Browsing by Author "Shellaiah, Muthaiah"

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A new pyrene-based aggregation induced ratiometric emission probe for selective detections of trivalent metal ions and its living cell application
(2015-02-01)
Singh, Ashutosh
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Singh, Ravinder
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Shellaiah, Muthaiah
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Prakash, Epperla Chandra
;
Chang, Huan-Cheng
We synthesize a newly designed pyrene-based fluorescent probe FBP containing a Schiff base and amide linkage as a receptor, which demonstrates selective UV-vis and fluorometric detections of trivalent metal ions in various semi-aqueous solution conditions. Interestingly, by increasing water contents the aggregation induced ratiometric emissions (AIREs) of photoluminescence in FBP solutions (in DMSO/H2O) are enhanced from blue to green due to the excimer formation of the aggregates in water. In addition, the enhanced aggregated ratiometric green fluorescence behaviors of FBP in the presence of trivalent metal ions (Al3+, Fe3+, and Cr3+) are observed in semi-aqueous solutions as well as the solid state, which is well utilized to detect trivalent metal ions in living cells. Further verification of the probe detections, their interactions toward trivalent metal ions are well characterized by the time-resolved photoluminescence (TRPL) of spectroscopic responses as well as theoretical calculations. Therefore, we believe the application of such a new AIRE-based approach is first reported among Schiff base and pyrene-based fluorescentchemo- and bio-sensors. (C) 2014 Elsevier B.V. All rights reserved.
A simple pyrene based AIEE active schiff base probe for selective naked eye and fluoresence off-on detection of trivalent cations with live cell application
(2016-08)
Simon, Turibius
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Shellaiah, Muthaiah
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Srinivasadesikan, Venkatesan
;
Lin, Ching-Chang
;
Ko, Fu-Hsiang
A simple pyrene based schiff base derivative 2-((pyren-1-ylmethylene)amino)ethanol (PE) has been synthesized via one-pot reaction and its nano-aggregation induced emission enhancement (AIEE) was reported through UV/PL, TEM and DLS studies. Interestingly, PE in CH3CN revealed the naked eye and fluorescence turn-on sensing responses towards Fe3+, Cr3+ and Al3+ ions, by means of PET and PE-PE* excimer formation. The 2:1 stoichiometry of sensor complexes PE-M3+ (M=Fe/Cr/Al) were calculated from Job\'s plots based on UV-vis absorption titrations and supported by FTIR and ESI (+Ve) mass analysis. In addition, the binding site of PE-M3+ sensor complexes was well established by H-1 NMR titrations and its sensor reversibility was recognized during subsequent addition of M3+ ions and PMDTA, respectively. The detection limits (LODs) and the association constant (K-a) values of PE-M3+ complexes were calculated by standard deviation and linear fittings. Likewise, quantum yield (Phi(f)) calculations, TEM analysis, pH effect and density functional theory (DFT) studies were executed for the PE-M3+ sensor complexes. More importantly, confocal fluorescence microscopy imaging in Raw264.7 cells showed that PE could be used as an effective fluorescent probe for detecting Fe3+, Cr3+ and Al3+ ions in living cells. (C) 2016 Elsevier B.V. All rights reserved.
An Affordable Wet Chemical Route to Grow Conducting Hybrid Graphite-Diamond Nanowires: Demonstration by A Single Nanowire Device
(2017-09-11)
Shellaiah, Muthaiah
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Chen, Tin Hao
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Simon, Turibius
;
Li, Liang-Chen
;
Sun, Kien Wen
We report an affordable wet chemical route for the reproducible hybrid graphite-diamond nanowires (G-DNWs) growth from cysteamine functionalized diamond nanoparticles (ND-Cys) via pH induced self-assembly, which has been visualized through SEM and TEM images. Interestingly, the mechanistic aspects behind that self-assembly directed G-DNWs formation was discussed in details. Notably, above self-assembly was validated by AFM and TEM data. Further interrogations by XRD and Raman data were revealed the possible graphite sheath wrapping over DNWs. Moreover, the HR-TEM studies also verified the coexistence of less perfect sp(2) graphite layer wrapped over the sp3 diamond carbon and the impurity channels as well. Very importantly, conductivity of hybrid G-DNWs was verified via fabrication of a single G-DNW. Wherein, the better conductivity of G-DNW portion L2 was found as 2.4 +/- 1.92 x 10(-6) mS/cm and revealed its effective applicability in near future. In addition to note, temperature dependent carrier transport mechanisms and activation energy calculations were reported in details in this work. Ultimately, to demonstrate the importance of our conductivity measurements, the possible mechanism behind the electrical transport and the comparative account on electrical resistivities of carbon based materials were provided.
