Analytical Chemistry Chemical Cytometry Quantitates Superoxide

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Figure 3. Electropherograms obtained using a PDDA-AuNP coated capillary with the BDD electrode for the study of (A) buffer concentration effect: 25, 50, 75, and 100 mM H3PO4-Tris, pH 3, (B) injection time effect (3, 5, 7, and 10 s), (C) effect of detection potential (+0.6, +0.8, +1.0,+ and 1.2 V vs Ag/AgCl, 3 M NaCl), (D) effect of separation voltage (-5, -10, -15, and -20 kV). The sample mixture consisted of 20 µM IXS, 25 µM (each) VMA, HVA, TRP, 100 µM ISP, 100 µM NMN, 100 µM EP, 50 µM 5-HT, 125 µM HMBA, 125 µM DHBA, and 75 µM TA. homogeneous layer. 28 The incorporation of AuNPs in the polymer network could be attributed to the structural change in pristine PDDA after the synthesis of AuNPs. It has been shown that CdC and C-N are produced after PDDA reacts with HAuCl4 by (28) Zhang, Z.-X.; Yan, B.; Liu, K.; Liao, Y.-P.; Liu, H.-W. Electrophoresis 2009, 30, 379–387. 6900 Analytical Chemistry, Vol. 82, No. 16, August 15, 2010 comparing the FTIR spectra of PDDA and PDDA-AuNPs. 13 For the latter, a new peak appears at 1578 cm -1 , which can be assigned for CdC and CdN in-plane vibration. In aqueous milieu, gold nanoparticles are negatively charged and the absolute value of the �-potential decreases as the pH decreases, whereas above pH 5.8, the absolute value of the �-potential
Table 2. Linearity and Detection Limit of the Analytes a,b analytes linear range (µM) calibration equation R2 detection limit (µM) indoxyl sulfate (IXS) 1.00-40 I ) 0.4839X+0.1490 0.9998 0.3 vanillylmandelic acid (VMA) 1.25-50 I ) 0.3635X+0.3036 0.9998 0.4 homovanillic acid (HVA) 1.25-50 I ) 0.3034X+0.5667 0.9998 0.4 tryptophan (TRP) 1.25-50 I ) 0.3025X+1.0870 0.9998 0.4 isoproterenol (ISP) 5.00-200 I ) 0.0871X+0.7481 0.9995 1.7 normetanephrine (NMN) 5.00-200 I ) 0.0865X+0.6429 0.9995 1.7 epinephrine (EP) 5.00-200 I ) 0.0945X+0.3850 0.9995 1.7 5-hydroxytryptamine (5-HT) 2.50-100 I ) 0.1686X+0.9364 0.9995 0.8 4-hydroxy-3-methoxybenzylamine (HMBA) 6.25-250 I ) 0.0822X+0.0446 0.9991 2.1 3,4- dihydroxybenzylamine (DHBA) 6.25-250 I ) 0.0866X+0.3842 0.9991 2.1 tryptamine (TA) 3.75-150 I ) 0.1476X+0.5307 0.9995 1.3 a I ) peak current (nA), X ) analyte concentration (µM). b Electrophoretic separation was carried out using a PDDA-AuNP coated capillary (50 µm id, 365 µm od) with an effective length of 45 cm, running buffer, 50 mM H3PO4-Tris, pH 3.0, separation voltage, -10 kV, injection for 5s at -10 kV. Detection: BDD electrode at +1.0 V vs. Ag/AgCl, 3M NaCl. Figure 4. The comparison electropherograms for (a) nonsample stacking using a running buffer of 50 mM H3PO4-Tris, pH 4 with an injection time of 5 s (b) sample stacking, injection buffer: 10 mM H3PO4-Tris, pH 2, and the running buffer of 50 mM H3PO4-Tris, pH 4 with an injection time of 10 s. (c) sample stacking, injection buffer: 10 mM H3PO4-Tris, pH 2, and the running buffer was similar to the injection buffer with an injection time of 10 s. Concentration of analytes: 50 µM (each) IXS, VMA, AA, HVA, UA, TRP. Separation voltage: -10 kV. BDD at +1.0 V vs Ag/AgCl, 3 M NaCl. becomes almost constant (∼-45 to -50 mV). The negative charge of the gold surface may be explained by the fact that the Au-OH present on the gold surface can lose protons as the pH increases to form Au-O-groups on the nanoparticle surface. 29 AuNPs have a partially hydroxylated surface with a pKa value of 3.2 (Au-OH) in the presence of water. 29 At pH 3, around the pKa value of AuNPs, -OH groups are predominant (-OH groups/O - groups ) 1.6). The rest of the gold surface should be metallic, i.e., essentially hydrophobic. Therefore, AuNPs would display ionic and hydrophobic interaction, as well as hydrogen bonding with the PDDA network. The synthesis and incorporation of AuNPs in the polymer network would affect the PDDA structural change, which in turn increased the charge density and coverage efficiency of the coating. At pH4or5,Au-O - groups were predominant, resulting in a (29) Sylvestre, J.