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Posachedwapa, nsanja yopanda mankhwala yolimbana ndi mavairasi yochokera ku nanotechnology pogwiritsa ntchito nanostructures zamadzi zopanga (EWNS) yapangidwa. EWNS ili ndi mphamvu yapamwamba pamwamba ndipo ili ndi mitundu ya reactive oxygen (ROS) yomwe imatha kuyanjana ndikuletsa tizilombo toyambitsa matenda angapo, kuphatikizapo tizilombo toyambitsa matenda tomwe timadya. Apa zikuwonetsedwa kuti mphamvu zawo panthawi yopanga zitha kusinthidwa bwino ndikukonzedwa bwino kuti ziwonjezere mphamvu zawo zoletsa mabakiteriya. Nsanja ya labotale ya EWNS idapangidwa kuti isinthe mawonekedwe a EWNS mwa kusintha magawo a synthesis. Kufotokozera za mphamvu za EWNS (chaji, kukula ndi kuchuluka kwa ROS) pogwiritsa ntchito njira zamakono zowunikira. Kuphatikiza apo, adawunikidwa kuti awone mphamvu zawo zoletsa mabakiteriya motsutsana ndi tizilombo toyambitsa matenda tomwe timadya monga Escherichia coli, Salmonella enterica, Listeria innocuous, Mycobacterium paraaccidentum ndi Saccharomyces cerevisiae. Zotsatira zomwe zaperekedwa pano zikuwonetsa kuti mphamvu za EWNS zitha kusinthidwa bwino panthawi yopanga, zomwe zimapangitsa kuti pakhale kuwonjezeka kwakukulu kwa mphamvu yoletsa. Makamaka, mphamvu ya pamwamba idakwera ndi gawo lachinayi ndipo mitundu ya reactive oxygen idawonjezeka. Kuchuluka kwa mabakiteriya ochotsedwa kumadalira mabakiteriya ndipo kunayambira pa 1.0 mpaka 3.8 log pambuyo poti munthu wamwa mankhwala a aerosol a 40,000 #/cc EWNS kwa mphindi 45.
Kuipitsidwa ndi tizilombo toyambitsa matenda ndi chifukwa chachikulu cha matenda obwera chifukwa cha kudya chifukwa cha kudya tizilombo toyambitsa matenda kapena poizoni wawo. Ku United States kokha, matenda obwera chifukwa cha kudya amayambitsa matenda pafupifupi 76 miliyoni, anthu 325,000 omwe amalowa m'chipatala, ndi anthu 5,000 amafa chaka chilichonse1. Kuphatikiza apo, Dipatimenti ya Ulimi ku United States (USDA) ikuyerekeza kuti kudya kwambiri zipatso zatsopano ndiko komwe kumayambitsa 48% ya matenda onse obwera chifukwa cha chakudya ku United States2. Mtengo wa matenda ndi imfa zomwe zimachitika chifukwa cha matenda obwera chifukwa cha chakudya ku United States ndi wokwera kwambiri, malinga ndi Centers for Disease Control and Prevention (CDC) pa ndalama zoposa US$15.6 biliyoni pachaka3.
Pakadali pano, njira zophera tizilombo toyambitsa matenda pogwiritsa ntchito mankhwala, ma radiation5 ndi kutentha6 kuti zitsimikizire kuti chakudya chili bwino nthawi zambiri zimachitika pamalo ochepa owongolera (CCPs) motsatira unyolo wopanga (nthawi zambiri akakolola ndi/kapena akamapakidwa) m'malo mopitirira muyeso. Chifukwa chake, zimakhala zosavuta kuipitsidwa ndi chakudya. 7. Kuwongolera bwino matenda obwera chifukwa cha chakudya ndi kuwonongeka kwa chakudya kumafuna njira zophera tizilombo zomwe zingagwiritsidwe ntchito ponseponse pa famu ndi tebulo pomwe zikuchepetsa kuwonongeka kwa chilengedwe komanso ndalama.