Cysteamine-capped gold-copper nanoclusters for fluorometric determination and imaging of chromium(VI) and dopamine
(2019-12-01)
Shellaiah, Muthaiah
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Simon, Turibius
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Thirumalaivasan, Natesan
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Sun, Kien Wen
;
Ko, Fu-Hsiang
Highly emissive cysteamine-capped gold-copper bimetallic nanoclusters (CA-AuCu NCs) with a quantum yield of 18% were synthesized via one-pot anti-galvanic reduction. The CA-AuCu NCs were characterized by HR-TEM, XPS, FTIR, MALDI-TOF mass spectrometry, DLS, and zeta potential analyses. The NCs are shown to be viable fluorescent probes for Cr(VI) ions and dopamine (DA) via quenching of the blue fluorescence, typically measured at excitation/emission wavelengths of 350/436 nm. During DA recognition, a dark brown color appears, which is distinguishable from that of Cr(VI) detection. The aggregation induced quenching due to electron transfer was demonstrated by photoluminescence, HR-TEM, FTIR, DLS, and zeta potential interrogations. In buffer of pH 7, response is linear in the 0.2 100 mu M for Cr(VI) and from 0.4 250 mu M for DA. The respective detection limits are 80 and 135 nM. The method was applied to the determination of both Cr(VI) and DA in (spiked) tap, lake and sea water, and in human urine samples. The low toxicity of CA-AuCu NCs was validated by the MTT assay, and their responses to Cr(VI) ions and DA was also proven by Raw 264.7 cell imaging. Graphical abstract Cysteamine capped Au-Cu nanoclusters (CA-AuCu NCs) were synthesized via one-pot anti-galvanic reduction and utilized in sensing of Cr(VI) ions and dopamine (DA) with demonstrated real/urine and cell imaging applications.
Cysteamine-modified diamond nanoparticles applied in cellular imaging and Hg2+ ions detection
(2019-01-28)
Shellaiah, Muthaiah
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Simon, Turibius
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Venkatesan, Parthiban
;
Sun, Kien Wen
;
Ko, Fu-Hsiang
Luminescent cysteamine-modified nanodiamond particles (ND-Cys) have been reported in surface-mediated energy transfer, cell imaging, and metal-ion recognition studies. In normalized photoluminescence (PL) spectral studies, the emission maxima of ND-Cys (at 50 mu g/mL in water) was fixed at 438 nm at 350 nm excitation, producing a blue emission with a quantum yield (Phi) of 0.13. In the dispersion range of 0-800 mu g/mL, ND-Cys exhibited agglomeration-induced energy transfer via red shifting of the PL peak from 438 nm to 451 nm. Analogous to PL studies, Raman interrogations also established the agglomeration and fixed the saturation limit to 500 mu g/mL in water. The low toxicity and biocompatibility of ND-Cys were demonstrated using methyl thiazolyl tetrazolium assay and time-dependent HeLa cell imaging. Subsequently, the Hg2+ selectivity by ND-Cys was revealed by an intense fluorescence peak shift from 440 nm to 463 nm. Fluorescence studies indicated that the detection limit of Hg2+ ions approximated 153 nM. Fourier-transform infrared and X-ray photoelectron spectroscopy (XPS) analyses supported the binding between free thiol (-SH) and amide (-C=O and -NH) groups of ND-Cys to Hg2+. The Hg2+-induced agglomeration and surface graphitization were successfully confirmed by X-ray powder diffraction, XPS, Raman, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, and zeta potential analyses. Effective detection of Hg2+ ions by ND-Cys was validated through HeLa cell imaging at shortened time intervals.
