"Here is where we have dreams and we encapsulate them!"
-M. Gill
-M. Gill
From Molecule to Macromolecule to "Supra-molecule"
Fig.1. Molecular engineering of nanoscopic structures starting from molecule passing to polymers and finally to supra molecular structures
Living systems are the result of a very precise and balanced hierarchical organisation of molecules. This means that from atomic to macroscopic scale, biological processes evolve via the organisation (and disorganisation) of matter. Molecules are often joined together via controlled-sequence polymerisation forming macromolecules with specific chemical signatures that direct supramolecular interaction between themselves and/or with water. Such interactions are singularly low in energy (i.e. few kTs), and their combination allows the formation of dynamic mesoscopic architectures with exquisite spatial and temporal control. This process, known as self-assembly, is ubiquitous in Nature and is at the core of many biological transformations. Alongside positional self-assembly, Nature creates energy gradients by enclosing chemicals into aqueous volumes using gated compartments. Both compartmentalisation and positional self-assembly create structures whose surfaces express several chemistries performing their function holistically, according to specific topological interactions. As our knowledge of this natural phenomenon advances, so do the efforts in creating functional materials and devices that exploit the same principles.
Among the different biomimetic efforts, we have focussed our attention in possibly one of the few that encompasses polymerisation, compartmentalisation and positional self-assembly in the same unit; Polymersomes. These are vesicles formed by the self-assembly of amphiphilic block copolymers in water. Copolymers can be fully synthetic and/or derived from biomolecules and their sequence can be engineered to control both interactions with water and among each other. In analogy to natural vesicles (typically formed by phospholipids), polymersomes can house controlled aqueous volumes to create chemical potentials across the membranes. However, the macromolecular nature of the polymersome building blocks allows the design of vesicle membranes with control over their thickness, brush density, mechanical properties, and permeability. Furthermore, copolymers can be designed with tunable solubility, and hence, polymersomes can be made responsive to a large plethora of environmental stimuli such as pH, ionic strength, enzymatic degradation, hydrolysis, light, temperature, and many others.
As shown in Fig. 1, we can summarise this into three steps process, at the molecular level (0.1-1nm) we can select appropriate molecules and use them as monomers for controlled polymerisation to form macromolecules with defined chemical signature to control supramolecular interactions (Macromolecular Engineering). These are then used to control the formation of larger structures (1-100nm) via a two-step processes (nucleation + growth) whose final topology is defined by the combination of the different supramolecular forces (Supramolecular Engineering). See below for further details:
Among the different biomimetic efforts, we have focussed our attention in possibly one of the few that encompasses polymerisation, compartmentalisation and positional self-assembly in the same unit; Polymersomes. These are vesicles formed by the self-assembly of amphiphilic block copolymers in water. Copolymers can be fully synthetic and/or derived from biomolecules and their sequence can be engineered to control both interactions with water and among each other. In analogy to natural vesicles (typically formed by phospholipids), polymersomes can house controlled aqueous volumes to create chemical potentials across the membranes. However, the macromolecular nature of the polymersome building blocks allows the design of vesicle membranes with control over their thickness, brush density, mechanical properties, and permeability. Furthermore, copolymers can be designed with tunable solubility, and hence, polymersomes can be made responsive to a large plethora of environmental stimuli such as pH, ionic strength, enzymatic degradation, hydrolysis, light, temperature, and many others.
As shown in Fig. 1, we can summarise this into three steps process, at the molecular level (0.1-1nm) we can select appropriate molecules and use them as monomers for controlled polymerisation to form macromolecules with defined chemical signature to control supramolecular interactions (Macromolecular Engineering). These are then used to control the formation of larger structures (1-100nm) via a two-step processes (nucleation + growth) whose final topology is defined by the combination of the different supramolecular forces (Supramolecular Engineering). See below for further details:
Macromolecular engineering |
SUpramolecular engineering |