Introduction
SincetheoriginalDNAcalculationwasrealizedbydissolvingDNAinatesttube,thiskindofcomputerconsistsofapileoftesttubesfilledwithorganicliquid,sosomepeoplecallita"testtubecomputer".
TheDNAcomputer"inputs"RNA,proteinsandotherchemicalsubstancesinthecytoplasm,and"outputs"molecularsignalsthatareeasytodistinguish.Inbiomedicalapplications,DNAcomputerscandetectandmonitorthecharacteristicinformationofallactivitiesincellssuchasgenemutations,identifydiseasedcellssuchascancercells,andautomaticallytriggersmalldosesoftreatment.
Features
Comparedwithtraditionalelectroniccomputers,DNAcomputershavemanyadvantages,suchas:
1)Smallsize.Itssmallsizecanhold1trillionsuchcomputersinatesttubeatthesametime.
2)Largestoragecapacity.OnecubicmeterofDNAsolutioncanstore1trillionbinarydata.Theamountofdatathatcanbestoredin1cubiccentimeterofDNAexceedsthecapacityof1trillionCDs.
3)Fastcalculation.Thecalculationspeedcanreach1billiontimespersecond,andmorethantenhoursofDNAcalculationsareequivalenttothetotalamountofcalculationssincetheadventofallcomputers.
4)Lowenergyconsumption.TheenergyconsumptionofDNAcomputersisverylow,equivalenttoonlyonebillionthofthatofordinarycomputers.Ifplacedinlivingcells,energyconsumptionwillbelower.
5)Parallelism.Ordinarycomputersusethemethodofsequentiallyexecutinginstructions.DuetotheuniquedatastructureofDNA,hundredsofmillionsofDNAcomputerscanhandleaproblemfromdifferentanglesatthesametime,andcanperform1billionoperationsatatime,thatis,inparallel.Workgreatlyimprovesefficiency.
Inaddition,DNAcomputerscansynchronizescientificobservationswithchemicalreactions,savingalotofresearchfunding.
Basicprinciples
Thehistoryofmachinecalculationcanbetracedbackto1641,whenthe18-year-oldFrenchmathematicianPascalsuccessfullymanufacturedaneight-digitadditioncomputerwithgeartransmission.Thishasbroughthumancomputingandcomputingtechnologyintoanewstage.Afterhundredsofyearsofhardwork,theworld'sfirstelectroniccomputerwasfinallysuccessfullydevelopedin1946(ENIACiscalledElectronicNumericalIntegratorAndComputer).Sincethen,mankindhasenteredaneweraofcomputingtechnology.
FromtheearliestPascalgearmachinetotoday’smostadvancedelectroniccomputer,itscalculationmethodisakindofsymboltransformationofphysicalproperties,whichisspecificallycomposedofbasicactionssuchas"addition"and"subtraction"of.However,thecurrentDNAcomputinghasundergoneessentialchanges.Calculationisnolongerasignconversionofphysicalproperties,butasignconversionofchemicalproperties,thatis,itisnolongerthe"addition"and"subtraction"operationsofphysicalpropertiesbutthecuttingandpasting,insertionanddeletionofchemicalproperties.Thiskindofcomputingrevolutionisunprecedented.Itisofepoch-makingsignificance.
WeknowthattheDNAmoleculeisalongdouble-helicalchain,coveredwith"pearls"ornucleotides,andhasfourbasesonit,namely:adenine(A),birdPurine(G),cytosine(C)andthymine(T).Throughthedifferentarrangementsofthesenucleotides,DNAmoleculescanexpressalargeamountofinformationpossessedbyvariouscellsofthelivingbody.Mathematicians,biologists,chemists,andcomputerexpertsareinspiredbyit.TheyusethecharacteristicsofDNAtoencodeinformation,firstsynthesizeDNAmoleculeswithspecificsequencestomakethemrepresenttheproblemtobesolved,andthenmakethemreactwitheachotherthroughtheactionofbiologicalenzymes(equivalenttoaddition,subtraction,multiplication,anddivisionoperations)toformvariouscombinations,Andfinallyfilterouttheincorrectcombinationtogetthecodingmoleculesequenceisthecorrectanswer.
