Propylene Imine Dendrimers Research Articles

Targeting potential and anti-HIV activity of lamivudine loaded mannosylated poly (propyleneimine) dendrimer

T-lymphocytes, dendritic cells and macrophages are the target cells for HIV. The infected macrophages are considered as reservoirs for spreading the virus . Treatment of HIV infection therefore must reach these cells in addition to the organs like brain, liver and bone marrow. Lectin receptors, which act as molecular targets for sugar molecules, are found on the surface of these cells of the phagocytic system. The purpose of the present study is to investigate the targeting potential and anti HIV activity of lamivudine (3TC) loaded mannosylated fifth generation Poly (propyleneimine) dendrimers (MPPI). The entrapment efficiency of 3TC loaded MPPI and 5th generation poly(propyleneimine) dendrimer (PPI) were found to be 43.27 ± 0.13% and 35.69 ± 0.2% respectively. The in vitro drug release profile shows that while PPI releases the drug by 24 h, the MPPI slows down and hence prolongs the release up to 144 h (96.89 ± 1.8% in case of MPPI). The results of in vitro ligand agglutination assay indicated that even after conjugation with PPI, mannose displayed binding specificity towards Con A. The subtoxic concentrations of free 3TC, blank PPI, blank MPPI, drug loaded PPI and drug loaded MPPI, determined on MT2 cells, were found to be 0.625, 0.039, 0.156, 0.039 and 0.156 nM/ml respectively. Significant increase in cellular uptake of 3TC was observed when MPPI was used, which was 21 and 8.3 times higher than that of free drug ( p < 0.001) and PPI ( p < 0.001) at 48 h respectively. Antiretroviral activity was determined using MT2 cell lines by estimating p24 antigen by ELISA. 3TC loaded PPI and MPPI formulations were found to possess higher anti-HIV activity at a concentration as low as 0.019 nM/ml, as compared to that of free drug, which was found to be extremely significant ( p < 0.001). The significantly higher anti-HIV activity of PPI and MPPI is due to the enhanced cellular uptake of 3TC in formulation as compared to that of free drug Results suggest that the proposed carrier hold potential to increase the efficacy and reduce the toxicity of antiretroviral therapy.

End-on and Side-on Nematic Liquid Crystal Dendrimers

A group of nematic materials based on poly(propyleneimine) dendrimers (PPI) containing two types of mesogenic subunits were synthesized. The presence of different types of mesogenic group, the topology of the attachment to the core (end-on and side-on), and the chemical nature of the linking connection to the PPI scaffold (imine or amide) were used to tailor the mesomorphic properties. The materials were characterized by a variety of techniques including 1H, 13C NMR spectroscopy, GPC, MALDI−TOF MS, DSC, POM, and X-ray diffraction. The crystalline state, when it exists, was found to be suppressed for most of the materials once they had undergone the first transition to the isotropic phase. The majority of the compounds exhibited glass transitions near to or lower than room temperature and an accompanying wide temperature range mesophase. All of the side-on dendrimers synthesized exhibit a nematic mesophase whereas end-on dendrimers exhibit different mesophases depending on the length of the terminal chain ...

Morphological change of gold–dendrimer nanocomposites by laser irradiation

Gold–dendrimer nanocomposites are prepared in aqueous solutions in the presence of poly(amidoamine)dendrimers (PAMAM) (generation 3 and 5) or poly(propyleneimine)dendrimers (PPI) (generation 3 and 4) by wet chemical NaBH 4 method. Thus prepared gold–dendrimer nanocomposites are irradiated by laser at 532 nm. UV–vis absorption spectroscopy and transmission electron microscopy reveal that the gold nanoparticles grow with the laser irradiation time as well as the fluence of the laser; in particular, the gold nanoparticles prepared at lower concentrations of PAMAM dendrimer as well as lower generations of PAMAM grow significantly. On the other hand, in the case of PPI dendrimers, the gold nanoparticles hardly grow by irradiation. In addition, dynamic light-scattering measurements show that the laser irradiation markedly promotes the association of the gold–PAMAM G3 dendrimer nanocomposites compared to that of the gold–PAMAM G5 dendrimer nanocomposites, while the sizes of association for the gold–PPI G3, G4 dendrimer nanocomposites hardly change by laser irradiation.

UV照射による金-ポリプロピレンイミンデンドリマーナノコンポジットの調製

表面アミノ基を有するポリプロピレンイミンデンドリマー (PPI) (世代2, 3または4) の存在下, UV照射により金ナノ粒子を調製した。紫外可視吸収スペクトル, 動的光散乱法ならびに透過型電子顕微鏡を用いて金-PPIナノコンポジットの生成ならびに構造をしらべた。金イオンの還元はUV照射時間の増加にともない進み, また得られた金ナノ粒子の平均粒子径はデンドリマーの濃度が増えると増加した。金-PPIナノコンポジットの構造はPPI分子が金ナノ粒子に吸着することにより形成されることが示唆された。さらに, 金-PPIナノコンポジットによる4-ニトロフェノールの還元反応における反応定数はPPIデンドリマーの世代ならびに濃度に関係なくほぼ同じであることがわかった。

Comparison of PAMAM–Au and PPI–Au Nanocomposites and Their Catalytic Activity for Reduction of 4-Nitrophenol

Dendrimer–Au nanocomposites are prepared in aqueous solutions using poly(amidoammine)dendrimers (PAMAM) (generation 2, 3, and 5) and poly(propyleneimine)dendrimers (PPI)(generation 2, 3, and 4) by wet chemical NaBH 4 method. The Au nanoparticles thus obtained are 2–4 nm in diameter for both dendrimers and no generation dependence on the particle size is observed, whereas the generations of the dendrimers are increased as stabilization of Au–nanoparticles is achieved with lower dendrimer concentrations. Studies of the reduction reaction of 4-nitrophenol using these nanocomposites show that the rate constants for the PAMAM dendrimers (generations 2 and 3) are higher than those for the PPI dendrimers (generations 2 and 3), while a distinct difference in the rate constants is not seen for the PAMAM dendrimer (generation 5) or the PPI dendrimer (generation 4). In addition, the rate constants for the reduction of 4-nitrophenol involving all the dendrimers decrease with increases in dendrimer concentrations.