Development of extremely stable dual functionalized gold nanoparticles for effective colorimetric detection of clenbuterol and ractopamine in human urine samples
(2018-09-06)
Simon, Turibius
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Shellaiah, Muthaiah
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Steffi, Perpectual
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Sun, Kien Wen
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Ko, Fu-Hsiang
New glutamic acid (Glu) and polyethylenimine (PE) functionalized ultra-stable gold nanoparticles (PE-Glu-AuNPs) were developed via a simple NaBH4 reduction method. The low toxicity and biocompatibility of PE-Glu-AuNPs were confirmed via an MTT assay in Raw 264.7 cells. Excitingly, PE-Glu-AuNPs were found to be extremely stable at room temperature up to six months and were utilized in an effective colorimetric naked eye assay of clenbuterol (CLB) and ractopamine (RCT) at pH 5. It was found that the selective assay of CLB and RCT is not affected by any other interferences (such as alanine, phenylalanine, NaCl, CaCl2, threonine, cysteine, glycine, glucose, urea and salbutamol). Furthermore, the detection of these beta-agonists can be visually accomplished through change color from wine red to purple blue. Notably, the aggregation induced detection of CLB and RCT was well confirmed through transmission electron microscopy (TEM) and dynamic light scattering (DLS) studies. DLS investigations, clearly showed, that in the presence of CLB and RCT, the initial size of PE-Glu-AuNPs (12.8 +/- 8.6 nm) was changed to 84.8 +/- 52.3 and 79.5 +/- 47.8 nm, respectively, via aggregation. Furthermore, the colorimetric assays of CLB and RCT with PE-Glu-AuNPs were effective starting from CLB and RCT concentrations of 200 nM and 400 nM, respectively, and could be visualized using the naked eyes. Remarkably, UV-vis titrations of PE-Glu-AuNPs with CLB and RCT could be used to well estimate their sub nanomolar detection limits (LODs) via standard deviation and linear fittings. The contribution of surface functional groups that support the analyte recognition was confirmed by fourier-transform infrared spectroscopy (FTIR) analysis. Moreover, the CLB and RCT assays with PE-Glu-AuNPs were supported by examination of human urine samples. (C) 2018 Elsevier B.V. All rights reserved.
Effect of Metal Ions on Hybrid Graphite-Diamond Nanowire Growth: Conductivity Measurements from a Single Nanowire Device
(2019-03-11)
Shellaiah, Muthaiah
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Chen, Ying-Chou
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Simon, Turibius
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Li, Liang-Chen
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Sun, Kien Wen
Novel Cd2+ ions mediated reproducible hybrid graphite-diamond nanowire (G-DNWs; Cd2+-NDS1 NW) growth from 4-Amino-5-phenyl-4H-1,2,4-triazole-3-thiol (S1) functionalized diamond nanoparticles (NDS1) via supramolecular assembly is reported and demonstrated through TEM and AFM images. FTIR, EDX and XPS studies reveal the supramolecular coordination between functional units of NDS1 and Cd2+ ions towards NWs growth. Investigations of XPS, XRD and Raman data show the covering of graphite sheath over DNWs. Moreover, HR-TEM studies on Cd2+-NDS1 NW confirm the coexistence of less perfect sp(2) graphite layer and sp(3) diamond carbon along with impurity channels and flatten surface morphology. Possible mechanisms behind the G-DNWs growth are proposed and clarified. Subsequently, conductivity of the as-grown G-DNWs is determined through the fabrication of a single Cd2+-NDS1 NW device, in which the G-DNW portion L2 demonstrates a better conductivity of 2.31 x 10(-4) mS/cm. In addition, we investigate the temperature-dependent carrier transport mechanisms and the corresponding activation energy in details. Finally, comparisons in electrical resistivities with other carbon-based materials are made to validate the importance of our conductivity measurements.