Posachedwapa, njira yolimbana ndi mabakiteriya yopanda mankhwala, yochokera ku nanotechnology, yapangidwa yomwe ingathe kuletsa mabakiteriya pamwamba ndi mlengalenga pogwiritsa ntchito ma nanostructures amadzi opangidwa (EWNS). EWNS idapangidwa pogwiritsa ntchito njira ziwiri zofanana, electrospray ndi water ionization (Chithunzi 1a). Kafukufuku wakale wasonyeza kuti EWNS ili ndi zinthu zapadera zakuthupi ndi zamoyo8,9,10. EWNS ili ndi avareji ya ma elekitironi 10 pa kapangidwe kalikonse ndipo kukula kwa nanoscale yapakati ya 25 nm (Chithunzi 1b,c)8,9,10. Kuphatikiza apo, electron spin resonance (ESR) yawonetsa kuti EWNS ili ndi mitundu yambiri ya reactive oxygen species (ROS), makamaka hydroxyl (OH•) ndi superoxide (O2-) radicals (Chithunzi 1c)8. EVNS imakhala mumlengalenga kwa nthawi yayitali ndipo imatha kugundana ndi tizilombo toyambitsa matenda tomwe timayimitsidwa mumlengalenga ndikupezeka pamwamba, kupereka ROS payload yawo ndikuyambitsa kuletsa tizilombo toyambitsa matenda (Chithunzi 1d). Kafukufuku woyambirirayu adawonetsanso kuti EWNS imatha kuyanjana ndi kuletsa mabakiteriya osiyanasiyana a gram-negative ndi gram-positive, kuphatikizapo mycobacteria, pamwamba ndi mlengalenga. Kusanthula kwa ma electron microscopy kunawonetsa kuti kuletsa kumeneku kunayambitsidwa ndi kusokonezeka kwa nembanemba ya selo. Kuphatikiza apo, kafukufuku wokhudza kupuma mwachangu wasonyeza kuti kuchuluka kwa EWNS sikuyambitsa kuwonongeka kwa mapapo kapena kutupa 8.
(a) Kupopera kwa electros kumachitika pamene magetsi amphamvu agwiritsidwa ntchito pakati pa chubu cha capillary chokhala ndi madzi ndi counter electrode. (b) Kugwiritsa ntchito mphamvu yapamwamba kumabweretsa zochitika ziwiri zosiyana: (i) kupopera madzi ndi electros (ii) kupanga mitundu ya okosijeni (ions) yomwe imagwidwa mu EWNS. (c) Kapangidwe kake kapadera ka EWNS. (d) Chifukwa cha kukula kwake kochepa, EWNS imayendayenda kwambiri ndipo imatha kuyanjana ndi tizilombo toyambitsa matenda touluka.
Kuthekera kwa nsanja ya EWNS yolimbana ndi mavairasi kuletsa tizilombo toyambitsa matenda tomwe timadya pamwamba pa chakudya chatsopano kwawonetsedwanso posachedwapa. Zawonetsedwanso kuti mphamvu ya pamwamba ya EWNS pamodzi ndi mphamvu yamagetsi ingagwiritsidwe ntchito kukwaniritsa cholinga chake. Kuphatikiza apo, zotsatira zoyambirira za tomato wachilengedwe pambuyo poti wapezeka pa EWNS ya mphindi 90 pa EWNS ya pafupifupi 50,000 #/cm3 zinali zolimbikitsa, ndipo tizilombo toyambitsa matenda osiyanasiyana tomwe timadya monga E. coli ndi Listeria 11 adawona. Kuphatikiza apo, mayeso oyamba a organoleptic sanawonetse zotsatirapo za kumva poyerekeza ndi tomato wowongolera. Ngakhale zotsatira zoyambirirazi zoletsa izi zimalimbikitsa kugwiritsa ntchito chitetezo cha chakudya ngakhale pamlingo wotsika kwambiri wa EWNS wa 50,000#/cc. onani, n'zoonekeratu kuti kuthekera kwakukulu koletsa kungakhale kopindulitsa kwambiri pochepetsa chiopsezo cha matenda ndi kuwonongeka.
Apa, tiyang'ana kwambiri kafukufuku wathu pakupanga nsanja yopanga EWNS kuti tithe kusintha bwino magawo a kapangidwe kake ndikuwongolera bwino mphamvu za fizikiki za EWNS kuti ziwonjezere mphamvu zawo zotsutsana ndi mabakiteriya. Makamaka, kukonza kwayang'ana kwambiri pakuwonjezera mphamvu zawo pamwamba (kuti ziwongolere kuperekedwa kolunjika) ndi kuchuluka kwa ROS (kuti ziwongolere bwino ntchito yoletsa kugwira ntchito). Fotokozani mphamvu za fizikiki-mankhwala (kukula, mphamvu ndi kuchuluka kwa ROS) pogwiritsa ntchito njira zamakono zowunikira ndikugwiritsa ntchito tizilombo toyambitsa matenda wamba monga E.
EVNS idapangidwa pogwiritsa ntchito ma elekitiroma nthawi imodzi komanso kuyika madzi oyera kwambiri (18 MΩ cm–1). Nebulizer yamagetsi 12 nthawi zambiri imagwiritsidwa ntchito popanga atomization ya zakumwa ndi kupanga tinthu ta polymer ndi ceramic 13 ndi ulusi 14 wa kukula kolamulidwa.
