Theses supervised by Doç. Dr. Dönüş Tuncel
15 theses · İhsan Doğramacı Bilkent University
Kükürbitüril tabanlı çok işlevli fotoaktif yapıların sentezi ve karakterizasyonu
Preparation of cucurbituril based functional materials and their use in various applications ranging from biomedicine to optoelectronics have been studied intensely over the last decade. Supramolecular assemblies, networks and nanostructures constructed through noncovalent interactions of cucurbiturils with -conjugated, photoactive compounds have also been investigated and potential applications in the areas of theranostics, imaging, sensing and catalysis have been shown. In these cucurbituril based architectures, however, cucurbituril is disabled to act as a molecular receptor since they do not involve the covalent conjugation of cucurbituril directly to chromophore. The main motivation of this study is to synthesize multifunctional assemblies and nanostructures in which cucurbituril is covalently attached to various conjugated compounds including porphyrin, conjugated oligomers and polymers. A new multifunctional porphyrin-cucurbituril conjugate based on a photoactive mannosylated porphyrin and monoporpargyloxycucurbit[7]uril was synthesized. Azido-functionalized tetraphenylporphyrin (TPP) was used as a building block. TPP was first mannosylated by copper-catalyzed azide-alkyne cycloaddition (CuAAC), then a monoporpargyloxycucurbit[7]uril was covalently attached to the mannosylated TPP with a second CuAAC reaction. Singlet oxygen generation efficiency of the supramolecular assembly was measured and found to be significantly higher than that of unfunctionalized TPP. 1H NMR experiments were performed using a suitable guest, bisimidazolium, to prove the availability of CB7 in the assembly as a host. Bisimidazolium guest was observed to form inclusion complex with CB7, which is a promising result for the potential use of this supramolecular assembly as a drug carrier in conjunction with photodynamic therapy. Conjugated oligomers and polymers were synthesized from suitably-functionalized monomers via Pd-catalyzed cross-coupling reactions and their characterizations were performed. Their assemblies and nanostructures with covalently attached functionalized cucurbiturils were investigated. Redox sensitive crosslinked conjugated oligomer nanoparticles (CONs) were synthesized from a conjugated oligomer, OFVBt-N3 and a disulfide bond-containing crosslinker via ultrasound-assisted copper-free click reaction in THF. These spherical and approximately 50 nm-sized CONs preserved their stability and size (≈60 nm) after dispersing them in water. The behavior of the CONs in the presence of glutathione (GSH) was studied in aqueous medium. It was observed that the CONs are rapidly disrupted by GSH, which is an effective S-S bond cleaving biomolecule that is overexpressed in cancer cells. These results imply that when nanoparticles are loaded with an anticancer drug, targeted delivery of the drug to cancer cells can be achieved by cooperative action of enhanced permeability and retention (EPR) effect and S-S bond cleavage by GSH.
Çeşitli nanotıp uygulamaları için kükürbitüril tabanlı supramoleküler yapılar
The supramolecular chemistry of cucurbiturils (CBs) has been rapidly advancing to span wide range of nanomedicine applications including but not limited to pharmaceutical drug formulation and delivery, bio/medical imaging and sensing, cancer therapy, tissue engineering, development of antibacterial/antiviral agents and protein modification. Owing to unique recognition properties and low cytotoxicity, the supramolecular assemblies of CBs are particular promises for biomedicine tasks. Inspired by these developments, three multifunctional supramolecular constructs of CBs containing photoactive conjugated compounds were prepared to be utilized in nanomedicine applications covering antimicrobial and anticancer photodynamic therapy (PDT), combined PDT and photothermal therapy (PTT) for the inactivation of bacteria, drug delivery and cellular imaging. A stable rotaxane, namely [5]-rotaxane, based on photoactive alkyne-substituted porphyrin and azide-substituted stopper group was synthesized through 1,3-dipolar cycloaddition reaction. Herein, cucurbit[6]uril (CB6) acts as both macrocycle and catalysis for the reaction and encapsulates formed triazole ring inside its cavity. [5]-rotaxane was further investigated and results revealed that it has ability to generate reactive oxygen species (ROS) including singlet oxygens in high yield even under quite low fluence of light and short exposure time and this, in turn, renders it ideal photosensitizer which remains stable at physiological pH (7.4) for prolonged times. By taking the advantages of aforementioned properties, [5]-rotaxane was employed as a broad-spectrum antibacterial agent against Gram-negative and Gram-positive bacteria as well as anticancer agent against human breast cancer cell line (MCF-7) via visible-light-induced generation of ROS. [5]-rotaxane possess negligible dark cytotoxicity upon complexation with CB6 and it can afford efficacious PDT of cancer and infectious diseases caused by bacteria. Another multifunctional photoactive supramolecular assembly was built through covalently binding of four cucurbit[7]uril (CB7) molecules, functioning