Biosensors and Bioelectronics

Transcription

1 Laboratory of Biosensors and Bioelectronics Biosensors and Bioelectronics Janos (Vörös), Tomaso (Zambelli) Laboratory of Biosensors and Bioelectronics Institute for Biomedical Engineering, Phones: Janos: Tomaso:

2 Program of Today s Class Goal of the lecture Program plan for the semester Basic definitions Biosensing: Concept, Applications, Sensitivity Bioelectronics: Applications, Some history, Electrolysis Discussions

3 Goal of the Lecture You will learn the motivations behind biosensing and bioelectronics learn the basic concepts in biosensing and bioelectronics be able to solve typical problems in biosensing and bioelectronics learn to locate information fast

4 Definitions Biosensor: 1. A device that detects, records, and transmits information regarding a physiological change or process. 2. A device that uses biological i l materials to monitor the presence of various chemicals in a substance. Bioelectronics: 1. The application of the principles of electronics to biology and medicine. 2. The study of the role of intermolecular electron transfer in physiological processes. Source:

5 Problems Solved with Biosensors Today

6 Glucose Monitoring From a drop of blood Implantable

7 High Throughput Analysis Diagnostics Drug-discovery >800 blood tests per hour >1000 microtiter plates per day

8 Biosensors in Everyday Life Hospitals 8000 samples per hour Home 1 sample within 5 s

9 OWLS Biosensors for Research DWI ZeptoReader QCM-D

10 Cell based Sensing Neurons-on-a-chips Multi-channel recording Physiology of brain tissue slices

11 DNA Microarrays Electronic DNA Array (Nanogen) DNA chip (Affymetrix)

12 Nanobiosensors Nanowire Arrays Ion-channel based sensing Nat. Biotechnol. 23, (2005) Nature 387, (1997)

13 Total volume in 2006 ~7 billion US$ Main Players on the Market

14 Biosensor Principle Bio- Recognitionn Element Transducer Signa al Processing sample Signal

15 Biosample (Proteins) Biosample

16 What is in Blood? Total protein = 50 mg/ml Interesting gproteins <1 ng/ml

17 Recognition Elements sample Bio- Re ecogn nition n Elem ment

18 Suitable Immobilization of Receptors Biotin NTA-Ni 2+ -6his IgG Oriented receptor IgG Suitable linker Stable binding Low non-specific binding Ni NTA his-tag PEG-NTA Sensor Surface Sensor Surface

19 Transducers Bio- Recognitionn Element Transducer sample

20 Transducers by Signal Type Radioactivity Optical waveguides, ellipsometry, SPR, fluorescence, Electrical enzymatic, amperometric, potentiometric, Mechanical Quartz crystal microbalance, SAW device, cantilever devices,

21 Signal Processing Bio- Recognitionn Element Transducer Signa al Processing sample

22 Genomics 31billinb 3.1 billion bases genes Proteins, their function and connections -> Proteomics -> High Throughput Screening

23 Summary of Biosensing Concept

24 Sensitivity of a Biosensor Source: Roger P. Ekins Clinical Chemistry 44(9): (1998) See pdf at the course web-site

25

26

27 Langmuir Isotherm ues Equilibrium Val Model: Langmuir Mmax 1081 ± K 38 ± Conc. [nm]

28

29

30

31

32 Bioelectronics i

33 Definition Bioelectronics: 1. The application of the principles of electronics to biology and medicine. 2. The study of the role of intermolecular l electron transfer in physiological processes. Source:

34 Applications of Bioelectronics Biochips (Biosensors) Implantable Medical Devices Prosthetic Devices (Hearing Aids, Artificial Sight, Limb Replacement) Artificial Organs Electronic Pills Surgical and Medical Devices Biofuel Cells Molecular Motors Molecular Electronics Biofabrication Templates i /

35 Some History

36 The Electric Ray Torpedo torpedo

37 The Birth of Electrophysiology

38 Animal Electricity=Bioelectronics 26 th January 1781 Luigi i Galvani

39 Galvani s Experiments G l i (1791) fi h d h f l h h l h i i i Galvani (1791) first showed that frog muscle contracts when the muscle or the innervating nerve is touched with a metal arch. Galvani interpreted his observation in analogy to the electric organ as a discharge of electrical energy stored in the muscle cells.

