Polyester and Ester Functionalized Dendrimers

Modular synthesis of self-assembling Janus-dendrimers and facile preparation of drug-loaded dendrimersomes

Materials and methods aimed at the next generation of nanoscale carriers for drugs and other therapeutics are currently in great demand. Yet, creating these precise molecular arrangements in a feasible and straightforward manner represents a remarkable challenge. Herein we report a modular synthetic route for amphiphilic Janus-dendrimers via a copper-catalyzed click reaction (CuAAC) and a facile procedure, using simple injection, to obtain highly uniform dendrimersomes with efficient loading of the model drug compound propranolol. The resulting assemblies were analyzed by dynamic light scattering and cryogenic transmission electron microscopy revealing the formation of unilamellar and multilamellar dendrimersomes. The formation of a bilayer structure was confirmed using cryo-TEM and confocal microscopy visualization of an encapsulated solvatochromic dye (Nile Red). The dendrimersomes reported here are tunable in size, stable over time and display robust thermal stability in aqueous media. Our results expand the scope of dendrimer-based supramolecular colloidal systems and offer the means for one-step fabrication of drug-loaded dendrimersomes in the size range of 90-200 nm, ideal for biomedical applications.

Multiple antigenic peptide (MAP): a synthetic peptide dendrimer for diagnostic, antiviral and vaccine strategies for emerging and re-emerging viral diseases

The peptide dendrimer provides novel strategies for various biological applications. Assembling of peptide in macromolecular structure is expected to give rational models as drugs, their delivery and diagnostic reagents. Improved understanding of virus structure and their molecular interactions with ligands have paved the way for treatment and control of emerging and re-emerging viral diseases. This review presents a brief account of a synthetic peptide dendrimer used for diagnostic, therapeutic and prophylactic applications. The designs comprise of multiple antigenic peptides which are being used as alternate synthetic antigens for different viruses.

3,4-Dimeth-oxy-4'-methyl-biphen-yl

In the title compound, C₁₅H₁₆O₂, the dihedral angle between the planes of the aromatic rings is 30.5 (2)°. In the crystal, mol­ecules are linked via C—H⋯O hydrogen bonds and C—H⋯π inter­actions, forming a two-dimensional network lying parallel to (100).

3,5-Dimeth-oxy-4'-methyl-biphen-yl

The title compound, C₁₅H₁₆O₂, crystallizes with three independent mol­ecules in the asymmetric unit. The intra­molecular torsion angle between the aromatic rings of each mol­ecule are −36.4 (3), 41.3 (3) and −37.8 (3)°. In the crystal, the complicated packing of the mol­ecules forms wave-like layers along the b and c axes. The mol­ecules are connected via extensive meth­oxy–phenyl C—H⋯π inter­actions. A weak C—H⋯O hydrogen-bonding network also exists between meth­oxy O atoms and aromatic or meth­oxy H atoms.

Dendrimer/methyl methacrylate co-polymers: residual methyl methacrylate and degree of conversion

Dendrimer/methyl methacrylate co-polymers were studied for use in dental composites. The aim was to determine the effects of methyl methacrylate concentration in the resin mixture and polymerization method on the degree of conversion and residual monomer content of the copolymers. Two dendrimers were studied, D12 with 12 reactive methacrylate groups and D24 with 24 reactive groups. The concentration of methyl methacrylate varied from 20 wt% to 50 wt% of monomers. Camphorquinone (CQ) was used as the light-activation initiator and 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) as the activator, both in the quantity of 3.0 wt%. Three polymerization methods were used: photo-polymerization, photo-polymerized immediately followed by post-polymerization at 120 degrees C for 15 min, and photo-polymerization followed by postpolymerization after 7 days. The degree of conversion was determined using FT-IR. Residual monomers were extracted with tetrahydrofuran and methanol and analyzed with HPLC. The highest degrees of conversion were 65 and 62%, and the lowest residual monomer contents 1.0 and 1.5% for D12 and D24, respectively. These were measured after heat-induced post-polymerization. For D12, increasing the proportion of methyl methacrylate decreased the degree of conversion and increased the residual monomer content after photo-polymerization. Post-polymerization enhanced the polymerization of the dendrimer co-polymers in respect of degree of conversion and residual monomer content. The present study suggested that the tested dendrimer/methyl methacrylate copolymers require heat-induced polymerization to reach the generally accepted levels of degree of conversion and residual monomers.

Supramolecular Self-Organization of “Janus-like” Diblock Codendrimers: Synthesis, Thermal Behavior, and Phase Structure Modeling

We report on the design and synthesis of three series of segmented amphiphilic block codendrimers, and on their self-organizing behavior in liquid-crystalline mesophases. Connecting two prefunctionalized monodendrons, each differing in their chemical constitution and generation number, yielded these diblock supermolecules. One wedge of the codendrimer was made hydrophobic, and is based on a branched poly(benzyl ether) monodendron functionalized at the periphery by lipophilic aliphatic fragments (also known as Percec dendrons). The other segment was made hydrophilic by the grafting of hydroxyl-containing moieties onto the focal functions of the former dendrons. Both types of dendrons were prepared independently by convergent methods and then joined in the ultimate stage of the synthetic procedure by cross-coupling reactions. In this way, the proportion of the dendritic blocks was varied independently to allow control of the hydrophilic/hydrophobic balance (HHB), the hydrogen-bonding ability, and consequently the capacity to tune the mesomorphic properties of the resulting "superamphiphiles" was anticipated. Essentially all the dendritic compounds display a thermotropic mesomorphism directly at or near room temperature as determined by using X-ray diffraction, polarized optical microscopy, and differential scanning calorimetry. The nature and the supramolecular organization of the mesophases, namely columnar and cubic phases, are correlated to the size of the respective block monodendrons and the chemical structures of the dendromesogens. The molecular organization within the cubic phases can be geometrically described and well understood by the space-filling polyhedron model.

Peptide dendrimers

Dendrimers are branched structures and represent a fast growing field covering many areas of chemistry. Various types of dendrimers differing in composition and structure are mentioned, together with their practical use spanning from catalysis, transport vehicles to synthetic vaccines. The main stress is given to peptide dendrimers, namely, multiple antigenic peptides (MAPs). Their synthesis, physicochemical properties, biological activities, etc. have been described with many examples. MAPs can be used as diagnostics, mimetics, for complexation of different cations, as vaccines against parasites, bacteria, viruses, etc.

Polyesters based on diacid monomers

Polymers with ester linkages in their main chain comprise a family of polymers with immense diversity and versatility. This review deals with the preparation of such polymers from dicarboxylic acid monomers, and the result in terms of properties and applicability. Polyesters alone, and their copolymers with amides, anhydrides, urethanes, imides, ethers or other functional groups, offer countless opportunities to tune the properties of the resulting material within a broad range. Of particular interest is the inherent biodegradability of the ester linkage. Biodegradability is sought after in a wide range of applications, above all in the preparation of environmentally friendly polymers and biomedical materials for temporary surgical use and in drug delivery.