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Fluorophore Labelled Smart Polymers Saima Jabeen, Bruce.D. Alexander , Lisa Benee and Tammy Ehiwe School of Science, University of Greenwich at Medway, Chatham Maritime, Kent ME4 4TB, UK (js48@gre.ac.uk) Introduction Results and Discussion Materials and Synthesis Scheme 1. Coupling reaction between amine reactive fluorophore NFR and carboxylate microgel. References Smart polymers (microgels) belong to the class of synthetic polymers which offer unique physico-chemical properties mainly their ability to respond to the external stimuli e.g. pH and temperature. They are three dimensional, covalently cross-linked colloidal particles. The degree of internal cross-linking structures determines particle properties e.g. size, structural stability, and mechanical rigidity. This also facilitates the swelling and de-swelling behaviour of particles. Interest in such novel responsive polymers and their potential applications in multidisciplinary scientific fields has persisted particularly for the design and development of sensitive/responsive materials. 1 However, there are limitations to many of the techniques used to characterize the size and structure of microgels in a rapid, routine manner e.g. rheological measurements and swelling ratio measurements using microscopy. Microgels based on N- iso propylacrylamide (NIPAM) were synthesized and coupled with the amine reactive fluorescent ( e.g. Nuclear fast red {NFR dye}) probes using standard coupling chemistry. In this study, the coupling reaction is based on Grabarek and Gergely’s method. The coupling reagents used are 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC or EDAC) and N-hydroxysuccinimide (NHS) owing to their ability to conjugate carboxyl groups to primary amines to form amide bond (Scheme 1). [ 1] Roy, D.; Cambre, J.N.; Sumerlin, B.S. Prog. Polym. Sci . 2010 , 35 , 278-301. [2] Hoare, T.; Pelton. R. Curr. Opin. Colloid. In. 2008 , 13 , 413-428. [3] Grabarek, Z.; Gergely. J. Anal. Biochem. 1990 , 185 , 131-135. Characterization Techniques A number of analytical techniques have been employed to characterize the dye crosslinked microgel and are described below: 1. Dynamic Light Scatttering (DLS): measurements were performed using a Malvern Zetasizer Nano ZS in  -potential and size mode. 2. Fourier Transform Infrared spectroscopy (FTIR) : spectra (40 scans) were recorded on a Perkin Elmer Paragon 1000 FTIR spectrometer operating at a resolution of 1 cm -1 in the 450-4000 cm -1 range. 3. High Sensitivity-Differential Scanning Calorimetry (HS-DSC): measurements were taken with a Nano HS-DSC calorimeter at an external pressure of ca. 3 atm. The scan was carried out from 25-80 o C at the rate of 0.5 o C. 4. Fluorescence spectroscopy : emission spectra were recorded on a Cary eclipse instrument over a wavelength range of 200-900 nm Conclusions ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Objective Fluorescent methods have been previously used for the determination of three dimensional structures and conformational changes of microgels. 2 Two potential methods are: 1) adsorption of free fluorescent probe to polymer system through electrostatic attraction; 2) covalently bound fluorescent probe to polymer backbone. The aim of current project is to develop a novel synthetic method to label the smart polymer with fluorescent probes to determine the degree of internal cross-linking and conformational changes under different experimental conditions e.g. as a function of temperature and pH. ,[object Object],[object Object]

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