Monga momwe zafotokozedwera m'mabuku am'mbuyomu 8, 9, 10, 11, mu kuyesera kwachizolowezi, mphamvu yamagetsi yapamwamba idagwiritsidwa ntchito pakati pa capillary yachitsulo ndi electrode yotsutsana ndi nthaka. Panthawiyi, zochitika ziwiri zosiyana zimachitika: i) electrospray ndi ii) ionization yamadzi. Mphamvu yamagetsi yamphamvu pakati pa ma electrode awiriwa imayambitsa ma negative charges kuti akhazikike pamwamba pa madzi oundana, zomwe zimapangitsa kuti ma cones a Taylor apangidwe. Zotsatira zake, madontho amadzi okhala ndi mphamvu zambiri amapangidwa, omwe amapitilizabe kusweka kukhala tinthu tating'onoting'ono, monga momwe zilili mu chiphunzitso cha Rayleigh16. Nthawi yomweyo, minda yamagetsi yamphamvu imapangitsa mamolekyu ena amadzi kugawanika ndikuchotsa ma electron (ionize), zomwe zimapangitsa kuti pakhale kuchuluka kwa mitundu ya okosijeni yogwira ntchito (ROS)17. ROS18 yopangidwa nthawi imodzi idasungidwa mu EWNS (Chithunzi 1c).
Pa chithunzi 2a chikuwonetsa njira yopangira EWNS yomwe idapangidwa ndikugwiritsidwa ntchito mu kapangidwe ka EWNS mu kafukufukuyu. Madzi oyera omwe adasungidwa mu botolo lotsekedwa adalowetsedwa kudzera mu chubu cha Teflon (m'mimba mwake wamkati wa 2 mm) mu singano yachitsulo chosapanga dzimbiri ya 30G (capillary yachitsulo). Kuyenda kwa madzi kumayendetsedwa ndi kuthamanga kwa mpweya mkati mwa botolo, monga momwe zasonyezedwera pa Chithunzi 2b. Singanoyo imayikidwa pa console ya Teflon ndipo imatha kusinthidwa pamanja patali kuchokera ku counter electrode. Count electrode ndi disk ya aluminiyamu yopukutidwa yokhala ndi dzenje pakati kuti iperekedwe. Pansi pa counter electrode pali funnel ya aluminiyamu yotsanzira, yomwe imalumikizidwa ndi makina ena onse oyesera kudzera pa doko la sampling (Chithunzi 2b). Kuti tipewe kukwera kwa mphamvu komwe kungasokoneze ntchito ya sampling, zigawo zonse za sampling zimayikidwa pansi pamagetsi.
(a) Dongosolo Lopanga Mapangidwe a Madzi ndi Mapangidwe Atsopano (EWNS). (b) Gawo lodutsa la sampler ndi electrospray, kusonyeza magawo ofunikira kwambiri. (c) Kukhazikitsa koyesera kwa mabakiteriya kuti asagwire ntchito.
Dongosolo lopangira EWNS lomwe lafotokozedwa pamwambapa limatha kusintha magawo ofunikira ogwirira ntchito kuti lithandizire kusintha bwino kwa mawonekedwe a EWNS. Sinthani voltage yogwiritsidwa ntchito (V), mtunda pakati pa singano ndi counter electrode (L), ndi kuyenda kwa madzi (φ) kudzera mu capillary kuti musinthe mawonekedwe a EWNS. Chizindikiro chomwe chimagwiritsidwa ntchito kuyimira kuphatikiza kosiyanasiyana: [V (kV), L (cm)]. Sinthani kuyenda kwa madzi kuti mupeze cone yokhazikika ya Taylor ya seti inayake [V, L]. Pazifukwa za kafukufukuyu, m'mimba mwake wa aperture wa counter electrode (D) unasungidwa pa mainchesi 0.5 (1.29 cm).
Chifukwa cha geometry yochepa ndi asymmetry, mphamvu ya magetsi singathe kuwerengedwa kuchokera ku mfundo zoyambirira. M'malo mwake, pulogalamu ya QuickField™ (Svendborg, Denmark)19 idagwiritsidwa ntchito kuwerengera mphamvu yamagetsi. Mphamvu yamagetsi si yofanana, kotero mtengo wa mphamvu yamagetsi yomwe ili kumapeto kwa capillary idagwiritsidwa ntchito ngati mtengo wofotokozera mitundu yosiyanasiyana ya makonzedwe.
Pa kafukufukuyu, kuphatikiza kambiri kwa magetsi ndi mtunda pakati pa singano ndi counter electrode kunayesedwa malinga ndi kapangidwe ka Taylor cone, kukhazikika kwa Taylor cone, kukhazikika kwa kupanga kwa EWNS, ndi kuberekanso. Kuphatikiza kosiyanasiyana kwawonetsedwa mu Supplementary Table S1.
