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Posachedwapa, nsanja yopanda mankhwala yolimbana ndi mavairasi yochokera ku nanotechnology pogwiritsa ntchito ma nanostructures amadzi opangidwa (EWNS) yapangidwa. EWNS ili ndi mphamvu yapamwamba pamwamba ndipo ili ndi mitundu yambiri ya okosijeni (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 kapangidwe kake. Kufotokozera kwa mawonekedwe a EWNS (mphamvu, kukula, ndi kuchuluka kwa ROS) kunachitika pogwiritsa ntchito njira zamakono zowunikira. Kuphatikiza apo, tizilombo toyambitsa matenda monga Escherichia coli, Salmonella enterica, Listeria innocua, Mycobacterium para fortitum, ndi Saccharomyces cerevisiae zidayikidwa pamwamba pa tomato wamphesa wachilengedwe kuti ziwunikire mphamvu zawo zoletsa mabakiteriya. Zotsatira zomwe zaperekedwa pano zikuwonetsa kuti mawonekedwe a EWNS amatha kusinthidwa bwino panthawi yopanga, zomwe zimapangitsa kuti pakhale kuwonjezeka kwakukulu kwa mphamvu yoletsa. Makamaka, mphamvu ya pamwamba inakwera ndi kasanu, ndipo kuchuluka kwa ROS kunakwera. Kuchuluka kwa mabakiteriya ochotsedwa kumadalira mabakiteriya ndipo kunayambira pa 1.0 mpaka 3.8 log pambuyo pa mphindi 45 kuchokera pamene anakhudzidwa ndi mlingo wa aerosol wa 40,000 #/cm3 EWNS.
Kuipitsidwa ndi tizilombo toyambitsa matenda ndi chifukwa chachikulu cha matenda obwera chifukwa cha kudya chifukwa cha kudya tizilombo toyambitsa matenda kapena poizoni wawo. Matenda obwera chifukwa cha kudya ndi omwe amachititsa matenda pafupifupi 76 miliyoni, kugonekedwa m'chipatala 325,000, ndi kufa 5,000 chaka chilichonse ku United States kokha1. Kuphatikiza apo, Dipatimenti ya Zaulimi ku United States (USDA) ikuyerekeza kuti kudya kwambiri zipatso zatsopano ndiko komwe kumachititsa 48 peresenti ya matenda onse obwera chifukwa cha chakudya omwe amanenedwa ku United States2. Mtengo wa matenda ndi imfa 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 ma thermal6 kuti zitsimikizire kuti chakudya chili bwino zimagwiritsidwa ntchito makamaka pamalo ochepa owongolera (CCPs) mu unyolo wopanga (nthawi zambiri akakolola ndi/kapena akamapakidwa) m'malo mopitilira kugwiritsidwa ntchito mwanjira yoti zipatso zatsopano zitha kuipitsidwa ndi zinthu zina. 7. Njira zophera tizilombo toyambitsa matenda zimafunika kuti zithetse bwino matenda obwera chifukwa cha chakudya komanso kuwonongeka kwa chakudya ndipo zitha kugwiritsidwa ntchito pa famu yonse. Zotsatira zochepa komanso mtengo wotsika.
Posachedwapa, nsanja yopanda mankhwala yochokera ku nanotechnology yapangidwa kuti ichepetse mabakiteriya pamwamba ndi mlengalenga pogwiritsa ntchito ma nanostructures amadzi opangidwa (EWNS). Pakupanga EVNS, njira ziwiri zofanana zinagwiritsidwa ntchito: electrospray ndi water ionization (Chithunzi 1a). EWNS yawonetsedwa kale kuti ili ndi zinthu zapadera zakuthupi ndi zamoyo8,9,10. EWNS ili ndi avareji ya ma electron 10 pa kapangidwe kalikonse ndipo kukula kwa nanometer yapakati pa 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. EWNS inakhalabe mlengalenga kwa nthawi yayitali ndipo imatha kugundana ndi ma microbes omwe amapachikidwa mlengalenga ndikupezeka pamwamba, kupereka ROS yawo yolipira ndikuyambitsa kuletsa ma microorganism (Chithunzi 1d). Kafukufuku wakaleyu adawonetsanso kuti EWNS imatha kuyanjana ndi kuletsa mabakiteriya osiyanasiyana opanda gramu ndi gramu omwe ndi ofunika paumoyo wa anthu, kuphatikizapo mycobacteria, pamwamba ndi mumlengalenga8,9. Microscopy ya ma electron yotumizira inawonetsa kuti kuletsa kumeneku kunayamba chifukwa cha kusokonekera kwa nembanemba ya selo. Kuphatikiza apo, kafukufuku wokhudza kupuma mwadzidzidzi wasonyeza kuti kuchuluka kwa EWNS sikuyambitsa kuwonongeka kwa mapapo kapena kutupa8.
