Biological interfacing of graphene has become crucial to improve its biocompatibility,\ud
dispersability, and selectivity. However, biofunctionalization of\ud
graphene without yielding defects in its sp 2 -carbon lattice is a major challenge.\ud
Here, a process is set out for biofunctionalized defect-free graphene\ud
synthesis through the liquid phase ultrasonic exfoliation of raw graphitic\ud
material assisted by the self-assembling fungal hydrophobin Vmh2. This\ud
protein (extracted from the edible fungus Pleurotus ostreatus ) is endowed\ud
with peculiar physicochemical properties, exceptional stability, and versatility.\ud
The unique properties of Vmh2 and, above all, its superior hydrophobicity,\ud
and stability allow us to obtain a highly concentrated (≈440–510 μg mL −1 ) and\ud
stable exfoliated material ( ζ -potential, +40/+70 mV). In addition controlled\ud
centrifugation enables the selection of biofunctionalized few-layer defect-free\ud
micrographene fl akes, as assessed by Raman spectroscopy, atomic force\ud
microscopy, scanning electron microscopy, and electrophoretic mobility.\ud
This biofunctionalized product represents a high value added material for\ud
the emerging applications of graphene in the biotechnological fi eld such as\ud
sensing, nanomedicine, and bioelectronics technologies
Class I hydrophobin Vmh2, a peculiar surface active and versatile fungal\ud
protein, is known to self-assemble into chemically stable amphiphilic fi lms,\ud
to be able to change wettability of surfaces, and to strongly adsorb other\ud
proteins. Herein, a fast, highly homogeneous and effi cient glass functionalization\ud
by spontaneous self-assembling of Vmh2 at liquid–solid interfaces is\ud
achieved (in 2 min). The Vmh2-coated glass slides are proven to immobilize\ud
not only proteins but also nanomaterials such as graphene oxide (GO) and\ud
quantum dots (QDs). As models, bovine serum albumin labeled with Alexa\ud
555 fl uorophore, anti-immunoglobulin G antibodies, and cadmium telluride\ud
QDs are patterned in a microarray fashion in order to demonstrate functionality,\ud
reproducibility, and versatility of the proposed substrate. Additionally, a\ud
GO layer is effectively and homogeneously self-assembled onto the studied\ud
functionalized surface. This approach offers a quick and simple alternative to\ud
immobilize nanomaterials and proteins, which is appealing for new bioanalytical\ud
and nanobioenabled applications
The development of efficient and rapid methods for the identification with high sequence coverage of proteins is one of the most important goals of proteomic strategies today. The on-plate digestion of proteins is a very attractive approach, due to the possibility of coupling immobilized-enzymatic digestion with direct matrix-assisted laser desorption/ionization (MALDI)-time of flight (TOF)-mass spectrometry (MS) analysis. The crucial step in the development of on-plate immobilization is however the functionalization of the solid surface. Fungal self-assembling proteins, the hydrophobins, are able to efficiently functionalize surfaces. We have recently shown that such modified plates are able to absorb either peptides or proteins and are amenable to MALDI-TOF-MS analysis. In this paper, the hydrophobin-coated MALDI sample plates were exploited as a lab-on-plate for noncovalent immobilization of enzymes commonly used in protein identification/characterization, such as trypsin, V8 protease, PNGaseF, and alkaline phosphatase. Rapid and efficient on-plate reactions were performed to achieve high sequence coverage of model proteins, particularly when performing multiple enzyme digestions. The possibility of exploiting this direct on-plate MALDI-TOF/TOF analysis has been investigated on model proteins and, as proof of concept, on entire whey milk proteome.
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