as receptor, to a tetraphenyl porphyrin core using suitable linkers. In addition to its light-promoted antibacterial property, here, main objective was to combine chemo- and photodynamic cancer therapy which makes this study novel. Presence of CB7, enables host-guest interactions with anticancer drug, doxorubicin hydrochloride (DOX), and therefore this system was used to carry drug molecules achieving synergistic PDT and chemotherapy. Finally, CB7-capped hybrid nanoparticles (NPs) made up of red-emitting conjugated oligomer (COL) and gold nanoparticles (Au-NPs) were obtained through one-pot synthetic method. These hybrid NPs were found to own high photostability, thermal reversibility and high ROS generation capacity. Benefitting from these properties, combined photodynamic and photothermal killing efficiency of NPs towards Gram-positive and Gram-negative bacteria was verified. Additionally, cellular imaging capability of them was shown owing to their inherently fluorescent characteristics and this feature could be utilized for image-guided PDT applications.
Su ayrışmasından kaynaklanan elektrokatalitik hidrojen evrimi reaksiyonları için elektro-eğirilmiş heteroyapılı nanoliflerin tasarımı, sentezi ve uygulaması
Environmental problems and climate changes have increased the importance of studies on the development of sustainable and clean energy methods that can be an alternative to energy production technologies using fossil fuels in recent years. Green hydrogen is environmentally friendly and a high-capacity energy carrier, as it does not cause any toxic by-products during its production. For this reason, attempts are being made to increase the efficiency of green hydrogen produced from water splitting. Development of the catalytic activities and stability of electrocatalysts has gained great importance in order to increase the performance of the hydrogen evolution reaction (HER). This study examines the effect of Ni/NiO-reduced graphene oxide catalysts fabricated in the form of heterostructured fibers by electrospinning on their intrinsic and extrinsic activities and their performance for HER. In order to examine the stability, activity and kinetics of the synthesized electrocatalyst, studies such as linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), were carried out and Tafel curves were interpreted. It has been observed that the optimal electrocatalyst exhibits outstanding electrocatalytic performance with an over potential of -212 mV at 10 mA cm , and a Tafel slope of 90.6 mV dec in alkaline electrolyte. Morphological and structural characterizations of electrocatalysts were investigated using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy (TEM) methods. Key words: electrospinning, nanofibers, hydrogen evolution reaction, water splitting, heterostructure, reduced graphene oxide, nickel
Beyaz ışıma yapan konjuge polimer nanoparçacıkları: Çıtçıt tepkimeleriyle oluşturulan nanoyapıların ışımalarının förster rezonans enerji transferi ile ayarlanması
In this work, we present the design, synthesis and characterization of water-dispersible conjugated polymer nanoparticles with tunable emission wavelengths for their potential applications in the areas of white organic light emitting diodes and cellular imaging. Blue, green and red emitting polymers carrying azide or alkyne groups are utilized and assembled together through 1,3-dipolar cycloaddition (click reaction) to obtain stable, shape-persistent white-emitting nanoparticles. The emission properties can both be tuned by varying polymer concentration and nanostructure design as a result of intimate interactions between the polymers within the nanostructure, which facilitate a highly efficient Förster Resonance Energy Transfer (FRET). For this purpose, four different nanostructured architectures were designed and investigated. In the first method, NPs of donor and acceptor are prepared separately and then mixed physically at certain ratios. The second method involves the formation of homogenous solution of both donor and acceptor polymers in THF followed by formation of NPs from the resulting solution. And in the third and fourth methods, sequentially formed NPs were designed. In the former, donor NPs were core and coated with solution of the acceptor polymer as the outer shell, while the latter is quite the reverse where acceptor NPs form the core surrounded by the donor as the outer shell. Polymers used in this study are namely, poly[(9,9-bis{3-azidopropyl}fluorenyl-2,7-diyl)-co-benzene] (PFBN3) which is a blue emitter that serves as a donor, while poly[(9,9-bis(3-(prop-2 ynyloxy)propyl)fluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1,3}-thiadiazole)] (PFBT-Pgy) is a green emitting polymer whose absorbance strongly overlaps with the emission of the donor serves as the acceptor. Moreover, red emitting polymers such as poly[(2-azidoethyl)-2-(5-(thiophen-2-yl)thiophen-2-yl)thiophene (PTN3 ) and Poly[(4-(2-(prop-2-ynyloxy)ethyl)thiophen-2-yl)-co-(1.4-benzo{1,2,5}thiadiazole)] (PBTTH-Pgy) were incorporated into multi-shell nanoparticle design to form white emitting tandem nanoparticles. The morphology and photophysical properties were investigated by DLS, SEM, TEM and UV-VIS, Steady-State Fluorescence, Time-resolved Fluorescence Spectroscopy respectively.
