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Publication Metadata only 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; 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; 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); 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; 272051Activity 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.Publication Metadata only A new magnetorheological damper for chatter stability of boring tools(Elsevier Science Sa, 2021) N/A; N/A; Department of Chemistry; Department of Mechanical Engineering; Saleh, Mostafa Khalil Abdou; Nejatpour, Mona; Acar, Havva Funda Yağcı; Lazoğlu, İsmail; PhD Student; PhD Student; Faculty Member; Faculty Member; Department of Chemistry; Department of Mechanical Engineering; Manufacturing and Automation Research Center (MARC); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Engineering; N/A; N/A; 178902; 179391Chatter is a limiting factor during boring of deep holes with long slender boring bars. In this article, a new magnetorheological (MR) damper is introduced to increase the stability of the boring process. The sponge-type configuration of the damper utilizes a minimal amount of MR fluid in the annulus around the boring bar. The MR fluid layer and the electromagnetic circuit are externally applied to the boring bar, which allows easy installation and adjustability in bar length. A custom made, bidisperse MR fluid is used to eliminate particle sedimentation and enhance the lifetime of the damper. The modal analysis of the boring bar with the new MR damper shows improvements in both the damping and the dynamic stiffness of the system. This enhancement significantly increases the chatter-free depth of cut on the stability lobe diagrams. This article presents the experimental validations on the boring of AL 7075 and Inconel 718 workpieces which are materials widely used in many aerospace applications. The damper is installed on a conventional boring bar for a CNC machining center setup, and its performance is tested under various machining conditions.Publication Metadata only A new substrate for glutathione reductase: glutathione coated Ag2S quantum dots(Elsevier, 2019) N/A; N/A; N/A; Department of Chemistry; N/A; Aydemir, Duygu; Hashemkhani, Mahshid; Durmuşoğlu, Emek Göksu; Acar, Havva Funda Yağcı; Ulusu, Nuriye Nuray; PhD Student; PhD Student; PhD Student; Faculty Member; Faculty Member; Department of Chemistry; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Health Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; School of Medicine; N/A, N/A; N/A; 178902; 6807Glutathione (GSH), a key player in various cellular processes including detoxification, anti-oxidant defense system and cell proliferation is also a potentially good coating material for luminescent quantum dots. GSH is oxidized to oxidized glutathione (GSSG) under oxidative stress and then reduced back by glutathione reductase (GR) enzyme to maintain the balance of GSH/GSSG ratio. In this frame, GSH stabilized quantum dots (QDs) have never been evaluated as GR substrate. Here, GSH coated Ag2S QDs, luminescent in the medical window, were prepared and their GR activity were tested. We have shown by spectrophotometric methods that GSH-Ag2S acted as a substrate-analog for GR enzyme that had lower activity compared to the original substrate GSSG. These results provide a new perspective in the evaluation of QDs in medical applications, enzyme activity or level detection as well as possible means to study enzymes.Publication Metadata only A novel magnetomechanical pump to actuate ferrofluids in minichannels(Begell House, Inc, 2011) Bilgin, Alp; Kurtoglu, Evrim; Erk, Hadi Cagdas; Sesen, Muhsincan; Kosar, Ali; Department of Chemistry; Acar, Havva Funda Yağcı; Faculty Member; Department of Chemistry; College of Sciences; 178902An improvement in the current methods of ferrofluid actuation was presented in this paper. A novel magnetomechanical microfluidic pump design was implemented with a ferrofluid as the active working fluid. Obtained flow rates were comparable to previous results in this research line. It was also seen that the basic pump architecture, which the subject pump is based on, enables much more