Evaluation of Three Peptide Immobilization Techniques on a QCM Surface Related to Acetaldehyde Responses in the Gas Phase

Abstract

The quartz-crystal microbalance is a sensitive and universal tool for measuring concentrations of various gases in the air. Biochemical functionalization of the QCM electrode allows a label-free detection of specific molecular interactions with high sensitivity and specificity. In addition, it enables a real-time determination of its kinetic rates and affinity constants. This makes QCM a versatile bioanalytical screening tool for various applications, with surface modifications ranging from the detection of single molecular monolayers to whole cells. Various types of biomaterials, including peptides mapping the binding sites of olfactory receptors, can be deposited as a sensitive element on the surface of the electrodes. One of key ways to ensure the sensitivity and accuracy of the sensor is provided by application of an optimal and repeatable method of immobilization. Therefore, effective sensors operation requires development of an optimal method of deposition. This paper reviews popular techniques (drop-casting, spin-coating, dip-coating) for coating peptides on piezoelectric crystals surface. Peptide (LEKKKKDC-NH2) derived from an aldehyde binding site in the HarmOBP7 protein was synthesized and used as a sensing material for the biosensor. The degree of deposition of the sensitive layer was monitoring by variations in the sensors frequency. The highest mass threshold for QCM measurements for peptides was approximately 16.43 µg·mm−2 for spin coating method. Developed sensor exhibited repeatable response to acetaldehyde. Moreover, responses to toluene was observed to evaluate sensors specificity. Calibration curves of the three sensors showed good determination coefficients (R2 > 0.99) for drop casting and dip coating and 0.97 for the spin-coating method. Sensors sensitivity vs. acetaldehyde were significantly higher for the dip-coating and drop-casting methods and lower for spin-coating one.

Electronic Nose and Its Applications: A Survey

“…Furthermore, the biotoxicity of metallic electrodes caused by some bioactive coating films can be eliminated through employing electrodeless crystal configurations [36] . Additionally, molecularly imprinted polymers (MIPs) [37] , polished gold films [38] , biomimetic peptide-based sensing materials [39] , multi-wall carbon nanotubes [40] , acidized-multiwalled carbon nanotubes [41] and calixarenes [42] can be used in QCM sensors to coat surface layers.…”

Application of QCM in Peptide and Protein-Based Drug Product Development

“…The QCM transducers’ surfaces can be covered with different layers, such as metals, metal alloys, metal oxides [ 11 ], semiconductors, polymers, biomaterials, etc. [ 12 , 13 , 14 ]. The sensitivity of QCMs is about 100 times higher than that of a typical precise analytical balance, thus enabling observation of mass change at a nanogram level (for a typical piezoelectric sensor with 10 MHz frequency, a change in mass of 4.4 ng·cm −2 results in a frequency change of around 1 Hz) [ 15 ], as well as distinguishing single layers or even atomic monolayers [ 16 ].…”

“…Due to the application of selected transduction techniques in chemo- and bio-sensors [ 18 , 19 , 20 , 21 , 22 , 23 ], it is possible to evaluate the deposition degree of particular materials [ 24 ], for instance in the form of self-assembled monolayers (SAM) [ 12 , 25 ], and to analyze gas phase composition [ 14 , 26 , 27 ]. Nowadays, the priority in design and development of QCM analytical platforms is given to naturally occurring compounds, since they are excellent receptors with superior selectivity for the target analytes [ 28 ].…”

“…Nevertheless, the QCM analyses still have some limitations, namely the lack of a standardization method for protein/peptide drug product development studies and a relatively long time of analysis (approximately 1 h). Another important problem with the QCM might be poor reproducibility of layer deposition on the surface of transducer, which can have a massive impact on the measurements with this technology [ 12 , 127 ] and might call for complementary techniques, such as microscopic characterization of obtained surfaces. However, to overcome this problem one can also acquire commercially available sensors [ 128 ].…”

Integrated Multichannel Electrochemical–Quartz Crystal Microbalance Sensors for Liquid Sensing

“…When used as biosensors, it has an added advantage of being a label-free sensor. The typical configuration of QCM is a single element sensor, but multichannel QCM array have also been proposed [7], [8]. QCM arrays can help to minimize effects of variations in environmental parameters such as temperature.…”