Researchprogress
InOctober2011,theUnitedKingdomdevelopedabiologicallogicgateusingbacteria
Thisisthemostadvanced"biologicalcircuit"ever.Suchbiologicallogicgatesaremodular,andtheycanbeinstalledtogether,pavingthewayformorecomplexbiologicalprocessorsinthefuture.
InSeptember2011,theUnitedStates,usingbiologicalcomputerstodestroycancercells
Thisbiologicalcomputercanenterhumancells.Throughlogicalcombinationanalysisoffivetumor-specificmolecules,specificcancercellsareidentified,whichtriggersthedestructionprocessofcancercells.Thisachievementlaidthefoundationforthedevelopmentofspecificanti-cancertreatments.
InJuly2011,Israelusedabiologicalcomputertodetectavarietyofdifferenttypesofmolecules
Thistypeofbiologicalcomputercanautomaticallydetectavarietyofdifferenttypesofmoleculesatthesametime,whichcanbeusedtodiagnosediseases,Controlthereleaseofdrugsandrealizetheintegrationofdiagnosisandtreatment.
In2009,theUnitedStatesdevelopedabacterialcomputerusingE.coli
Thisbacterialcomputercansolvecomplexmathematicalproblems.Andthespeedismuchfasterthananysilicon-basedcomputer.
In2007,intheUnitedStates,aDNAcomputerwasusedtorealizetheRNAinterferencemechanism
ThiskindofDNAcomputercanperformbasiclogicworkandcanbeappliedtoartificiallyculturedkidneycells.ScientistsintroducesinglesiRNAmoleculesfromotherspeciesintocells,andtheDNAcomputercanturnoffthetargetgenethatcompilesacertainfluorescentprotein.
In2006,theUnitedStatesusedaDNAcomputertoquicklyandaccuratelydiagnoseavianinfluenzavirus
ThisDNAcomputercandetectWestNilevirusandavianinfluenzavirusfasterandmoreaccurately,andothersdisease.
In2005,IsraelusedaDNAcomputertorun1billionprogramsdesignedbyDNAsoftwaremolecules
ThisDNAcomputerusesnewsolutionprocessingtechnologyandothertechnologies,andcanrun10HundredsofmillionsofprogramsdesignedwithDNAsoftwaremoleculeshavethepotentialtodetectabnormalmessengerRNAsincellsrelatedtomanytypesofcancer.Provideinformationforcancerdiagnosis.
In2004,China,thefirstDNAcomputercameoutatShanghaiJiaotongUniversity
ThiskindofDNAcomputerisimprovedonthebasisoftheDNAcomputeroftheWeizmannInstituteinIsrael.,Includingsimultaneousdetectionofinputandoutputmoleculeswithtwo-colorfluorescentlabels,real-timemonitoringofautomaticoperationprocesswithsequencer,anduseofmagneticbeadsurfacereactionmethodtosolidifythereactiontoimprovecontrollabilityoperationtechnology,etc.,whichcancompletethesimulationtoacertainextentThefunctionofanelectroniccomputertoprocess0,1signals.
In2003,intheUnitedStates,theworld'sfirstinteractiveDNAcomputerthatcanplaygamescameout
ThisDNAcomputermainlyusesbiochemicalenzymesasthebasisforcomputingsimplegames.
InFebruary2002,theDNAcomputerresearchwentfurther.Japan’sOlympus(Olympus)announcedthatthecompanyandtheUniversityofTokyohavejointlydevelopedtheworld’sfirstcomputerthatcanbetrulyputintocommercialapplications.DNAcomputer.TheDNAcomputertheydevelopedconsistsoftwoparts:molecularcomputingcomponentsandelectroniccomputercomponents.TheformerisusedtocalculatetheDNAcombinationofmoleculestoachievebiochemicalreactions,searchandscreenoutthecorrectDNAresults,andthelattercananalyzetheseresults.Accordingtoinformation,itwillbeofficiallyputintocommercialapplicationthisyear.