Zotsatira za dongosolo lopangira EWNS zidalumikizidwa mwachindunji ku Scanning Mobility Particle Size Analyzer (SMPS, Model 3936, TSI, Shoreview, MN) kuti muyeze kuchuluka kwa tinthu tating'onoting'ono, komanso ku Aerosol Faraday Electrometer (TSI, Model 3068B, Shoreview, MN). ) ya mafunde a aerosol zidayesedwa monga momwe tafotokozera m'buku lathu lapitalo. SMPS ndi aerosol electrometer zonse zidayesedwa pamlingo woyenda wa 0.5 L/min (kutuluka kwa chitsanzo chonse 1 L/min). Kuchuluka kwa tinthu tating'onoting'ono ndi kuyenda kwa aerosol kudayesedwa kwa masekondi 120. Muyesowu umabwerezedwa nthawi 30. Kutengera ndi muyeso wamakono, kuchuluka kwa aerosol kumawerengedwa ndipo kuchuluka kwapakati kwa EWNS kumayesedwa pa chiwerengero chonse cha tinthu ta EWNS tosankhidwa. Mtengo wapakati wa EWNS ukhoza kuwerengedwa pogwiritsa ntchito Equation (1):
kumene IEl ndiye mphamvu yoyezedwa, NSMPS ndiye kuchuluka kwa digito komwe kumayesedwa ndi SMPS, ndipo φEl ndiye kuchuluka kwa kayendedwe ka madzi pa electrometer iliyonse.
Popeza chinyezi (RH) chimakhudza mphamvu ya pamwamba, kutentha ndi (RH) sizinasinthe panthawi yoyeserayi pa 21°C ndi 45% motsatana.
Makina ojambulira a atomiki (AFM), Asylum MFP-3D (Asylum Research, Santa Barbara, CA) ndi AC260T probe (Olympus, Tokyo, Japan) zinagwiritsidwa ntchito poyesa kukula ndi moyo wa EWNS. Mafupipafupi a AFM scanning anali 1 Hz, malo ojambulira anali 5 μm × 5 μm, ndi mizere 256 scan. Zithunzi zonse zinayikidwa mu dongosolo loyamba la chithunzi pogwiritsa ntchito pulogalamu ya Asylum (mask range 100 nm, threshold 100 pm).
Funeli yoyesera inachotsedwa ndipo pamwamba pa mica inayikidwa pa mtunda wa 2.0 cm kuchokera ku counter electrode kwa nthawi yapakati ya masekondi 120 kuti tipewe kusonkhana kwa tinthu tating'onoting'ono ndi kupangika kwa madontho osakhazikika pamwamba pa mica. EWNS inapoperedwa mwachindunji pamwamba pa mica yodulidwa kumene (Ted Pella, Redding, CA). Chithunzi cha pamwamba pa mica nthawi yomweyo AFM itatulutsa madontho. Ngodya yolumikizana ya pamwamba pa mica yodulidwa kumene yosasinthidwa ili pafupi ndi 0°, kotero EVNS imagawidwa pamwamba pa mica mu mawonekedwe a dome. M'mimba mwake (a) ndi kutalika (h) kwa madontho ofalikira adayesedwa mwachindunji kuchokera ku AFM topography ndipo adagwiritsidwa ntchito kuwerengera voliyumu ya kufalikira kwa dome ya EWNS pogwiritsa ntchito njira yathu yotsimikiziridwa kale. Poganiza kuti EWNS yomwe ili m'bwalo ili ndi voliyumu yofanana, m'mimba mwake wofanana ukhoza kuwerengedwa pogwiritsa ntchito Equation (2):
Kutengera njira yomwe tidapanga kale, electron spin resonance (ESR) spin trap idagwiritsidwa ntchito kuzindikira kupezeka kwa ma radical intermediates afupiafupi mu EWNS. Ma aerosol adapangidwa kudzera mu 650 μm Midget sparger (Ace Glass, Vineland, NJ) yokhala ndi yankho la 235 mM la DEPMPO(5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide) (Oxis International Inc.). Portland, Oregon). Miyeso yonse ya ESR idachitika pogwiritsa ntchito Bruker EMX spectrometer (Bruker Instruments Inc. Billerica, MA, USA) ndi cell ya flat panel. Pulogalamu ya Acquisit (Bruker Instruments Inc. Billerica, MA, USA) idagwiritsidwa ntchito kusonkhanitsa ndikusanthula deta. Kuzindikira makhalidwe a ROS kunachitika kokha pazochitika zogwirira ntchito [-6.5 kV, 4.0 cm]. Kuchuluka kwa EWNS kudayesedwa pogwiritsa ntchito SMPS pambuyo powerengera kutayika kwa EWNS mu impactor.
Magawo a Ozone anayang'aniridwa pogwiritsa ntchito 205 Dual Beam Ozone Monitor™ (2B Technologies, Boulder, Co)8,9,10.
Pazinthu zonse za EWNS, mtengo wapakati umagwiritsidwa ntchito ngati mtengo woyezera, ndipo kupotoka kokhazikika kumagwiritsidwa ntchito ngati cholakwika choyezera. Mayeso a T adachitika kuti ayerekezere mtengo wa zinthu za EWNS zomwe zidakonzedwa bwino ndi mtengo wofanana wa EWNS yoyambira.
