High-Performance Sample Substrate of Gold Nanoparticle Multilayers for Surface-Assisted Laser Desorption/Ionization Mass Spectrometry.

Liu Liu,Lin Lin,Chang Chang,Kuo Kuo,Liou Liou

doi:10.3390/nano9081078

Abstract

The development of a sample substrate with superior performance for desorption and ionization of analyte is the key issue to ameliorate the quality of mass spectra for measurements of small molecules in surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). Herein, the homogeneous sample substrate of gold nanoparticle multilayers (AuNPs-ML) with hexagonal lattice was successfully prepared by self-assembly technique. With strong surface plasmon resonance absorption and superior photothermal effect, the sample substrate of AuNPs-ML exhibited high signal sensitivity and low background noise for the detection of model analyte of glucose without additional matrixes in SALDI-MS. Furthermore, compared to merchant matrixes of α-cyano-4-hydroxycinnamic acid (CHCA) and 2,5-dihydroxybenzoic acid (DHB), the sample substrate of AuNPs-ML was demonstrated to ameliorate the quality of mass spectra, including signal strength, background interference and signal/noise (S/N) ratio. The sucrose and tryptophan were also measured to show the extensive applications of AuNPs-ML sample substrate for the detections of small molecules in SALDI-MS. Most importantly, the remarkable reproducibility of glucose mass spectra with relative signal of 7.3% was obtained by the use of AuNPs-ML sample substrate for SALDI-MS. The homogeneous sample substrate of AuNPs-ML greatly improved the quality of mass spectra because of its strong absorption of laser energy, low specific heat, high heat conductivity and extraordinary homogeneity. We believe that AuNPs-ML could be a practical sample substrate for small molecule detection in SALDI-MS.

Highlights

Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) has been extensively utilized for the analyses of small molecules (m/z < 500 Da) such as drugs, pesticides and biomolecules [1,2,3,4,5,6,7,8,9,10,11]
With the use of HgTe nanostructures as a matrix and sucralose as an internal standard, the contents of monosaccharides and disaccharides in honey samples have been measured with short time (
There are still some crucial issues that need to be addressed such as the increase of signal intensity, decrease of background noise and improvement of sample reproducibility

Summary

Introduction

Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) has been extensively utilized for the analyses of small molecules (m/z < 500 Da) such as drugs, pesticides and biomolecules [1,2,3,4,5,6,7,8,9,10,11]. With the applications of nanomaterials as the assisted matrixes, SALDI-MS has shown specific advantages included facile sample fabrication, strong sample signal, less background noise and excellent salt tolerance [12,13,14,15,16,17]. Various nanomaterials such as semiconductor, metal, and metal oxide have been widely applied as superior matrixes due to their intense light absorption, large surface area and high stability, resulting in high signal/noise (S/N) ratio for small molecules [18,19,20,21,22]. The gold nanoparticles were dispersed in hexane for further experiments

Fabrication of Self-Assembled Monolayer of Gold Nanoparticles

SALDI-MS Measurements

Structural and Optical Properties of Gold Nanoparticles

Merchant Matrixes and AuNPs-ML for SALDI-MS Measurements

Detections of Sucrose and Trryyppttoopphhaann