| Inorganic semiconducting nanomaterials are widely used in biosensing due to their excellent performance.A series of highly sensitive and highly selective detection methods have been established in important areas such as food safety and environmental monitoring.The specific functions are embodied in:Firstly,inorganic semiconductor nanomaterials which have good optical and electrical properties are suitable as signal elements for biosensors.Secondly,the inorganic semiconducting nanomaterials can be applied to the modification of electrodes because it has large surface energy and specific surface area.Thirdly,the nanomaterial has good biocompatibility and provides a good detection environment for the protein molecules.Biosensors based on nanomaterials not only opened up and developed new solutions in important fields such as food safety and environmental monitoring,but also showed great application value in biological immune detection.In this paper,two kinds of immunosensors based on the preparation and functionalization of inorganic nanomaterials were constructed respectively--photoelectric immunosensor interface based on titanium dioxide nanorod arrays and electrical impedance immunosensor based on functionalized molybdenum disulfide ultrathin nanosheets were used to detect protein molecules.The following work was carried out:1.A TiO2-NAs-based photoelectric immunosensor interface was designed and constructed and applied to the detection of tumor necrosis factor TNF-α.Firstly,we prepared TiO2-NAs with good photoelectric properties and large specific surface area by hydrothermal method.Then the CdS and Mn2+cosensitized TiO2-NAs electrodes were prepared by successive ionic layer adsorption and reaction（SILAR）technique.Its sensitization structure greatly reduces the recombination probability of photogenerated holes and electrons,so the photocurrent intensity has been greatly improved.The secondary antibodies coupled with ZnS NPs（Ab2–ZnS）were used as signal amplification elements in this PEC detection.The prepared ZnS NPs possessed a broad absorption range and could competitively absorb the light energy,reducing the light absorption efficiency for the TiO2-NAs/CdS:Mn2+PEC electrode.Using anti-TNF-αNanobody（Nb）orientedly immobilized to the CdS and Mn cosensitized TiO2 nanorod arrays electrode as receptor molecules and a secondary anti-TNF-αnanobody conjugated with ZnS nanoparticles as the signal amplification element,the PEC samdwich immunosensor for TNF-αwas developed.The proposed method not only has the linear range from 2.0 pg/mL to 200 ng/mL and the detection limit was 1.0 pg/mL,but also has good stability and selectivity.This method can also detect the serum level of TNF-αin patients with lung cancer,which is of great significance for the early diagnosis of lung cancer.2.A variety of excellent functional composites were prepared and applied to the ultra-sensitive detection of Mb based on MoS2 ultrathin nanosheet materials.Firstly,a monolayer MoS2 ultrathin nanosheet with excellent performance was prepared by a hydrothermal method and then functionalized by three methods.Then the immobilization of anti-Mb antibodies（MbAb）onto the surface-aminated MoS2ultrathin nanosheets（MoS2-NH2）was according to the classic EDC coupling reaction between amino groups on the surface of the MoS2-NH2 and carbonyl groups of the MbAb.The impedance immunosensing interface is further constructed by the specific recognition ability between antigen and antibody.The impedance of the sensor interface changes significantly when a certain concertration of Mb molecules are bound to the sensor surface.This method has a highly sensitive detection capability for Mb with a linear range of 0.5 ng/mL to 150 ng/mL and a minimum detection limit of 0.17 ng/mL. |
