Poly Propylene Imine Dendrimers Research Articles

Formulation and characterization of Pyrazinamide loaded pegylated polypropylene imine dendrimer and its alteration in the pharmacokinetics

Abstract Current study aimed to build a dendrimer for tuberculosis treatment that was loaded with pyrazinamide. The medication pyrazinamide was loaded onto a PEGylated poly(propylene-imine) dendrimer. When it comes to tailored drug delivery, dendrimers are just plain awesome. Investigations into improving the drug loading capacity are being conducted on the free dendrimer, and the synthesised pyrazinamide loaded dendrimer. According to multiple studies, the core Ethylene Diamine (EDA)-PPI dendrimers of the ethylene diamine initiator can be effectively modified by PEGylation. This effort will increase therapeutic value and minimise changes in plasma concentration by carrying out drug transportation at a controlled rate. The therapeutic intervention for tuberculosis patients is enhanced by this feature. A pyrazinamide drug-loaded dendrimer was prepared in separate batches with varying concentrations; the optimal formulation was chosen and given to a rabbit, with the plasma concentration compared to that of the pure drug. Various pharmacokinetic parameters were calculated and the optimized formulation showed excel in the pharmacokinetic parameters.

Spray-drying of PEI-/PPI-based nanoparticles for DNA or siRNA delivery

Spray-drying of nucleic acid-based drugs designed for gene therapy or gene knockdown is associated with many advantages including storage stability and handling as well as the possibility of pulmonary application. The encapsulation of nucleic acids in nanoparticles prior to spray-drying is one strategy for obtaining efficient formulations. This, however, strongly relies on the definition of optimal nanoparticles, excipients and spray-drying conditions. Among polymeric nanoparticles, polyethylenimine (PEI)-based complexes with or without chemical modifications have been described previously as very efficient for gene or oligonucleotide delivery. The tyrosine-modification of linear or branched low molecular weight PEIs, or of polypropylenimine (PPI) dendrimers, has led to high complex stability, improved cell uptake and transfection efficacy as well as high biocompatibility.In this study, we identify optimal spray-drying conditions for PEI-based nanoparticles containing large plasmid DNA or small siRNAs, and further explore the spray-drying of nanoparticles containing chemically modified polymers. Poly(vinyl alcohol) (PVA), but not trehalose or lactose, is particularly well-suited as excipient, retaining or even enhancing transfection efficacies compared to fresh complexes. A big mesh size is critically important as well, while the variation of the spray-drying temperature plays a minor role. Upon spray-drying, microparticles in a ∼ 3.3 – 8.5 µm size range (laser granulometry) are obtained, dependent on the polymers. Upon their release from the spray-dried material, the nanoparticles show increased sizes and markedly altered zeta potentials as compared to their fresh counterparts. This may contribute to their high efficacy that is seen also after prolonged storage of the spray-dried material.We conclude that these spray-dried systems offer a great potential for the preparation of nucleic acid drug storage forms with facile reconstitution, as well as for their direct pulmonary application as dry powder.

Efficient polymeric nanoparticles for RNAi in macrophage reveal complex effects on polarization markers upon knockdown of STAT3/STAT6

