Wall-less sample preparation of <i>μ</i>m-sized sample spots for femtomole detection limits of proteins from liquid based UV-MALDI matrices

Bogan, Michael J.; Agnes, George R.

doi:10.1016/j.jasms.2003.11.012

Cited by 20 publications

(22 citation statements)

References 27 publications

(34 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Either static or programmed changes in the potentials applied to the electrodes comprising the EDB could be used to cause the droplet to be ejected when its m/z reaches a certain critical value, or those potentials can be set to retain the droplet within the EDB indefinitely. Importantly, the ejection of each droplet from the EDB can be controlled, and each droplet can be deposited at a known location on a substrate which allows subsequent manipulation and characterization of it [19]. Furthermore, translation of the substrate plate between droplet deposition events allows arrays of droplet residues to be formed [19], and it will be shown that they are ordered according to the m/z of the levitated droplet residues.…”

Section: Droplet Levitationmentioning

confidence: 99%

“…Importantly, the ejection of each droplet from the EDB can be controlled, and each droplet can be deposited at a known location on a substrate which allows subsequent manipulation and characterization of it [19]. Furthermore, translation of the substrate plate between droplet deposition events allows arrays of droplet residues to be formed [19], and it will be shown that they are ordered according to the m/z of the levitated droplet residues.…”

Section: Droplet Levitationmentioning

confidence: 99%

See 1 more Smart Citation

Promotion of α-cyano-4-hydroxycinnamic acid and peptide cocrystallization within levitated droplets with net charge

Bogan

Bakhoum

Agnes

2005

J. Am. Soc. Mass Spectrom.

Self Cite

View full text Add to dashboard Cite

Many reactions occur as a result of charge imbalance within or between reactive species in reaction vessels that have zero net charge. Here, chemical processes taking place within reaction vessels having net excess charge were studied. For mass spectroscopists, a familiar example of vessels that defy electroneutrality are the charged droplets produced by an electrospray ion source. Evidence is presented that control of the magnitude of the net charge contained in a reaction vessel, in this case a levitated droplet, can be used to promote nucleation and crystal growth of a mixture of an organic acid, ␣-cyano-4-hydroxycinnamic acid (CHCA), with one or more peptides. This phenomenon was first observed during our ongoing development of wall-less sample preparation (WaSP), electrodynamic charged droplet processing methodology capable of creating micrometer-sized sample spots for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) from subnanoliter volumes of sample material. Peptide ion signal-to-noise (S/N) ratios obtained by MALDI-TOF-MS from sample spots created from droplets that had high relative magnitude of net charge were consistently greater than those detected from sample spots created from droplets that had lower net charge. To study this unexpected phenomenon further, WaSP methodology was developed to process different mass-to-charge (m/z) droplets levitated in an electrodynamic balance (EDB), facilitating their deposition onto different positions of a target to create arrays of droplet residues ordered from highest to lowest m/z. This capability allowed simultaneous levitation with subsequent separation of a population of droplets created from a single starting solution, but the droplets had varied magnitudes of net charge. After the droplets were ejected from the EDB and collected on a glass slide or MALDI plate, the solids contained in the deposited droplets were characterized using microscopy and MALDI-TOF-MS. T he physics of droplets that possess net charge is a subject that continues to receive considerable theoretical and experimental attention 140 years after initial independent studies by Lord Kelvin and Lord Rayleigh [1][2][3][4][5][6][7]. Less well characterized is the condensed phase chemistry that could occur within such droplets as a result of the net charge that is localized in the diffuse layer at the droplet-air interface [8,9]. Such chemistry could be rich. For instance, mass spectrometry studies of cluster ions released from charged droplets in an electrospray have identified shifts in chemical equilibria and the formation of preferred nanocrystalline structures [10 -14]. It is possible that these perturbations in the chemical processing are dominated by effects that transpire because the reaction vessels defy electroneutrality.Here we apply electrodynamic levitation technology [15][16][17], microscopy, and MALDI-MS to characterize chemistry that occurred within levitated droplets as a function of the magnitude of their net charge. Droplets were d...

show abstract

Section: Droplet Levitationmentioning

confidence: 99%

Section: Droplet Levitationmentioning

confidence: 99%

Promotion of α-cyano-4-hydroxycinnamic acid and peptide cocrystallization within levitated droplets with net charge

Bogan

Bakhoum

Agnes

2005

J. Am. Soc. Mass Spectrom.

Self Cite

View full text Add to dashboard Cite

show abstract

“…A number of groups, including our own, are exploring robotic devices as tools for increasing the reproducibility of submicroliter volumes of matrix solution deposited onto tissue sections (21)(22)(23)(24)(25). Microspots of matrix with diameters on the order of 200 -300 m can be generated with greater speed and precision than manual methods, allowing arrays of hundreds of matrix microspots to be deposited in a matter of minutes.…”

mentioning

confidence: 99%

A Novel Histology-directed Strategy for MALDI-MS Tissue Profiling That Improves Throughput and Cellular Specificity in Human Breast Cancer

