Researcher:
Muti, Abdullah

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PhD Student

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Abdullah

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Muti

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Muti, Abdullah

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2017 - 201992020 - 202210

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    Investigation of the factors affecting the photothermal therapy potential of small iron oxide nanoparticles over the 730-840 nm spectral region
    (Royal Soc Chemistry, 2018) N/A; N/A; N/A; Department of Physics; Department of Chemistry; Bilici, Kübra; Muti, Abdullah; Duman, Fatma Demir; Sennaroğlu, Alphan; Acar, Havva Funda Yağcı; PhD Student; PhD Student; PhD Student; Faculty Member; Faculty Member; Department of Physics; Department of Chemistry; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; N/A; N/A; 23851; 178902
    The use of superparamagnetic iron oxide nanoparticles (SPIONs) as a sensitizer in photothermal therapy (PTT) is relatively new and the origin of such a phenomenon is not known. Usually, large crystals and aggregated particles are preferred in the literature, suggesting that these increase the absorbance of particles at the irradiation wavelength, and hence, provide a larger temperature increase. This study has two major goals: identification of the key factors that affect the photo-induced temperature increase in well-controlled experiments and the influence of laser irradiation on nanoparticle properties. Small, biocompatible poly(acrylic acid) coated SPIONs (PAA/SPIONs) were used since they are more practical for future medical use than large aggregates. We studied the impact of three major laser-dependent variables, namely the wavelength (between 728 and 838 nm), intensity (1.85-9.76 W cm(-2)) and power (105-800 mW) as well as attenuation at the irradiation wavelength, on photothermal heating achieved with PAA/SPIONs. Within the studied range of these variables, only the laser power plays a critical role on the magnitude of photothermal heating in solutions. There is no strong correlation between the attenuation at the excitation wavelength and the temperature increase. In addition, extensive characterization of SPIONs before and after irradiation revealed no significant difference, which supports the re-usability of SPIONs. Lastly, the PTT potential of these small PAA/SPIONs was demonstrated in vitro on HeLa cells. At these low laser powers no temperature increase in SPION-free water or cell death in SPION-free cells was detected. Hence, this study provides a new insight into the photothermal effect of SPIONs, provides a clear and repeatable experimental procedure and demonstrates great potential for small SPIONs to be exploited in PTT.
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    Sub-100-fs pulse generation from a Kerr-lens mode-locked Alexandrite laser
    (Optica Publishing Group (formerly OSA), 2018) Demirbaş Ümit; N/A; N/A; N/A; Department of Physics; Cihan, Can; Muti, Abdullah; Toker, Işınsu Baylam; Sennaroğlu, Alphan; PhD Student; PhD Student; PhD Student; Faculty Member; Department of Physics; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; N/A; 23851
    We report, to the best of our knowledge, the shortest pulses obtained from a Kerr-lens mode-locked multipass-cavity Alexandrite laser operating near 750 nm. The resonator produced 70-fs pulses with a time-bandwidth product of 0.331.
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    Continuous-wave mid-infrared laser operation of tm3+:ky3f10 at 2.3 mu m
    (Optical Society of America (OSA), 2019) Tonelli, Mauro; Petrov, Valentin; N/A; Department of Physics; Muti, Abdullah; Sennaroğlu, Alphan; PhD Student; Faculty Member; Department of Physics; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; College of Sciences; N/A; 23851
    We report continuous-wave lasing demonstration of a Tm-3(+):KY3F10 crystalline gain medium at 2343 nm. A narrow-linewidth, tunable, continuous-wave Ti3+ :sapphire laser was used to end pump a Tm3+:KY3F10 crystal with thulium doping of 8 at. %. With 1 W of pump power, the resonator with a 1% output coupler generated output powers of 31 and 122 mW in single-pumping and double-pumping configurations, respectively. Excitation efficiency of the laser was investigated for pump wavelengths in the 765-806 nm range. Four pump bands were identified in this wavelength range, with the two most efficient pump bands centered at 773 and 778 nm. The output of the laser could be tuned smoothly and continuously over a spectral width of 125 nm from 2260 to 2385 nm. The lifetime of the H-3(4) level was further measured to be 16 mu s, and the emission cross section was determined based on lasing threshold measurements.
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    Continuous-wave and graphene mode-locked operation of a Tm3+:KY3F10 laser at 2.3 μm
