Browsing by Author "Khan, Rehan"

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Open Access
“Clicked” Porphyrin-cucurbituril conjugate: a new multifunctional supramolecular assembly based on triglycosylated porphyrin and Monopropargyloxycucurbit[7]uril
(Wiley-VCH Verlag, 2018) Koç, Ahmet; Khan, Rehan; Tuncel, Dönüş
The design, synthesis, and characterization of a new multifunctional supramolecular assembly based on a photoactive glycosylated porphyrin and covalently attached monofunctionalized cucurbit[7]uril (CB7) are reported. To obtain the target supramolecular assembly, azido-functionalized tetraphenylporphyrin (TPP) was used as a building block. TPP was first glycosylated by copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, then a monopropargyloxy-functionalized-CB7 unit was conjugated to glycosylated TPP with a second CuAAC reaction. The host-guest chemistry of the assembly was investigated by 1H NMR experiments to establish the availability of the CB7 as a host. The imidazole-based guest, which is known to have high affinity toward CB7, was observed to form inclusion complex with CB7. It was also demonstrated that this supramolecular assembly can serve as an efficient photosensitizer for the generation of singlet oxygen.
Open Access
Cucurbituril containing supramolecular nanomaterials
(The Royal Society of Chemistry, 2019-01) Khan, Rehan; Tuncel, Dönüş
National Magnetic Resonance Research Center UMRAM Cucurbituril-based supramolecular nanomaterials are getting increasing attention due to their tailorable properties and functions. By making use of the host–guest chemistry of cucurbiturils, a variety of nanostructured materials, including nanoparticles, micelles, vesicles and capsules, have been prepared with many potential applications in such areas as theranostics, photonics, sensing and catalysis. The nanostructured materials prepared in this way are reversible but stable; that is an important feature in stimuli-responsive cargo delivery. Cucurbituril-based nanostructured materials could also be prepared by conjugating the mono- or multifunctionalized cucurbituril (CB) derivatives to suitable substituted platforms. With this method, it is also possible to prepare nanoparticles and capsules. Accordingly, this chapter will discuss the recent advances in cucurbituril-based supramolecular nanomaterials, and special emphasis will be given to supramolecular nanomaterials formed through the host–guest chemistry of cucurbiturils and functionalized CB-based nanoparticles, but capsule formation will not be discussed in this chapter as Kim et al. reviews this topic in Chapter 10.
Open Access
Engineering red-emitting multi-functional nanocapsules for magnetic tumour targeting and imaging
(Royal Society of Chemistry, 2020-03) Wang, J. T.-W.; Martino, U.; Khan, Rehan; Bazzar, Maasoomeh; Southern, P.; Tuncel, Dönüş; Al-Jamal, K. T.
In this work we describe the formulation and characterisation of red-emitting polymeric nanocapsules (NCs) incorporating superparamagnetic iron oxide nanoparticles (SPIONs) for magnetic tumour targeting. The self-fluorescent oligomers were synthesised and chemically conjugated to PLGA which was confirmed by NMR spectroscopy, FT-IR spectroscopy and mass spectrometry. Hydrophobic SPIONs were synthesised through thermal decomposition and their magnetic and heating properties were assessed by SQUID magnetometry and calorimetric measurements, respectively. Magnetic nanocapsules (m-NCs) were prepared by a single emulsification/solvent evaporation method. Their in vitro cytotoxicity was examined in CT26 colon cancer cells. The formulated fluorescent m-NCs showed good stability and biocompatibility both in vitro and in vivo in CT 26 colon cancer models. Following intravenous injection, accumulation of m-NCs in tumours was observed by optical imaging. A higher iron content in the tumours exposed to a magnetic field, compared to the contralateral tumours without magnetic exposure in the same animal, further confirmed the magnetic tumour targeting in vivo. The overall results show that the engineered red-emitting m-NCs have great potential as multifunctional nanocarriers for multi-model bioimaging and magnetic-targeted drug delivery.
Open Access
Photoactive catalytically self-threaded 2D polyrotaxane network for visible light activated antimicrobial phototherapy
(American Chemical Society, 2020-11) Khaligh, Aisan; Khan, Rehan; Akolpoğlu Başaran, Duygu Deniz; Özkan, Melis; Tuncel, Dönüs
Here, we adapt the catalytically self-threading polyrotaxane synthesis for the construction of two-dimensional polymeric thin films using a water−oil interfacial polymerization method. In this method, the polymerization and the rotaxane formation take place simultaneously at the interface because of the presence of catalytically active cucurbit[6]uril (CB6) that can facilitate 1,3-dipolar cycloaddition reaction between alkyne and azide to form polytriazoles. By varying the concentration of the monomers, reaction time, and the size of the reaction vessel, it is possible to control the thickness and the lateral dimensions of the film. The as-synthesized film is free-floating, transparent, and robust enough to be transferred to any substrates. It contains photoactive porphyrin units which are quite appealing as a photosensitizer because of their capability to produce reactive oxygen species in high yield upon visible light irradiation. By taking advantage of these aforementioned features, this film was employed as a broad-spectrum photo-antimicrobial agent whose activity was switched on by light excitation against both Gram-negative and Gram-positive bacterial strains and switched off in the dark.
Open Access
Water-dispersible glycosylated poly(2,5′-thienylene)porphyrin-based nanoparticles for antibacterial photodynamic therapy
(Royal Society of Chemistry, 2019) Khan, Rehan; Özkan, Melis; Khaligh, Aisan; Tuncel, Dönüş
Here we report the preparation of water-dispersible glycosylated poly(2,5′-thienylene)porphyrin based nanoparticles by a nanoprecipitation method and demonstrate the application of these nanoparticles in antibacterial photodynamic therapy. The diameter of the nanoparticles is in the range of 50–80 nm and the resulting nanoparticles are stable in water without precipitation at least for a month. They have high singlet oxygen efficiency and display light-triggered biocidal activity against both Gram negative bacteria (Escherichia coli, E. coli) and Gram positive bacteria (Bacillus subtilis, B. subtilis). Upon white light irradiation for 10 min with a flux of 22 mW cm−2 of the E. coli suspension incubated with NPs (18 μg mL−1), a killing efficiency of 99% is achieved, whereas in the dark the effect is recorded as only around 8%.