(a) Kupopera kwa electros kumachitika pamene magetsi amphamvu agwiritsidwa ntchito pakati pa madzi okhala ndi capillary ndi counter electrode. (b) Kugwiritsa ntchito magetsi amphamvu kumabweretsa zochitika ziwiri zosiyana: (i) kupopera madzi ndi electrode (ii) kupanga mitundu ya okosijeni (ions) yomwe imagwidwa mu EWNS. (c) Kapangidwe kapadera ka EWNS. (d) EWNS imayendayenda kwambiri chifukwa cha kukula kwake kochepa 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 ingagwiritsidwe ntchito limodzi ndi mphamvu yamagetsi kuti iperekedwe molunjika. Chofunika kwambiri, zotsatira zoyambirira zabwino za kuchepa kwa pafupifupi 1.4 log mu ntchito ya phwetekere yachilengedwe motsutsana ndi tizilombo toyambitsa matenda osiyanasiyana monga E. coli ndi Listeria zidawonedwa mkati mwa mphindi 90 kuchokera pamene EWNS idakumana ndi EWNS pamlingo wa pafupifupi 50,000#/cm311. Kuphatikiza apo, mayeso oyamba a organoleptic kuwunika sanawonetse zotsatira za organoleptic poyerekeza ndi phwetekere yolamulira. Ngakhale kuti zotsatira zoyambirira izi zoletsa kudya zimalonjeza chitetezo cha chakudya ngakhale pamlingo wotsika kwambiri wa EWNS wa 50,000#/cc. onani, n'zoonekeratu kuti kuthekera kwakukulu kwa kuletsa kudya kungakhale kopindulitsa kwambiri pochepetsa chiopsezo cha matenda ndi kuwonongeka.
Apa, tiyang'ana kwambiri kafukufuku wathu pakupanga nsanja yopanga EWNS kuti tikonze bwino magawo a kapangidwe kake ndikuwonjezera mphamvu ya fizikiki ya EWNS kuti iwonjezere mphamvu yake yolimbana ndi mabakiteriya. Makamaka, kukonza bwino kwayang'ana kwambiri pakuwonjezera mphamvu yawo pamwamba (kukweza kuperekedwa kolunjika) ndi kuchuluka kwa ROS (kukweza mphamvu yoletsa kugwira ntchito). Kufotokozera bwino mphamvu ya fizikiki-mankhwala (kukula, mphamvu ndi kuchuluka kwa ROS) pogwiritsa ntchito njira zamakono zowunikira komanso kugwiritsa ntchito tizilombo toyambitsa matenda wamba monga E. coli, S. enterica, L. innocua, S. cerevisiae ndi M. parafortuitum.
EVNS idapangidwa pogwiritsa ntchito electrospray nthawi imodzi komanso ionization ya madzi oyera kwambiri (18 MΩ cm–1). Atomizer yamagetsi 12 nthawi zambiri imagwiritsidwa ntchito kupangira atomi yamadzimadzi ndi ma polymer opangidwa ndi tinthu ta 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 imagwiritsidwa ntchito pakati pa capillary yachitsulo ndi electrode yotsutsana ndi nthaka. Panthawiyi, zochitika ziwiri zosiyana zimachitika: 1) electrospray ndi 2) ionization ya madzi. 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 omwe ali ndi mphamvu zambiri amapangidwa, omwe amapitilizabe kusweka kukhala tinthu tating'onoting'ono, malinga ndi chiphunzitso cha Rayleigh16. Nthawi yomweyo, mphamvu yamagetsi yamphamvu imapangitsa kuti mamolekyu ena amadzi agawikane ndikuchotsa ma electron (ionization), motero amapanga mitundu yambiri ya reactive oxygen (ROS)17. Mapaketi a ROS18 opangidwa nthawi imodzi adasungidwa mu EWNS (Chithunzi 1c).