Polimer ışık yayan diyotlar ve foto dinamik terapi uygulamara yönelik oligomerlerin, polimerlerin ve kükürbitüril tabanlı polirotaksanların sentezi
In the first part of this study, porphyrin-thiophene monomers, oligomers and polymer are synthesized for photodynamic therapy application. Water solubility and the ability of a photosensitizer to generate singlet oxygen for tumor destruction are important conditions for ideal photosensitizer in photodynamic therapy application. For this purpose, water soluble pendent groups are attached to the porphyrin monomers before coupling with thiophene monomer to form oligomers and polymer. The presence of sulfur atom in thiophene facilitates intersystem crossing due to spin-orbit coupling and thus will increase singlet oxygen generation. Consequently, the ability of singlet oxygen generation of the polymer is found to be higher than oligomers followed by monomers. In the second part of the thesis, the effects of cucurbit[n]uril on photophysical, electrochemical and thermal properties of ionic conjugated polymers in water are described. Conjugated polymers are well known for their interesting optical properties and are used in the area of light emitting diodes. However, their stacking nature reduces their fluorescent quantum yields and thus limits their further applications. If the interactions among the polymers chains are reduced or the polymer backbones are insulated in some means, the emission efficiency of the polymers could be enhanced. For this purpose, two different green emitting fluorene-thiophene based polymers (29 and 33) and their cucurbituril based polyrotaxanes counterparts (30 and 34) are synthesized through Suzuki Coupling. In both polyrotaxane 30 and 34, enhancement in optical properties was observed showing fluorescent quantum yields of 0.46 and 0.55 in water respectively comparing to polymers 29 and 33 which has only 0.10 and 0.35 in water respectively. Their optical and electroluminescent properties were further utilized by fabricating devices as multilayer white polymer light emitting diodes (PLEDs). The synthesized molecules are characterized by 1H-NMR, 13C-NMR, ESI mass spectrometry, UV-VIS, photoluminescence, time resolved fluorescence spectroscopy, FT-IR, elemental analysis gel permeation chromatography, size exclusion chromatography, thermogravimetric analysis and cyclic voltammetry.
Basit teranostik platformlar olarak uyaranlara hassas konjuge polimer nanoparçacıklar
In this study, green and near-infrared emitting stimuli responsive conjugated polymer nanoparticles that can be utilized simultaneously for chemotherapeutic drug delivery and bioimaging were synthesized. The nanoparticles are sensitive to low pH values of tumor microenvironment or elevated redox potential of some tumor types. These theranostic platforms could be used for in-vivo imaging and perform controlled-drug release triggered by an appropriate stimulus. For this purpose, green emitting polymer with fluorene and benzothiadiazole alternating units in the backbone and a conjugated polymer emitting in the red-NIR region based on thiophene and benzothiadiazole alternating units in the backbone were synthesized and characterized. Nanoparticles of these polymers (CPNs) were prepared by a simple method called nanoprecipitation where hydrophobic polymer chains collapse onto each other in aqueous media, trapping any other hydrophobic drug molecules (anticancer agent camptothecin in our case) in the environment inside the polymer matrix. Nanoprecipitation process was optimized for each polymer to obtain maximum drug encapsulation rate and a narrow nanoparticle size distribution under 100 nm. Resulting CPNs were stable for a long time in PBS buffer, water, bovine serum albumin and human plasma. SEM images showed spherical particles with a narrow diameter distribution. In vitro drug release studies, pH responsive CPNs showed faster drug release in more acidic media. Redox sensitive red polymer on the other hand showed a cleavage of disulfide bond in its structure in the presence of stimulus. To evaluate the cytotoxicity of drug loaded and blank CPNs RT-CES (real-time cell electronic sensing) assays with HuH-7 cell line have been carried out. While blank CPNs show an insignificant temporary cytotoxicity, camptothecin loaded nanoparticles match or outperform the growth inhibition effect of free camptothecin. Fluorescence microscopy images of HuH-7 cells incubated with CPNs clearly show CPNs that are internalized by cells. In conclusion, it was demonstrated that conjugated polymers could be used to fabricate theranostic platforms without the need for an additional imaging agent and their structures can be engineered to obtain stimuli responsive smart drug delivery systems. These results promise simple and easily fabricated smart systems that can selectively carry anticancer agents to tumors while enabling monitoring of drug distribution and inexpensive tumor imaging without using any harmful rays on the highly energetic side of the electromagnetic spectrum.
