Real-Time Characterization of Fibrinogen Interaction with Modified Titanium Dioxide Film by Quartz Crystal Microbalance with Dissipation

The adsorption of fibrinogen can be used as a quick indicator of surface haemocompatibility because of its prominent role in coagulation and platelet adhesion. In this work the molecular interaction between fibrinogen and a modified titanium oxide surface/platelet has been studied by quartz crystal microbalanee with dissipation （QCM-D） in situ. In order to further characterize the conformation of adsorbed fibrinogen, αC and γ-chain antibody were used to check the orientation and denaturation of fibrinogen on solid surface. QCM-D investiga- tions revealed the fibrinogen have the trend to adsorb on hydropllilic surface in a side-on orientation by positively charged αC domains, which would reduce the exposure of platelet bonding site on γ chain and enable less platelet adhesion and be activated. These obser- vations suggest that certain conformations of adsorbed fibrinogen are less platelet adhesive than others, which opens a possibility for creating a non-platelet adhesive substrates.

Protein adsorption behaviors on chitosan/poly(ε-caprolactone) blend films studied by quartz crystal microbalance with dissipation monitoring(QCM-D)

Chitosan/poly(ε-caprolactone) (PCL) blend films in different mass ratios were prepared using the chitosan/PCL mixture solutions in 80 vol.-% acetic acid by spin coating. Their surface micromorphologies were assessed by atomic force microscopy (AFM). It was found that the micromorphology of chitosan/PCL blend films was in large extent related to the mass ratio of chitosan. 25 wt% chitosan/PCL blend film presented microphase separation. The protein adsorption of bovine serum albumin (BSA) onto chitosan/PCL blend films was investigated by using quartz crystal microbalance with dissipation monitoring (QCM-D) in real time. The results suggested that the amount of adsorbed BSA on the chitosan/PCL blend films decreased with the addition of chitosan, but the structure and viscoelastic properties of the adsorbed BSA layers were greatly affected by the surface micromorphology of chitosan/PCL blend films. BSA absorbed on the 25 wt% chitosan/PCL blend film with microphase separa- tion showed larger adsorption reversibility, and preferred to form a loose, dissipative layer in comparison with those on other chitosan/PCL blend films without microphase separation.

The effect of typical seawater cations on the adhesion of mussel protein Mefp-1 based on dissipative quartz crystal microbalance

Mussels are common anchoring organisms that adhere to the surfaces of various substrates with their byssus.The adhesion of mussel to substrates is contingent upon the presence of mussel foot proteins,of which Mytilus edulis foot protein-1(Mefp-1)has been identified as the most abundant protein.It has been found that lipids are involved in the mussel adhesion process and can facilitate Mefp-1adhesion.In this research,the adhesion behavior of Mefp-1 on various substrate surfaces under the effect of typical seawater cations with or without the presence of lipid were investigated using a quartz crystal microbalance with dissipation(QCM-D).Results indicate that the presence of cations Ca^(2+),Mg^(2+),Na^(+),and K^(+)leads to varying degrees of reduction in the adhesion performance of Mefp-1 on different substrates.The degree of this reduction,however,was much alleviated in the presence of palmitic acid,which is involved in the mussel adhesion process.Therefore,the involvement of palmitic acid is advantageous for mussel protein adhesion to the substrate surface in the marine environment.This study illustrated the significant contribution of palmitic acid to mussel adhesion,which can help to better understand biofouling mechanisms and develop biomimetic adhesive materials.

Research on Friction Properties of Mineral Lubricants in Thin-Film-Lubricating Regime

On the basis of thin film lubrication theory, the influence of fluid film(disordered film), ordered film and adsorbed film on tribological behavior of lubricating oil in thin-film lubrication(TFL) regime was studied. The μ-L(friction coefficient versus load) curves of different oil viscosity and additive dosage were obtained by a high frequency reciprocating test rig and the adsorption capacity of additive on steel surface were measured by QCM-D. Based on the Stribeck curve and thin film lubrication theory model, some conclusions can be drawn up, namely:(1) The μ-L curves and the parameters of L0 and μ0, obtained from the high frequency reciprocating test rig with ball-disc contact, can be used to study tribological behaviors of lubricating oil under TFL conditions.(2) In comparison with the high viscosity base fluid, the lower one can enter into TFL regime under lower load and keeps a lower friction coefficient in TFL regime.(3) The polar molecules in additive formulation produce ordered adsorbed layer on steel surface to reduce friction coefficient. And in TFL regime, the molecule's polarity, layer thickness and saturation degree on steel surface probably can influence lubricant's tribological behaviors between the moving interfaces. Moreover, the further study would be focused on the competitive adsorption of different additives, the formation of dual- and/or tri-molecular adsorption layers, and other aspects.

