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
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 aS1-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.
KeywordsBiomarker Magnetic nanoparticles MALDI-TOF Milk Protein corona
This work was supported by the University of Padua (Italy), grant PRAT 2015 (progetti di Ateneo) n. CPDA159850, “Assegni di Ricerca Junior” 2014 n. CPDR148959, and by the CARIPARO Foundation.
Compliance with ethical standards
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. According to the Directive 2010/63/EU of the European Parliament and the D.L. 26/2014 of the Italian Government, no ethical approval is needed for carrying out experimental research on milk samples coming from cows under physiological lactation.
Conflict of interest
The authors declare that they have no conflict of interest.
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