Ionization of Submicron-Sized Particles by Laser-Induced RF Plasma

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Ionization of Submicron-Sized Particles by LaserInduced RF Plasma for Mass Spectrometric Analysis Shao-Yu Liang, Avinash A. Patil, Chou-Hsun Han, Szu-Wei Chou, Wen Chang, Po-Chi Soo, Huan-Cheng Chang, and Wen-Ping Peng Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.8b03983 • Publication Date (Web): 24 Oct 2018 Downloaded from http://pubs.acs.org on October 27, 2018

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Analytical Chemistry

Ionization of Submicron-Sized Particles by Laser-Induced RF Plasma for Mass Spectrometric Analysis Shao-Yu Liang1, Avinash A. Patil1, Chou-Hsun, Han1, Szu-Wei Chou1,5, Wen Chang3, Po-Chi Soo4, Huan-Cheng Chang2, Wen-Ping Peng*,1 1

Department of Physics, National Dong Hwa University, Shoufeng, Hualien, Taiwan

97401 2

Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan 10617

3

Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529

4

Department of Laboratory Medicine and Biotechnology, Tzu Chi University,

Hualien, Taiwan 97004 5

AcroMass technologies Inc., Hukou, Hsinchu, Taiwan 30352

* To whom correspondence should be addressed, e-mail: [email protected]

ACS Paragon Plus Environment

Analytical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ABSTRACT A laser-induced RF plasma (LIRFP) ion source was developed to ionize submicronmeter sized particles for the first time. The LIRFP ion source can increase the charge of those particles to several thousand charges via charge exchange reactions so that those particles can be trapped and analyzed with charge detection quadrupole ion trap mass spectrometer (CD QIT-MS). Different reagent gases for charge exchange reaction were investigated, viz. argon, nitrogen, oxygen, methane, helium, krypton, xenon, argon/methane (with ratio of 10:1 and 2:1), argon/nitrogen (with ratio of 1:1), nitrogen/oxygen (10:1), krypton/methane (10:1) and air. The average charge of 0.75 m polystyrene particles could reach 1631 using argon/methane mixture with a ratio of ~ 10:1. The average charges for freeze-dried Escherichia coli EC11303, Escherichia coli strain W and Staphylococcus aureus were 842, 1112 and 971, respectively, with mass-to-charge ratio (m/z) range from 107 to 108; and the average masses were 3.5×1010 Da, 6.0×1010 Da and 5.6×1010 Da, respectively. The average mass and charge of the vaccinia virus were ~ 9.1×109 Da and ~ 708 with a m/z of ~ 107. This LIRFP CD QIT-MS method was rapid with only 20 minutes for each sample measurement.


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Keywords: Laser-induced RF plasma; charge exchange reaction; polystyrene, bacterial, and viral particles; charge detection quadrupole ion trap mass spectrometer



INTRODUCTION Electrospray ionization (ESI)1 and matrix-assisted laser desorption/ionization (MALDI)2, 3 are major techniques to produce protein and protein complex ions, e.g. viruses (from 20 nm to 300 nm)4-8. With ESI ion source, a quadrupole time-of-flight mass spectrometer can measure bacteriophage HK97 capsids which have mass of 18 MDa9 (size ~ 50 nm) and charge of ~ 35010, 11 while a charge detection mass spectrometer can detect bacteriophage P22 procapsids9 with mass of ~ 23.6 MDa and charge of ~ 450 and tobacco mosaic virus12 with mass of ~ 40 MDa and charge of ~ 300 to 1000. With MALDI ion source, the mega-Dalton sized nanoparticles can be detected and characterized with superconducting tunnel junction cryodetection mass spectrometry.13-15 To measure micron-meter sized particles such as cancer cells16-18, red blood cells19, 20, silica and polystyrene particles21, 22 with sizes > 3 m (~ 1013 Da with charge of ~ 3000) laser-induced acoustic desorption (LIAD) ion source16, 19, 21, 23, the ambient aerodynamic desorption/ionization ion source24 and ESI ion source18 were developed and coupled with the charge detection quadrupole ion trap mass spectrometer (CD QIT-MS) for mass detection. To further measure smaller mass of bioparticles, e.g. bacteria and viruses (~ 110851010 Da with charge of < 200) between 80 nm and several m in size, single particle mass measurement25, 26 was


