Biological Pores Proteins and Peptides Nanoscopic Pathways - Passage of Ions, other Charged or Polar molecules Short peptides - Self-Assemble to Pores Large Transmembrane Ion Channel Proteins Functions - Maintaining cell homeostasis - Signaling and Communication - Defense against pathogens - Transport of proteins & nucleotides
Toxic Peptides Viral Pores PorinsTranslocator Biological Pores Aquaporins Pores of ER Nuclear Pore Membrane Complex Attacking Ion channel Complex Proteins
Biological Pores In Nanobiotechnology Capability to be Regulated 3D Structure on Specificity the Nanoscale Pore ProteinMainly Ion Channel proteins, antimicrobial and toxic peptides, complementsystem are attractive for the developing field of nanobiotechnology
Models of Lipid MembranesFor their application in nanobiotechnology, ionchannel proteins and pore-forming peptidestypically have to be reconstituted intolipidmembranes
Supported Planar Lipid Liposomes Droplet Interface Lipid Bilayer Bilayers Bilayer SystemsMost of the applications of proteinaceous nanopores arebased on current recordings through planar lipid Bilayers. Thistechnique was developed in 1962 by Mueller et al.
NanomedicineNanomedicine may be defined as the detection,treatment and prevention of human biologicaldisorders at the molecular level, using engineerednanodevices and nanostructuresTherapeutic applications Delivering medication to the exact location Application in cancer therapy Killing of bacteria, viruses Repair of damaged tissues Skin and dental care
Applications of pore-forming peptides and proteins in nanomedicine.1. Cancer treatment2. Drug delivery3. Antimicrobial drug development
1. Cancer Treatment Targeted cytolysis of cancer cells that uses biological pores Endotoxin Bacillus thuringiensis Diptheria toxin Corynebacterium diptheriae
Using a multimeric pore with a built-in ‘trigger’ system to target and kill cancer cells α- hemolysin pores Bacterial pore- forming protein, Aerolysin
2. Delivery of Macromolecules into Cells1. GramicidinDNA transfection protocol has been developed using agramicidin–lipid–DNA complex to deliver a plasmid DNA to avariety of mammalian cells2. Listeriolysin O (LLO)LLO liposomes is an efficient vaccine delivery system. Act as adelivery vehicle for macromolecules such as proteins into cellsboth in vitro and in vivo.3. Anthrax toxinTargeted delivery of antigens for generating protective antiviralimmunity. Goletz et al. employed this toxin to deliver a portion ofthe human immunodeficiency virus-1 (HIV-1) envelope proteinto the cytosol of living cells
3. Development of Antimicrobial DrugsPore-Forming Peptide Antibiotics Nystatin Defensin Gramicidin Melittin Cecropin
Model for membrane lysis by AMPs α-helical peptide 6.1. 4.2. 5.3.
Nanosensing Nanosensors are any biological, chemical, or surgical sensory points used to convey information about nanoparticles to the macroscopic world Detecting single molecules is a useful advancement for applied fields such as medicine, environmental pollution monitoring Sensing platforms based on transmembrane channels offer high sensitivity, often require no labeling, and are relatively economical
Applications of Biological Pores in Sensing1. Nanopore-based sensing of polymers2. Detection of small ions and organic molecules by biological pores3. Nanopore-based sensing of polynucleotides4. Using nanopore recordings to monitor enzyme activity
1. Nanopore based sensing of polymers α-HL pore α-HLTo determine the size of polymer To study polymer chain elongation
2. Detection of small ions and organic molecules Resistive Pulse sensing of Analytes
3. To monitor enzyme activityα-hemolysin based platform for monitoring the cleavage of a peptide by protease
4. Nanopore-based sensing of polynucleotidesIdentification of base mutations Identification of nucleotides
NanoelectronicsNanoelectronics is a branch of nanotechnology thatuses single molecules, or nanoscale collections ofsingle molecules, as electric components.
