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A stable and sensitive electrochemiluminescence (ECL) detection protocol of o-aminophenol was developed, which was based on CdSe quantum dots (QDs) and the cavity structure of β-cyclodextrin. In this experiment, the working electrode was prepared by PAMAM and CdSe QD and β-cyclodextrin using layer self-assembly method under the infrared lamp. Under the optimum conditions, a good linear relationship with the concentration of o-aminophenol from 1.0 × 10-7 mol·L-1 to 8.0 × 10-6 mol·L-1 and the detection limits as low as 2.3 × 10-8 mol·L-1 (3σ) were achieved. Good selectivity and repeatability are advantages of the sensor which is feasible. [ABSTRACT FROM AUTHOR]

An ultrasensitive gene specific DNA sensor was developed by covalent immobilization of single stranded (ssDNA) probe on Au/PAMAM nanohybrid modified electrode for early detection of pathogen Streptococcus pyogenes infection in human. An electrochemical response was measured after hybridization with single stranded genomic DNA (ssG-DNA) of S. pyogenes from the patient samples. The nanohybrid sensor was characterized by FTIR, SEM and validated with patient real samples. The sensitivity of the sensor was 860.95 (μA/cm 2 )/ng DNA and lower limit of detection was 150 fg in 6 μL samples. The sensor is highly specific and can save damage of human mitral and aortic heart valves at early stage of infection by rapid diagnosis (30 min) and medical care. [ABSTRACT FROM AUTHOR]

In recent years, functional nanomaterials have found an appreciable place in the understanding and treatment of cancer. This work demonstrates the fabrication and characterization of a new class of cationic, biocompatible, peptide dendrimers, which were then used for stabilizing and functionalizing magnetite nanoparticles for combinatorial therapy of cancer. The synthesized peptide dendrimers have an edge over the widely used PAMAM dendrimers due to better biocompatibility and negligible cytotoxicity of their degradation products. The surface engineering efficacy of the peptide dendrimers and their potential use as drug carriers were compared with their PAMAM counterparts. The peptide dendrimer was found to be as efficient as PAMAM dendrimers in its drug-carrying capacity, while its drug release profiles substantially exceeded those of PAMAM’s. A dose-dependent study was carried out to assess their half maximal inhibitory concentration (IC 50 ) in vitro with various cancer cell lines. A cervical cancer cell line that was incubated with these dendritic nanoparticles was exposed to alternating current magnetic field (ACMF) to investigate the effect of elevated temperatures on the live cell population. The DOX-loaded formulations, in combination with the ACMF, were also assessed for their synergistic effects on the cancer cells for combinatorial therapy. The results established the peptide dendrimer as an efficient alternative to PAMAM, which can be used successfully in biomedical applications. [ABSTRACT FROM AUTHOR]

A novel chelating resin obtained via growth of PAMAM dendron on surface of styrene divinyl benzene resin beads, followed by diglycolamic acid functionalization of the dendrimer terminal. Batch experiments were conducted to study the effects of pH, nitric acid concentration, amount of adsorbent, shaking time, initial metal ion concentration and temperature on U(VI) and Th(IV) adsorption efficiency. Diglycolamic acid terminated PAMAM dendrimer functionalized styrene divinylbenzene chelating resin (DGA-PAMAM-SDB) is found to be an efficient candidate for the removal of U(VI) and Th(IV) ions from aqueous (pH > 4) and nitric acid media (> 3 M). The sorption equilibrium could be reached within 60 min, and the experimental data fits with pseudo-second-order model. Langmuir sorption isotherm model correlates well with sorption equilibrium data. The maximum U(VI) and Th(IV) sorption capacity onto DGA-PAMAMG 5 -SDB was estimated to be about 682 and 544.2 mg g −1 respectively at 25 °C. The interaction of actinides and chelating resin is reversible and hence, the resin can be regenerated and reused. DFT calculation on the interaction of U(VI) and Th(IV) ions with chelating resin validates the experimental findings. [ABSTRACT FROM AUTHOR]

Purpose: To develop peptide-dendrimer-paclitaxel conjugates for the treatment of heterogeneous stage 1 non small cell lung cancer (NSCLC) in 293T and L132cell line. Method: Dendrimer-paclitaxel conjugates (PAMAM-PTX) were prepared by NHS method and the conjugates were used for the synthesis of peptide-dendrimer-paclitaxel conjugates (GE-PAMAM-PTX). The particle sizes of PAMAM-PTX and GE-PAMAM-PTX were measured. Entrapment efficiency of PTX in PAMAM-PTX was measured while GE-PAMAM-PTX. PTX release from PAMAM-PTX and GEPAMAM- PTX was determined using a dialysis bag in pH 7.4 phosphate buffer. The cytotoxicity of PAMAM-PTX, GE-PAMAM-PTX, PAMAM and PTX was evaluated by 3-(4,5-dimethylthiazol-2-Yl)-2,5- diphenyltetrazolium bromide (MTT) assay using 293T cell lines. In vitro cellular uptake assay of PAMAM-PTX and GE-PAMAM-PTX and PTX at concentrations ranging from 0.01 to 0.5μM for 8 h was carried out in NSCLC cell lines 293T and L132. Results: More than 95 % entrapment efficiency of GE-PAMAM-PTX was observed with loading efficiency of 25 %. GE-PAMAM-PTX conjugates showed sustained release of PTX (~85 %) towards the end of 50 h. GE-PAMAM-PTX conjugates were more cytotoxic than pure PTX and PAMAM-PTX conjugates. The remarkable uptake of GE-PAMAM-PTX appear to be due to receptor-mediated endocytosis in the cell lines. The presence of ligand (GE) on PAMAM-PTX surface enabled the complex to bind to the over-expressed receptors on the cell lines. Conclusion: GE-PAMAM-PTX can facilitate targeting of paclitaxel to lung cancer cell lines and tumors and facilitate release of the drugs in a sustained manner to improve the therapeutic efficacy of PTX. [ABSTRACT FROM AUTHOR]

In the current study camptothecin-loaded pegylated PAMAM dendrimer were synthesized and were functionalized with AS1411 anti-nucleolin aptamers for site-specific targeting against colorectal cancer cells which over expresses nucleolin receptors. The morphological properties and size dispersity of the prepared nanoparticles were evaluated using transmission electron microscope (TEM) and DLS. The drug-loading content and encapsulation efficiency were obtained 8.1% and 93.67% respectively. The in vitro release of camptothecin from the formulation was provided the sustained release of encapsulated camptothecin during 4 days. Comparative in vitro cytotoxicity experiments demonstrated that the targeted camptothecin loaded-pegylated dendrimers had higher antiproliferation activity, towards nucleolin-positive HT29 and C26 colorectal cancer cells than nucleolin-negative CHO cell line. Fluorscence microscopy and flow cytometry also confirmed the enhanced cellular uptake of AS1411 targeted pegylated-dendrimer. In vivo study in C26 tumor-bearing BALB/C mice revealed that the AS1411-functionalized camptothecin loaded pegylated dendrimers improved antitumor activity and survival rate of the encapsulated camptothecin. Conjugation of AS1411 aptamer to the camptothecin loaded-pegylated dendrimer surface provides site-specific delivery of camptothecin, inhibit C26 tumor growth in vivo and significantly decrease systemic toxicity. These results suggested that the new nucleolin-targeted pegylated PAMAM dendrimer as a delivery system for camptothecin have the potential for the treatment of nucleolin-overexpressed colorectal cancer. [ABSTRACT FROM AUTHOR]

