Study On Photoelectrochemical Detection Of Chiral Biomolecules

Chirality is a fundamental property of nature,which plays a crucial role in the life systems on earth.Different enantiomers have the same physical properties,but often exhibit different biological,pharmacological,toxicological and metabolic activities in living systems.Examples of chiral molecules include proteins,amino acids,DNA,enzymes,sugars,and various drugs.The enantiomer differentiation of racemic drugs by the human organism may lead to different therapeutic activities.In most cases,the enantiomers of chiral molecules show significant differences in toxicity,metabolic mechanisms and transport pathways.Generally,only one enantiomer has the required pharmaceutical activity,while the other enantiomer has no therapeutic effect and may even cause serious side effects,resulting in a single enantiomer superior to the racemate.In organisms,only L-amino acids are commonly used to express functional and structural proteins,while D-amino acids are involved in certain diseases.Therefore,in the fields of biology and chemistry,it is necessary to distinguish L-amino acids from D-amino acids.In the past few decades,many methods for recognizing chiral molecules have been reported,such as chromatography,capillary electrophoresis and circular dichromatic methods.However,these methods often have the disadvantages of long response times and high costs.Therefore,it is still very necessary to develop a simple,fast and sensitive detection method for chiral recognition.For large-scale applications,the advantages of low cost and easy preparation are also required.Photoelectric chemistry?PEC?sensing is a new detection method based on nanometer semiconductor.Compared with traditional electrochemical methods,it has better detection sensitivity and detection limit,and better detection performance.However,as enantiomers have the same chemical structure and only show differences in spatial configuration,it is indeed a huge challenge to realize PEC chirality detection of enantiomers.In this paper,based on the good stability,non-toxicity and good biocompatibility of the n-type semiconductor materials titanium dioxide?TiO₂?and bismuth vanadate?BiVO₄?,the sensors used for photoelectric chemical chiral molecular detection were constructed.And the photoelectrical chemical detection of chiral molecules was realized under the simulated sunlight condition.The main content of this paper is divided into the following parts:Chapter one:introductionThis chapter introduces the research background and significance of chiral and chiral recognition.The development status and research progress of chiral recognition methods are briefly introduced.Chapter 2:A Highly Sensitive Dual Response Signal Chiral Sensor for Recognition of Amino Acid Enantiomers Based on Self-standing TiO₂NanochannelsChirality is an intrinsic and essential property of nature,and the enantiomeric discrimination of chiral molecules can pro-vide important information leading to a better understanding of chiral recognition in biological systems and furthering the development of useful molecular devices in biochemical and pharmaceutical studies.Therefore,the exploration of new detection techniques with high accuracy and reliability for high-throughput enantioselective detection is still highly desirable.In this chapter,a chiral enantiomers selective recognition platform based on self-standing titanium dioxide nanochannel arrays?TiO₂ NCAs?is proposed to implement the ionic current rectification triggered photoelectrochemical?PEC?detection,which provides a novel sensing platform to discriminate chiral amino acid through synchronously output dual response signals of ionic current and photocurrent.The utilization of nanochannel arrays guaranteed the high throughput detection and the dual signal model avoided the“false positive”detection.In addition,based on the fabricated detection platform,various chiral substances can be facile detected through integrating different chiral regulation units,which shed light on the construction of reliable chiral sensors for practical applications in biological environment.Chapter 3:Photoelectrochemical enantioselective oxidation of chiral 3,4-dihydroxyphenylalanine based on mesoporous BiVO₄Natural enzymes can efficiently catalyze a variety of biochemical reactions under mild reaction conditions,which show very high substrate specificity and reactivity.Natural enzymes are widely used in biosensors,pharmaceutical industry,food industry and agricultural chemical production.Inspired by natural enzymes,an enantioselective nanozyme was designed in this work.Chiral cysteine?Cys?was used as the chiral discriminator,gold nanoparticles?Au NPs?as the active center and mesoporous bismuth vanadate?BiVO₄?as the artificial enzyme skeleton.The enantioselective oxidation of the chiral 3,4-dihydroxyphenylalanine?DOPA?enantiomer of the L-cys modified nanozyme was achieved.