room for further development.Publication Metadata only A statistical approach to control particle size of poly(acrylic acid) stabilized iron oxide nanoparticles(Routledge, 2006) N/A; N/A; Department of Chemistry; Department of Chemistry; Acar, Havva Funda Yağcı; Demirer, Miray; Faculty Member; Undergraduate Student; Department of Chemistry; College of Sciences; College of Sciences; 178902; N/APoly(acrylic acid) coated superparamagnetic iron oxide nanoparticles were prepared in aqueous solutions of iron salts with in situ coating of poly(acrylic acid). Influence of reaction variables, namely, iron concentration, reactive(COOH)/iron mole ratio, base (NH4OH) amount and polymer molecular weight, primarily on hydrodynamic size and stability of the particles was investigated. Also, size and stability of washed particles (no excess coating material) and magnetization as a function of these variables were studied. In order to design best set of experiments and correlate the results to variables, statistics programs Design Expert 7.0 and Minitab14 were used. Results will be discussed in this paper.Publication Metadata only A universal method for the preparation of magnetic and luminescent hybrid nanoparticles(American Chemical Society (ACS), 2010) Topal, Uğur; N/A; N/A; Department of Chemistry; Kaş, Recep; Sevinç, Esra; Acar, Havva Funda Yağcı; Master Student; Master Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 178902Hybrid nanoparticles (MDOTs) composed of luminescent quantum dots (QDs) and superparamagnetic iron oxides (SPIOs) were prepared by the ligand-exchange mechanism in a simple and versatile extraction method. In this method, aqueous QDs (CdS or CdTe) coated with carboxylated ligands exchange the fatty acid (lauric acid) coating of SPIOs in a water chloroform extraction process. QDs form a coating around SPIOs and transfer them into the aqueous phase in high efficiency. The method worked successfully with both small and polymeric coating molecules selected as cysteine, 2-mercaptopropionic acid, and a poly(acrylic acid)/mercaptoacetic acid mixture. The original properties of the nanoparticles were well-preserved in the hybrid structures: All MDOTS showed ferrofluidic behavior and had a luminescence in the original color of the QD. Magnetic properties and the luminesence intensity of MDOTs can be easily tuned with the SPIO/QD ratio. All particles are small and show very good stability (optical and colloidal) over months. For stable MDOTs with good luminescence properties, highly luminescent aqueous QDs (CdS or CdTe) with the mentioned coatings were prepared. The first examples of CdTe coated with 2MPA emitting from green to red and CdTe-PAA/MAA were provided as well.Publication Metadata only A water-soluble Irgacure 2959-based diallylammonium salt system for antibacterial coatings(Wiley, 2024) Balaban, Burcu; Avci, Duygu; Department of Chemistry; Güner, Pınar Tatar; Acar, Havva Funda Yağcı; Department of Chemistry; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of SciencesA water-soluble mixture of a novel diallylammonium salt photoinitiator based on 2-hydroxy-1-[4-(2-hydroxyethoxy) phenyl]-2-methyl-1-propanone (Irgacure 2959 or I2959) and diallylammonium tosylate has been prepared. It shows excellent water-solubility of 6.8 wt% in water, much greater than the solubility of I2959 (<2 wt%). It has a strong absorbance at 269 nm (epsilon similar to 15731) in methanol. It exhibits 15.6 times higher migration stability than I2959 due to its monomeric nature. Its photoinitiating efficiency of 2-hydroxyethylmethacrylate (HEMA) and poly(ethylene glycol) diacrylate (PEGDA, M-n = 575 D) was found to be similar to I2959. PEGDA hydrogels prepared using the synthesized photoinitiator (PI) were found to have highly porous structures (15.44 mu m) compared with those using I2959. PEGDA film prepared using this PI has demonstrated antibacterial properties against gram-negative Pseudomonas aeruginosa (ATCC 15442) and gram-positive Staphylococcus aureus (ATCC 23235) bacterial species.Publication Metadata only 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; 178902Aqueous 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.Publication Metadata only