Miniemulsion switchable electrolysis under constant current conditions

Abstract

Troxerutin, a naturally occurring flavonoid glycoside, has a variety of beneficial activities characteristic for flavonols, such as strong antioxidant and anti-inflammatory properties. Besides the beneficial effects of troxerutin, limitations such as bioavailability have disrupted its application and prompt scientists to look for effective modification methods. This work presents the synthesis of troxerutin-based macromolecules with lipophilic poly(n-butyl acrylate) (PnBA) star arms via "core-first" procedure in a two-step synthetic route. Troxerutin as a polyphenol structure with ubiquitous reactive hydroxyl groups was for the first time modified with α-bromoisobutyryl bromide to receive an atom transfer radical polymerization (ATRP) initiator with 10 brominated initiation sites. The further step involved the synthesis of novel star-like macromolecules with troxerutin core and PnBA star arms by simplified electrochemically mediated ATRP (seATRP) in an environmentally friendly reaction medium-miniemulsion. Electrolysis under constant current conditions with temporal control was implemented, resulting in well-defined star-like polymers with complete preservation of chain-end functionality after restarting the synthesis. Hydrophobic properties of received troxerutin-based macromolecules were investigated by contact angles (Θ) measurements, followed by the free surface energy (FSE) calculations.

Smart, Naturally-Derived Macromolecules for Controlled Drug Release

“…Hydroxyl groups located in troxerutin substrate were functionalized with α-bromoisobutyryl bromide (BriBBr) to form an ATRP initiator molecule as previously described in detail [ 35 ]. The supramolecular bromide initiator was subsequently polymerized with tert -butyl acrylate ( t BA)—an excellent substrate for receiving pH-responsive acrylic acid (AA) moieties in the proposed synthetic route.…”

“…These reagents were not subjected to further purification. Tris(2-pyridylmethyl)amine (TPMA) and Cu II Br 2 /TPMA catalyst complex were prepared as previously reported [ 35 , 52 ]. 2-Dimethylaminoethyl methacrylate (DMAEMA, >99%, Sigma-Aldrich) and tert -butyl acrylate ( t BA, >99%, Sigma-Aldrich) were passed through a column filled with basic alumina before use in order to remove inhibitor [ 53 ].…”

“…In order to receive biocompatible and biodegradable structures with great potential for use in live organisms by means of ATRP techniques, naturally-derived substrates are increasingly used as macromolecular cores [ 35 ]. Troxerutin is a natural bioflavonoid—a trihydroxyethylated derivative of rutin that can be found in tea, coffee, and a variety of fruits and vegetables [ 36 , 37 ].…”

“…Troxerutin is a natural bioflavonoid—a trihydroxyethylated derivative of rutin that can be found in tea, coffee, and a variety of fruits and vegetables [ 36 , 37 ]. As a polyphenol structure, it was successfully modified by the ATRP approach to enhance its lipophilicity and, thus, bioavailability, modifying it with hydrophobic poly( n -butyl acrylate) (P n BA) chains [ 35 ]. The presented work shows the facile route for the use of this naturally-derived flavonoid glycoside for preparing smart polymeric materials, namely pH-responsive polymers for controlled release in a live organism, both human or plants.…”

Stimuli-Responsive Rifampicin-Based Macromolecules

“…Among other RDRP techniques, it is recently the most influential approach in the preparation of precisely-defined polymer materials with complex architecture [ 24 , 25 ]. It was successfully applied for the synthesis of a wide range of branched architectures by modification of naturally-derived and bioactive structures, e.g., vitamins [ 17 , 26 , 27 ], sugars [ 28 , 29 ], tannins [ 30 , 31 ], drugs [ 32 ], and biopolymers [ 33 , 34 , 35 ], according to the “grafting from” approach, providing materials with predetermined structure for potential use in biomedical applications. The use of ATRP for drug modification is beneficial from several reasons, i.e., control of the polymer chain structure during polymerization resulting in materials with precise functionality, ability to receive ultra-pure products using “clean” techniques controlled by external stimulus e.g., electric current [ 36 , 37 , 38 ], ultrasound [ 39 , 40 , 41 ] and light [ 42 , 43 , 44 , 45 ], removing additional chemical reducing agents from reaction media; externally control methods allow for temporal control during polymerization, beneficial in the preparation of predetermined structures [ 17 , 27 , 36 ]; low ppm ATRP approaches use only ppm level of catalyst, easily removed from final products, without contamination of the product [ 46 , 47 ].…”