Tumor associated macrophages (TAMs) are the most abundant immune cell type in the tissue microenvironment, affecting tumor progression, metastasis and therapeutic response. Different macrophage activation (“polarization”) states can be distinguished: resting (M0; non-activated), pro-inflammatory/anti-tumorigenic (M1) and anti-inflammatory/pro-tumorigenic (M2). When exploring macrophages as targets in novel cancer immunotherapy approaches, TAM repolarization from the M2 into the M1 phenotype is an intriguing strategy to block their pro-tumoral and enhance their anti-tumoral properties.In the context of RNAi-based gene knockdown of M2 promoting genes, major bottlenecks include cellular siRNA delivery and correct intracellular processing. This is particularly true in case of macrophages as a cell type well-known to be notoriously hard-to-transfect. Among polymeric nanocarriers, the cationic polymer polyethylenimine (PEI) is widely explored for delivering nucleic acids. Further advanced nanocarriers are tyrosine-modified polymers based on PEI or polypropylenimine dendrimers (PPI) for highly efficient siRNA delivery in vitro and in vivo.In this paper, we explored a panel of PEI- or PPI-based nanoparticle systems for siRNA-mediated gene knockdown efficacy in macrophages and subsequent TAM repolarization. The tyrosine-modified linear 10 kDa PEI (LP10Y) or branched 5 kDa PEI (P5Y) as well as a tyrosine-modified PPI (PPI-Y) were found most efficient for gene knockdown in macrophage cell lines or primary macrophages, independent of their polarization. Knockdown of STAT6 or STAT3 led to repolarization of M2 macrophages, as indicated by alterations in various M2 and M1 marker levels. This highly specific approach also demonstrated non-redundant functions of STAT3 and STAT6. Importantly, macrophage re-polarization from M2 to M1 upon PPI-Y/siRNA-mediated STAT6 knockdown increased tumor cell phagocytosis in a co-culture model.In conclusion, we identify certain tyrosine-modified PEI- or PPI-based nanoparticles as particularly efficient for macrophage transfection, and the specific, siRNA-mediated STAT6 knockdown as a promising approach for macrophage repolarization and enhancement of their tumor cell suppressive role.

Dendrimers: Patents for Alzheimer's Disease.

Cells and nervous system connections that are crucial for movement, coordination, strength, sensation, and thought are gradually damaged in neurodegenerative illnesses. Amyloid beta (Aβ)- accumulating macromolecules in the brain are the primary cause of the disease's chronic symptoms, according to analysis carried out during the last 20 years. Plaques and clumps of amyloid- build up in the brain, obstructing neuronal signals and destroying neural connections. Tau, a protein that results in the formation of "neurofibrillary tangles" in the brain, another hallmark of neuronal death, has been the focus of a lot of research. Dendrimers Delivery (DDs) is one of the most promising advancements in nanotechnology for biomedical applications, particularly drug delivery. Some of the main categories of dendrimers employed in the successful management of neurodegenerative illnesses are polyamidoamine dendrimers (PAMAM) dendrimers, polypropylenimine dendrimers (PPI), Poly-l-lysine dendrimers (PLL), and carbosilane dendrimers. The tight blood-brain barrier (BBB), which limits the entry of medications or therapeutic agents, makes it difficult to treat central nervous system disorders. Dendrimers have attracted the attention of scientists more than other non-invasive methods of drug delivery across the BBB and improve the uptake of medicines in the brain's target tissues. The major benefits of dendrimers include their adaptability, biocompatibility, ability to load pharmaceuticals into the core and surface, and nanosize. This review has updated the status of the patent and clinical trials literature pertaining to dendrimer use in AD.

Lactoferrin- and Dendrimer-Bearing Gold Nanocages for Stimulus-Free DNA Delivery to Prostate Cancer Cells.

BackgroundThe use of gene therapy to treat prostate cancer is hampered by the lack of effective nanocarriers that can selectively deliver therapeutic genes to cancer cells. To overcome this, we hypothesize that conjugating lactoferrin, a tumor-targeting ligand, and the diaminobutyric polypropylenimine dendrimer into gold nanocages, followed by complexation with a plasmid DNA, would enhance gene expression and anti-proliferation activity in prostate cancer cells without the use of external stimuli.MethodsNovel gold nanocages bearing lactoferrin and conjugated to diaminobutyric polypropylenimine dendrimer (AuNCs-DAB-Lf) were synthesized and characterized. Following complexation with a plasmid DNA, their gene expression, cellular uptake and anti-proliferative efficacies were evaluated on PC-3 prostate cancer cells.ResultsAuNCs-DAB-Lf was able to complex DNA at conjugate: DNA weight ratios 5:1 onwards. Gene expression was at its highest after treatment with AuNCs-DAB-Lf at a weight ratio of 10:1, as a result of a significant increase in DNA uptake mediated by the conjugate at that ratio in PC-3 cells. Consequently, the anti-proliferative activity of AuNCs-DAB-Lf-DNA encoding TNFα was significantly improved by up to 9-fold compared with DAB dendriplex encoding TNFα.ConclusionLactoferrin-bearing dendrimer-conjugated gold nanocages are highly promising gene delivery systems for the treatment of prostate cancer.

