Electrochemistry ya methylene blue: maelekiturodi, zofufuzira za redox, ndi masensa

Wophunzira wa digiri yapamwamba amachita cyclic voltammetry ya methylene blue pa elekiturodi ya kaboni wangati galasi, amaona nsonga ziwiri zooneka bwino, ndipo amaganiza kuti kupanga sensa kwatha. Patatha sabata imodzi, nsongazo zasintha malo, zachepa, kapena zagawanika, ndipo palibe chilichonse m’ndondomeko yoyesera chofotokoza chifukwa chake. Utotowo sunasinthe. Lingaliro limene muyesowo unakhazikitsidwa silinali lokwanira.

Methylene blue ili ndi malo ake mu electrochemistry pa zifukwa zitatu. Imasinthanitsa maelekitironi mobwerera pa potensiyali zosaopsa kwambiri, imamatira pamwamba pa zinthu ndi kupanga ma polima okhala ngati zigawo zopyapyala, ndipo imalumikizana ndi ma nucleic acid. Lililonse mwa amenewa ndi lingaliro lapadera, ndipo lililonse limalephera m’njira yake. Ndemanga iyi ikuwasiyanitsa: mitundu iwiri ya redox, kuwerenga chizindikiro, elekiturodi yosinthidwa, ntchito yothandizira kusamutsa maelekitironi, ndi kapangidwe ka masensa omangidwa pa zimenezi.

Awiri a redox, mitundu iwiri, proton imodzi

Kachitidwe kakulu pa pH ya pakati nthawi zambiri kamalembedwa ngati katayoni imodzi yomwe yataya maelekitironi, ikutenga maelekitironi awiri ndi proton imodzi kuti ipange mtundu wa leuco wopanda utoto, womwe walandira maelekitironi:

MB+ + H+ + 2e- gives LMB

Potensiyali ya redox ya methylene blue pa pH 7 ili pafupi ndi +11 mV poyerekezera ndi elekiturodi yovomerezeka ya haidrojeni, monga momwe zalembedwera mu kafukufuku waposachedwa wa mmene utotowu umachitira mu Chemistry Europe. Chifukwa proton imodzi imatsagana ndi maelekitironi awiri, potensiyali ya formal imasunthira ku mbali ya negative ndi pafupifupi 30 mV pa kuwonjezeka kulikonse kwa pH ndi gawo limodzi. Kutsetsereka kumeneko ndi chizindikiro choyamba chodziwira kachitidweko chomwe n’koyenera kuloweza. Ngati nsonga yanu imasuntha pafupifupi 30 mV pa gawo limodzi la pH, mukuona mitundu iwiri ya redox yomwe ikuyembekezeredwa. Ngati imasuntha 60 mV pa gawo limodzi, chiwerengero cha ma proton chasintha. Ngati siisuntha n’komwe, chizindikirocho chingakhale chikuchokera ku chigawo chopyapyala chapamwamba chomwe chili ndi kachitidwe kake ka asidi ndi base, osati ku utoto wosungunuka.

Maelekiturodi oyerekezera ndi chinthu chachiwiri choyenera kukumbukira nthawi zonse. Potensiyali zotchulidwa poyerekezera ndi Ag/AgCl, SCE, ndi NHE zimasiyana ndi makumi mpaka mazana a millivolts, ndipo madzi odzazira elekiturodi amasinthanso manambalawo. Potensiyali iliyonse m’nkhaniyi imatchula elekiturodi yake yoyerekezera. Pepala lililonse la kafukufuku losachita zimenezo silingagwiritsidwenso ntchito. Kusiyana kwa kapangidwe ka mitundu iwiriyi, katayoni yosalala poyerekezera ndi molekyulu yopanda chaji yomwe imatha kupindika, nakonso ndi mbali ya nkhaniyi, ndipo tsamba logwirizana nalo la mitundu iwiri ya redox limafotokoza zimenezi mwatsatanetsatane.

Zimene voltammogram ya methylene blue imasonyeza kwenikweni

Pa elekiturodi yaukhondo ya kaboni wangati galasi yopanda zokutira, m’madzi a phosphate buffer omwe pH yake ili pafupifupi pakati, methylene blue yosungunuka nthawi zambiri imapereka nsonga ya anodic pafupi ndi 0.15 mpaka 0.18 V ku mbali ya negative poyerekezera ndi Ag/AgCl, ndi nsonga ya cathodic pafupi ndi 0.20 mpaka 0.25 V ku mbali ya negative poyerekezera ndi elekiturodi yomweyo. Malo enieni amasuntha malinga ndi liwiro la kusanthula, mmene pamwambapo panagwiritsidwira ntchito kale, ndi madzi odzazira elekiturodi yoyerekezera, ndipo muyezo waposachedwa wopezeka kwa onse pa kaboni wangati galasi yopanda zokutira umasonyeza nsonga ya cathodic pafupi ndi 0.18 V ku mbali ya negative pa pH 7.4, pansi pa mikhalidwe yake yoyesera.

