Colloids and Surfaces A: Physicochem. Eng. Aspects 445 (2014) 40–47 Contents lists available at ScienceDirect Colloids and Surfaces A: Physicochemical and Engineering Aspects jo ur nal ho me p ag e: www.elsevier.com/locate/colsurfa Boronic acid functionalized polymeric microspheres for catecholamine isolation Nalan Özdemir ∗ , Ays ¸ e C ¸ akır, Burcu Somtürk Chemistry Department, Faculty of Science, Erciyes University, TR-38039 Kayseri, Turkey h i g h l i g h t s • 3-Aminophenyl boronic acid functionalized-poly(3-chloro-2- hydroxypropyl methacrylate) [APBA functionalized-poly(HPMA-Cl)] microspheres. • A new sorbent for catecholamine iso- lation. • The reversible catecholamine binding behavior of the APBA functionalized- poly(HPMA-Cl) microspheres. g r a p h i c a l a b s t r a c t a r t i c l e i n f o Article history: Received 1 October 2013 Received in revised form 2 January 2014 Accepted 6 January 2014 Available online 15 January 2014 Keywords: Catecholamines Boronate affinity technique Aminophenyl boronic acid Polymeric microspheres Suspension polymerization a b s t r a c t In this study, 3-aminophenyl boronic acid functionalized-poly(3-chloro-2-hydroxypropyl methacrylate) [APBA functionalized-poly(HPMA-Cl)] microspheres were prepared and characterized as a new alterna- tive sorbent for catecholamine isolation. Chloropropyl group containing poly(HPMA-Cl) microspheres were synthesized in spherical gel form with a suspension polymerization technique, and it is followed by the APBA conjugation to the poly(HPMA-Cl) microspheres through amide bond formation. After- wards, for the characterization of the prepared microspheres, SEM images were taken and FTIR analysis was performed. Furthermore, to determine APBA content of prepared microspheres, nitrogen analysis was performed and the amount of APBA was calculated as 94.6 mg APBA/g microsphere. The aver- age size of the APBA functionalized-poly(HPMA-Cl) microspheres was calculated as 205 ± 35 m. The reversible catecholamine (dopamine, epinephrine and norepinephrine) binding behavior of the APBA functionalized-poly(HPMA-Cl) and poly(HPMA-Cl) microspheres was investigated in batch fashion type. In the reversible catecholamine binding experiments, the maximum equilibrium binding was obtained at pH 8.5 which is very close to the pK a of boronic acid, therefore all the experiments were carried out at this pH. While no-significant non-specific binding was observed onto the non-functionalized microspheres, the maximum catecholamine binding capacities of the APBA functionalized-poly(HPMA-Cl) microspheres were found as 61 mg, 7 mg and 8 mg per gram of microsphere for dopamine, epinephrine and norepi- nephrine, respectively. All three of the catecholamines were released from the microspheres with the yields higher than 90% by weight. The obtained results indicated that APBA functionalized-poly(HPMA- Cl) microspheres are promising sorbents that can be used for the efficient isolation of catecholamines. © 2014 Published by Elsevier B.V. ∗ Corresponding author. Tel.: +90 352 207 66 66x33176; fax: +90 352 437 49 31. E-mail addresses: nalanoz dmr@hotmail.com, ozdemirn@erciyes.edu.tr (N. Özdemir), cakir.aysee@hotmail.com (A. C ¸ akır), burcu smtrk@hotmail.com (B. Somtürk). 1. Introduction Dopamine (DA), epinephrine (E) and norepinephrine (NE) are very well known adrenal hormones, which are also called cate- cholamines. They are a group of biogenic amines that also contain a 3,4-dihydroxy-substituted phenyl ring [1,2] and have a number 0927-7757/$ – see front matter © 2014 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.colsurfa.2014.01.005