Chithunzi 2c chikuwonetsa njira yopangira ma electrostatic precipitation (EPES) yomwe idapangidwa kale komanso yodziwika bwino yomwe ingagwiritsidwe ntchito popereka ma EWNS pamwamba. EPES imagwiritsa ntchito ma EVNS charges omwe "angatsogoleredwe" mwachindunji pamwamba pa chandamale mothandizidwa ndi mphamvu yamagetsi yamphamvu. Tsatanetsatane wa njira ya EPES waperekedwa mu buku laposachedwa la Pyrgiotakis et al. 11. Chifukwa chake, EPES ili ndi chipinda cha PVC chosindikizidwa cha 3D chokhala ndi malekezero opindika ndipo chili ndi mbale ziwiri zachitsulo zosapanga dzimbiri (304 zosapanga dzimbiri, zophimbidwa ndi galasi) pakati pa 15.24 cm. Mabodiwo adalumikizidwa ku gwero lakunja lamagetsi apamwamba (Bertran 205B-10R, Spellman, Hauppauge, NY), mbale yapansi nthawi zonse inali yolumikizidwa ku magetsi abwino, ndipo mbale yapamwamba nthawi zonse inali yolumikizidwa pansi (nthaka yoyandama). Makoma a chipindacho ali ndi zojambulazo za aluminiyamu, zomwe zimakhala pansi pamagetsi kuti zisatayike tinthu. Chipindacho chili ndi chitseko chakutsogolo chotsekedwa chomwe chimalola malo oyesera kuti ayikidwe pazitsulo zapulasitiki zomwe zimawakweza pamwamba pa mbale yachitsulo yapansi kuti apewe kusokonezedwa ndi magetsi ambiri.
Kugwira ntchito bwino kwa EWNS mu EPES kunawerengedwa malinga ndi ndondomeko yomwe idapangidwa kale yomwe yafotokozedwa mu Chithunzi Chowonjezera S111.
Monga chipinda chowongolera, chipinda chachiwiri chozungulira cha cylindrical chinalumikizidwa motsatizana ku dongosolo la EPES, momwe fyuluta yapakati ya HEPA idagwiritsidwa ntchito kuchotsa EWNS. Monga momwe zasonyezedwera pa Chithunzi 2c, aerosol ya EWNS idapopedwa kudzera m'zipinda ziwiri zomangidwa mkati. Fyuluta pakati pa chipinda chowongolera ndi EPES imachotsa EWNS yotsalayo zomwe zimapangitsa kutentha komweko (T), chinyezi chofanana (RH) ndi kuchuluka kwa ozoni.
Zapezeka kuti tizilombo toyambitsa matenda tomwe timapezeka m'zakudya timawononga zakudya zatsopano monga E. coli (ATCC #27325), fecal indicator, Salmonella enterica (ATCC #53647), tizilombo toyambitsa matenda tomwe timapezeka m'zakudya, Listeria wopanda vuto (ATCC #33090), cholowa m'malo mwa Listeria monocytogenes yoyambitsa matenda, yochokera ku ATCC (Manassas, VA) Saccharomyces cerevisiae (ATCC #4098), cholowa m'malo mwa yisiti yoonongeka, komanso bakiteriya wosagwira ntchito, Mycobacterium paralucky (ATCC #19686).
Gulani mabokosi a tomato wamphesa zachilengedwe kuchokera kumsika wanu wapafupi ndikusunga mufiriji pa 4°C mpaka mutagwiritsa ntchito (mpaka masiku atatu). Tomato woyesera onse anali ofanana kukula, pafupifupi 1/2 inchi m'mimba mwake.
Njira zochizira matenda, kubayidwa, kufalikira, ndi kuchuluka kwa koloni zafotokozedwa mwatsatanetsatane m'buku lathu lapitalo ndipo zafotokozedwa mwatsatanetsatane mu Supplementary Data. Kugwira ntchito kwa EWNS kunayesedwa poika tomato wothiridwa mu 40,000 #/cm3 kwa mphindi 45. Mwachidule, tomato atatu adagwiritsidwa ntchito poyesa tizilombo tomwe tinapulumuka panthawi ya t = 0 min. Tomato atatu adayikidwa mu EPES ndipo adayikidwa mu EWNS pa 40,000 #/cc (tomato wothiridwa mu EWNS) ndipo atatu otsalawo adayikidwa mu chipinda chowongolera (tomato wowongolera). Kukonza kwina kwa tomato m'magulu onse awiri sikunachitike. Tomato wothiridwa mu EWNS ndi tomato wowongolera adachotsedwa patatha mphindi 45 kuti awone momwe EWNS imakhudzira.
Kuyesera kulikonse kunachitika katatu. Kusanthula deta kunachitika motsatira ndondomeko yomwe yafotokozedwa mu Supplementary Data.