Mitundu iwiriyi imafotokozedwa bwino ngati yosinthika mobwerera koma osati mwangwiro. Mitundu iwiri ya redox yosinthanitsa maelekitironi awiri mobwerera mwangwiro ingasonyeze nsonga zotalikirana ndi pafupifupi 30 mV. Mafunde a methylene blue nthawi zambiri amakhala otambasuka kwambiri komanso osalingana mbali ziwiri, ndipo kumatira pamwamba kumapangitsa kumasulira zotsatira kukhala kovuta. Kuvuta kumeneku ndi chizindikiro chothandiza kuzindikira kachitidweko, osati phokoso losafunika. Kuchuluka kwa magetsi oyenda pa nsonga komwe kumawonjezeka molingana ndendende ndi liwiro la kusanthula kumasonyeza utoto womatira pamwamba. Kuchuluka kwa magetsi oyenda pa nsonga komwe kumawonjezeka molingana ndi muzu wa sikweya wa liwiro la kusanthula kumasonyeza utoto wofalikira kuchokera m’madzi. Mizere yambiri yeniyeni ya miyeso imaphatikiza zonsezi, n’chifukwa chake madzi omwewo angapereke nsonga za kutalika kosiyana pa elekiturodi yomwe yangopukutidwa kumene ndi pa yomwe yagwiritsidwa kale ntchito.

Okisijeni wosungunuka amaperekanso magetsi oyenda chifukwa cholandira maelekitironi m’malire omwewo a potensiyali, choncho ntchito yoyezera kuchuluka nthawi zambiri imachitika pambuyo pochotsa okisijeni kapena poganizira mmene okisijeni akukhudzira muyesowo. Komanso methylene blue imaipitsa elekiturodi: utoto womatira umasintha pamwambapo pa kuzungulira kulikonse, choncho kusuntha kwa nsonga pa kusanthula kobwerezabwereza ndi umboni wokhudza elekiturodi, osati chinthu chomwe chikuyesedwa.

Kuchokera ku utoto wosungunuka kupita ku elekiturodi yosinthidwa

Sensa ya zinthu zamoyo yokhala ndi elekiturodi yosinthidwa ndi methylene blue imayambira pa chinthu chosavuta chooneka. Utotowu umamatira kwambiri ku kaboni, choncho kungomiza elekiturodi m’madzi a utoto kumasintha kale pamwamba pake. Kumatira kosavuta kumeneku nakonso ndi kapangidwe kosakhazikika kwambiri, chifukwa utotowo umatulukiranso n’kubwerera m’madzi. Zina zonse m’gawoli ndi njira zothanirana ndi kutuluka kumeneko.

Yankho lodziwika kwambiri ndi poly(methylene blue) yopangidwa kukhala polima pogwiritsa ntchito magetsi. Kuzungulira potensiyali ya elekiturodi m’madzi a utoto kuti utotowo utaye maelekitironi kumayika chigawo chopyapyala chochita redox chomwe chimakhalabe pamalopo bwino kwambiri kuposa monoma yomatira. Ndondomeko yovomerezeka ya mtundu wa Karyakin imagwiritsa ntchito pafupifupi 1 mM ya utoto mu 0.02 M ya borate buffer pafupi ndi pH 9.1 yokhala ndi 0.1 M ya potassium chloride, n’kuzungulira kuchokera pafupifupi 0.40 V ku mbali ya negative mpaka 1.20 V ku mbali ya positive kwa kuzungulira pafupifupi 30, monga zalembedwera mu chikalata cha kafukufuku wa digiri ku Durham chofotokoza njirayi. Buffer ya alkaline ndi yofunika: kukula kwa chigawo chopyapyala kumadutsa m’mitundu yomwe yataya maelekitironi yopangidwa pa potensiyali za positive, ndipo malire a potensiyali ayenera kufika pa mitunduyo.

