Researcher:
Khan, Minahil

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PhD Student

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Minahil

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Khan

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Khan, Minahil

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2021 - 20245

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Researcher Of Publications: search.filters.isAuthorOfPublication.6ae4b656-a636-47a1-8e57-c6165d6cae1b

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Now showing 1 - 5 of 5
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    Selective antibacterial and antibiofilm activity of chlorinated hemicyanine against gram-positive bacteria
    (Elsevier B.V., 2024) Onbasli, Kubra; Department of Chemistry;Department of Physics;Department of Electrical and Electronics Engineering; Ataç, Nazlı; Gündüz, Hande; Koç, İrem; Khan, Minahil; Savani, Samira; Can, Füsun; Acar, Havva Funda Yağcı; Kölemen, Safacan; Koç University İşbank Center for Infectious Diseases (KU-IS CID); n2STAR-Koç University Nanofabrication and Nanocharacterization Center for Scientific and Technological Advanced Research; School of Medicine; College of Sciences; Graduate School of Sciences and Engineering; College of Engineering
    Antibiotic-free therapies are highly needed due to the limited success of conventional approaches especially against biofilm related infections. In this direction, antimicrobial phototherapy, either in the form of antimicrobial photothermal therapy (aPTT) or antimicrobial photodynamic therapy (aPDT), have appeared to be highly promising candidates in recent years. These are local and promising approaches for antibiotic resistant bacterial infections and biofilms. Organic small photosensitizers (PSs) are extensively preferred in antimicrobial phototherapy applications as they offer a great opportunity to combine therapeutic action (aPTT, aPDT or both) with fluorescence imaging on a single molecule. In this study, the bactericidal effect of cationic chlorinated hemicyanine (Cl-Hem)-based type I PS, which can function as a dual aPDT/aPTT agent, was investigated on both planktonic cells and biofilms of different gram-positive (E. faecalis and S. epidermidis) and gram-negative bacteria (P. aeruginosa and K. pneumoniae) with and without 640 nm laser irradiation. Cl-Hem was shown to induce a selective phototheranostic activity against gram-positive bacteria (E. faecalis and S. epidermidis). Cl-Hem exhibited both dose and laser irradiation time dependent bactericidal effect on planktonic and biofilms of S. epidermidis. These results clearly showed that highly potent Cl-Hem can treat resistant microbial infections, while allowing fluorescence detection at the same time. High biofilm reduction observed with combined aPDT/aPTT action of Cl-Hem together with its non-cytotoxic nature points out that Cl-Hem is a promising PS for antibacterial and antibiofilm treatments. © 2024 Elsevier B.V.
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    A leucine aminopeptidase activatable photosensitizer for cancer cell selective photodynamic therapy action
    (Elsevier Sci Ltd, 2021) N/A; N/A; N/A; Department of Chemistry; N/A; Department of Physics; Department of Chemistry; Department of Chemistry; Department of Physics; Department of Chemistry; Arslan, Büşra; Bilici, Kübra; Demirci, Gözde; Almammadov, Toghrul; Khan, Minahil; Sennaroğlu, Alphan; Acar, Havva Funda Yağcı; Kölemen, Safacan; Master Student; PhD Student; Master Student; Researcher; PhD Student; Faculty Member; Faculty Member; Faculty Member; 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); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; College of Sciences; N/A; N/A; N/A; N/A; N/A; 23851; 178902; 272051
    Activity based photosensitizers (PS) continue to attract great attention as they enable selective photodynamic therapy action on cancer cells while sparing normal cells even under light irradiation. Sensitivity to specific enzymes that are differentially overexpressed in cancer cells is crucial in the design of activatable PSs. In this direction, we report here, for the first time, a leucine aminopeptidase (LAP) activatable PDT agent (HCL), which is a red-shifted, water soluble and photostable brominated hemicyanine derivative. HCL was activated by endogenous LAP enzyme selectively in A549 (lung) and HCT116 (colon) cancer cells containing high LAP levels and induced effective photocytotoxicity with negligible dark toxicity. Furthermore, the fluorescence of the parent bromo-hemicyanine core was restored upon LAP-based activation in cancer cells. On the other side, no remarkable phototoxicity or fluorescence turn-on was detected in healthy L929 cells. Thus, HCL serves as an effective and tumour associated LAP-sensitive phototheranostic agent. We believe different cancer-associated analytes can be utilized in combination with near-IR absorbing scaffolds in the scope of activatable PDT designs to enrich the tumour-selective PS arsenal.
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    Tunable continuous-wave laser operation of Tm3+ ion doped tellurite glass near 2 μm