Facile rhodamine-based colorimetric sensors for sequential detections of Cu(II) ions and pyrophosphate (P2O74-) anions
(2016-01-01)
Arumugaperumal, Reguram
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Srinivasadesikan, Venkatesan
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Lin, Ming-Chang
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Shellaiah, Muthaiah
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Shukla, Tarun
Two rhodamine hydrazine derivatives Rh1 and Rh2 with catechol and ether functionalities have been synthesized and utilized towards sequential colorimetric detections of Cu(II) and pyrophosphate (PPi) ions in CH3CN-H2O (v/v = 9 : 1, 5 mM Tris-HCl, pH 7.4) semi-aqueous medium. Notably, Rh1 and Rh2 are the first example of colorimetric rhodamine-based probes for the sequential detections of Cu2+ ion and PPi anion. Based on the significant colorimetric responses (from colorless to pink) of Rh1 and Rh2 to Cu2+ ions, the detection limits were estimated as low as 1.22 x 10(-8) M and 8.0 x 10(-7) M, respectively, which signified the utilities of designed probes towards facile detections of Cu2+ ions. Furthermore, upon the successive addition of PPi ion to Rh1-Cu2+ and Rh2-Cu2+ complexes, it has been altered and restored to its origin of Rh1 and Rh2 via re-coordination of PPi to Cu2+ ion, which was confirmed by color changes from pink to colorless. Moreover, computational DFT calculations provided more insights into HOMO-LUMO structures of rhodamine derivatives and their copper complexes. Additionally, the solid state strip-based colorimetric detections of Cu2+ ion were supplemented as a real time application.
Field-effect-dependent thermoelectric power in highly resistive Sb2Se3 single nanowire
(2018-04-01)
Sun, Kien Wen
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Ko, Ting-Yu
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Shellaiah, Muthaiah
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應用化學系
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電機學院
In this paper, we report the results of our experiments on and measurements of electrical resistivity and thermoelectric power (Seebeck coefficient) from single-crystalline antimony triselenide (Sb2Se3) single nanowires (NWs) with high resistivity (sigma similar to 4.37 x 10(-4) S/m). A positive Seebeck coefficient of approximately 661 mu V/K at room temperature was obtained using a custom-made thermoelectric power probe with an alternating current lock-in method (the 2 omega technique), which indicates that the thermal transport is dominated by holes. The measured Seebeck coefficient of the NWs is a factor of 2-3 lower than their bulk counterparts and is comparable to that of a highly conductive Sb2Se3 single NWs (approximately -750 mu V/K). We observed an increase in the Seebeck coefficients with increased bias voltages by field-effect gating, which cannot be explained by the modulation of the Fermi level in the NWs.
Improved morphological characteristics and electronic properties of MAPbI(3) thin film with multiple methylamine spray treatments
(2020-03-01)
Chiao, Guan-Haw
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Li, Liang-Chen
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Shellaiah, Muthaiah
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Sun, Kien Wen
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應用化學系
We demonstrated that the quality of the film can be significantly improved by using multiple treatments with methylamine (CH3NH2, MA) spray to the spin-coated perovskite thin films on poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)/ITO glass substrates, leading to more efficient and reproducible photovoltaic and optoelectronic devices. Our X-ray diffraction and scanning electron microscopy measurements indicated an increase in the homogeneity, grain size, and crystallinity of the spin-coated MAPbI(3) thin film after multiple MA vapor treatments. The influence of MA vapor treatments on emission, absorption, energy gap, and carrier lifetime were investigated through the absorption, steady-state, and time-resolved photoluminescence (PL) spectroscopy. The peak position and full width at half maximum of the MA spray-treated film PL were slightly blue shifted and narrowed, respectively, because of the reduced defect states in the band tail and gain boundary. However, the PL intensity of the treated film was lower than that of the untreated one due to the increased carrier diffusivity in larger grains. The carrier type, concentration, mobility, electrical resistivity, and photoconductivity of the MA spray-treated MAPbI(3) thin film was also investigated using the Hall and current-voltage measurements. The improvements in the morphological characteristics and crystallinity of the treated perovskite thin film were reflected in the enhanced carrier mobility, electrical conductivity, photo response, and suppressed carrier recombination.
