Yara örtüsü olarak hazırlanan pektin esaslı ilaç dağıtım sistemlerine metal organik kafes yapıların (MOF) katkısı
Contribution of metal organic frameworks (MOFS) on pectin-based drug delivery systems prepared as wound dressing
Yazar: GAMZE BAĞIMSIZ
Danışman: PROF. DR. FATMA SENİHA GÜNER
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Kimya Mühendisliği Ana Bilim Dalı / Kimya Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2019
Konu: Kimya Mühendisliği = Chemical Engineering

Özet:
Meyve suyu yan sanayinin atık ürünü olan pektin, insan vücudundaki hücreler arası matrisin ana bileşenlerine yapısal benzerliği bulunan anyonik ve doğal bir polisakkarittir. Toksik değildir, biyouyumludur ve düşük üretim maliyetine sahiptir. Ayrıca antioksidan, antitümör ve anti-enflamatuar özelliklerine sahiptir.
Koordinasyon polimerleri olarak bilinen metal organik kafes yapılar (MOF), yüksek ilaç yükleme kapasiteli ve biyouyumlu hibrit malzemelerdir. MOF içeren pektin filmlerin ilaç taşıyıcı sistem olarak kullanılmaları son yıllarda ilgi çeken bir araştırma konusudur.
Bu çalışmada, ilaç yüklü MOF içeren pektin filmler hazırlanmıştır. Metal organik kafes yapısı olarak MIL-101(Fe), ilaç taşıyıcı sistem olarak ve pektinin daha iyi mekanik özellik kazanmasını sağlamak için kullanılmıştır. Filmler farklı pH, farklı ilaç ve MIL-101(Fe) miktarlarında sentezlenmiştir. Filmler tek yöntemle sentezlendi.Diğeri karşılaştırma örneği olarak hazırlandı. Sistemimizde ilaç olarak lokal antezik bir ilaç olan prokain kullanılmıştır.
Sisteme ilaç yükleme ve ilaç salım çalışmalarında UV-Vis spektrofotometre kullanılmıştır. Sisteme MOF ve ilacın başarılı bir şekilde eklendiğini incelemek için Fourier dönüşümlü kızılötesi (FT-IR) spektroskopisi kullanılmıştır. Polimerlerin ısıl karakterizasyonu, diferansiyel taramalı kalorimetre (DSC) kullanılarak azot atmosferinde incelenmiş ve camsı geçiş sıcaklığı (Tg) ve erime sıcaklığı (Tm) belirlenmiştir. Taramalı elektron mikroskobu (SEM) kullanılarak kurutulmuş filmlerin morfolojisi incelenmiştir. Polimerlerin viskoelastik özelliklerinin belirlenmesi için reolojik analiz yapılmıştır. Filmlerin hidrofilik-hidrofobik karakterleri temas açı ölçer ile belirlenmiştir. Esneklik, birim alan başına ortalama kütle (g m-2), filmin kalınlığı (mm), sıvı taşıma kapasitesi, dehidrasyon hızı, dispersiyon özelliği ve çözelti pH'ına etkisi gibi çeşitli yara örtüsü özellikleri incelenmiştir.
Çalışma sonunda elde edilen verilere göre, ilaç yüklü MOF partikülleri pektin içerisine başarıyla dağıtıldığı sonucuna varılmıştır. Hidrojel filmlerin ani ilaç salımı yapmadığı ve kontrollü ilaç salımına uygun davrandığı belirlenmiştir. Sentezlenen filmler arasında pH 5.8'de 30mg ilaç yüklenmiş 30 mg MOF partikülü içeren filmlerin, en iyi ilaç salımı davranışı gösterdiği belirlenmiş, yara örtüsü olarak kullanım için gerekli olan mekanik özelliklere sahip olması nedeniyle ve hücre canlılığı üzerindeki olumlu etkileri göz önüne alındığında yara örtüsü olarak kullanabileceğine karar verilmiştir.

