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In this study, the fruit of Terminalia chebula, commonly known as chebulic myrobalan, is used as the precursor for carbon for its application in supercapacitors. The Terminalia chebula biomass-derived sponge-like porous carbon (TC-SPC) is synthesized using a facile and economical method of pyrolysis. TC-SPC thus obtained is subjected to XRD, FESEM, TEM, HRTEM, XPS, Raman spectroscopy, ATR-FTIR, and nitrogen adsorption-desorption analyses for their structural and chemical composition. The examination revealed that TC-SPC has a crystalline nature and a mesoporous and microporous structure accompanied by a disordered carbon framework that is doped with heteroatoms such as nitrogen and sulfur. Electrochemical studies are performed on TC-SPC using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. TC-SPC contributed a maximum specific capacitance of 145 F g -1 obtained at 1 A g -1 . The cyclic stability of TC-SPC is significant with 10,000 cycles, maintaining the capacitance retention value of 96%. The results demonstrated that by turning the fruit of Terminalia chebula into an opulent product, a supercapacitor, TC-SPC generated from biomass has proven to be a potential candidate for energy storage application., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Chebulic Myrobalan is the main ingredient in the Ayurvedic formulation Triphala, which is used for kidney and liver dysfunctions. Herein, natural nitrogen-doped carbon dots (NN-CDs) were prepared from the hydrothermal carbonization of Chebulic Myrobalan and were demonstrated to sense heavy metal ions in an aqueous medium. Briefly, the NN-CDs were developed from Chebulic Myrobalan by a single-step hydrothermal carbonization approach under a mild temperature (200 °C) without any capping and passivation agents. They were then thoroughly characterized to confirm their structural and optical properties. The resulting NN-CDs had small particles (average diameter: 2.5 ± 0.5 nm) with a narrow size distribution (1-4 nm) and a relatable degree of graphitization. They possessed bright and durable fluorescence with excitation-dependent emission behaviors. Further, the as-synthesized NN-CDs were a good fluorometric sensor for the detection of heavy metal ions in an aqueous medium. The NN-CDs showed sensitive and selective sensing platforms for Fe 3+ ions; the detection limit was calculated to be 0.86 μM in the dynamic range of 5-25 μM of the ferric (Fe 3+ ) ion concentration. Moreover, these NN-CDs could expand their application as a potential candidate for biomedical applications and offer a new method of hydrothermally carbonizing waste biomass.

In this study, sustainable, low-cost, and environmentally friendly biomass ( Terminalia chebula ) was employed as a precursor for the formation of nitrogen-doped carbon dots (N-CDs). The hydrothermally assisted Terminalia chebula fruit-derived N-CDs (TC-CDs) emitted different bright fluorescent colors under various excitation wavelengths. The prepared TC-CDs showed a spherical morphology with a narrow size distribution and excellent water dispensability due to their abundant functionalities, such as oxygen- and nitrogen-bearing molecules on the surfaces of the TC-CDs. Additionally, these TC-CDs exhibited high photostability, good biocompatibility, very low toxicity, and excellent cell permeability against HCT-116 human colon carcinoma cells. The cell viability of HCT-116 human colon carcinoma cells in the presence of TC-CDs aqueous solution was calculated by MTT assay, and cell viability was higher than 95%, even at a higher concentration of 200 μg mL -1 after 24 h incubation time. Finally, the uptake of TC-CDs by HCT-116 human colon carcinoma cells displayed distinguished blue, green, and red colors during in vitro imaging when excited by three filters with different wavelengths under a laser scanning confocal microscope. Thus, TC-CDs could be used as a potential candidate for various biomedical applications. Moreover, the conversion of low-cost/waste natural biomass into products of value promotes the sustainable development of the economy and human society.