Naked eye and fluorescent detections of Hg2+ ions and Cysteine via J-aggregation and deaggregation of a perylene bisimide derivative
(2014-04-01)
Fang, Hsiao-Ping
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Shellaiah, Muthaiah
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Singh, Ashutosh
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Raju, Mandapati V. Ramakrishnam
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Wu, Yen-Hsing
Selective naked eye and fluorescent sensor responses of a 1,6,7,12-tetra(4-tert-butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (PBI) derivative are reported for the first time toward Hg2+ ions and Cysteine (Cys) via J-aggregation and deaggregation mechanisms. The J-aggregation and deaggregation of PBI induced by Hg2+ and Cys were well established by UV-vis/PL and H-1 NMR titrations. The 1:1 stoichiometry of PBI-Hg2+ and Cys-Hg2+/PBI ensembles were elucidated from the jobs plots based on their UV-vis spectral changes. The linear complex formation by PBI-Hg2+ ensemble was confirmed through FT-IR and H-1 NMR spectral studies and well supported by its reversible nature upon the addition of pentamethyl diethylene triamine (PMDTA). The positive cooperativities of Hg2+ and Cys (with PBI) in PBI-Hg2+ and Cys-Hg2+/PBI ensembles were evidenced from the Hill plots based on their fluorescence binding isotherms. The detection limits of Hg2+ ions and Cys were calculated as 36.6 and 91.3 nM, respectively, by standard deviations and linear fittings of their Stern-Volmer (KSV) constants and relative fluorescence intensity changes, respectively. Furthermore, the sensor properties of PBI were well investigated by KSV constants, pH values, time effects, and time resolved photoluminescence (TRPL) spectra. (C) 2013 Elsevier B.V. All rights reserved.
Nanodiamonds conjugated to gold nanoparticles for colorimetric detection of clenbuterol and chromium(III) in urine
(2018-01-01)
Shellaiah, Muthaiah
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Simon, Turibius
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Venkatesan, Parthiban
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Sun, Kien Wen
;
Ko, Fu-Hsiang
Nanodiamonds were modified such that they carry thiol groups (ND-thiol). Gold nanoparticles were reacted with ND-thiol to obtain a highly stable conjugate of the type ND@AuNPs. Both ND-thiol and the ND@AuNPs were characterized by SEM, TEM, AFM, DLS, zeta potential, XPS, XRD, UV-Vis, Raman, FTIR and cytotoxicity studies. Their biocompatibility was confirmed via an MTT assay with HeLa cells. At a pH value of 6, the ND@AuNPs represent a colorimetric probe that can be used to selectively detect the illegally used beta-adrenergic drug clenbuterol (CLB) and the pollutant chromium(III). Detection can be performed visually by monitoring the color change from wine red to purple blue, or by colorimetric measurement of the so-called SPR peaks at 651 and 710 nm. The color changes are due to aggregation, and this is confirmed by TEM and DLS data. The involvement of surface functional groups that assist in analyte recognition was verified by FTIR. The detection limits are 0.49 nM for CLB, and 0.37 nM for Cr(III). The ND@AuNPs were successfully applied to the determination of Cr(III) and CLB in spiked human urine samples. Notably, the low interference by other ions in the detection of Cr(III) in tap and lake water is confirmed by ICP-MS analyses.
Novel anthracene- and pyridine-containing Schiff base probe for selective "off-on\'\' fluorescent determination of Cu2+ ions towards live cell application
(2016-07-01)
Simon, Turibius
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Shellaiah, Muthaiah
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Srinivasadesikan, Venkatesan
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Lin, Ching-Chang
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Ko, Fu-Hsiang
The novel anthracene- and pyridine-containing Schiff base derivative 2-(2-(anthracen-9-ylmethylene)-hydrazinyl) pyridine (AP) has been synthesized via one-pot reaction and its fluorescent "off-on\'\' detection of Cu2+ ions, via PET-based mechanism, is reported. The 1 : 1 stoichiometry of AP center dot center dot center dot Cu2+ sensor complex was calculated from Job\'s plot based on PL titrations and supported by ESI (+Ve) mass spectral analysis. In addition, the binding sites of AP center dot center dot center dot Cu2+ sensor conjugate were supported by H-1 NMR titration. The detection limit (LOD) and association constant (Ka) of AP center dot center dot center dot Cu2+ complex were obtained by standard deviation and linear fittings. Furthermore, quantum yield (Ff), SEM analysis, pH effect, FTIR interpretation and density functional theory (DFT) studies were conducted for the AP center dot center dot center dot Cu2+ sensing conjugate. More decisively, confocal fluorescence microscopy imaging from Raw264.7 cells indicated that AP could be used as an effective fluorescent probe for the analysis of Cu2+ ions in living cells.