Non-viral siRNA transfection of primary mesenchymal stromal cells (MSCs): Assessment of tyrosine-modified PEI and PPI efficacy and biocompatibility

Mesenchymal stromal cells (MSCs) are multipotent cells derived from different sources and able to differentiate into distinct cell lineages. For their possible biomedical application, the “tuning” of MSCs also involves the specific knockdown of defined target genes. A major limitation, however, is the notoriously low transfection efficacy especially of primary MSCs.In this paper, we systemically analyze a large set of tyrosine-modified linear or branched low molecular weight polyethylenimines (PEIs) of different sizes, as well as the tyrosine-modified polypropylenimine dendrimer PPI-G4, for their capacity of non-viral siRNA transfection into umbilical cord-derived MSCs from two different donors. Knockdown efficacies are determined on the molecular level and confirmed in functional assays. Beyond the determination of cell viabilities, acute cytotoxicity, induction of apoptosis/necrosis and mitochondrial membrane alterations are also studied. On the molecular level, caspase activation, ROS induction and genotoxic effects are analyzed.Major differences are observed between the various tyrosine-modified PEIs, with some candidates showing high knockdown efficacy and biocompatibility. PPI-G4-Y dendrimers, however, are identified as most efficient for siRNA transfection into MSCs. PPI-G4-Y/siRNA nanoparticles lead to particularly high gene knockdown, without cytotoxic and genotoxic effects on the cellular and molecular level, and are thus particularly well-suited for the tuning of MSCs.

SYNTHESIS AND CHARACTERIZATION OF LIGAND ANCHORED POLY PROPYLENEIMINEDENDRIMERS FOR THE TREATMENT OF BRAIN GLIOMA

The goal of this study was to develop and characterize Angiopep-2 attached PEGylated Polypropylene imine (PPI) dendrimers for Temozolomide administration to brain gliomas. For surface neutralisation, synthesized PPI dendrimers were conjugated with PEG-2000. PEGylated PPI dendrimers were further coupled with Angiopep-2 (ANG-PEG-PPP) for enhanced medication transport across the blood-brain barrier (BBB) into the area of the brain tumour. Temozolomide loaded ligand-conjugated PPI dendrimers (TAPP) were characterized for size, % drug loading, cumulative drug release, and cell line studies. The drug loading was found to be 57.42±0.8%. In vitro release profile exhibited an early burst release followed by zero-order kinetics (46.8±0.8% in 24 hours). TAPP dendrimers showed improved antiproliferative efficacy against C6 glioma cells in MTT assays and cellular uptake investigations. The ability of TAPP to target cancer cells was examined using an in vitro co-culture model of BCECs and C6 glioma cells. Our findings suggest that Angiopep-2 coupled PEGylated PPI dendrimers could be a suitable nanocarrier for Temozolomide delivery to brain gliomas.

A Comprehensive review on Dendrimers in current advanced Drug delivery

In this particular review, it is been noted that Dendrimers are novel three-dimensional globular nano-polymeric structure; having multiple functional groups on the surface enhances their function. Synonymous terms for dendrimer include arborols and cascade molecules. The importance of dendrimers in a large variety of fields has been detected, where the various types of dendrimers helps in various fields of drug delivery with the different types of dendrimers with the generation. Hence the dendrimer gains more attention from researchers among various nano-materials. Convenient synthesis of the structure makes them as a good nano-material for drug delivery. In recent, dendrimers showed their activity in different drug delivery systems having properties like cancer targeting, anti-bacterial, ocular drug delivery, etc.. The future direction about the dendrimers are been discussed. The present review is focused on types of dendrimers like Polypropylene Imine dendrimer (PPI), Poly(amidoamine) dendrimers (PAMAM), Poly-l-lysine dendrimers, Type of Frechet’s dendrimer, Core-shell tecto dendrimers, Chiral dendrimers, Liquid crystalline dendrimers, Peptide dendrimers, Multiple antigen peptide dendrimers, Glyco-dendrimers, Hybrid dendrimers, Polyester dendrimers in which among these type of dendrimers, the Polypropylene Imine dendrimer (PPI) and Poly(amidoamine) dendrimers are found to be good carriers for various targeting site, Dendrimers are synthesized through various methods like Divergent method, Convergent method, Hyper cores and branched monomer growth method, Double exponential growth method, Click chemistry method, recent advances in dendrimers are used in the Anti-cancer delivery, Anti-bacterial delivery, oral route delivery, pulmonary drug delivery, transdermal drug delivery, ocular delivery, and targeted drug delivery the safety aspects, and future strategies are also been discussed in the below article.

