Razvoj funkcionalnih obloga za rane s terapijskim (nano)sustavima kitozana i melatonina

doctoral thesis

• Title (english): Development of functional wound-dressings with chitosan and melatonin therapeutic (nano)systems
• Author: Marieta Duvnjak Romić
• Mentor: Anita Hafner (mentor)
• Committee member: Mario Jug (predsjednik povjerenstva)
• Committee member: Maja Šegvić Klarić (član povjerenstva)
• Committee member: Marjana Dürrigl (član povjerenstva)
• Granter: University of Zagreb; Faculty of Pharmacy and Biochemistry; (Department of pharmaceutical technology); Zagreb
• Defense date and country: 2019-10-23, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Pharmacy
• Universal decimal classification (UDC): 615 - Pharmacology. Therapeutics. Toxicology

Abstract

Cijeljenje rana dinamičan je dobro koordiniran biološki proces koji uključuje interakcije stanica, izvanstaničnog
matriksa i signalnih molekula. Proces cijeljenja obično se dijeli u četiri faze - hemostaza, upala, proliferacija i
maturacija i remodeliranje. Mnogi unutarnji i vanjski čimbenici, s infekcijom kao najčešćom, mogu poremetiti
kaskadu cijeljenja i potom dovesti do kroničnih stanja. Uz porast otporezistencije bakterija na amtibiotike, razvoj
inovativnih, funkcionalnih obloga za rane koje pružaju odgovarajuće uvjete vlage, zaštitu od vanjskih faktora te
omogućuju kontrolirano oslobađanje djelatne tvari u područje rane, jedan je od imperativa u istraživanju. U ovom je
radu tehnologijom sušenja raspršivanjem razvijena inovativna obloga za rane na bazi kitozana u obliku suhog praha i
karakterizirana i uspoređena s komplementarnim mikrosferama. Pripravljena su tri različita terapijska sustava:
kitozanske mikrosfere, kitozansko-poloksamerske mikrosfere te kitozansko-poloksamerske mikrosfere s uklopljenim
nanostrukturiranim lipidnim nosačima (NLC). Terapijski sustavi (obloge) su dizajnirani u obliku suhog praha koji
bubri u kontaktu s eksudatom rane, tvoreći in situ hidrogel. Obloge su potom okarakterizirane u pogledu fizikalnokemijskih
svojstava, in vitro oslobađanja lijeka, svojstava koja se odnose na vlagu, antibakterijske učinkovitosti, in
vitro biokompatibilnosti s staničnim linijama kože, in vitro potencijala za cijeljenje i dugoročne stabilnosti u suhom
stanju. Kitozansko-poloksamerske mikrosfere s uklopljenim NLC optimizirane su primjenom definitivnog pretražnog
dizajna. NLC obogaćene mikrosfere pokazale su poboljšana svojstva tečenja i produljeno oslobađanje lijeka pri
izlaganju blago kiselim uvjetima, kao i niži kapacitet bubrenja, prijenosa vodene pare i brzinu isparavanja. Pokazalo se
da su kitozansko-poloksamerske mikrosfere prikladne za primjenu kao obloga za rane koje stvaraju velike količine
eksudata, dok su mikrosfere obogaćene NLC pogodnije za primjenu za rane s umjerenim lučenjem eksudata. Ispitivani
sustavi pokazali su antimikrobnu aktivnost i potencijal inhibicije / iskorjenjivanja biofilma protiv sojeva S. aureus
ATCC i S. aureus MRSA. Kitozansko-poloksamerske mikrosfere s uklopljenim nanostrukturiranim lipidnim nosačima
pokazale su se kompatibilnima s dermalnim keratinocitima i fibroblastima in vitro, s respektabilnim potencijalom za
promicanje procesa zacjeljivanja rana. Mikrosfere u suhom stanju pokazale su dobru dugotrajnu stabilnost. Konačno,
predloženi in situ oblozi pokazali su komplementarni potencijal za poboljšanje cijeljenja različitih vrsta kroničnih
rana, održavanjem povoljnog vlažnog okruženja, istovremeno pružajući antibakterijsko utočište.

Abstract (english)

Wound healing is a dynamic well-coordinated biological process involving complex interactions among cells,
extracellular matrix components and signalling compounds, resulting in wound closure. Healing process is usually
divided into four overlapping phases – haemostasis, inflammation, proliferation and remodelling. Many internal and
external factors, with infection being the most common one, can disrupt the healing cascade and subsequently lead to
chronic and nonhealing states. Accompanied with growing bacterial resistance, design of functional wound dressings
that provide adequate conditions for healing in terms moist environment, gas exchange, protection from external
contamination and drug delivery, represents a great imperative and challenge. In this thesis, novel chitosan-based
wound dressing in the form of dry powder was developed by spray drying technology and evaluated and compared
with complementary microparticulate dressings. Three variants of melatonin loaded wound dressings were evaluated -
chitosan, chitosan/Pluronic® F127 and NLC enriched chitosan/Pluronic® F127 microspheres. Dressings were
designed in form of dry powder that swells in contact with wound exudate, forming an in situ hydrogel. Therefore,
dressings were characterized in terms of physico-chemical properties, in vitro drug release, moisture related properties,
antibacterial efficacy, in vitro biocompatibility with skin cell lines, in vitro healing potential and long-term stability in
dry state. Melatonin loaded NLC enriched chitosan/Pluronic® F127 microspheres was optimized employing definitive
screening design. NLC enriched microspheres showed improved flowability features and prolonged drug release when
exposed to slightly acidic conditions, as well as lower fluid uptake capacity, water vapour transition and evaporation
rate. Melatonin loaded chitosan/Pluronic® F127 microspheres were shown to be suitable for application as dressing
for wounds that produce high amounts of exudate, while NLC enriched microspheres were more appropriate for
application to moderately exuding wounds. Tested systems showed antimicrobial activity and biofilm
inhibition/eradication potential against S. aureus ATCC and S. aureus MRSA strains. Melatonin loaded NLC enriched
and NLC free chitosan/Pluronic® F127 microspheres were shown as biocompatible with dermal keratinocytes and
fibroblasts in vitro, with respectable potential to promote wound healing process. Powders in dry state demonstrated
good long-term stability. Conclusively, proposed in situ forming dressings showed the complementary potential to
improve healing of different types of chronic wounds by maintaining favourable moist environment, while providing
antibacterial shelter.

• Keywords: melatonin; kitozan; mikrosfere; sušenje raspršivanjem; nanostrukturirani lipidni nosači; cijeljenje rana
• Keywords (english): melatonin; chitosan; microspheres; spray drying; nanostructured lipid carriers; wound healing
• Language: croatian
• URN:NBN: urn:nbn:hr:163:242111
• Promotion: 2022
• Study programme: Title: Pharmacy and biochemistry; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor znanosti (doktor znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2022-11-08 14:30:43