Novel pyrene containing monomeric and dimeric supramolecular AIEE active nano-probes utilized in selective "off-on" trivalent metal and highly acidic pH sensing with live cell applications
(2016)
Shellaiah, Muthaiah
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Simon, Turibius
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Srinivasadesikan, Venkatesan
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Lin, Chein-Ming
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Sun, Kien Wen
Two novel pyrene containing monomeric and dimeric Schiff base derivatives PCS1 and PCS2 have been synthesized via one-pot reaction and their nano-J-type aggregation induced emission enhancement (AIEE) was well demonstrated using UV-Vis/PL, transmission electron microscopy (TEM), dynamic light scattering (DLS), time resolved photoluminescence (TRPL), and live cell imaging studies. In contrast to PCS2, PCS1 in CH3CN exhibits fluorescence "off-on" sensor selectivity towards transition trivalent metal ions (Fe3+, Cr3+ and Al3+) among other metals, via PET inhibition with excimer PCS1-PCS1(star) formation. The 2 : 1 stoichiometry of PCS1 center dot center dot center dot M3+ (M = Fe/Cr/Al) sensor complexes was calculated from Job\'s plots based on their PL titrations. In addition, the binding sites of PCS1 center dot center dot center dot M3+ sensor complexes were well recognised from the H-1 NMR titrations and supported by ESI(+ve) mass and FTIR analysis. Additionally, fluorescence reversibilities of PCS1 center dot center dot center dot M3+ were observed via consequent addition of M3+ ions and PMDTA, respectively. Furthermore, the detection limits (LODs) and the association constant (K-a) values of PCS1 center dot center dot center dot M3+ complexes were calculated using standard deviation and linear fittings. Likewise, quantum yield (Phi) measurements, TEM analysis, determination of the effect of pH, density functional theory (DFT) and time resolved photoluminescence (TRPL) studies were performed for the PCS1 center dot center dot center dot M3+ sensor complexes. More importantly, confocal fluorescence microscopy imaging of Raw264.7 cells showed that PCS1 could be used as an effective fluorescent probe for detecting transition trivalent metal ions (Fe3+, Cr3+, and Al3+) in living cells. Impressively, both PCS1 and PCS2 showed "off-on" sensing at highly acidic pH values (1-3) with live cell applications.
Novel pyrene- and anthracene-based Schiff base derivatives as Cu2+ and Fe3+ fluorescence turn-on sensors and for aggregation induced emissions
(2013)
Shellaiah, Muthaiah
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Wu, Yen-Hsing
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Singh, Ashutosh
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Raju, Mandapati V. Ramakrishnam
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Lin, Hong-Cheu
Novel pyrene- and anthracene-based Schiff base derivatives P1 and A1 were synthesized via a one-pot reaction and utilized as fluorescence turn-on sensors towards Cu2+ and Fe3+ ions, respectively, and for aggregation induced emissions (AIEs). P1 in CH3CN and A1 in THF illustrated the fluorescence turn-on sensing towards Cu2+ and Fe3+ ions, respectively, via chelation enhanced fluorescence (CHEF) through excimer (P1-P1* and A1-A1*) formation. The 2 : 1 stoichiometry of the sensor complexes (P1 + Cu2+ and A1 + Fe3+) were calculated from Job plots based on UV-Vis absorption titrations. In addition, the binding sites of sensor complexes (P1 + Cu2+ and A1 + Fe3+) were well established from the H-1 NMR titrations and supported by the fluorescence reversibility by adding metal ions and PMDTA sequentially. The detection limits (LODs) and the association constant (K-a) values of P1 + Cu2+ and A1 + Fe3+ sensor responses were calculated by standard deviations, linear fittings and from their fluorescence binding isotherms. More importantly, P1 + Cu2+ and A1 + Fe3+ sensors were found to be active in wide ranges of pHs (1-14 and 2-14, respectively). Moreover, the time effect along with the enhancements of quantum yield (Phi) and time resolved photoluminescence (TRPL) decay constant (tau) towards sensor responses were investigated. Similarly, P1 in CH3CN and A1 in THF showed AIEs by increasing the aqueous media concentration from 0% to 90%, with altered fluorescence peak shifts (red and blue shifts, respectively). As well as tau value enhancements, the Phi values of 0.506 and 0.567 (with 630- and 101-fold enhancements) were acquired for P1 in CH3CN : H2O (20 : 80) and A1 in THF : H2O (40 : 60), respectively.