Bortezomib (BTZ) is the first proteasome inhibitor approved by the US-FDA is majorly used for the treatment of newly diagnosed and relapsed multiple myeloma including mantle cell lymphoma. BTZ is hydrophobic in nature and is a major cause for its minimal presence as marketed formulations. The present study reports the design, development and characterization of dendrimer based formulation for the improved solubility and effectivity of bortezomib. The study also equally focuses on the mechanistic elucidation of solubilization by two types of dendrimers i.e. fourth generation of poly (amidoamine) dendrimers (G4-PAMAM-NH 2 ) and fifth generation of poly (propylene) imine dendrimers (G5-PPI-NH 2 ). It was observed that aqueous solubility of BTZ was concentration and pH dependent. At 2 mM G5-PPI-NH 2 concentration, the fold increase in bortezomib solubility was 1152.63 times in water, while approximately 3426.69 folds increase in solubility was observed at pH 10.0, respectively ( p < 0.05). The solubility of the drug was increased to a greater extent with G5-PPI-NH 2 dendrimers because it has more hydrophobic interior than G4-PAMAM-NH 2 dendrimers. The release of BTZ from G5-PPI-NH 2 complex was comparatively slower than G4-PAMAM-NH 2 . The thermodynamic treatment of data proved that dendrimer drug complexes were stable at all pH with values of ΔG always negative. The experimental findings were also proven by molecular simulation studies and by calculating RMSD and intermolecular hydrogen bonding through Schrodinger software. It was concluded that PPI dendrimers were able to solubilize the drug more effectively than PAMAM dendrimers through electrostatic interactions. [ABSTRACT FROM AUTHOR]

Dendritic-linear surfactants 1G PAMAM-Si and 2G PAMAM-Si were prepared by grafting the single epoxy terminated polydimethylsiloxane (SEPDMS) onto the 1G and 2G dendritic polyamide-amine (PAMAM), respectively. SEPDMS was synthesized by hydrogen-terminated polydimethylsiloxane and allyl glycidyl ether in chloroplatinic acid. The optimum grafting conditions were obtained by single-factor experiments when the mole ratio of SEPDMS and PAMAM was 0.95:1, the reaction temperature was 60 °C, the reaction time was 5 h and the solvent percentage was 60%. The molecular structure of PAMAM-Si was characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, gel permeation chromatograph and potentiometric acid-base titration. Furthermore, the stability, surface activity and emulsifying ability of the prepared surfactants were studied. The results showed that PAMAM-Si has high stability against dilution, acids, alkalies and salts. PAMAM-Si surfactants can significantly reduce the surface tension of water. And 2G PAMAM-Si is superior to 1G PAMAM-Si at the ability of emulsifying oil. [ABSTRACT FROM AUTHOR]

An impedimetric mga gene specific DNA sensor was developed by immobilization of single stranded DNA probe onto the screen printed modified gold-dendrimer nanohybrid composite electrode for early and rapid detection of S. pyogenes in human throat swab samples causing rheumatic heart disease. Electrochemical impedance response was measured after hybridization with bacterial single stranded genomic DNA (ssG-DNA) with probe. The sensor was found highly specific to S. pyogenes and can detect as low as 0.01 ng ssDNA in 6 µL sample only in 30 min. The nanohybrid sensor was also tested with non-specific pathogens and characterized by FTIR. An early detection of the pathogen S. pyogenes in human can save damage of mitral and aortic heart valves (rheumatic heart disease) by proper medical care. [ABSTRACT FROM AUTHOR]

Microbiological quality of drinking water is an important aspect of water quality. The aim of this research work was to fabricate and modify G2 and G4 dendrimers as novel antibacterial agent for local application. Poly(amidoamine) (PAMAM) (G2 and G4) dendrimers were fabricated and modified into quaternary ammonium salts using halogens groups (Cl, Br, I), and characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), and dynamic light scattering (DLS) analysis. The results of these analysis proved that nanostructure dendrimer and their quaternary ammonium salts are well fabricated. For evaluation of the antimicrobial property, the water samples were collected from rural drinking water resources, and the bacteria isolated and identified from these samples were Escherichia coli, Klebsiella oxytoca, Bacillus subtilis, and Staphylococcus aureus. The antimicrobial activities of PAMAM dendrimers (G2 and G4) and modified PAMAM dendrimers (G2 Cl, G2 Br, G2 I, G4 Cl, G4 Br, and G4 I) against gram-positive and gram-negative bacteria were examined by calculating minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and disc diffusion methods. Quaternary ammonium salts exhibited more antimicrobial efficacy against bacteria compared with unmodified ones. The most antibacterial effect was obtained by G4 I with MIC: 52, 50, 55, and 57 µg/ml, and MBC: 64, 67, 71, and 75 µg/ml for Staphylococcus aureus, Bacillus subtilis, Klebsiella oxytoca, and Escherichia coli, respectively. The disc diffusion test of G4 I (60 µM) on different bacteria showed inhibition zone diameters of 31, 28, 26, and 25 ml for Staphylococcus aureus, Bacillus subtilis, Klebsiella oxytoca, and Escherichia coli, respectively. [ABSTRACT FROM AUTHOR]

Resveratrol (RSV) is well known for its anti-oxidant and anti-aging properties. However, resveratrol is insoluble in water and has stability issues. Recently, efforts were placed to prepare a resveratrol-based advanced anti-aging topical product but it contains harsh organic solvents and oils that could be harmful to the human body and the environment. Hence, we propose the use of a multifunctional dendrimer to solve the solubility and stability issues of resveratrol. A dendrimer-resveratrol complex was prepared, optimized and tested for solubility enhancement, stability in solution and cream dosage forms. We have also developed a high performance liquid chromatography method to measure the resveratrol within the final product. PAMAM dendrimers increased the solubility and stability of resveratrol in water and semisolid dosage forms. Therefore, this product would be water based ‘green’ formulation devoid of harsh organic solvents and oils and can be safely applied to the skin. Additionally, we have shown that the dendrimer helped to increase overall RSV loading and skin penetration of resveratrol. The dendrimer-RSV formulation was successfully scaled up towards commercialization. Dendrimer with RSV has led to an innovation in anti-aging cream and solutions that could be commercially marketed. Dendrimer-RSV complex could also be added to other product forms for additional purposes and applications. [ABSTRACT FROM AUTHOR]

