Graphene oxide–metal oxide nanocomposites for on‐target enrichment and analysis of phosphorylated biomolecules

Abstract

The surface of matrix‐assisted laser desorption/ionization mass spectrometry target is modified for improved signal strength and detection of analytes. The developed method includes on‐target enrichment and detection of phosphopeptides/phospholipids using graphene oxide–lanthanide metal oxides (samarium, gadolinium, dysprosium, and erbium) nanocomposites. Enriched phosphopeptides are detected using material enhanced laser desorption/ionization mass spectrometry and phospholipids by laser desorption/ionization‐mass spectrometry. Nanocomposites are prepared using graphene oxide with respective metal salts at high pH. They are characterized for nano‐morphology, chemistry, porosity, composition, crystallinity, and thermal stability. Phosphopeptides enrichment protocol is developed and optimized for tryptic β‐casein digest and that of phospholipids by phosphatidylcholine standard. Statistical analyses of phosphopeptides and phospholipids from milk show overlapping results for gadolinium, dysprosium, and erbium oxide nanocomposites. GO‐Gd2O3 has better enrichment efficiency and application as LDI material. Selectivity for GO‐Dy2O3 is 1:2500, for GO‐Sm2O3 is 1:3500, and 1:4000 for GO‐Gd2O3. GO‐Er2O3 has a sensitivity of 25 fmol, whereas the highest sensitivity is down to 0.5 fmol for GO‐Gd2O3. On‐target enrichment is batch to batch reproducible with a standard deviation of <1, reduced time of enrichment to 10 min, and ease of operation compared to solid‐phase batch extraction. The developed method enriches serum phosphopeptides characteristic of cancer‐related phosphoproteins.

A Graphene-Coated Silicon Wafer Plate Improves the Sensitivity and Reproducibility of MALDI-TOF MS Analysis of Proteins

“…The use of hydroxyl-group-dominated graphite dots produced by electrochemical etching was reported to overcome the limitations of conventional matrices that cause interference in analyses of low-molecular-weight molecules . Nanocomposites prepared using graphene oxide were introduced as LDI matrices to effectively enrich phosphopeptides/phospholipids and assist in the ionization of concentrated phosphorylated biomolecules . However, these approaches are effective only in increasing the sensitivity for low-molecular-weight molecules, and they require LDI to be performed with chemical modification , or in combination with other matrices. , …”

“…19 Nanocomposites prepared using graphene oxide were introduced as LDI matrices to effectively enrich phosphopeptides/phospholipids and assist in the ionization of concentrated phosphorylated biomolecules. 20 However, these approaches are effective only in increasing the sensitivity for low-molecular-weight molecules, and they require LDI to be performed with chemical modification 21,22 or in combination with other matrices. 23,24 Recently, MALDI-TOF MS has been used for screening and diagnostic research in addition to protein identification, and it has become important to accurately analyze targets with defined molecular weights to ensure reliability.…”

In‐situ sorbent formation for the extraction of pesticides from honey

“…However, in recent years, many attempts have been done towards the development of DSPE methods with new sorbents. These studies were mainly focused on the application of synthetic compounds like silicon carbide [17], graphene oxide [18], metal‐organic frameworks [19], cyanopropyl [20], molecularly imprinted polymers [21], coated Fe 3 O 4 nanoparticles [22], etc. It is obvious that synthesis of the sorbents is a time‐consuming approach and in many cases, several steps and different reagents are needed.…”

Titanium dioxide‐functionalized dendritic mesoporous silica nanoparticles for highly selective isolation of phosphoproteins

“…For this purpose, various strategies have been applied for phosphorylated biomolecules separation and enrichment including strong ion-exchange chromatography [6][7][8], immobilized metal ion affinity chromatography (IMAC) [9][10][11][12], and metal oxide affinity chromatography (MOAC) [13][14][15][16]. Among these, MOAC materials have gained increasing popularity due to their excellent structural stability and the reversible chemisorption of phosphate groups on their amphoteric surface with remarkable specificity and less nonspecific binding [17].…”