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developed by using LIAD ion source coupled with the QIT-MS23 or with cylindrical ion trap-MS27. To streamline the mass measurement of submicron-meter sized particles with CD QIT-MS, we developed a new ion source, laser-induced RF plasma (LIRFP), to increase charges of submicron-meter sized particles to a few thousand so that each mass spectrum of those submicron-meter sized particles could be detected by CD QIT-MS within a few seconds. A pulsed laser was used to trigger a radio frequency (RF) field to produce plasma which interacted with different reagent gases, e.g. argon, nitrogen, air, argon/methane (10:1), and argon/nitrogen (1:1) to form ions. Then the analytes interacted with those ions to gain positive charges. With this new LIRFP ion source, the CD QIT-MS could acquire ion signals with good signal-to-noise ratio and measure the mass-to-charge (m/z) ratio and charge (z) of submicron-sized macroions. Therefore, mass spectra, mass and charge distributions of freeze-dried E. coli EC11303, E. coli strain W, S. aureus and vaccinia virus were obtained successfully.

EXPERIMENTAL SECTION LIRFP ion source The LIRFP ion source involves two processes: desorption and ionization. First, biological samples (analytes) were desorbed using a high-energy pulsed laser that was



beamed from the backside of the sample substrate to generate acoustic waves (Figure 1b on the left side). The advantages of using acoustic waves for the desorption of viruses and cells include no matrix interference23, no fragmentation of analytes, and a reduction of background interference.28, 29 Second, a RF plasma was triggered by the same laser pulse to create a plasma cloud that was maintained for a few seconds to ionize analytes by ion/molecule reactions with Ar ions (can be N2 or other reagent gases) that were generated by the addition of argon reagent gas. The reagent molecular ions, Ar+, were present in the plasma and the ionic charge was transferred to the particles via charge transfer ionization (M + Ar+ → M+ + Ar) although other reactions could not be excluded. The LIRFP ion source employed a function generator to input a sine wave to a power amplifier which could boost a toroidal transformer to a voltage of 1 kVp-p (Vp-p is the peak-to-peak amplitude) with a frequency of 133 kHz and other frequency settings. The 532 nm pulsed Nd:YAG laser triggered the production of plasma. The laser duration was 7 ns, and the power density on the Si wafer ranged from 1 to 5×1010 W/cm2 (with a spot size diameter of ~ 100 m). Electrons and negative ions (e.g., e-, H-, H2-) were generated by a pulsed Nd:YAG laser30, which could induce plasma using a RF source operating at 133 kHz. The plasma then interacted with argon or argon-methane reagent gas to form ions31, 32; e.g., Ar+, ArH+, CH3+, CH4+ etc.


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When the particles were desorbed by acoustic waves and then passed through the plasma region, they would interact with the argon ions and acquire positive charges (Figure 1b on the center side). CD QIT-MS setup The experimental setup was comprised of a quadrupole ion trap that was operated in the audio frequency region (from several hundred Hz to few kHz) to analyze charged particles with masses ranging from 109 to 1013 Da (Figure 1). The biological samples of interest were first loaded onto a gold-coated silicon wafer (0.5mm thickness, Sigma-Aldrich (St. Louis, MO, USA)) without any organic matrix or salt. The gold-coated silicon wafer was connected to a ground potential and a RF field was created by a looped metal wire. The 532 nm pulsed Nd:YAG laser beam impinged on the backside of the sample substrate to desorb the particles, which entered the ion trap through the gap between the ring and the end-cap electrodes. Then the plasma was created within this region, as shown in the inset of Figure 1a. A hole was drilled in the end cap to enable charge detection. Trapping of the particles from the laser desorption was achieved using a 1600–14000 Hz AC field, depending on the particle sizes, with an amplitude of 800 Vp-p. Approximately 60 mTorr of helium buffer gas was used for ion cooling and trapping. To generate the plasma, the pressure of argon, nitrogen, argon/methane mixture, etc. was set to 1.4 kg/cm2 (20 psi) and was



controlled by a pulse generator (General Valve Multichannel IOTA ONE) with ontime and off-time settings of 269 s and 400 ms, respectively.