Recent research is focused on biomass-derived porous carbon materials for energy harvesting (hydrogen evolution reaction) because of their cost-effective synthesis, enriched with heteroatoms, lightweight, and stable properties. Here, the synthesis of porous carbon (PC) materials from lotus seedpod (LP) and lotus stem (LS) is reported by the pyrolysis method. The porous and graphitic structure of the prepared LP-PC and LS-PC materials were confirmed by field emission scanning electron microscopy, transmission electron microscopy with selected area electron diffraction, X-ray diffraction, and nitrogen adsorption-desorption measurements. Heteroatoms in LP-PC and LS-PC materials were investigated by attenuated total reflection-Fourier transform infrared and X-ray photoelectron spectroscopy. The specific surface area of LP-PC and LS-PC were calculated as 457 and 313 m 2  g -1 , respectively. Nitrogen and sulfur enriched LP-PC and LS-PC materials were found to be effective electrocatalysts for hydrogen evolution reactions. LP-PC catalyst showed a very low overpotential of 111 mV with the Tafel slope of 69 mV dec -1, and LS-PC catalyst achieved a Tafel slope of 85 mV dec -1 with a low overpotential of 135 mV. This work is expected to be extended for the development of biomass as a sustainable porous carbon electrocatalyst with a tunable structure, elements, and electronic properties. Furthermore, preparing carbon materials from the biowaste and applying clean energy harvesting might reduce environmental pollution., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Heteroatom functionalization on a graphene surface can endow the physical and structural properties of graphene. Here, a one-step in situ polymerization method was used for the noncovalent functionalization of a graphene surface with poly- N -vinyl-2-pyrrolidone (PNVP) and the exfoliation of graphite into graphene sheets. The obtained graphene/poly- N -vinyl pyrrolidone (GPNVP) composite was thoroughly characterized. The surface morphology of GPNVP was observed using field emission scanning electron microscopy and high-resolution transmission electron microscopy. Raman spectroscopy and X-ray diffraction studies were carried out to check for the exfoliation of graphite into graphene sheets. Thermogravimetric analysis was performed to calculate the amount of PNVP on the graphene surface in the GPNVP composite. The successful formation of the GPNVP composite and functionalization of the graphene surface was confirmed by various studies. The cyclic voltammetry measurement at different scan rates (5-500 mV/s) and electrochemical impedance spectroscopy study of the GPNVP composite were performed in the typical three-electrode system. The GPNVP composite has excellent rate capability with the capacitive property. This study demonstrates the one-pot preparation of exfoliation and functionalization of a graphene surface with the heterocyclic polymer PNVP; the resulting GPNVP composite will be an ideal candidate for various electrochemical applications.

Nitrogen-doped carbon dot decorated zinc oxide nanoparticles (N-CDs@ZnO composite) were successfully fabricated by an economical wet-impregnation method and used as a photocatalyst for the degradation of aqueous methylene blue (MB) dye under UV-light at room temperature. The chemical composition and morphological features of the prepared N-CDs@ZnO composite were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The photodegradation capability of the N-CDs@ZnO composite was compared with that of bare ZnO nanoparticles, under identical experimental conditions. The results show that the N-CDs@ZnO composite exhibits notably higher photocatalytic activity (degradation efficiency over 99%, 60 min) compared to bare ZnO nanoparticles (75%, 60 min) towards the degradation of MB under UV-light irradiation. Besides, the degradation obeyed the pseudo-first-order kinetics model with a photocatalytic rate constant (k) of 0.0557 min-1, which was ∼2.3 times higher than that of bare ZnO nanoparticles (0.0240 min-1). The crucial roles of N-CDs in the enhancement of the photocatalytic activity of the N-CDs@ZnO composite arise because the N-CDs can efficiently absorb UV-light and trap electrons, thus hindering the recombination of the photo-generated electron-hole pairs and also suppressing the photocorrosion of the ZnO nanoparticles in the N-CDs@ZnO composite. The N-CDs@ZnO composite not only showed good photocatalytic activity but also had good stability since the photocatalytic activity did not significantly decrease after three cycling tests. The present study shows that the N-CDs@ZnO composite can be considered as an ideal photocatalyst in the field of dye degradation. Overall, the present approach obeys green chemistry principles with the simple construction of the N-CDs@ZnO composite and the composite holds promise for the development of efficient photocatalytic systems.