Spıon ve konjuge polimerlerin kullanımına dayanan suya karışabilen hibrit nanoparçacıkların iki yönlü görüntüleme uygulamları için sentezi ve karakterizasyonu
This study focuses on the synthesis and characterizations of conjugated polymer coated super-paramagnetic iron oxide nanoparticles for their potential uses in vivo and in vitro imaging. Water dispersible, stable super-paramagnetic iron oxide (SPIO) hybridized conjugated polymer nanoparticles are synthesized with three different types of conjugated polymers emitting in the region of blue, green and red. SPION, which is a T2 contrast agent due to its magnetic susceptibility, is taken into consideration because of its unique uptake mechanism by the Kupffer cells in the liver, spleen or bone marrow.[1] The core iron oxide nanoparticles are coated to increase blood circulation time, reduce the agglomeration of them and improve pharmacokinetic effect.2 Conjugated polymers utilized in this work were modified with allyl pendant groups in order to obtain cross linkable moieties. Polymer chains were crosslinked via [2+2] cycloaddition of ethylene units under UV light to confer stability .Cross-linking would not only confer stability to these hybrid nanoparticles but it can also help preventing the early leakage of SPIONs from the polymer matrix in the biological media. For this purpose, three polymers used in this study, which were poly[(9,9-bis{3- dihexyl}flourenyl-2,7-diyl)-co-(9,9-bis{3-diallyl}fluorenyl-2,7-diyl)] (PB), Poly[(9,9-bis ({3-diallyl}flourenyl-2,7-diyl)-co-(benzothiodiazole)] (PG) and iv poly[3-{(allyloxy)ethyl} (thiophene 2,5-diyl)-co-(5,5'-{2,2'}-bithiophene)] (P2). Nanoparticles of these polymers with and without SPIONs were synthesized. Optical and morphological characterizations were investigated via DLS, SEM, TEM, UV-Vis and Fluorescence spectroscopy.
Biyolojik uygulamalara yönelik monosakkarit fonksiyonlu konjuge polimer, polirotaksan ve oligomerlerin tasarım ve sentezi
In this work, the design, synthesis and characterization of fluorescent, water-soluble, multivalent glycoconjugates for their potential applications in active-targetted cellular theranostics through receptor-mediated endocytosis are presented. Gluco-functionalized thiophene monomers are utilized for the pre-functionalized Suzuki coupling polymerization of glycopolythiophenes and glycopolythiophenerotaxanes. The pre-functionalized glycopolythiophenerotaxane synthesis route was designed to provide in situ complexation between boronic ester thiophene monomer and water-soluble macrocycle cucurbit[7]uril, for the Suzuki coupling with the glycothiophene monomer in water. Red emitting oligomers carrying azide groups were utilized for the synthesis of post-functionalized glycoconjugate oligomers. These functionalizations were carried through 1,3-dipolar cycloaddition (click reaction) between azide groups and alkyne-functionalized monosaccharides (mannose or glucose). Structural and photophysical properties of glycopolythiophenes were investigated through ¹H-NMR, UV-VIS, and Fluorescence Spectroscopy. Monomers in synthetic steps were analysed through ¹H-NMR, IR, and ¹³C-NMR. Structural, photophysical and morphological properties of red oligomers were investigated through ¹H-NMR, HRMS-TOF, DLS, SEM.