Cornett

Mobley

Dias

et al. 2006

Molecular & Cellular Proteomics

175

149

View full text Add to dashboard Cite

We describe a novel tissue profiling strategy that improves the cellular specificity and analysis throughput of protein profiles obtained by direct MALDI analysis. The new approach integrates the cellular specificity of histology, the accuracy and reproducibility of robotic liquid dispensing, and the speed and objectivity of automated spectra acquisition. Traditional methodologies for preparing and analyzing tissue samples rely heavily on manual procedures, which for various reasons discussed, restrict cellular specificity and sample throughput. Here, a robotic spotter deposits micron-sized droplets of matrix precisely onto foci of normal mammary epithelium, ductal carcinoma in situ, invasive mammary cancer, and peritumoral stroma selected by a pathologist from high resolution histological images of sectioned human breast cancer samples. The location of each matrix spot was then determined and uploaded into the instrument to facilitate automated profile acquisition by MALDI-TOF. In the example shown, the different lesions were clearly differentiated using mass profiling. Further, the workflow permits a visual projection of any information produced from the profile analyses directly on the histological image for a unique combination of proteomic and histological assessment of sample regions. The higher performance characteristics offered by the new workflow promises to be a significant advancement toward the next generation of tissue profiling studies. Molecular & Cellular Proteomics 5: 1975-1983, 2006.

show abstract

“…23,24 Briefly, an electrode, referred to as the induction electrode, was positioned 3 mm from the orifice of the droplet dispenser. Variation of the DC potential applied to the induction electrode (IP f , the induction potential during droplet formation) proportionally varied the magnitude of the image charge imparted onto the forming droplets.…”

Section: Electrodynamic Charged Droplet Processing: Waspmentioning

confidence: 99%

“…Wall-less sample preparation (WaSP) 23,24 is a methodology that utilizes electrodynamic levitation technology, [25][26][27] in the form of a double-ring electrodynamic balance (EDB), to control the trajectories of picoliter volume charged droplets dispensed from a droplet-on-demand piezoelectric droplet dispenser. The levitated droplets can be deposited onto a target plate with high spatial accuracy, facilitating their analysis external to the EDB.…”

mentioning

confidence: 99%

Preliminary investigation of electrodynamic charged droplet processing to couple capillary liquid chromatography with matrix‐assisted laser desorption/ionization mass spectrometry

Bogan¹,

Agnes²

2004

Rapid Comm Mass Spectrometry

Self Cite

View full text Add to dashboard Cite

Charged droplet processing methodology, that utilizes electrodynamic levitation technology to control the trajectories of picoliter volume charged droplets and deliver them to a target plate at atmospheric pressure, has been developed. Termed wall-less sample preparation (WaSP), this methodology offers several features that could prove beneficial to the preparation of sample spots from separation column effluents for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis. These features include solute pre-concentration factors of 10(1) to 10(3) due to volatile solvent evaporation prior to droplet deposition onto the target plate, high spatial accuracy of the deposition position of each processed droplet (+/-5 microm), and the ability to prepare sample spots as small as 20 microm in diameter from a single droplet. Here a new mode of operation of this methodology is described and used as an offline post-column pre-concentrating interface between capillary liquid chromatography (capLC) and a target plate for offline MALDI-MS. Using a fraction from the capLC separation of peptides produced by the proteolytic digestion of the protein cytidine 5'-triphosphate:phosphocholine cytidylyltransferase, MALDI sample spots were prepared using the dried-droplet method, direct piezoelectric droplet dispensing, and the processing of piezo-dispensed droplets by WaSP. The sample spot morphology was investigated using light microscopy, and peptide ion abundances produced by MALDI were measured using time-of-flight (TOF) MS. The advantages of developing an online capLC/WaSP interface with MALDI-MS in the future are discussed along with some of the challenges that may be encountered in such an endeavor.

show abstract

Wall-less sample preparation of μm-sized sample spots for femtomole detection limits of proteins from liquid based UV-MALDI matrices

Cited by 20 publications

References 27 publications

Promotion of α-cyano-4-hydroxycinnamic acid and peptide cocrystallization within levitated droplets with net charge

Promotion of α-cyano-4-hydroxycinnamic acid and peptide cocrystallization within levitated droplets with net charge

A Novel Histology-directed Strategy for MALDI-MS Tissue Profiling That Improves Throughput and Cellular Specificity in Human Breast Cancer

Preliminary investigation of electrodynamic charged droplet processing to couple capillary liquid chromatography with matrix‐assisted laser desorption/ionization mass spectrometry

Contact Info

Product

Resources

About