Njira zoletsa kufalikira kwa tizilombo toyambitsa matenda zinayesedwa pogwiritsa ntchito njira zothira madzi kuchokera ku zitsanzo za EWNS zomwe zawonekera (mphindi 45 pa 40,000 #/cm3 EWNS aerosol concentration) ndi zitsanzo zosayatsidwa ndi mabakiteriya osavulaza E. coli, Salmonella enterica ndi Lactobacillus. Tinthu tating'onoting'ono tinakhazikika mu 2.5% glutaraldehyde, 1.25% paraformaldehyde ndi 0.03% picric acid mu 0.1 M sodium cacodylate buffer (pH 7.4) kwa maola awiri kutentha kwa chipinda. Mukatsuka, sungani ndi 1% osmium tetroxide (OsO4)/1.5% potassium ferrocyanide (KFeCN6) kwa maola awiri, sambani katatu m'madzi ndikuyika mu 1% uranyl acetate kwa ola limodzi, kenako sambani kawiri m'madzi, kenako pukutani madzi kwa mphindi 10 mu 50%, 70%, 90%, 100% mowa. Kenako zitsanzozo zinayikidwa mu propylene oxide kwa ola limodzi ndipo zinalowetsedwa ndi chisakanizo cha 1:1 cha propylene oxide ndi TAAP Epon (Marivac Canada Inc. St. Laurent, CA). Zitsanzozo zinayikidwa mu TAAB Epon ndipo zinasinthidwa kukhala polymer pa 60°C kwa maola 48. Utomoni wophikidwawo unadulidwa ndi kuwonedwa ndi TEM pogwiritsa ntchito microscope yamagetsi yotumizira JEOL 1200EX (JEOL, Tokyo, Japan) yokhala ndi kamera ya AMT 2k CCD (Advanced Microscopy Techniques, Corp., Woburn, Massachusetts, USA).
Kuyesera konse kunachitika katatu. Pa nthawi iliyonse, kutsuka kwa bakiteriya kunabzalidwa katatu, zomwe zinapangitsa kuti pakhale mfundo zisanu ndi zinayi za deta pa mfundo iliyonse, ndipo avareji yake imagwiritsidwa ntchito ngati kuchuluka kwa bakiteriya pa tizilombo toyambitsa matenda. Kupatuka kwa muyezo kunagwiritsidwa ntchito ngati cholakwika choyezera. Kuwerengera kwa mfundo zonse.
Logarithm ya kuchepa kwa kuchuluka kwa mabakiteriya poyerekeza ndi t = 0 min idawerengedwa pogwiritsa ntchito njira iyi:
kumene C0 ndi kuchuluka kwa mabakiteriya omwe ali mu chitsanzo chowongolera pa nthawi ya 0 (mwachitsanzo, pamwamba pauma koma asanaikidwe m'chipinda) ndipo Cn ndi kuchuluka kwa mabakiteriya pamwamba patatha mphindi n kuchokera pamene akhudzidwa.
Pofuna kufotokozera kuwonongeka kwachilengedwe kwa mabakiteriya panthawi yomwe adakumana ndi mabakiteriya kwa mphindi 45, kuchepetsa kwa log poyerekeza ndi kuwongolera pambuyo pa mphindi 45 kunawerengedwanso motere:
kumene Cn ndi kuchuluka kwa mabakiteriya mu chitsanzo chowongolera pa nthawi n ndipo Cn-Control ndi kuchuluka kwa mabakiteriya owongolera pa nthawi n. Deta imaperekedwa ngati kuchepetsa kwa log poyerekeza ndi kulamulira (palibe kukhudzana ndi EWNS).
Pa kafukufukuyu, kuphatikiza kambiri kwa magetsi ndi mtunda pakati pa singano ndi counter electrode kunayesedwa malinga ndi kapangidwe ka Taylor cone, kukhazikika kwa Taylor cone, kukhazikika kwa kupanga EWNS, ndi kuberekanso. Kuphatikiza kosiyanasiyana kwawonetsedwa mu Supplementary Table S1. Milandu iwiri yowonetsa makhalidwe okhazikika ndi kuberekanso (Taylor cone, kupanga EWNS, ndi kukhazikika pakapita nthawi) idasankhidwa kuti iphunzire mokwanira. Pa chithunzi. Chithunzi 3 chikuwonetsa zotsatira za mphamvu, kukula, ndi zomwe zili mu ROS m'milandu yonse iwiri. Zotsatira zake zafotokozedwanso mwachidule mu Table 1. Kuti ziwonekere, Chithunzi 3 ndi Table 1 zonse zikuphatikiza makhalidwe a EWNS8, 9, 10, 11 yomwe idapangidwa kale (baseline-EWNS). Kuwerengera kufunika kwa ziwerengero pogwiritsa ntchito mayeso a t-tailed awiri kwasindikizidwanso mu Supplementary Table S2. Kuphatikiza apo, deta yowonjezera ikuphatikiza maphunziro a zotsatira za counter electrode sampling hole diameter (D) ndi mtunda pakati pa ground electrode ndi nsonga (L) (Zithunzi Zowonjezera S2 ndi S3).
