Methylene blue ndi leucomethylene blue: gulu limodzi la redox, mitundu iwiri

Wophunzira amathira madontho angapo a utoto wabuluu m’botolo la labotale, kulizunguliza pang’onopang’ono, n’kuona mtunduwo ukusowa. Amagwedeza botololo ndipo mtundu wabuluu umabwerera. Palibe chomwe chinawonjezedwa kapena kuchotsedwa pakati pa mikhalidwe iwiriyi kupatulapo maelekitironi ndi kukhudzana ndi mpweya. Botolo limenelo lili ndi zonse zomwe nkhaniyi ikufotokoza: methylene blue ndi mnzake amene walandira maelekitironi, leucomethylene blue, kusinthana m’gulu la redox lomwe lingasinthe kupita ndi kubwerera, ndipo mtundu ndiwo umasonyeza kusinthako.

Mfundo yothandiza pa ntchito ibwere choyamba. Kusintha kwa mtundu pano si zotsatira zapambali. Ndiko chizindikiro chimene chimagwiritsidwa ntchito poyesa. Aliyense amene amapanga zosakaniza ndi methylene blue, amachita titration nayo, kapena amaphunzitsa nayo ayenera kulemba chilinganizo cha theka la kusinthaku kuchokera m’chikumbukiro, kufotokoza mikhalidwe yomwe imachikankhira kumanzere kapena kumanja, ndi kutchula zosafunika zomwe zimasokoneza zotsatira.

Ziwirizi mu chilinganizo chimodzi

Methylene blue yomwe yataya maelekitironi ndi katayoni ya methylthioninium: dongosolo lathyathyathya la phenothiazinium lokhala ndi sulfure ndi nayitrojeni mu mphete yapakati, komanso gulu la dimethylamino kumapeto kulikonse, lomwe limaperekedwa ngati mchere wa chloride. PubChem imalemba izi ngati methylthioninium chloride, C.I. Basic Blue 9. M’madzi, monoma imayamwa kuwala pafupi ndi 664 nm, ndipo zimenezi zimapanga mtundu wabuluu umene diso limaona.

Leucomethylene blue (LMB) yomwe yalandira maelekitironi ili ndi chimango chomwecho, koma nayitrojeni ya mu mphete yapakati yawonjezeredwa protoni ndipo kromoforo, mbali yopanga mtundu, yasokonekera. Ilibe chaji pafupi ndi pH yopanda asidi kapena alkali ndipo imakhala pafupifupi yopanda mtundu. Kuyamwa kwake kuwala kooneka ndi kochepa kwambiri, koma ili ndi gawo lamphamvu loyamwa kuwala kwa ultraviolet pafupi ndi 258 nm (zolemba za PubChem za leucomethylene blue, CAS 613-11-6). Chiwerengero cha maprotoni mu chilinganizo cha theka la kusinthaku chimadalira pH, chifukwa mawonekedwe omwe alandira maelekitironi amawonjezeredwa maprotoni mu asidi (miyezo ya pKa ili pafupi ndi 4.5 ndi 5.8). Mikhalidwe itatu imafotokoza kuchuluka komwe kumapezeka pa ntchito:

MB(+) + 2 e(-) + H(+) <=> LMB, buluu <=> yopanda mtundu (pafupi ndi pH yopanda asidi kapena alkali, protoni 1)

MB(+) + 2 e(-) + 2 H(+) <=> LMBH(+), buluu <=> yopanda mtundu (asidi wapakatikati, maprotoni 2)

MB(+) + 2 e(-) + 3 H(+) <=> mawonekedwe a leuco owonjezeredwa maprotoni awiri (asidi wamphamvu, maprotoni 3)

Zilinganizo zonse zitatu zimafotokoza gulu lomwelo pamikhalidwe yosiyanasiyana yowonjezeredwa maprotoni, mfundo yomwe mabuku okhudza khalidwe la redox la utoto wa thiazine amafotokoza mwadongosolo. Kudalira pH kumatsatira chilinganizo cha Nernst cha Ox + mH(+) + 2e(-) <=> Red, ndipo kumapereka kutsetsereka kwa pafupifupi 29.6, 59.2, kapena 88.7 mV pa gawo lililonse la pH pamene m = 1, 2, kapena 3. Kutsetsereka koyezedwa pafupi ndi 28, 58, ndi 87 mV pa gawo lililonse la pH kumatsimikizira kugawa kumeneku, choncho potenshiyalo yolembedwa popanda pH yake ilibe tanthauzo.