Konjuge oligomerlerin ve nanoparçacıkların optoelektronik ve biyolojik uygulamları için sentezi ve karakterizasyonu
This project firstly aims to develop water dispersible conjugated nanoparticles by reprecipitation method for FRET based white light emission. Preliminary NPs study with only OFT Pgy and only OFVBt N3 were done in order to determine size and distribution of NPs. Overlapping optical properties of donor (OFT Pgy) and acceptor (OFVBt N3) give possibility to FRET applications. By click reaction in water, terminal sites of oligomers are connected and white emission is sealed by keeping D-A pair close. FRET based white light is widely used in optoelectronic applications such as OLEDs or more specifically WOLEDs. Since the white light covers all visible spectrum, different color emissions are obtainable depending on excitation wavelength. Various biosensor and bioimaging applications are also possible with white light emitting NPs, since they are readily and stably dispersed in water. In second part of the project, OFVBt N3 oligomer is cross-linked with di-sulfide containing crosslinker via copper catalyzed click reaction. NPs were synthesized in THF to obtain high click efficiency and redispersed in water, since the biological applications are targeted. OFVBt N3 oligomer is advantageous for bioimaging with its red emission close to IR region, since lower frequency emission overcomes the background auto-fluorescence and penetrates deeper in the body. Di-sulfide crosslinker, in addition to connecting the oligomer molecules and stabilizing NPs, provides possibility of drug delivery application. Since GSH (glutathione) or Trx (thioredoxin) like thiol bearing bio-molecules subsist in higher concentrations in tumorous tissues, di-sulfide bond can be cleaved, releasing the loaded drug from NPs. Thus, crosslinked OFVBt N3 NPs is a theranostic agent with an advantageous emission color for bio-imaging and a cleavable di-sulfide bond for drug delivery & controlled release. In last part of the study, white light emitting bi-oligomer nanoparticles were designed and obtained by using OFB Pgy and Porph N3. A quality white emission requires to cover all visible spectrum and overlapping optical properties of OFB Pgy (D) and Porph N3 (A) is used to white light emission by FRET. The purpose of clicking the oligomer pair is to stabilize the FRET efficiency. Moreover, using THF as the solvent is not only facilitated a better click chemistry, but also provided ease of applicability for solid state white light applications. Since THF evaporates easily, white light emitting NPs can form film on various surfaces. Thus, these NPs requires no host layer and can be applied directly to electrode surface when optoelectronic applications e.g. OLEDs or WOLEDs are considered. Keywords: Conjugated oligomers, conjugated oligomer nanoparticles, FRET, click reaction, white light emission.
Oligotiyofen-temelli makromoleküllerin öz-eşleşmesi yoluyla biyomedikal uygulamalara yönelik ışık yayan nanoyapıların inşası
This work discusses the synthesis and characterizations of oligothiophene-based macromolecules and the construction of nanostructures through self-assembly of these macromolecules in water. In order to prepare the macromolecules, first bi-functional oligothiophenes are synthesized, characterized and then, the properly functionalized polyethylene glycol is linked to oligothiophene through nucleophilic substitution reactions to obtain an amphiphilic macromolecule. Self-assembly of amphiphilic macromolecules in water are investigated; the size and the morphology of the resulting nanostructures are determined by various techniques including dynamic light scattering, SEM and TEM. Their optical properties are studied using UV-vis and fluorescent spectroscopies. Polyethylene oxide has been considered highly biocompatible and biodegradable material which make it candidate for the biological applications as carrier for bioactive materials and controlled releasing of the drugs.