Pa chithunzi 2a chikuwonetsa njira yopangira EWNS yomwe idapangidwa ndikugwiritsidwa ntchito popanga EWNS mu kafukufukuyu. Madzi oyera omwe adasungidwa mu botolo lotsekedwa adaperekedwa kudzera mu chubu cha Teflon (m'mimba mwake wamkati wa 2 mm) kupita ku singano yachitsulo chosapanga dzimbiri ya 30G (capillary yachitsulo). Monga momwe zasonyezedwera pa Chithunzi 2b, kuyenda kwa madzi kumayendetsedwa ndi kuthamanga kwa mpweya mkati mwa botolo. Singanoyo imalumikizidwa ku console ya Teflon yomwe ingasinthidwe pamanja patali kuchokera ku counter electrode. Count electrode ndi disk yopukutidwa ya aluminiyamu yokhala ndi dzenje pakati kuti iperekedwe. Pansi pa counter electrode pali funnel ya aluminiyamu, yomwe imalumikizidwa ndi makina ena onse oyesera kudzera pa doko la sampling (Chithunzi 2b). Zigawo zonse za sampling zimayikidwa pansi pamagetsi kuti zipewe kukwera kwa mphamvu komwe kungawononge kusampling kwa tinthu tating'onoting'ono.
(a) Dongosolo Lopanga Mapangidwe a Madzi ndi Mapangidwe Atsopano (EWNS). (b) Gawo lozungulira la sampler ndi electrospray unit lomwe likuwonetsa 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. Zizindikiro [V (kV), L (cm)] zimagwiritsidwa ntchito kusonyeza kuphatikiza kosiyanasiyana. Sinthani kuyenda kwa madzi kuti mupeze Taylor cone yokhazikika ya seti inayake [V, L]. Pazifukwa za kafukufukuyu, kutsegula kwa counter electrode (D) kunayikidwa 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 ndi Scanning Mobility Particle Sizer (SMPS, model 3936, TSI, Shoreview, Minnesota) kuti ziyeze kuchuluka kwa tinthu tating'onoting'ono ndipo zidagwiritsidwa ntchito ndi electrometer ya Faraday aerosol (TSI, model 3068B, Shoreview, USA). MN) kuti ziyeze kuyenda kwa aerosol, monga tafotokozera m'nkhani yathu yapitayi9. SMPS ndi electrometer ya aerosol zonse zidatengedwa pamlingo woyenda wa 0.5 L/min (kuchuluka kwa chitsanzo 1 L/min). Kuchuluka kwa tinthu tating'onoting'ono ndi fluxes ya aerosol zidayesedwa kwa masekondi 120. Bwerezani muyesowo nthawi 30. Mtengo wonse wa aerosol umawerengedwa kuchokera ku muyeso wamakono, ndipo mtengo wapakati wa EWNS umawerengedwa kuchokera ku chiwerengero chonse cha tinthu ta EWNS totengedwa. Mtengo wapakati wa EWNS ukhoza kuwerengedwa pogwiritsa ntchito Equation (1):
kumene IEl ndiye mphamvu yoyezedwa, NSMPS ndiye kuchuluka kwa manambala komwe kumayesedwa ndi SMPS, ndipo φEl ndiye kuchuluka kwa kayendedwe ka madzi kupita ku electrometer.
Popeza chinyezi (RH) chimakhudza mphamvu ya pamwamba, kutentha ndi (RH) sizinasinthe pa 21°C ndi 45%, motsatana, panthawi yoyesera.
Makina ojambulira mphamvu ya atomiki (AFM), Asylum MFP-3D (Asylum Research, Santa Barbara, CA) ndi AC260T probe (Olympus, Tokyo, Japan) zinagwiritsidwa ntchito poyesa kukula ndi moyo wa EWNS. Chiŵerengero cha AFM scan ndi 1 Hz ndipo malo ojambulira ndi 5 µm×5 µm okhala ndi mizere 256 yojambulira. Zithunzi zonse zinayikidwa mu dongosolo loyamba la chithunzi pogwiritsa ntchito pulogalamu ya Asylum (chigoba chokhala ndi mtunda wa 100 nm ndi malire a 100 pm).
