The reaction parameters such as temperature and flow of carbon source were optimized in order to achieve G-CNTs with excellent quality and quantity. Transmission electron microscopy (TEM) clearly illustrated that the graphene flakes are forming along the whole length on CNTs. The degree of graphitization was revealed by X-ray diffraction (XRD) analysis and Raman spectroscopic techniques. The intensity of D to G value was less than one which confirms the obtained G-CNTs have high degree of graphitization. The optimum reaction temperature for the IONPs to form metallic clusters which in turn lead to the formation of G-CNTs with high carbon deposition yield is at 900<SUP>o</SUP>C. The TEM shows the CNTs diameter is 50nm with foiled graphene flakes of diameter around 70nm. Our results advocate for IONPs as a promising catalytic template for quantitative and qualitative productivity of nanohybrid G-CNTs. The produced G-CNTs with high degree of graphitization might be an ideal candidate for nanoelectronic application like super capacitors and so on.

Synthesis and characterization of graphitic mesoporous carbon using metal-metal oxide by chemical vapor deposition method

Atchudan, R.,Perumal, S.,Karthikeyan, D.,Pandurangan, A.,Lee, Y.R. Elsevier 2015 Microporous and mesoporous materials Vol.215 No.-

<P>Mn/MgO was prepared by wet impregnation method and was used as a catalytic template for the growth of graphitic mesoporous carbon (GMC) using acetylene gas as carbon precursor at 900 degrees C by CVD method. The deposited carbon nanostructured material was separated from the catalytic template by the acid treatment, and was investigated by various physico-chemical techniques such as XRD, BET, SEM, TEM, and Raman spectroscopy. The BET surface area of GMC is ca. 200 m(2) g(-1). The XRD pattern and Raman spectroscopic techniques revealed the crystallinity and the degree of graphitization of mesoporous carbon. The interlayer distance of graphene sheet in GMC is around 0.34 nm. All the analytical results strongly support that the prepared mesoporous carbon to be highly ordered and well in graphitic nature. Further, the results demonstrate that the GMC synthesized by using a Mn/MgO might be a promising contender for the large-scale synthesis. (C) 2015 Elsevier Inc. All rights reserved.</P>

Facile green synthesis of nitrogen-doped carbon dots using <i>Chionanthus retusus</i> fruit extract and investigation of their suitability for metal ion sensing and biological applications

Atchudan, Raji,Edison, Thomas Nesakumar Jebakumar Immanuel,Chakradhar, Dasagrandhi,Perumal, Suguna,Shim, Jae-Jin,Lee, Yong Rok Elsevier 2017 Sensors and actuators. B, Chemical Vol.246 No.-

<P><B>Abstract</B></P> <P>Nitrogen-doped carbon dots (N-CDs) were synthesized from <I>Chionanthus retusus (C. retusus)</I> fruit extract using a simple hydrothermal-carbonization method. Their ability to sense metal ions, and their biological activity in terms of cell viability and bioimaging applications were evaluated. The resulting N-CDs were characterized by various physicochemical techniques such as high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy. The optical properties were characterized by ultraviolet visible (UV-vis) fluorescence spectroscopy techniques. The average size of the N-CDs was approximately 5±2nm with an interlayer distance of 0.21nm, as calculated from the HRTEM images. The presence of phytoconstituent functionalities and the percentages of components in the N–CDs were confirmed by XPS studies, and a nitrogen content of 5.3% was detected. The N–CDs demonstrated highly durable fluorescence properties and low cytotoxicity with a quantum yield of 9%. The synthesized N–CDs were then used as probes for the detection of metal ions. The N–CDs exhibited high sensitivity and selectivity towards Fe<SUP>3+</SUP>, with a linear relationship between 0 and 2μM and a detection limit of 70μM. The synthesized N–CDs are anticipated to have diverse biomedical applications, particularly for bioimaging, given their high fluorescence, excellent water solubility, good cell permeability, and negligible cytotoxicity. Finally, the potential of N–CDs as biological probes was investigated using fungal (<I>Candida albicans</I> and <I>Cryptococcus neoformans</I>) strains via fluorescent microscopy. We found that N–CDs were suitable candidates for differential staining applications in yeast cells with good cell permeability, localization with negligible cytotoxicity. Hence, N–CDs may find dual utility as probes for the detection of cellular pools of metal ions (Fe<SUP>3+</SUP>) and also for early detection of opportunistic yeast infections in biological samples.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Durable fluorescent N-CDs prepared using <I>C. Retusus</I> via hydrothermal-carbonization. </LI> <LI> This method of synthesis and N-CDs is an ideal for sensing of Fe<SUP>3+</SUP> and bio-imaging. </LI> <LI> N-CDs was used as a promising fluorescent probe for the direct detection of Fe<SUP>3+</SUP>. </LI> <LI> N-CDs were used as selective probes for yeast <I>C. albicans</I> and <I>C. neoformans</I>. </LI> <LI> N-CDs exhibits selective uptake, good biocompatibility and negligible cytotoxicity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Electrocatalytic and energy storage performance of bio-derived sulphur-nitrogen-doped carbon

Atchudan, Raji,Edison, Thomas Nesakumar Jebakumar Immanuel,Perumal, Suguna,Parveen, Asrafali Shakila,Lee, Yong Rok Elsevier 2019 Journal of Electroanalytical Chemistry Vol.833 No.-

<P><B>Abstract</B></P> <P>Sulphur and nitrogen-rich carbon layers (S/N-CLs) have been derived successfully <I>via</I> a simple calcination for high energy applications including supercapacitor and electrocatalytic hydrogen evolution reaction (HER). The flexible working electrode was fabricated using thoroughly analyzed S/N-CLs composite as an active electrode energy material for supercapacitor and HER. The S/N-CLs composite shows a higher specific capacitance of 266Fg<SUP>−1</SUP> at a current density of 0.5Ag<SUP>−1</SUP> and a satisfied cycling stability with 84% capacitance retention even after 5000cycles of galvanostatic charge-discharge. On the other hand, the synthesized S/N-CLs composite was used as an electrocatalyst for HER and it exhibits an excellent HER performance with an onset overpotential of −75mV, and a Tafel slope of 73mVdec<SUP>−1</SUP> in 0.5M H<SUB>2</SUB>SO<SUB>4</SUB> aqueous electrolyte. Also, the S/N-CLs composite displayed good stability and strong durability. The high electrocatalytic activity and stability of S/N-CLs composite toward HER due to the active site of a compound which may originate from the heteroatom-functional groups including N and S in the carbon structure. Overall, the high-performance supercapacitors and enhancing HER based on heteroatom-doped carbon structures could be promising in replacing traditional supercapacitors for many electronic devices and electrocatalyst for HER.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Conversion of <I>Magnolia liliiflora</I> into S/N-CLs composite by a simple carbonization </LI> <LI> S/N-CLs delivered a higher C<SUB>s</SUB> of 266Fg<SUP>−1</SUP> at 0.5Ag<SUP>−1</SUP> with a satisfied stability. </LI> <LI> S/N-CLs exhibits an excellent HER performance with a Tafel slope of 73mVdec<SUP>−1</SUP>. </LI> <LI> This is the first attempt in synthesis of S/N-CLs using <I>Magnolia liliiflora</I> flower. </LI> <LI> S/N-CLs will be an alternative for traditional energy storage material and electrocatalyst. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>