InNovember2001,Israeliscientistssuccessfullydevelopedtheworld'sfirstDNAcomputer.Itsoutput,input,softwareandhardwareareallcomposedofDNAmoleculesthatstoreandprocessencodedinformationinlivingorganisms.Thecomputerisonlythesizeofadropofwater,relativelyprimitive,andtherearenorelatedapplications,butthisistheembryonicformofthefutureDNAcomputer.Thefollowingyear,theresearchersmadeimprovements,andtheGuinnessBookofWorldRecordscalledit"thesmallestbiologicalcomputingdevice."
In2000,Israel,theworld'sfirstDNAcomputercameout
Thisistheworld'sfirstDNAcomputer,whichcansolvesomerelativelycomplexcalculationproblems.Ithadnopracticaluseatthetime,butitrepresentedthattheDNAcomputerhadsteppedoutoftheeraofsciencefictionandbecameatechnologythatwasjustemerginginreality.
In2000,scientistsattheUniversityofWisconsin-Madisontookanimportantstepinsimplifyingandscalingupthistechnology.TheytookatesttubedifferentfromthatperformedbyAdlermanandotherpioneers.Intheexperiment,theDNAwasfixedonagold-platedglassslide(aDNAchip).OtherresearchershopetoreturnDNAcomputingtechnologytolivingcells.IntheUK,somescientistshavecarriedoutresearchonsimulatingcomputerlogiccircuitsinsidegeneticallymodifiedcells.
In1994,intheUnitedStates,theDNAcomputerconceptwasfirstproposed
ScientistsusedatesttubecontainingspecialDNAtosolvethefamous"salesmanproblem":therearencities,Asalesmanwantstostartfromoneofthesecities,travelthroughallthecities,andthenreturntothecitywherehestarted,seekingtheshortestroute.Atthattime,evenifthefastestsemiconductorwasusedtocalculatethisproblem,ittookatleasttwoyears.However,ittookonly7daysforscientiststouseDNAcalculations,whichwasbreathtakingandopenedupaneweraofDNAcomputerresearch.
InNovember1994,AmericancomputerscientistL.Adleman(LeonardM.Adleman)solvedaveryfamousprobleminanextraordinaryway—DNAapproach—HamiltondirectlyTheroadserviceproblemiscommonlyknownasthe"salesmantravelproblem".Thebasiccontentis:supposeasalespersonmustsellproductstoeverycityhepassesthrough,butinordertosavetime,hecanonlygothrougheachcityonce,thepathcannotberepeated,andthepathistheshortest,andthisproblemistoletyoudothisThesalesmandesignssuchapath.
Asthenumberofcitiesincreases,theproblemwillbecomemoreandmoredifficult.Asthedifficultyincreases,morepowerfulcomputingpowerisrequiredtosearchforthecorrectpath,andeventuallyitwillbesocomplicatedthatitrequirestheuseofthemostadvancedsupercomputers.Whenthenumberofcitiesreacheshundredsofcities,eventhefastestsupercomputerswillbe"excited"andtheamountofcalculationcanbeimagined.However,withDNAcomputing,theproblemissolved.
ProfessorAdlermanwasinspiredbytheexpressionofDNAmolecularinformation.HecleverlyusedDNAsinglestrandstorepresenteachcityandtheroadbetweencities,andcodedthesequence;inthisway,eachroad"The"stickyends"willbeconnectedtothetwocorrectcitiesaccordingtothebiochemicalrulesofDNAcombination.Then,hemixedthecopiesoftheseDNAstrandsinatesttubeandconnectedtheminvariouspossiblecombinations.Afteraseriesofbiochemicalreactionsforacertainperiodoftime,hewasabletofindtheonlyanswertotheproblem,thatis,onlythrougheachblock.TheshortestDNAchaininthecityatatime.