Zomwe chilinganizochi chimauza wopanga zosakaniza

Mfundo zitatu zimachokera ku stoichiometry, kuwerengera kuchuluka kwa zinthu zomwe zimachita nawo kusintha. Choyamba, maelekitironi awiri pa molekyulu amatanthauza kuti pa kusintha kwake konse, methylene blue ndi chizindikiro komanso mkhalapakati wa maelekitironi awiri, osati chonyamula elekitironi imodzi. Chachiwiri, maprotoni amatenga nawo mbali, choncho potenshiyalo yovomerezeka imasintha ndi pH monga tafotokozera pamwambapa. Chachitatu, potenshiyalo yovomerezeka pa pH 7 ili pafupi ndi +0.011 V poyerekeza ndi elekitirodi yokhazikika ya haidrojeni (pafupifupi +0.53 V pa pH 0). Izi zimayika gululi pakati pa zinthu zosakhala zamphamvu kwambiri zolandira maelekitironi: zamphamvu mokwanira kutenga maelekitironi kuchokera kwa opereka abwino monga NAD(P)H kapena ascorbate, koma zofooka mokwanira kuwapereka kwa okosijeni wosungunuka kapena malo okhala ndi chitsulo cha ferric. Malo apakatikati amenewa ndi chifukwa chenicheni chimene utotowu umasinthasinthira m’malo mongokhala pa mbali imodzi.

Kuchuluka kwa chinthucho kumawonjezera vuto lina. Kuchuluka kukapitirira pafupifupi maikromola zana m’madzi, mogwirizana ndi konstanti ya kulekana kwa dima kukhala ma monoma yomwe inalembedwa pafupi ndi 170 mpaka 250 uM pa pH 7, makat ayoni omwe ataya maelekitironi amaunjikana kukhala ma dima ndi magulu akuluakulu. Gawo lawo loyamwa kuwala limasunthira pafupi ndi 610 mpaka 615 nm. Choncho sipekitiramu yomwe nsonga yake ikuoneka yosiyana ndi yoyembekezeredwa ingatanthauze kuti zinthu zaunjikana, osati kuti pali zosafunika. Chepetsani kuchuluka kwake m’madzi kaye, kenako muweruze.

Mikhalidwe yomwe imayendetsa kusintha mbali iliyonse

Tebulo ili m’munsili ndi lothandiza pa ntchito ya pa tebulo la labotale. Kulandira maelekitironi kumafuna chinthu chopereka maelekitironi; kutayanso maelekitironi kumafuna chinthu chowalandira, ndipo nthawi zambiri mpweya umakwanira.

Chilichonse m’tebuloli chimatsatira chilinganizo chomwecho. Chokha chomwe chimasintha ndi mphamvu yoyendetsa kusinthako. Umu ndi mmene gululi lingasinthire kupita ndi kubwerera: njira ndi yomweyo, koma imayendetsedwa mbali zosiyana pamikhalidwe yosiyana.

Kufotokoza botolo labuluu

Njira imene chionetserochi chimagwirira ntchito iyenera kufotokozedwa momveka bwino chifukwa ndi chitsanzo chaching’ono cha gululi. M’madzi a glucose okhala ndi alkali, alkali imalimbikitsa kusintha kwa glucose kukhala enol, ndipo enediolate yomwe imapangika imapereka maelekitironi kwa methylene blue kuti ikhale leucomethylene blue. Choncho botololo limakhala lopanda mtundu. Kugwedeza kumasungunula okosijeni wochokera mumpweya wa pamwamba pa madziwo; okosijeniyo amatenga maelekitironi ku mawonekedwe a leuco, ndipo mtundu wabuluu umabwerera. Kusiya botolo osaligwedeza kumachepetsa okosijeni wosungunuka pafupi ndi malo omwe kusintha kumachitikira pamwamba, ndipo glucose imapambananso. Kusinthasinthaku kumapitirira mpaka glucose itatha, ndipo kugwedeza kulikonse ndi chilinganizo cha Nernst chooneka ndi maso: kuwonjezera ntchito ya chinthu cholandira maelekitironi kumasunthira kufanana kwa kusintha kumbali ya buluu.

Radikali yapakati

Kusintha konse kumasuntha maelekitironi awiri, koma masitepe oyambirira amasuntha imodzi pa nthawi. Pakati pa katayoni yabuluu ndi mawonekedwe a leuco opanda mtundu pali radikali ya semiquinone yapakati. M’malo mounjikana, zambiri mwa izo zimasinthana maelekitironi n’kubwerera ku ziwiri zoyambirirazo. Potenshiyalo yake ya elekitironi imodzi, yomwe ili pafupi ndi minus 0.23 V pa pH 7, ili pansi kwambiri pa potenshiyalo yapakati ya kusintha konse kwa maelekitironi awiri. N’chifukwa chake radikali imakhalabe yochepa pamene dongosololi lili pa mkhalidwe wokhazikika. Izi n’zofunika pa zifukwa ziwiri. Utotowu ukawunikiridwa, umafika pamikhalidwe ya mphamvu yokwera yomwe imatsegula njira za ma radikali. N’chifukwa chake madzi okhala ndi methylene blue amakhudzidwa ndi kuwala, komanso chifukwa chake chemistry yochititsidwa ndi kuwala iyenera kukhala m’ndondomeko iliyonse yoyesa kukhazikika kwake. Ndipo kuchuluka kukakhala kwakukulu, mawonekedwe omwe ataya maelekitironi amakhala ma dima. Izi zimasintha sipekitiramu ndi liwiro la kusintha lomwe limaoneka, popanda kusintha gulu lenilenilo. Palibe mwa mfundozi chimene chimalepheretsa kusintha kubwerera. Zonsezi zimafotokoza zomwe zimaoneka ngati kusintha kosabwerera.

