Exploration Of A Biosensor In Response To Bilirubin

Bilirubin,a product of normal metabolic conversion of an iron-containing porphyrin compound that is widely present in animals.It is also a major pigment in the bile secreted by the human liver.The level of bilirubin concentration is an important indicator of whether liver function is normal or not.On the one hand,bilirubin is an antioxidant that has a positive effect on liver cell regeneration.But on the other hand,high concentrations of bilirubin are toxic to the human body.If there is a problem with the metabolic pathway of bilirubin,the following conditions can occur.It will cause the continuous accumulation of bilirubin in the human body,resulting in hyperbilirubinemia,and in severe cases,jaundice may even be formed.It can cause irreversible damage to parts and systems such as the nerves and brain.The detection of bilirubin content in human blood is a very important blood routine indicator,which can intuitively reflect the state of human liver function.Not only that,jaundice,especially in the early neonatal period,has a high incidence,and infants and young children are also the main patient group of jaundice.Therefore,in the infant stage,Of particular note is whether the bilirubin concentration indicator exceeds the standard.Common bilirubin detection methods on the market include enzymatic method,spectrophotometry,fluorescence method,electrophoresis method,chromatography,electrochemical method and other methods.Detection is carried out primarily by kits and specific instruments.However,the operation of the kit is more complicated,requires high labor costs and requires the tester to have a certain professionalism.Instruments for bilirubin concentration detection are more expensive.Not suitable for large-scale promotion.Based on this,we plan to develop a biosensor with E.coli as the host cell that can be applied to detect bilirubin concentrations.Two routes were chosen for the development of the sensor.The type I bilirubin sensor realizes the cross-membrane transport of bilirubin in turn through the synergistic effect of the bilirubin transmembrane transporter,the fluorescent protein covalently bound by the bilirubin oxidase and the oxidation product,which is oxidized to bilirubin and binds to the near-infrared fluorescent protein as a chromophore,and emits a near-infrared fluorescence signal after being excited by red light.This fluorescence signal has strong penetration,and the light scattering of hemoglobin,water and other cell components in this band is relatively small,which can be easily observed,so it is often used for deep tissue imaging and multicolor imaging.The type II bilirubin sensor uses a fluorescent protein that directly binds bilirubin as a luminescent group to remove the less stable bilirubin oxidase,and directly binds bilirubin to the fluorescent protein after transport and emits a fluorescent signal.This sensor has a simple structure,strong stability,and a broader application scenario.The type II sensor can not only complete the qualitative detection of samples that may contain bilirubin,but also respond to the specific concentration of bilirubin.Its detectable range covers at least 0.2 mmol/L.The normal upper limit of bilirubin in a healthy human blood is 17μmol/L.It can be said that the type II bilirubin sensor has the ability to complete the detection of hyperbilirubinemia.As a living organism,biosensors have a certain degree of autonomy and reproductive ability.Compared with the original kit detection method and instrument detection,it greatly reduces the requirements for the detection environment and the professional level of the inspectors.Easy and time-consuming,and the replication of the sensor only requires inoculating it into the medium for growth,which greatly reduces the raw material cost of the inspection and enriches the application scenario.