Poly Propyleneamine Dendrimers Research Articles

Retraction Note: Application of Polypropylene Amine Dendrimers (POPAM)-Grafted MWCNTs Hybrid Materials as a New Sorbent for Solid-Phase Extraction and Trace Determination of Gold(III) and Palladium(II) in Food and Environmental Samples

Retraction Note: Application of Polypropylene Amine Dendrimers (POPAM)-Grafted MWCNTs Hybrid Materials as a New Sorbent for Solid-Phase Extraction and Trace Determination of Gold(III) and Palladium(II) in Food and Environmental Samples

Synthesis and photophysical characterisation of 3-bromo-4-dimethylamino-1,8-naphthalimides and their evaluation as agents for antibacterial photodynamic therapy

Through the peripheral modification of a first-generation polypropylene amine dendrimer two new photoactive dendrimers containing 4-dimethylamino-1,8-naphthalimide (3) and 3-bromo-4-dimethylamino-1,8-naphthalimide (4), have been obtained. Photophysical and spectral characteristics of these dendrimers were investigated in two organic solvents. We found that they absorb light in the visible spectral region and emit yellow-green fluorescence. Antimicrobial activity of dendrimers against pathogenic microorganisms has been investigated in solution and after deposition on a cotton fabric. For the first time, 1,8-naphthalimide derivatives have been tested as active components in antibacterial photodynamic therapy. To clarify the dendrimer effect, the results obtained were compared with those from two monomeric 1,8-naphthalimides (1 and 2) containing the same substitutes in the chromophore system. Cytotoxicity and antiviral activity of the dendrimers were also assessed.

Synthesis and spectral characterization of a new PPA dendrimer modified with 4-bromo-1,8-naphthalimide and in vitro antimicrobial activity of its Cu(II) and Zn(II) metal complexes

This article describes the peripheral modification of a polypropylene amine dendrimer of second generation with eight 4-bromo-1,8-naphthalimide units and its copper and zinc complexes. The new dendrimer and its metal complexes have been characterized by electronic (UV–vis and fluorescence) and vibrational (IR and Raman) spectral methods in view of their antibacterial and antifungal activity. The results have shown that the two metal ions form complexes with the dendrimer ligand. In vitro antimicrobial screening of the newly synthesized metallodendrimers showed promising antimicrobial activities against some pathogenic Gram-positive and Gram-negative bacteria and the yeasts Candida lipolytica. The results suggest that the new metal complexes could find application in designing new antimicrobial preparations to control the spread of infections caused especially by Acinetobacter, Micrococcus and Candida species.

Multivalency in the Gas Phase: H/D Exchange Reactions Unravel the Dynamic “Rock ’n’ Roll” Motion in Dendrimer-Dendrimer Complexes

Noncovalent dendrimer-dendrimer complexes were successfully ionized by electrospray ionization of partly protonated amino-terminated polypropylene amine (POPAM) and POPAM dendrimers fully functionalized with benzo[21]crown-7 on all branches. Hydrogen/deuterium exchange (HDX) experiments conducted on dendrimer-dendrimer complexes in the high vacuum of a mass spectrometer give rise to a complete exchange of all labile NH hydrogen atoms. As crown ethers represent noncovalent protective groups against HDX reactions on the ammonium group to which they are coordinated, this result provides evidence for a very dynamic binding situation: each crown is mobile enough to move from one ammonium binding site to another. Schematically, one might compare this motion with two rock 'n' roll dancers that swirl around each other without completely losing all contact at any time. Although the multivalent attachment certainly increases the overall affinity, the "microdynamics" of individual site binding and dissociation remains fast.

RETRACTED ARTICLE: Application of Polypropylene Amine Dendrimers (POPAM)-Grafted MWCNTs Hybrid Materials as a New Sorbent for Solid-Phase Extraction and Trace Determination of Gold(III) and Palladium(II) in Food and Environmental Samples

A new method which utilizes a polypropylene amine dendrimers (POPAM)-grafted multi-walled carbon nanotubes (MWCNTs) hybrid materials as an effective sorbent in solid-phase extraction has been developed for separation and preconcentration of Au(III) and Pd(II) trace levels in food, water and soil samples. The optimum experimental conditions such as pH, flow rates, type, concentration, and volume of the eluent for elution of gold and palladium ions, breakthrough volume, and effect of potentially interfering ions on separation and determination of these noble metals were investigated. The extraction recoveries for the mentioned noble metals were greater than 98 % and the limits of detection were 0.08 and 0.12 ng mL−1 for gold and palladium, respectively. The relative standard deviations of the method were less than 4 % for eight separate column experiments for determination of 5.0 μg of gold and palladium ions. The adsorption capacity of the modified MWCNT was 92 mg g−1 for gold and 74 mg g−1 for palladium on POPAM-grafted MWCNTs. Validation of the suggested method was performed by analyzing certified reference materials. Finally, the proposed method was applied for determination of gold(III) and palladium(II) in real samples, including fish, shrimp, water, and soil.

Ultrafast energy transfer in dansylated POPAM–eosin complexes

Excitation energy transfer (EET) in dendritic host–guest complexes has been studied. Three generations G2, G3 and G4 of dansyl substituted poly(propyleneamine) dendrimers (POPAM) were complexed with a fluorescent dye eosin in chloroform solution. Arrival of excitation from dansyls to eosin was monitored by femtosecond transient absorption spectroscopy. EET rates from the dansyls to eosin(s) are characterised by two time constants 1 ps and 6 ps independent of dendrimer generation. Relaxation processes in eosin were clearly faster when complexed with dendrimer than in solution. As several eosins are bound to G3 and G4 dendrimers, besides host–guest interaction, also eosin–eosin interactions may contribute to the faster relaxation observed in these complexes.

Surface Grafting Polyethylene Glycol (PEG) onto Poly(ethylene-co-acrylic acid) Films

Two reaction schemes were developed to covalently graft poly(ethylene glycol) (PEG) chains on poly(ethylene-co-acrylic acid) (EAA) surfaces. The schemes involved surface grafting of linker molecules L-lysine or polypropyleneamine dendrimer (AM64), with subsequent covalent bonding of PEG chains to the linker molecules. NHS and EDC were used to activate the carboxylic acid groups of the EAA in the outermost region of the film, estimated to be 20 nm by ATR-FTIR spectroscopy. XPS demonstrated that the conversion of this activation step was almost 100% in the detected region. After activation, L-lysine or dendrimer was grafted onto the EAA surface, followed by PEG grafting. Combining the data from ATR-FTIR, XPS, and contact angle goniometry, it was found that the PEG chains were grafted on the surface of the EAA film and larger surface coverage was achieved when the dendrimer was used as the intermediate layer. This surface also had the lowest water contact angle.

Simulation of some dynamical aspects of the photophysics of dye molecules encapsulated in a dendrimer

We use a combination of molecular dynamics and quantum chemical calculations to investigate the photophysics of Eosin Y encapsulated in a fourth generation of poly-propylene amine dendrimer functionalized in the periphery with dansyl units. Once in contact with the macromolecule, the guests display a double exponential decay of the excited states that is reproduced by the present model.