Interfacial adsorption dynamics of solid lipid particles at oil/water interfaces through QCM-D technique

‘Prothrombinase induced Clotting Time’ (PiCT) has potential to detect all anticoagulants in clinics. In the present study, PiCT has been used as a tool for anticoagulant detection in human plasma on quartz crystal microbalance with dissipation (QCM-D) technique. QCM-D technique enables monitoring of PiCT point, total coagulation and fibrinogen concentration from frequency and dissipation curves in single set of measurements. This is impossible on mechanical coagulometer (which is considered as 'gold standard') technique, and it cannot yield coagulation and fibrinogen concentration from a single set of measurements. It requires additional Clauss method or modified Clauss method to calculate fibrinogen by employing different reagents and experimental setups. Additionally, the present report utilizes the lowest sample volume (and each reagent volume) consumptions of 1.66 µL. The sample/reagent volume consumption of 1.66 µL on QCM-D is 30 times lower in comparison with mechanical coagulometer’s that uses 50 µL for laboratory experiments for PiCT. This element is crucial for application of spot test via QCM-D in laboratory and clinics for Point of Care (POC) settings. Different doses of anticoagulant in 20 human plasma samples on QCM-D technique have been studied and compared in parallel to ‘gold standard’. PiCT on QCM-D technique yielded precise and accurate data. Additionally, both techniques produced % RSD values between 3 and 8.5 with slight fluctuations on both sides for PiCT points. The %RSD data for both techniques has lower variability for danaparoid. Furthermore, QCM-D technique enables monitoring of substantial fibrinogen concentrations (i.e. 1 - 6 g/L) with outstanding R2 value of 0.99 on the calibration curve. PiCT-QCM-D technique proved superior at all concentrations of fibrinogen in standard reference plasma for PiCT range (precision) on comparing to that of 'gold standard'.

QCM-D studies of attachment and differential spreading of pre-osteoblastic cells on Ta and Cr surfaces

Chapter 7.2 - Application of a Quartz Crystal Microbalance with Dissipation for In Situ Monitoring of Interfacial Phenomena between Bioceramics and Cells

Monitoring cell adhesion on tantalum and oxidised polystyrene using a quartz crystal microbalance with dissipation

Thrombin is the central enzyme in the coagulation cascade. Recently, modern technologies for thrombin generation measurement have shown a multidisciplinary interest in methods and assays. This is first report to recognize and optimize for human plasma application of 'thrombin time' (TT) assay for quartz crystal microbalance with dissipation (QCM-D) technique. QCM-D technique has been studied comparatively with mechanical coagulometer (which is regarded as 'gold standard' for coagulation assays). The optimized protocol for TT has been applied for plasma samples (n=54) on both platforms. Thrombin times (TTs) on QCM-D platform versus those of 'gold standard' yielded a promising correlation line with R2 value of 0.86. For TT assay, QCM-D platform proved superior as compared to 'gold standard' platform due to following four edges. Firstly, QCM-D platform provides whole kinetic information, including monitoring of total coagulation on its measurement curve. 'Gold standard' cannot yield this information because it picks one point during coagulation. Secondly, TTs on QCM-D platform are 30% shorter as compared to those of 'gold standard'. Thirdly, TTs on QCM-D technique produced 16% lower %RSD demonstrating lower variability. Lastly, a historical lowest sample volume consumption of 2.50 µl has been applied on QCM-D platform. ‘Gold standard’ employs 40 times greater sample volume consumption for laboratory experiments of TT. Additionally, 40 times lower reagent volume consumption has been employed on QCM-D platform in comparison to its counterpart’s. These advantageous features are substantial support for point of care (POC) settings for TT assay via QCM-D technique.

Mucoadhesion vs mucus permeability of thiolated chitosan polymers and their resulting nanoparticles using a quartz crystal microbalance with dissipation (QCM-D)

Understanding the interactions between enzymes and substrates and the property changes of the substrates during the process is vital for efficiently producing fuels and chemicals from lignocellulosic biomass. In this manuscript, quartz crystal microbalance with dissipation (QCM-D) technique was employed as a tool to investigate the adsorption and hydrolysis behaviors of four fungal cellulases (Trichoderma reesei, Trichoderma viride, Aspergillus sp. and Aspergillus niger) on the substrate of nanofibrillar cellulose (NFC) film. The characterization of the cellulose films before and after enzymatic treatment was represented by atomic force microscopy. The results showed that four cellulases behaved quite differently. The cellulases from T. reesei and T. viride adsorbed onto NFC films and then the hydrolysis was carried out; and their trends represented by different overtones were similar and consistent. The cellulase from Aspergillus sp. adsorbed on the substrate to form a quite compact layer since substantial frequency changed with little dissipation variation. In term of the cellulase from A. niger, its frequency and dissipation overtones exhibited diverged behaviors. After viscoelastic modeling for cellulases except for Aspergillus sp using the multi-overtone data provided by QCM-D technique, the film properties of NFC film and adlayer were extracted and they could help to understand the interactions between cellulases and substrates.

