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Surface Plasmon Enhanced Photoluminescence of Rhodamine B Confined in SBA15
Dinakaran, K.,Chandramohan, A.,Venkatesan, M.R.,Devaraj, S.,Devi, V.,Alagar, M. Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.11
Rhodamine B dye (RB) has been introduced into the mesoporous silica (SBA15) and Ag anchored mesoporous silica by applying solution impregnation method. Surface treatment of SBA15 with 3-aminopropyltrimethoxysilane (APTMS) facilitates selective anchoring of the RB molecules on SBA15. The photoluminescence spectra of RB confined within SBA15 indicates higher emission intensity, than that of the RB solid, particularly in the presence of Ag nanoparticles. The significant enhancement in photoluminescence intensity is attributed to the local enhancement of the optical fields near the molecules by interactions with silver plasmons.
Electrochemical Deposition of Protein-conjugated Graphene by Pulse Reverse Technique
Dinakaran Thirumalai,장승철 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.12
A simple electrochemical deposition method for the immobilization of protein-conjugated graphene onto an electrode has been developed. A unique one-step electrochemical deposition of cytochrome c (Cyt c) conjugated with electrochemically reduced graphene oxide (ErGO) onto the surface of glassy carbon electrode (GCE) without any cross-linkers and the direct electron transfer between Cyt c and the electrode was obtained by the Cyt c–ErGO-modified GCE. The characteristics of the ErGO–Cyt c-modified GCE were compared with those of an ErGO-modified GCE without Cyt c. The direct electron transfer rate constant (ket) was found to be 6.2/s. This approach provides an avenue for the immobilization of various proteins and enzymes with ErGO and could be expanded for diverse biosensor applications.
Dinakaran Thirumalai,Devaraju Subramani,신보성,백현종,장승철 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.2
A new metal-free, non-enzymatic electrochemical sensor system for the detection of glucose was developed in this study. The developed sensor uses a de-bundled single-walled carbon nanotube (SWCNT)-modified glassy carbon electrode (GCE). SWCNTs were de-bundled in aqueous solution by adding a synthesized polymer dispersant, sulfonated poly(ether sulfone). The de-bundled SWCNTs showed two significant characteristics: (1) improvement of the aspect ratio and dispersibility in aqueous solution and (2) suitability for use as a selective and sensitive sensing element in non-enzymatic glucose sensors. The experimental results clearly demonstrated that the SWCNTs/GCE possesses high electro-catalytic activity and efficient sensitivity with a stable and faster amperometric response production. Furthermore, interference by ascorbic acid, acetaminophen, uric acid, and dopamine is effectively avoided. Therefore, the proposed approach is favorable for the design and development of non-enzymatic glucose sensors.
Thirumalai, Dinakaran,Kathiresan, Vijayaraj,Lee, Jaewon,Jin, Sung-Ho,Chang, Seung-Cheol Royal Society of Chemistry 2017 The Analyst Vol.142 No.23
<P>A new amperometric biosensor for hydrogen peroxide (H2O2) and superoxide anion (SO) has been developed. The biosensor developed uses cytochrome <I>c</I> (Cyt <I>c</I>) modified glassy carbon electrodes coupled with electrochemically reduced graphene oxide (ErGO). To immobilize Cyt <I>c</I>, the “one step” electrochemical deposition of vertically aligned and ErGO (VAErGO) has been performed by using a pulse reverse technique, thus resulting in a very simple and efficient system. The well-established vertical alignment of ErGO was confirmed by atomic force microscopy and the electrochemical characteristics of the biosensor were investigated by cyclic voltammetric, electrochemical impedance spectroscopy and amperometric techniques. The surface coverage (<I>Γ</I>) of immobilized Cyt <I>c</I> was effectively increased by the vertical alignment of ErGO and found to be 1.03 × 10<SUP>−10</SUP> mol cm<SUP>−2</SUP>. The direct electron transfer property of Cyt <I>c</I> was also improved by VAErGO and the heterogeneous electron transfer rate constant (<I>k</I>et) was estimated to be 6.40 s<SUP>−1</SUP>. To detect H2O2 and SO, amperometric measurements were carried out at different operating potentials (0.0 V <I>vs.</I> Ag/AgCl for H2O2 and +0.2 V for SO). The sensitivity and detection limit for H2O2 were found to be 46.3 μA mM<SUP>−1</SUP> cm<SUP>−2</SUP> and 2.3 μM, and for SO were found to be 32.1 μM nA<SUP>−1</SUP> cm<SUP>−2</SUP> and 6.84 nM s<SUP>−1</SUP>, respectively. Additionally, the designed biosensor exhibited strong anti-interference ability and satisfactory reproducibility.</P>
Surface Plasmon Enhanced Photoluminescence of Rhodamine B Confined in SBA15
K. Dinakaran,A. Chandramohan,M. R. Venkatesan,S. Devaraj,V. Devi,M. Alagar 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.11
Rhodamine B dye (RB) has been introduced into the mesoporous silica (SBA15) and Ag anchored mesoporous silica by applying solution impregnation method. Surface treatment of SBA15 with 3-aminopropyltrimethoxysilane (APTMS) facilitates selective anchoring of the RB molecules on SBA15. The photoluminescence spectra of RB confined within SBA15 indicates higher emission intensity, than that of the RB solid, particularly in the presence of Ag nanoparticles. The significant enhancement in photoluminescence intensity is attributed to the local enhancement of the optical fields near the molecules by interactions with silver plasmons.
