Browsing by Author "Simon, Turibius"

Now showing 1 - 13 of 13

A highly sensitive and selective cyanide detection using a gold nanoparticle-based dual fluorescence-colorimetric sensor with a wide concentration range
(2016-05)
Cheng, Chieh
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Chen, Hsueh-Yang
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Wu, Chung-Shu
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Meen, Jagan Singh
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Simon, Turibius
In this study, a simple analytical system is presented for the detection of cyanide with a wide concentration range, which is respectively based on the fluorescent and colorimetric properties of gold nanoparticles. This dual-functional system can work directly for aqueous medium and expand efficiently a wide detection range over three orders of magnitudes for cyanide determination. By using the fluorescence method, the lowest concentration for quantification of cyanide ions is 1.0 x 10(-7) M, and the sensitivity is good enough for the determination of cyanide in drinking water. To recognize higher concentration of cyanide for industrial sewage monitoring, the colorimetric behavior can be used as an alternating tool for field tests from naked eye. The system also provides an excellent selectivity toward cyanide over other common interfering anions and metal ions, thus enabling the ability to monitor cyanide contamination in environmental samples. Furthermore, several real water samples spiked with cyanide, including local tap water, drinking water, lake water, and sea water, were analyzed, and the experimental results demonstrated that this sensing system exhibited excellent recoveries for these practical water samples. Our attempt may provide a cost-effective, rapid and simple solution for the recognition and determination of different levels of cyanide contamination in aqueous samples. (C) 2015 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
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Lin, Ching-Chang
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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
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Li, Liang-Chen
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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
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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
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Sun, Kien Wen
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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 synthesis of a biocompatible silver nanoparticle derived tripeptide supramolecular hydrogel for antibacterial wound dressings
(2016)
Simon, Turibius
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Wu, Chung-Shu
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Liang, Jie-Chuan
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Cheng, Chieh
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Ko, Fu-Hsiang
Realizing the widespread demand for biocompatible supramolecular hydrogel based wound dressings, we have developed an N-terminally 2(naphthalen-6-yl) acetic acid (Nap) protected Phe-Phe-Cys peptide (Nap-FFC) using a liquid phase method. This Nap-FFC peptide was used to design a supramolecular hydrogel via a self-assembling process. The Nap-FFC short peptides produced stable and transparent silver nanoparticle-based hydrogels (AgNPs@Nap-FFC) wherein the self-assembled Nap-FFC nanofibers acted as scaffolds for the mineralization of silver nanoparticles (AgNPs) and stabilizers of the synthesized AgNPs. The resultant AgNPs@Nap-FFC nanocomposites were characterized using ultraviolet-visible spectrophotometry (UV-vis spectroscopy), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX) studies. The AgNPs@Nap-FFC nanocomposites showed excellent monodispersity, long term stability, and functional flexibility in comparison to other AgNP based nanocomposites. Furthermore, AgNPs@Nap-FFC exhibited strong inhibition against both Gram-positive (methicillin-resistant Staphylococcus aureus) and Gram-negative (Acinetobacter baumannii) bacteria and, most importantly, they showed favorable biocompatibility towards human cervical carcinoma cells (HeLa cells). Hence, this study implies that AgNPs@Nap-FFC nanocomposites can easily be prepared in a cost-effective manner and can be used effectively for future antibacterial wound dressings.
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
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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.
New Synthesis Route of Hydrogel through A Bioinspired Supramolecular Approach: Gelation, Binding Interaction, and in Vitro Dressing
(2015-09-02)
Cheng, Chieh
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Tang, Meng-Che
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Wu, Chung-Shu
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Simon, Turibius
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Ko, Fu-Hsiang
Peptide-based supramolecular hydrogels have been comprehensively investigated in biomaterial applications because of their unique bioactivity, biofunctionality, and biocompatible features. However, the presence of organic building blocks in peptide-based hydrogels often results in low mechanical stability. To expand their practical use and range of applications, it is necessary to develop the tool kit available to prepare bioinspired, peptide-based supramolecular hydrogels with improved mechanical stability. In this paper, we present an innovative electrostatic and cross-linking approach in which naphthyl-Phe-Phe-Cys (NapFFC) oligopeptides are combined with gold nanoparticles (AuNPs) and calcium ions (Ca2+) to produce peptide-based supramolecular hydrogels. We further investigate the interactions among NapFFC, AuNPs and Ca" by microscopy. The morphology of the nanofibrous network constructions and the binding forces exhibited from the hydrogel demonstrated that the combination of two mechanisms successfully enhanced the mechanical stability through the formation of a densely entangled fibrous network of peptide multimers that is attributed to the AuNP linkage and Ca2+-induced agglomeration. UV vis spectrophotometry and fluorescence analysis were also used to demonstrate the enhanced stability of the hydrogel under various conditions such as thermal, solvent erosion, pH value and sonication. All results indicate that the presence of AuNPs and Ca2+ can strengthen the prepared hydrogel by more than doubling the diameter of NapFFC nanofibers, enabling the formation of stronger frameworks and slowing the release of components. Further experiments confirmed that HeLa cells can grow on the bioinspired NapFFC-AuNP hydrogel and exhibit high cell viability and that these cells were killed on contact with a hydrogel containing a drug. Our peptide-based supramolecular hydrogels prepared from the observed electrostatic and cross-linking mechanisn exhibited a significantly improved mechanical stability, making them well suited to use as a drug carrier in hydrogel dressings and as extracellular materials (ECMs) for tissue engineering.
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.
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
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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.