title: Surface modified BaTiO3 nanoparticles as the matrix for phospholipids and as extracting probes for LLME of hydrophobic proteins in Escherichia coli by MALDI-MS.
abstract: In this paper, we report the dual function of 12-hydroxy octadecanoic acid (HOA)-modified barium titanate nanoparticles (BaTiO3 NPs) as the matrix for phospholipids (PLs) and as hydrophobic affinity probes for liquid-liquid microextraction (LLME) of hydrophobic proteins in Escherichia coli prior to their identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-MS). FT-IR, SEM and TEM were used for the characterization of the HOA-modified BaTiO3 NPs. The surface modified BaTiO3 NPs acted as multifunctional probes (as extracting probes and as the matrix) for the analysis of PLs by MALDI-MS. Compared to 2,5-dihydroxybenzoic acid (2,5-DHB), the HOA-modified BaTiO3 NPs provided good PLs mass spectra with similar or improved signal-to-noise (S/N) ratio, which demonstrated the potentiality of HOA-modified BaTiO3 NPs as a PLs purpose matrix. This method was found to be linear in concentration ranges of 1.0-5.0 μM and 1.0-10.0 μM for L-A-phosphatidyl-l-serine (PS) and L-A-phsophatidic acid sodium (PA) with correlation coefficient (R(2)) values from 0.9905 to 0.9987. The detection limits were 0.20-0.35 μM and 0.25-0.40 μM for PS and PA, respectively. We also demonstrated the HOA-modified BaTiO3 NPs as extracting and as preconcentrating probes for the LLME of hydrophobic proteins in E. coli prior to their identification by MALDI-MS. Thus, the surface modified BaTiO3 NPs-assisted LLME coupled with MALDI-MS provides a simple methodology for the efficient extraction and determination of hydrophobic molecules in biological samples.
authors: Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, 80424, Taiwan.
authors: Suresh Kumar
authors: SK
authors: Kailasa
authors: Hui-Fen
authors: HF
authors: Wu
mesh_terms: D001426:Bacterial Proteins / Q000302:isolation & purification*; D017609:Barium Compounds / Q000737:chemistry*; D004926:Escherichia coli / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D059627:Liquid Phase Microextraction; D053768:Metal Nanoparticles / Q000737:chemistry*; D010712:Phosphatidic Acids / Q000032:analysis*; D010718:Phosphatidylserines / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014025:Titanium / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D017609:Barium Compounds; D010712:Phosphatidic Acids; D010718:Phosphatidylserines; C024547:barium titanate(IV); D014025:Titanium
keywords: E. coli; FT-IR; HOA-modified BaTiO(3) NPs; MALDI–MS; PLs; TEM