Purpose: A bifunctional RGDTAT peptide-modified PEG-PAMAM dendrimer conjugate RGDTAT-PEG-PAMAM (RTPP) was established for the targeted treatment of αvβ3-overexpressing tumor cells. Methods: The RGDTAT peptide was synthesized and attached to PAMAM using PEG to construct the RTPP conjugate. The methotrexate (MTX) encapsulated RTPPM complex was prepared and characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM) and in vitro release. The targeting ability was then studied in cells and tumor-bearing nude mice using fluorescence microscopy, confocal fluorescence microscopy, flow cytometry, and in vivo imaging. The cytotoxicity and pharmacokinetics of the RTPPM complex was also evaluated in cells and rats. Results: The successful synthesis of the RTPP conjugate was confirmed by H-NMR. DLS and TEM measurements revealed that the size was 37 nm and the complex had a spherical shape. RTPP and RTPPM were taken up by αvβ3-overexpressing cells more efficiently than by αvβ3-lowexpressing cells. The RTPP conjugate localized to the cell nucleus and accumulated in the tumor more efficiently than did the conjugates without RGDTAT. The pharmacokinetic study of the RTPPM complex showed sustained drug release. Conclusions: The bifunctional peptide-mediated dendrimer-based RTPP conjugate can serve as a promising nanocarrier for targeted drug delivery to improve anti-tumor activity. [ABSTRACT FROM AUTHOR]

Chemotherapy, a conventional method assessed in recent oncology studies, poses numerous problems in the clinical environment. To overcome the problems inherent in chemotherapy, an intelligent drug delivery system has come to the forefront of cancer therapeutics. In this study, we designed a dendrimer-based pharmaceutical system together with a single-stranded AS1411 aptamer ( APTAS1411) as a therapeutic strategy. The polyamidoamine ( PAMAM)-polyethylene glycol ( PEG) complex was then conjugated with the AS1411 aptamer and confirmed by atomic-force microscopy ( AFM) and Fourier transform infrared spectroscopy ( FTIR) .In this study, we show that the conjugated PAMAM- PEG- APTAS1411complex dramatically increased PAMAM- PEG-5- FU uptake by MKN45 gastric cancer cells. We also demonstrated both the stability of the nanoparticle-5- FU- APTAS1411 complex, by thin layer chromatography ( TLC), and an increase in 5-fluorouracil (5- FU) accumulation in the vicinity of cancerous tumors. This smart drug delivery system is capable of effectively transferring 5- FU to MKN45 gastric cancer cells in consistent and without toxic effects. [ABSTRACT FROM AUTHOR]

Membrane based wastewater treatment technologies in which polymeric membranes are most commonly used have been extensively applied in water/wastewater treatment to help address the issue of water shortage through water/wastewater reclamation and reuse. However, polymeric membranes due to their hydrophobic nature are subject damage caused by accumulation of organic/inorganic fouling during filtration processes, which results in a number of issues such as low water flux and low pollutant rejection. Several strategies have been considered to address these challenges and effectively improve the membrane performances. Alteration of membrane properties strategy using suitable nanofillers such us poly (amido amine) or PAMAM has been largely studied. Herein, research efforts regarding the synthesis and properties of PAMAM along with the synthesis of PAMAM multifunctional nanocomposites were concisely reviewed for the first time. Membrane performance enhancement by incorporation of PAMAM were reviewed and discussed. Results and contributions achieved in the improvement of PAMAM incorporated membranes for the treatment of different types of wastewaters has been reviewed and summarized. Furthermore, perspectives on the current challenges and future research needs in the development and application of PAMAM incorporated polymeric membranes to benefit from the potentials that offer these promising new membrane nanofiller were discussed, [ABSTRACT FROM AUTHOR]

The present study was aimed to synthesize, characterize, and evaluate the angiopep-2 grafted PAMAM dendrimers (Den, G 3.0 NH 2 ) with and without PEGylation for the targeted and better delivery approach of temozolomide (TMZ) for the management of glioblastoma multiforme (GBM). Den-ANG and Den-PEG 2 -ANG conjugates were synthesized and characterized by 1 H NMR spectroscopy. The PEGylated (TMZ@Den-PEG 2 -ANG) and non-PEGylated (TMZ@Den-ANG) drug loaded formulations were prepared and characterized for particle size, zeta potential, entrapment efficiency, and drug loading. An in vitro release study at physiological (pH 7.4) and acidic pH (pH 5.0) was performed. Preliminary toxicity studies were performed through hemolytic assay in human RBCs. MTT assay, cell uptake, and cell cycle analysis were performed to evaluate the in vitro efficacy against GBM cell lines (U87MG). Finally, the formulations were evaluated in vivo in a Sprague-Dawley rat model for pharmacokinetics and organ distribution analysis. The 1 H NMR spectra confirmed the conjugation of angiopep-2 to both PAMAM and PEGylated PAMAM dendrimers, as the characteristic chemical shifts were observed in the range of 2.1 to 3.9 ppm. AFM results revealed that the surface of Den-ANG and Den-PEG 2 -ANG conjugates were rough. The particle size and zeta potential of TMZ@Den-ANG were observed to be 229.0 ± 17.8 nm and 9.06 ± 0.4 mV, respectively, whereas the same for TMZ@Den-PEG 2 -ANG were found to be 249.6 ± 12.9 nm and 10.9 ± 0.6 mV, respectively. The entrapment efficiency of TMZ@Den-ANG and TMZ@Den-PEG 2 -ANG were calculated to be 63.27 ± 5.1% and 71.48 ± 4.3%, respectively. Moreover, TMZ@Den-PEG 2 -ANG showed a better drug release profile with a controlled and sustained pattern at PBS pH 5.0 than at pH 7.4. The ex vivo hemolytic study revealed that TMZ@Den-PEG 2 -ANG was biocompatible in nature as it showed 2.78 ± 0.1% hemolysis compared to 4.12 ± 0.2% hemolysis displayed by TMZ@Den-ANG. The outcomes of the MTT assay inferred that TMZ@Den-PEG 2 -ANG possessed maximum cytotoxic effects against U87MG cells with IC 50 values of 106.62 ± 11.43 μM (24 h) and 85.90 ± 9.12 μM (48 h). In the case of TMZ@Den-PEG 2 -ANG, the IC 50 values were reduced by 2.23-fold (24 h) and 1.36-fold (48 h) in comparison to pure TMZ. The cytotoxicity findings were further confirmed by significantly higher cellular uptake of TMZ@Den-PEG 2 -ANG. Cell cycle analysis of the formulations suggested that the PEGylated formulation halts the cell cycle at G2/M phase with S-phase inhibition. In the in vivo studies, the half-life ( t 1/2 ) values of TMZ@Den-ANG and TMZ@Den-PEG 2 -ANG were enhanced by 2.22 and 2.76 times, respectively, than the pure TMZ. After 4 h of administration, the brain uptake values of TMZ@Den-ANG and TMZ@Den-PEG 2 -ANG were found to be 2.55 and 3.35 times, respectively, higher than that of pure TMZ. The outcomes of various in vitro experiments promoted the use of PEGylated nanocarriers for the management of GBM. Angiopep-2 grafted PEGylated PAMAM dendrimers can be potential and promising drug carriers for the targeted delivery of antiglioma drugs directly to the brain.ex vivo experiments promoted the use of PEGylated nanocarriers for the management of GBM. Angiopep-2 grafted PEGylated PAMAM dendrimers can be potential and promising drug carriers for the targeted delivery of antiglioma drugs directly to the brain.