An Exfoliated Graphite-Based Electrochemical Immunosensor on a Dendrimer/Carbon Nanodot Platform for the Detection of Carcinoembryonic Antigen Cancer Biomarker.

An electrochemical immunosensor for the quantification of carcinoembryonic antigen (CEA) using a nanocomposite of polypropylene imine dendrimer (PPI) and carbon nanodots (CNDTs) on an exfoliated graphite electrode (EG) is reported. The carbon nanodots were prepared by pyrolysis of oats. The nanocomposites (PPI and CNDTs) were characterized using X-ray powder diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). The proposed immunosensor was prepared on an exfoliated graphite electrode sequentially by drop coating CNDTs, the electrodeposition of G2-PPI (generation 2 poly (propylene imine) dendrimer), the immobilization of anti-CEA on the modified electrode for 80 min at 35 °C, and dropping of bovine serum albumin (BSA) to minimize non-specific binding sites. Cyclic voltammetry was used to characterize each stage of the fabrication of the immunosensor. The proposed immunosensor detected CEA within a concentration range of 0.005 to 300 ng/mL with a detection limit of 0.00145 ng/mL by using differential pulse voltammetry (DPV). The immunosensor displayed good stability and was also selective in the presence of some interference species such as ascorbic acid, glucose, alpha-fetoprotein, prostate-specific antigen and human immunoglobulin. Furthermore, the fabricated immunosensor was applied in the quantification of CEA in a human serum sample, indicating its potential for real sample analysis.

Study of the effectiveness of the third generation polyamideamine and polypropylene imine dendrimers in removal of reactive blue 19 dye from aqueous solutions

Background: Dye and colored materials cause health risks in water and therefore, must be removed from water supplies and wastewater. The aim of this study was to evaluate the effectiveness of the third generation poly(amidoamine) (PAMAM) and poly (propylene imine) dendrimers (PPI-G3) in the removal of reactive blue 19 (RB19) dye from aqueous solutions and determine the optimum conditions for the removal. Methods: This study was performed in a laboratory and batch scale. In this study, synthetic wastewater was examined with three different concentrations of RB19 (25, 50, and 100 mg/L), different pHs (3, 7, and 10), various amounts of dendrimer (0.4, 0.8, 1.2, and 1.6 g/L), and at different times (15, 30, and 60 minutes) during the adsorption process. The remaining amount of dye was measured by spectrophotometer at 592 nm wavelength. Langmuir and Freundlich isotherms were also tested. Results: The results showed that by increasing the reaction time and adsorbent dosage, the rate of dye removal increased while by increasing the initial dye concentration and pH, the dye removal efficiency was significantly decreased. In this study, with increase of pH from 3 to 10, dye removal efficiency at a concentration of 25 mg/L, decreased from 72% to 20% and 88% to 17% by PAMAM and PPI dendrimers, respectively. Excel software was used for data analysis. Conclusion: Both adsorbents had a good dye removal efficiency, but PPI dendrimer was more effective in removing RB19. Adsorption data followed the Langmuir isotherm.

PEGylation of polypropylenimine dendrimers: effects on cytotoxicity, DNA condensation, gene delivery and expression in cancer cells

Diaminobutyric polypropylenimine (DAB) dendrimers have been shown to be highly efficient non-viral gene delivery systems for cancer therapy. However, their cytotoxicity currently limits their applications. To overcome this issue, PEGylation of DAB dendrimer, using various PEG molecular weights and dendrimer generations, has been attempted to decrease the cytotoxicity and enhance the DNA condensation, size and zeta potential, cellular uptake and transfection efficacy of these dendriplexes. Among all the PEGylated dendrimers synthesized, generation 3- and generation 4-DAB conjugated to low molecular weight PEG (2 kDa) at a dendrimer: DNA ratio of 20:1 and 10:1 resulted in an increase in gene expression on almost all tested cancer cells lines (by up to 3.2-fold compared to unmodified dendrimer in A431 cells). The highest level of β-galactosidase gene expression (10.07 × 10−3 ± 0.09 × 10−3 U/mL) was obtained following treatment of B16F10-Luc cells with G4-dendrimer PEGylated with PEG2K at a dendrimer: DNA ratio of 20:1. These delivery systems significantly decreased cytotoxicity on B16F10-Luc cells, by more than 3.4-fold compared to unmodified dendrimer. PEGylated generations 3- and 4-DAB dendrimers are therefore promising gene delivery systems for cancer therapy, combining low cytotoxicity and high transfection efficacy.

