Module 3B: Biosensors and biocatalysts (SOMS 5700)

Outline syllabus

1. Introduction: Sensors and biosensors, current sensors, markets, glucose and other medical sensors, next generation sensors.
2. The biological component: Whole cell sensors, enzymes - sensing substrates or inhibitors, antibodies (Mab, Fab, ScFv). and other binding proteins, oligonucleotides and aptamers, molecular imprinted polymers (MIPS).
3. The sensor surface: The base layer. Electrode design. Metals - Au and Pt. Silica and carbon formulations. Screen printing vs sputtered electrodes. Conducting and insulating polymeric films. The tethering layer - self-assembled monolayers (SAMs), alkane thiols, supported phospholipid monolayers and bilayers, affinity lipids.
4. Immobilisation of the sensor molecule: Non-covalent immobilisation - entrapment and multipoint electrostatic atttachment. Covalent attachment via thiol, amino and hydroxy groups. Affinity interactions - avidin/biotin, hexahistidine tags and Ni2+ NTA lipids, complementary oligonucleotides.
5. Transduction of the sensor signal - Electrochemical sensors: Potentiometric sensors, amperometric sensors - sensing substrates or inhibitors, Non-faradaic sensors - impedance/capacitance. Pulsed electrochemical techniques.
6. Electrochemical considerations: Electrochemistry underlying potentiometric sensors, cyclic voltametry and characterisation of the sensor response, chronoamperometry and flow injection analysis. Impedance spectroscopy - relationship between impedance, capacitance, resistance and other parameters.
7. Transduction of the sensor signal - mechanical sensors: Quartz crystal microbalance (QCM), the Sauerbrey equation and measurement of dispersion. Use of 'mass expanders' to improve sensor sensitivity. Acoustic wave sensors.
8. Transduction of the sensor signal - Optical sensors: Fluorimetric sensors, luminescent sensors and plasmon resonance based sensors including interferometry. PEBBLS for sensing intracellular environments.
9. Suppression or substraction of non-specific background interaction at sensor surfaces: Use of PEGylated reagents and surface blocking with bulk protein.
10. Sensor stabilisation: Storage and operational stability. Polyols, polymers and low Mw compounds as stabilising agents for drying and long term storage. Stabilisation mechanisms.
11. Data analysis: Application of sensors for high throughput screening - optical vs. electrochemical technologies. Sensor arrays.
12. Biocatalysis: General principles of using biocatalysts vs conventional catalysts. Using biocatalysts for chiral synthesis using lipases. Use of oxidases, dehydrogenase, P450s. Approaches to cofactor regeneration,use of formate dehydrogenase. Operating enzymes in non-aqueous media.
13. Stabilising and immobilising enzymes: CLECs and CLEAs. Tethering of enzymes to nanoparticles, entrapment in nanoparticles. Uses of nanoparticulate support; biocatalytic reactors - problems and solutions.
14. Types of nanoparticles supports: polymers, coated gold nanoparticles,biosilicate nanoparticles, magnetic nanoparticles. Micelles and reverse micelles. Use of microfluidic reactors for biocatalysis.

Teaching objectives

By the end of this module a student will have a full knowledge of the range of biosensor designs, the principle ways in which they can be interrogated, and an understanding of their current and potential applications.

Assessment

• Practical class, including report 25%
• Oral presentation on a biosensor topic 25%
• 2,000 word essay on a biosensor topic 50%

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