Chotsani njira yoyezera zitsanzo ndikuyika pamwamba pa mica pa mtunda wa 2.0 cm kuchokera ku counter electrode kwa nthawi yapakati ya masekondi 120 kuti mupewe kuphatikizana kwa tinthu tating'onoting'ono ndi kupanga madontho osakhazikika pamwamba pa mica. EWNS idayikidwa mwachindunji pamalo odulidwa kumene a mica (Ted Pella, Redding, CA). Nthawi yomweyo atatulutsa madzi, pamwamba pa mica idawonetsedwa pogwiritsa ntchito AFM. Ngodya yolumikizira pamwamba pa mica yodulidwa kumene yosasinthidwa ili pafupi ndi 0°, kotero EWNS imafalikira pamwamba pa mica mu mawonekedwe a domed20. M'mimba mwake (a) ndi kutalika (h) kwa madontho ofalikira adayesedwa mwachindunji kuchokera ku AFM topography ndipo adagwiritsidwa ntchito kuwerengera voliyumu ya domed diffusion EWNS pogwiritsa ntchito njira yathu yovomerezeka kale8. Poganiza kuti EVNS yomwe ili mkati mwake ili ndi voliyumu yofanana, m'mimba mwake wofanana ukhoza kuwerengedwa kuchokera ku equation (2):
Mogwirizana ndi njira yomwe tidapanga kale, electron spin resonance (ESR) spin trap idagwiritsidwa ntchito kuzindikira kupezeka kwa ma radical intermediates afupiafupi mu EWNS. Ma Aerosol adadutsa mu yankho lomwe lili ndi 235 mM DEPMPO (5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide) (Oxis International Inc., Portland, Oregon). Kuyeza konse kwa EPR kudachitika pogwiritsa ntchito Bruker EMX spectrometer (Bruker Instruments Inc. Billerica, MA, USA) ndi ma flat cell arrays. Pulogalamu ya Acquisit (Bruker Instruments Inc. Billerica, MA, USA) idagwiritsidwa ntchito kusonkhanitsa ndikusanthula deta. Kufotokozera kwa ROS kudachitika kokha pazikhalidwe zogwirira ntchito [-6.5 kV, 4.0 cm]. Kuchuluka kwa EWNS kudayesedwa pogwiritsa ntchito SMPS mutaganizira kutayika kwa EWNS mu impactor.
Magawo a Ozone anayang'aniridwa pogwiritsa ntchito 205 Dual Beam Ozone Monitor™ (2B Technologies, Boulder, Co)8,9,10.
Pa zinthu zonse za EWNS, mtengo woyezera ndi avereji ya muyeso, ndipo cholakwika choyezera ndi kupotoka kokhazikika. Kuyesa kwa t kunachitika kuti kuyerekezere mtengo wa chizindikiro cha EWNS chokonzedwa bwino ndi mtengo wofanana wa EWNS yoyambira.
Chithunzi 2c chikuwonetsa Electrostatic Precipitation Pass Through System (EPES) yomwe idapangidwa kale komanso yodziwika bwino yomwe ingagwiritsidwe ntchito kulunjika EWNS11 pamalo. EPES imagwiritsa ntchito EWNS charge pamodzi ndi mphamvu yamagetsi yamphamvu kuti "iloze" mwachindunji pamwamba pa chandamale. Tsatanetsatane wa makina a 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 okhala ndi zitsulo ziwiri zosapanga dzimbiri (304 zosapanga dzimbiri, zopukutidwa ndi galasi) pakati pa 15.24 cm. Mabolodiwo adalumikizidwa ku gwero lakunja lamagetsi apamwamba (Bertran 205B-10R, Spellman, Hauppauge, NY), bolodi lapansi nthawi zonse linali labwino ndipo bolodi lapamwamba nthawi zonse linkakhala pansi (loyandama). Makoma a chipindacho ali ndi zojambulazo za aluminiyamu, zomwe zimakhala pansi pamagetsi kuti tipewe kutayika kwa tinthu. Chipindacho chili ndi chitseko chakutsogolo chotsekedwa chomwe chimalola malo oyesera kuyikidwa pa racks zapulasitiki, ndikuzichotsa pa mbale yachitsulo yapansi kuti tipewe 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, kuyenda kwachiwiri kudzera mu chipinda chozungulira kumalumikizidwa motsatizana ndi dongosolo la EPES pogwiritsa ntchito fyuluta yapakati ya HEPA kuti ichotse EWNS. Monga momwe zasonyezedwera pachithunzi 2c, aerosol ya EWNS idapopedwa kudzera m'zipinda ziwiri zolumikizidwa motsatizana. 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 zipatso zatsopano monga Escherichia coli (ATCC #27325), chizindikiro cha ndowe, Salmonella enterica (ATCC #53647), tizilombo toyambitsa matenda tomwe timapezeka m'zakudya, Listeria innocua (ATCC #33090), njira ina m'malo mwa Listeria monocytogenes. , Saccharomyces cerevisiae (ATCC #4098) monga njira ina m'malo mwa yisiti yowononga, ndi Mycobacterium parafortuitous (ATCC #19686) ngati mabakiteriya amoyo omwe amalimbana ndi matenda adagulidwa ku ATCC (Manassas, Virginia).