Introduction: Polyamidoamine (PAMAM) dendrimers are a unique family of dendritic polymers with numerous pharmaceutical and biomedical applications. One major problem with these polymers is their cytotoxicity. The purpose of this study is to synthesize novel dendrimers with aldehyde terminal groups and compare their cytotoxicity with that of dendrimers containing amine terminated groups. Methods: G1 (first generation) and G2 (second generation) dendrimers with amine terminated groups were synthesized by divergent method and then the amine terminated groups were converted to the aldehyde groups using surface modification of the functional group inversion (FGI) method. The cytotoxicity of the novel G1 and G2 polyamidoaldehyde (PAMAL) dendrimers together with that of G1 and G2 PAMAM-NH2 dendrimers was investigated by MTT assay using MCF-7 cell line. Results: The results showed that cytotoxicity of dendrimers with aldehyde terminated groups is much lower than that of G1 and G2 PAMAM-NH2 dendrimers. Conclusion: Dendrimers with aldehyde terminated groups could be used as novel and convenient carriers for drug delivery with low cytotoxic effect compared with the amine terminated denderimers. The results revealed that the same generations of the dendrimers with aldehyde-terminated groups are far less toxic than the corresponding amine-terminated denderimer.

Dendrimers are nanoscopic compounds, which are monodispersed, and they are generally considered as homogeneous. PAMAM (polyamidoamine) was introduced in 1985, by Donald A. Tomalia, as a new class of polymers, named ‘starburst polymers’. This important contribution of Professor Tomalia opened a new research field involving nanotechnological approaches. From then on, many groups have been using PAMAM for diverse applications in many areas, including biomedical applications. The possibility of either linking drugs and bioactive compounds, or entrapping them into the dendrimer frame can improve many relevant biological properties, such as bioavailability, solubility, and selectivity. Directing groups to reach selective delivery in a specific organ is one of the advanced applications of PAMAM. In this review, structural and safety aspects of PAMAM and its derivatives are discussed, and some relevant applications are briefly presented. Emphasis has been given to gene delivery and targeting drugs, as advanced delivery systems using PAMAM and an incentive for its use on neglected diseases are briefly mentioned.

Dendrimeric Antigens (DeAns) consist of dendrimers decorated with multiple units of drug antigenic determinants. These conjugates have been shown to be a powerful tool for diagnosing penicillin allergy using in vitro immunoassays, in which they are recognized by specific IgE from allergic patients. Here we propose a new diagnostic approach using DeAns in cellular tests, in which recognition occurs through IgE bound to the basophil surface. Both IgE molecular recognition and subsequent cell activation may be influenced by the tridimensional architecture and size of the immunogens. Structural features of benzylpenicilloyl-DeAn and amoxicilloyl-DeAn (G2 and G4 PAMAM) were studied by diffusion Nuclear Magnetic Resonance (NMR) experiments and are discussed in relation to molecular dynamics simulation (MDS) observations. IgE recognition was clinically evaluated using the basophil activation test (BAT) for allergic patients and tolerant subjects. Diffusion NMR experiments, MDS and cellular studies provide evidence that the size of the DeAn, its antigen composition and tridimensional distribution play key roles in IgE-antigen recognition at the effector cell surface. These results indicate that the fourth generation DeAns induce a higher level of basophil activation in allergic patients. This approach can be considered as a potential complementary diagnostic method for evaluating penicillin allergy.

Dendrimers have come a long way in the last 25 years since their inception. Originally created as a wonder molecule of chemistry, dendrimer is now in the fourth class of polymers. Dr. Donald Tomalia first published his seminal work on Poly(amidoamine) (PAMAM) dendrimers in 1985. Application of dendrimers as a drug delivery system started in late 1990s. Dendrimers for drug delivery are employed using two approaches: (i) formulation and (ii) nanoconstruct. In the formulation approach, drugs are physically entrapped in a dendrimer using non-covalent interactions, whereas drugs are covalently coupled on dendrimers in the nanoconstruct approach. We have demonstrated the utility of PAMAM dendrimers for enhancing solubility, stability and oral bioavailability of various drugs. Drug entrapment and drug release from dendrimers can be controlled by modifying dendrimer surfaces and generations. PAMAM dendrimers are also shown to increase transdermal permeation and specific drug targeting. Dendrimer platforms can be engineered to attach targeting ligands and imaging molecules to create a nanodevice. Dendrimer nanotechnology, due to its multifunctional ability, has the potential to create next generation nanodevices.

Tissue adhesives based on polyamidoamine (PAMAM) dendrimer, grafted with UV-sensitive aryldiazirine (PAMAM-g-diazirine) are promising new candidates for light active adhesion on soft tissues. Diazirine carbene precursors form interfacial and intermolecular covalent crosslinks with tissues after UV light activation that requires no premixing or inclusion of free radical initiators. However, primary amines on the PAMAM dendrimer surface present a potential risk due to their cytotoxic and immunological effects. PAMAM-g-diazirine formulations with cationic pendant amines converted into neutral amide groups were evaluated. In vitro toxicity is reduced by an order of magnitude upon amine capping while retaining bioadhesive properties. The in vivo immunological response to PAMAM-g-diazirine formulations was found to be optimal in comparison to standard poly(lactic-co-glycolic acid) (PLGA) thin films.

The biosensors based on PL/PEDOT and PAMAM/PL/PEDOT for acetamiprid can be effectively constructed through both the increase of differential pulse voltammetry (DPV) signal change and the increase of the chronoamperometry (CA) signal change. [Display omitted] • The electrochemical biosensors were prepared based on PEDOT, PL and PAMAM. • The prepared PL/PEDOT composite exhibited high surface area and excellent conductivity. • PAMAM dendrimer can greatly enhance the sensing performance. • The biosensors were able to detect acetamiprid in real samples. The cumulative harm caused by pesticide residues to environmental safety and human health is enormous, and the sensitive and selective detection pesticide in very trace amounts is currently a challenge. Herein, the biosensors for the ultrasensitive detection of acetamiprid (ACE) were proposed. The conducting polymer composite of phaseoloidin doped poly(3,4-ethyloxythiophene) (PL/PEDOT) was prepared with high surface area, excellent conductivity and stability, which was followed by the functionalization with poly(amidoamine) of the third generation (PAMAM). ACE aptamers were immobilized onto the platforms (PL/PEDOT and PAMAM/PL/PEDOT) for the development of ACE aptasensors. The concentration of ACE can be measured through both the increase of differential pulse voltammetry (DPV) signal change and the increase of the chronoamperometry (CA) signal change from the reduction of hydrogen peroxide catalyzed by PL/PEDOT. The ACE aptasensor based on PAMAM/PL/PEDOT exhibited linear ranges of 0.1 pg mL−1-10 ng mL−1 and 0.1 fg-1.0 pg mL−1, the detection limits as low as 0.0117 pg mL−1 and 0.0355 fg mL−1 (S/N = 3) through DPV and CA, respectively. Significantly, the response sensitivity of DNA/PAMAM/PL/PEDOT/GCE was 3.11 times higher than that of DNA/PL/PEDOT/GCE (by CA mode), proving that the PAMAM dendrimer can greatly enhance the sensing performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydroxyl-terminated dendrimer was effectively synthesized using a divergent strategy. • The effect of several factors on sorption capacity of dendrimer for metal uptake was studied. • The interaction of metal and dendrimer was revealed by TGA studies and FT-IR to confirm metal-dendrimer complex. Environmental pollution is not a recent phenomenon, but it continues to be the greatest threat to humanity and the main factor in environmental morbidity and mortality. The health of people is threatened by heavy metals because of growing industrial activity over the past century. More effort has gone into identifying the most effective methods for adsorbing heavy metal ions and also it is essential to develop new materials for the adsorption of heavy metals due to their great resistance and protracted presence in the environment. Dendrimer is a good way to remove a bulky metal. Using 1,3-bis(4,6-dichloro-1,3,5-triazine-2-yl)thiourea as the backbone of dendrimer, we construct hydroxyl-terminated dendrimer up to generation three. Fourier Transform Infrared Spectroscopy (FT-IR), Transmission electron microscopy (TEM), Mass Spectroscopy, 1H NMR spectroscopy and 13C NMR spectroscopy data were used to describe the dendrimer structure. For the purpose of removing metal ions, synthesized sorbent was tested with aqueous solutions of Ni(II), Co(II) and Zn(II) ions using various parameters like pH, time, and generations were used to evaluate the sorption capabilities of synthesized dendrimers. Fourier transform infrared (FT-IR) techniques and thermo gravimetric analysis (TGA) were used to examine dendrimer-metal complexes. The results of the study show that dendrimer products with higher generations have better sorption properties than dendrimer products with lower generations. [ABSTRACT FROM AUTHOR]

