To Explore The Effect And Mechanism Of Fatty Acid On The Adhesion Of Mussel Foot Protein Based On Dissipative Quartz Crystal Microbalance

Mussels,a semi-sessile-living attachment animal,are considered as model organisms for the study of gradient functional materials and bioadhesion in the marine environments.Research on the adhesion mechanism of mussels has greatly facilitated the development and application of biomimetic/underwater adhesion materials.In nature,mussels rely on byssus to firmly adhere themselves to a variety of substrates.The strong underwater adhesion of mussels is mainly related to the mussel foot protein(Mfp)in the byssus.3,4-Dihydroxyphenylalanine(DOPA)in Mfp can bind to substrates through hydrogen bonding,metal chelation,covalent bonding,and hydrophobic interactions,etc.Recent studies have found that lipids are involved in mussel bioadhesion as an important component,but there are few studies and data on the role and mechanism of lipids in the underwater adhesion of mussels.Therefore,in this study,a novel interface interaction analysis tool,the Quartz Crystal Microbalance with Dissipation(QCM-D),was used to study the role and mechanism of fatty acids in the adhesion process of Mfp.This provides a new insight for the development of efficient underwater adhesion materials and marine antifouling research.The main research contents are as follows:(1)Au was used as the adhesion substrate of mussel foot protein(Mefp-1),and the solid-liquid interface of mussel bioadhesion was simulated by QCM-D to monitor the dynamic adsorption and binding of Mefp-1 on Au surface in the buffer environment in real time.The QCM-D signal was analyzed according to the rigid adsorption model,and the results showed that Mefp-1 could be adsorbed and bound to the Au surface in a short time in the buffer environment.The study of adhesion mechanism showed that the reason why Mefp-1 could adhere to Au surface in buffer environment was mainly through the interaction between DOPA and Au.Using palmitic acid as the lipid source,the effect of fatty acid on the adhesion of Mefp-1 on Au surface and its mechanism were explored by QCM-D.The results of viscoelastic adsorption model analysis showed that palmitic acid could promote the binding of Mefp-1 to the Au surface in the buffer environment,its mechanism is mainly to promote the binding of a large amount of Mefp-1 to Au by changing the hydration environment around the Au surface.And with the increase of palmitic acid concentration,palmitic acid may synergize with Mefp-1 to further promote the adhesion of Mefp-1 to the Au surface.(2)In order to simulate the natural environment substrate for mussels to attach,this study used Si O₂as the Mefp-1 adhesion substrate,and analyzed the adhesion and mechanism of Mefp-1 on Si O₂surface in buffer environment by QCM-D.The results show that it is more difficult for Mefp-1 to adsorb and bind to the surface of polar hydrophilic Si O₂substrate in the buffer environment,but there is still a small amount of Mefp-1 that can break through the barrier of the stable hydration layer and bind to the surface of Si O₂through DOPA.Then QCM-D was used to explore the effect of fatty acid on the adhesion of Mefp-1 on Si O₂surface and its mechanism.The results show that palmitic acid can also promote the adsorption and binding of Mefp-1 to the polar hydrophilic Si O₂substrate.And with the increase of palmitic acid concentration,this effect of promoting Mefp-1 binding was stronger.Interestingly,low concentrations of palmitic acid can change the hydration environment of the polar hydrophilic Si O₂surface or synergize with Mep-1 to promote the adhesion and binding of Mefp-1.But for Au substrate,the synergistic effect of this low concentration palmitic acid-Mep-1 is almost no.Accordingly,this study proposes a novel model of fatty acid-mediated underwater adhesion of mussel foot proteins.(3)In order to study the universality of fatty acid promoting Mfp adhesion,mussels from the deep hydrothermal region of the Indian Ocean were used as research objects.The internal and external morphological features of byssus were observed microscopically and macroscopically by optical microscope and scanning electron microscope(SEM).Then the mechanical properties were tested by electronic tensile testing machine.Finally,combined with amino acid analysis and Fourier transform infrared spectroscopy(FT-IR),the internal components and structures of mussel byssus in the hydrothermal region were detected.Combined with multiple characterization analyses,the study shows that the structure,composition and mechanical properties of the deep-sea mussel byssus in the Indian Ocean hydrothermal area are obviously more suitable for their attachment life in the deep ocean.