RESULTS AND DISCUSSION Conditions of the LIRFP ion source Conditions of the LIRFP ion source, such as reagent gas species, gas pressure, plasma RF frequency and RF voltage, could affect the charge number of particles. Table S1 shows the experimental parameters used to test the plasma conditions. Reagent gases such as argon, nitrogen, oxygen, methane, helium, krypton, xenon, argon/methane (with ratio of 10:1 and 2:1), argon/nitrogen (1:1), nitrogen/oxygen (10:1), krypton/methane (10:1) and air were used to obtain the ion signals of 0.75 m polystyrene particles. It was found that helium, krypton, krypton/methane (10:1), and xenon reagent gases could not produce ion signals while argon, nitrogen, argon/methane (10:1), argon/nitrogen (1:1), and air could produce good ion signals. Figure 2 compares the charge number of particles using these five reagent gases. In Figure 2a, the charge histogram of 0.75 m polystyrene particles with argon reagent gas shows that an average charge number was 837. In Figure 2b, we found the average charge of 0.75 m polystyrene particles could be further enhanced by mixing argon with methane with a ratio of Ar:CH4=10:1. The average charge generated by an


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argon/methane mixture was increased to 1631, approximately a factor of two higher than the average charge created by argon reagent gas. The increase in charge number might be attributed to the increase in charge exchange reaction rate, which was certified by Field et al. that an argon/methane mixture at pressure of a few mTorr to 60 mTorr could increase the charge exchange reaction rate by approximately two orders of magnitude.31 However, with pure methane gas no detectable ion signals (Table S1) were observed. To explore the effect of the argon/methane mixture, the ratio of 2:1 was conducted and poor ion signals were found. Therefore, we concluded that in order to get more charge number, it was necessary to lower the ratio of methane gas. Figure 2c shows the average charge of 0.75 m polystyrene particles was 711 with nitrogen reagent gas. The major components of air are ~78.08 vol% nitrogen, ~20.95 vol% oxygen and ~0.93 vol% argon, which inspired us to test air as a reagent gas. Figure 2d shows the average charge of 0.75 m polystyrene particles using air plasma was 618 which was less than that with pure N2 gas. To understand why the charge number dropped while using air plasma, we test another major component of air, O2, as a reagent gas and found no ion signal could be obtained (Table S1). To understand the ratio of these three components of air influencing charge number, we first tested the nitrogen/oxygen mixture and found no ion signals until the ratio



reached 10:1 in which the signals were low. This indicated that oxygen gas might suppress the charge exchange reaction of the nitrogen/oxygen mixture. Then, we mixed nitrogen and argon with a ratio of 1:1, and good ion signals were observed (Table S1). Figure 2e shows the average charge number of Ar/N2 mixture was 798 higher than the charge number of pure nitrogen gas (711), indicating the argon gas prompted the charge exchange reaction. This observation was also supported by Bogaerts who developed a numerical model for a glow discharge in Ar/N2 mixture and found the order of the produced ion number density was 𝐴𝑟 + ≫ 𝑁2+ > 𝑁 + ≫ 𝑁4+ ≫ 𝑁3+ .33 The increase in charge number obtained with Ar/N2 mixture indicated the abundant Ar+ ions involved in the charge exchange reaction. So the charge number generated by air plasma was depleted by oxygen but increased by argon. The charge number generated by air plasma (618) was lower than that by pure nitrogen gas (711) and that by pure argon gas (837) because of its component of oxygen. The plasma generation was tested with rf frequency from 26 kHz to 927 kHz (Table S1). The best rf frequency to generate plasma and obtain good ion signals was from 133 kHz to 182 kHz with reagent gases including argon, nitrogen, argon/methane (10:1), and argon/nitrogen (1:1). With air, the best rf frequency was from 133 kHz to 168 kHz. It was observed the best amplitude of plasma voltage was from 1 kVp-p to 1.3 kVp-p. If the amplitude of rf voltage was set below 1 kVp-p, the


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plasma was too diffuse and hard to create charge. If the voltage was set above 1.3 kVp-p, the plasma was localized and confined near the wire, and the ionization efficiency became low. The plasma generation by LIRFP ion source is different from that by corona discharge which ionize particles after using LIAD to desorb particles21. The LIRFP is controlled by an external RF source while corona discharge occurs inside the ion trap. With corona discharge, the plasma produced inside the ion trap would interfere with the ion trap field and made the ion trajectory unstable. Therefore, the use of LIRFP ion source can minimize particle lost during the ion trapping of particles. Moreover, the LIRFP can increase the charge number of submicron-meter particles, but with corona discharge16, 19, 21 it is very challenging to increase the charge of smaller sized particles (< 3 m). Why LIRFP could increase the charge number, but corona discharge could not? The ion trap was filled with helium buffer gas to cool down ions. According to Table S1, if we adopt the helium gas as reagent gas, no signals can be observed. This explains why the corona discharge inside the trap could not increase the particle charges. Another factor is the plasma frequency of LIRFP ion source. With LIRFP, we found good ion signals could be obtained using plasma frequency of 13050 kHz (Table S1), this plasma frequency range is much higher than the rf frequency applied to the ion trap (~ few kHz). Therefore, corona discharge could not