Applications of Biological Pores in Nanoelectronics1. Biological nanopores as current rectifiers2. Biological nanopores for development of bio- inspired batteries
Biological nanopores as current rectifiersBiological pores that exhibit rectification properties have been used forgeneration of membrane potentials, sensing of enzymatic reactionsand building basic bioelectrical circuits OmpF from E. coliAlacaraz et al. demonstrated that its reconstitution into a planar lipidbilayer, which separated solutions of different pH values, led to currentrectification α- hemolysinBy controlling the incorporation of the engineered a-hemolysin into lipidbilayers between specific droplets, formation of droplet networksoccured that acted as rectifier circuits Gramicidin poresYang and Mayer incorporated chemically modified gramicidin poresi.e. oppositely charged gramicidin-derivatives in each leaflet of thelipid bilayers. These heterodimeric gramicidin pores rectified current
Biological nanopores for development of bio- inspired batteries One intriguing development of bio- nanoelectronics is engineering of bio-inspired mechanisms for providing electrical power based on rectifying biological pores in membranes. Using this principle, Bayley’s group recently developed a bio-inspired battery that employed α- hemolysin pores to generate a membrane potential across a lipid bilayer
Biological pores solved the following set ofchallenges with synthetic pores-1. Non-specific binding of biomolecules (in particular proteins) to the walls of the pores2. Limited reproducibility of fabrication on the subnanometer and even nanometer scale3. Electrical breakdown of extremely thin synthetic membranes that are required to support short pores4. Bubble formation in the pore, and pore clogging
Biological pores solved the issues related to nanotoxicity1. Silver nanoparticles which are bacteriostatic , may then destroy beneficial bacteria which are important for breaking down organic matter in waste treatment plants or farms2. Some forms of carbon nanotubes could be as harmful as asbestos if inhaled in sufficient quantities3. Toxicity have not reported with the use of biological pores.
Challenges with the use of biological pores1. In NanomedicineApplications of biological pores include- Cancer treatment,Antimicrobial drug development, Drug deliveryChallenges that will have to be met for developing therapeuticsbased on biological pores- Appropriate circulation half-life and stability in the human body Effective distribution to the target organs Release in active form at targeted tissue at doses that are effective and elicit minimal side effects Possible adverse immune reactions against these constructs High costs of production
2. In SensingApplications - Detection of small ions and organicmolecules, sensing of polymers, sensing of polynucleotidesand polypeptides, monitoring enzyme activity etc.Challenges- Functional reconstitution of ion channel proteins intobilayer lipid membranes is still rather an art than a science The availability of purified, functional biological pores islimited to a few proteins The cost of available proteins is typically extremely high Limited stability of the lipid bilayer that supports the pore
Future ProspectsThe fascination with biological pores includes their capability todetect single molecules, to sequence short strands of DNA, to rectifycurrent, or to target and kill cancer cellsNanopores on a chip: Applications for analytical tasks in chemistryand biologyIn a joint project at the University of Freiburg, a research group ledby Prof. Dr. Jan C. Behrends, Institute of Physiology have succeededin arranging biological nanopores on a tiny microchip and using it todetermine the mass polymersFitting a Biological Nanopore Into an Artificial One, New Ways toAnalyze DNAResearchers at Oxford University announce a new type of nanoporedevice that could help in developing fast and cheap geneticanalysis.they report on a novel method that combines artificial andbiological materials to result in a tiny hole on a chip, which is able tomeasure and analyze single DNA molecules
"The first mapping of the human genome-where the contentof the human DNA was read off (sequenced) -- wascompleted in 2003 and it cost an estimated 3 billion USdollars. Imagine if that cost could drop to a level of a few100 euro, where everyone could have their own personalgenome sequenced. That would allow doctors to diagnosediseases and treat them before any symptoms arise.” " Professor Cees Dekker” (Kavli Institute of Nanoscience at Delft.)
ConclusionThe use of biological pores can be exploited in-Nanomedicine Precise diagnosis and more effective therapies improved cost-effectiveness of tomorrows medicineSensing More detailed examination of cellular processes effective in identifying molecular targetsNanoelectronics Benefit the energy sector. Items like batteries, fuel cells, and solar cells can be built smaller but can be made to be more effective with this technology