    (Optica Publishing Group (formerly OSA), 2019) Tonelli, Mauro; Bae, Ji Eun; Rotermund, Fabian; Petrov, Valentin; Department of Physics; N/A; Sennaroğlu, Alphan; Muti, Abdullah; Faculty Member; PhD Student; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; 23851; N/A
    We report, for the first time to our knowledge, continuous-wave, broadly tunable laser operation of the Tm3+:KY3F10 gain medium between 2260 and 2385 nm and graphene mode locking, yielding 976-fs pulses near 2340 nm.
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    Ag2S-Glutathione quantum dots for NIR image guided photothermal therapy
    (Royal Soc Chemistry, 2020) N/A; N/A; N/A; N/A; Department of Physics; Department of Chemistry; Hashemkhani, Mahshid; Bilici, Kübra; Muti, Abdullah; Sennaroğlu, Alphan; Acar, Havva Funda Yağcı; PhD Student; PhD Student; PhD Student; Faculty Member; Faculty Member; Department of Physics; Department of Chemistry; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; N/A; N/A; 23851; 178902
    Aqueous synthesis of glutathione (GSH) coated Ag2S quantum dots (QD) with strong emission in the medical imaging window (700-900 nm) was performed from AgNO3. Variations in temperature, time, pH and sulfur source (Na2S and thioacetamide) were studied to tune the emission wavelength and intensity of the QDs. The optimum synthesis conditions to produce the smallest QDs (ca. 7 nm) with the highest quantum yield (70%) and excellent stability were determined as 50 degrees C and pH 10 where Na2S was used in 2 h reactions. The cytotoxicity was evaluated with MTT assay on the HT29 and MCF7 cancer cell lines and indicated no significant toxicity of the QDs up to 200 mu g mL(-1). The Photothermal Therapy (PTT) potential was first investigated using a 795 nm, continuous-wave fiber coupled diode laser using aqueous solutions of QDs and then on HT29 and MCF7 cells. QD (150 mu g mL(-1)) treated MCF7 cells almost quantitatively died after 10 min irradiation at 795 nm (700 mW, 1.82 W cm(-2)) and the viability of HT29 cells dropped to 40%. Most cell death was late apoptotic/necrotic. This study indicates that such a laser irradiation procedure and the QDs are safe, yet their combination provides dramatic cell death upon short laser treatment. PTT coupled with strong intracellular optical signal promotes Ag2S-GSH QDs as potential theranostic nanoparticles.
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    Tunable continuous-wave laser operation of Tm3+:BaY2F8 near 2.3 µm
    (2020) Tonelli, Mauro; N/A; N/A; Department of Physics; Muti, Abdullah; Toker, Işınsu Baylam; Sennaroğlu, Alphan; PhD Student; PhD Student; Faculty Member; Department of Physics; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 23851
    We report, for the first time to our knowledge, tunable continuous-wave laser action in the Tm3+:BaY2F8 (BYF) crystal near 2.3 mu m. In the experiments, a BYF crystal doped with 3 at. % thulium was end pumped with a narrow-linewidth, tunable Ti3+ :sapplkire laser with up to 920 mW of incident power. Lasing was achieved for the two pump polarizations of E//x and E//y. The best power performance was obtained in the case of E//x, double-end pumping, where 100 mW of output power was obtained at 2290 nm with 920 mW of pump power and 1% output coupler. The laser could be continuously tuned from 2233 to 2385 nm. Excitation spectra for E//x and Elly pumping were measured in the 760-810 nm range, and the optimum pumping wavelength was determined to be 779 nm for E//x. By using the lifetime and lasing threshold data, the stimulated emission cross section at 2290 nm was further determined to be (0.66 +/- 0.06) x 10(-24) m(2).
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    Multimodal image-guided folic acid targeted Ag-based quantum dots for the combination of selective methotrexate delivery and photothermal therapy
    (Elsevier Science Sa, 2020) N/A; N/A; N/A; Department of Physics; Department of Chemistry; Hashemkhani, Mahshid; Muti, Abdullah; Sennaroğlu, Alphan; Acar, Havva Funda Yağcı; PhD Student; PhD Student; Faculty Member; Faculty Member; Department of Physics; Department of Chemistry; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; N/A; 23851; 178902
    Multifunctional quantum dots (QDs) with photothermal therapy (PTT) potential loaded with an anticancer drug and labelled with a targeting agent can be highly effective nano-agents for tumour specific, image-guided PTT/ chemo combination therapy of cancer. Ag-chalcogenides are promising QDs with good biocompatibility. Ag2S QDs are popular theranostic agents for imaging in near-infrared with PTT potential. However, theranostic applications of AgInS2 QDs emitting in the visible region and its PTT potential need to be explored. Here, we first present a simple synthesis of small, glutathione (GSH) coated AgInS 2 QDs with peak emission at 634 nm, 21% quantum yield, and excellent long-term stability without an inorganic shell. Ag2S-GSH QDs emitting in the nearinfrared region (peak emission = 822 nm) were also produced. Both QDs were