get ion signals for submicron-meter sized particles. Mass spectra, mass and charge distributions of submicron-meter sized particles Mass spectra of submicron-meter sized particles, such as polystyrene particles, bacterial cells, and viruses, were acquired by LIRFP CD QIT-MS are shown in Figure S4 and Figure 3. The m/z range was from 107 to 1010 with particle sizes from 0.3 m to 2 m, and generally 10 to 20 m/z peaks were observed in the mass spectra. The bacterial and viral samples produced more peaks than polystyrene particles did, and the charge number on each particle was approximately a few thousand. Mass and charge distributions for polystyrene with sizes of 0.3, 0.4, 0.5, 0.75 and 2 m are shown in Figure S5a-e. The measured masses were (7.02.5)109, (1.80.7)1010, (3.91.8)1010, (1.30.7)1011 and (2.10.9)1012, respectively, which are in good agreement with the calculated masses of (6.50.3)109, (2.10.1)1010, (4.10.1)1010, (1.40.7)1011 and (2.10.2)1012 Da, respectively. Charge distributions for different particle sizes are also shown in Figure S5f-j. The average charge on particles decreased from ~1600 to ~600 as the particle sizes decreased from 0.75 m to 300 nm. The polystyrene particle size standards were measured by LIRFP CD QIT-MS and the ion trap was calibrated as the procedures in our previous work34 and in the supporting information. In addition to the measurement of polystyrene microparticles, we also applied


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LIRFP CD QIT-MS to measure the mass and charge distributions of various types of intact bacterial cells and viruses. Masses and mass distributions of freeze-dried E. coli EC11303, E. coli strain W and S. aureus were measured (3.5±1.4)×1010 Da, (6.0±2.5) ×1010 Da and (5.6±2.0)×1010 Da, respectively and are shown in Figure 4. Not only bacterial particles but also viruses could be desorbed and ionized with an LIRFP ion source. The m/z range of vaccinia viruses was measured to be approximately 107 as shown in Figure 3d, and the measured mass and average charge were (9.1±3.5)×109 Da and 708, respectively (Figure 4d and Figure 4h). Comparison of the bacterial particle mass measurements using LIRFP CD QITMS and optical microscope To verify the accuracy of our measured bacterial masses, we employed confocal microscopy to measure the sizes of bacteria, and their masses were calculated based on a reported density of 1.16 g/cm3 for dead cells35, as shown in Table S2. The measured masses of Staphylococcus aureus, E. coli EC11303 and E. coli strain W by optical microscopy were (1.3±0.4)×1011, (1.3±0.7)×1011 and (2.0±0.6)×1011 Da, respectively. The results show the mass measured by optical microscopy were wet mass with water inside the cells, and thus was greater than the dry mass obtained under vacuum conditions. Thus, the dehydration (i.e., water percentage) of Staphylococcus aureus, E. coli EC11303 and E. coli strain W were calculated as 57%,



73% and 70%, respectively, which is consistent with the reported value of 70% for E. coli cells.36 We observed that the size of E. coli EC11303 was smaller than that of E. coli strain W (Table S3), so the mass of E. coli EC11303 was also smaller than that of E. coli strain W, which is in agreement with the findings of our mass spectrometric measurements. The results of our measurement were also consistent with the reported mass of E. coli (110±30 fg, ~ (6.6±1.8)×1010 Da) measured by nanomechanical resonators.37 Furthermore, we measured the mass of vaccinia virus and found its mass (9.1±3.5)×109 Da (~ 15.1±5.7 fg) was close to the mass of 7.912.4 fg measured by micron-scale cantilever beams38, 39, indicating that the desorbed viral and bacterial particles were intact during the LIRFP desorption/ionization process. The coefficient of variation (CV, the ratio of standard deviation to the mean) for the mass distributions of three bacteria was approximately 40%, which was consistent with those measured by microscopy if dehydration was taken into consideration, indicating that our measurement reflects true bacterial mass and mass distribution.

CONCLUSION We developed an LIRFP ion source to increase the charge of submicron-sized particles. The LIRFP ion source can generate good ion signals with argon, nitrogen, argon/methane (10:1), argon/nitrogen (1:1), and air reagent gases. The most effective


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mixture of argon and methane was a ratio of ~10:1. The masses and mass distributions of polystyrene particles, bacteria and viruses were found to be in good agreement with those of other studies. Our method could be applied to extend the detection mass range of native mass spectrometry40, 41, detect fine and ultrafine particles (from 0.12.5 m) in ambient air42-46 and acquire the tandem mass of large viruses and bacterial samples using miniature ion trap mass spectrometers.47 Besides, air plasma could be used in a portable ion trap mass spectrometer without using a gas cylinder .