[Display omitted] • This article proposed an efficient method to prepare hydrogel. • Polyamido-amine was introduced into the hydrogel to improve the content of nitrogen. • The hydrogel has a good adsorption and removal effect on cadmium and copper ions. • The adsorption mechanism of hydrogel has been studied. • The hydrogel has a certain selective adsorption capacity. As a new functional polymer material with three-dimensional polymer network structure, hydrogel is widely used in the removel of heavy metal ions pollutants in sewage. In this work, semi-dissolution acidification sol–gel transition method was used to prepare the hydrogel with chitosan/sodium alginate/calcium ion (CTS/SA/Ca2+) physical cross-linked double network structure without adding chemical cross-linking agent. Meanwhile, hyperbranched polyamide-amine with different generations which was rich in amino groups were introduced to improve the adsorption capacity of hydrogel, and the CTS/PAMAM/SA/Ca2+ hydrogel adsorbent with no secondary pollution, environmental protection and high adsorption capacity was obtained. Experimental results show that the hydrogel with third-generation hyperbranched polyamide-amine have the best comprehensive performance. Its maximum adsorption capacities for copper ions and cadmium ions could reach 174.82 mg/g and 157.72 mg/g respectively. Furthermore, it was found that the adsorption behaviors of copper ions and cadmium ions on the hydrogel conformed to the pseudo-second-order kinetic model and Langmuir adsorption isotherm model by studying the factors affecting the adsorption process. The CTS/PAMAM/SA/Ca2+ hydrogel has the advantages of high heavy metal ion adsorption capacity, uniform structure, and recyclability. As a functional material with simple preparation and excellent performance, it has good application potential and research value. [ABSTRACT FROM AUTHOR]

The wide-band-gap inorganic CsPbI 2 Br perovskite material provides a highly matched absorption range with the indoor light spectrum and is expected to be used in the fabrication of highly efficient indoor photovoltaic cells (IPVs) and self-powered low-power Internet of Things (IoT) sensors. However, the defects that cause nonradiative recombination and ion migration are assumed to form leakage loss channels, resulting in a severe impact on the open-circuit voltage ( V ) and the fill factor (FF) of IPVs. Herein, we introduce poly(amidoamine) (PAMAM) dendrimers with multiple passivation sites to fully repair the leakage channels in the devices, taking into account the characteristics of IPVs that are extremely sensitive to nonradiative recombination and shunt resistance. The as-optimized IPVs demonstrate a promising PCE of 35.71% under a fluorescent light source (1000 lux), with OC ) and the fill factor (FF) of IPVs. Herein, we introduce poly(amidoamine) (PAMAM) dendrimers with multiple passivation sites to fully repair the leakage channels in the devices, taking into account the characteristics of IPVs that are extremely sensitive to nonradiative recombination and shunt resistance. The as-optimized IPVs demonstrate a promising PCE of 35.71% under a fluorescent light source (1000 lux), with V OC increased from 0.99 to 1.06 V and FF improved from 75.21 to 84.39%. The present work provides insight into the photovoltaic mechanism of perovskites under full sun and indoor light, which provides guidance for perovskite photovoltaic technology with industrialization prospects.

The in vivo impact of two generation 6 cationic polyamidoamine (PAMAM) dendrimers on cellular signaling via extracellular-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (p38 MAPK), as well as their relationship to epidermal growth factor receptor (EGFR), were studied in the normal and/or diabetic rat kidney. A single 10 mg/kg/i.p administration of Polyfect (PF; with an intact branching architecture) or Superfect (SF; with a fragmented branching architecture) modulated renal ERK1/2 and p38 MAPK phosphorylation in a dendrimer-specific and animal model-dependent manner. AG1478 treatment (a selective EGFR inhibitor) confirmed that renal ERK1/2 and p38 MAPK signaling was downstream of EGFR. Surprisingly, both PAMAMs induced hyperphosphorylation of ERK1/2 and p38 MAPK (at 1 or 5 mg/kg) despite inhibiting EGFR phosphorylation in the diabetic kidney. PAMAMs did not alter renal morphology but their effects on p38 MAPK and EGFR phosphorylation were reversed by ex vivo treatment of kidneys with the anti-oxidant, Tempol. Thus, PAMAMs can intrinsically modulate signaling of mitogen-activated protein kinases (MAPKs) depending on the type of dendrimer (fragmented vs intact branching architecture) and animal model (normal vs diabetic) used and likely occurs via an EGFR-independent and oxidative-stress dependent mechanism. These findings might have important toxicological implications for PAMAM-based delivery systems. [ABSTRACT FROM AUTHOR]

Objectives The objective of this study was to investigate the effects of poly (amido amine) (PAMAM), composite with nanoparticles of amorphous calcium phosphate (NACP), and the combined PAMAM + NACP nanocomposite treatment, on remineralization of demineralized dentin in a cyclic artificial saliva/lactic acid environment for the first time. Methods Dentin specimens were prepared and demineralized with 37% phosphoric acid for 15 s. Four groups were prepared: (1) dentin control, (2) dentin coated with PAMAM, (3) dentin with NACP composite, (4) dentin with PAMAM + NACP. Specimens were treated with a cyclic artificial saliva/lactic acid regimen for 21 days. Acid neutralization and calcium (Ca) and phosphate (P) ion concentrations were measured. The remineralized dentin specimens were examined by scanning electron microscopy (SEM) and hardness testing. Results NACP nanocomposite had mechanical properties similar to commercial control composites (p > 0.1). NACP composite had acid-neutralization and Ca and P ion release capability. PAMAM or NACP composite each alone achieved remineralization and increased the hardness of demineralized dentin (p < 0.05). PAMAM + NACP nanocomposite achieved the greatest mineral regeneration in demineralized dentin and the greatest hardness increase in demineralized dentin, which approached the hardness of healthy dentin (p > 0.1). Significance The superior remineralization efficacy of PAMAM + NACP was demonstrated for the first time. PAMAM + NACP induced remineralization in demineralized dentin in an acid challenge environment, when conventional remineralization methods such as PAMAM did not work well. The novel PAMAM + NACP composite approach is promising for a wide range of dental applications to inhibit caries and protect tooth structures. [ABSTRACT FROM AUTHOR]

