Application Of Novel Functionalized Carbon Polymer Dots For Rapid Brain Injury Detection

Research Background:In forensic practice,brain injury occurs in accidents,but the forensic identification of brain injury has been a major problem for forensic practitioners.Mild traumatic brain injury(m TBI)accounts for about70%-90% of all traumatic brain injuries,and its clinical manifestations are relatively mild,imaging manifestation is not significant,and the degree of early injury and distant neurological symptoms and mental impairment of m TBI are not fully match.The degree of early injury of m TBI is not completely compatible with the degree of distant neurological symptoms and mental disorders.In the forensic identification process,the subjective cooperation of the subject is influenced by factors and the lack of more objective indicators,which often lead to different or even very different identification results.Therefore,the rapid and accurate detection of m TBI and its further objective assessment is a pressing challenge in forensic identification practice.Currently,m TBI is mainly diagnosed by a combination of the Glasgow coma scale(GCS)scoring system,neurological and imaging examinations.Although the GCS score is the most widely used and can be more effective in assessing the neurocognitive status and providing information about the patient’s prognosis,it is more subjective.In addition,typical patients do not have clear external damage and pathology on conventional computed tomography and magnetic resonance imaging scans,while imaging is more difficult to accurately diagnose at an early stage because of the minimal damage and small hemorrhage in m TBI.Modern imaging techniques and clinical scoring with comprehensive analysis of relevant biomarkers are the current trends in m TBI identification.For the detection of many m TBI biomarkers,traditional enzyme-linked immunosorbent assay(ELISA),gel electrophoresis technique and real-time quantitative polymerase chain reaction(RT-q PCR)are still used.These assays have a high sensitivity to some extent,but still have the defects of a single simple target index,a small number of fixed-point tests,complex and expensive detection process.Therefore,it is of forensic importance to explore new methods for m TBI biomarker detection.In recent years,the emergence of nanoprobe technology has provided the possibility of rapid forensic detection of m TBI.Carbon polymer dots(CPDs)-based nanoprobe technology has unique advantages in biomarker detection,firstly,as far as raw materials are concerned,carbon as the main constituent element makes CPDs nontoxic and easy to metabolize,and the preparation cost is low.Based on the advantages of rapid response,high sensitivity and wide detection range,this research investigates the application of CPDs nanoprobes in the rapid detection system of brain injury,and the results demonstrate that the functionalized CPDs nanoprobes that can help to achieve the rapid detection of TBI biomarkers and provide an important basis for the accurate diagnosis of brain injury.Research Goal: Validation of novel peptide-functionalized carbon polymer dot nanoprobes,dual-emission carbon polymer dots,and magnetofluorescent gadolinium@carbon polymer dot nanoprobes for rapid and sensitive detection and cellular imaging of biomarkers in different periods of traumatic brain injury.Research Contents:(1)S100-β is considered one of the important early biomarkers of m TBI.Firstly,a novel peptide-modified CPDs fluorescent nanoprobe(pep-CPDs)was prepared by a one-step hydrothermal method for the rapid and sensitive detection of the important m TBI biomarker S100-β.The optical properties of pep-CPDs were explored by characterizing their fluorescence and UV spectra,and the experimental parameters were continuously optimized to obtain a more sensitive S100-β detection.Finally,the efficacy of this multifunctional nanoprobe for the detection of the target S100-β was explored in biological samples from patients with clinical TBI.(2)SAA protein is a subacute phase protein produced by the liver in response to traumatic brain injury.Firstly,a new type of dual-emitting carbon polymer dots(d CPDs)with dual emission function was prepared,showing two different fluorescence emissions at wavelengths of 420 nm and 575 nm,and its selective and sensitive detection performance of SAA protein in aqueous solution were analyzed.Based on the good biocompatibility and excellent fluorescence performance of this nanoprobe,its multi-color fluorescence imaging in living cells was further analyzed to explore the changes in intracellular SAA protein levels.(3)IL-6 is an inflammatory cytokine during the onset of traumatic brain injury and has been found to act as a subacute phase biomarker.We developed a new bifunctional nanoparticle paramagnetic fluorescent Gd@CPDs constructed with carbon polymer dots and paramagnetic metal ions Gd3+.Further analysis of the paramagnetic behavior and optical properties of the nanoprobe demonstrated that the nanoprobe can be used as a dual-mode FL-MRI nanoprobe.The fluorescence and magnetic properties were further optimized in order to enhance the dual detection of IL-6.By analyzing the nanoprobe in standard samples as well as enabling the monitoring of intracellular IL-6 concentration changes,further expanding its potential for sensitive and rapid detection of IL-6 in forensic samples.Research Results:(1)The novel peptide-functionalized carbon polymer dot nanoprobe based for early diagnosis of m TBI helps to accomplish rapid and sensitive detection of the m TBI biomarker S100-β and enables cytofluorimetric imaging.This multifunctional nanoprobe for rapid detection of S100-β in forensic biological samples has practical applications for clinical diagnosis,treatment and prognostic assessment.(2)Rapid quantitative analysis of the m TBI biomarker SAA protein based on a novel dual-emitting carbon polymer dots nanoprobe for subacute phase diagnosis of m TBI.In this experiment,turn-on type fluorescent probes d CPDs were prepared for the first time to specifically identify the brain injury marker SAA at the live-cell level based on the response.the dual-emitting carbon polymer dots have excellent fluorescence properties and are more sensitive to changes in target analyte levels.In cellular fluorescence imaging experiments,we found that the fluorescence signal of cells spiked with the target analyte SAA protein showed a fluorescent turn-on pattern with more pronounced red fluorescence signal enhancement and less fluorescence background interference,which is expected to be used to track the dynamic changes of brain injury biomarkers in vivo and is of great significance for brain injury diagnosis.(3)Dual quantification of IL-6 based on a novel magneto fluorescent gadolinium@carbon polymer dot multimodal nanoprobe for subacute phase diagnosis of m TBI.The nanomaterials were synthesized by a onestep hydrothermal method for a new fluorescent/magnetic resonance probe,gadolinium@carbon polymer dots,which is a facilely synthesized and low-cost magneto fluorescent nanomaterial with high relaxivity and good biocompatibility compared to common magnetic resonance contrast agents.It also integrates magnetic resonance imaging properties and optical properties into a single nanoparticle in m TBI biomarker detection,which enables rapid and accurate detection of biomarkers and provides an important method and application modality for a multiplex diagnostic mode of m TBI.Research conclusions:In this research,an efficient and sensitive analytical system for the acute and subacute phase biomarkers of m TBI was constructed based on three novel nanoprobes,respectively,and used for detection and analysis of actual forensic samples.Compared with traditional detection methods,the novel nanoprobes improve the sensitivity of m TBI biomarker detection and greatly reduce the labor cost and material cost in the detection process,which is expected to build a nano in vitro diagnostic system for m TBI and greatly promote the identification efficiency of forensic practitioners and enhance the validity and reliability of forensic identification work.Meanwhile,the safety assessment of functionalized polymer dot nanoprobes,long-term toxicity studies and validity investigations in more practical cases need to be further improved in the future.