Pyrene-SH functionalized OTFT for detection of Hg2+ ions in aquatic environments
(2019-06-01)
Rullyani, Cut
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Shellaiah, Muthaiah
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Ramesh, Mohan
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Lin, Hong-Cheu
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Chu, Chih-Wei
Mercury ion (Hg2+) sensor based on bottom gate top contact organic thin film transistor (OTFT) was fabricated. The OTFT channel area was functionalized with pyrene that contain thiol group, which has strong binding affinity toward Hg2+ ion. The OTFT sensor exhibited a charge mobility of 0.28 cm(2) V-1 s(-1), a threshold voltage of -22.3 V and on-to-off ratio 10(3). The sensor shows high selectivity to Hg2+ ion over other two valence metal ions. OTFT sensor exhibited high sensitivity to Hg2+ ion, indicated by increasing of drain current after exposed to different concentration of Hg2+ ion ranging from 1 mM to 0.01 mu M. Moreover, the OTFT sensor capability for practical application was also demonstrated by sensing the present of 25 mu M of Hg2+ ion in tap, drinking and seawater samples.
Review on Nanomaterial-Based Melamine Detection
(2019-02-20)
Shellaiah, Muthaiah
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Sun, Kien Wen
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應用化學系
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電子工程學系及電子研究所
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Department of Applied Chemistry
Illegal adulteration of milk products by melamine and its analogs has become a threat to the world. In 2008, the misuse of melamine with infant formula caused serious effects on babies of China. Thereafter, the government of China and the US Food and Drug Administration (FDA) limited the use of melamine of 1 mg/kg for infant formula and 2.5 mg/kg for other dairy products. Similarly, the World Health Organization (WHO) has also limited the daily intake of melamine of 0.2 mg/kg body weight per day. Many sensory schemes have been proposed by the scientists for carrying out screening on melamine poisoning. Among them, nanomaterial-based sensing techniques are very promising in terms of real-time applicability. These materials uncover and quantify the melamine by means of diverse mechanisms, such as fluorescence resonance energy transfer (FRET), aggregation, inner filter effect, surface-enhanced Raman scattering (SERS), and self-assembly, etc. Nanomaterials used for the melamine determination include carbon dots, quantum dots, nanocomposites, nanocrystals, nanoclusters, nanoparticles, nanorods, nanowires, and nanotubes. In this review, we summarize and comment on the melamine sensing abilities of these nanomaterials for their suitability and future research directions.
Simple bare gold nanoparticles for rapid colorimetric detection of Cr3+ ions in aqueous medium with real sample applications
(2016-04-01)
Shellaiah, Muthaiah
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Simon, Turibius
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Sun, Kien Wen
;
Ko, Fu-Hsiang
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材料科學與工程學系
Facile bare gold nanoparticles (AuNPs) were synthesized via borohydride reduction method and evidenced the colorimetric sensor selectivity to Cr3+ ions among Na+, Ni2+, Fe3+, Cd2+, Cr3+, Cu2+, Ca2+, Mg2+, Ga3+, Fe2+, Ba2+, Al3+ Ag+, Co2+, Zn2+, Pb2+, Mn2+ and Hg2+ ions. The color of bare AuNPs changed rapidly from red to blue via Cr3+ induced aggregation. These Cr3+-induced aggregation of bare AuNPs were monitored by naked eye and using UV-vis spectroscopy. The SPR absorbance (654 nm) of the reaction between bare AuNPs and Cr3+ showed a good linearity with a low detection limit of 13.42 nM. The optimal detection of Cr3+ was achieved between pH ranges from 5 to 11 and its reversibility was well established with EDTA. In addition, the bare AuNPs which were successfully applied for the detection of Cr3+ in tap and lake water displays low interference. (C) 2015 Elsevier B.V. All rights reserved.