40 Dispute with Volta

41 Animal(=Bio) Electricity "Le docteur Ure galvanisant le corps de l'assassin Clydsdale." An engraving from Les merveilles de la Science (1867) by Louis Figuier

42 Bioelectricity

43 Let s See Who was Right! Cu e Cu (E = V) Zn e Zn (E = 0.76 V) Fe (E= -044 V) Thus the reaction that is going on is really: Cu 2+ + Zn Cu + Zn 2+ The electric potential is then V ( 0.76 ( 0 6 V) = V

44 Conductivity of Tissue M 1 connective tissue, buffer zone between various tissues - ρ 1 = 10 Ωm; ; M 2 tendons -ρ 2 = 5 Ωm; M 3 extracellular space - ρ 3 = 6 Ωm; M 4 blood vessels - ρ 4 = 2.5 Ωm; M 5 nerves-ρρ 5x = ρ 5y = 10 Ωm ; ρ 5z = 1 Ωm; M 6 bone - ρ 6 = 160 Ωm; M 7 cartilage - ρ 7 = 40 Ωm; M 8 skin and fat -ρ 8 = 20 Ωm; M 9 articular disc - ρ 9 = 60 Ωm; M 10 muscles -ρ 10x = ρ 10y = 13.2 Ωm; ρ 10z = 1.9 Ωm;

45 weight of adult frog: 173 ± 12.5 g; mean leg weight: 38 ± 5.1 g; mean leg length : 16.8 ± 3.2 cm

46 Under typical cellular conditions, ΔG of ATP is approximately 57 kj/mol ( 14 kcal/mol). The ATP concentration inside the cell is typically 1-10 mm.

47 Basics of Memory

48 Examples for Electrodes in Bio-Medicine Deep Brain Electrodes Pacemakers Microelectrode Arrays Glucose Sensor

49 What Makes the Monkey Smile?

50 What Happens on the Electrode? Ion binding Electrolysis Potential ph change Ionic strength change RE

51 Understanding the Bio-(Electronic) Interface at the Nanoscale Y Y Y Surface Bulk Controlling the Function

52 Useful Sources Course material: On the Web: htm //en.wikipedia.org/wiki/ion_gradientgradient

53 Program Feb Introduction/Overview of the field and applications (Ekins paper, Galvani) Janos 01-March Basic notions of molecular adsorption and electron transfer Tomaso 08-March Potentiometric biosensors TZ 15-March Amperometric biosensors TZ 22-March Optical Sensors s (OWLS Theory) JV 29-March AFM for biosensing TZ 12-April Basics of electrophysiology Peter Niederer 19-April Ion channels and patch clamp TZ 26-April Synapse and neuromuscular junction TZ 03-May Protein and DNA high throughput screening methods: Microarrays and JV electrophoresis (Fundamentals) 10-May Acoustic Sensors (QCM theory) JV 17-May NanoBiosensors (Nanowire Sensors by Thomas Helbling, Plasmons by Takumi JV Sannomiya) 31-May Outlook, philosophy and risks (Related reading), Research highlights and brain machine interface JV HOMEWORK Exercises (2007 Excercises, 2007 Exam Questions) JV, TZ

54 L2: Molecular Adsorption and Electron Transfer Transition State Theory s energy G Gibbs activated complex (precursor) reactants transition state Δ G ΔG 0 products reaction coordinate q A + B [AB] C activation energy (barrier) overall released energy k k e Δ G RT k R = N B A = 8.3 J K 1 mol 1 25 Electron Transfer through a Molecular Wire k (x) = k e el 0 el βx 4π 2mΦ β h Α ev 1/2 Φ, barrier in vacuum Φ 34

55 L3: Potentiometric Biosensors Chemical Potential du = dq + dw (1st law of thermodynamics) dq dw Atkins G = U + pv - TS (definition of Gibbs free energy) U μ j n j S,V,n' μ j G n j p,t,n' 4 ph Electrode thin glass membrane highly hl selective to H + 22% Na 2 O, 6% CaO, 72% SiO 2 RE ref V RE ind SiO Na H SiO H + Na ph loga + ΔV H K' loga = + H K' ΔV ph = ( V) solution to be tested ion-selective electrodes (ISE) 16

