The Establishment Of Novel On-Site Surface-Enhanced Raman Spectroscopy Detection Methods On Public Security Related New Toxicants

Toxicants are the chemical substances that can damage the normal physical activities,cause functional or organic pathological changes,and even cause death after entering organisms through chemical or physical chemical actions.They mainly include synthetic drugs,plant poisons,animal poisons,illicit drugs,insecticides,herbicides,rodenticides,volatile toxicants,gas toxicants,metal toxicants,and other water-soluble inorganic toxicants,etc.Here the so-called new toxicants mainly refer to some chemicals recently appeared as toxicants in some emergencies such as paraquat,colchicine,succinylcholine,clonidine,and so on,as well as refer to some new types of toxicants,such as new orangophosphorous agents,new psychoactive substances,etc.The emergence of new chemical intoxication incidents and the abuse of new psychoactive substances represented by fentanyl analogues,or morphine analogues,pose a serious threat to national defense security,public safety and social health.Therefore,it is of great significance to establish a rapid,accurate and sensitive on-site detection method for human poisoning and social casualties caused by new toxicants,so as to support the first-aid rescue,clinical diagnosis and treatment,and forensic identification.This thesis focuses on the development of new on-site detection methods towards the objects including a representative of new emerging and breaking toxicants,that is,succinylcholine,and representatives of new-type toxicants,which are,new psychoactive substances such as fentanyl analogues,morphine analogues,etc.There has a wide demand for on-site rapid detection of the above-mentioned types of substances.However,the mainly current on-site rapid detection techniques of colorimetric,infrared spectroscopy,ion mobility,and miniaturized mass spectrometry are during the stage of method development,and the successful applications for the complicated biomedical samples are still limited.SERS is one of the most emphasized on-site rapid detection techniques in recent years.Together with miniaturized mass spectrometry,SERS is considered as the“next generation of on-site detection techniques on chemical toxicants”.As a vibrational spectroscopic technique,SERS provides clear and sharp peaks,and rich fingerprint information.It is more suitable for aqueous detection without the interference from water molecules.It can realize high-sensitive and high-specific detection on complicated matrices when combining some simple and convenient sample pretreatment approaches.By far,there are few SERS reports on the detections of succinylcholine,fentanyl and morphine analogues,among which the applictions are mainly limited to aqueous solutions.Therefore,this thesis focuses on the research of new SERS methods for new chemical toxicants in complicated biomedical matrices,with a highlight of anti-interference and practical suitability.It will provide new method evidence for emergency response of public safety-related events.The thesis is divided into four chapters.The first chapter is a literature review.Firstly,the definition and classification of toxicants,new toxicants,especial psychoactive substances and new psychoactive substances were summarized.With an emphasis on the objects of this thesis,we introduced the physical and chemical properties,in vivo mechanism of action and metabolic processes,and hazards of succinylcholine,morphine and fentanyl analogues,respectively.We then discussed the development of the on-site and off-site analysis and detection on these substances till now.Secondly,focusing on SERS technique,we elucidated the discovery and development of the Raman spectroscopy and SERS,enhancement mechanism,fabrication of SERS substrate and"hot spots".Finally,based on the current status of SERS detection methods of the above three types of substances,which is rare or never have been established,we put forward the basis and the main research contents of this thesis.In the second chapter,we developed an on-site SERS quantitative detection method for succinylcholine in complicated biomatrix.Guided by the basic concept of"inorganic salt-induced gold nanoparticles?AuNPs?to achieve efficient aggregation and produce a large number of SERS"hot spots"",we found that,MgI₂-induced aggregation provided more SERS“hot spots”,as well as effectively quenched high fluorescence background generated by higher laser power.Moreover,higher pH improved the electrostatic interaction between AuNPs and succinylcholine.Succinylcholine can be stable for a long time under alkaline conditions due to the adsorption onto the huge surface area of AuNPs.In our method,the metabolites,succinylmonocholine and choline,did not influence its SERS detection.Combined with simple sample preparation,we achieved a highly sensitive detection of succinylcholine in plasma and urine samples.The limit of detections?LODs?were 1 ng/mL and 10ng/mL,respectively.During the pretreatment,the addition of acid effectively inhibited the activity of cholinesterase with a precipitation of plasma proteins.At the same time,the addition of protein resisted the agglomeration phenomenon of AuNPs caused by a large amount of inorganic salts in urine.The third chapter is emphasized on the new psychoactive substances such as fentanyl and morphine analogues.Considering that both kinds have the chacteristics of designing structures with various substances,firstly,combining with chemmetrics algorithm,we first realized the SERS classification of fentanyl analogues and morphine analogues based on the molecular scaffold structure,and this classification was well validated in two test sets with concentration or species as variables.Secondly,we achieved the selective SERS detection of trace fentanyl of ng/mL level by a selective enhancement to SERS signals of fentanyl with MgI₂ induced aggregation in chemical samples and urine samples,respectively.In chemical samples,fentanyl could be detected as low as 0.05%from heroin,and 0.002%from four medicinal excipients or raw materials.In urine sample,0.01%fentanyl could be selectively detected from the main metabolite of heroin in urine.As the same time,we achieved the quantitative detection of five representative fentanyls,which include novel fentanyl analogue,major metabolite norfentanil,etc.In the fourth chapter,we emphasized on the preparation of functionalized nanoparticles to integratedly provide selective extraction and enhanced signals,and serve as a novel SERS substrate for the highly specific measurement of the novel toxicants.We successfully prepared functionalized inclusion-based?-CD@AuNPs and magnetic interaction-based M@AuNPs,after a full characterization,we applied these two kinds of functionalized substrates to the SERS detection of fentanyl compound.?-CD@AuNPs with different particle sizes can be readily prepared by a direct reduction method of?-CD,with a maximum particle size of 40-45 nm and a good uniformity.We then used this?-CD@AuNPs as a substrate to fulfill the functions of selective extraction and sensitive detection of fentanyl,and acheived a LOD of 2 ng/mL,as sensitive as AuNPs substrate prepared from a classical citrate-reduced method.Moreover,M@AuNPs towards selective recognization of fentanyl was successfully prepared by a co-precipatation and reduction approach,and found that the key parameter to achieve the successful detection of fentanyl was the introduction of TEOS.A direct and high-sensitive SERS detection of fentanyl in urine samples without any sample pretreatment can also be offered by M@AuNPs.