ASSOCIATED CONTENT The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.analchem. Mass calibration procedure of a LIRFP CD QIT-MS, design of the looped metal wire, gas flow conditions, charge detector and noise reduction, ion trapping conditions, correlation of charge number and ion trapping conditions, different reagent gases for LIRFP plasma conditions (Table S1), comparison with other viral particle mass measurements, and comparison of the charge number obtained by ESI, LIAD, MALDI and LIRFP ion sources (Table S4).

ACKNOWLEDGMENT



The present study was supported by grants with contract numbers MOST 105-2112M-259-002-MY3 (WPP) from the Ministry of Science and Technology Taiwan. The authors thank Miss Huei-Yin Cheng and Mr. Cheng-Han Yang for the preparation of vaccinia virus samples, Mr. Ming-An Wu for drawing setup figures and AcroMass technologies Inc. for technical support. Suggestions from Prof. R. G. Cooks were appreciated.


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REFERENCES (1) Fenn, J.; Mann, M.; Meng, C.; Wong, S.; Whitehouse, C. Electrospray ionization for mass spectrometry of large biomolecules. Science 1989, 246, 64-71. (2) Tanaka, K.; Waki, H.; Ido, Y.; Akita, S.; Yoshida, Y.; Yoshida, T.; Matsuo, T. Protein and polymer analyses up to m/z 100 000 by laser ionization time-offlight mass spectrometry. Rapid Commun. Mass Spectrom. 1988, 2, 151-153. (3) Karas, M.; Hillenkamp, F. Laser desorption ionization of proteins with molecular masses exceeding 10,000 daltons. Anal.Chem. 1988, 60, 22992301. (4) Fuerstenau, S. D.; Benner, W. H.; Thomas, J. J.; Brugidou, C.; Bothner, B.; Siuzdak, G. Mass spectrometry of an intact virus . Angew. Chem. Int. Ed. 2001, 40, 542-544. (5) Pierson, E. E.; Keifer, D. Z.; Selzer, L.; Lee, L. S.; Contino, N. C.; Wang, J. C. Y.; Zlotnick, A.; Jarrold, M. F. Detection of Late Intermediates in Virus Capsid Assembly by Charge Detection Mass Spectrometry. J. Am. Chem. Soc. 2014, 136, 3536-3541. (6) Tito, M. A.; Tars, K.; Valegard, K.; Hajdu, J.; Robinson, C. V. Electrospray Timeof-Flight Mass Spectrometry of the Intact MS2 Virus Capsid. J. Am. Chem. Soc. 2000, 122, 3550-3551. (7) Uetrecht, C.; Versluis, C.; Watts, N. R.; Wingfield, P. T.; Steven, A. C.; Heck, A. J. R. Stability and Shape of Hepatitis B Virus Capsids In Vacuo. Angew. Chem. Int. Ed. 2008, 47, 6247-6251. (8) Keifer, D. Z.; Jarrold, M. F. Single-molecule mass spectrometry. Mass Spectrom. Rev. 2017, 36, 715-733. (9) Snijder, J.; Rose, R. J.; Veesler, D.; Johnson, J. E.; Heck, A. J. R. Studying 18 MDa Virus Assemblies with Native Mass Spectrometry. Angew. Chem. Int. Ed. 2013, 52, 4020-4023. (10) Morgner, N.; Robinson, C. V. An Assignment Strategy for Maximizing Information from the Mass Spectra of Heterogeneous Protein Assemblies. Anal. Chem. 2012, 84, 2939-2948. (11) Tseng, Y.-H.; Uetrecht, C.; Yang, S.-C.; Barendregt, A.; Heck, A. J. R.; Peng, W.P. , Game-Theory-Based Search Engine to Automate the Mass Assignment in Complex Native Electrospray Mass Spectra. Anal. Chem. 2013, 85, 1127511283. (12) Fuerstenau, S. D. Whole Virus Mass Analysis by Electrospray Ionization. J. Mass Spectrom. Soc. Jap. 2003, 51, 50-53 (13) Sipe, D. M.; Plath, L. D.; Aksenov, A. A.; Feldman, J. S.; Bier, M. E.