Mapangidwe ena amathetsa mavuto ena. Maelekiturodi a phala la kaboni ndi osindikizidwa pogwiritsa ntchito chophimba amataya kulondola kwina kuti azitha kutayidwa akagwiritsidwa ntchito. Zosakaniza zokhala ndi nanotubes kapena graphene zimawonjezera malo ogwira ntchito ndi kupangitsa nsonga kukhala zakuthwa. Maelekiturodi a golide okhala ndi zofufuzira zomangirizidwa ndi thiol amagwiritsidwa ntchito pa masensa a nucleic acid omwe afotokozedwa pansipa. Kutsekera utoto pansi pa zigawo zopyapyala za Nafion kumachedwetsa kutuluka kwake koma kumachedwetsanso kuyankha. Funso la kapangidwe limakhala lomwelo nthawi zonse: ndi kulephera kwa mtundu wanji komwe mukuchepetsa, ndipo mwalolera kutaya chiyani kuti muchite zimenezo?

Lingaliro la wothandizira: kusamutsa maelekitironi, osati kungokhala reagent

Monga wothandizira redox wa methylene blue mu cyclic voltammetry, utoto wosungunuka umasamutsa maelekitironi pakati pa chinthu choyesedwa chomwe sichimasinthanitsa maelekitironi mosavuta ndi elekiturodi. Utoto womwe wataya maelekitironi umalandira maelekitironi kuchokera ku machitidwe a mankhwala a chitsanzo, elekiturodi imachotsanso maelekitironi ku utoto womwe wawalandira, ndipo magetsi oyenda omwe amayezedwa amasonyeza kuchuluka kwa kubwerezabwereza kwa kachitidweko. Kuchuluka kwa utoto wofalikira momasuka kumakhala m’makumi a micromolar, pafupifupi 10 mpaka 60, osati mlingo umodzi wokhazikika.

Machitidwe atatu a mankhwala othandizidwa motere amapezeka mobwerezabwereza. Utotowu umathandizira kutaya maelekitironi kwa NADH, kuphatikizapo kubwerezabwereza kwa kachitidwe kogwirizanitsidwa ndi ma enzyme, ndipo zigawo zopyapyala za poly(methylene blue) zimathandizira kachitidwe komweko pogwiritsa ntchito magetsi pamwamba pa elekiturodi. Ukagwiritsidwa ntchito ndi ma oxidase, ungakhale wolandira maelekitironi wopangidwa ndi anthu. M’machitidwe a peroxidase, utoto womwe walandira maelekitironi umasamutsa maelekitironiwo kupita ku zinthu zapakati zomwe zimathandizira peroxide kulandira maelekitironi. Zimenezi zimalola kuzindikira hydrogen peroxide pa potensiyali zotsika zogwiritsidwa ntchito, pomwe zosokoneza zimakhala zochepa. Kafukufuku wa 2025 mu Chemical Science wokhudza kuthandizira kutaya maelekitironi kwa NADH umafotokoza kachitidweko mwatsatanetsatane. Utoto ukakhala wochuluka kwambiri, chizindikiro chakumbuyo cha wothandizirayo ndi machitidwe a okisijeni zingapose chizindikiro cha chinthu choyesedwa, choncho kuchuluka kwa wothandizira ndi chinthu chosinthidwa kuti zotsatira zikhale bwino, osati reagent yongoikidwa mopitirira muyeso.

Masensa a nucleic acid: pamene kulumikizana kumasanduka magetsi oyenda

Methylene blue imalumikizana ndi DNA kudzera m’kusakanikirana kwa kulowa pakati pa zigawo zake, kukokedwa ndi chaji za magetsi, ndi kulumikizana kwapadera ndi guanine. Choncho kuitcha chabe chinthu cholowa pakati pa zigawo za DNA kumachepetsa tanthauzo la machitidwe ake. Mapangidwe a masensa amasintha kulumikizana kumeneko kukhala magetsi oyenda kudzera m’mapangidwe awiri osiyana, ndipo kusokoneza awiriwa ndi cholakwika chofala kwambiri powerenga zolemba za kafukufukuyu.

M’mapangidwe opanda chizindikiro chomangirizidwa, utoto waulere m’madzi umalumikizana ndi DNA yofufuzira yomangirizidwa pamwamba, ndipo kulumikizana kwa zingwe za DNA kumasintha chizindikirocho. Mtundu wofala umachepetsa chizindikiro: DNA yofufuzira ya chingwe chimodzi imasonkhanitsa utoto n’kupereka nsonga yaikulu, pamene kulumikizana n’kupanga DNA ya zingwe ziwiri kumasintha malo ozungulira utotowo ndipo chizindikiro chimachepa. Mapangidwe amenewa nthawi zambiri amafika pa malire ozindikira a nanomolar. Chitsanzo chimodzi chinayika DNA yogwirizana ndi yofufuzirayo pa carbon nanotubes za khoma limodzi zomwe zinali pa golide, ndipo chinanena kuti chizindikiro chinali cholingana molunjika ndi kuchuluka kuchokera 100 mpaka 1000 nM, ndi malire ozindikira pafupi ndi 7 nM, mu Electroanalysis.