Starting fromEthylenediamine(EDA) or poly(ethylene glycol) tetra amine (4-arm-PEG) cores, two different peripheral methylester (–COOCH3) or amine (–NH2) PAMAM dendrimers have been synthesized. In the growth phase of dendrimers, two important building blocks, methyl acrylate for the half generation and EDA for the full generations, have been used. In order to improve the yield and decrease the time for the aminolysis step, a microwave-assisted technique was applied. Both of these dendrimers with different cores were grown up to 4.5 generations where surface modification, i.e. PEGylation, with 10%Poly(ethylene glycol) bis(amine) was performed. In order to increase the solubility of dendrimers, esteric surfaces were converted to carboxylic acid groups. Accordingly, the dendrimers were soluble in water or in water–methanol mixture which enabled their purification by liquid-phase polymer-based retention in each step. Finally, the resulting products that were characterized with (NMR and FTIR) spectroscopy were evaluatedin vitroandin vivo. The analytical grade dendrimers were not cytotoxic to mouse fibroblasts and their biodistribution was mainly determined in the site of injection (peritoneum), liver and kidneys. [ABSTRACT FROM PUBLISHER]

A sequence of generations of polyamidoamine dendron modified-talc, PAMAM-talc-Gn (n = 1, 3, 5 and 7), is proposed as additive in a composite gel electrolyte for dye-sensitized solar cells. Polyiodides are intercalated into the organotalc interlamellar space by adsorption of iodine vapor, producing triiodide and polyiodides. We investigate the effect of organotalc content on the charge transport in the electrolyte and solar cell performance and optimize the organotalc content. Without the previous adsorption of iodine molecules, the organotalcs appear to remove iodine from the electrolyte solution decreasing device’s performance significantly. Instead, the samples with additional iodide had higher J sc and efficiency approaching the values of the reference cells containing liquid, which suggests that this kind of gelling method would be suitable for dye solar cells. Charge transport in the gel electrolyte is investigated with electrochemical impedance spectroscopy and cyclic voltammetry analyses using symmetrical CE-CE electrochemical cells. [ABSTRACT FROM AUTHOR]

This study aimed to synthesize a dual-modal magnetic resonance imaging (MRI)/fluorescence imaging (FLI) nanoprobe in order to detect atherosclerosis. Herein, we had prepared the polyamidoamine-graft-poly (ethylene glycol) (PAMAM-g-PEG) as the carrier. Dextran sulfate (DS) and Rhodamine B (RB) were grafted to PAMAM-g-PEG continuously through reductive amination and amidation reaction to synthesize PAMAM-g-PEG-g-DS-g-RB. The structure of PAMAM-g-PEG-g-DS-g-RB was characterized through nuclear magnetic resonance (1H-NMR) and Fourier transform infrared spectroscopy (FTIR). A new water-soluble superparamagnetic iron oxide nanoparticles (IONPs) has been synthesized through simple ligand exchange between the iron oxide nanaparticles and PAMAM-g-PEG-g-DS-g-RB. The analysis of transmission electron microscopy (TEM) indicated that micelles were well dispersed in water and had uniform sizes. The result of thermogravimetric analysis (TGA) proved that about 83% (mass fraction) polymers were coated on the surface of IONPs. The MRI in vitro evaluation demonstrated a high R2 value (130.8 mM−1s−1) to be served as a T2-weighted contrast agent. The cell counting kit (CCK) assay showed no significant toxicity in RAW264.7. The above results confirmed that PAMAM-g-PEG-g-DS-g-RB@IO could play an significant role of MRI and FLI in the atherosclerosis. [ABSTRACT FROM AUTHOR]

This article reports on the synthesis of water dispersible carbon quantum dots (CDs) by a one-step hydrothermal method using polyamidoamine (PAMAM) and (3-aminopropyl)triethoxysilane (APTES) as a platform and passivant. The resulting CDs are highly uniform and finely dispersed. The synergistic effect between PAMAM and APTES on the surface of the CDs results in a fluorescence that is much brighter than that of CDs modified with either APTES or PAMAM only. The fluorescence of the co-modified CDs is quenched by Hg(II) ions at fairly low concentrations. Under the optimum conditions, the intensity of quenched fluorescence drops with Hg(II) concentration in the range from 0.2 nM to 10 μM, and the detection limit is 87 fM. The effect of potentially interfering cations on the fluorescence revealed a high selectivity for Hg. The fluorescent probe was applied to the determination of Hg(II) in (spiked) waters and milk and gave recoveries between 95.6 and 107 %, with relative standard deviation between 4.4 and 6.0 %. [ABSTRACT FROM AUTHOR]

In this work, a centri-voltammetric cytosensor suitable for the for detection of folate receptor positive cervical cancer (HeLa) cells was developed for the first time. In order to see the effect of centrifugation, developed cytosensor’s performance was compared in terms of analytical characteristics values, in the presence and absence of centri-voltammetry. As a result, in the absence of centri-voltammetry, the linear range was found between 75 cells/mL and 10 6 cells/mL with limit of detection (LOD) value as 75 cells/mL and with R.S.D value of 3.5% (for 5.0 × 10 4 HeLa cells/mL (n = 3)). Meanwhile in the presence of centri-voltammetry, the linear range was found between 8.0 cells/mL and 5 × 10 6 cells/mL and LOD value was calculated as 8 cells/mL with R.S.D value of 4.7% for the same concentration. [ABSTRACT FROM AUTHOR]

Alumina nanotubes are surface-conjugated with polyamidoamine (PAMAM) dendrimers of the third generation, aimed at obtaining novel nanomaterials for drug delivery applications. The structure and surface properties of PAMAM-conjugated alumina nanotubes (PAMAM-Al2O3NT) are characterized using Fourier Transform Infrared spectroscopy, solid state 13C-RMN, transmission electron microscopy, N2 adsorption-desorption isotherms, X-ray powder diffraction (XRD), and thermogravimetric analysis (TGA), which supported for a 3.0 wt% of PAMAM grafting in the prepared product. The drug loading and releasing properties of PAMAM-Al2O3NT are examined using three model therapeutic compounds, namely, curcumin, methotrexate, and silibinin, showing that PAMAM conjugation enhances the drug loading capacity and drug-adsorbent affinity compared to pristine Al2O3NT systems. Additionally, Alamar Blue cell viability assays reveal that PAMAM-Al2O3NT are not cytotoxic materials over a wide concentration range. These results suggest that PAMAM-Al2O3NT are potential nanostructured vehicles for drug delivery applications. [ABSTRACT FROM AUTHOR]

