Detection of Proteins and Protein−Ligand Complexes Using HgTe Nanostructure Matrixes in Surface-Assisted Laser Desorption/Ionization Mass Spectrometry

Abstract

We have analyzed peptides, proteins, and protein-drug complexes through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using HgTe nanostructures as matrixes. We investigated the effects of several parameters, including the concentration of the HgTe nanostructures, the pH of the buffer, and the concentration of salt, on the performance of this system. When HgTe nanostructures are used as matrixes, [M + H](+) ions were the dominant signals. Relative to other commonly used nanomaterials, HgTe nanostructures provided lower background signals from metal clusters, fewer fragment ions, less interference from alkali-adducted analyte ions, and a higher mass range (up to 150,000 Da). The present approach provides limits of detection for angiotensin I and bovine serum albumin of 200 pM and 14 nM, respectively, with great reproducibility (RSD: <25%). We validated the applicability of this method through the detections of (i) the recombinant proteins that were transformed in E. coli, (ii) the specific complex between bovine serum albumin and l-tryptophan, and (iii) a carbonic anhydrase-acetazolamide complex. Our results suggest that this novel and simple SALDI-MS approach using HgTe nanostructures as matrixes might open several new ways for proteomics and the analysis of drug-protein complexes.

Laser desorption ionization mass spectrometry of protein tryptic digests on nanostructured silicon plates

“…Besides, the improved harnessing of nanomaterial production processes allowed well-controlled inorganic matrix preparation from metals, metal oxides and alloys, under different frameworks. For instance gold [14], iron [15], silver [16], platinum [17], cobalt [18], titanium [19] and other elements [20][21][22][23][24], alone or in combination, were investigated as inorganic matrices by several research groups worldwide. Moreover, disposable ready-to use LDI nanostructured surfaces can be purchased like Nano-Assisted Laser Desorption/Ionization (NALDI™) target plates, constituted by silylated silicon nanowires, which were recently developed for 'matrix-free' LDI analysis of small molecules [25].…”

Citric Acid Capped Iron Oxide Nanoparticles as an Effective MALDI Matrix for Polymers

“…The upper detected mass limits using various NP matrices are generally below 26 kDa for protein samples and 7 kDa for polymers [34,58]. A HgTe NP matrix was reported to increase the upper mass limit for proteins to 150 kDa [59]. A nanostructure initiator development study involving instant release of the trapped initiator molecules (e.g., 14 kDa poly(3,3,3-trifluoropropylmethylsiloxanes) from silicon pores expanded the protein mass detection range to 30 kDa [60].…”

Nanomaterial-Assisted Laser Desorption Ionization for Mass Spectrometry-Based Biomedical Analysis

“…Other inorganic materials are also used to assist LDI, such as graphite [33], carbon nanomaterials [34][35][36], nanodiamonds [37], porous alumina [38], nano-ZnO [39,40], EuF 3 hollow hexagonal nanodisks [41], silver nanoparticles [42], HgTe nanostructures [43], platinum nanoflowers [44], manganese oxide nanoparticles [45], Fe 3 O 4 particles [46], fullerene-derivatized silica [47] and germanium nanodots [48], among others. Recently, we have shown that quantum dots (QDs) of cadmium selenide and cadmium selenide covered with cadmium sulfide can also be used to assist LDI [49].…”