Gulani mabokosi a tomato wamphesa wosagwiritsidwa ntchito mwachisawawa kumsika wanu wapafupi ndipo muwasunge mufiriji pa 4°C mpaka mutagwiritsa ntchito (mpaka masiku atatu). Sankhani tomato kuti muyesere kukula kwake, pafupifupi 1/2 inchi m'mimba mwake.
Njira zoyendetsera kuyika, kuyamwitsa, kufalikira kwa matenda ndi kuwerengera koloni zafotokozedwa mwatsatanetsatane m'mabuku athu am'mbuyomu ndipo zafotokozedwa mwatsatanetsatane mu Supplementary Data 11. Kugwira ntchito kwa EWNS kunayesedwa poika tomato wothira mu 40,000 #/cm3 kwa mphindi 45. Mwachidule, panthawi ya t = 0 min, tomato atatu adagwiritsidwa ntchito poyesa tizilombo toyambitsa matenda tomwe tinatsala. Tomato atatu adayikidwa mu EPES ndipo adayikidwa mu EWNS pa 40,000 #/cc (tomato wothira mu EWNS) ndipo ena atatu adayikidwa mu chipinda chowongolera (tomato wowongolera). Palibe gulu la tomato lomwe lidakonzedwanso. Tomato ndi zowongolera zomwe zidapezeka mu EWNS zidachotsedwa patatha mphindi 45 kuti ziwunikire momwe EWNS imakhudzira.
Kuyesera kulikonse kunachitika katatu. Kusanthula deta kunachitika motsatira ndondomeko yomwe yafotokozedwa mu Supplementary Data.
Zitsanzo za mabakiteriya a E. coli, Enterobacter, ndi L. innocua zomwe zapezeka ku EWNS (mphindi 45, kuchuluka kwa EWNS aerosol 40,000 #/cm3) ndi zosawonekera zinapakidwa kuti ziwone momwe zimagwirira ntchito. Mpweya wotuluka unakhazikika kwa maola awiri kutentha kwa chipinda mu yankho la sodium cacodylate la 0.1 M (pH 7.4) ndi fixative ya 2.5% glutaraldehyde, 1.25% paraformaldehyde ndi 0.03% picric acid. Pambuyo potsuka, zinakhazikika ndi 1% osmium tetroxide (OsO4)/1.5% potassium ferrocyanide (KFeCN6) kwa maola awiri, zinatsukidwa katatu ndi madzi ndikuyikidwa mu 1% uranyl acetate kwa ola limodzi, kenako zinatsukidwa kawiri ndi madzi. Kutaya madzi m'thupi pambuyo pake kwa mphindi 10 iliyonse ya 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 wouma unadulidwa ndi kujambulidwa ndi TEM pogwiritsa ntchito JEOL 1200EX (JEOL, Tokyo, Japan), microscope yamagetsi yotumizira yomwe ili ndi kamera ya AMT 2k CCD (Advanced Microscopy Techniques, Corp., Woburn, MA, USA).
