Irem Kosif
University of Massachusetts Amherst
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Publication
Featured researches published by Irem Kosif.
Molecular Pharmaceutics | 2013
Samantha McRae Page; Molly Martorella; Sangram S. Parelkar; Irem Kosif; Todd Emrick
A series of block copolymers based on 2-methacryloyloxyethyl phosphorylcholine (MPC) were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Incorporation of dihydrolipoic acid (DHLA) into the hydrophobic block led to formation of block copolymer micelles in water. The micelles were between 15 and 30 nm in diameter, as characterized by dynamic light scattering (DLS), with some size control achieved by adjusting the hydrophobic/hydrophilic balance. Cross-linked micelles were prepared by disulfide formation, and observed to be stable in solution for weeks. The micelles proved amenable to disassembly when treated with a reducing agent, such as dithiothreitol (DTT), and represent a potential delivery platform for chemotherapeutic agents. As a proof-of-concept, camptothecin (CPT) was conjugated to the polymer scaffold through a disulfide linkage, and release of the drug from the micelle was monitored by fluorescence spectroscopy. These CPT-loaded prodrug micelles showed a reduction in release rate compared to physically encapsulated CPT. The use of disulfide conjugation facilitated drug release under reducing conditions, with a half-life (t1/2) of 5.5 h in the presence of 3 mM DTT, compared to 28 h in PBS. The toxicity of the micellar prodrugs was evaluated in cell culture against human breast (MCF7) and colorectal (COLO205) cancer cell lines.
Scientific Reports | 2015
Jerome Carnis; Wonsuk Cha; James Wingert; Jinback Kang; Zhang Jiang; Sanghoon Song; Marcin Sikorski; C. Gutt; San-Wen Chen; Yeling Dai; Yicong Ma; Hongyu Guo; L. B. Lurio; Oleg Shpyrko; Suresh Narayanan; Mengmeng Cui; Irem Kosif; Todd Emrick; Thomas P. Russell; Hae Cheol Lee; Chung-Jong Yu; G. Grübel; Sunil K. Sinha; Hyunjung Kim
The recent advent of hard x-ray free electron lasers (XFELs) opens new areas of science due to their exceptional brightness, coherence, and time structure. In principle, such sources enable studies of dynamics of condensed matter systems over times ranging from femtoseconds to seconds. However, the studies of “slow” dynamics in polymeric materials still remain in question due to the characteristics of the XFEL beam and concerns about sample damage. Here we demonstrate the feasibility of measuring the relaxation dynamics of gold nanoparticles suspended in polymer melts using X-ray photon correlation spectroscopy (XPCS), while also monitoring eventual X-ray induced damage. In spite of inherently large pulse-to-pulse intensity and position variations of the XFEL beam, measurements can be realized at slow time scales. The X-ray induced damage and heating are less than initially expected for soft matter materials.
Nano Letters | 2017
Mengmeng Cui; Caroline Miesch; Irem Kosif; Huarong Nie; Paul Kim; Hyunki Kim; Todd Emrick; Thomas P. Russell
Nanoparticles (NPs) segregated to the liquid/liquid interface form disordered or liquid-like assemblies that show diffusive motions in the plane of the interface. As the areal density of NPs at the interface increases, the available interfacial area decreases, and the interfacial dynamics of the NP assemblies change when the NPs jam. Dynamics associated with jamming was investigated by X-ray photon correlation spectroscopy. Water-in-toluene emulsions, formed by a self-emulsification at the liquid/liquid interface and stabilized by ligand-capped CdSe-ZnS NPs, provided a simple, yet powerful platform, to investigate NP dynamics. In contrast to a single planar interface, these emulsions increased the number of NPs in the incident beam and decreased the absorption of X-rays in comparison to the same path length in pure water. A transition from diffusive to confined dynamics was manifested by intermittent dynamics, indicating a transition from a liquid-like to a jammed state.
Advanced Materials Interfaces | 2016
Chia Chih Chang; Kristopher W. Kolewe; Yinyong Li; Irem Kosif; Benny D. Freeman; Kenneth R. Carter; Jessica D. Schiffman; Todd Emrick
Angewandte Chemie | 2012
Caroline Miesch; Irem Kosif; Eunji Lee; Jung Keun Kim; Thomas P. Russell; Ryan C. Hayward; Todd Emrick
Polymer | 2009
Beom-Young Ryu; SungCheal Moon; Irem Kosif; T. Ranganathan; Richard J. Farris; Todd Emrick
Angewandte Chemie | 2013
Irem Kosif; Mengmeng Cui; Thomas P. Russell; Todd Emrick
Advanced Materials Interfaces | 2014
Irem Kosif; Chia Chih Chang; Ying Bai; Alexander E. Ribbe; Anna C. Balazs; Todd Emrick
ACS Nano | 2017
Irem Kosif; Katrina Kratz; Siheng Sean You; Mrinal K. Bera; Kyungil Kim; Brian Leahy; Todd Emrick; Ka Yee C. Lee; Binhua Lin
Bulletin of the American Physical Society | 2014
Xiaobo Shen; Irem Kosif; Todd Emrick; D. Venkataraman; Thomas P. Russell