DNA Based Biosensors

DNA Based Biosensors DNA Based Biosensors Yingli Fu Biological Resources Engineering University of Maryland, College Park December 10, 2003 Outline Introduction Principles of DNA biosensors Types of D[.]

DNA Based Biosensors Yingli Fu Biological Resources Engineering University of Maryland, College Park December 10, 2003 Outline Introduction Principles of DNA biosensors Types of DNA biosensors Improvement of DNA biosensors DNA biosensor miniaturization References Introduction Biosensor: DNA biosensor: Motivated by the application to clinical diagnosis and genome mutation detection DNA Structure DNA structures -double helix (complementary)  bases: Adenine (A), Guanine (G), Thymine (T), and Cytosine (C)  sugar (deoxyribose)  phosphate group DNA Stability Hydrogen bonding between base pairs Stacking interaction between bases along axis of double-helix Size and base content and sequence Principles of DNA biosensors Nucleic acid hybridization -rennealing b/w the ssDNAs from different sources Perfect match -stable dsDNA, strong hybridization One or more base mismatches weak hybridization Forms of DNA Biosensors Electrodes Chips Crystals Immobilization of DNA Probe onto Transducer Surface Thiolated DNA for self assembly onto gold transducers Covalent linkage to the gold surface via functional alkanethiol-based monolayers Use of biotylated DNA for complex formation with a surface-confined avidin or strepavidin Covalent (carbodiimide) coupling to functional groups on carbon electrodes simple adsorption onto carbon surfaces Types of DNA Based Biosensors Optical, Electrochemical and Piezoelectric Molecular Beacon Based Optical Fiber DNA Biosensors ‘Ligate and light’ Schematics diagram of real-time monitoring of the nucleic acid ligation process by a MB Material and Methods (cont’s) Results Conclusions The (PQQ)GDH/avidin conjugate based DNA biosensor is highly sensitive and selective to the target Salmonla invA virulence gene The sensor response increased with the addition of glucose and in the presence of 6.3 mM glucose the response increased with increasing DNA in the range 5.0x10^81.0x10^5 This DNA biosensor would be applicable for single nuleotide polymorphism detection Improvement Fluorescent Bioconjugated Nanoparticles DNA dendrimers ...Outline Introduction Principles of DNA biosensors Types of DNA biosensors Improvement of DNA biosensors DNA biosensor miniaturization References Introduction Biosensor: DNA biosensor: Motivated by the... simple adsorption onto carbon surfaces Types of DNA Based Biosensors Optical, Electrochemical and Piezoelectric Molecular Beacon Based Optical Fiber DNA Biosensors ‘Ligate and light’ Schematics diagram... Piezoelectric DNA Biosensors quartz crystal microbalance (QCM) transducers Immobilized DNA probe Target DNA Form duplex -mass increase Decrease in crystal’s resonance frequency Piezoelectric DNA Biosensors