2018, Pretscher, Martin, Pineda-Contreras, Beatriz A., Kaiser, Patrick, Reich, Steffen, Schöbel, Judith, Kuttner, Christian, Freitag, Ruth, Fery, Andreas, Schmalz, Holger, Agarwal, Seema

Smart polymers are a valuable platform to protect and control the activity of biological agents over a wide range of conditions, such as low pH, by proper encapsulation. Such conditions are present in olive oil mill wastewater with phenol as one of the most problematic constituents. We show that elastic and pH-responsive diblock copolymer fibers are a suitable carrier for Corynebacterium glutamicum, i.e., bacteria which are known for their ability to degrade phenol. Free C. glutamicum does not survive low pH conditions and fails to degrade phenol at low pH conditions. Our tea-bag like biohybrid system, where the pH-responsive diblock copolymer acts as a protecting outer shell for the embedded bacteria, allows phenol degradation even at low pH. Utilizing a two-step encapsulation process, planktonic cells were first encapsulated in poly(vinyl alcohol) to protect the bacteria against the organic solvents used in the second step employing coaxial electrospinning.

2015, Liu, Fangyao, Jiang, Shaohua, Ionov, Leonid, Agarwal, Seema

Photo cross-linkable thermoresponsive polymers of UCST-type based on acrylamide (AAm) and acrylonitrile (AN) useful for preparing thermophilic hydrogel films and fibers are presented. The polymers prepared via free radical and reversible addition fragmentation chain-transfer (RAFT) polymerization methods using N-(4-benzoylphenyl)acrylamide (BPAm) as photo cross-linkable comonomers provided highly stable UCST-type phase transition in water reproducible without hysteresis for many cycles. The cloud point could be manipulated by varying the acrylonitrile amount in the feed. Chemically cross-linked hydrogel films and nanofibers (average diameter 500 nm) were successfully prepared from the ter-copolymers by solution casting and electrospinning followed by UV irradiation. These hydrogels showed a continuous positive volume transition behavior in water with increasing temperature that was utilized for the design of microactuators.