Kuyesera konse kunachitika katatu. Pa nthawi iliyonse, kutsuka kwa bakiteriya kunayikidwa katatu, zomwe zinapangitsa kuti pakhale mfundo zisanu ndi zinayi za deta pa mfundo iliyonse, ndipo avareji yake imagwiritsidwa ntchito ngati kuchuluka kwa bakiteriya pa chamoyo chimenecho. 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 kufotokoza kuwonongeka kwachilengedwe kwa mabakiteriya mkati mwa mphindi 45, Log-Reduction idawerengedwanso poyerekeza ndi kuwongolera pa mphindi 45 motere:
Pamene 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 idasankhidwa kuti iphunzire mokwanira kuwonetsa makhalidwe okhazikika komanso obwerezabwereza (Taylor cone, kupanga EWNS, ndi kukhazikika pakapita nthawi). Pa chithunzi 3 chikuwonetsa zotsatira za charge, kukula ndi zomwe zili mu ROS pamilandu iwiri. Zotsatira zake zafotokozedwanso mwachidule mu Table 1. Kuti muwone, Chithunzi 3 ndi Table 1 zikuphatikiza makhalidwe a EWNS8, 9, 10, 11 yomwe idapangidwa kale (baseline-EWNS). Mawerengedwe ofunikira a ziwerengero pogwiritsa ntchito mayeso a t-tailed awiri asindikizidwanso mu Supplementary Table S2. Kuphatikiza apo, deta yowonjezera ikuphatikiza maphunziro okhudza zotsatira za counter electrode sampling hole diameter (D) ndi mtunda pakati pa ground electrode ndi nsonga ya singano (L) (Zithunzi Zowonjezera S2 ndi S3).
(a–c) Kugawa kwa kukula kwa AFM. (d–f) Kakhalidwe ka mphamvu ya pamwamba. (g) Kufotokozera ROS ndi ESR.
Ndikofunikanso kudziwa kuti pazochitika zonse zomwe zili pamwambapa, ma ionization currents omwe adayesedwa anali pakati pa 2-6 µA, ndipo ma voltages anali pakati pa -3.8 mpaka -6.5 kV, zomwe zidapangitsa kuti mphamvu ya single-terminal EWNS iyi ikhale yosakwana 50 mW. . generation module. Ngakhale kuti EWNS idapangidwa pansi pa kuthamanga kwambiri, 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. Minda malinga ndi zochitika [-6.5 kV, 4.0 cm] ndi [-3.8 kV, 0.5 cm] imawerengedwa ngati 2 × 105 V/m ndi 4.7 × 105 V/m, motsatana. Izi ziyenera kuyembekezeredwa, popeza chiŵerengero cha magetsi ndi mtunda ndi chachikulu kwambiri pankhaniyi yachiwiri.
Pa chithunzi 3a, b chikuwonetsa kukula kwa EWNS komwe kumayesedwa ndi AFM8. Ma diameter apakati a EWNS a [-6.5 kV, 4.0 cm] ndi [-3.8 kV, 0.5 cm] adawerengedwa ngati 27 nm ndi 19 nm, motsatana. Kupatuka kwa geometric standard kwa magawidwe a ma cases [-6.5 kV, 4.0 cm] ndi [-3.8 kV, 0.5 cm] ndi 1.41 ndi 1.45, motsatana, kusonyeza kugawa kocheperako kwa kukula. Kukula kwapakati ndi kupotoka kwa geometric standard kuli pafupi kwambiri ndi baseline-EWNS, kukhala 25 nm ndi 1.41, motsatana. Pa chithunzi 3c chikuwonetsa kugawa kwa kukula kwa baseline EWNS komwe kumayesedwa pogwiritsa ntchito njira yomweyo pansi pa mikhalidwe yomweyi.
Pa chithunzi cha 3d, e chikuwonetsa zotsatira za kuwerengera 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. Poyerekeza ndi Baseline-EWNS (10 ± 2 e-), mphamvu yawo ya pamwamba ndi yayikulu kwambiri, kawiri kuposa [-6.5 kV, 4.0 cm] ndipo kanayi kuposa [-3 .8 kV, 0.5 cm]. 3f ikuwonetsa deta yoyambira yolipira ya EWNS.
Kuchokera pamapu a kuchuluka kwa ma EWNS (Zithunzi Zowonjezera S5 ndi S6), zitha kuwoneka kuti malo [-6.5 kV, 4.0 cm] ali ndi tinthu tambirimbiri kuposa malo [-3.8 kV, 0.5 cm]. Tiyeneranso kudziwa kuti kuchuluka kwa ma EWNS kunayang'aniridwa kwa maola 4 (Zithunzi Zowonjezera S5 ndi S6), pomwe kukhazikika kwa mibadwo ya EWNS kunawonetsa milingo yofanana ya kuchuluka kwa ma tinthu m'zochitika zonse ziwiri.
