title: Direct analysis of intact biological macromolecules by low-energy, fiber-based femtosecond laser vaporization at 1042 nm wavelength with nanospray postionization mass spectrometry.
abstract: A fiber-based laser with a pulse duration of 435 fs and a wavelength of 1042 nm was used to vaporize biological macromolecules intact from the condensed phase into the gas phase for nanospray postionization and mass analysis. Laser vaporization of dried standard protein samples from a glass substrate by 10 Hz bursts of 20 pulses having 10 μs pulse separation and <50 μJ pulse energy resulted in signal comparable to a metal substrate. The protein signal observed from an aqueous droplet on a glass substrate was negligible compared to either a droplet on metal or a thin film on glass. The mass spectra generated from dried and aqueous protein samples by the low-energy, fiber laser were similar to the results from high-energy (500 μJ), 45-fs, 800-nm Ti:sapphire-based femtosecond laser electrospray mass spectrometry (LEMS) experiments, suggesting that the fiber-based femtosecond laser desorption mechanism involves a nonresonant, multiphoton process, rather than thermal- or photoacoustic-induced desorption. Direct analysis of whole blood performed without any pretreatment resulted in features corresponding to hemoglobin subunit-heme complex ions. The observation of intact molecular ions with low charge states from protein, and the tentatively assigned hemoglobin α subunit-heme complex from blood suggests that fiber-based femtosecond laser vaporization is a "soft" desorption source at a laser intensity of 2.39 × 10(12) W/cm(2). The low-energy, turnkey fiber laser demonstrates the potential of a more robust and affordable laser for femtosecond laser vaporization to deliver biological macromolecules into the gas phase for mass analysis.
authors: †Department of Chemistry, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States.|‡Center for Advanced Photonics Research, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States.
authors: Fengjian
authors: F
authors: Shi
authors: †Department of Chemistry, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States.|‡Center for Advanced Photonics Research, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States.
authors: Paul M
authors: PM
authors: Flanigan
authors: †Department of Chemistry, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States.|‡Center for Advanced Photonics Research, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States.
authors: Jieutonne J
authors: JJ
authors: Archer
authors: †Department of Chemistry, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States.|‡Center for Advanced Photonics Research, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States.
authors: Robert J
authors: RJ
authors: Levis
mesh_terms: D000818:Animals; D045304:Cytochromes c / Q000737:chemistry*; D005898:Glass / Q000737:chemistry; D007834:Lasers; D009113:Muramidase / Q000737:chemistry*; D055100:Optical Fibers; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation*; D013193:Stainless Steel / Q000737:chemistry; D013997:Time Factors; D014835:Volatilization; D014867:Water / Q000737:chemistry; D015018:Ytterbium
chemical_list: D014867:Water; D013193:Stainless Steel; D045304:Cytochromes c; D009113:Muramidase; D015018:Ytterbium