Molecular dynamics simulations of polyaminoamide (PAMAM) dendrimer aggregates: molecular shape, hydrogen bonds and local dynamics

Abstract

By means of Molecular Dynamic simulations we study over a wide range of temperature (200-400 K) the static and dynamics of polyaminoamide bulk dendrimers of third (16 end-groups) and fourth (32 end-groups) generations. The simulations show a very weak effect of the temperature on all the static properties analyzed (gyration radius, distribution of monomers, degree of dendrimer interpenetration) and, surprisingly, almost no interpenetration between dendrimers of the third generation. Unexpectedly, the propensity of forming inter-dendrimer hydrogen bonds is similar in both models but the intra-dendrimer hydrogen bonds turn out to be stronger in the fourth generation dendrimers than in the third generation ones. The terminal amine-groups are characterized by higher mobility if compared with the internal monomers. Finally, the detailed analysis of the local relaxation of the CH bonds shows that in the fourth generation dendrimers there is a decrease in the local dynamics moving from the inner toward the outer shells. This hierarchical behavior is not found in dendrimers of third generation.

How stable are amphiphilic dendrimers at the liquid–liquid interface?

“…33 As expected, the behaviour, and therefore applications, of rigid dendrimers such as polyphenylene ones is quite different compared with the flexible ones. 34 They for example do not show any backfolding of the arms (usually seen in all flexbile dendrimers) 35 leaving the central core of the molecules sterically accessible 36,37 and present a lower bulk density compared to the flexible one. 24 The interfacial properties of rigid dendrimers are also quite different than those of the flexible ones.…”

Nano Molecular‐Platform: A Protocol to Write Energy Transmission Program Inside a Molecule for Bio‐Inspired Supramolecular Engineering

“…Its four lobes divide energy nearly similarly, which leads to the formation of a PCM-sphere. However, the electrical fi eld induced transition induces a bipolar oscillation of PAMAM [ 16 ] at ≈ 300 K, bipolar means two PAMAM lobes get more energy than the other two, which causes the formation of a pairednanowire (Figure 1 a). Thus, the NR triggers MRs energetically that is the fi rst layer dynamics exactly as shown in Figure 4 e (note the electrostatic interaction shown in red and blue color).…”

“…The molecular simulation shows that the vibrational dynamics of four PAMAM lobes could generate fi ve local potential energy minima. [ 9,16 ] In which if two MRs from two neighboring PCMs come in contact, [ 16 ] then, due to natural rotation of these rotor molecules they could lock themselves, either via OCH 3 or by the coupling of upper plane into one unit. Notably, OCH 3 locking stops the associated band transitions (Figure 4 a).…”

Poly(amidoamine) dendrimer-mediated synthesis and stabilization of silver sulfonamide nanoparticles with increased antibacterial activity

“…The stronger electrostatic interaction between G4.0-PAMAM-NH 2 and G4.5-PAMAM-COOH dendrimers produced more stable particle size distributions. 19,22 AgSD NPs and effect of dendrimer coating on AgSD NP size AgSD NPs processed with microfluidization were more uniform in size distribution as the number of process cycles was increased. After three processing cycles, a unimodal size distribution was observed.…”