Mesoporous silica nanoparticles decorated with polycationic dendrimers for infection treatment

This work aims to provide an effective and novel solution for the treatment of infection by using nanovehicles loaded with antibiotics capable of penetrating the bacterial wall, thus increasing the antimicrobial effectiveness. These nanosystems, named “nanoantibiotics”, are composed of mesoporous silica nanoparticles (MSNs), which act as nanocarriers of an antimicrobial agent (levofloxacin, LEVO) localized inside the mesopores. To provide the nanosystem of bacterial membrane interaction capability, a polycationic dendrimer, concretely the poly(propyleneimine) dendrimer of third generation (G3), was covalently grafted to the external surface of the LEVO-loaded MSNs. After physicochemical characterization of this nanoantibiotic, the release kinetics of LEVO and the antimicrobial efficacy of each released dosage were evaluated. Besides, internalization studies of the MSNs functionalized with the G3 dendrimer were carried out, showing a high penetrability throughout Gram-negative bacterial membranes. This work evidences that the synergistic combination of polycationic dendrimers as bacterial membrane permeabilization agents with LEVO-loaded MSNs triggers an efficient antimicrobial effect on Gram-negative bacterial biofilm. These positive results open up very promising expectations for their potential application in new infection therapies. Statement of SignificanceSeeking new alternatives to current available treatments of bacterial infections represents a great challenge in nanomedicine. This work reports the design and optimization of a new class of antimicrobial agent, named “nanoantibiotic”, based on mesoporous silica nanoparticles (MSNs) decorated with polypropyleneimine dendrimers of third generation (G3) and loaded with levofloxacin (LEVO) antibiotic. The covalently grafting of these G3 dendrimers to MSNs allows an effective internalization in Gram-negative bacteria. Furthermore, the LEVO loaded into the mesoporous cavities is released in a sustained manner at effective antimicrobial dosages. The novelty and originality of this manuscript relies on proving that the synergistic combination of bacteria-targeting and antimicrobial agents into a unique nanosystem provokes a remarkable antimicrobial effect against bacterial biofilm.

Regression of prostate tumors after intravenous administration of lactoferrin-bearing polypropylenimine dendriplexes encoding TNF-α, TRAIL, and interleukin-12

The possibility of using gene therapy for the treatment of prostate cancer is limited by the lack of intravenously administered delivery systems able to safely and selectively deliver therapeutic genes to tumors. Given that lactoferrin (Lf) receptors are overexpressed on prostate cancer cells, we hypothesized that the conjugation of Lf to generation 3-diaminobutyric polypropylenimine dendrimer would improve its transfection and therapeutic efficacy in prostate cancer cells. In this study, we demonstrated that the intravenous administration of Lf-bearing DAB dendriplexes encoding TNFα resulted in the complete suppression of 70% of PC-3 and 50% of DU145 tumors over one month. Treatment with DAB-Lf dendriplex encoding TRAIL led to tumor suppression of 40% of PC-3 tumors and 20% of DU145 tumors. The treatment was well tolerated by the animals. Lf-bearing generation 3-polypropylenimine dendrimer is therefore a highly promising delivery system for non-viral gene therapy of prostate cancer.