(ac) Kugawa kukula komwe kumayesedwa ndi AFM. (df) Kakhalidwe ka mphamvu ya pamwamba. (g) Kufotokozera kwa ROS kwa EPR.
Ndikofunikanso kudziwa kuti pazochitika zonse zomwe zili pamwambapa, mphamvu ya ionization yomwe inayesedwa inali pakati pa 2 ndi 6 μA ndipo mphamvu yamagetsi inali pakati pa -3.8 ndi -6.5 kV, zomwe zinapangitsa kuti mphamvu yamagetsi igwiritsidwe ntchito yosakwana 50 mW pa gawo limodzi lolumikizirana la EWNS. Ngakhale kuti EWNS idapangidwa pansi pa kupanikizika kwakukulu, kuchuluka kwa ozoni kunali kochepa kwambiri, kosapitirira 60 ppb.
Chithunzi Chowonjezera S4 chikuwonetsa minda yamagetsi yoyeserera ya zochitika za [-6.5 kV, 4.0 cm] ndi [-3.8 kV, 0.5 cm], motsatana. Pa zochitika za [-6.5 kV, 4.0 cm] ndi [-3.8 kV, 0.5 cm], mawerengedwe a minda ndi 2 × 105 V/m ndi 4.7 × 105 V/m, motsatana. Izi zikuyembekezeredwa, popeza pankhaniyi yachiwiri chiŵerengero cha mtunda wamagetsi ndi chachikulu kwambiri.
Pa chithunzi 3a,b chikuwonetsa kukula kwa EWNS komwe kunayesedwa ndi AFM8. Ma diameter apakati a EWNS omwe anawerengedwa anali 27 nm ndi 19 nm pa ma scheme a [-6.5 kV, 4.0 cm] ndi [-3.8 kV, 0.5 cm], motsatana. Pa zochitika za [-6.5 kV, 4.0 cm] ndi [-3.8 kV, 0.5 cm], kusintha kwa geometric standard kwa ma distributions ndi 1.41 ndi 1.45, motsatana, kusonyeza kugawa kocheperako kwa kukula. Kukula kwapakati ndi kusintha kwa geometric standard zonse zili pafupi kwambiri ndi EWNS yoyambira, pa 25 nm ndi 1.41, motsatana. Pa chithunzi 3c chikuwonetsa kugawa kwa kukula kwa EWNS yoyambira yomwe inayesedwa pogwiritsa ntchito njira yomweyo pansi pa mikhalidwe yomweyi.
Pa chithunzi cha 3d,e chikuwonetsa zotsatira za kufotokozedwa kwa mphamvu. Deta ndi miyeso yapakati ya miyeso 30 yofanana ya kuchuluka (#/cm3) ndi mphamvu yamagetsi (I). Kusanthula kukuwonetsa kuti mphamvu yapakati pa EWNS ndi 22 ± 6 e- ndi 44 ± 6 e- ya [-6.5 kV, 4.0 cm] ndi [-3.8 kV, 0.5 cm], motsatana. Ali ndi mphamvu zapamwamba kwambiri poyerekeza ndi EWNS yoyambira (10 ± 2 e-), yayikulu kawiri kuposa [-6.5 kV, 4.0 cm] komanso yayikulu kanayi kuposa [-3 .8 kV, 0.5 cm]. Chithunzi cha 3f chikuwonetsa deta ya mphamvu ya Baseline-EWNS.
Kuchokera pamapu a kuchuluka kwa EWNS nambala (Zithunzi Zowonjezera S5 ndi S6), zitha kuwoneka kuti [-6.5 kV, 4.0 cm] ili ndi tinthu tambiri kuposa [-3.8 kV, 0.5 cm]. Ndikofunikiranso kudziwa kuti kuchuluka kwa EWNS nambala kunayang'aniridwa mpaka maola 4 (Zithunzi Zowonjezera S5 ndi S6), pomwe kukhazikika kwa mibadwo ya EWNS kunawonetsa milingo yofanana ya kuchuluka kwa tinthu m'zochitika zonse ziwiri.
Pa chithunzi 3g chikuwonetsa EPR spectrum pambuyo pochotsa optimized EWNS control (background) pa [-6.5 kV, 4.0 cm]. Ma ROS spectra adayerekezeredwanso ndi Baseline-EWNS scenario mu ntchito yofalitsidwa kale. Chiwerengero cha EWNS chomwe chimagwira ntchito ndi spin traps chinawerengedwa kukhala 7.5 × 104 EWNS/s, chomwe chikufanana ndi Baseline-EWNS8 yomwe idasindikizidwa kale. Ma EPR spectra adawonetsa bwino kukhalapo kwa mitundu iwiri ya ROS, pomwe O2- ndi mtundu waukulu ndipo OH• ndi wochepa. Kuphatikiza apo, kufananiza mwachindunji kwa mphamvu yayikulu kunawonetsa kuti EWNS yokonzedwanso inali ndi ROS yochuluka kwambiri poyerekeza ndi EWNS yoyambira.
