Title Chitosan-based microspheres as drug delivery systems Title (croatian) Mikrosfere na temelju kitozana kao sustavi za dostavu lijeka Author Andrea Lončarević Vrabec Mentor Anamarija Rogina (mentor)Mentor Gloria Gallego Ferrer Committee member Zvjezdana Findrik Blažević (predsjednik povjerenstva)Committee member Marica Ivanković (član povjerenstva)Committee member Inga Urlić (član povjerenstva)Granter University of Zagreb Defense date and country 2025-03-17, Croatia Scientific / art field, TECHNICAL SCIENCES Universal decimal classificationUDC ) 66 - Chemical technology. Chemical and related industries Abstract Osteosarcomas, the most common type of primary bone tumor affecting children, adolescents, and young people, usually occur in long bones and are treated with surgery, which is preceded by biopsy and chemotherapy. Chemotherapy is often continued after surgery. Since antitumor drugs are administered intravenously, very high concentrations are required to inhibit tumor cell growth, exposing the entire body to the effects of the drug. Additionally, conventional chemotherapeutic drugs often have drawbacks, including reduced solubility, nonselective distribution, and adverse effects after oral or intravenous administration, which limit their clinical use. To reduce these negative effects, chitosan (CHT)-based drug delivery systems for local delivery have been proposed. In this study, microspheres based on chitosan physically crosslinked with copper(II) ions (CHT-Cu complex) were successfully prepared by emulsion and electrohydrodynamic atomization (electrospraying) process. Additionally, composite microspheres with calcium phosphate (CaP) ceramics in varying amounts (0, 5, and 10 wt.% of CaPs) were prepared. The emulsion-prepared CHT-Cu/CaP0 microspheres (microspheres without the addition of CaP) were spherical (circularity factor ~1) with a smooth surface and an average size of 30.1 ± 9.1 μm. The size of the electrosprayed microspheres ranged from 50 to 110 μm, depending on the CaP content. FTIR spectroscopy and X-ray diffraction analysis indicated interactions between the CHT-Cu matrix and the precipitated CaP filler, likely in the form of hydroxyapatite. An in vitro Cu2+ release study performed under conditions simulating an in vivo-like physiological environment indicated a significantly higher metal release from the microspheres in a complete cell culture medium compared to phosphate buffer at pH 7.4. Doxorubicin (DOX), used as a model antitumor drug, was incorporated into the CHT-Cu/CaP microspheres utilizing the pH-sensitivity of the CHT matrix. Successful drug loading was confirmed by fluorescence microscopy. DOX release was shown to depend on the pH value and chemical composition of the incubation medium, as well as the chemical composition of the drug-loaded microcarrier, indicating the ability of the DOX-loaded microcarriers to locally release DOX in a pH-triggered manner. It can be assumed that modification of CHT-based microspheres by adding CaPs increased the DOX loading efficiency. Biological evaluation of the as-prepared and drug-loaded microcarriers indicated synergistic effect of the drug and Cu2+ ions, and material selectivity towards MG-63 tumor cells. The optimal DOX-loaded material concentration for inhibiting osteosarcoma cell growth without having a harmful effect on normal cells was 0.5 mg mL^–1. Overall, the physicochemical and biological characterization of the prepared CHT-Cu/CaP microspheres and DOX-loaded microcarriers indicated the successful preparation of smart drug delivery systems for bone tumor treatment.