Kükürbit[n]urillerin bir ditopik misafir molekül ve ışıyan bir konjüge polimer ile süpramoleküler kimyası
The general objective of this thesis is to explore the ability of cucurbit[n]uril (CB[n]) (n= 6,7,8) homologues to form nano-structured supramolecular assemblies with various organic guests through self-sorting, self-assembly and recognition.In the first part of the thesis, the selectivity and recognition properties of CB[n] homologues towards a ditopic guest have been investigated. The guest was synthesized through Cu(I)-catalyzed click reaction between the salts of N,N'-bis-(2-azido-ethyl)-dodecane-1,12-diamine and propargylamine and contain two chemically and geometrically distinct recognition sites, namely, a flexible and hydrophobic dodecyl spacer and a five-membered triazole ring terminated with ammonium ions.Complex formation between the guest and CB[6], CB[7] and CB[8] in the ratios of 1:2, 1:1 and 1:1, respectively, was confirmed by 1H NMR spectroscopy and mass spectrometry. It was also revealed that CB[n] homologues have ability to self-sort and recognise the guests according to their chemical nature, size and shape. Kinetic formation of a hetero[4]pseudorotaxane via sequence-specific self-sorting was confirmed and controlled by the order of the addition.In the second part, the effect of CB[n] homologues on the dissolution and the photophysical properties of non-ionic conjugated polymers in water were investigated. A fluorene-based polymer, namely, poly[9,9-bis{6(N,N dimethylamino)hexyl}fluorene-co-2,5-thienylene (PFT) was synthesized via Suzuki coupling and characterization was performed by spectroscopic techniques including 1D and 2D NMR(Nuclear Magnetic Resonans), UV?vis, fluorescent spectroscopy, and matrix-assisted laser desorption mass spectrometry (MALDI-MS)(Matrix Assisted Laser Desorption/Ionization Mass Spectroscopy ). The interaction of CB[6], CB[7] and CB[8] with PFT have been investigated and it was observed that only CB[8] among other CB homologues forms a water-soluble inclusion complex with PFT. Furthermore, upon complex formation a considerable enhancement in the fluorescent quantum yield of PFT in water was observed. The structure of resulting PFT@CB[8] complex was characterized through 1H-NMR and selective 1D-NOESY(The Nuclear Overhauser Enhancement Spectroscopy) and further investigated by imaging techniques (e.g. AFM(Atomic Force Microscopy), SEM(Scanning Electron Microscopy), TEM(Transmission Electron Microscopy) and fluorescent optical microscopy) to reveal the morphology. The results suggested that through CB[8]-assisted self-assembly of PFT polymer chains vesicle-like nanostructures formed. The sizes of nanostructures were also determined using dynamic light scattering (DLS(Dynamic Light Scattering)) measurements.
Suda dağılabilir polimer nanoparçacıklarının sentezi ve karakterizasyonu
In this study, novel water dispersible conjugated polymer nanoparticles having various potential applications in the areas including biomedicine and photonics have been synthesized from blue, green and yellow light emitting conjugated polymers. Their sizes, morphology, surface charges and optical properties have been determined using various techniques. Cell viability of nanoparticles was tested in mesenchymal stem cells.For the synthesis of nanoparticles, first the following polymers carrying a number of different functional groups and based on derivatives of fluorene and benzothiodiazole monomers are designed and synthesized using the Suzuki coupling reactions: Poly[(9,9-bis{propeny}fluorenyl-2,7-diyl)-co-(9,9-dihexyl-9H-fluorene)] (P1), poly[(9,9-bis{carboxymethylsulfonyl-propyl}fluorenyl-2,7-diyl)-co-(9,9-dihexyl-9H-fluorene) (P2), poly[(9,9- bis{propeny}fluorenyl-2,7-diyl))-co-(1,4-benzo-{2,1,3}-thiodiazole)] (P3), poly[(9,9- bis{carboxymethylsulfonyl-propyl}fluorenyl-2,7-diyl)-co(1,4-benzo-{2,1,3}-thiodiazole)] (P4), poly[(9,9-bis{3-bromopropyl}fluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1,3}-thiodiazole)] (P5), poly[(9,9-bis{3-azidopropyl}fluorenyl-2,7-diyl)-co-(benzothiadiazole)] (P6).Polymers were characterized by using spectroscopic techniques such as 1H-NMR, FT-IR, UV-Vis, Fluorescence spectrophotometer and Gel Permeation Chromatography (GPC).Conjugated polymers carry functional groups on their side chains, such as azide and allyl groups that can be cross-linkable using UV light to form shape-persistent, stable nanoparticles. Nanoparticles were characterized by various techniques before and after UV-treatment. Their sizes and morphologies were determined by using dynamic light scattering measurements (DLS) and imaging techniques such as scanning electron microscopy (SEM) and atomic force microscopy (AFM). For optical characterization UV-vis, fluorescent spectroscopies and FT-IR were used.CNPs affect on cells shows their nontoxic and biocompatible properties which give opportunity to use them in cell imaging.Keywords: Conjugated Polymers, water dispersible nanoparticles, cross-linking, cell imaging.
