| Glypican-3（GPC3）is an important marker of hepatocellular carcinoma.Based on the specific recognition of aptamer and the high loading capacity and signal amplification effect of platinum-based nanocomposites,the specificity and sensitivity of biosensor for the detection of target molecules can be improved.In this study,hemin/reduced graphene oxide/platinum@palladium nanoparticles（H-rGO-Pt@PdNPs）and/reduced graphene oxide-chitosan-hemin@platinum nanoparticles（RGO-CMCS-Hemin@PtNPs）have been first prepared.Then,using GPC3 aptamer(GPC3Apt)as the recognition molecule,three aptamer biosensors have been constructed to realize the highly sensitive detection of serum GPC3.The main contents are as follows:（1）A GPC3 light-addressable potentiometric sensor including the sensitive unit based on H-rGO-Pt@PdNPs,the light source drive circuit,the signal amplifier circuit and the Lab VIEW acquisition platform is constructed.The biosensor is characterized by scanning electron microscopy（SEM）and X-ray photoelectron spectroscopy（XPS）.Under the optimal conditions,the potential shift is linearly related to the concentration of GPC3 in the range of0.0001-3.00μg/m L,the equation is Y=32.6562X+115.1579（Y is the potential shift,X is the concentration of GPC3）with R2 of 0.9881,and the limit of detection（LOD）is 0.212 ng/m L.In addition,the sensor has good specificity,reproducibility and stability,and can be used for the detection of GPC3 in actual serum samples.（2）A non-labeled GPC3 electrochemical aptamer nanobiosensor based on H-rGO-Pt@Pd NPS is constructed.The change of hemin oxidation peak current is measured by differential pulse voltammetry（DPV）to realize the analysis of GPC3.The response current of the nanosensor is linearly correlated with GPC3 concentration in the range of 0.001-10.00μg/m Lwith R2 of 0.9963.The LOD is 0.1845 ng/m Land the sensitivity is 0.2970 nA/μΜ/cm2.Also,the nanosensor has strong selectivity,stability and reproducibility for GPC3 detection,and is suitable for the detection of GPC3 in real serum samples with recovery rates of 95.0%～119.68%.（3）A sandwich-type electrochemicalnanosensor is designed to specifically detect GPC3 levels in serum based on RGO-CMCS-Hemin@PtNPs.Based on,the substrate H2O2is catalyzed under the the peroxidase-like properties of RGO-CMCS-Hemin@PtNPs,resulting in hydroquinone（HQ）is reduced to benzoquinone（BQ）and deposited on the surface of the electrode.The change of HQ reduction peak current is recorded by DPV to detect GPC3.When the concentration of GPC3 is from 0.0001 to1.0μg/m L,the regression equation is Y*=1.7466+0.0637ln（X*+0.0034）（R2=0.9891）.When the concentration of GPC3 is in the range of 3.0-60.0μg/m L,the linear equation is Y=2.6301+0.0298x（R2=0.9908）.Moreover,the nanosensor has a low detection limit（LOD=0.0647 ng/m L）for the detection of GPC3,excellent specificity,reproducibility and stability.The recovery is99.95-104.06%and the RSD is 1.31-5.22%when the nanosensor is used for GPC3 detection of actual serum sample.（4）Comparing the three constructed types of sensors,it is found that using the same platinum-based nanocomposites,the aptamer light-addressable potential sensor has a wider detection range,while the non-labeled electrochemical aptamer nanosensor has a lower detection limit,better correlation coefficient and recovery rate.Therefore,the non-labeled electrochemical nanosensor is more sensitive to the detection of GPC3.At the same time,since the sandwich type electrochemical aptamer nanosensor has two probes for identifying GPC3,its detection range and detection limit are better than those of the non-labeled electrochemical aptamer nanosensor. |