Simple pyridyl-salicylimine-based fluorescence "turn-on" sensors for distinct detections of Zn2+, Al3+ and OH- ions in mixed aqueous media
(2013)
Shellaiah, Muthaiah
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Wu, Yen-Hsing
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Lin, Hong-Cheu
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材料科學與工程學系
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Department of Materials Science and Engineering
Simple pyridyl-salicylimine derivatives (F1, F2 and F3) are reported for the first time as fluorescence "turn-on" sensors for distinct detections of Zn2+, Al3+ and OH- ions in mixed-aqueous media CH3CN/H2O with volume ratios of 6/4 and 3/7 (at pH = 7 and 25 degrees C) via internal charge transfer (ICT), chelation enhanced fluorescence (CHEF), and deprotonation mechanisms. F1 and F2 show diverse turn-on sensing applications to Zn2+, Al3+ and OH- ions, but F3 exhibited the fluorescence turn-on sensing to Al3+ and OH- ions in CH3CN/H2O (6/4; vol/vol). F1+Zn2+ and F2+Zn2+ complexes revealed the reversibilities and ratiometric displacements of Zn2+ with ethylene diamine tetra acetic acid (EDTA) and Al3+ ions, respectively, in CH3CN/H2O (6/4; vol/vol). On the other hand, F1, F2 and F3 in CH3CN/H2O (3/7; vol/vol) showed sensitivities only to Al3+ ions but negligible selectivities to OH- ions. Stoichiometry of all sensor complexes were calculated as 1 : 1 by job's plots based on UV/Vis and PL titrations. The complex formation and binding sites of all sensor materials were well characterized by H-1, C-13 NMR, and mass (FAB) spectral analysis. Detection limits were calculated from standard deviations and linear fitting calculations. The association constant (log K-a) values of sensor complexes were evaluated from the fluorescence binding isotherms. The fluorescence decay constant (tau) values were estimated from time resolved fluorescence studies. Time, temperature, pH and solvent concentration effects towards sensor responses were fully investigated in this report.
Star-shaped self-assembly of an organic thin film transistor sensor in the presence of Cu2+ and CN- ions
(2014-02-01)
Ramesh, Mohan
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You, Yuan-Ruei
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Shellaiah, Muthaiah
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Wu, Meng-Chyi
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Lin, Hong-Cheu
In this study we developed organic thin film transistors (OTFTs) for the sensing of metal ions and anions through the self-assembly of a pentacene/Schiff base pyrene derivative. Our bilayer OTFTs displayed attractive device parameters: an electron mobility (mu) of 0.12 cm(2) V-1 s(-1), a threshold voltage (Vth) of 22.20 V, and a five-orders-of-magnitude on/off ratio. This device was sensitive toward Cu2+ among 13 metal cations and toward CN among nine anions, as measured through changes in the values of Vth and I-off in the presence of Cu2+ cations and a change in the value of I-sat in the presence of CN anions. We observed selectivity toward both of these ions in mixed ion solutions, with sensitivity over different concentrations (from 20 to 350 mu M for Cu2+; from 100 to 350 mu M for CN ) as well as in sea water. The pyrene derivative self-assembled through pyrene-pyrene coordination in the presence of Cu2+ ions; the rods of the pyrene derivative broke into smaller pieces upon formation of benzoxazole rings in the presence of CN ions, as confirmed using atomic force microscopy and fourier transform attenuated total reflection spectroscopy. (C) 2013 Elsevier B.V. All rights reserved.