Abstract:
The wound dressing material supplies pain relief, exudate absorption, infection and protection against contamination of contaminants, non-toxic, gas permeability, moisture, optimum pH and temperature environment.
The natural polymers used as a drug carrier have many advantages, including good biocompatibility, non-toxicity and adjustable controlled drug release properties.Pectin is an important polysaccharide commonly worked on as a drug delivery matrix.
Pectin consists of three polysaccharide regions, Homogalacturonan (HGA), Ramnogalacturonan-I (RG-I) and Ramnogalacturonan-II (RG-II).HGA is a linear homopolymer of α-(1 → 4) bound D-galacturonic acid. Pectin is an eco-friendly raw material, mainly derived from by-products of the juice and cider industry.
According to the degree of esterification (DE), which is the percentage of the esterified carboxyl groups, the pectins are divided into two classes.High methoxyl (HM) pectins (with DE>50%) necessitate relatively high soluble solids concentration and low pH for gel formation. Low methoxy (LM) pectins (with DE<50%) form hard gels under the influence of calcium or polyvalent cations that crosslinking galacturonic acid chains. The interaction of carboxyl group of LM pectin structure with Ca2+ induces the formation of the "egg box" structure.
Non-toxicity and low production costs,due to the simple gelling mechanism, the ability to rapidly form viscous solutions and stable gels in contact with aqueous solutions have led to the demand for pectin in biomedical applications such as drug delivery, gene transport, tissue engineering, wound healing and wound dressing.For application of pectin hydrogels to drug delivery, it is preferred to use a low molecular weight pectin with a low degree of esterification in the structure of the desired pectin.
Metal-organic frameworks (MOFs), a fastly growing interdisciplinary area in the last 20 years, have arised as a wide variety of crystal materials associated with very high porosity and enormous internal surface areas, combined with metal cation and organic binder.These properties enabled MOFs to be commonly used in gas storage,catalysis, drug transport and adsorption.
The MIL family is important due to its attractive qualities such as large pores (25-34 A°), outstanding surface area (3100-5900 m2/g) and the ability to associate functional groups into the frame. MIL (Lavoisier Institute Materials) is the first MOF group whose family has been underresearched as a potential drug delivery system.
A less toxic analogue, biocompatible and much more favorable drug carrier MIL-101 (Fe) was synthesized by Taylor-Pashowet.The zeotype crystal structure of MIL-101(Fe) is consisted of trimer iron (III) octahedral clusters linked together by 1,4-benzenedicarboxylate anions.
The use of MOF-containing pectin films as a drug delivery system is a research topic. It is advantageous that the pectin films containing MOF can be used as dressings due to their biocompatibility and high mechanical properties.
In this study, pectin film with MOF were synthesized. The drug was loaded into the MOF particles and the pectin film containing the drug loaded MOF particles was prepared. MIL-101(Fe) is used as a controlled drug delivery system and to provide better mechanical properties of pectin film.
There are many factors known to be effective in wound healing and intracellular and extracellular pH is particularly significant.Schneider and colleagues showed that pH is an important additive factor in the healing process and different pH ranges are necessary for the healing stages.Studies have also informed that changes in pH may influence wound closure, graft uptake, microbial infection rates, bacterial virulence, and biofilm formation.
The regeneration of the natural acidic environment in the skin can help to efficiently decrease the microbial load on the body surface, even if they are very resistant to antibiotics. As the innate plea of the body, the wound pH value shifts to acidic medium. Chronic wound pH values range from 5.45 to 8.65 with an average pH of 7.42. Low pH and higher wound temperature are suitable for recovery.
pK values vary according to the DE of pectin; the pK value of pectin with a degree of % 65 esterification was 3.55, whereas the pK value of pectin with 0% esterification degree was 4.10. The pH 3.5, where approximately 50% chargeable groups are ionized, which are equal to the pectin pKa value (3.38-4.10), may be connected to the lower ionized carboxyl group. In fact, a higher charge density is informed when the pH of a solution is above the apparent pKa of the pectin. Furthermore, the binding of Ca2+ ions increases with pH, with a maximum level of pH 5-7.5. Because of this, the films were synthesized in different pH (5.8, 8.2, 9.1 and 9.8).
