Abstract
The interaction between graphene oxide (GO) and lysozyme (LYZ) in aqueous solution was investigated for GO specific surface area determination and for the thermodynamic description of the process. It was experimentally proved that LYZ is a much better adsorbate than the most common methylene blue, allowing the determination of genuine GO surface area. Our fluorescence spectroscopy results indicate that LYZ molecules interact with GO at high- and low-affinity sites depending on the surface coverage, reflecting the protein mono- and multilayer formation, respectively. The lack of the secondary structure changes confirms LYZ usability as a model adsorbate. The calculated values of thermodynamic parameters (Δ(ΔH0) = −195.0 kJ/mol and Δ(ΔS0) = −621.3 J/molK) indicate that the interactions are exothermic, enthalpy-driven. All the reported results reveal the physical nature of the LYZ–GO interaction at the studied concentration ratios.
Highlights
Graphene oxide (GO) is one of the most studied carbonaceous materials owing to its exceptional physicochemical and biological features
We aimed to prove the possibility of proper, genuine GO surface measurements using the small, rigid protein lysozyme as the adsorbate
GO was synthesized by a modified Hummers method[5,6] and described previously.[7−9] Briefly, 50 mL of concentrated H2SO4 was added to graphite flakes (0.175 g)
Summary
Graphene oxide (GO) is one of the most studied carbonaceous materials owing to its exceptional physicochemical and biological features. GO has been commonly referred to for biomedical applications, including but not limited to biosensing, drug delivery, and imaging, as well as for the control of stem cell differentiation. The fundamental interactions between the GO surface and biomolecules, active compounds, drugs, and cells strongly influence the biological pathways; the mechanism of such influence remains unknown.[1,2] The drug and gene delivery approach relies on the successful adsorption of the plethora of molecules on the surface of GO structure, offering high potential as a delivery carrier.[1] graphene-based materials remain highly successful in the cell and tissue engineering field for the regeneration of various tissues. The most exciting findings include nerve, cartilage, skeletal muscle, cardiac tissue, and skin regeneration, as well as GO effects on the induced pluripotent stem cell cytophysiology.[3] some challenging issues of GO application, such as long-term toxicity or biodegradability, have impeded its widespread access to clinics
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