Acoustic network analysis as a novel technique for studying protein adsorption and denaturation at surfaces

Abstract

The understanding of the interaction of proteins with solid surfaces1-3 is important in the development of implantable medical devices, biotechnology, and biosensors. Some of the more common techniques for studying proteins at an interface include radiolabeling and fluorescent tagging; spectroscopic methods such as ellipsometry, total internal reflectance fluorescence (TIRF), and attenuated total reflectance Fouriertransform infrared spectroscopy (ATR-FTIR); and surface characterization methods such as X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). These techniques have been thoroughly reviewed.* 1 They provide information either on the amount and rate of adsorption of proteins or on the conformation of the adsorbate.However, protein adsorption and the orientation of the adsorbed molecules involves a large number of time-dependent dynamic phenomena where conformational changes can occur during the adsorption process. Few of the above techniques are capable of monitoring in situ adsorption and providing evidence of conformational effects in real time. In this preliminary report, we demonstrate that the response of the thickness-shear mode (TSM) acoustic wave sensor can be correlated to interfacial processes involving protein adsorption and denaturation at surfaces.A number of studies have employed the so-called quartz crystal microbalance technique to determine the amount of adsorbed protein.4-7 The detection scheme is based on the changes of the oscillating frequency of piezoelectric devices upon mass loading.8 The mass-frequency relationship is describe by the Sauerbrey equation 2/02Am A(pqMq)1/2

Immunosensing Platforms Using Spontaneously Adsorbed Antibody Fragments on Gold

“…The absorbance decreases in both cases are attributed to the specific binding of the labeled IgG to each of the antigenic surfaces. We note that the shapes of both curves, which are indicative of multiple-step adsorption processes, 32,33 are representative of repeated trials performed in each system and are similar to those previous reported. [32][33][34][35] To confirm that the absorbance decreases result from the specific binding of the labeled IgG to the modified gold surfaces and not from nonspecific adsorption onto any other portion of the sample or the TLC, several control experiments were conducted.…”

“…We note that the shapes of both curves, which are indicative of multiple-step adsorption processes, 32,33 are representative of repeated trials performed in each system and are similar to those previous reported. [32][33][34][35] To confirm that the absorbance decreases result from the specific binding of the labeled IgG to the modified gold surfaces and not from nonspecific adsorption onto any other portion of the sample or the TLC, several control experiments were conducted. Figure 3C presents the results of one such an experiment in which a solution of FITC-conjugated goat anti-rabbit was injected into the TLC containing a surface modified with whole molecule goat IgG.…”

Quantitative measurement of p53-p53 antibody interactions by quartz crystal microbalance: A modelsystem for immunochemical calibration

“…Curiously, the steepest slopes were recorded for p53 adsorption, followed by the anti-p53 IgG and goat anti-IgG (Figure 2(b)). Several models were considered to explain R/F ratio variation during protein adsorption and include protein conformational transition after adsorption [16,17], changes in the protein film hydration [9] and protein intermolecular interactions [18]. Our data is consistent with protein reorientation and conformational changes due to formation of the amide (p53) and antibody antigen bonds.…”

Estimation of Kinetics Parameters for the Adsorption of Human Serum Albumin onto Hydroxyapatite-modified Silver Electrodes by Piezoelectric Quartz Crystal Impedance Analysis

“…A kind of piezoelectric quartz crystal (PQC) technique, piezoelectric quartz crystal impedance (PQCI) analysis, is an excellent method for real-time monitoring of crystal resonance performance and for providing multidimensional information reflecting physical and/or chemical properties of the studied system. [11][12][13] The PQC method was applied to study proteins in several fields, such as BSA adsorption, 11,14 protein denaturation 15 and fibrinogen adsorption. 16 But, to the best of our knowledge, it has not been applied to study adsorption of HSA on HAP modified electrode.…”