Improved Electro-optical Performance of OLEDs Using PdCo Alloy Nanoparticles Supported on Polypropylenimine Dendrimer–Grafted Graphene

We fabricated organic light emitting diodes (OLEDs) with PdCo alloy nanoparticles supported on polypropylenimine dendrimer–grafted graphene (PdCo/PPI–g-G) that was doped at different concentrations (0, 0.02, 0.03, 0.06 and 2 wt%) in a poly(3,4-ethylene dioxythiophene): polystyrene sulfonic acid (PEDOT:PSS) as a host layer. PdCo PPI–g-G and PEDOT:PSS were studied as hole injection layers in OLEDs. The efficiency of hole injection from the anode is strongly dependent on the concentration of the PdCo/PPI–g-G. While a graphene oxide and pure PEDOT:PSS layer leads to higher driving voltage and decreased luminescence efficiency. PdCo/PPI–g-G of 0.02 wt% noticeably enhanced the hole injection and resulted in lower turn-on voltage, increased luminance, and current efficiencies. The 0.02 wt% PdCo/PPI–g-G based device has also a luminance of 3705 cd/m2 and maximum efficiency of 1.9 cd/A at 13 V which are the highest values among other PdCo/ PPI–g-G based devices.

The relationship between odour intensity and antibacterial durability of encapsulated thyme essential oil by PPI dendrimer on cotton fabrics

The relationship between odour intensity and antibacterial properties of thyme essential oil (EO) in the presence of second generation of polypropylene Imine (PPI-G2) dendrimer as a control release agent was investigated. Odour release of thyme EO from treated fabric was measured via an electronic nose (e-nose). Staphylococcus Aureus and Escherichia Coli were considered as target bacteria to evaluate the antibacterial activity of treated fabrics. Results reveal that PPI-G2 dendrimer has strong effect on antibacterial retention under washing process and exposing to the free air. Furthermore, FTIR results show the reaction between PP-G2 and thyme EO on cotton fabrics. E-nose data also indicated that PPI-G2 provided controlled release of odour from treated fabric since the rate of odour release of samples with the dendrimer was much slower than samples without the dendrimer. It was found that e-nose results correlated with antibacterial activity with correlation coefficient of r = 0.988 for samples without PPI-G2.

Targeted nanodiamonds for identification of subcellular protein assemblies in mammalian cells.

Transmission electron microscopy (TEM) can be used to successfully determine the structures of proteins. However, such studies are typically done ex situ after extraction of the protein from the cellular environment. Here we describe an application for nanodiamonds as targeted intensity contrast labels in biological TEM, using the nuclear pore complex (NPC) as a model macroassembly. We demonstrate that delivery of antibody-conjugated nanodiamonds to live mammalian cells using maltotriose-conjugated polypropylenimine dendrimers results in efficient localization of nanodiamonds to the intended cellular target. We further identify signatures of nanodiamonds under TEM that allow for unambiguous identification of individual nanodiamonds from a resin-embedded, OsO4-stained environment. This is the first demonstration of nanodiamonds as labels for nanoscale TEM-based identification of subcellular protein assemblies. These results, combined with the unique fluorescence properties and biocompatibility of nanodiamonds, represent an important step toward the use of nanodiamonds as markers for correlated optical/electron bioimaging.

Synthesis of Ni–W aromatic hydrocarbon hydrogenation catalysts by the ex situ and in situ decomposition of a precursor based on a dendrimer network

A Ni–W precursor supported on a dendrimer-containing crosslinked polymer (42 wt % of a third-generation polypropylenimine dendrimer) has been first synthesized. The precursor has been subjected to the ex situ and in situ decomposition in a hydrocarbon feedstock to prepare an unsupported Ni–W sulfide catalyst. The activity of the resulting catalyst in the hydrogenation of aromatic hydrocarbons has been studied using the example of naphthalene. The process has been conducted in an autoclave-type reactor in a temperature range of 350–400°C at a hydrogen pressure of 5.0 MPa. It has been shown that the in situ synthesis of a Ni–W catalyst leads to the formation of particles exhibiting higher activity in the hydrogenation of naphthalene. The in situ synthesized Ni–W particles have been characterized by TEM and XPS.