Abstract (croatian) Osteosarkomi, najčešća vrsta primarnog tumora (dugih) kostiju koji se javlja kod djece, adolescenata i mladih ljudi, obično se liječe kirurškim zahvatom, kojem prethode biopsija i kemoterapija. Kemoterapija se često nastavlja i nakon operacije. Budući da se antitumorski lijekovi administriraju intravenozno, potrebne su vrlo visoke koncentracije za inhibiciju rasta tumorskih stanica, a čime se cijelo tijelo izlaže djelovanju lijeka. Nadalje, konvencionalni kemoterapijski lijekovi često imaju štetne učinke, kao što su smanjena topljivost i neselektivna distribucija, što ograničava njihovu kliničku primjenu. Kako bi se smanjili ovi negativni učinci, predloženi su sustavi za lokalnu dostavu lijeka koji se temelje na kitozanu (CHT). U ovom radu, mikrosfere na temelju kitozana fizikalno umreženoga s bakrovim(II) ionima (CHT-Cu kompleks) uspješno su dobivene postupkom iz emulzije i primjenom elektrohidrodinamičke atomizacije (EHDA proces, elektroštrcanje). Dodatno su pripremljene i kompozitne mikrosfere s kalcij-fosfatnom (CaP) keramikom u različitim masenim udjelima (0, 5 i 10 mas.%).
CHT-Cu/CaP0 mikrosfere (mikrosfere bez dodatka CaP) dobivene iz emulzije bile su sferične (faktor sferičnosti ~1) s glatkom površinom i prosječnom veličinom od 30,1 ± 9,1 μm. Prosječna veličina CHT-Cu/CaP mikrosfera dobivenih EHDA procesom bila je između
50 i 110 μm, ovisno o količini CaP punila. FTIR spektroskopija i XRD analiza ukazale su na prisutnost interakcija između CHT-Cu matrice i istaloženoga CaP punila, vjerojatno u obliku hidroksiapatita. Otpuštanje Cu2+ iona iz CHT-Cu/CaP0 mikrosfera istraženo je pri simuliranim fiziološkim uvjetima, te rezultati ukazuju na znatno veće otpuštanje metalnih iona u mediju za staničnu kulturu u odnosu na fosfatni pufer pH vrijednosti 7,4. Doksorubicin (DOX), korišten kao modelni antitumorski lijek, uklopljen je u CHT-Cu/CaP mikrosfere koristeći svojstvo
pH-osjetljivosti CHT matrice. Uspješno uklapanje lijeka u mikronosače potvrđeno je primjenom fluorescentne mikroskopije. Otpuštanje DOX-a iz mikronosača ovisi o pH-vrijednosti i sastavu medija za inkubaciju, te o kemijskom sastavu mikronosača, što ukazuje na to da su
DOX-mikronosači pH-osjetljivi. Također, može se pretpostaviti da je modifikacija CHT-Cu mikrosfera dodatkom CaP-a povećala učinkovitost uklapanja DOX-a. Biološka ispitivanja pripremljenih CHT-Cu/CaP mikrosfera i mikronosača s uklopljenim lijekom pokazala su sinergijski učinak lijeka i Cu2+ iona te selektivnost materijala prema tumorskim stanicama. Kao optimalna koncentracija materijala s DOX-om za inhibiciju rasta stanica osteosarkoma bez štetnog učinka na zdrave stanice pokazala se 0,5 mg mL^–1. Zaključno, fizikalno-kemijska i biološka karakterizacija pripremljenih CHT-Cu/CaP mikrosfera i mikronosača s uklopljenim DOX-om ukazala je na uspješnu pripremu pametnih sustava za isporuku lijekova za liječenje tumora kostiju.
Keywords
calcium phosphates
chitosan
copper
doxorubicin
drug delivery systems
microspheres
osteosarcomas
pH-sensitivity
selective materials
Keywords (croatian)
kalcijevi fosfati
kitozan
bakar
doksorubicin
sustavi za dostavu lijeka
mikrosfere
osteosarkomi
pH-osjetljivost
selektivni materijali
Language english URN:NBN urn:nbn:hr:149:194301 Promotion 2025 Project Number: UIP-2020-02-6201 Study programme Title: Chemical Engineering and Applied Chemistry - Doctoral course Type of resource Text Extent 135 str. ; 30 cm File origin Born digital Access conditions Embargoed access Terms of use Created on 2025-03-19 13:22:47