Suda dağilabilir çapraz bağli işiyan polimer nanoparçaciklarin sentezi ve karakterizasyonu
In this study, a novel synthetic method was demonstrated for the water-dispersible crosslinked light-emitting conjugated polymer nanoparticles with enhanced stability.In order to synthesize the novel conjugated polymer nanoparticles, thiophene-based monomers were synthesized with different functional groups such as bromine, hydroxyl and azide groups. These monomers were characterized by 1H-NMR spectroscopy.After the synthesis of the monomers, various polymers were synthesized via Suzuki coupling and oxidative polymerization. Their structural and optical properties were fully characterized by spectroscopic techniques such as 1H-NMR spectroscopy, FT-IR spectroscopy and Gel Permeation Chromatography (GPC).Finally, crosslinked conjugated polymer nanoparticles were synthesized by a diaminoalkyne crosslinker and various useful functional groups were introduced to the nanoparticles such as triazoles and amine groups. Incorporation of the hydrophilic functional groups to the conjugated polymer nanoparticles resulted with patchy, janus-like nanoparticles. CB6 was used as a catalyst for the first time in nanoparticle synthesis for 1,3-azide alkyne Huisgen cycloaddition which formed a conjugated polymer-based nanosized rotaxanes. Crosslinking of the conjugated polymer nanoparticles was also achieved by the irradiation of the nanoparticles under UV light in order to get shape-persistent nanoparticles.Various functional groups of the conjugated polymer nanoparticles make them highly versatile for biological studies such as cell imaging and drug delivery in biological systems. Synthesized nanoparticles were fully characterized by dynamic light scattering (DLS) measurement, transmission electron microscopy (TEM), FT-IR spectroscopy and UV-Vis spectroscopy.
Antikanser ilaç taşıyıcı ve hücre görüntüleme yapabilecek flüoresan konjuge polimer bazlı çok fonksiyonlu nanoparçacıklar
The main motivation of this study is to develop multifunctional nanoparticles which can perform simultaneously the drug delivery and cell imaging tasks. To this end, firstly nanoparticles (Nps) with an average diameter of about 25 nm and based on a green emitting, hydrophobic conjugated polymer, poly[(9,9-bis{propenyl}fluorenyl-2,7-diyl))-co-(1,4-benzo-{2,1,3}-thiodiazole)] (PPFBT) and Nps with an average diameter of about 150 nm and based on a red emitting, hydrophobic conjugated polymer, poly[(9,9-bis{3-azido-propyl}fluorenyl-2,7-divinylene)-co-(1,4-benzo-{2,1,3}-thiodiazole)] (PAPFVBT) were prepared, characterized and their convenience as a fluorescent probe for cell imaging was evaluated via in vitro cell assays.Then, drug loaded nanocapsules in which PPFBT or PAPFVBT acts both as a fluorescent reporter and the main matrix of the nanocapsules accommodating an anti-cancer drug, camptothecin (CPT), were synthesized through a facile, single step reprecipitation method. CPT is a hydrophobic, water-insoluble drug but the encapsulation improved its water-solubility. The CPT loading efficiency in the nanoparticles has been determined to be 100% when a drug to polymer ratio of 1:25 (w/w) was used. Cell viability of Human hepatocellular carcinoma cell line (Huh7) was investigated in the absence and presence of CPT using Sulforhodamine B (SRB) assay. SRB assay resultssupported further by the fluorescence microscope cell images clearly confirmed that blankand CPT-loaded PPFBT Nps have been taken up by the cells very efficiently and these nanoparticles were accumulated in the cytoplasm. Time and dose dependent SRB assay results indicate that the blank PPFBTNps are not toxic to the Huh7 cells up to 25 µM. However, even a very low dose of CPT was found to be sufficient to induce the apoptosis of the cells when it was delivered through nanoparticles. Thus, at the end of 48 h, the half maximal inhibitory concentration (IC50) of free CPT and CPT-loaded PPFBT Nps were calculated to be 0.9 µM and 0.1 µM respectively, corresponding to that CPT-loaded PPFBT Nps are 9 times more effective than free CPT. However, at the end of 72 h, the IC50 of free CPT and CPT-loaded PPFBT Nps decreased to 0.1 µM and 0.008 µM, respectively. In this case, CPT-loaded PPFBT Nps are 12.5 times more effective than free CPT in inducing the apoptosis of Huh7 cells. Although the free drug (CPT) reaches IC50 of 0.1 µM after 72 h, it is possible to achieve this value with CPT-loaded Nps at the end of 48 h.On the other hand, dose dependent SRB assay results indicate that the blank PAPFVBTNps are not toxic to the Huh7 cells up to 16 µM.At the end of 72 h, IC50of free CPT and CPT-loaded PAPFVBT Nps were calculated to be 0.03 µM and 0.1 µM respectively, corresponding to that CPT-loaded PAPFVBT Nps are 3.3 times less effective than free CPT. Having bigger size (~150 nm) of PAPFVBT Nps is the main reason of not being effective as PPFBT Nps (~25 nm).