Pa chithunzi 4 chikuwonetsa momwe EWNS imagwirira ntchito bwino mu EPES. Detayo yafotokozedwanso mwachidule mu Table 1 ndipo imayerekezeredwa ndi deta yoyambirira ya EWNS. Pa milandu yonse iwiri ya EUNS, kuyikako kuli pafupi ndi 100% ngakhale pa voltage yotsika ya 3.0 kV. Kawirikawiri, 3.0 kV ndi yokwanira kuyikako 100%, mosasamala kanthu za kusintha kwa mphamvu ya pamwamba. Pansi pa mikhalidwe yomweyi, mphamvu ya Baseline-EWNS inali 56% yokha chifukwa cha kuyikako kotsika (avereji ya ma elekitironi 10 pa EWNS iliyonse).
Pa chithunzi 5 ndi patebulo 2 chikufotokoza mwachidule kufunika kwa tizilombo toyambitsa matenda tomwe timayikidwa pamwamba pa phwetekere titayikidwa pa EWNS pafupifupi 40,000 #/cm3 kwa mphindi 45 pamlingo woyenera [-6.5 kV, 4.0 cm]. E. coli ndi Lactobacillus innocuous zoyikidwa mu incubated zinawonetsa kuchepa kwakukulu kwa mitengo 3.8 panthawi yomwe zimayikidwa mu incubated kwa mphindi 45. Pansi pa mikhalidwe yomweyi, S. enterica inali ndi kuchepa kwa mitengo 2.2, pomwe S. cerevisiae ndi M. parafortutum zinali ndi kuchepa kwa mitengo 1.0.
Ma electron micrograph (Chithunzi 6) akuwonetsa kusintha kwa thupi komwe kumachitika chifukwa cha EWNS pa maselo osavulaza a Escherichia coli, Streptococcus, ndi Lactobacillus zomwe zidapangitsa kuti asagwire ntchito. Mabakiteriya olamulira anali ndi nembanemba ya maselo yomwe inali isanagwire ntchito, pomwe mabakiteriya omwe adawonekera adawononga nembanemba yakunja.
Kujambula zithunzi za ma elekitironi ndi mabakiteriya owonekera kunawonetsa kuwonongeka kwa nembanemba.
Deta yokhudza makhalidwe a physicochemical a EWNS optimized pamodzi ikuwonetsa kuti makhalidwe (surface charge ndi ROS content) a EWNS adakula kwambiri poyerekeza ndi deta yoyambira ya EWNS yomwe idasindikizidwa kale8,9,10,11. Kumbali ina, kukula kwawo kunakhalabe mu nanometer range, yofanana kwambiri ndi zotsatira zomwe zidanenedwa kale, zomwe zimawalola kukhalabe mlengalenga kwa nthawi yayitali. Kufalikira kwa polygonal komwe kumawoneka kumatha kufotokozedwa ndi kusintha kwa mphamvu ya pamwamba komwe kumatsimikiza kukula kwa EWNS, kusakhazikika kwa Rayleigh effect, ndi coalescence yomwe ingatheke. Komabe, monga momwe Nielsen et al. 22 adafotokozera, mphamvu yayikulu ya pamwamba imachepetsa kuuluka mwa kuwonjezera mphamvu/kupsinjika kwa madzi pamwamba. Mu buku lathu lapitalo8 chiphunzitsochi chidatsimikiziridwa mwachiyeso cha ma microdroplets 22 ndi EWNS. Kutayika kwa mphamvu panthawi yowonjezera kungakhudzenso kukula ndikuthandizira kugawa kwa kukula komwe kwawonedwa.
Kuphatikiza apo, mphamvu pa kapangidwe kalikonse ndi pafupifupi 22-44 e-, kutengera momwe zinthu zilili, zomwe ndi zapamwamba kwambiri poyerekeza ndi EWNS yoyambira, yomwe ili ndi mphamvu yapakati ya ma elekitironi 10 ± 2 pa kapangidwe kalikonse. Komabe, ziyenera kudziwika kuti iyi ndi mphamvu yapakati ya EWNS. Seto et al. Zawonetsedwa kuti mphamvuyo ndi yosagwirizana ndipo imatsatira kugawa kwa log-normal21. Poyerekeza ndi ntchito yathu yapitayi, kuwirikiza kawiri mphamvu ya pamwamba kumawirikiza kawiri mphamvu ya deposition mu dongosolo la EPES kufika pafupifupi 100%11.