Poly(amidoamine) (PAMAM) dendrimers: from biomimicry to drug delivery and biomedical applications

Dendrimers in gene delivery.

Dendrimers have unique molecular architectures and properties that make them attractive materials for the development of nanomedicines. Key properties such as defined architecture and a high ratio of multivalent surface moieties to molecular volume also make these nanoscaled materials highly interesting for the development of synthetic (non-viral) vectors for therapeutic nucleic acids. Rational development of such vectors requires the link to be made between dendrimer structure and the morphology and physicochemistry of the respective nucleic acid complexes and, furthermore, to the biological performance of these systems at the cellular and systemic level. The review focuses on the current understanding of the role of dendrimers in those aspects of synthetic vector development. Dendrimer-based transfection agents have become routine tools for many molecular and cell biologists but therapeutic delivery of nucleic acids remains a challenge.

Supramolecular polymer networks are three-dimensional structures of crosslinked macromolecules connected by transient, non-covalent bonds; they are a fascinating class of soft materials, exhibiting properties such as stimuli-responsiveness, self-healing, and shape-memory. This critical review summarizes the current state of the art in the physical–chemical characterization of supramolecular networks and relates this knowledge to that about classical, covalently jointed and crosslinked networks. We present a separate focus on the formation, the structure, the dynamics, and the mechanics of both permanent chemical and transient supramolecular networks. Particular emphasis is placed on features such as the formation and the effect of network inhomogeneities, the manifestation of the crosslink relaxation dynamics in the macroscopic sample behavior, and the applicability of concepts developed for classical polymer melts, solutions, and networks such as the reptation model and the principle of time–temperature superposition (263 references).

Physical chemistry of supramolecular polymer networks

https://cyberleninka.org/article/n/1310744.pdf

Poly(amidoamine), polypropylenimine, and related dendrimers and dendrons possessing different 1 → 2 branching motifs : An overview of the divergent procedures

Photochemistry of nonconjugated bichromophoric systems. Intramolecular photocycloaddition of N,N'-alkylenedimaleimides in solution

The synthesis and characterization of a new series of polypropylenimine dendrimers is reported. Using a repetition of the sequence of a Michael addition to a primary amine, followed by a heterogeneously catalyzed hydrogenation, ultra-pure polypropylenimine macromolecules with molecular weights up to 6912 are synthesized. The reaction sequence allows the preparation of these dendrimers at very large scales, whilst the availability of a simple purification in the sequence affords ultra-pure samples. The polypropylenimine dendrimers are fully characterized; apart from the first 0.5 generation they are all oils, possess a Tg in the range from −90 to −40 °C, are unexpectedly stable, and their intrinsic viscosity drops after generation 4.

Large-scale production of polypropylenimine dendrimers

Kinetic scheme for intramolecular excimer formation in bis(.alpha.-naphthylmethyl)ether, involving different starting conformations

Reversible, supramolecular polymer networks based on commercially available bulk chemicals, and prepared using an industrially attractive route are described. The difunctional, low molecular weight polytetramethyleneoxide is functionalized with trimellitic imide, and reversibly crosslinked with the trifunctional melamine using the well known imide-diaminopyridine triple hydrogen bonding pattern. Molecular modelling calculations as well as experimental studies on model compounds indicate that the aimed 1:3 melamine - imide stoichiometry is obtained. The resulting reversible, supramolecular polymer structures show a rheological behaviour, that is typical for polymer networks. The results presented here describe an industrially accessible route to use supramolecular interactions in order to obtain materials with novel properties.

/pdf/novel-supramolecular-polymer-networks-based-on-melamine-and-2k9rwyo4xb.pdf

J. Put

Papers

Photochemistry of nonconjugated bichromophoric systems. Intramolecular photocycloaddition of N,N'-alkylenedimaleimides in solution

Large-scale production of polypropylenimine dendrimers

Kinetic scheme for intramolecular excimer formation in bis(.alpha.-naphthylmethyl)ether, involving different starting conformations

Novel Supramolecular Polymer Networks Based on Melamine- and Imide-Containing Oligomers

Occurrence of chain folding in micelles: A 13C NMR relaxation and photophysical study