Functionalization Of Metal-organic Frameworks And Their Applications In Bioanalysis

The detection of disease specific biomarkers is important for early diagnosis,monitoring and evaluation of diseases;also,it is one of the most powerful techniques for the further understanding of disease biology and development.However,with the in-depth study of disease mechanism,the demands for clinical diagnosis are increasing,especially for the detection of low abundance of biomarkers in non-invasive samples.Therefore,the development of simple,rapid,sensitive and convenient biosensor system for the analysis of biomarker has become a significant research.With the continuous integration of biology,chemistry,and materials,nonmaterials have played important roles in the field of biosensor due to their excellent properties,which greatly promote their development in the field of bioanalysis.Metal-organic frameworks(MOFs)as emerging inorganic-organic hybrid porous nanomaterials have quickly attracted widespread attentions and interests of researchers.Due to their unique physical and chemical properties,such as dispersed metal nodes,flexible porosity,high surface areas,MOFs show excellent performance in biological analysis.In this work,we have established some simple,fast and sensitive biosensor systems for the biomolecular analysis by using different methods to functionalize MOFs materials.The sensing system can be used not only for the analysis of clinical samples,but also suitable for the areas with technology and equipment limited,realizing real-time detection and providing new technical supports for early diagnosis,disease monitoring and effective treatment.The detailed research contents are described as follows:1.Construction of electroactive metal-organic frameworks for the detection of glioblastoma-derived exosomesGlioblastoma is one of the most deadly tumors in the brain,which early diagnosis still remains technically challenging because of the diversity of carcinogenesis and complex composition of blood-brain barrier.Glioblastoma-derived specific exosome can enter the fluid circulation through the blood-brain barrier and contains the bioactive molecules of glioblastoma cells,so it can be used as the non-invasive biomarker for the early diagnosis of glioblastoma.In this chapter,we have proposed a sensitive,label-free electrochemical biosensor system for the detection of glioblastoma-derived exosomes.In the design,methylene blue is packed in the Zr metal-organic frameworks(Zr-MOFs)by using the porous nature MOFs,which endow them with electroactive.Then,the gold electrode is modified with peptide ligands,which can specifically bind with the overexpressed human epidermal growth factor receptor(EGFR)and EGFR variant(v)III mutation(EGFRv III)on the glioblastoma-derived exosomes.Meanwhile,Zr-MOFs encapsulated with a large number of electroactive molecules can bind to the exosome surface for signal labeling and amplification through the interaction between Zr clusters and the inherent phosphate group outside the exosome.Consequently,the quantitative analysis of exosome concentration can be carried out directly by detecting the electroactive molecules inside MOFs.Furthermore,the biosensor can distinguish serum samples from patients with glioblastoma and healthy people,which proves its great prospect in early clinical diagnosis.2.Electrochemical synthesis of conductive metal-organic framework films for the detection of pathogenPathogen infections have aroused significant attentions worldwide because of the extremely severe consequences in the medicine,public health,food safety,and security.Rapid and efficient detection of pathogen is important in the clinical diagnosis and treatment for patients,especially the serious consequence of drug-resistant bacterial infections.In this chapter,we report an electrochemical biosensor for the staphylococcus aureus(S.aureus)detection based on the electrodeposition of Cu-MOFs thin films on the electrode.Cu-MOFs films are directly assembled on the surface of electrode under the negative potential,showing a good electronic conductivity and an enhanced electron transfer properties.The platform not only detects S.aureus by the aptamer-recognition,but also through the specific micrococcal nucleases(MNase)in the supernatant.The dual detection design ensures the stability and accuracy of this method,and the strategy is simple and convenient without extra signal elements,which suitable for the timely clinical detection.Real samples experiments confirm that the biosensor can work well in the complex biological samples,showing the good selectivity,specifically and great potential application in clinical diagnosis.Moreover,MNase is one of the pathogenic factors of S.aureus,so this work can be of great help to analyze the pathogenicity and mechanism of drug resistance of pathogenic bacteria.3.Sensor array for rapid