Scientistsbelievethatduetomaterialsizelimitationsinthesiliconindustry,traditionalelectronictechnologieswillreachtheirphysicallimitssometimeafter2020.Therefore,itisofextraordinarysignificancetoseeknewalternativetechnologies.AlthoughAdlerman'sexperimentonlysolvedtheproblemof7cities,thesolutionofthisproblembrokethroughthesizelimitofcrystallinesiliconmaterials,makingiteasytosolveproblemsthatweredifficultorimpossibletosolvewithtraditionalcalculationmethodsbefore.,Createdaprecedentforcomputingatthemolecularlevelandbecameamilestoneinthefieldofmolecularcomputing.
Adlerman’ssuccesshasattractedgreatattentionfromscientistsfromallovertheworld.In1995,morethan200relevantexpertsfromvariouscountriesfurtherdiscussedthefeasibilityofDNAcomputers.Undertheaction,acertaingeneticcodecanbetransformedintoanothergeneticcodethroughabiochemicalreaction.Thegeneticcodebeforethetransformationcanbeusedasinputdata,andthegeneticcodeafterthereactioncanbeusedastheresultofthecalculation.Usingthisprocesscanmakeanewtypeofbiologicalcomputer.DNAcomputingtechnologyisconsideredtobethemaincandidatetechnologyamongvariousnewtechnologiesthatreplacetraditionalelectronictechnology.
DNAcomputerhasbecomeoneoftheresearchhotspotsofresearchersinmanycountriesintheworld,andbreakthroughshavebeenmade,butitismainlyinthestageoftheoreticalresearchandapplicationexploration.
Applicationprospects
Uniqueadvantages
FutureDNAcomputershaveuniqueapplicationsinthefieldsofresearchlogic,codedeciphering,geneticprogramming,preventionandtreatmentofdifficultdiseases,andaerospaceTheadvantagesofcurrentelectroniccomputersarebeyondreach,andtheapplicationprospectsareveryoptimistic.Forexample,theemergenceofDNAcomputershasmadeitpossibletodevelopcomputersthatoperateinthehumanbodyandcells.Itcanactasamonitoringdevicetodetectpotentialdisease-causingchanges,anditcanalsosynthesizethenecessarydrugsinthehumanbodytotreatcancerandtheheart.Diseases,arteriosclerosisandotherdifficultdiseases,evenintherestorationofblindpeople’svision,willalsoshowtheirtalents.
Human-machineintegration
ItiscompletelyconceivablethatonceDNAcomputingtechnologyisfullymature,thenthereal"human-machineintegration"willberealized.BecausethebrainitselfisanaturalDNAcomputer,aslongasthereisaninterface,theDNAcomputercandirectlyacceptthecommandofthehumanbrainthroughtheinterfaceandbecomeanextensionorexpansionpartofthehumanbrain,anditsupplementsenergybyabsorbingnutrientsfromhumancells.,Withoutexternalenergysupply.LiketheimplantationofDNA-basedartificialsmartchipsintothebraininsciencefiction,thefutureisassimpleasvaccination.Undoubtedly,theemergenceofDNAcomputerswillbringaqualitativeleaptohumancivilization,bringhugechangestotheentireworld,andhaveinfinitelybeautifulapplicationprospects.
Levellimitation
However,duetothelimitationofthecurrentlevelofbiotechnology,theDNAcalculationprocessrequiresconsiderablecostWorkload.Forexample,Adlerman’s“test-tubecomputer”cangetresultsinafewseconds,buthespendsweekspickingthecorrectresults.Also,ifthenumberofcitiesintheexperimentisincreasedto200,theweightofDNArequiredforcalculationwillexceedtheweightoftheearth.Inaddition,hundredsofmillionsofDNAmoleculesareverycomplex,andtheyarepronetodeteriorationanddamageduringthereactionprocess,andfatalerrorsmayevenoccurwhenadsorbedonthetesttubewall.Therefore,itwilltaketimeforDNAcomputerstotrulyenterreallife.
Currently,scientistsinmanycountriesintheworld,includingmycountry,areactivelyovercomingandsolvingtheabove-mentionedproblems.Itisexpectedthatin10to20years,DNAcomputerswillenterthepracticalstage.
Derivativedisciplines
DNAlogicgates,DNAfragments