Advances in the Elegance of Chemistry in Designing Dendrimers

Abstract

Highly functional and monodisperse macromolecules with tailored architecture constitute the key to designing efficient and smart nanomaterials. Dendrimers offer real potential to achieve this goal, and one of the earlier challenges faced by this novel class of polymers has been addressed by the evolution of synthetic methodologies. This review provides an evaluation of the role played by chemistry in taking these macromolecules of academic relevance to practical industrial and biological applications, in a relatively short period. One can now construct dendrimers in a 'made-to-order' fashion, for numerous applications in a variety of disciplines.

Enhancement of Cytotoxicity by Combining Pyrenyl-Dendrimers and Arene Ruthenium Metallacages

“…Interestingly, the four characteristic bands of the pyrenyl part found in the region 290−390 nm are much stronger in the encapsulated systems than in the spectra of the free pyrenyl derivatives. For example, the molar Chem3D simulations, 27 used to gain some structural information, show the dendritic arm extending from the metallaprism with the pyrenyl moiety being encapsulated inside the cavity (Figure 5) 6 were evaluated against human ovarian A2780 (cisplatin sensitive) and A2780cisR (acquired resistance to cisplatin) cancer cell lines. Their cytotoxicities, in comparison to cisplatin, are presented in Table 2.…”

“…The aromatic part of the pyrenyl-functionalized dendrimers may be encapsulated into the hydrophobic cavity of the hexanuclear a r e n e r u t h e n i u m m e t a l l a c a g e s [ R u 6 ( p -c y m ene) 6 (OO∩OO) 3 6+ ; tpt =2,4,6-tri(pyridin-4-yl)-1,3,5-triazine). 17 In contrast to the previously reported pyrenyl-dendrimers in metallaprism [1] 6+ , 16 the biological activity of both the dendrimers and of the host−guest systems has been evaluated.…”

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ABSTRACT: Three generations of pyrenyl bis-MPA dendrimers with two different end-groups, acetonide (pyr Gn )or alcohol (pyr Gn-OH )( n =1 −3), were synthesized, and the pyrenyl group of the dendritic molecules was encapsulated in the arene ruthenium metallacages, 6 (OO∩OO) 3 (tpt) 2 ] 6+ (OO∩OO = 5, [1] 6+ and 6,11-dioxydo-5,12-naphtacenedionato (dotq) [2] 6+ ; tpt =2,4,6-tri(pyridin-4-yl)-1,3,5-triazine). The host−guest properties of [guest⊂1] 6+ and [guest⊂2] 6+ were studied in solution by NMR and UV−vis spectroscopic methods, thus allowing the determination of the affinity constants.

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Dendrimers as anti-inflammatory agents

“…The two commonly used synthetic strategies for dendrimers include divergent and the convergent methods (Buhleier et al, 1978;Tomalia et al, 1984;Newkome et al, 1985;Tomalia et al, 1985;Hawker, Frechet, 1990;Hourani, Kakkar, 2010). The divergent method uses bottom-up approach where the synthesis of dendrimer is carried out beginning at the central core and moves towards the surface (Figure 1).…”

“…Recently, Tomalia and his group suggested that dendrimers themselves can exhibit anti-inflammatory properties mainly through inhibiting COX-2 activity (Chauhan et al, 2009). Kakkar's group recently showed that dendrimers synthesized using alkyne-azide "click" chemistry act as antiinflammatory agents (Castonguay et al, 2011;Hourani, Kakkar et al, 2010;Sharma et al, 2011a,b). Dendrimers with terminated acetylene (A) (DG0-A, DG1-A and DG2-A) and hydroxyl groups (OH) (DG1-OH) (Hourani et al, 2010) have shown to inhibit the LPS-induced nitric oxide (NO) and COX-2 (involved in prostaglandin (PGE2) synthesis in N9 microglia cells (resident immune cells of central nervous system).…”