pathogens identification fabricated with peptide-conjugated 2D metal-organic framework nanosheetsIt is significant to detect pathogen of infection disease rapidly and efficiently in the clinical diagnosis.Moreover,microbiome is a complex trait and their different components can lead to different diseases.Therefore,the identification of different pathogens will be more meaningful in the clinical treatment.In this chapter,a simple and reliable sensor array is successfully proposed for different pathogens identification and discrimination based on two-dimensional metal-organic frameworks(2D-MOFs)conjugated with functional peptide.Owing to the unique physical and chemical properties,ultrathin 2D-MOFs can adsorb dye-labeled peptides and consequently quench the fluorescence quickly and efficiently.Nevertheless,after the addition of pathogens,the different bimolecular composition and anionic surface of pathogens will make them to combine with the 2D-MOFs or peptides through the diverse non-specific interactions.Subsequently,the peptides labeled with fluorescent groups can be released form the surface of MOFs to restore their fluorescence intensity.Consequently,the sensor array can rapidly and efficiently identify various pathogens based on the distinct change of fluorescence response.Moreover,results have revealed that this method can discriminate different pathogens with 100%accuracy,even in urine or mixed samples,demonstrating its effectiveness and reliability in the complex biological samples.More importantly,the process of pathogens identification by using the sensor array only takes 15 min,which shows its advantages of fast and effective,and great application value in timely diagnosis,clinical treatment and rapid monitoring of infectious diseases.4.Quantitative analysis of carcinoembryonic antigen based on Au-NPs/metal-organic framework composite nanozymeThe abnormal levels of proteins are often associated with certain diseases,which their detection is of great importance in the fundamental research as well as clinical diagnosis.In this chapter,we propose a colorimetric biosensor for quantitative analysis of protein by using the 2D-MOFs intrinsic peroxidase like catalytic activity.For the better performance of this strategy,Au NPs are reduced in-situ in the surface of the 2D-MOFs nanosheets to combine with aptamer by the Au-S bond,and the composite nanoprobe further improve the sensitivity and selectivity.Then,with the target protein existed,the nanozyme can react with substrate for the colorimetric reaction.MOFs mimic enzyme activity is free from interference by exogenous enzymes or inhibitors,which make the sensing platform more stability.Taking the analysis of carcinoembryonic antigen(CEA)as an example,the results of clinical sample experiments show that the sensor can be used to distinguish the healthy and patient samples,showing good clinical application potential.Additionally,the output signal of this sensor is based on the changes of color,which can be observed with naked eyes simply without any equipment.Furthermore,MOFs can be mass-produced,low cost and easy to use,making the sensor suitable for remote or resource-poor areas and showing great potential application in point-of-care testing(POC).5.Colorimetric sensor array for proteins identification designed by coupling zirconium metal-organic frameworks with DNA-modified gold nanoparticlesThe formation of diseases often involves abnormal expression of a variety of proteins,such as male infertility.Semen is a heterogeneous composition,in which highly abundant proteins are the main effectors of sperm function.Therefore,rapid and accurate identification of semen is of great significance for the diagnosis and personalized treatment of male infertility.However,the complexity and diversity of semen samples impose lots of limitations in the detection.In this chapter,a colorimetric sensor array is constructed for the human semen identification by coupling zirconium metal-organic frameworks(Zr-MOFs)with single-strand DNA decorated gold nanoparticles(ss DNA-Au NPs).In this design,Zr-MOFs can absorb ss-DNA and precipitate ss DNA-Au NPs due to the coordination interactions between the Zr clusters and the DNA phosphate backbone,which makes the color of supernatant fade.When the protein or semen sample is added in the test solution,proteins or other contents in the samples will affect the co-precipitation of Zr-MOFs and ss DNA-Au NPs,and the color of supernatant will change.Therefore,this method can analyze the difference of samples according to the different color of supernatant,and then realize the identification of a variety of proteins.Further studies reveal that the method can completely detect different semen samples based on the differences in inclusions,demonstrating the characteristics of simplicity,feasibility and sensitivity in the application of male infertility diagnosis.