Organic Nano-Compartments as Biomimetic Reactors and Protocells

Abstract

In recent years, nanoscale self-assembled structures have attracted ever increasing attention because of their potential to act as molecular templates for the synthesis of novel materials, delivery vehicles for therapeutic agents, and compartments defined at the molecular level that provide environmental conditions conducive to specific chemical reactions. In this review, we will focus mostly on this latter application. Amphiphiles that self-assemble to yield nano-compartments such as micelles, reverse-micelles and liposomes, have been used to build nanoscale reactors that can effect chemical reactions through spatial co-localization of the reacting species. The reacting species may include the compartment building amphiphiles themselves. These nano-compartments provide not only the conditions for the reaction to occur, but also allow the buildup of complex reaction networks by retaining primary reaction products which may in turn be capable of additional reactions. Ultimately, such complex systems could also serve as starting points for minimal artificial cells, i.e. protocells which would be highly simplified versions of biological cells and which might be engineered for specific tasks related to therapeutic and diagnostic applications. We will report on advances in the design of these chemical self-assembled systems and the challenges that still lie ahead.

Interactions between Catalysts and Amphiphilic Structures and their Implications for a Protocell Model

“…[2,17] This concept should allow a remedy for some issues (e.g., permeability to charged solutes, encapsulation yields) encountered in the more commonly envisioned containers [1,7,18,18] that consist of the aqueous volume enclosed within vesicles.…”

Primitive Membrane Formation, Characteristics and Roles in the Emergent Properties of a Protocell

“…The emergent properties of often intricate reactive networks in relation to container structures is discussed without attempting an indepth survey of all implementations of liposomes and vesicles as bioreactors [2,51,52]. Systems where membrane support chemical reactions or reaction networks can be grouped in two broad categories: those where (i) the membranes themselves or the membrane enclosed aqueous volume serve as co-localization vessels and (ii) the membrane multiphase character is the foundation for a differentiated reaction set-up.…”

Membrane Self-Assembly Processes: Steps Toward the First Cellular Life

“…8.6), and general issues related to metabolism. (See Walde and Ichikawa (2001) or Monnard et al (2008) for a review of catalytic species entrapped in vesicular structures.) Three sources of energy could be harvested by primitive cells: chemical energy in the form of chemical bonds or oxidation-reduction reactions, and light energy (see Deamer 1997 for review).…”