Thirumalai Dinakaran,Subramani Devaraju,Bosung Shin(신보성),Hyun-jong Paik(백현종),Seung-Cheol Chang(장승철) 한국고분자학회 2017 폴리머 Vol.41 No.6
탄소섬유전극을 기반으로 효소가 불필요한 과산화수소(H₂O₂) 센서를 분산된 은 나노와이어와 단일벽 탄소나노튜브를 탄소섬유전극 표면에 드롭캐스팅법으로 고정화하여 제작하였다. 센서 제작에 사용된 탄소나노튜브는 고분자 분산제인 술폰화 폴리(에테르 술폰)에 의하여 효과적인 길이/직경의 종횡비를 나타낼 수 있도록 개별 분산되었으며 센서의 성능 향상을 위하여 은 나노와이어와 더불어 컴포지트 형태로 제작되어 새로운 센서 제작법에 활용되었다. 제작된 센서는 H₂O₂에 대하여 높은 전기촉매활성과 재현성, 빠른 분석 시간 및 우수한 감도를 나타냄을 확인하였다(센서 감도: 1.3 μA·mM<SUP>-1</SUP>, 검출 한계: 0.69 μM (S/N=3) 및 검출 시간: 3초 미만). 따라서 본 연구에서 개발된 고분자 분산제를 사용한 단일벽 탄소나노튜브의 수용액 내에서의 분산도 향상은 효소가 불필요한 H₂O₂ 센서의 설계 및 제작에 활용될 것으로 기대된다. A new non-enzymatic hydrogen peroxide (H₂O₂) sensor based on carbon fiber microelectrodes (CFMEs) has been developed. The CFMEs were modified using a simple drop casting procedure with effectively dispersed silver nanowires (AgNWs) and debundled single-walled carbon nanotubes (SWCNTs). In aqueous solution, the SWCNTs were debundled with a high length/diameter aspect ratio using a synthesized polymer dispersant, sulfonated poly(ether sulfone) (SPES). Enhanced electrocatalytic activity of the sensor for the reduction of H₂O₂ was obtained with the sensor sensitivity of 1.3 μA·mM<SUP>-1</SUP> and the detection limit of 0.69 μM (S/N=3) with a quick turnaround time (less than 3 s). The results clearly reveal that the AgNW-SWCNTs/CFMEs possess high electro-catalytic activity and efficient sensitivity with high reproducibility and fast amperometric response production. Therefore, the proposed debundling approach can be expanded to design and develop nonenzymatic hydrogen peroxide sensors.
Kannaiyan, Dinakaran,Cha, Min-Ah,Jang, Yoon Hee,Sohn, Byeong-Hyeok,Huh, June,Park, Cheolmin,Kim, Dong Ha Royal Society of Chemistry 2009 New journal of chemistry Vol.33 No.12
<P>Well defined, ordered arrays of hybrid Ag/TiO<SUB>2</SUB> hetero nanodots were fabricated on solid substrates using amphiphilic poly(styrene-block-ethylene oxide) diblock copolymer (PS-<I>b</I>-PEO) micelles loaded with AgNO<SUB>3</SUB> and TiO<SUB>2</SUB> sol–gel precursors as templates. The inorganic precursors were selectively incorporated into PEO domains due to specific chemical affinity. The conversion of AgNO<SUB>3</SUB> to metallic Ag was induced by UV irradiation and confirmed by the presence of a surface plasmon band in the UV–vis absorbance spectra. The organic matrix has been removed by deep UV irradiation, leading to arrays of Ag/TiO<SUB>2</SUB> composite nanoparticles (NPs). The morphology and photocatalytic activities of the resulting hybrid nanoparticle arrays were studied. Markedly enhanced photocatalytic degradation of methylene blue has been observed for Ag/TiO<SUB>2</SUB> nanodot arrays compared with pure TiO<SUB>2</SUB> NP arrays.</P> <P>Graphic Abstract</P><P>A facile route to fabricate hybrid TiO<SUB>2</SUB>/Ag nanodot arrays, a promising photocatalytic thin film, utilising cooperative self assembly of a block copolymer and sol–gel precursors is demonstrated. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b9nj00245f'> </P>