title: Characterization of rhodamine self-assembled films using desorption electrospray ionization mass spectrometry.
abstract: Growth process information and molecular structure identification are very important for characterization of self-assembled films. Here, we explore the possible application of desorption electrospray ionization mass spectrometry (DESI-MS) that provides the assembled information of rhodamine B (Rh B) and rhodamine 123 (Rh 123) films. With the help of lab-made DESI source, two characteristic ions [Rh B](+) and [Rh 123](+) are observed directly in the open environment. To evaluate the reliability of this technique, a comparative study of ultraviolet-visible (UV-vis) spectroscopy and our method is carried out, and the result shows good correlation. According to the signal intensity of characteristic ions, the layer-by-layer adsorption process of dyes can be monitored, and the thicknesses of multilayer films can also be comparatively determined. Combining the high sensitivity, selectivity, and speed of mass spectrometry, the selective adsorption of similar structure molecules under different pH is recognized easily from extracted ion chronograms. The variation trend of dyes signalling intensity with concentration of polyelectrolyte is studied as well, which reflects the effect of surface charge on dyes deposition. Additionally, the desorption area, surface morphology, and thicknesses of multilayer films are investigated using fluorescence microscope, scanning electron microscope (SEM), and atomic force microscopy (AFM), respectively. Because the desorption area was approximately as small as 2 mm(2), the distribution situation of organic dyes in an arbitrary position could be gained rapidly, which means DESI-MS has advantages on in situ analysis.
authors.affiliation: College of Chemistry, Beijing Normal University, Beijing, People's Republic of China.
authors.forename: Ruixia
authors.initials: R
authors.lastname: Shi
authors.forename: Na
authors.initials: N
authors.lastname: Na
authors.forename: Fubin
authors.initials: F
authors.lastname: Jiang
authors.forename: Jin
authors.initials: J
authors.lastname: Ouyang
mesh_terms: D000327:Adsorption; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D020112:Rhodamine 123 / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D007477:Ions; D012235:Rhodamines; D020112:Rhodamine 123; C029773:rhodamine B
references.citation: Pharm Res. 2003 Aug;20(8):1192-9
references.pmid: 12948017
references.citation: Talanta. 2011 Aug 15;85(2):1187-92
references.pmid: 21726757
references.citation: Langmuir. 2008 Oct 7;24(19):10887-94
references.pmid: 18785708
references.citation: Chemistry. 2012 Feb 6;18(6):1761-71
references.pmid: 22237915
references.citation: Analyst. 2010 Apr;135(4):669-81
references.pmid: 20309441
references.citation: Anal Bioanal Chem. 2008 Jul;391(5):1783-91
references.pmid: 18425500
references.citation: J Mass Spectrom. 2005 Oct;40(10):1261-75
references.pmid: 16237663
references.citation: Science. 2004 Oct 15;306(5695):471-3
references.pmid: 15486296
references.citation: Anal Bioanal Chem. 2010 Sep;398(1):265-94
references.pmid: 20521143
references.citation: Chem Commun (Camb). 2006 Apr 28;(16):1709-11
references.pmid: 16609779
references.citation: J Colloid Interface Sci. 2008 Aug;324(1-2):156-66
references.pmid: 18533177
references.citation: ACS Appl Mater Interfaces. 2010 Jun;2(6):1556-60
references.pmid: 20496943
references.citation: Rapid Commun Mass Spectrom. 2008;22(4):503-10
references.pmid: 18215006
references.citation: Langmuir. 2011 Jan 18;27(2):782-91
references.pmid: 21162522
references.citation: J Phys Chem B. 2008 Oct 2;112(39):12201-7
references.pmid: 18774851
references.citation: Lab Chip. 2005 Feb;5(2):163-70
references.pmid: 15672130
references.citation: Anal Chem. 2009 Mar 15;81(6):2286-93
references.pmid: 19281262
references.citation: Analyst. 2010 Apr;135(4):720-5
references.pmid: 20349537
references.citation: Macromol Biosci. 2009 Aug 11;9(8):776-85
references.pmid: 19340816
references.citation: Anal Chem. 2007 Jul 15;79(14):5479-83
references.pmid: 17555293
references.citation: Langmuir. 2007 Dec 18;23(26):13046-52
references.pmid: 18004897
references.citation: Anal Bioanal Chem. 2008 May;391(1):317-24
references.pmid: 18264700
references.citation: J Am Chem Soc. 2003 Jul 23;125(29):8911-5
references.pmid: 12862487