Cancer is becoming a major reason for death troll worldwide due to the difficulty in finding an efficient, cost effective and target specific method of treatment or diagnosis. The variety of cancer therapy used in the present scenario have painful side effects, low effectiveness and high cost, which are some major drawbacks of the available therapies. Apart from the conventional cancer therapy, nanotechnology has grown extremely towards treating cancer. Nanotechnology is a promising area of science focusing on developing target specific drug delivery system for carrying small or large active molecules to diagnose and treat cancer cells. In the field of nanoscience, Chitosan nanopolymers (ChNPs) are been emerging as a potential carrier due to their biodegradability and biocompatibility. The easy modification and versatility in administration route of ChNPs has attracted attention of researchers towards loading chemicals, proteins and gene drugs for target specific therapy of cancer cells. Therefore, the present review deals with the growing concern towards cancer therapy, introduction of ChNPs, mode of action and other strategies employed by researchers till date towards cancer treatment and diagnosis ChNPs., (Copyright © 2019 Elsevier B.V. All rights reserved.)

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 2 NPs) followed by the covalent immobilization of glucose oxidase (GODx) on them (designated as a GODx/NDC-TiO 2 NPs/ITO biosensor). Initially, the TiO 2 NPs was synthesized by sol-gel method and then NDC-TiO 2 NPs was synthesized utilizing a green source of Prunus persica (peach fruit) through a simple hydrothermal process. The synthesized NDC-TiO 2 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 2 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 2 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., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The present work illustrates the potential uses of nitrogen-doped multi-fluorescent carbon dots (N-CDs) for Fe 3+ sensing, cellular multi-colour imaging, and fluorescent ink. N-CDs were synthesized using Magnolia liliiflora flower by the simple hydrothermal method. The resulted N-CDs was found to be nearly spherical in shape with the size of about 4 ± 1 nm and showed competitive quantum yield around 11%. The synthesized N-CDs with uniform size distribution and high content of nitrogen and oxygen-bearing functional groups exhibit excellent dispersibility in aqueous media. The N-CDs were able to detect a high concentration of Fe 3+ ions (1-1000 μM) with a limit of detection is about 1.2 μM by forming N-CDs-Fe 3+ complex due to the functional groups such as nitrogen, carbonyl and carboxyl on the surface of N-CDs. Thus they could be used to remove pollutants from industrial wastewater. The electronic charge on the surface of the N-CDs and N-CDs-Fe 3+ complex (zeta potential) is around -36 and 18 mV, respectively. In addition, these N-CDs show excitation-dependent fluorescence that was utilized for multi-colour in vitro cellular imaging in rat liver cells (Clone 9 hepatocytes). The N-CDs are rapidly uptake in the cell cytoplasm and showed high cytocompatibility on cellular morphology. Moreover, as the N-CDs possess strong fluorescence and anti-coagulation they could be utilized in fluorescent ink pens., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Doxorubicin (Dox) is a valuable anticancer drug for hematologic and solid tumors. Yet, it can cause multi-organ toxicities in various patients. Since toxicity evaluation is a major criterion to discuss for every experiment, the current mini-review focuses on the toxicity of Dox to multiple organs and suggests the most probable mechanism. Though several mechanisms have been suggested, the role of oxidative stress remains elusive among other mechanisms and remains the most probable mechanism for cardiotoxic effect of Dox., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Cancer is an abnormal condition leading to uncontrolled cell division which causes damage to the body tissues. Around 100 types of cancer are studied so far namely breast cancer, lung cancer, skin cancer, prostate cancer, colon cancer and lymphoma. Major cancer therapies include chemotherapy, surgery and radiations but their major drawbacks are non-specifically distributed antitumor agents, uneven delivery of drug concentration to the tumour and low monitoring. Nanoparticles (NPs) are the newly trending field of nanomedicine implied in cancer therapy. The structural characteristics of NPs makes them excellent mode for targeting and penetrating the abnormal cell growth caused by cancer. They can potentially enter the abnormal cells causing DNA damage and determine the defects in the genes. Apart from targeting cancer cells they also aid in drug delivery, imaging of abnormal cells, release and monitoring of therapeutic agents against cancer. The present review deals with the inorganic NPs mediated pharmacotherapy, potential strategies for developing drug delivery system, evaluate the merits and demerits of traditional chemotherapy and nanotherapy for significantly improving the treatment of cancers., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A facile, economical