I.C. Reynhout

Synthesis of polymer-biohybrids: from small to giant surfactants

Amphiphiles or surfactants, more popularly known as soaps, are among the oldest known chemical compounds used by man. Written text on a clay tablet dated to 2200 B.C. indicates that the Babylonians were familiar with soap-like substances. According to the Ebers papyrus (1550 B.C.), the ancient Egyptians bathed regularly in a mixture of animal oils, vegetable extracts, and alkaline salts, and a soap factory with bars of scented soap was found in the ruins of Pompeii (79 A.D.). In modern times, the use of soap has become universal, and we now understand reasonably well what happens when soap molecules are dispersed in aqueous solution and how the cleaning properties of soap work. The latter is related to the surface-active behavior of soap molecules, which is a result of their amphiphilic, also called amphipathic, character. Although the cleaning aspect is still an important issue, scientists are increasingly focusing on other properties of soaps, for example, self-assembling behavior and how this can be used in the design and non-covalent synthesis of new (macro)molecular architectures. These new molecules can be employed in nanotechnology and drug delivery, among other applications. This Account will focus on three different classes of amphiphiles. The first is the low molecular weight amphiphiles, also called classical amphiphiles in this context. A short overview will be given on the research carried out by our group and others on the self-assembly behavior and properties of these compounds; in particular, we focus on the ones that can be stabilized by polymerization (polymerized vesicles). Next, we will introduce the still relatively young field of superamphiphiles, macromolecules consisting of a hydrophobic and a hydrophilic polymeric block. Finally, and this constitutes the main part of this Account, we will provide an overview of a new class of amphiphiles, the so-called giant amphiphiles. These macromolecules have an enzyme or protein as the polar head group and a hydrophobic polymer as a tail. We will finish the Account with conclusions and an outlook to the future.

Cascade Reactions in an All‐Enzyme Nanoreactor

Good things come in small packages! Giant amphiphiles, consisting of a polymeric hydrophobic tail and a horseradish peroxidase head, were simultaneously synthesized and self-assembled into vesicles. During the self-assembly process, glucose oxidase was encapsulated to create enzymatic cascade nanoreactors (see picture; ABTS= 2,2′-azido-bis(3-ethylbenzthiazoline-6-sulfonic acid)).

Solid phase synthesis of biohybrid block copolymers

A new versatile route to synthesise biohybrid block copolymers is presented in which an amine terminated polymer is attached to an aldehyde functionalised resin, from which in subsequent steps the desired peptide can be grown using standard procedures.

Nanoscale organization of proteins via block copolymer lithography and non-covalent bioconjugation

Thin films of cylinder-forming biotinylated poly(ethylene glycol)-polystyrene (PEG-b-PS) block copolymers were studied as a means to produce protein patterns. The orientation of the PEG cylinders depended on the end group functionality as well as on the preparation conditions. In the case of perpendicular cylinders, immobilization of single streptavidin molecules could be achieved. This immobilization was controlled by varying the amount of biotin in the films by mixing with non-functional PEG-b-PS.