PLLA scaffolds surface-engineered via poly (propylene imine) dendrimers for improvement on its biocompatibility/controlled pH biodegradability

Novel aminolyzed Poly (L) Lactic Acid (PLLA) films and electrospun nanofibrous scaffolds were fabricated and characterized as potential substrates for tissue engineering. The second generation polypropylene imine dendrimer (PPI-G2) was used as the aminolysis agent to functionalize the inert surface of PLLA substrates directly without any pre-modification process. The effect of the solvent type, G2 concentration, reaction temperature and time were studied by following weight reduction percentage, FTIR and contact angle measurements due to determined optimum conditions. In addition, the modified scaffolds abbreviated by PLLA/G2 were analyzed using mechanical properties, SEM images and dye assays as host-guest modeling. The results indicate that under the 0.5 (wt.%) G2 concentration, ethanol as the solvent, room temperature and 4h of treatment, the optimum conditions were obtained. It was shown that the hydrophilic properties of PLLA/G2 were greatly enhanced. Also, pH value analysis revealed that after 4 weeks, the biodegradation of PLLA caused massive immune cells infusion and inflammation in the medium through increasing the acidic rate by secretion the lactic acid, whereas the PLLA/G2 scaffolds greatly reduced and stabilize the acidic rate through aminolysis reaction. Finally, promoted cell adhesion and viability underlined the favorable properties of PLLA/G2 scaffolds as a biodegradable biomaterial for biomedical implants.

Alkyl cross-linked low molecular weight polypropyleneimine dendrimers as efficient gene delivery vectors.

In recent years, polypropyleneimine (PPI) dendrimers have attracted great interest as non-viral gene delivery systems because of their attractive features including highly branched architecture with number of reactive end groups. However, without being structurally modified, they are not efficient gene carriers. In the present study, generation 2 and 3 (G2 and G3) of PPI dendrimers were conjugated with alkylcarboxylate groups as linker to enhance the transfection efficiency while maintaining their low cell toxicity. First, 10-bromodecanoic acid was covalently attached to all available surface primary amines of PPI G2 and G3 to increase their lipophilicity. In the subsequent step, PPIs were conjugated to the alkylcarboxylate groups of alkylcarboxylate-PPI derivatives to increase the number of surface primary amines. Physicochemical properties of modified PPIs were determined. Transfection experiments (using both luciferase and green fluorescent protein (GFP)- expressing plasmids) and cytotoxicity assay were performed to evaluate the efficiency of the final derivatives. Fabricated vectors condensed DNA effectively so that polyplexes with appropriate size (below 155 nm) and positive surface charge were constructed. Cross-linked low molecular weight PPIs (G2 or G3) with decanoate linkage increased transfection efficiency significantly while maintaining the low cytotoxicity. PPI G2 derivative exhibited increased buffering capacity which is believed to be responsible for better proton sponge mechanism leading to higher transfection efficiency. Our results indicated that oligomerization of low molecular weight PPI (PPI G2-alkyl-PPI G2 conjugate) could be an approach to increase the transfection efficiency and to lower the cytotoxicity of low molecular weight polycations.

Preparation of long-lasting fragrant worsted fabrics using polypropylene-imine (PPI) dendrimer

Purpose The production of long-lasting fragrant semi-worsted fabrics using dendritic compounds as one of the nano size materials is concerned. Also quantitative assessments of the odour intensity of the fragrant fabrics using an electronic-nose (E-nose) are made. The paper aims to discuss these issues. Design/methodology/approach The semi-worsted fabrics were perfumed using the second generation of polypropylene-imine (PPI) dendrimer as a host molecules. The ginseng and rosewater fragrances as guest molecules were applied into the PPI dendrimer to produce long-lasting fragrant fabrics. The odour intensity as well as long-lasting properties of the fragrant fabrics perfumed recently and the other sample perfumed one year ago were evaluated via E-nose fabricated in our laboratory. Physical properties of the fragrant fabrics were compared to the non-fragrant ones. Findings The interaction between ginseng and rosewater fragrances with the second generation of PPI dendrimer into the semi-worsted fabrics made a long-lasting fragrant fabrics without considerable impacts on bending length, air permeability and wrinkle recovery angles based on statistical analysis. However, the effects of making fragrant fabrics on the increasing weight are significant. In addition, the E-nose was successfully used to monitor the release of ginseng and rosewater fragrance from the fabrics by the response patterns of a temperature-modulated chemo-resistive gas sensor. E-nose analysis showed that the aroma intensity released from the old fragrant semi-worsted fabrics has no obvious diversity from that of new fragrant fabrics. Originality/value The findings suggest that the semi-worsted fabrics perfumed with dendritic materials revealed excellent sustained release property.