Analysis of hard protein corona composition on selective iron oxide nanoparticles by MALDI-TOF mass spectrometry: identification and amplification of a hidden mastitis biomarker in milk proteome

Abstract

Surface active maghemite nanoparticles (SAMNs) are able to recognize and bind selected proteins in complex biological systems, forming a hard protein corona. Upon a 5-min incubation in bovine whey from mastitis-affected cows, a significant enrichment of a single peptide characterized by a molecular weight at 4338 Da originated from the proteolysis of a-casein was observed. Notably, among the large number of macromolecules in bovine milk, the detection of this specific peptide can hardly be accomplished by conventional analytical techniques. The selective formation of a stable binding between the peptide and SAMNs is due to the stability gained by adsorption-induced surface restructuration of the nanomaterial. We attributed the surface recognition properties of SAMNs to the chelation of iron(III) sites on their surface by sterically compatible carboxylic groups of the peptide. The specific peptide recognition by SAMNs allows its easy determination by MALDI-TOF mass spectrometry, and a threshold value of its normalized peak intensity was identified by a logistic regression approach and suggested for the rapid diagnosis of the pathology. Thus, the present report proposes the analysis of hard protein corona on nanomaterials as a perspective for developing fast analytical procedures for the diagnosis of mastitis in cows. Moreover, the huge simplification of proteome complexity by exploiting the selectivity derived by the peculiar SAMN surface topography, due to the iron(III) distribution pattern, could be of general interest, leading to competitive applications in food science and in biomedicine, allowing the rapid determination of hidden biomarkers by a cutting edge diagnostic strategy. Graphical abstract The topography of iron(III) sites on surface active maghemite nanoparticles (SAMNs) allows the recognition of sterically compatible carboxylic groups on proteins and peptides in complex biological matrixes. The analysis of hard protein corona on SAMNs led to the determination of a biomarker for cow mastitis in milk by MALDI-TOF mass spectrometry.

The surface reactivity of iron oxide nanoparticles as a potential hazard for aquatic environments: A study on Daphnia magna adults and embryos

“…Thus, SAMNs exerted a detrimental effect only when the membrane was still present. Possibly, surface under-coordinated iron sites of SAMNs specifically interacted with proteins and/or phospholipids coating the outer shell of the egg membrane 88 – 90 . These macromolecules are both susceptible to interact with SAMNs as they present a proclivity toward Fe 3+ chelation 40 .…”

Nanoparticle Characterization: What to Measure?

“…MS is also unique in providing information on the functionalization layer grafted on the surface of nanoparticles . Furthermore, MS has often been applied in the investigation of interactions between nanoparticles and biomolecules after exposure to biological fluids to identify and quantify the composition of complex protein coronas on the nanoparticle surface . Finally, the ability of MS to ionize and investigate soft materials, such as tissues, has rendered this technique invaluable in studying the biodistribution and uptake of nanoparticles within different organs upon administration of nanoparticle solutions for toxicology studies …”

Liquid Atmospheric Pressure Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Adds Enhanced Functionalities to MALDI MS Profiling for Disease Diagnostics

“…This peptide has been reported by other studies but has not been attributed to the action of a known endogenous (or exogenous) enzyme. 20,28,29 The identity of this unknown enzyme could be important for targeted mastitis detection. The second ion at m / z 729 can be derived from the proteolysis of α-s 1 -casein by cathepsin B or D, producing a peptide composed of amino acids R 1 -F 24 .…”