-P.; Kabashin, A. V.; Sacher, E.; Meunier, M.; Luong, J. H. T. J. Am. Chem. Soc. 2004, 126, 7176–7177. decrease of the �-potential of the PDDA-AuNPs composite, i.e., the EOF is reduced. Notice that TRP also becomes more neutral at pH 5, whereas the charges of the catechoamines and indolamines were highly negative and such analytes were expected to interact strongly with PDDA. Indeed, all catecholamines and indoleamines were not eluted after 24 min into the experiment. In contrast, Zhang et al. 28 reported that the separation using the PDDA coated capillary is significantly longer than the one modified with PDDA-AuNPs for analysis of heroin and impurities. In such a study, the separation is performed at pH 5.2 with addition of 3% methanol into the running buffer consisting of 120 mM ammonium acetate. Therefore, it was somewhat difficult to compare the result obtained in this work with that of Zhang et al. 28 Other Optimal Conditions and Sample Stacking. The 50 mM phosphoric-Tris buffer pH 3 appeared to provide the highest detection sensitivity with good separation resolution. Indeed, 4-hydroxy-3-methoxybenzylamine comigrated with 3,4-dihydroxybenzylamine when the buffer strength increased to 100 mM and the run was longer with lower detection sensitivity (Figure 3A). This pair was coeluted as one single peak if the separation was carried out with the PDDA coated capillary. Thus, a running buffer consisting of 50 mM phosphoric-Tris, pH 3 was used to optimize the separation potential and the detection potential of the BDD electrode. With respect also to detection sensitivity and separation efficiency (N/cm), the electrokinetic injection of the sample at -10 kV for 5 s was optimal compared to the results obtained at shorter (3 s) or longer (7 and 10 s) injection times (Figure 3B). Beyond 5 s, the resulting peaks were very broad with compromised detection sensitivity and separation efficiency. In contrast, 3 s was not sufficient, as reflected by considerably lower peaks. The BDD detection potential, poised at +1 V vs 3 M Ag/AgCl provided highest detection sensitivity compared to the detection performed at lower or higher applied potentials (Figure 3C). Both resolution and detection sensitivity were severely deteriorated when the separation was conducted at -15 kV and -20 kV, compared to the run at -10 kV (Figure 3D). Linearity and LOD obtained for 11 analytes are summarized in Table 2. The four fast migrating analytes, IXS, VMA, HVA, and tryptophan exhibited a LOD of 0.3 µM, whereas a higher LOD, ∼1 µM was obtained for the slower migrating group. Analytical Chemistry, Vol. 82, No. 16, August 15, 2010 6901
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Anal. Chem. 2010, 82, 6745-6750 Let
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purchased from Invitrogen-Molecular
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Figure 3. Electropherograms of TPP-
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Anal. Chem. 2010, 82, 6751-6755 Res
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(pH 8.0) with cysteine and cystamin
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Figure 4. Ion mobility mass spectra
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GOx glucose + O298 gluconic acid +
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coater at 2000 rpm for 20 s, and th
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Figure 5. Comparison of cyclic volt
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in channels with either no grooves
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indicators of atmospheric processin
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Figure 1. GC/MS total ion chromatog
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Table 2. Concentrations and Stable
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on a substrate are preferred. 20-24
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Figure 4. SERS analysis of NAADP co
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Anal. Chem. 2010, 82, 6775-6781 Hig
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tion, 2 µL of proprionaldehyde wer
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Figure 4. Analysis of 2a by HPLC-MS
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eaction of 1a with PBH can be condu
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Numerous references had demonstrate
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Figure 1. TEM images of the prepare
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Figure 4. Schematic representation