Konjuge polimer nanoparçacıkların ilaç taşınımı ve biyolojik görüntüleme içeren biyomedikal uygulamaları
In this study, the ability of fluorene-based conjugated polymer nanoparticles in the delivery of anticancer therapeutics and bioimaging was investigated through in vitro cytotoxicity assessments and fluorescence imaging. In order to prepare the nanoparticles, green light emitting polymer,poly[(9,9-bis{6-dimethylaminohexyl}fluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1,3}-thiodiazole)] (PDAFBT),was synthesized via Suzuki coupling reaction and characterized by nuclear magnetic resonance (NMR), electrospray ionization mass spectroscopy (ESI-MS), matrix assisted laser desorption ionization mass spectroscopy (MALDI), fourier transform infrared spectroscopy (FT-IR), UV-visible absorption spectroscopy (UV-Vis) and fluorescence spectroscopies. PDAFBT nanoparticles were synthesized through reprecipitation method which is based on the injection of the polymer solution in a good solvent into a poor solvent for the polymer to enhance the collapse of polymer chains in the form of spherical nanoparticles. Anti-cancer drug, camptothecin (CPT), was entrapped into the PDAFBT nanoparticles via hydrophobic interaction during the nanoparticle formation. Size, surface charge, morphology and optical characterizations of blank and CPT loaded nanoparticles were investigated by dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis and fluorescence spectrocopies. In order to investigate the properties of nanoparticles as drug carrier, drug encapsulation efficiency (EE) and drug loading efficiency (LE) were determined and EE was found to be as 92% and 75% for the 1:35 and 1:25 polymer to drug ratios, respectively, while LE of PDAFBT nanoparticles was determined as 2.67±0.3 %. Preliminary drug release profile which needs to be strengthen statistically, of PDAFBT nanoparticles was analyzed and showed that almost 100% of the loaded CPT was released steadily during first 48h time period indicating that the release of CPT is not a burst process. Stability of blank and CPT loaded PDAFBT nanoparticles was examined in different biological media including cell culture medium, bovine serum albumine (BSA) andhuman serum. The precipitation in nanoparticle dispersion was observed due to adsorption of proteins onto the surface of polymers. In vitro dose dependent cytotoxicity of blank and CPT loaded PDAFBT nanoparticles was assessed through 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazoliumbromide (MTT) toxicology assay on human carcinoma breast cancer cell lines, namely,MDA-MB-231, MDA-MB-157 and MCF-7 cells. The blank PDAFBT nanoparticlesdo not exhibit significant toxicity to MDA-MB-231 and MDA-MB-157 cells up to 40 ?M, however, a linear decrease on the viability of MCF-7 cells was detected ata concentration higher than 2.5 ?M and nearly 40% of the cells were dead at 40 ?M.The half maximal inhibitory concentration (IC50 ) values of free CPT and CPT loaded PDAFBT NPs were calculated to be 4.50?M and 1.35?M for MDA-MB-157 cell line, respectively, and 1.97?M and 1.05?M for MDA-MB-231 cells, respectively. These results indicate clearly that the CT-loaded nanoparticles are more efficient than free CPT in destroying the cancer cells. Fluorescent microscope images show also the efficient internalization of blank and CPT-loaded nanoparticles by MDA-MB-157 and MDA-MB-213 cell lines. Preliminarily in vivo studies have been performed on embryonic zebra fish and C. Elegans animal models using these nanoparticles and the efficient uptake of nanoparticles by the tissues have been observed by fluorescent microscopy. This results indicate that CPNs are promising for imaging and delivery vehicles for time and dose dependent treatments.