Enhanced bioaccessibility of curcumin in Pickering emulsions stabilized by solid lipid particles

Wettability is an indispensable parameter in multiphase flow due to its profound effect in fluid phase distribution and flow properties in the oil reservoirs. One approach of unravelling the enigma associated with wettability characterization is to investigate oil adhesion onto reservoir rock surface during crude oil accumulation. This was accomplished using Quartz Crystal Microbalance with Dissipation (QCM-D) device. The QCM-D is a microbalance device that hinges on the changes in the frequency of a resonating crystal due to changes in the mass on sensor surface, precipitation, adsorption and desorption. However, this technique was confronted with numerous challenges during its early try-out. The objective of this study is to enumerate these challenges and how they were resolved. The piston-cell, valves, flow-lines and most of the experimental set-up were made from stainless steel. Hence, the high temperature coupled with high salinity brine resulted in the formation and deposition of corroded materials on the sensor. Due to the high sensitivity of the QCM-D technique, these corrosion deposits were detected via the high attenuation of the frequency signal as time elapsed during Formation Water (FW) injection. The second challenge was related to the dissolution of the thin sensor coatings (sensor etching) depicted by the relatively high increase in frequency signal with negligible changes in Dissipation (D). The third challenge was related to the trapping of fluids such as Stock Tank Oil (STO) inside the flow-cell. Finally, salt precipitation resulting from temperature variation during the initial experimental set-up was also observed. To resolve the corrosion challenge, all the stainless-steel components in the experimental set-up were replaced with titanium and non-metallic component such as peek materials. The sensor etching was also averted by injecting the brine through a packed column filled with similar mineral as the coatings on the sensor to attain equilibrium prior to injecting it onto the sensor. Geochemical simulation of the sensor etching was also confirmed using the geochemical simulator PHREEQ-C. Furthermore, the trapping of fluids inside the flow-cell was overcome by rotating the flow-cell to optimize the fluid displacement via capitalizing on their density contrast. Finally, the salt precipitation was avoided by conducting the experiment in a constant temperature experimental set-up. The QCM-D technique can be employed to estimate wettability by evaluating the tendency of the various minerals to adhere oil. The beauty of the QCM-D technique is that the surface interactions can be monitored on a real-time.

We have developed an instrument for surface interaction studies, which combines a newly invented four detector optical reflectometry setup with quartz crystal microbalance with dissipation (QCM-D) monitoring. The design is such that data from both techniques can be obtained simultaneously on the same sensor surface, with the same signal-to-noise ratio and time resolution, as for the individual techniques. In addition, synchronized information about structural transformations, molecular mass, and the hydration of thin films on solid surfaces can be obtained on the same specimen, as validated by monitoring the formation of supported lipid bilayers on a silica-coated QCM sensor surface. We emphasize that the optical (molecular) mass can be separated from the acoustic mass including hydrodynamically coupled solvent, which means, in turn, that the amount of solvent sensed by the QCM-D technique can be dynamically resolved during adsorption processes. In addition, the advantage/necessity to use four, compared to two, detector reflectometry is emphasized.

Activated partial thromboplastin time (aPTT) assay for whole blood on quartz crystal microbalance with dissipation (QCM-D) platform has been recognized for the first time. QCM-D platform is studied in parallel with ‘gold standard’ mechanical coagulometer in the perspective of anticoagulant bio-sensing. In this report, the lowest sample volume application of 1.66 µL of human whole blood for aPTT has been demonstrated. Mechanical coagulomter uses 60 times higher whole blood (and each reagent) volume application of 100 µL for aPTT laboratory experiments. This study is important in the terms of its robustness due to direct whole blood method and its cost-effectiveness due to lowest sample (and reagents) volume application. This could be fundamental support for spot test application by employing QCM-D in laboratory and sergry. Anticoagulant doses in 20 blood samples have been measured on QCM-D platform in comparison to ‘gold standard’. Each technique yielded relative standard deviation values between 7 and 15 depending on different doses of anticoagulant. Furthermore, QCM-D technique is advantageous over 'gold standard’ for additional monitoring of the whole kinetics of coagulation. It displays total coagulation recognition from frequency and dissipation shifts, which is impossible on 'gold standard’.

