| Abstract | Celuloza i njezini derivati, zbog velike površine i adsorpcijskih svojstava, pogodni su nosači različitih kozmetičkih i terapeutskih pripravaka te lijekova za kontroliranu isporuku. U ovom su radu istražena dva celulozna adsorbensa i adsorbati, cetilpiridinijev klorid kao antiseptik i amoksicilin kao lijek. Adsorpcija cetilpiridinijevoga klorida na celulozne supstrate praćena je pri 25 °C i različitim vrijednostima pH, pH 9, pH 6 i pH 4, elektrokinetičkom metodom potencijala strujanja i mikrogravimetrijskom metodom kvarcne mikrovage s praćenjem disipacije (QCM-D). Cetilpiridinijev klorid (CPC), kao adsorbat, primijenjen je u dvjema koncentracijama, 1 mmol/L i 2,4 mmol/L, za pamučnu tkaninu (PT) u realnom i celulozni film (MCF) u modelnom sustavu. Dodatno je CPC s amoksicilinom ugrađenim u njegove micele analiziran kao funkcionalni adsorbat za oba celulozna supstrata. Procesima adsorpcije u realnom i modelnom sustavu prethodila je analiza svih adsorbata i adsorbensa. CPC formulacijama (CPC1, CPC2,4 i CPC/Amox), kao adsorbatima, određeni su molarna koncentracija (c), vrijednost pH, vodljivost (), zeta potencijal čestica u otopini (ζ), hidrodinamički promjer (dH), površinska napetost (σ) i apsorpcijski spektri. Celulozni adsorbensi karakterizirani su kroz stupanj polimerizacije (DP), aktivnu površinu (BET), morfologiju (SEM), kemijski sastav (FTIR), zeta potencijal (ζ) i bubrivost. Odabrane metode primijenjene su s ciljem analize parametara koji utječu na adsorpciju CPC-a i CPC/Amoxa u realnom i modelnom sustavu kao i njihove desorpcije. Na temelju rezultata utvrđena je korelacija između metoda, potencijal strujanja i QCM–D-a, kao i korelacija realnog (PT) i modelnog (MCF) sustava. Rezultati istraživanja potvrdili su postavljene hipoteze da je ugradnjom amoksicilina u CPC micele moguće razviti novu funkcionalnu koloidnu formulaciju. Procesi adsorpcije pokazali su da je amoksicilin ugrađen u CPC micele prihvatljiv adsorbat za pamučnu tkaninu i celulozni film. Elektrokinetička metoda potencijal strujanja prihvatljiva je za istraživanje adsorpcije CPC micela i njegove koloidne formulacije CPC/Amox u sustavu s celuloznim supstratima. Mikrogravimetrijska metoda QCM-D također je prihvatljiva za istraživanje adsorpcije CPC micela i njegove koloidne formulacije CPC/Amoxa u sustavu s celuloznim filmom (MCF). Rezultati desorpcije CPC/Amoxa s pamučne tkanine dobiveni metodama potencijala strujanja i QCM–D-a pokazali su najbolju stabilnost adsorbirane količine pri pH 9. Rezultati statističke analize potvrdili su da je moguće uspostaviti korelaciju između metoda potencijala strujanja i QCM-D-a za istraživanje adsorpcije iz CPC formulacija na celulozne supstrate. |
| Abstract (english) | Cellulose and its derivatives are suitable as carriers for various cosmetic applications, therapeutic preparations and controlled drug delivery due to their large surface area and adsorption properties. They are characterized by their biocompatibility, hydrophilicity, biodegradability, non-toxicity and antimicrobial properties. In this resaerch, cotton fabric and cellulose film were investigated as a drug delivery systems. The adsorption of cetylpyridinium chloride on cotton cellulose and cellulose film was studied by varying the pH, concentration and functionalization of the micelles. Cetylpyridinium chloride (CPC) is the quaternary ammonium compound, which owns antibacterial properties due to its hydrophobic segment in the molecule. Interactions with gram-positive bacteria occur by interrupting the function of the membrane, leakage of cytoplasm and its destruction. Due to its antibacterial properties and its use in pharmacology and dentistry, the possibility of encapsulating amoxicillin in its micelles was investigated. Amoxicillin (Amox) is a broad spectrum antibiotic that belongs to the penicillin group, and is used in human and veterinary medicine. Due to its structure, the presence of acidic (carboxyl, -COOH) and basic (amino, -NH2) groups. Amox shows different ionic forms in aqueous solutions, depending on pH, which has been shown to be an advantage. The adsorption of cetylpyridinium chloride on the cellulose substrates was monitored at 25 °C and different pH values, pH 9, pH 6 and pH 4, using the electrokinetic method of streaming potential and the gravimetric method of the quartz-crystal microbalance with dissipation (QCM-D). Cetylpyridinium chloride was applied as an adsorbate at two cncentrations, 1 mmol/L and 2.4 mmol/L, for cotton fabric (PT) in the real, and cellulose thin films (MCF) in the model system. In addition, CPC with Amox embedded in its micelles was analyzed as a functional adsorbate for both cellulosic substrates. The adsorption processes in the real and model systems were preceded by the analysis of adsorbates and adsorbent properties. Cetylpyridinium chloride as adsorbate (CPC1, CPC2,4 and CPC/Amox) was characterized by the determination of molar concentration (c), pH, conductivity (), zeta potential of particles in solution (ζ), hydrodynamic diameter (dH), surface tension (σ) and absorption spectra. Cellulose adsorbents were characterized by degree of polymerization (DP), active surface area (BET), morphology (SEM), chemical composition (FTIR), zeta potential (ζ) and swelling. The selected methods were applied with the aim of analyzing the parameters affecting the adsorption of CPC and CPC/Amox in real and model systems as well as their desorption. Based on the results, the correlation between the methods, streaming potential and QCM-D, as well as the correlation of the real (PT) and model (MCF) systems, was determined. The research results confirmed the hypothesis that the incorporation of amoxicillin into CPC micelles allows the development of a new functional colloidal formulation. The adsorption processes showed that amoxicillin embedded in CPC micelles is an acceptable adsorbate for cotton fabric and cellulose film. Surface modification of textile materials, in this case cellulose substrates, for biomedical application is primarily aimed at introducing specific surface functionalities that change the surface charge of the material. The surface modification of the material can be detected by measuring the surface charge, for which the streaming potential method is suitable. The problem is that the measurements must be performed in the presence of an electrolyte, which can affect the properties of the adsorbate. In this research, it was previously determined that the electrolyte KCl at a concentration of 1 mmol/L has no effect on the physical and chemical properties of the adsorbate. According to the obtained results electrokinetic method the streaming potential is acceptable for studying the adsorption of CPC micelles and its colloidal formulation CPC/Amox in a system with cellulose substrates. The quartz crystal microbalance with dissipation was used to determine interfacial mass changes by dependence of QCM resonance frequency. The benefits of this method are shown by the fast adsorption data and a small amount of sample. In addition, it provides information about the change of mass on the tested sample, but also about changes on the surface, which differ by changes in dissipation. For this research, the results of QCM-D method proved to be convinient for the analysis of adsorption of CPC micelles and CPC/Amox on the model cellulose thin films (MCF), which provide information about surfaces during adsorption of colloidal formulations. The results of CPC/Amox desorption from cotton fabric obtained by the streaming potential method and QCM-D showed the best stability at pH 9. The results of the statistical analysis confirmed that it is possible to establish a correlation between the streaming potential method and QCM-D for the study of adsorption of CPC from colloidal formulation on cellulosic substrates. |