M’mapangidwe okhala ndi chizindikiro chomangirizidwa, utoto umamangirizidwa ndi mgwirizano wa covalent ku mbali imodzi ya chofufuzira, mbali inayo imamangirizidwa ku golide kudzera mu thiol, ndipo square wave voltammetry imatsata chizindikiro chomangirizidwacho. Masensa a electrochemistry a aptamer odalira kupindika amakulitsa lingaliro limeneli: kulumikizana ndi chinthu chofunidwa kumasintha kapangidwe ka aptamer ndi kusuntha chizindikirocho poyerekezera ndi elekiturodi. Sensa ya ochratoxin A yogwiritsa ntchito aptamer yokhala ndi thiol ndi utoto womangirizidwa pa golide inanena kuti inkayeza kuyambira 0.1 mpaka 1000 pg per mL, ndi malire ozindikira pafupi ndi 0.095 pg per mL, mu Analytica Chimica Acta.

Kusiyanitsa kumeneku n’kofunika pofufuza mavuto. M’mapangidwe opanda chizindikiro chomangirizidwa, utoto ndi mbali ya madzi omwe akugwiritsidwa ntchito, yokhala ndi kuchuluka kwake komanso kudalira pH. M’mapangidwe okhala ndi chizindikiro chomangirizidwa, utoto ndi mbali ya chofufuzira, ndipo kusintha kwa chizindikiro kumasonyeza mtunda ndi kayendedwe, osati kuchuluka kwa utoto wotengedwa.

Zitsanzo za ma enzyme ndi zosakaniza

Zigawo zopyapyala za poly(methylene blue) zimakhalanso maziko a masensa ogwiritsa ntchito ma enzyme. Sensa imodzi ya ammonium inaphatikiza elekiturodi yosindikizidwa pogwiritsa ntchito chophimba ndi tinthu ta golide ta nanometer komanso chigawo chopyapyala cha utoto, kenako inayika pamwamba pake zigawo za kachitidwe ka glutamate dehydrogenase. Chigawo chopyapyala chimachotsa maelekitironi ku NADH pamene enzyme imaigwiritsa ntchito molingana ndi kuchuluka kwa ammonium: 0 mpaka 300 micromolar, ndi malire ozindikira pafupi ndi 0.65 micromolar, monga zalembedwera mu Biosensors. Ntchito zonsezi zikufotokozedwa mu ndemanga ya 2025 yokhudza utotowu pa kuzindikira zinthu pogwiritsa ntchito electrochemistry mu Analytica Chimica Acta.

Mikhalidwe yoyenera kulembedwa limodzi ndi zotsatira zonse

Tsamba logwirizana nalo lofotokoza njira zoyezera kuchuluka limafotokoza mwachidule mfundo za kukonza miyeso kuti ikhale yolondola. Pa zotsatira za electrochemistry makamaka, zinthu izi ziyenera kukhala m’cholemba chilichonse cha labotale:

Chizindikiro choyezera si mankhwala ochizira

Kusiyanitsa komaliza ndi kumene tsambali lilipo kuti litsindike. Kuchepa kwa nsonga ya square wave pakulumikizana kwa zingwe za DNA kumatsimikizira kuti chizindikiro cha redox chasuntha kapena kuti kulumikizana kwa utoto kwasintha. Sikutsimikizira chilichonse chokhudza zimene methylene blue imachita m’thupi la wodwala. Machitidwe a mankhwala pa kuyeza ndi ntchito m’zinthu zamoyo zimangogawana molekyulu imodzi, osati china chilichonse: kuchuluka kosiyana, malo ozungulira osiyana, komanso maelekiturodi otsutsana omwe m’zinthu zamoyo amalowedwa m’malo ndi nembanemba ndi ma enzyme. Mafunso okhudza chithandizo akhale pa masamba a ntchito m’zinthu zamoyo, ndipo zonena za masensa zigwirizane ndi elekiturodi, buffer, ndi njira zomwe zinapanga zotsatirazo. Chizindikiro cha redox ndi chinthu chofotokozera muyezo. Zizindikiro zotere zimafotokoza kuyesa, osati thupi.