Impacts of inorganic salts ions on the polar components desorption efficiency from tight sandstone:A molecular dynamics simulation and QCM-D study

Ions in brine significantly affect EOR.However,the mechanism of EOR with different brine is still controversial.By Combining Molecular Dynamics(MD)method and Quartz Crystal Microbalance with Dissipation(QCM-D)technology to analyze ions distribution and the mechanisms in detaching acidic components on the sandstone,an effective method to determine the detaching capacity was established.The results show that detaching capacity is related to ions distribution and hydration capacity.In the oil/brine/rock system,ions far from the rock are favorable for detaching,while ions near the rock are unfavorable for detaching due to ion bridging effect.The hydrogen bond between water and naphthenic acid is key to detaching.Cations strengthen the detaching by forming hydrated ions with water,and the detaching capacity is negatively correlated with hydrated ions radius and positively correlated with the water coordination number.The detaching determination coefficient was established by considering the ions distribution,ions types,and hydration strength,then verified by QCM-D.The brine detaching capacity with different Ca^(2+)/Mg^(2+)ratios was predicted based on MD and detaching determination coefficient,and verified by QCM-D.The optimal Ca^(2+)/Mg^(2+)ratio gave 7:3.This study provides theoretical guidance for targeted regulation of brine composition to improve the recovery of tight sandstone reservoir.

Experimental techniques for quantifying interactions of polymer-coated particles and surfaces: Insights for material design and optimization

Polymer-coated particles and surfaces have widespread applications in various industries ranging from manufacturing to biomedicine.A better understanding of the stability mechanisms underlying these coatings can inspire the design of novel polymer structures and help tune their functions.This can be achieved by quantifying the particle-particle and particle-surface interactions.This paper reviews several common experimental techniques utilized to measure the interactions between polymer-coated particles and surfaces quantitatively.These techniques include atomic force microscopy(AFM),total internal reflection microscopy(TIRM),optical tweezers(OT),and quartz crystal microbalance with dissipation monitoring(QCM-D).The examples of each measuring technique were categorized based on the types of polymer coatings and their associated factors.Additionally,this review demonstrates experimental measurements of interactions involving biological objects.By understanding the fundamental particle-particle and particle-surface interactions,researchers can gain valuable insights to guide the design and functional optimization of polymer-based materials and systems across various applications.

ammonium salt as a collector and its adsorption mechanism

A novel quaternary ammonium salt collector,LH-01,was employed for the reverse cationic flotation of a magnesium-depleted concentrate(P2O5 grade of 19.72wt%,SiO2 content of 44.26wt%).We achieved an outstanding phosphate concentrate with a P2O5 grade of 35.16wt%,a SiO2 content of 6.06wt%,and a P2O5 recovery of 75.88%.This process was accomplished through two sequential reverse cationic flotation processes designed for quartz removal.Importantly,the quartz removal by LH-01 reached 94.17%,far superior to that by dodecyltrimethylammonium chloride,achieving highly selective separation of quartz and apatite.To understand the adsorption mechanism and kinetics of the collector LH-01 on quartz and apatite surfaces,various techniques,such as quartz crystal microbalance with dissipation,atomic force microscopy,and X-ray photoelectron spectroscopy,were employed.Results revealed that the adsorption layer of LH-01 on the apatite surface was thin and rigid,with a significantly lower hydrophobic effect than that of the viscoelastic multiple adsorption layer formed by LH-01 on the quartz surface.This disparity was identified as the primary factor contributing to the selective flotation separation of apatite and quartz.Moreover,the adsorption of LH-01 on the quartz surface was the result of multiple forces,including electrostatic adsorption,multiple-hydrogen-bond adsorption,and intermolecular hydrophobic association.

Self-assembly of anisotropic tobacco mosaic virus nanoparticles on gold substrate

A facile approach to assembled virus film with tunable structure is presented.Rod-like tobacco mosaic virus (TMV) was selected as the prototype in this study for its anisotropic structural feature.TMV can either "lie down" or "stand up" on gold substrate by tuning the solution pH.A quartz crystal microbalance with dissipation monitoring was used to monitor the pH-dependent self-assembly behavior of TMV nanoparticles,and atomic force microscopy and single molecule force spectroscopy further confirmed the different assembly structures.