Characterization of Mega-Dalton-Sized Nanoparticles by Superconducting Tunnel Junction Cryodetection Mass Spectrometry. ACS Nano 2018, 12, 2591-2602. (14) Bier, M. E. Cryodetection MS of Polystyrene and Viral Particles. Flexible Package Conf. of the Society of Plastics Engineers 2008, Feb. 24-27th. (15) Wenzel, R. J.; Matter, U.; Schultheis, L.; Zenobi, R. Analysis of Megadalton Ions Using Cryodetection MALDI Time-of-Flight Mass Spectrometry. Anal. Chem. 2005, 77, 4329-4337. (16) Peng, W. P.; Lin, H. C.; Lin, H. H.; Chu, M.; Yu, A. L.; Chang, H. C.; Chen, C. H. Charge-monitoring laser-induced acoustic desorption mass spectrometry for cell and microparticle mass distribution measurement. Angew. Chem. Int. Ed. 2007, 46, 3865-3869. (17) Lin, H. C.; Lin, H. H.; Kao, C. Y.; Yu, A. L.; Peng, W. P.; Chen, C. H. Quantitative Measurement of Nano-/Microparticle Endocytosis by Cell Mass Spectrometry. Angew. Chem. Int. Ed. 2010, 49, 3460-3464. (18) Ozdemir, A.; Lin, J.-L.; Gulfen, M.; Lai, S.-H.; Hsiao, C.-J.; Chen, N. G.; Chen, C.H. ESI MS for Microsized Bioparticles. Anal. Chem. 2017, 89, 13195-13202. (19) Nie, Z.; Cui, F.; Tzeng, Y. K.; Chang, H. C.; Chu, M.; Lin, H. C.; Chen, C. H.; Lin, H. H.; Yu, A. L. High-speed mass analysis of whole erythrocytes by chargedetection quadrupole ion trap mass spectrometry. Anal. Chem. 2007, 79, 7401-7407. (20) Xiong, C.; Zhou, X.; He, Q.; Huang, X.; Wang, J.; Peng, W.-P.; Chang, H.-C.; Nie, Z. Development of Visible-Wavelength MALDI Cell Mass Spectrometry for High-Efficiency Single-Cell Analysis. Anal. Chem. 2016, 88, 11913-11918. (21) Peng, W. P.; Lin, H. C.; Chu, M. L.; Chang, H. C.; Lin, N. H.; Yu, A. L.; Chen, C. H. Charge monitoring cell mass spectrometry. Anal. Chem. 2008, 80, 25242530. (22) Xiong, C.; Zhou, X.; Zhang, N.; Zhan, L.; Chen, S.; Wang, J.; Peng, W.-P.; Chang, H.-C.; Nie, Z. Quantitative Assessment of Protein Adsorption on Microparticles with Particle Mass Spectrometry. Anal. Chem. 2014, 86, 38763881. (23) Peng, W. P.; Yang, Y. C.; Kang, M. W.; Tzeng, Y. K.; Nie, Z. X.; Chang, H. C.; Chang, W.; Chen, C. H. Laser-induced acoustic desorption mass spectrometry of single bioparticles. Angew. Chem. Int. Ed. 2006, 45, 1423-1426. (24) Xiong, C.; Zhou, X.; Wang, J.; Zhang, N.; Peng, W.-P.; Chang, H.-C.; Nie, Z. Ambient Aerodynamic Desorption/Ionization Method for Microparticle Mass Measurement. Anal. Chem. 2013, 85, 4370-4375. (25) Chang, H.-C. Ultrahigh-Mass Mass Spectrometry of Single Biomolecules and