Alendronate-functionalized poly(amido amine) cryogels of high-toughness for biomedical applications(Elsevier Sci Ltd, 2020) Guven, Melek Naz; Altuncu, Seckin; Gulyuz, Umit; Okay, Oguz; N/A; Department of Chemistry; Demirci, Gözde; Acar, Havva Funda Yağcı; Master Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 178902Novel bisphosphonic acid-functionalized poly(amido amine) (PAA) macromers were synthesized through aza-Michael addition of sodium alendronate (ALE) and 5-amino-1-pentanol (AP) to N,N'-methylene bisacrylamide at two different molar ratios, with macmmer only having AP as comparison control. The macromers were photopolymerized to cryogels whose swelling, biodegradation and mineralization properties were studied. Biodegradation was most strongly affected by the macromer molecular weight. In mineralization studies, the control cryogel nucleated HAP, the others another type of biological apatite; the extent of mineralization depending on ALE concentration. Cryogel-apatite composites were studied by SEM, FTIR, XRD and thermogravimetric analysis. Mechanical tests reveal compressions up to 97% for cryogels, showing their high toughness. Young's modulus and compressive fracture stress increase with ALE content to 10 kPa and 2.2 +/- 0.4 MPa, respectively. The modulus increased significantly in mineralization due Ca2+-ALE bindings forming physical cross-links. Degradation products of ALE-containing cryogels showed dose, composition and cell type dependent cytotoxicity when incubated with osteosarcoma cells lines, Saos-2 and U-2 OS, and healthy C2C12 muscle cells.Publication Metadata only An experimental study on heat transfer performance of iron oxide based ferrofluids(ASME, 2012) Kaya, Alihan; Kurtoglu, Evrim; Kosar, Ali; Department of Chemistry; Acar, Havva Funda Yağcı; Faculty Member; Department of Chemistry; College of Sciences; 178902Nanofluids are colloidal compounds, where the solid phase material is composed of nano sized particles, and the liquid phase can potentially be any fluid but aqueous media are common. As a common nanofluid type, ferrofluids are formed by holding solid nanoparticles in suspension by weak intermolecular forces and may be produced from materials with different magnetic properties. Magnetite is one of the materials used for its natural ferromagnetic properties. Heat transfer performance of ferrofluids is one of the crucial properties among many others that should be analyzed and considered for their wide range of applications. For this purpose, experiments were conducted in order to characterize heat transfer properties of ironoxide based ferrofluids flowing through a microchannel. Promising results were obtained from this study, which are suggesting the use of ferrofluids for heat transfer applications can be advantageous.Publication Metadata only Anticancer use of nanoparticles as nucleic acid carriers(Amer Scientific Publishers, 2014) Gozuacik, D.; Akkoc, Y.; Kosar, A.; Dogan-Ekici, A. Isin; Ekici, Sinan; Department of Chemistry; Acar, Havva Funda Yağcı; Faculty Member; Department of Chemistry; College of Sciences; 178902Advances in nanotechnology opened up new horizons in the field of cancer research. Nanoparticles made of various organic and inorganic materials and with different optical, magnetic and physical characteristics have the potential to revolutionize the way we diagnose, treat and follow-up cancers. Importantly, designs that might allow tumor-specific targeting and lesser side effects may be produced. Nanoparticles may be tailored to carry conventional chemotherapeutics or new generation organic drugs. Currently, most of the drugs that are commonly used, are small chemical molecules targeting disease-related enzymes. Recent progress in RNA interference technologies showed that, even proteins that are considered to be "undruggable" by small chemical molecules, might be targeted by small RNAs for the purpose of curing diseases, including cancer. In fact, small RNAs such as siRNAs, shRNAs and miRNAs can drastically change cellular levels of almost any given disease-associated protein or protein group, resulting in a therapeutic effect. Gene therapy attempts were failing mainly due to delivery viral vector-related side effects. Biocompatible, non-toxic and efficient nanoparticle carriers raise new hopes for the gene therapy of cancer. In this review article, we discuss new advances in nucleic acid and especially RNA carrier nanoparticles, and summarize recent progress about their use in cancer therapy.Publication Metadata only Apoptosis induction by 2-mercaptopropionic acid (2-MPA)-coated silver sulfide QD in human A549 cells(Elsevier, 2017) Vardar, Deniz Özkan; Aydın, Sevtap; Başaran, Nurşen; N/A; Department of Chemistry; Hocaoğlu, İbrahim; Acar, Havva Funda Yağcı; PhD Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 178902N/APublication Metadata only Bidisperse magneto-rheological fluids consisting of functional SPIONs added to commercial MRF(Elsevier Science inc, 2020) N/A; N/A; Department of Chemistry; Department of Chemistry; Nejatpour, Mona; Ünal, Uğur; Acar, Havva Funda Yağcı; PhD Student; Faculty Member; Faculty Member; Department of Chemistry; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; 42079; 178902Magnetorheological fluids (MRFs) are smart materials with a reversible and fast transition from a liquid to a semi-solid state when an external magnetic field is applied (magnetorheological effect). the sedimentation of micron-sized magnetic particles in commercial MRFs is a crucial problem limiting the long-term use in industrial applications. Here, we develop a new MRF based on commercial 140-CG LORD (R) with the addition of surface functional superparamagnetic iron oxide nanoparticles (SPIons). these new bidisperse MRFs are comprised of either poly(acrylic acid) (Paa) coated SPIons or lauric acid (La) coated SPIons and micron-sized fatty acid-coated magnetic particles of the commercial MRF. SPIons have specific coatings to interact with the fatty acid coating of the micron-sized Fe-particles. Sedimentation behaviour and the magnetorheological properties of these bidisperse MRFs with 6-12 wt % SPIon were examined. Bidisperse MRFs improved the stability and redispersibility of MRFs. Bidisperse MRFs with 12 wt% SPIon-Paa showed similar or better magnetorheological behaviour than the commercial MRF despite lower content of the micron size Fe-particles. Hence, A combination of magnetizable nano and micron-sized particles and utilization of correct surface chemistry that allows their favourable interaction improves the stability of MRFs without sacrificing magnetic response but even by improving it.Publication Metadata only Bidisperse magnetorheological fluids with strong magnetorheological response, long-term stability and excellent in-use performance(IOP Publishing Ltd, 2024) Department of Chemistry;Department of Mechanical Engineering; Nejatpour, Mona; Saleh, Mostafa Khalil Abdou; Ulasyar, Abasin; Ünal, Uğur; Lazoğlu, İsmail; Acar, Havva Funda Yağcı; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Manufacturing and Automation Research Center (MARC); Graduate School of Sciences and Engineering; College of Sciences; College of EngineeringThere is a critical demand for magnetorheological fluids (MRFs) with high particle loading, long-term stability, and high magneto-viscous properties to be used in industrial MRF devices. Bidisperse MRFs composed of highly magnetizable micron-sized carbonyl iron particles and poly(acrylic acid) coated superparamagnetic iron oxide nanoparticles (SPIONs-PAA) that can chemically interact are proposed to achieve such MRFs, here. Coating bare, commercial CI with lauric acid (LA) enhanced its dispersibility in a hydrophobic carrier fluid, allowed high magnetic loading and significantly prevented the sedimentation of the particles when mixed with 9-12 wt% SPION. Different carrier fluids (mineral oil, paraffin, and hydraulic oil) were tested, and hydraulic oil was determined as the best for this particle combination. The most stable bidisperse MRF was achieved at 83%-84% magnetic content with 12 wt-%SPION-PAA, LA-coated-CI and 3 wt% polyvinyl alcohol. Such MRFs outperformed the commercial benchmark, 140-CG (R) from Lord Corp., in long-term stability (4 months) and stability under dynamic loading. Bidisperse MRFs were stable between 20 degrees C and 60 degrees C. Most importantly, the excellent performance of the bidisperse MRFs in dampers designed for washing machines suggests that these MRFs may provide comparable damping forces with much better stability, ensuring longer shelf-life and longer lifetime in use.Publication Metadata only (Bis)phosphonic acid-functionalized poly(ethyleneimine)- poly(amido amine)s for selective in vitro transfection of osteosarcoma cells(Amer Chemical Soc, 2021) Güven, Melek Naz; Altuncu, Seçkin; Konca, Yeliz Utku; Avcı, Duygu; N/A; Department of Chemistry; Demirci, Gözde; Acar, Havva Funda Yağcı; Master Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 178902Osteosarcoma is aggressive bone cancer, whose treatment has not changed significantly for the past few decades. Although gene therapy methods have emerged as potential treatment routes, the need for efficient and nontoxic gene delivery systems targeting osteosarcoma cells remains a challenge. High-molecular-weight poly(ethyleneimine)s (PEIs) are used as universal transfection agents; however, they cause significant cytotoxicity. on the other hand, poly(amido amine)s (PAAs) are biocompatible, biodegradable polymers with promising transfection efficiency, which should be improved further. In this paper, we combined low-molecular-weight branched PEI (1800 Da) and PAA macromers functionalized with various amounts of (bis)phosphonic acid groups and pentanol (via 5-amino-1-pentanol (AP)). The (bis)phosphonic acid groups on these polymers (PAEIs) are intended to facilitate bone targeting. The molecular weights of the PAEI polymers were between 2600 and 8600 g/mol. Their cytotoxicities and green fluorescence protein (GFP) transfection efficiencies were tested on an osteosarcoma cell line (U-2 OS cells), which is challenging to transfect, and healthy muscle cells (C2C12). Both the cytotoxicity and transfection efficiency of PAEIs were affected by the phosphonic acid (via APA, 2-aminoethyl phosphonic acid) or bisphosphonic acid (via ALE, sodium alendronate) content of the polymers. PAEIs are more cytocompatible than both linear and branched 25 kDa PEI. ALE-containing PAEIs provided better transfection than APA-containing ones. The most efficient PAEI polymer, containing a 0.7:0.3 AP/ALE ratio, displayed a transfection efficiency that was five times higher than that of 25 kDa PEI with dramatically better cytocompatibility. This is comparable to FuGENE, but PAEI is more advantageous in selective transfection of the U-2 OS. This set of polymers may be promising candidates for targeted gene therapy of osteosarcoma.Publication Metadata only Bisphosphonate-functionalized poly(amido amine) crosslinked 2-hydrox-yethyl methacrylate hydrogel as tissue engineering scaffold(Elsevier, 2021) Güven, Melek Naz; Balaban, Burcu; Okay, Oğuz; Avcı, Duygu; N/A; Department of Chemistry; Demirci, Gözde; Acar, Havva Funda Yağcı; Master Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 178902The first water soluble, bisphosphonate (BP, not bisphosphonic acid)-functionalized poly(amido amine) macromer (PAA-BP) is synthesized and used as a crosslinker for synthesis of a biodegradable and biocompatible hydrogel for tissue engineering scaffolds. The synthesis of PAA-BP is performed in three steps, the first two giving the control macromers (PAA-NHBoc and PAA-NH2): i) Michael addition reaction of N,N'-methylene bisacrylamide and N-Boc-1,6-hexanediamine (acrylamide/amine ratios of 1.2), ii) deprotection of Boc-protected amine groups, iii) Michael addition reaction of the amine groups with tetraethyl vinylidene bisphosphonate. The degree of BP substitution is 50% and molecular weight of the PAA-BP macromer is found to be 4800 g/mol. These macromers are incorporated into hydrogels by copolymerization with 2-hydroxyethyl methacrylate and the influence of bisphosphonate functionality on hydrogel properties; degradation, swelling, mechanical and mineralization, is investigated. The mineralization abilities, hence the mechanical properties of the hydrogels are strongly influenced by the BP functionality; PAA-BP forming strong (E = 83 +/- 1 kPa) hydrogel-apatite composites, PAA-NH2 also working to a lesser degree (E = 54 +/- 3 kPa). Cytocompatibility of the hydrogels is observed on Saos-2 human osteosarcoma, U-2 OS human bone osteosarcoma epithelial, C2C12 mouse myoblast muscle and NIH mouse embryonic fibroblast 3T3 cells. PAA-BP crosslinked hydrogels facilitate adhesion of C2C12 cells after mineralization. In summary, BP-functionalized hydrogel may have a potential impact on bone tissue engineering.Publication Metadata only Bisphosphonate-functionalized poly(β-amino ester) network polymers(Wiley, 2017) Güven, Melek Naz; Altuncu, Merve Seçkin; Eren, Tuğce Nur; Avcı, Duygu; N/A; Department of Chemistry; Acar, Havva Funda Yağcı; Duman, Fatma Demir; PhD Student; Faculty Member; Department of Chemistry; Graduate School of Science and Engineering; College of Sciences; N/A; 178902Three novel bisphosphonate-functionalized secondary diamines are synthesized and incorporated into poly(beta-amino ester)s (PBAEs) to investigate the effects of bisphosphonates on biodegradation and toxicity of PBAE polymer networks. These three novel amines, BPA1, BPA2, and BPA3, were prepared from the reactions of 1,4-butanediamine, 1,6-hexanediamine, or 4,9-dioxa-1,12-dodecanediamine with tetraethyl vinylidene bisphosphonate, respectively. The PBAE macromers were obtained from the aza-Michael addition reaction of these amines to 1,6-hexane diol diacrylate (HDDA) and poly(ethylene glycol) diacrylate (PEGDA, M-n=575) and photopolymerized to produce biodegradable gels. These gels with different chemistries exhibited similar degradation behavior with mass loss of 53-73% within 24 h, indicating that degradation is mostly governed by the bisphosphonate group. Based on the in vitro cytotoxicity evaluation against NIH 3T3 mouse embryonic fibroblast cells, the degradation products do not exhibit significant toxicity in most cases. It was also shown that PBAE macromers can be used as cross-linkers for the synthesis of 2-hydroxyethyl methacrylate hydrogels, conferring small and customizable degradation rates upon them. The materials reported have potential to be used as nontoxic degradable biomaterials. (C) 2017 Wiley Periodicals, Inc.Publication Open Access Broad spectrum antibacterial photodynamic and photothermal therapy achieved with indocyanine green loaded SPIONs under near infrared irradiation(Royal Society of Chemistry (RSC), 2020) N/A; Department of Physics; Department of Chemistry; Bilici, Kübra; Ataç, Nazlı; Muti, Abdullah; Toker, Işınsu Baylam; Doğan, Özlem; Sennaroğlu, Alphan; Can, Füsun; Acar, Havva Funda Yağcı; Researcher; 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); Graduate School of Sciences and Engineering; Graduate School of Health Sciences; School of Medicine; College of Sciences; N/A; N/A; N/A; N/A; 170418; 23851; 103165; 178902Antimicrobial photodynamic therapy (aPDT) and antimicrobial photothermal therapy (aPTT) are promising local and effective alternative therapies for antibiotic resistant bacterial infections and biofilms. A combination of nanoparticles and organic photosensitizers offers a great opportunity to combine PDT and PTT for effective eradication of both planktonic bacteria and their biofilms. In this work, photo-induced antibacterial activity of indocyanine green (ICG), 3-aminopropylsilane coated superparamagnetic iron oxide nanoparticles (APTMS@SPIONs) and ICG loaded APTMS@SPIONs was evaluated on planktonic cells and biofilms of Gram-negative (E. coli,K. pneumoniae,P. aeruginosa) and Gram-positive (S. epidermis) bacteria. A relatively low dose of ICG (25 mu g mL(-1)) and SPIONs (0.425 mu g mL(-1)nanoparticle) in combination with single, short (10 min) laser irradiation at 808 nm with a power of 1150 mW was used in this study. No dark toxicity of the agents or antibacterial effect of the laser irradiation was observed. The charge of the particles did not provide a significant difference in their penetration to Gram-negativeversusGram-positive bacterial strains or their biofilms. APTMS@SPION/laser treatment completely eliminatedP. aeruginosaand provided 7-log reduction in the colony forming unit (CFU) ofE. Coli, but was not effective on the other two bacteria. This is the first example for antibacterial phototoxicity of this nanoparticle. ICG/laser and ICG-APTMS@SPION/laser treatments provided complete killing of all planktonic cells. Successful eradication of all biofilms was achieved with ICG/laser (3.2-3.7 log reduction in CFUs) or ICG-APTMS@SPION/laser treatment (3.3-4.4 log reduction in CFUs). However, an exceptionally high, 6.5-log reduction as well as a dramatic difference between ICGversusICG/APTMS@SPION treatment was observed inK. pneumoniaebiofilms with ICG-APTMS@SPION/laser treatment. Investigation of the ROS production and increase in the local temperature of the biofilms that were subjected to phototherapy suggested a combination of aPTT and aPDT mechanisms for phototoxicity, exhibiting a synergistic effect when ICG-APTMS@SPION/laser was used. This approach opens an exciting and novel avenue in the fight against drug resistant infections by successfully utilizing the antimicrobial and antibiofilm activity of low dose FDA approved optically traceable ICG and relatively low cost clinically acceptable iron oxide nanoparticles to enable effective aPDT/aPTT combination, inducedviashort-duration laser irradiation at a near-infrared wavelength.Publication Metadata only Bypassing pro-survival and resistance mechanisms of autophagy in EGFR-positive lung cancer cells by targeted delivery of 5FU using theranostic Ag2S quantum dots(Royal Soc Chemistry, 2019) Akkoç, Yunus; Gözüaçık, Devrim; N/A; N/A; N/A; N/A; Department of Physics; Department of Chemistry; Demirci, Gözde; Duman, Fatma Demir; Bavili, Nima; Kiraz, Alper; Acar, Havva Funda Yağcı; PhD Student; Master 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; School of Medicine; College of Sciences; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); N/A; N/A; N/A; 22542; 178902Targeted drug delivery systems that combine imaging and therapeutic functions in a single structure have become very popular in nanomedicine. Near-infrared (NIR) emitting Ag2S quantum dots (QDs) are excellent candidates for this task. Here, we have developed PEGylated Ag2S QDs functionalized with Cetuximab (Cet) antibody and loaded with an anticancer drug, 5-fluorouracil (5FU). These theranostic QDs were used for targeted NIR imaging and treatment of lung cancer using low (H1299) and high (A549) Epidermal Growth Factor Receptor (EGFR) overexpressing cell lines. The Cet conjugated QDs effectively and selectively delivered 5FU to A549 cells and provided significantly enhanced cell death associated with apoptosis. Interestingly, while treatment of cells with free 5FU activated autophagy, a cellular mechanism conferring resistance to cell death, these EGFR targeting multimodal QDs significantly overcame drug resistance compared to 5FU treatment alone. The improved therapeutic outcome of 5FU delivered to A549 cells by Cet conjugated Ag2S QDs is suggested as the synergistic outcome of enhanced receptor mediated uptake of nanoparticles, and hence the drug, coupled with suppressed autophagy even in the absence of addition of an autophagy suppressor.Publication Metadata only CdS-oleic acid quantum dots as long-wavelength photoinitiators in organic solvent and preparation of luminescent, colloidal CdS/polymer nanocomposites(2018) Morlet-Savary, Fabrice; Lalevee, Jacques; N/A; Department of Chemistry; Buz, Enes; Acar, Havva Funda Yağcı; Master Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 178902Photoexcitation of luminescent semiconductor quantum dots (QDs) generates an electron–hole pair, which can be utilized for photoinitiation of radical polymerization reactions. Here, oleic acid coated CdS QDs (CdS–OA) are demonstrated as successful photoinitiators in the absence of a protic solvent or a hole scavenger for the first time. This provides photopolymerization of hydrophobic methyl methacrylate in toluene, providing colloidal and strongly luminescent CdS/poly(methacrylic acid) (PMMA) hybrid structures with improved stability of the CdS. Besides, successful photopolymerization of poly(ethylene glycol)diacrylate at different excitation windows (320–480 and 400–500 nm) is demonstrated. This indicates that CdS–OA can act as a long-wavelength initiator. Electron spin resonance (ESR) studies and control experiments suggest decarboxylation of the oleic acid as the initial source of the free radical. This method represents a unique and very simple way to create luminescent, small, stable, and colloidal QD/polymer hybrids.