Preparation of Optical Nanomaterials and Study on miRNA Biosensing

Author:Wang Dan Chen

Supervisor:zhu jun jie


Degree Year:2012





1.Sonochemical Fabrication of 8-hydroxyquinoline Aluminum(Alq3)Nanoflowers with High Electrogenerated ChemiluminescenceWell-defined Alq3 nanoflowers were fabricated via a facile and fast sonochemical route.X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),field-emission scanning electron microscopy(SEM)and transmission electron microscopy(TEM)were used to characterize the structure and shape of the as-prepared product.The results showed that the resulting Alq3 was composed of nanobelts with thickness about 50 nm,average widths of 200 nm,and length up to tens micrometer.The Alq3 nanoflowers exhibited good electrogenerated chemiluminescence behavior.2.Highly reproducible synthesis of hollow gold nanospheres with near infrared surface plasmon absorption using PVP as stabilizing agentAn improved synthetic method has been designed and demonstrated to reproducibly generate hollow gold nanospheres(HGNs)with strong surface plasmon resonance(SPR)absorption in the near infrared(NIR).The HGNs have been synthesized via galvanic replacement of cobalt with gold while utilizing different amounts of poly(vinylpyrrolidone)(PVP)as a template stabilizing agent.Ninety percent of syntheses performed by this modified method resulted in HGNs with an SPR near 800 nm,which is highly desirable for biomedical applications such as photothermal ablation(PTA)therapy,while other polymers(PAA and PEG)did not.Based on absorption and TEM measurements,PVP stabilizes the cobalt template particles via carbonyl-induced stabilization that slows nucleation and growth of the gold shell allowing for the generation of a reproducibly thin shell,thereby inducing a significant red shift of the SPR to 800 nm.The results are significant to various potential applications of HGNs,e.g.cancer therapy and sensing.3.Molecular beacon structure mediated rolling circle amplification for ultrasensitive electrochemical detection of microRNA based on quantum dots taggingMicroRNAs have the potential to be used as biomarkers for diagnosis and prognosis of cancer.MicroRNA-16(miR-16)frequently deleted or downregulated in patients with B cell chronic lymphocytic leukemia and thus can be used as promising biomarkers in B-CLLs diagnosis and prognosis.Herein,ultrasensitive microRNA detection was carried out by combining rolling circle amplification(RCA),quantum dots tagging and anodic stripping voltammetric detection.In this work,molecular beacon structure was designed to capture target microRNA and initiate RCA reaction.Both molecular beacon structure and the locked nucleic acid(LNA)designed contributed to the sensitivity improvement.The method exhibited good specificity to miR-16 and could quantify miR-16 over a 6-decade dynamic range and reach an ultra-low detection limit of 0.32 aM.Additionally,the assay is easy to manipulate and can be used for detecting other cancer related miRNAs by changing bases of the capture MB probe conveniently,thus providing a promising diagnostic approach for early cancer prevention and detection.4.Dual channel sensitive detection of hsa-miR-21 based on rolling circle amplificationRecent researches found the relationship between abnormal expression of miRNA and a variety of human cancers.Thus,microRNA has the potential to be used as biomarker for diagnosis and prognosis of cancer and miRNA detection is in urgent need and attracts much attentions to develop reliable and ultrasensitive new detection methods.Herein,we offered an isothermal,highly sensitive and specific assay for the detection of has-miR-21 with the integration of QD tagging and rolling circle amplification.In addition,we proposed a dual channel strategy for miRNA detection:anodic stripping voltammetry(ASV)and fluorescent method were both performed for the final Cd2+ signal readout.The method exhibited good specificity to has-miR-21 and could obtain comparable detection results by both methods.