tagged with folic acid (FA) and conjugated with methotrexate (MTX). About 3-fold higher internalization of FA-tagged QDs by folate-receptor (FR) overexpressing HeLa cells than HT29 and A549 cells was observed. Delivery of MTX by QD-FA-MTX reduced the IC50 of the drug from 10 mu g/mL to 2.5-5 mu g/mL. MTX release was triggered at acidic pH, which was further enhanced with local temperature increase created by laser irradiation. Irradiation of AgInS2-GSH QDs at 640 nm (300 mW) for 10 min, caused about 10 degrees C temperature increase but did not cause any thermal ablation of cells. On the other hand, Ag2S-GSH-FA based PTT effectively and selectively killed HeLa cells with 10 min 808 nm laser irradiation via mostly necrosis with an IC50 of 5 mu g Ag/mL. Under the same conditions, IC50 of MTX was reduced to 0.21 mu g/mL if Ag2S-GSH-FA.
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    Graphene mode-locked operation of Tm3+:YLiF4 and Tm3+:KY3F10 lasers near 2.3 µm
    (Optical Society of America (OSA), 2020) Tonelli, Mauro; Bae, Ji Eun; Rotermund, Fabian; Petrov, Valentin; N/A; N/A; Department of Physics; Canbaz, Ferda; Muti, Abdullah; Sennaroğlu, Alphan; PhD Student; PhD Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 23851
    We report experimental demonstration of graphene modelocked operation of Tm3+:YLiF4 (YLF) and Tm3+:KY3F10 (KYF) lasers near 2.3 mu m. To scale up the intracavity pulse energy, the cavity was extended, and double-end pumping was employed with a continuous-wave, tunable Ti3+:sapphire laser delivering up to 1 W near 780 nm. The extended Tm3+: KYF laser cavity was purged with dry nitrogen to eliminate pulsing instabilities due to atmospheric absorption lines, but this was not needed in the case of the Tm3+:YLF laser. Once initiated by graphene, stable uninterrupted mode-locked operation could be maintained with both lasers. With the extended cavity Tm3+:YLF laser, 921 fs pulses were generated at a repetition rate of 17.2 MHz at 2304 nm. 739 fs pulses were obtained at the repetition rate of 54 MHz from the Tm3+:KYF laser at 2340 nm. The corresponding pulse energy and peak power were 2.4 nJ and 2.6 kW for the Tm3+:YLF laser, and 1.2 nJ and 1.6 kW for the Tm3+:KYF laser. We foresee that it should be possible to generate shorter pulses at higher pump levels. (C) 2020 Optical Society of America
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    Continuous-wave and graphene mode-locked operation of a Tm3+:KY3F10 laser at 2.3 μm
    (Optica Publishing Group (formerly OSA), 2019) Tonelli, Mauro; Bae, Ji Eun; Rotermund, Fabian; Petrov, Valentin; N/A; Department of Physics; Muti, Abdullah; Sennaroğlu, Alphan; PhD Student; Faculty Member; Department of Physics; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; College of Sciences; N/A; 23851
    We report, for the first time to our knowledge, continuous-wave, broadly tunable laser operation of the Tm3+:KY3F10 gain medium between 2260 and 2385 nm and graphene mode locking, yielding 976-fs pulses near 2340 nm.
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    Dual laser activatable brominated hemicyanine as a highly efficient and photostable multimodal phototherapy agent
    (Elsevier Science Sa, 2021) Department of Chemistry; N/A; N/A; N/A; Department of Physics; Department of Chemistry; Department of Chemistry; Gündüz, Hande; Bilici, Kübra; Çetin, Sultan; Muti, Abdullah; Sennaroğlu, Alphan; Acar, Havva Funda Yağcı; Kölemen, Safacan; Researcher; PhD Student; PhD Student; PhD Student; Faculty Member; Faculty Member; Faculty Member; Department of Physics; Department of Chemistry; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Koç University Boron and Advanced Materials Application and Research Center (KUBAM) / Koç Üniversitesi Bor ve İleri Malzemeler Uygulama ve Araştırma Merkezi (KUBAM); Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; College of Sciences; 224496; N/A; N/A; N/A; 23851; 178902; 272051
    Dual phototherapy agents have attracted great interest in recent years as they offer enhanced cytotoxicity on cancer cells due to the synergistic effect of photodynamic and photothermal therapies (PDT/PTT). In this study, we demonstrate a brominated hemicyanine (HC-1), which is previously shown as mitochondria targeting PDT agent, can also serve as an effective photosensitizer for PTT for the first time under a single (640 nm or 808 nm) and dual laser (640 nm + 808 nm) irradiation. Generation of reactive oxygen species and photothermal conversion as a function of irradiation wavelength and power were studied. Both single wavelength irradiations caused significant phototoxicity in colon and cervical cancer cells after 5 min of irradiation. However, coirradiation provided near-complete elimination of cancer cells due to synergistic action. This work introduces an easily accessible small molecule-based synergistic phototherapy agent, which holds a great promise towards the realization of local, rapid and highly efficient treatment modalities against cancer.