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esult in a big SPR signal change wi
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also reduces chemical noise, which
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Table 1. Extraction Yields, Liquid
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scanning of AMPP amides of the anal
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Anal. Chem. 2010, 82, 6797-6806 δ
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Figure 1. Schematic view of the pre
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from the specimen and enclosed in a
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Figure 4. (A) IRMS mass-44 chromato
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Table 3. Ambient Measurement Result
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Anal. Chem. 2010, 82, 6807-6813 Dir
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Polymerase (1 U per sample). Reacti
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of which was constant for all ampli
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analytically useful signals at less
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carbon black and RP-C18 for the ext
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solution in an equal volume, and 1
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Table 2. Concentrations and Ratios
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Anal. Chem. 2010, 82, 6821-6829 Mac
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mg/mL protein, followed by separati
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Figure 2. Productivity of SEQUST an
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Figure 4. High-resolution MS/MS spe
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Figure 6. Characterization of PSMs
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containing T-T mismatches. 23 Based
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Figure 1. Extinction spectra of sol
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Figure 3. (A) The value of Ex650 nm
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Figure 5. Extinction spectra and co
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wished to explore the dehydration o
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constant medium for separation; we
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Figure 2. Standards of (Pi)n, n ) 1
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Figure 5. Quantitative calibration
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Anal. Chem. 2010, 82, 6847-6853 Met
Page 105 and 106: Figure 1. 226 Ra spectrum by liquid
Page 107 and 108: Table 1. Counting Properties and De
Page 109 and 110: Table 3. Analysis of 226 Ra in Sedi
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Page 113 and 114: Figure 2. Optical transmission meas
Page 115 and 116: Figure 5. Volcano plots detailing t
Page 117 and 118: data as well. The 41 genes in Table
Page 119 and 120: corresponding compound if its chemi
Page 121 and 122: Figure 1. Schematic illustration of
Page 123 and 124: Table 1. Absolute Quantification Re
Page 125 and 126: ment. Therefore, the long-time drea
Page 127 and 128: Figure 1. Chemically actuated micro
Page 129 and 130: Figure 2. Influence of a surfactant
Page 131 and 132: Figure 5. Device to eject and mix s
Page 133 and 134: Anal. Chem. 2010, 82, 6877-6886 Imm
Page 135 and 136: NaCl, phosphate buffer saline (PBS)
Page 137 and 138: Figure 2. Product ion mass spectra
Page 139 and 140: -70 °C resolved the problem, givin
Page 141 and 142: Table 1. Intraday Precision and Acc
Page 143 and 144: Anal. Chem. 2010, 82, 6887-6894 Fer
Page 145 and 146: Figure 1. Infrared spectra of (A) u
Page 147 and 148: Figure 3. Cyclic voltammograms obta
Page 149 and 150: Figure 6. Calculated charge from ch
Page 151 and 152: Anal. Chem. 2010, 82, 6895-6903 Ele
Page 153 and 154: Table 1. Chemical Structure, pKa Va
Page 155: pH with a tilted baseline (Figure 1
Page 159 and 160: ascorbic acid (AA), uric acid (UA),
Page 161 and 162: the multielement capabilities, the
Page 163 and 164: RESULTS AND DISCUSSION Sulfur Detec
Page 165 and 166: Table 2. Molecular Properties and C
Page 167 and 168: Anal. Chem. 2010, 82, 6911-6918 Dir
Page 169 and 170: dilution and hybridization buffer.