α2,3-Sialylated glycans (α2,3-sial-Gs) are crucial molecular targets for cancer diagnosis and clinical research. We describe a biosensor for detecting α2,3-sial-Gs that is based on the specific recognition by the Maackia amurensis lectin (MAL). A glassy carbon electrode was modified with carboxy-modified MWCNTs and a polyamidoamine dendrimer (PAMAM). The PAMAM is highly branched and contains many amino groups. MAL was immobilized on the modified electrode to create a sensor capable of detecting α2,3-sial-Gs (at a working voltage of 0.2 V vs. SCE) in the 10 fg⋅mL to 50 ng⋅mL concentration range and with a detection limit as low as 3 fg⋅mL (at an S/N ratio of 3). This approach may pave the way to detection schemes for other proteins and glycans if appropriate affinity binding pairs are available. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The interaction between PAMAM G0 and gold nanoclusters Au n ( n = 2, 4, 6, and 8) was studied theoretically at DFT level. Different coordination sites were explored, including internal and superficial coordination. All stable complexes exhibited external interaction with the amine or carbonyl site, while the core site coordination was not favored. The more stable binding of Au n was registered with the terminal amine group, while the binding at the amide site was relatively weaker. The vertical first ionization potential, electron affinity, Fermi level, and the HOMO–LUMO gap of PAMAM and Au n –PAMAM G0 complexes were also analyzed. [ABSTRACT FROM AUTHOR]

Adenovirus (Ad)-mediated cancer gene therapy has been proposed as a promising alternative to conventional therapy for cancer. However, success of systemically administered naked Ad has been limited due to the immunogenicity of Ad and the induction of hepatotoxicity caused by Ad's native tropism. In this study, we synthesized an epidermal growth factor receptor (EGFR)-specific therapeutic antibody (ErbB)-conjugated and PEGylated poly(amidoamine) (PAMAM) dendrimer (PPE) for complexation with Ad. Transduction of Ad was inhibited by complexation with PEGylated PAMAM (PP) dendrimer due to steric hindrance. However, PPE-complexed Ad selectively internalized into EGFR-positive cells with greater efficacy than either naked Ad or Ad complexed with PP. Systemically administered PPE-complexed oncolytic Ad elicited significantly reduced immunogenicity, nonspecific liver sequestration, and hepatotoxicity than naked Ad. Furthermore, PPE-complexed oncolytic Ad demonstrated prolonged blood retention time, enhanced intratumoral accumulation of Ad, and potent therapeutic efficacy in EGFR-positive orthotopic lung tumors in comparison with naked Ad. We conclude that ErbB-conjugated and PEGylated PAMAM dendrimer can efficiently mask Ad's capsid and retarget oncolytic Ad to be efficiently internalized into EGFR-positive tumor while attenuating toxicity induced by systemic administration of naked oncolytic Ad. [ABSTRACT FROM AUTHOR]

Green tea polyphenols have attracted significant interest due to their promising therapeutic potential as antitumor agents. These include catechins that have been explored for various tumors with minimal side effects. This paper demonstrates the fabrication and characterization of dendrimerized magnetic nanoparticles, as delivery vectors for epigallocatechin gallate (EGCG). Glutamic acid-functionalized iron oxide nanoparticles (Glu–Fe3O4) were synthesized and modified with the polyethylene glycol polyamidoamine dendrimers of generations 3, 5, and 6. Nanoparticles were characterized by X-ray diffraction, electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. In aqueous colloidal suspensions, they showed a rapid temperature increase under varying magnetic fields, suggesting their potential in chemothermal therapeutic applications. The loading efficiency of the dendrimerized nanoparticles was calculated to be 32.7%, 51.1%, and 56.4% for generations 3, 5, and 6, respectively. In acidic environments, a sustained drug release profile with an increasing but incomplete release was observed. Importantly, EGCG-loaded nanoparticles induced controlled cell death in human cervical cancer cells, demonstrating a 40% reduction in cell population over 24 h at the highest concentration used, with a linear dose-response. [ABSTRACT FROM AUTHOR]

Ochratoxin A (OTA) is a carcinogenic mycotoxin that contaminates food such as cereals, wine and beer; therefore it represents a risk for human health. Consequently, the allowed concentration of OTA in food is regulated by governmental organizations and its detection is of major agronomical interest. In the current study we report the development of an electrochemical aptasensor able to directly detect trace OTA without any amplification procedure. This aptasensor was constructed by coating the surface of a gold electrode with a film layer of modified polypyrrole (PPy), which was thereafter covalently bound to polyamidoamine dendrimers of the fourth generation (PAMAM G4). Finally, DNA aptamers that specifically binds OTA were covalently bound to the PAMAM G4 providing the aptasensor, which was characterized by using both Atomic Force Microscopy (AFM) and Surface Plasmon Resonance (SPR) techniques. The study of OTA detection by the constructed electrochemical aptasensor was performed using Electrochemical Impedance Spectroscopy (EIS) and revealed that the presence of OTA led to the modification of the electrical properties of the PPy layer. These modifications could be assigned to conformational changes in the folding of the aptamers upon specific binding of OTA. The aptasensor had a dynamic range of up to 5 μg L −1 of OTA and a detection limit of 2 ng L −1 of OTA, which is below the OTA concentration allowed in food by the European regulations. The efficient detection of OTA by this electrochemical aptasensor provides an unforeseen platform that could be used for the detection of various small molecules through specific aptamer association. [ABSTRACT FROM AUTHOR]

A catalyst that Pt nanoparticles (NPs) anchored on hollow silica nanospheres modified by polyamidoamine (PAMAM) dendrimers was synthesized (marked as hollow SiO-G1-Pt). The hollow silica nanospheres were facilely prepared through etching the template of ZnO nanospheres. Pt NPs exhibited small size (around 2.32 nm) and uniform dispersion owing to the unique physicochemical property of the dendrimers. The catalytic performances of as-prepared catalysts were evaluated with the reduction of p-nitrophenol by NaBH. The results showed the fabricated hollow SiO-G1-Pt catalyst exhibited the excellent catalytic activity, which was higher than that of Pt NPs deposited on hollow silica without grafting of PAMAM dendrimers and Pt NPs loaded on PAMAM-modified ZnO@SiO. Moreover, the results of recycling experiments revealed hollow SiO-G1-Pt possessed convenient separation and the similar catalytic performance without visible reduction after five runs. [ABSTRACT FROM AUTHOR]

Polyamidoamine (PAMAM) dendrimers were used to produce CdSe core/multi-shell fluorescent quantum dots (QDs) which are colloidally stable in aqueous solutions. The size, charge, and optical properties of QDs functionalized with the 4th (G4) and 5th (G5) generation of PAMAM were compared with amphiphilic polymer-covered QDs and used as criteria for the evaluation of the suitability of both water solubilization methods. As revealed by dynamic and electrophoretic light scattering (DLS and ELS), the hydrodynamic sizes of the QDs varied from 30 to 65 nm depending on QD type and dendrimer generation, with all QDs displaying highly positive surface charges, i.e., zeta potentials of around +50 mV in water. PAMAM functionalization yielded stable core/multi-shell QDs with photoluminescence quantum yields ( Φ) of up to 45 %. These dendrimer-covered QDs showed a smaller decrease in their Φ upon phase transfer compared with QDs made water soluble via encapsulation with amphiphilic brush polymer bearing polyoxyethylene/polyoxypropylene chains. [ABSTRACT FROM AUTHOR]

Triazine and PAMAM dendrimers of similar size and number of cationic surface groups were compared for their ability to promote platelet aggregation. Triazine dendrimers (G3, G5 and G7) varied in molecular weight from 8 kDa-130 kDa and in surface groups 16-256. PAMAM dendrimers selected for comparison included G3 (7 kDa, 32 surface groups) and G6 (58 kDa, 256 surface groups). The treatment of human platelet-rich plasma (PRP) with low generation triazine dendrimers (0.01-1 μM) did not show any significant effect in human platelet aggregation in vitro; however, the treatment of PRP with larger generations promotes an effective aggregation. These results are in agreement with studies performed with PAMAM dendrimers, where large generations promote aggregation. Triazine dendrimers promote aggregation less aggressively than PAMAM dendrimers, a factor attributed to differences in cationic charge or the formation of supramolecular assemblies of dendrimers. [ABSTRACT FROM AUTHOR]