Measurements of hemostasis parameters such as Prothrombin time (PT) are substantial in various clinical cases of extensive surgery, dialysis or innate hemostasis disorders. This is the first study of recognition of PT assay for human plasma on quartz crystal microbalance with dissipation (QCM-D) platform. QCM-D technique has been compared in parallel with ‘gold standard’ mechanical coagulometer in the terms of anticoagulant monitoring in 20 plasma samples. In this report the shortest sample volume consumption of 2.66 µl of human plasma for PT has been demonstrated on QCM-D platform. This also demonstrates the shortest reagent (thromborel) volume consumption employed ever for PT. 'Gold standard' employs 38 folds higher plasma as well as reagent volume consumption. Additionally, QCM-D technique proved superior to 'gold standard’ for monitoring of the whole process of plasma coagulation kinetics. It yielded total coagulation information from frequency and dissipation shifts, which are impossible on 'gold standard’. Furthermore, QCM-D platform offers the calculation of fibrinogen concentration along with PT and total coagulation monitoring in single set of measurements. Fibrinogen concentration can be calculated from calibration curves having R2 values of 0.99. This is promising support for Point of Care (POC) settings in the perspective that it covers the extreme range of fibrinogen from 1.0 to 6 g/L. PT based QCM-D platform for plasma application proved better alternative to that of 'gold standard' and it paves the path towards routine laboratory method.

In this work, we have identified key parameters for controlling the surface density of ferritin on metal oxides and observed a conformational change of the protein shell of ferritin occurring exclusively at pH 4. The quartz crystal microbalance with dissipation (QCM-D) monitoring technique was used to examine protein adsorption on gold and Ti-, Si-, Ta-, Al-, and Nb-oxide surfaces. A comparative study of the adsorption to Ti-oxide was made using atomic force microscopy (AFM). The surface density of ferritin was controlled by a variation in the solution pH (from 2 to 8) and the isoelectric point (Ip) of the surface. On the basis of these findings, clear trends in the effect of electrostatic interactions between the ferritin proteins and between ferritin and the surface were found, making it possible to tune the surface density of ferritin through the choice of solution pH and the Ip of the surface. Furthermore, the influence of the pH on the viscoelastic properties of the adsorbed ferritin layer was examined using QCM-D. Conformational changes of the protein shell of ferritin were found to occur at pH 4, which is close to the Ip of ferritin (4.6), but not for lower or higher values of the pH. This conformational change of ferritin was seen clearly in dissipation per frequency value obtained from the QCM-D technique.

Thermoresponsive cell-culture polystyrene (PS) surfaces that are grafted with poly(N-isopropylacrylamide) (PIPAAm) facilitate the cultivation of cells at 37 °C and the detachment of cultured cells as a sheet with an underlying extracellular matrix (ECM) by reducing the temperature. However, the ECM and cell detachment mechanisms are still unclear because the detachment of cells from thermoresponsive surfaces is governed by complex interactions among the cells/ECM/surface. To explore the dynamic behavior of serum protein adsorption/desorption, thermoresponsive surfaces that correspond to thermoresponsive tissue-culture PS dishes were formed on sensor chips for quartz crystal microbalance with dissipation (QCM-D) measurements. X-ray photoelectron spectroscopy (XPS) measurements and temperature-dependent frequency and dissipation shifts, Δf and ΔD, using QCM-D revealed that the thermoresponsive polymers were successfully grafted onto oxidized, thin PS films on the surfaces of the sensor chips. Increased amounts of adsorbed bovine serum albumin (BSA) and fibronectin (FN) were observed on the thermoresponsive polymer-grafted surfaces at 37 °C when compared with those at 20 °C because of enhanced hydrophobic interactions with the hydrophobic, thermoresponsive surface. While the calculated masses of adsorbed BSA and FN using QCM-D were 3–5 times more than those that were obtained from radiolabeling, the values were utilized for relative comparisons among the same substrate. More importantly, the thermoresponsive, dynamic behavior of serum protein adsorption/desorption was monitored using the QCM-D technique. Observations of this dynamic behavior revealed that the BSA and FN that were adsorbed at 37 °C remained on both surfaces after decreasing the temperature to 20 °C.

In recent years, modern technologies and devices for coagulation monitoring have demonstrated a multidisciplinary interest in assays and methods. Devices and equipment for point-of-care (POC) coagulation monitoring of whole blood or plasma could eliminate fundamental deficiencies of routine coagulation assays and tests. Quartz Crystal Microbalance with dissipation (QCM-D) is an emerging powerful biomedical device, and it has an outstanding potential in this perspective. This is 'first critical review' article' that focuses the applications of coagulation assays on QCM-D technique, and it covers the substantial scientific efforts from 2011 to January 2016. This article could provide baselines for coagulation assays on QCM-D technology for the future perspectives, ultra-refining the POC settings for laboratory and clinical methods levels in worldwide and far beyond.