56 L4: Amperometric Biosensors glucose anode 2Fe(Cp) 2 GOD Ox glucose 2e - 2Fe + (Cp) 2 GOD Red gluconolactone + 2H + glucose + GOD + GOD + 2Fe R ox - 2Fe - 2e 2Fe gluconolactone + GOD GOD + ox + 2Fe R + 2H + 22 Three-Electrodes Cell two - electrodes E appl = E RE sol + IR E WE sol three electrodes ec cell both depending on I E WE sol too bad U R RE 2 U = R in 1 U = 0 U I = R out R 3 U = 0 U WE = 0 27

57 L5: Optical Sensors Newton s Optics 1704 n 2 n 1 Diffraction and Interference Waveguide α θ Cover Support S A F N : = n F sinθ = n air lλ sinα + Λ 2Π m = Φ F + Φ FS + Φ FAC

58 L6: AFM for Biosensing AFM Invention FIG. I. Description of the principle operation of an AFM. The tip follows contour B, to maintain constant force between tip and sample (AFM, sample, and tip either insulating or conducting). G. Binnig et al., Phys. Rev. Lett. 56 (1986) 530 problem of the tip approach to the substrate how to avoid the crash of the tip! 3 AFM & Molecular Recognition approach pulling away (adhesion) recogn (jump to c ition contact) problem how many molecules of the tip bind with the complementary ones of the surface? Only one couple is formed or more? 17

59 L7: Basics of Electrophysiology (Prof. em. Peter Niederer) Model for propagation of action potential

60 Ion Channels L8: Ion channels and patch clamp Different from aqueous pores ion selectivity not continuously open gated 9 Patch-Clamp Recording < 1 μm E. Neher and B. Sakmann, 1991 Nobel Prize in Medicine 12

61 L9: Synapse and neuromuscular junction Electrical Synapse from wikipedia Each gap junction (aka nexus junction) contains numerous gap junction channels which cross the membranes of both cells. With a lumen diameter of about 1.2 to 2.0 nm, the pore of a gap junction channel is wide enough to allow ions and even medium sized molecules like signaling molecules to flow from one cell to the next, thereby connecting the two cells' cytoplasm. Thus when the voltage of one cell changes, ions may move through from one cell to the next, carrying positive charge with them and depolarizing the postsynaptic cell. Gap junction channels are composed of two hemi-channels called connexons in vertebrates, one contributed by each cell at the synapse. Connexons are formed by six 7.5 nm long, four-pass membranespanning protein subunits called connexins, which may be identical or slightly different from one another. 10 Chemical Synapse When an action potential reaches the nerve terminal in a presynaptic cell, it stimulates the terminal to release its neurotransmitter. The neurotransmitter molecules are contained in synaptic vesicles and are released to the cell exterior when the vesicles fuse with the plasma membrane of the nerve terminal. The released neurotransmitter binds to and opens the transmitter-gated ion channels concentrated in the plasma membrane of the postsynaptic target cell at the synapse. The resulting ion flows alter the membrane potential of the target cell, thereby transmitting a signal from the excited nerve. 11

62 L10: Microarrays and electrophoresis Microarray Readers Sequencing with Gel Electrophoresis Traditional Capillary

63 L11: Acoustic Sensors The QCM-D Technique Decay-based QCM readout DNA hybridization Larsson, L. et al., Anal Chem, 2003, 75: QCM-D, optical readout and AFM Rodahl M. et al., Rev Sci Instr, 1995, 66, Höök, F. et al., PNAS, 1998, 14, 1729 Reimhult et al., Anal Chem, 2004, 76, 7211

64 L12: Nanobiosensors Nanobiosensors: Ion-Channel Based Sensing Nanobiosensors: Nanowire Arrays B.A. Cornell et al. Nature 387, (1997) Nat. Biotechnol. 23, (2005) Nanobiosensors: Transmission Plasmon Biosensor Au Ag Immobilization of Single Vesicles on Nanopatterns 100nm 100nm Angewandte Chemie International Edition 42, (45), , 2003

65 L13: Brain Machine Interfaces Examples for Electrodes in Bio-Medicine Deep Brain Electrodes Pacemakers Microelectrode Arrays Glucose Sensor

66 Thank You! Janos (Vörös), Tomaso (Zambelli) Laboratory of Biosensors and Bioelectronics Institute for Biomedical lengineering, Phone: Janos: Tomaso: