Researcher: Pehlivan, Çiğdem
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Pehlivan, Çiğdem
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Publication Open Access Sulfide-capped InP/ZnS quantum dot nanoassemblies for a photoactive antibacterial surface(American Chemical Society, 2024) Vanalakar, Sharadrao; Alkan, Fahri; Department of Molecular Biology and Genetics;Department of Chemistry;Department of Chemical and Biological Engineering;Department of Electrical and Electronics Engineering; Khan, Saad Ullah; Sürme, Saliha; Eren, Güncem Özgün; Almammadov, Toghrul; Pehlivan, Çiğdem; Kaya, Lokman; Hassnain, Muhammad; Önal, Asım; Balamur, Rıdvan; Şahin, Afsun; Kölemen, Safacan; Kavaklı, İbrahim Halil; Nizamoğlu, Sedat; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Sciences and Engineering; College of Sciences; Graduate School of Health Sciences; School of Medicine; College of EngineeringSemiconductor photocatalysis has recently emerged as a promising method for microbial inactivation. So far, quantum dots have generally been investigated as antibacterial suspension. Instead, here we demonstrate a InP/ZnS quantum dot nanoassembly film against both Gram-negative and Gram-positive bacteria. For effective operation in the solid phase, a thin layer of ZnS shell was grown on InP QD and the native long-chain ligand of stearic acid was replaced with sulfide that led to a high quantum yield of superoxide generation as 4.9%. QDs are assembled onto solid surfaces through sequential dip coating of positively charged poly(diallyldimethylammonium chloride) and negatively charged QDs. These QD nanoassemblies demonstrate growth inhibition against Escherichia coli and multidrug-resistant Staphylococcus aureus under illumination. Interestingly, such an approach can be directly applied to irregular surfaces, as well. This study unveils the potential of the nanoengineering of QDs for antibacterial coatings.Publication Open Access Capacitive and efficient near-infrared stimulation of neurons via an ultrathin AgBiS2 nanocrystal layer(American Chemical Society, 2024) Oh, Jae Taek; Wang, Yongjie; Konstantatos, Gerasimos; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Balamur, Rıdvan; Karatüm, Onuralp; Önal, Asım; Kaleli, Humeyra Nur; Pehlivan, Çiğdem; Şahin, Afsun; Hasanreisoğlu, Murat; Nizamoğlu, Sedat; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Sciences and Engineering; Graduate School of Health Sciences; School of Medicine; College of EngineeringColloidal nanocrystals (NCs) exhibit significant potential for photovoltaic bioelectronic interfaces because of their solution processability, tunable energy levels, and inorganic nature, lending them chemical stability. Silver bismuth sulfide (AgBiS2) NCs, free from toxic heavy-metal elements (e.g., Cd, Hg, and Pb), particularly offer an exceptional absorption coefficient exceeding 10(5) cm(-1) in the near-infrared (NIR), surpassing many of their inorganic counterparts. Here, we integrated an ultrathin (24 nm) AgBiS2 NC layer into a water-stable photovoltaic bioelectronic device architecture that showed a high capacitive photocurrent of 2.3 mAcm(-2) in artificial cerebrospinal fluid (aCSF) and ionic charges over 10 mu Ccm(-2) at a low NIR intensity of 0.5 mWmm(-2). The device without encapsulation showed a halftime of 12.5 years under passive accelerated aging test and did not show any toxicity on neurons. Furthermore, patch-clamp electrophysiology on primary hippocampal neurons under whole-cell configuration revealed that the device elicited neuron firing at intensity levels more than an order of magnitude below the established ocular safety limits. These findings point to the potential of AgBiS2 NCs for photovoltaic retinal prostheses.