Detection Of Low-Density Lipoproteins Based On Carbon-Based Light Addressable Potentiometric Sensor

Cardiovascular diseases have become the number one killer of human health.Early diagnosis and treatment of cardiovascular diseases can effectively improve the effectiveness of treatment and reduce the mortality rate of the disease.Low-density lipoprotein（LDL）is an important marker of cardiovascular disease and is commonly used in clinical practice for the early detection of cardiovascular disease.Therefore,there is an increasing emphasis on techniques for the detection of LDL levels in human serum.The carbon-based light addressable potential sensor（C-LAPS）is a new potentiometric electrochemical sensor based on a carbon-based photosensitive layer,which has the advantages of high sensitivity and good stability.In this paper,a novel carbon-based light addressable potential sensor（C-LAPS）was constructed for the determination of LDL based on OPD@NGQDs and a carbon-based photosensitive layer composed of carbon nanomaterials.The main elements are as follows.（1）Preparation of a carbon-based LAPS sensor based on nitrogen-doped graphene quantum dots-phthalimide（OPD@NGQDs）:OPD@NGQDs nanomaterials were synthesized and combined with reduced graphene oxide（rGO）and carboxylated two-dimensional transition metal nitrogen/carbide@reduced graphene oxide（C-MXene@rGO）.Characterisation of OPD@NGQDs and C-MXene@rGO was using UV-Vis,Fourier infrared absorption spectroscopy（FTIR）,X-ray photoelectron spectroscopy（XPS）,fluorescence spectroscopy,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）and linear scanning voltammetry（LSV）proved that the synthesis and preparation of OPD@NGQDs and C-MXene@rGO were successful.（2）Study on the detection of LDL by carbon-based LAPS sensors based on OPD@NGQDs/rGO photosensitive layer:Aminosilanized ITO conductive glass（APTES/ITO）was used as the carrier,and LDL aptamers were organically combined with the OPD@NGQDs/rGO photosensitive layer to form LDL C-LAPS chip.And the LDL C-LAPS chip is combined with the LAPS detecting system to achieve the detection of LDL.Under optimal conditions,detection of LDL in the range of 0.01-0.15μg/m L can be achieved.The linear equation isΔV₁=1819.42C₁-11.33,R²=0.9902（whereΔV₁represents the potential shift of the I-V curve at a normalized photocurrent of 0.5 for different concentrations and C₁ represents the concentration of LDL）;the limit of detection is 6.42 ng/m L.The sensor also exhibits good specificity,reproducibility and stability for the detection of actual serum samples The sensor also demonstrated good specificity,reproducibility and stability,with an error of between 0.91%and 7.89%on actual serum samples,demonstrating its good detection performance.（3）Study on the detection of LDL by carbon-based LAPS sensors based on OPD@NGQDs/C-MXene@rGO photosensitive layer:Modification of LDL aptamer and OPD@NGQDs/C-MXene@rGO photosensitive layer on APTES/ITO to form LDL C-LAPS chip.And the LDL C-LAPS chip is combined with the LAPS detecting system to achieve the detection of LDL.Under optimal conditions,detection of LDL in the range of0.02-0.3μg/m L can be achieved.The linear equation isΔV₂=315.20C₂+22.26,R²=0.9804（whereΔV₂ is the potential shift of the I-V curve at a normalized photocurrent of 0.5 for different concentrations and C₂ is the concentration of LDL）;the limit of detection is10.44 ng/m L.The sensor also exhibits good specificity,reproducibility and stability for the detection of actual serum samples The sensor also demonstrated good specificity,reproducibility and stability,with an error of between 2.49%and 8.61%on actual serum samples,demonstrating its good detection performance.（4）By comparing the performance of C-LAPS based on OPD@NGQDs/rGO photosensitive layer and C-LAPS based on OPD@NGQDs/C-MXene@rGO photosensitive layer for LDL detection,it was found that C-LAPS based on OPD@NGQDs/rGO photosensitive layer has higher sensitivity and lower detection limit.The C-LAPS based on OPD@NGQDs/C-MXene@rGO photosensitive layer has a larger linear range,probably because the OPD@NGQDs/C-MXene@rGO photosensitive layer has a looser porous structure and more abundant binding sites,which can immobilize more LDL aptamers.