and one-step hydrothermal method is used to synthesize highly durable fluorescent nitrogen-doped carbon dots (FNCDs) by utilizing Phyllanthus acidus (P. acidus) 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 3+ . Based on the linear relationship between normalized fluorescence intensity and concentration of Fe 3+ ions, the prepared FNCDs can be used for label-free sensitive and selective detection of Fe 3+ 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 3+ , fluorescent ink and cellular imaging with good biocompatibility and low cytotoxicity., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This paper reports the robust hydrothermal synthesis of nitrogen doped carbon dots (N-CDs) using the unripe fruit of Prunus persica (peach) as the carbon precursor and aqueous ammonia as the nitrogen source. The optical properties of synthesized N-CDs were characterized by ultraviolet visible (UV-Vis) and fluorescence spectroscopy techniques. The synthesized N-CDs were emitted blue light when excitated with a portable UV lamp. The materials with the optical properties were characterized further by high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), Raman, Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). The mean size of the N-CDs was approximately 8nm, as calculated from the HRTEM image. The d-spacing of N-CDs, calculated using Bragg law, was approximately 0.21nm, which was consistent with the interlayer distance calculated from the HRTEM image. FT-IR spectroscopy and XPS revealed the presence of the phytoconstituents functionalities of peach fruit over the N-CDs surface and a high level of nitrogen doping on carbon dots (CDs) was confirmed by XPS studies. These results suggest that the unripe fruit extract of peach is an ideal candidate for the preparation of N-CDs. The resulting N-CDs showed excellent optical properties in water. The synthesized N-CDs exhibited a high fluorescence quantum yield and low cytotoxicity, and can be used as fluorescence imaging probes. In addition, the N-CDs were catalytically activite towards the oxygen reduction reaction (ORR). The N-CDs exhibited good catalytic activity in an alkaline medium (0.1M KOH) with a remarkable ORR of approximately 0.72V vs reversible hydrogen electrode (RHE), and O2 reduction follows mainly a 2 electron pathway by being reduced to hydrogen peroxide. The 2-electron reduction pathway is used in industry for H2O2 production., (Copyright © 2016 Elsevier Inc. All rights reserved.)

In the present work, reductive-degradation of azo dyes such as congo red (CR) and methyl orange (MO) was manifested using Anacardium occidentale testa derived silver nanoparticles (AgNPs) as a catalyst. The formation of highly stable AgNPs were visually confirmed by the appearance of yellow color and further substantiated by the existence of surface plasmon resonance (SPR) peak around 425nm. The effect of A. occidentale concentration, reaction time and pH in the formations of AgNPs was corroborated by UV-visible (UV-Vis) spectroscopy. The Fourier transform infrared (FT-IR) spectroscopic results proved that phytoconstituents of A. occidentale testa acts as a capping agent and thereby protects the AgNPs from aggregation. The crystalline nature of the AgNPs was validated from the XRD patterns. The average size of synthesized AgNPs was 25nm, with distorted spherical shape was ascribed from the high resolution transmission electron microscopic (HR-TEM) images. Due to the high stability of the as-synthesized AgNPs, they were utilized for the degradation of carcinogenic azo dyes such as CR and MO using NaBH4 and its catalytic activity was studied via UV-Vis spectroscopy. The results proved that extraordinary catalytic activity of synthesized AgNPs towards the reductive-degradation of both CR and MO., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Zinc oxide nanoparticles decorated graphene oxide (ZnO@GO) composite was synthesized by simple solvothermal method where zinc oxide (ZnO) nanoparticles and graphene oxide (GO) were synthesized via simple thermal oxidation and Hummers method, respectively. The obtained materials were thoroughly characterized by various physico-chemical techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Raman spectrum shows the intensity of D to G value was close to one which confirms the obtained GO and ZnO@GO composite possesses moderate graphitization. TEM images shows the ZnO nanoparticles mean size of 15±5nm were dispersed over the wrinkled graphene layers. The photocatalytic performance of ZnO@GO composite on degradation of methylene blue (MB) is investigated and the results show that the GO plays an important role in the enhancement of photocatalytic performance. The synthesized ZnO@GO composite achieves a maximum degradation efficiency of 98.5% in a neutral solution under UV-light irradiation for 15min as compared with pure ZnO (degradation efficiency is 49% after 60min of irradiation) due to the increased light absorption, the reduced charge recombination with the introduction of GO. Moreover, the resulting ZnO@GO composite possesses excellent degradation efficiency as compared to ZnO nanoparticles alone on MB., (Copyright © 2016 Elsevier B.V. All rights reserved.)