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Carbon Dots/Nanocellulose Composite for the Colorimetric Detection of Cholesterol
( Rajkumar Bandi ),( Ramakrishna Dadigala ),( Song-yi Han ),( Chan-woo Park ),( Jeong-ki Kim ),( Seung-woo Cho ),( Seo-young Ma ),( Gu-joong Kwon ),( Seung-hwan Lee ) 한국목재공학회 2022 한국목재공학회 학술발표논문집 Vol.2022 No.1
Cholesterol quantification in human serum samples is crucial in disease diagnosis. Colloidal nanozyme based methods suffer from some drawbacks, such as the nanoparticle aggregation in complex biological samples and the development of a biological corona on particle surface, leading to unpredictable results. To address this issue, a facile strategy of immobilizing peroxidase mimicking carbon dots (CDs) on dialdehyde cellulose nanofibrils is proposed for the first time. Fe,N-doped CDs (FeNCDs) with amine functions on its surface were prepared and their peroxidase activity is investigated. Meanwhile, periodate oxidation of the cellulose nanofibrils (CNF) was performed to generate dialdehyde functions on its surface by cleaving C<sub>2</sub>-C<sub>3</sub> of cellulose molecular structure. FeNCDs were immobilized on dialdehyde CNF (DACNF) via Schiff base formation and reductive amination. Colorimetric assays based on 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) oxidation offered linear ranges of 10 - 80 μM and 50 - 400 μM and detection limits of 0.70 and 3.72 μM for H<sub>2</sub>O<sub>2</sub> and cholesterol, respectively. The results of cholesterol detection in human serum samples were in well agreement with those of clinical laboratory.
양이온성 cellulose nanofibril에의 음이온성 carbon dot 흡착을 통한 형광성 에어로겔 제조
( Rajkumar Bandi ),한송이 ( Song-yi Han ),박찬우 ( Chan-woo Park ),박지수 ( Ji-soo Park ),이은아 ( Eun-ah Lee ),김정기 ( Jeong-ki Kim ),( Azelia Wulan ),권구중 ( Cindradewi ),이승환 ( Gu-joong Kwon ),( Seung-hwan Lee ) 한국목재공학회 2020 한국목재공학회 학술발표논문집 Vol.2020 No.1
Preparation of nanocellulose based fluorescent aerogels in which carbon dots (CDs) act as fluorescence source is reported here. In order to create a strong electrostatic interaction between two materials, cellulose nanofibrils (CNF) are first cationized and negatively charged CDs are then adsorbed on it. A rapid microwave-assisted carbonization of citric acid is employed to produce negatively charged CDs. Cationization of CNF is confirmed by FT-IR, <sup>1</sup>H-NMR and zeta potential analysis and formation of negatively charged CDs is confirmed from their zeta potential and fluorescence spectroscopic analysis. As obtained aerogels exhibited bright blue-green emission. Usage of nontoxic CDs instead of conventional heavy metal based quantum dots and organic dyes minimize the safety issues expands the applicability to biomedical fields. Moreover CNF serves as a matrix for dispersing CDs and prevents them from aggregation as well as aggregation caused fluorescence quenching.
( Rajkumar Bandi ),( Chan-woo Park ),( Song-yi Han ),( Azelia Wulan Cindradewi ),( Eun-ah Lee ),( Jeong-ki Kim ),( Gu-joong Kwon ),( Seung-hwan Lee ) 한국목재공학회 2021 한국목재공학회 학술발표논문집 Vol.2021 No.1
Preparation of nanocellulose-based hydrogels that can be used in the field of biomedicine, have gained tremendous attention. Carbon dots are the latest addition to the carbon nanomaterials family and are well known for their stable fluorescence and high biocompatibility. Hence the incorporation of carbon dots into the nanocellulose-based hydrogels can broaden their applicability. In this work, a facile one-pot hydrothermal method is demonstrated to prepare N-doped carbon dots/holocellulose nanofibrils composite (NCDs/HCNF) hydrogel. During the hydrothermal treatment, the NCDs grow in-situ on HCNF surface and serve as cross-linkers to produce hydrogel. Hemicellulose portion of HCNF act as carbon source and ethylenediamine will serve as N dopant. Synthesis conditions were optimized, optical and physicochemical properties were studied in detail.