    (Elsevier, 2022) Denker, Boris; Galagan, Boris; Sverchkov, Sergei; Department of Physics; N/A; Department of Physics; Department of Physics; Morova, Yağız; Khan, Minahil; Sennaroğlu, Alphan; Researcher; PhD Student; Faculty Member; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 23851
    We provide an experimental investigation of the absorption saturation and 1.9-mu m lasing characteristics of a bulk Tm3+ :TZLN glass with the host composition of 74TeO(2)-12ZnO-4La(2)O(3)-10Na(2)O. By using a z-scan saturation measurement, the absorption cross section at 794 nm was determined to be 5 x 10(-21) cm(2) , in reasonable agreement with the value of 6 x 10(-21) cm(2) obtained from small-signal transmission measurement. In lasing experiments, double pumping was employed at 794 nm and the bulk Tm3+ :TZLN glass laser operated at the free running wavelength of 1926 nm. As high as 15.4 mW of continuous-wave output power was obtained with a 2.15% transmitting output coupler at the absorbed pump power of 284 mW. The slope efficiency with respect to the absorbed pump power was 7.1%. By using the threshold and power efficiency data, the stimulated emission cross section was further determined to be 6.8 x 10(-21) cm(2) at 1926 nm. Finally, continuous tuning of the laser output was demonstrated between 1845 and 1973 nm by using a quartz birefringent plate.
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    Development of a cysteine responsive chlorinated hemicyanine for image-guided dual phototherapy
    (Elsevier, 2022) Erkısa, Merve; Ulukaya, Engin; N/A; N/A; Department of Chemistry; N/A; N/A; N/A; Department of Physics; Department of Chemistry; Department of Chemistry; Department of Physics; Department of Chemistry; Savani, Samira; Onbaşlı, Kübra; Gündüz, Hande; Çelikbaş, Eda; Muti, Abdullah; Khan, Minahil; Sennaroğlu, Alphan; Acar, Havva Funda Yağcı; Kölemen, Safacan; Master Student; PhD Student; Researcher; PhD Student; PhD Student; PhD Student; Faculty Member; Faculty Member; Faculty Member; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Koç University AKKİM Boron-Based Materials & High-technology Chemicals Research & Application Center (KABAM) / Koç Üniversitesi AKKİM Bor Tabanlı Malzemeler ve İleri Teknoloji Kimyasallar Uygulama ve Araştırma Merkezi (KABAM); Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 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; N/A; 365341; 224496; N/A; N/A; N/A 23851; 178902; 272051
    A cysteine (Cys) activatable chlorinated hemicyanine (Cl-Cys) was introduced as a tumour selective image guided dual phototherapy agent. Cl-Cys exhibited a significant turn on response in its near-IR emission signal and activated its singlet oxygen generation as well as photothermal conversion potentials upon reacting with Cys. The laser irradiation of Cl-Cys induced significant cell death in cancer cells with high Cys level, while it stayed deactivated and non-emissive in a healthy cell line. A profound synergistic PDT/PTT effect was observed at high doses. Remarkably, Cl-Cys marks the first ever example of Cys-responsive small organic-based therapeutic agent and holds a great promise to develop new activity-based photosensitizers for dual phototherapy action.
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    Determination of the wavelength-dependent photothermal conversion efficiency of photosensitizers for photothermal therapy: application to Ag2S-glutathione quantum dots
    (Amer Chemical Soc, 2021) Department of Physics; N/A; N/A; Department of Chemistry; Department of Physics; Department of Chemistry; Sennaroğlu, Alphan; Khan, Minahil; Hashemkhani, Mahshid; Acar, Havva Funda Yağcı; Faculty Member; PhD Student; PhD Student; Faculty Member; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; 23851; N/A; N/A; 178902
    Nanoparticles have become popular photosensitizers for photothermal therapy (PTT), as they can be targeted to specific cancer tissues and deliver a chemotherapeutic drug, providing a multimodal therapeutic approach. Photothermal conversion efficiency of nanoparticles is critical in the assessment of their therapeutic use in PTT. We describe an accurate calorimetric method for the determination of the photothermal conversion efficiency of nanoparticles in solution. A tightly focused laser beam was used to irradiate a cuvette containing a solution of silver sulfide-glutathione quantum dots (Ag2S-GSH QDs), and the maximum steady-state temperature rise was measured with an infrared camera. The data were analyzed using two different photothermal conversion efficiencies, the intrinsic and external conversion efficiencies, to relate the induced heating power of the nanoparticles to the absorbed and incident optical powers, respectively. Measurements with a tunable Ti3+:sapphire laser showed that the intrinsic photothermal conversion efficiency of Ag(2)SGSH QDs exceeded 91% over the 720-810 nm wavelength range. The method was also used to analyze poly(acrylic acid)-coated superparamagnetic iron oxide nanoparticles (PAA/SPIONs), and the intrinsic photothermal conversion efficiency was determined to be 83.4% at 810 nm. This approach is useful for the evaluation of various potential nanoparticles for photothermal therapy applications.