An innovative approach to prepare hypericin molecularly imprinted pearls using a “phyto-template” Ana-Mihaela Florea a,b,1 , Tanța-Verona Iordache b,1 , Catherine Branger c , Marius Ghiurea b , Sorin Avramescu d , Gheorghe Hubca a , Andrei Sârbu b,n a University Politehnica of Bucharest, The Faculty of Applied Chemistry and Materials Science, Bioresources and Polymer Science Department, 1-7 Polizu, 011061 Bucharest, Romania b National Research and Development Institute for Chemistry and Petrochemistry INCDCP-ICECHIM, Advanced Polymer Materials and Polymer Recycling, 202 Splaiul Independentei, 060021 Bucharest, Romania c Université de Toulon, Laboratoire MAPIEM, EA 4323, 83957 La Garde, France d University of Bucharest, Chemistry Faculty, 36-46 Mihail Kogalniceanu, 050107 Bucharest, Romania article info Article history: Received 19 August 2015 Received in revised form 20 October 2015 Accepted 22 October 2015 Available online 23 October 2015 Keywords: Phyto-template Hypericin Molecularly imprinted polymers Wet phase inversion Hypericum Perforatum extract Separation abstract In this paper, an innovative method that uses hypericin “phyto-template” molecules is being applied herein for the first time to produce molecularly imprinted polymer (MIP) pearls able to selectively retain hypericin from Hypericum Perforatum L primary extracts. For this purpose, the wet phase inversion method was preferred for preparing the hypericin-MIP pearls for several reasons referring to economical benefits but also due to the fact that hypericin “phyto-template” molecules can be generated along with the phase inversion of the copolymer. Practically, the precursor poly(acrylonitrile–co–methacrylic acid) solution was mixed with a purified and concentrated naphtodianthrone phyto-extract (consisting only of hypericin and pseudo-hypericin). In the subsequent phase inversion step hypericin was trapped in the copolymer droplets, as a result to its poor solubility in the inversion water bath, and further served as “phyto-template” in the imprinting step. This in situ repartition of hypericin and pseudo-hypericin was sustained by HPLC-DAD chromatograms which recorded only the presence of hypericin during the ex- traction stage of imprinted pearls. Batch rebinding measurements, all together, validated the efficiency of this innovative imprinting procedure. The hypericin rebinding of imprinted pearls was quantitative (up to 318 mg/L) and approximately 5 times more specific relative to the blank pearls. Competitive re-binding revealed a more selective behaviour of imprinted pearls for hypericin when the up-take was measured against pseudohypericin (selectivity coefficient above 4.50). & 2015 Elsevier B.V. All rights reserved. 1. Introduction Natural naphtodianthrone pigments occurring in Hypericum Perforatum (St. John’s Wort), particularly hypericin (H), have been extensively studied for their antidepressant, antitumor and anti- inflammatory properties [1]. Recently, several methods for naph- thodianthrones extraction were developed, including sonication, Soxhlet extraction, supercritical fluid extraction and pressurised liquid extraction [2–5]. Unfortunately, the majority of available protocols separate H and its structural derivate pseudohypericin (PH) all together. Frequently H and PH are referred to as hypericins or total naphtodianthrones (NTs). Though, several procedures for the separation of the two compounds currently exist, the commercial versions of H are at high reach and cost due to com- plex extractions and purification methods which require multiple cycles and fast handling of the materials [6]. Hence, this paper introduces an innovative idea for H separation which involves designing selective adsorbent pearls relying on the advantages of molecular imprinting techniques (MIT) [7,8]. Molecularly im- printed polymers (MIPs) are artificially designed sorbents with specific enhanced selectivity towards template structures. The tendency of designing and using synthetic mimetic materials over biological receptors has gradually increased [9–11] and became a modern technique to create selective sorbents [12–14] or sensors [15,16], due to their unique properties referring to durability, and superior mechanical and chemical stability [17,18]. The use of MIT also brings with it significant advantages i.e. low-medium com- plexity of synthesis and reduced preparation costs [19]. For the last two decades designing these imprinted materials for specific ap- plications has proven to be a serious challenge considering the multitude of approached procedures [20–29]. Concerning our Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/talanta Talanta http://dx.doi.org/10.1016/j.talanta.2015.10.061 0039-9140/& 2015 Elsevier B.V. All rights reserved. n Corresponding author. Fax: þ40 21 312 34 93. E-mail address: andr.sarbu@gmail.com (A. Sârbu). 1 Authors with equal contribution. Talanta 148 (2016) 37–45