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Bioparticles. Annual Review of Anal. Chem. 2009, 2, 169-185. (26) Peng, W.-P.; Chou, S.-W.; Patil, A. A. Measuring masses of large biomolecules and bioparticles using mass spectrometric techniques. Analyst 2014, 139, 3507-3523. (27) Nie, Z. X.; Tzeng, Y. K.; Chang, H. C.; Chiu, C. C.; Chang, C. Y.; Chang, C. M.; Tao, M. H. Microscopy-based mass measurement of a single whole virus in a cylindrical ion trap Angew. Chem. Int. Ed. 2006, 45, 8131-8134. (28) Dow, A.; Wittrig, A.; Kenttämaa, H. Laser-induced acoustic desorption (LIAD) mass spectrometry. Eur. J. of Mass Spectrom. 2012, 18, 77-92. (29) Habicht, S. C.; Amundson, L. M.; Duan, P.; Vinueza, N. R.; Kenttämaa, H. I. Laser-Induced Acoustic Desorption Coupled with a Linear Quadrupole Ion Trap Mass Spectrometer. Anal. Chem. 2010, 82, 608-614. (30) Golovlev, V. V.; Allman, S. L.; Garrett, W. R.; Taranenko, N. I.; Chen, C. H. Laser-induced acoustic desorption, Int. J. Mass Spectrom. Ion Process. 1997, 169–170, 69-78. (31) Field, F. H.; Head, H. N.; Franklin, J. L. Ionic Reactions in Krypton-Methane and Argon-Methane Mixtures. J. Am. Chem. Soc. 1962, 84, 1118-1122. (32) Melton, C. E. Charge Transfer Reactions Producing Intrinsic Chemical Change: Methyl, Methylene, and Hydrogen Radicals Produced from Argon and Methane Reactions. J. Chem. Phys. 1960, 33, 647-651. (33) Bogaerts, A. Hybrid Monte Carlo — Fluid model for studying the effects of nitrogen addition to argon glow discharge. Spectrochim. Acta B. 2009, 64, 126-140. (34) Chou, S.-W.; Shiu, G.-R.; Chang, H.-C.; Peng, W.-P. Wavelet-Based Method for Time-Domain Noise Analysis and Reduction in a Frequency-Scan Ion Trap Mass Spectrometer. J. Am. Soc. Mass Spectrom. 2012, 23, 1855-1864. (35) Lewis, C. L.; Craig, C. C.; Senecal, A. G. Mass and Density Measurements of Live and Dead Gram-Negative and Gram-Positive Bacterial Populations. Appl. Environ. Microbiol. 2014, 80, 3622-3631. (36) Feijó Delgado, F.; Cermak, N.; Hecht, V. C.; Son, S.; Li, Y.; Knudsen, S. M.; Olcum, S.; Higgins, J. M.; Chen, J.; Grover, W. H.; Manalis, S. R. Intracellular Water Exchange for Measuring the Dry Mass, Water Mass and Changes in Chemical Composition of Living Cells. PLOS ONE 2013, 8, e67590. (37) Burg, T. P.; Godin, M.; Knudsen, S. M.; Shen, W.; Carlson, G.; Foster, J. S.; Babcock, K.; Manalis, S. R. Weighing of biomolecules, single cells and single nanoparticles in fluid. Nature 2007, 446, 1066-1069. (38) Gupta, A.; Akin, D.; Bashir, R. Single virus particle mass detection using microresonators with nanoscale thickness. Appl. Phys. Lett. 2004, 84, 1976-



(39)

(40) (41) (42)

1978. Johnson, L.; Gupta, A. K.; Ghafoor, A.; Akin, D.; Bashir, R. Characterization of vaccinia virus particles using microscale silicon cantilever resonators and atomic force microscopy. Sens. Actuators B: Chem. 2006, 115, 189-197 Heck, A. J. R. Native mass spectrometry: a bridge between interactomics and structural biology. Nat. Methods 2008, 5, 927-933. van Duijn, E. Current Limitations in Native Mass Spectrometry Based Structural Biology. J. Am. Soc. Mass Spectrom. 2010, 21, 971-978. Peck, J.; Gonzalez, L. A.; Williams, L. R.; Xu, W.; Croteau, P. L.; Timko, M. T.;

Jayne, J. T.; Worsnop, D. R.; Miake-Lye, R. C.; Smith, K. A. Development of an aerosol mass spectrometer lens system for PM2.5. Aerosol Sci. Tech. 2016, 50, 781-789. (43) Zhang, Y.; Tang, L.; Croteau, P. L.; Favez, O.; Sun, Y.; Canagaratna, M. R.; Wang, Z.; Couvidat, F.; Albinet, A.; Zhang, H.; Sciare, J.; Prévôt, A. S. H.; Jayne, J. T.; Worsnop, D. R. Field characterization of the PM2.5 Aerosol Chemical Speciation Monitor: insights into the composition, sources and processes of fine particles in Eastern China. Atmos. Chem. Phys. Discuss. 2017, 2017, 1-52. (44) Yang, J.; Ma, S.; Gao, B.; Li, X.; Zhang, Y.; Cai, J.; Li, M.; Yao, L. a.; Huang, B.; Zheng, M. Single particle mass spectral signatures from vehicle exhaust particles and the source apportionment of on-line PM2.5 by single particle aerosol mass spectrometry. Sci. Total Environ. 2017, 593–594, 310-318. (45) Kumar, S.; Verma Mukesh, K.; Srivastava Anup, K. Ultrafine particles in urban ambient air and their health perspectives. Rev. Environ. Health. 2013, p 117. (46) Li, N.; Georas, S.; Alexis, N.; Fritz, P.; Xia, T.; Williams, M. A.; Horner, E.; Nel, A. A work group report on ultrafine particles (American Academy of Allergy, Asthma & Immunology): Why ambient ultrafine and engineered nanoparticles should receive special attention for possible adverse health outcomes in human subjects, Journal of Allergy and Clinical Immunology. J. Allergy. Clin. Immunol. 2016, 138, 386-396. (47) Snyder, D. T.; Pulliam, C. J.; Ouyang, Z.; Cooks, R. G. Miniature and Fieldable Mass Spectrometers: Recent Advances. Anal. Chem. 2016, 88, 2-29.