One-Pot Synthesis of Ag Nanoparticles/Carbon Dots/Holocellulose Nanofibrils Ternary Nanocomposite
( Rajkumar Bandi ),( Chan-woo Park ),( Song-yi Han ),( Azelia Wulan Cindradewi ),( Eun-ah Lee ),( Jeong-ki Kim ),( Gu-joong Kwon ),( Seung-hwan Lee ) 한국목재공학회 2021 한국목재공학회 학술발표논문집 Vol.2021 No.1
Research on development of sustainable and environmentally friendly nanocomposites is a fast growing field due to their potential applications from the combination of unique chemical, optical and mechanical characteristics. Nanocellulose has a great potential to act as a sustainable support material for the formation of various nanocomposites. In this work, a novel ternary composite consisting of Ag nanoparticles, carbon dots and holocellulose nanofibrils (AgNPs/CDs/HCNF) is prepared by a one-pot hydrothermal treatment. During the reaction, AgNPs and CDs were grown in-situ on HCNF. Hemicellulose is crucial for the formation of CDs and AgNPs which was evident from control experiments using pure cellulose nanofibrils. Synthesis conditions were optimized, optical and physicochemical properties of the composite were studied in detail.
Preparation and Characterization of Dicarboxylate Cellulose Nanofibrils/Carbon Dots Nanocomposite
( Rajkumar Bandi ),( Ramakrishna Dadigala ),( Song-yi Han ),( Chan-woo Park ),( Jeong-ki Kim ),( Seung-woo Cho ),( Seo-young Ma ),( Gu-joong Kwon ),( Seung-hwan Lee ) 한국목재공학회 2022 한국목재공학회 학술발표논문집 Vol.2022 No.1
Preparation of a novel nanocomposite of dicarboxylate cellulose nanofibrils/carbon dots (DCNF/CDs) is reported here. A sequential periodate and chlorite oxidation reactions followed by mechanical disintegration of pulp fibers produced DCNF. Periodate oxidation regioselectively cleaved the C2-C3 bond to oxidize the vicinyl hydroxyls to aldehydes that was confirmed by the appearance of carbonyl peak at 1740 cm-1 in FT-IR spectrum and decrease in crystallinity. Chlorite oxidation facilely converted C2, C3 dialdehydes to dicarboxylates and a carboxyl content of 1.13 mM per gram fiber was achieved. Fluorescent CDs with amine functions were prepared by the hydrothermal treatment of polyethylenimine (PEI) and citric acid at 180 ℃ for 6 h. CDs exhibited bright blue emission (λem 445 nm; λex 360 nm) and a fluorescence quantum yield of 12.5%. The DCNF/CDs nanocomposite was obtained by simple mixing of DCNF and CDs. The binding interactions between DCNF and CDs involved electrostatic attractions and amide bond formation.
Immobilization of Fe,N-Doped Carbon Dots on Dialdehyde Cellulose Nanofibrils
( Rajkumar Bandi ),( Ramakrishna Dadigala ),( Chan-woo Park ),( Song-yi Han ),( Azelia Wulan Cindradewi ),( Jeong-ki Kim ),( Gu-joong Kwon ),( Seung-Hwan Lee ) 한국목재공학회 2021 한국목재공학회 학술발표논문집 Vol.2021 No.2
Preparation of a novel nanocomposite of dialdehyde cellulose nanofibrils (DACNF) and Fe,N-doped carbon dots (FeNCDs) is reported here. Periodate oxidation of cellulose nanofibrils (CNF) is performed to produce dialdehyde functions. In a typical reaction, 100 g of 0.5% CNF is reacted with 500 mg sodium periodate at 45 °C temperature for 4 hours under dark conditions. As produced DACNF have an aldehyde content of 1.25 mM/g and yield was above 90%. Periodate oxidation was further characterized by the appearance carbonyl peak in Fourier transform infrared spectra (FT-IR) and reduction in crystallinity index (CI). FeNCDs with surface amine functional groups were prepared by a hydrothermal reaction of citric acid, FeCl<sub>2</sub>.4H<sub>2</sub>O and ethylene diamine at 160 °C for 4 h. Addition of FeNCDs to DACNF resulted in the spontaneous binding of amine functions of FeNCDs to aldehyde functions of DACNF via Schiff base reaction. As formed imine bond was further reduced to stable amine bond by reductive amination with picoline borane. DACNF, FeNCDs and the nanocomposite were thoroughly characterized and binding of FeNCDs to DACNF was confirmed by X-ray photoelectron spectroscopic (XPS) analysis.
( Rajkumar Bandi ),한송이,박찬우,박지수,이은아,( Azelia Wulan Cindradewi ),권구중,이승환 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
A novel green method offering the simultaneous production of silver nanoparticles (AgNPs) and AgNPs decorated holocellulose nanofibrills (AgNPs/HCNF) is reported here. This method is rapid (60 sec) and devoid of additional reducing agent. Synthetic conditions were optimized using UV-vis spectroscopy. Morphological features and crystal structure of as obtained nanomaterials were unveiled by transmission electron microscopy (TEM) and powder X-ray diffraction (XRD) techniques. Surface chemical composition was studied by X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared (FT-IR) spectroscopy. Mechanistic studies revealed the crucial role of hemicellulose in the reduction and stabilization of AgNPs.