Procaine (2-(diethylamino) ethyl- 4-aminobenzoate) was used as a drug in this study. Procaine is an anesthetic agent specified for induction of local or regional anesthesia, especially for oral surgery. It was first suggested in 1909 that local anesthetic drugs had antibacterial properties and procaine was reported to inhibit 65.8% of the 1279 clinical bacteria isolates at concentrations up to 2.0%.pKa value of procaine is 8.05.
In order to understand the MOF drug carrying capacity, the films containing different amounts of drugs (30mg and 60mg) and MOF (30mg and 50mg) were synthesized. The synthesis was performed using matrix diffusion (comparison examples) and membrane diffusion methods.
Membrane diffusion systems; the drug is placed in a tank surrounded by a swelling or non-swelling polymeric layer. Membrane systems can be prepared in a variety of ways such as sheet, film, capsule, microcapsule. In matrix diffusion systems, the drug is dissolved or dispersed in the solid polymer. Fabrication of matrix systems is easier and cheaper than membrane systems.
Drug delivery and drug release analysis to the system were determined using UV-Vis spectrophotometer. Fourier transform infrared (FT-IR) spectroscopy was used to examine the successful addition of MOF and drug to the pectin film.
Crystal structures of MOF particles and synthesized films were investigated by X-ray diffraction (XRD) method. The thermal characterization of the polymers was investigated using differential scanning calorimetry (DSC).
Morphological examination of dried films using scanning electron microscopy (SEM) was performed. The rheological analysis was performed to determine the viscoelastic properties of the films. The contact angle analysis was performed to determine the hydrophilic-hydrophobic character of the films.
Modern dressings have many desirable features, including biodegradability, bioabsorbability and ease of administration, flexibility, comfort and bacterial resistance. The standard properties required for various dressings such as elasticity, average mass per unit area (g m-2) and thickness (mm) of hydrogel films, fluid handling capacities, dehydration rate, dispersion properties and pH shift capacity of wound dressings were tested. Hydrogel films are hydrophilic structures that allow water to penetrate and swell with water. Therefore, swelling rates of films were examined.
As a result of FTIR analysis, specific peaks of pectin, MOF and the procaine were observed in FTIR spectrum. In the SEM images the smooth structure of the pectin and the MOF particles scattered over the pectin surface were observed.
XRD patterns of MOF were found to be in accordance with the literature. The XRD patterns of the crystal structure of MOF were seen in the XRD pattern of pectin- MOF film. According to the SEM, XRD and FTIR results, drug-loaded MOF was successfully distributed to pectin film. As expected, hydrogels were swollen up to 100 times their weight and controlled drug release.
With the contact angle value of films increased after adding MOF, the hydrophilic pectin film has gained hydrophobic properties. As a result of the rheological analysis, all samples showed a typical gel-like behavior.
Burst drug release was observed in a high amount of drug loading. Controlled drug release was observed in relatively low drug release. Among the synthesized films, films containing 30 mg of MOF particle (30M30PC5.8), 30 mg drug loaded at pH 5.8, showed the best drug release.
As a result of in vitro dressing tests, 30 mg MOF containing films had the essential mechanical properties. It was appropriate for the wound dressing material.
As a result of in vitro tests for cytotoxicity and wound healing properties of selected hydrogels, no negative effect on wound healing and cell viability was observed. It was observed that it had a positive effect on the cells and increased the number of cells.
When all properties of MOF-containing pectin films are evaluated together, it can be said that 30M30PC5.8 coded sample with good drug release and swelling rates has the potential to be used as a wound dressing.
It is known that the preparation of MOF-pectin hydrogels and the controlled drug release performance is examined for the first time.