Chithunzi 3g chikuwonetsa EPR spectrum pambuyo pochotsa EWNS yowongolera (kumbuyo) pa [-6.5 kV, 4.0 cm]. ROS spectrum imayerekezeredwanso ndi EWNS baseline mu pepala lomwe linasindikizidwa kale. Chiwerengero chowerengedwa cha EWNS chomwe chikugwirizana ndi spin trap ndi 7.5 × 104 EWNS/s, chomwe chikufanana ndi Baseline-EWNS8 yomwe idasindikizidwa kale. EPR spectra idawonetsa momveka bwino kukhalapo kwa mitundu iwiri ya ROS, komwe O2- inali yochulukirapo, pomwe OH• inalipo pang'ono. Kuphatikiza apo, kufananiza mwachindunji kwa mphamvu yayikulu kunawonetsa kuti EWNS yowongolera inali ndi ROS yochulukirapo 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 ya EUNS, kuyika kunali pafupifupi 100% ngakhale pa voltage yotsika ya 3.0 kV. Kawirikawiri, 3.0 kV ndi yokwanira kukwaniritsa kuyika 100% mosasamala kanthu za kusintha kwa mphamvu ya pamwamba. Pansi pa mikhalidwe yomweyi, mphamvu ya kuyika kwa Baseline-EWNS inali 56% yokha chifukwa cha kuyika kotsika (avereji ya ma elekitironi 10 pa EWNS iliyonse).
Chithunzi 5 ndi Gome 2 zikufotokoza mwachidule kuchuluka kwa kuletsa kugwira ntchito kwa tizilombo toyambitsa matenda tomwe timayikidwa pamwamba pa phwetekere titayikidwa pa EWNS pafupifupi 40,000 #/cm3 kwa mphindi 45 pansi pa malo abwino kwambiri [-6.5 kV, 4.0 cm]. E. coli ndi L. innocua zomwe zimayikidwa zikuwonetsa kuchepa kwakukulu kwa matabwa 3.8 pambuyo pa mphindi 45 zoyikidwa. Pansi pa mikhalidwe yomweyi, S. enterica inawonetsa kuchepa kochepa kwa matabwa 2.2, pomwe S. cerevisiae ndi M. parafortuitum zinawonetsa kuchepa kwa matabwa 1.0.
Ma micrograph a ma electron (Chithunzi 6) omwe akuwonetsa kusintha kwa thupi komwe kumachitika chifukwa cha EWNS mu maselo a E. coli, Salmonella enterica, ndi L. innocua zomwe zimapangitsa kuti maselo asamagwire ntchito. Mabakiteriya oletsa adawonetsa ma nembanemba a maselo omwe anali osagwira ntchito, pomwe mabakiteriya omwe adawonekera adawononga nembanemba zakunja.
Kujambula zithunzi za ma elekitironi ndi mabakiteriya owonekera kunawonetsa kuwonongeka kwa nembanemba.
Deta yokhudza makhalidwe a physicochemical a EWNS optimized pamodzi ikuwonetsa kuti makhalidwe a EWNS (surface charge ndi ROS content) adakula kwambiri poyerekeza ndi deta yoyambira ya EWNS yomwe idasindikizidwa kale8,9,10,11. Kumbali ina, kukula kwawo kunakhalabe mu nanometer range, zomwe zikufanana kwambiri ndi zotsatira zomwe zidasindikizidwa kale, zomwe zimawalola kukhala mlengalenga kwa nthawi yayitali. Kuchulukana komwe kuwonedwa kumatha kufotokozedwa ndi kusintha kwa mphamvu ya pamwamba, komwe kumatsimikiza kukula kwa zotsatira za Rayleigh, kusakhazikika, ndi kuphatikizana komwe kungatheke kwa EWNS. Komabe, monga momwe Nielsen et al.22 adafotokozera, mphamvu yayikulu ya pamwamba imachepetsa kuuluka mwa kuwonjezera mphamvu/kupsinjika kwa madzi pamwamba. Chiphunzitsochi chidatsimikiziridwa mwa kuyesa kwa ma microdroplets22 ndi EWNS m'buku lathu lapitalo8. Kutayika kwa nthawi 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 mphamvu si yofanana ndipo ikutsatira 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.