Study On QCM Biochip Modified With Polyetherimide Surface

Quartz Crystal Microbalance(QCM)has high sensitivity to mass changes.The ability to detect different substances can be obtained by covering the electrode surface with films with different properties,which can be applied in different fields.In the field of biological analysis,QCM surface modification is usually carried out by self-assembly of Au-S bonds,but this surface modification has disadvantages such as low efficiency and the need for intermediates with different degrees of complexity.The commonly used polymer surface modification material for QCM is polystyrene(PS),but the excessive surface hydrophobicity of PS material has the potential to cause protein denaturation in the process of protein adsorption.In this paper,the surface of QCM was modified by using polyetherimide(PEI),and the main contents of this paper are as follows:First,different QCM surface modification processes were compared,and the QCM surface was modified by the solvent method using the drop coating process.Second,a reaction cell was established on the surface of the QCM with single-component silica gel as a raw material through a dispenser,and PEI and PS films were covered on its surface using different dispensing processes.In the experiment,it was found that the Q factor of the QCM chip is related to the distance between the edge of the silica gel reaction cell and the electrode.The relationship between the Q factor of the QCM chip and the distance between the edge and the electrode in the silica gel reaction cell is linearly fitted,and the relationship is y=3.6x+797.8,and the goodness of fit R~2 is 0.924.the hydrophobic properties of the formed film surface were characterized by water contact angle experiments,in which the film formed with 0.001 g/m L PEI solution had the smallest water contact angle under the oblate reaction cell scheme,because at this concentration The surface of the film is the most flat,and the corrugated micro-structure cannot be observed under the optical microscope.Then,the detection data of the QCM detection platform developed by the research group has been optimized to make the detection data more stable.The adsorption capacity of bovine serum albumin(BSA)of PS and PEI films was compared.Under the same concentration of BSA solution,PEI and PS had similar BSA adsorption capacity,which may be related to the charge distribution in PEI materials.After BSA is cured on the surface of the QCM chip,its Q factor is reduced by 1100～1300.The surface roughness analysis of the film-modified QCM chip after curing BSA shows that the BSA distribution on the surface of the QCM chip modified by the PEI film is more uniform,which is due to the fact that the PEI film has less water contact than the PS film.horn.Finally,the spike protein was detected by immobilizing ACE-2 on the surface of the QCM modified by the PEI film,by comparing the detected signal value with the noise signal value,and the detection result could be obtained within 15 minutes.