Ochokera ku kuchotsedwa kwa methyl amasintha miyezo

Chotsani magulu a methyl pa nthambi ziwiri za dimethylamino ndipo gululi limakhalabe, koma makhalidwe ake amasintha. Malo oyamwa kuwala kwambiri amayandikira mbali ya buluu pang’onopang’ono nthawi iliyonse methyl ikachotsedwa: methylene blue pafupi ndi 664 nm, Azure B pafupi ndi 654, Azure A pafupi ndi 630, Azure C pafupi ndi 615, ndi thionine pafupi ndi 600 nm. Azure B, yomwe ilibe gulu limodzi la methyl, ndiyo yoyandikana nayo kwambiri: ndi chimodzi mwa zinthu zazikulu zomwe zimapangika methylene blue ikasinthidwa m’thupi, komanso ndi chosafunika cholembedwa kuti chimapezeka mu methylene blue. Azure A ndi Azure C zimapitiriza mndandandawu ndi chimango chomwecho chomwe chimatha kuchita redox. Thionine, yomwe magulu ake onse awiri a amino achotsedwa methyl kwathunthu, ili kumapeto ndi potenshiyalo yovomerezeka pafupi ndi +0.06 V pa pH 7, poyerekeza ndi methylene blue pa +0.011 V. Choncho imalandira maelekitironi mosavuta kwambiri. Potenshiyalo za redox m’mndandandawu zimadalira malo omwe zinthu zili ndi elekitirodi, choncho yerekezerani miyezo yokha yomwe yapezeka pamikhalidwe yofanana. N’chifukwa chake kufufuza mitundu ndi kuchuluka kwa zosafunika ndi nkhani ya redox, osati kungolemba kuti chinthucho n’choyera. Azure B ya maperesenti angapo imatanthauza maperesenti angapo a gulu lina la redox m’botolo, ndipo Azure B monga chosafunika komanso chinthu chopangidwa ndi kusintha m’thupi imafotokoza mmene gawo limenelo limayendetsedwera.

Kumene zamoyo zimalowera

Mkati mwa selo lofiira la magazi, NADPH imapereka maelekitironi kwa methylene blue kuti ikhale leucomethylene blue. Kenako mawonekedwe a leuco amapereka maelekitironi kwa chitsulo cha ferric cha heme, kubwezeretsa hemoglobin ku mkhalidwe wa ferrous. Njira imodzi imeneyi yotumizirana maelekitironi ndiyo maziko a chemistry ya kugwiritsa ntchito methylene blue pa methemoglobinemia yomwe munthu wapeza pambuyo pake. Chilichonse chimene chimatsatira kutumizirana kumeneko, kuphatikizapo kagayidwe kopanga mphamvu, kuyenda kwa maelekitironi m’mitochondria, ndi zotsatira zilizonse m’zamoyo, chili mu nkhani ya kutumiza maelekitironi m’mitochondria ndipo chasiyidwa kumeneko mwadala.

Gulani gulu la redox, osati mtundu wokha

Ubwino wa utoto wa redox umadalira miyezo yake. Kuyera kwambiri n’kofunika chifukwa methylene blue yosatsatira USP nthawi zambiri ndi ya ntchito ya nsalu. Imakhala ndi Azure B, zitsulo zolemera, kapena zotsalira za zosungunulira zomwe zimasintha miyezo ya redox ndi kusokoneza malo omaliza a titration, koma palibe ndondomeko yopaka utoto yomwe imazifufuza. Ogulitsa ambiri amene amati zinthu zawo zikugwirizana ndi USP amayesa zitsulo zolemera zokha n’kunena kuti zakwanira. Kutsatira miyezo yonse kumaphatikizapo kutsimikizira chinthucho, kuyeza kuchuluka kwake, zosafunika za organic, zotsalira za zosungunulira, zosafunika za elementi, zotsalira pambuyo powotcha, malire a tizilombo, ndi endotoxin za mabakiteriya. Nkhani ya mmene mungasankhire methylene blue ya mulingo wopangira mankhwala imafotokoza mmene mungawerengere zikalata zimenezo. Blupreme imagwira ntchito ndi wopanga methylene blue wa makampani opanga mankhwala, imayesa miyezo yonse ya USP, ndipo imasindikiza COA yonse. Mtundu ukakhala womwe ukuyesedwa, zikalata zimenezo ndi mbali ya chipangizo choyesera.