Qsense dfind

Lysozyme adsorption on the gold surface was also carried out using the QCM-D E1 Q-Sense, Biolin Scientific, Espoo, Finland with a flow module. The measurement sequence and conditions were the same as for MP-SPR. The QCM-D method allows determining both the change in the mass of adsorbed molecules and the adsorption process’s reversibility/irreversibility. During the measurements, two parameters were monitored: the change in the resonance frequency (ΔF) and the change in energy dissipation (ΔD). For thin, homogeneous, and rigid layers, according to the Sauerbrey equation, the resonance frequency is proportional to the mass adsorbed on the surface of the QCM-D sensor (Г_QCM-D). In the case of layers with viscoelastic properties, the adsorbed mass is determined using the Voigt model. This model’s calculations were performed using the QSense DFind, Biolin Scientific, Espoo, Finland program based on the measurement results for 3–11 frequency overtones. The established constant parameters were: the solvent density-998 kg/m³ for 0.01 M and 1003 kg/m³; and the protein layer density-1113 kg/m³ for 0.01 M and 1118 kg/m³ for 0.15 M, respectively. The model fit was applied to the time corresponding to lysozyme adsorption. The association, dissociation, and affinity coefficients were calculated using TraceDrawer, Ridgeview Instruments AB, Ridgeview Instruments AB, Uppsala, Sweden software.

Enzyme storage was studied with a quartz
crystal microbalance (Q-Sense E4 instrument, Biolin Scientific) on
BCP₄₀ mesoporous films prepared onto silica-coated QCM
sensors (5 MHz 14 mm Cr/Au/SiO₂, Quartz PRO) with an active
area of 0.79 cm². In a continuous measurement, lysozyme
adsorption was induced by pumping 2 mg mL^–1 of lysozyme
in 0.1 M PBS buffer (pH 7.3) into the QCM chamber, and subsequent
lysozyme desorption was induced by pumping PBS buffer into the chamber.
Lysozyme and PBS were pumped into the QCM chamber at a flow rate of
30 μL min^–1. Frequency analysis, conversion
to the Sauerbrey mass using the composite Sauerbrey of the frequency
harmonics f₃, f₅, f₇, f₉, f₁₁, and f₁₃, and
validation of the model were performed with the software QSense Dfind
(Biolin Scientific).

Enzyme immobilization into
the porous aluminosilicate coating was studied with a quartz crystal
microbalance with dissipation monitoring (Q-Sense E4 instrument, Biolin
Scientific) using a previously coated QCM sensor (5 MHz, 14 mm Cr/Au/SiO₂, 0.79 cm² active area, Quartz PRO). Solutions
were pumped at a flow rate of 30 μL min^–1 into
the QCM chamber. QCM analysis (frequency and dissipation) of the harmonics f3, f5, f7, f9, f11, and f13 was performed with
the software QSense Dfind (Biolin Scientific).