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Figure Captions Figure 1 a) Experimental setup of laser-induced RF plasma (LIRFP) charge detection quadrupole ion trap mass spectrometer (CD QIT-MS). The Nd:YAG laser induces particle desorption and triggers the RF plasma. The inset shows the plume formation by LIRFP. b) Desorption, ionization and detection of particles (from left to right). Figure 2 Charge distributions of 0.75 m polystyrene particles using reagent gases of a) argon, b) a mixture of argon and methane (ratio of 10:1), c) nitrogen, d) air and e) a mixture of argon and nitrogen (ratio of 1:1). The plasma colors in inset of Figures 2a, 2b, 2c, 2d and 2e are purple, bright white, bright pink, pink and fuchsia respectively. The ion trapping voltage is set at voltage 0.4kV0-p and rf frequency is scanned from 6000 to 100Hz. Figure 3 Single scan mass spectra of a) Escherichia coli EC11303, b) Staphylococcus aureus, c) Escherichia coli strain W, and d) vaccinia virus. The y-axis of ion charge number (z) is converted from the charge detector ion signal. Using a known test pulse calibration, the charge conversion gain is approximately 29.8e/1 mV. The ion trapping voltage and rf frequency scan settings are shown in the supporting information. Mixture of argon and methane with ratio of 10:1 is used in this experiment. Figure 4 Mass (a-d) and charge (e-h) distributions for variously sized bacterial and viral particles. Each count represents a single detected bacterial and viral particle.



Figure 1 a)

b)


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Page 23 of 26

Figure 2 a)

b) Argon

120

Argon/methane mixture (10:1)

90

1631

Counts

Counts

837 60

0

0

1000

2000

0

d)

Counts

Counts

120

0

1000

e)

2000

3000

618 40

0

0

Argon/nitrogen mixture (1:1)

80

0

1000

1000 Charge

798

0

2000

6000

Air

Charge 160

4000

80

711

0

2000 Charge

Nitrogen

240

45

0

3000

Charge

c)

Counts

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


3000

Charge


2000


Figure 3 b)

a) Escherichia coli (EC11303)

Charge (-z)

1000

0

-1000

-1000

-2000

-2000

-3000

-3000

-4000

-4000 4.0

4.5

5.0

Staphylococcus aureus

1000

0

-5000 3.5

-5000 4.5

5.5

5.0

5.5

m/z (107)

c) Escherichia coli (strain W)

0

-1000

-500

-2000

-1000

-3000

-1500 4.8

5.6

6.4

6.5

7.0

Vaccinia virus

500

0

-4000

6.0

m/z (107)

d) 1000

Charge (-z)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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-2000 1.4

m/z (107)

1.5

1.6 m/z (107)


1.7

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Figure 4 a)

b)

60

Counts

(3.5 1.4)

Counts 0

c)

11

1x10

60

11

11

2x10 3x10 Mass (Da)

d)

11

Counts 11

11



30

0 0.0

11

3x10

11

2.4x10

Vaccinia virus

(9.1  3.5)

1x10 2x10 Mass (Da)

11

1.2x10 1.8x10 Mass (Da)



e)

10

10

2.0x10 4.0x10 Mass (Da)

10

6.0x10

f) 50

60

Escherichia coli strain W

Escherichia coli EC11303

1112

842

Counts

Counts

10

6.0x10

60

30

0



40

0 0.0

11

4x10

Staphylococcus aureus

(5.6 2.0)

0

Escherichia coli EC11303



30

0

Counts

80

Escherichia coli strain W

(6.0 2.5)

25

0

0

1000

2000 3000 Charge (z)

g) 60

4000

30

0

5000

1000

h) 60

Staphylococcus Aureus

Counts 0

1000

4000

708

30

0

2000 3000 Charge (z)

Vaccinia virus

971

Counts

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


2000 3000 Charge (z)

4000

30

0

0

1000

2000 3000 Charge (z)


4000

5000


TOC graphic


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Ionization of Submicron-Sized Particles by Laser-Induced RF Plasma

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