Page 171 and 172: solution under appropriate incubati
Page 173 and 174: Figure 4. Standardization curve for
Page 175 and 176: Anal. Chem. 2010, 82, 6919-6925 Ele
Page 177 and 178: the ×10 objective, to have a large
Page 179 and 180: Figure 2. With a suitable removal o
Page 181 and 182: the NB signal in a much better foot
Page 183 and 184: Scheme 1. Reactions of Selenium Rea
Page 185 and 186: Figure 2. (a) ESI-MS spectrum showi
Page 187 and 188: Figure 4. (a) ESI-MS spectrum showi
Page 189 and 190: Anal. Chem. 2010, 82, 6933-6939 Dif
Page 191 and 192: trode 28 by a finite element using
Page 193 and 194: Figure 4. Comparison between simula
Page 195 and 196: Figure 6. Comparison between simula
Page 197 and 198: educed in the vicinity of double bo
Page 199 and 200: Figure 2. Normalized product ion ab
Page 201 and 202: Figure 4. EID (a) and IRMPD (b) of
Page 203 and 204: Anal. Chem. 2010, 82, 6947-6957 Ide
Page 205 and 206: Figure 1. Schematic flowchart showi
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difference, ppm compound Table 1. I
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isoforms, its successful use, in th
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Figure 5. Extracted ion current ESI
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m/z 1172.935 was observed for Ser14
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linked products via affinity tags.
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Scheme 2. Fragmentation Mechanism o
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Figure 1. (A) ESI-LTQ-CID-MS 2 prod
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Figure 3. (A) ESI-LTQ-CID-MS 2 prod
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Figure 5. (A) MALDI-TOF/TOF product
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Anal. Chem. 2010, 82, 6969-6975 Ana
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Figure 3. Equilibrium response as a
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Figure 6. The average measured resp
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for the fill time, and we find that
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nucleotide tails. 3-5 Thus, the amo
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allow the use of higher aptamer con
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quent ligation of the aptamers afte
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Anal. Chem. 2010, 82, 6983-6990 Imp
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Figure 2. Configuration editor wind
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Figure 4. Dependencies between volu
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Since the time for liquid expulsion
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Anal. Chem. 2010, 82, 6991-6999 Int
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Figure 1. Representation of the Car
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Table 2. Capillary Electrophoresis
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Figure 4. (A) Typical raw electroph
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field. DNA profiles were delivered
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Another approach to handle this lim
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(principal components, PCs) in whic
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Figure 5. Relevant score plots and
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CONCLUSIONS In this paper we have i
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electroactive-species loaded liposo
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Figure 2. Qdot-based FLFTS response
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Figure 6. Fluorescence imaging of Q
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Anal. Chem. 2010, 82, 7015-7020 Sel
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Table 1. Effect of 1 D-LC Condition
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Figure 3. Peak-production rate vers
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Anal. Chem. 2010, 82, 7021-7026 Cel
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luciferase (T7 control vector) was
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Figure 3. Inhibitory effects of luc
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Anal. Chem. 2010, 82, 7027-7034 Pat
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Electrochemistry. Electrochemical m
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Figure 2. SEM images of Au substrat
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Table 3. Film Thickness Measurement
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Anal. Chem. 2010, 82, 7035-7043 Qua
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Figure 1. (A) FL spectra of BSPOTPE
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Figure 4. (A) Variation in the FL i
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Figure 6. (A) FL spectra of BSPOTPE
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Scheme 1. Proposed Mechanism for Fl
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one or more drawbacks including poo
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Figure 2. Free fluorophores do not
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Anal. Chem. 2010, 82, 7049-7052 Dev
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Figure 2. Comparative analysis of d
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Analytical Chemistry Chemical Cytometry Quantitates Superoxide

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