Laser surface enhanced

RBS Rutherford backscattering SELDI Surface-enhanced laser desorption... 

Wright, G. L., Cazares, L. H., Leung, S.-M., Nasim, S., Adam, B.-L., Yip, T.-T., Schellhammer, P. F., Gong, L., and Vlahou, A. (2000). ProteinChip surface enhanced laser desorption/ionization (SELDI) mass spectrometry a novel protein biochip technology for detection of prostate cancer biomarkers in complex protein mixtures. Prostate Cancer and Prostatic Diseases 2, 264-276. 

The ProteinChip System from Ciphergen Biosystems uses patented SELDI (Surface-Enhanced Laser Desorption/Ionization) ProteinChip technology to rapidly perform the separation, detection, and analysis of proteins at the femtomole level directly from biological samples. ProteinChip Systems use ProteinChip Arrays which contain chemically (cationic, anionic, hydrophobic, hydrophilic, etc.) or biochemically (antibody, receptor, DNA, etc.) treated surfaces for specific interaction with proteins of interest. Selected washes create on-chip, high-resolution protein maps. This protein mass profile, or reten-tate map of the proteins bound to each of the ProteinChip Array surfaces, is quantitatively detected in minutes by the ProteinChip Reader. 

Diamond DL, Zhang Y, Gaiger A, et al. Use of ProteinChip array surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) to identify thymosin beta-4, a differentially secreted protein from lymphoblastoid cell lines. J. Am. Soc. Mass Spectrom. 2003 14 760-765. 

Merkel, D., et al., Proteomic study of human bronchoalveolar lavage fluids from smokers with chronic obstructive pulmonary disease by combining surface-enhanced laser desorp-tion/ionization-mass spectrometry profiling with mass spectrometric protein identification, Proteomics. 5, 11, 2972, 2005. 

Also for MALDI, there is a special case worth mentioning. Surface-enhanced laser desorption/ionization (SELDI) is a technique that utilizes special sample plates [196, 197]. These have different modified surfaces, for example, hydrophobic, anionic, or antibody treated. Which type of surface to select depends on the application. After application of analyte the surface is washed according to a protocol leaving only the desired components on the target. Finally, a MALDI matrix is applied before analysis in the spectrometer. See Chapter 12 for an application example of SELDI. 

Surface enhanced laser desorption/ionization (SELDI) is a distinctive form of laser desorption ionization where the target plays an active role in the sample preparation procedure and ionization process [49]. Depending on the chemical or biochemical treatment, the SELDI surface acts as solid phase extraction or an affinity probe. Chromatographic surface is used for sample fractionation and purification of biological samples prior to direct analysis by laser desorption/ ionization. SELDI is mainly applied for protein profiling and in biomarker discovery by comparing protein profiles from control and patient groups. 

The analysis for proteins present in plasma or a cell extract is a challenging task due to their complexity and the great difference between protein concentrations present in the sample. Simple mixtures of intact proteins can be analyzed by infusion with electrospray ionization and more complex ones by matrix assisted laser desorption ionization. MALDI is more suited for complex mixtures because for each protein an [M+H]+ signal is observed while for ESI multiply charged ions are observed. Surface enhanced laser desorption (SEEDI) is a technique for the screening of protein biomarkers based on the mass spectrometric analysis of intact proteins [49]. However in most cases for sensitivity reasons mass spec-... 

Boyle, M.D.P., Romer, T.G., Meeker, A.K., and Sledjeski, D.D., Use of surface-enhanced laser desorption ionization protein chip system to analyze streptococcal exotoxin B activity secreted by Streptococcus pyogenes, ]. Microbiol. Meth., 46, 87-89, 2001. 

Dare TO, Davies HA, Turton JA, et al. Apphcation of surface-enhanced laser desorption/ionization technology to the detection and identification of urinary parvalbumin-alpha a biomarker of compoimd-induced skeletal muscle toxicity in the rat. Electrophoresis 2002 23 3241-51. 

In a related approach, arrays with different types of surface chemistries such as hydrophobic, hydrophilic, anionic, and affinity are used to absorb certain protein groups from biological or patient samples. The chip-absorbed proteins are then directly detected by surface-enhanced laser desorption/ionization time-of-flight MS (SELDl-TOF MS) (Issaq et al. 2002). The resulting protein masses can be used in pattern analysis and thereby provide a useful diagnostic tool. 

Proteomics has the potential to revolutionize diagnosis and disease management. Profiling serum protein patterns by means of surface-enhanced laser desorption/ion-isation time of flight (SELDI-TOFF) mass spectrometry is a novel approach to... 

Mass spectrometers are used not only to detect the masses of proteins and peptides, but also to identify the proteins, to compare patterns of proteins and peptides, and to scan tissue sections for specific masses. MS is able to do this by giving the mass-to-charge ratio of an ionized species as well as its relative abundance. For biological sample analysis, mass spectrometers are connected to an ionizing source, which is usually matrix-assisted laser desorption ionization (MALDI) [14], surface-enhanced laser desorption/ioni-zation (SELDI, a modified form of MALDI) [15], or electrospray ionization [16]. These interfaces enable the transfer of the peptides or proteins from the solid or liquid phase, respectively, to the gas (vacuum) phase inside the mass spectrometer. Both MALDI and electrospray ionization can be connected to different types of mass analyzers, such as quadrupole, quadruple-ion-traps, time of flight (TOF), or hybrid instruments such as quadrupole-TOF or Fourier transform-ion cyclotron resonance. Each of these instruments can... 

FT-ICR-Fourier transform-ion cyclotron resonance. MALDI-matrix-assisted laser desorption ionization. SELDI-surface-enhanced laser desorption/ionization. 

Mian S, Ball G, Hornbuckle J, et al. A prototype methodology combining surface-enhanced laser desorption/ionization protein chip technology and artificial neural network algorithms to predict the chemoresponsiveness of breast cancer cell lines exposed to Paclitaxel and Doxorubicin under in vitro conditions. Proteomics 2003 3(9) 1725-1737. 

Matrix-assisted laser desorption ionization (MALDI) and surface-enhanced laser desorption ionization (SELDI) have been used online with TOF-MS for protein differential profiles of intact or hydrolyzed biological matrices in proteomics. The potential use of affinity chips, grafted with specific Ab towards the drug compound for MALDI or SELDI, will bring sensitive and selective tools for macromolecules. Specific Ab towards either the intact protein or several signature peptides... 

FIGURE 7 Group B streptococcus infection-induced differential protein expression in nonhuman primate (A) and human (B) amniotic fluid samples by surface-enhanced laser desorption/ionization (SELDI-TOF MS) using normal-phase protein chip arrays. Spectrum from 2.5 to 15 kDa collected at 235 nm laser intensity. Detailed spectra show increased expression of the 3.5 and 10.8 kDa peaks between control and infected. Arrows indicate the unique peaks represented by polypeptides overexpressed in infection. 

Surface-Enhanced Laser Desorption-Ionization Protein Profiling... 

Banks RE, Stanley AJ, Cairns DA, Barrett JH, Clarke P, Thompson D, et al. Influences of blood sample processing on low-molecular-weight proteome identified by surface-enhanced laser desorption/ionization mass spectrometry. Clin Chem 2005 51(9) 1637 1649. 

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