In Situ Production of Biofunctionalized Few‐Layer Defect‐Free Microsheets of Graphene

Abstract

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

Controlling the Graphene–Bio Interface: Dispersions in Animal Sera for Enhanced Stability and Reduced Toxicity

“…Direct exfoliation of graphite to graphene in water is achieved by using small organic molecules, 12 amphiphilic stabilizers such as surfactants, 13 proteins, 8,14,15 and carbohydrates. 16 The reagent used for this process (exfoliating agent) should stabilize graphene in water, but it should not be toxic to most biological systems, if the preparations are to be used for biological applications.…”

On‐the‐Spot Immobilization of Quantum Dots, Graphene Oxide, and Proteins via Hydrophobins

“…[ 74 ] Air plasma can be used in surface technology to process glasses, highly oxidizing a few monolayers of the surface and removing organic contaminants. Since Vmh2 in 60% ethanol solution is endowed with positive electrostatic potential (measured by electrophoretic mobility), [ 71 ] negatively charged glass surfaces obtained by air plasma treatment were appropriate to enhance the studied protein binding. Moreover, given that the adhesion energy of the protein layer is dominated by hydrophobic and Coulombic charge interactions, [ 75,76 ] the hydrophobin orientation will determine the effi ciency of immobilization of the interested molecules to the modifi ed surface.…”

“…[ 72 ] The Vmh2 monolayer acts as a bioactive substrate to bind other proteins, which show improved stability and activity when bound on the biohybrid chips. [70][71][72][73] In this work, we propose a fast, highly homogeneous, and effi cient glass functionalization method by spontaneous selfassembling of Vmh2 at liquid-solid interface. In addition, we demonstrate for the fi rst time the immobilization of nanomaterials and proteins via hydrophobins in a microarray fashion, which results to be a time-saving process.…”

“…This Class I HFB has been isolated and studied in our laboratories and used for modifi cation of steel, [ 69,70 ] nanostructured silicon, [ 67 ] and graphene-based materials. [ 71 ] The nanometric layer (≈2.5 nm tick) of Vmh2 has been characterized on different surfaces as well its self-assembled rod-like structures, typically formed by Class I HFBs. [ 72 ] The Vmh2 monolayer acts as a bioactive substrate to bind other proteins, which show improved stability and activity when bound on the biohybrid chips.…”

Characteristics of Graphene Production from Graphite using Plant Extracts

“…또한 최근 들어 약물전달, 암 치료, 생물학적 이미징 등 생물의약분야에 그래핀을 이용하려는 시도가 활발하다 [4]. 현재까지 알려진 그래핀 생산방법은 셀로판테이프법 [5], 화학증착법 [6], 에피택셜법 [7], 화학 계면활성제/유기용매-초음파법 [8][9][10][11], 산화-환원 반응을 이용한 화학적 방법 [12][13][14] Fig. 3.…”