The advances of supramolecular chemistry, bottom-up fabrication and bioinspired approaches have opened pathways to well-defined, hierarchical and functional materials at nanometer scale. Biological systems master the fabrication of near-perfect macromolecules and organized bulk materials from simple components under mild conditions. For self-assembly and material applications these biomaterials offer precision, diversity and functionality. This thesis demonstrates how biological and synthetic organic materials can be combined into bio-organic hybrid assemblies to promote biomedical and composite applications. In publication I multivalent, low-molecular-weight dendrons with cleavable disulfide bonds were synthesized and used for the electrostatic binding and triggered release of DNA. The dendrons bound DNA in a generation-dependent fashion and reduction of the disulfide bonds rapidly liberated the DNA. Degradable multivalent binding has been shown to enhance gene delivery, as the reducing cytosolic environment induces the release of DNA. In publication II the reducible dendrons were combined with photocleavable dendrons for the controlled formation of nanoscale DNA origamis. Binding of the origami constituents prevented their self-assembly into origamis, which was subsequently initiated by externally triggered degradation of the dendrons. Publication III studied the co-assembly of anionic icosahedral viruses and amphiphilic Janus dendrimers. Tuning of the dendrimer structures and the electrolyte concentration provided superlattices with a face-centered cubic unit cell. The assemblies resembled natural viral inclusion bodies, and provide means for studying their self-assembly processes. In publication IV rod-like cellulose nanocrystals (CNC) were grafted with a cationic polymer. The cationic CNCs efficiently assembled the anionic icosahedral viruses. Additionally, the CNCs enabled the concentration and extraction of the viruses from solution. The assemblies can be further transferred to biomedical applications and allow the recovery of viruses via electrolyte-gated release. In publication V the CNCs were functionalized with cross-linkable alkyl chains and used for the reinforcement of a synthetic rubber. The moisture-repellent composites showed a hierarchical structure, where the CNCs assembled into ordered biomimetic structures at high weight fractions. Simultaneously the stress-strain behavior abruptly changed from nonlinear rubbery to almost linear with increasing CNC fraction, while the tensile modulus increased by almost two orders of magnitude.
|Translated title of the contribution||Bio-orgaanisten hybridirakenteiden tutkimuksia|
|Publication status||Published - 2014|
|MoE publication type||G5 Doctoral dissertation (article)|
- biohybrid material
- cellulose nanocrystal