Different generations (G1, G2 and G3) of polyamidoamine dendrimers (PAMAM) were synthesized and co-spray dried with rifampicin to produce inhalable microspheric particles for pulmonary delivery. The particle size distribution, morphology and density of the designed formulations were characterized by laser diffraction, scanning electron microscopy (SEM) and helium densitometer, respectively. The aerosolization performance of these formulations was investigated using an Andersen cascade impactor. The formulations were efficient aerosols having favorable fine particle fraction (FPF) and emitted fraction (EF), suggesting that the powders were suitable for inhalation. The absorptions of rifampicin following pulmonary administration of different formulations were also examined using an in situ pulmonary absorption method. The pharmacokinetic profiles of different rifampin formulations were studied following intrapulmonary administrations for 60 h. The pharmacokinetics parameters such as C max , t max , t 1/2 , mean residence time (MRT) and the AUC were calculated separately. It was evident that the t max value of the formulations was decreased while C max value was increased followed by PAMAM dendritic generations increased from G1 to G3. The lower generation PAMAM microspheres were found to have significant impact on the pharmacokinetics parameters of rifampicin and ultimately drug bioavailability. In this study, PAMAM G3 dendritic microsphere was identified as suitable drug carriers for the pulmonary delivery of rifampicin into lung tissues. [ABSTRACT FROM AUTHOR]

In this research, different generations of PAMAM-grafted chitosan as integrated biosorbents were successfully synthesized via step by step divergent growth approach of dendrimer. The synthesized products were utilized as adsorbents for heavy metals (Pb 2+ in this study) removing from aqueous solution and their reactive Pb 2+ removal potential was evaluated. The results showed that as-synthesized products with higher generations of dendrimer, have more adsorption capacity compared to products with lower generations of dendrimer and sole chitosan. Adsorption capacity of as-prepared product with generation 3 of dendrimer is 18 times more than sole chitosan. Thermodynamic and kinetic studies were performed for understanding equilibrium data of the uptake capacity and kinetic rate uptake, respectively. Thermodynamic and kinetic studies showed that Langmuir isotherm model and pseudo second order kinetic model are more compatible for describing equilibrium data of the uptake capacity and kinetic rate of the Pb 2+ uptake, respectively. [ABSTRACT FROM AUTHOR]

We report the potential of carbon nanodots (CNDs) as a molecular scaffold for enhancing the antimicrobial activities of small dendritic poly(amidoamines) (PAMAM). Carbon nanodots prepared from sago starch are readily functionalized with PAMAM by using N -ethyl-N′-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N -hydroxysuccinimide (NHS). Electron microscopy images of these polyaminated CNDs show that they are approximately 30–60 nm in diameter. Infrared and fluorescence spectroscopy analyses of the water-soluble material established the presence of the polyamidoaminated moiety and the intrinsic fluorescence of the nanodots. The polyaminated nanodots ( CND-PAM1 and CND-PAM2 ) exhibit in vitro antimicrobial properties, not only to non-multidrug resistant bacteria but also to the corresponding Gram-negative multidrug bacteria. Their minimum inhibitory concentration (MIC) ranges from 8 to 64 μg/mL, which is much lower than that of PAMAM G1 or the non-active PAMAM G0 and CNDs. Additionally, they show synergistic effect in combination with tetracycline or colistin. These preliminary results imply that CNDs can serve as a promising scaffold for facilitating the rational design of antimicrobial materials for combating the ever-increasing threat of antibiotic resistance. Moreover, their fluorescence could be pertinent to unraveling their mode of action for imaging or diagnostic applications. [ABSTRACT FROM AUTHOR]

This paper describes the preparation and characterization of biocathodes for a methanol/O 2 biofuel cell using the crude extract and a purified laccase from a strain of Pycnoporus sanguineus (PyS). The biocathode assembly with mediated electron transfer was achieved by immobilizing either the enzymes in the crude extract or the purified laccase with polyamidoamine (PAMAM) dendrimers on top of a polypyrrole matrix containing entrapped 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) species as the redox mediator. Carbon nanotubes modified with anthracene moieties were used to orientate the purified laccase and allow for direct bioelectrocatalytic O 2 reduction. The kinetic characterization of the biocathodes showed that samples prepared with either the crude extract or the purified laccase retained ABTS oxidation activity after the immobilization procedure. The biofuel cell tests showed that the biocathodes were able to furnish maximum power densities of 51.2 and 99.8 μW cm − 2 for the samples prepared with the crude extract and the purified enzyme, respectively. Moreover, it was observed that both biocathodes tested displayed a very similar loss in power performance as a function of storage time, reaching 60% of the initial activity after 60 days. Overall, the laccase-based biocathodes prepared either with the crude extract or with the purified enzyme are able to provide electrochemically active and stable biomaterials. [ABSTRACT FROM AUTHOR]

Native and PEGylated poly-amidoamine-G4 (PAMAM-G4) dendrimers with PEGylation degrees of 0%, 28%, 34%, 67%, and 100% are evaluated as potential drug carriers for methotrexate (MTX). A maximum complex stoichiometry of 47:1 is obtained for the system with 34% of PEGylation, with an estimated binding constant of 1.2 × 104 mol−1 per binding site, as derived from aqueous solubility profiles. 2D-NOESY experiments reveal a preferential complexation of MTX within PAMAM-G4 branches, suggesting that high PEGylation ratios restrict drug diffusion toward innermost PAMAM cavities. On the other hand, high PEGylation degrees considerably decrease the rate of MTX release, which can be attributed to a reduced dendrimer swelling due to surface polyethylene glycol crowding. All release profiles follow first-order kinetics, suggesting a diffusion-controlled mechanism for MTX release. These results can be helpful to understand the molecular basis underlying the complexation and release of MTX with PEGylated PAMAM dendrimers aimed at designing more efficient drug delivery systems. [ABSTRACT FROM AUTHOR]

Short circulation is a disadvantage of dendrimers as drug delivery carriers due to their small size. In this work, pH-sensitive morpholino-terminated generation 5 poly(amido amine) (PAMAM) is prepared. At neutral pH, the dendrimer has a hydrophilic neutral surface and thereby stealth property. Under tumor acidic environments, the dendrimer develops positive charges due to protonation of the morpholino groups, and cellular uptake of the dendrimer is subsequently enhanced. The dendrimer is predicted to penetrate deeper within the tumor due to its small size (∼9 nm), and thereby the pH-sensitive function can be efficiently achieved because the microenvironment in the deeper sites is more acidic. Moreover, the morpholino-terminated PAMAM exhibited longer in vivo circulation time compared to PAMAM and hydroxyl-terminated PAMAM, partly compensating for the disadvantage of short circulation of dendrimers. Furthermore, the morpholino-terminated PAMAM also showed lower cytotoxicity than PAMAM and hydroxyl-terminated PAMAM. [ABSTRACT FROM AUTHOR]