Fatty Acid–RGD Peptide Amphiphile Micelles as Potential Paclitaxel Delivery Carriers to αvβ3Integrin Overexpressing Tumors

Purpose

To design and synthesize fatty acid-RGD peptide amphiphiles with ADA linker for their potential delivery of hydrophobic drugs like paclitaxel targeted to α_vβ₃ integrin overexpressing tumors.

Methods

Four amphiphiles - C16 or C18 fatty acid–RGD peptide and ADA linker were designed and synthesized. CMC, size and zeta potential of the amphiphiles were determined. FITC loaded micelles uptake into A2058 melanoma cells was investigated at 4°C and 37°C using confocal microscopy. Paclitaxel was loaded into micelles, their encapsulation efficiency and cytotoxicity of micelles was evaluated. The stability of the micelles was determined using FRET method.

Results

Mass, ¹H NMR and HPLC analysis confirmed the formation of amphiphiles and their purity. Among the amphiphiles, C18-(ADA)₂-RGD amphiphile exhibited lowest CMC (9.00?±?1.73?μM) and its micelles had suitable size (194.63?±?44.86?nm) and zeta potential (0.27?±?1.96?mV) for targeting. The cellular uptake of the micelles was temperature dependent and the micelles were stable. The IC50 of paclitaxel loaded in micelles decreased 50% in α_vβ₃ integrin overexpressing cells and showed a 4 fold increase in normal cells when compared to free paclitaxel.

Conclusion

Amphiphiles of fatty acids–ADA-RGD were synthesized. These amphiphiles formed stable micelles and were effective as targeted delivery carriers to α_vβ₃ integrin overexpressing tumors.     

Gene transfer with three amphiphilic glycol chitosans--the degree of polymerisation is the main controller of transfection efficiency

A number of studies have examined the possibility of delivering genes for the treatment of genetic diseases using various polymers and lipids. We have previously demonstrated the gene transfer ability of amphiphilic polymers (a soluble amine polymer covalently bound to lipid pendant groups). In the current communication we explore the gene transfer activity of amphiphilic glycol chitosans. Glycol chitosan was acid depolymerised to give polymers of various molecular weights. Palmitoyl or hexadecyl and in some cases additional N-methyl quaternary ammonium groups were attached to the polymers. DNA binding was studied by measuring the reduced fluorescence of ethidium bromide and the polyplex particle size and zeta potential. Biological characterisation of the polyplexes involved haemolysis, cytotoxicity and gene transfer assays. For the 22 polymers tested, DNA binding was optimum at a nitrogen to phosphate ratio of 2:1 and above. Polyplexes were 200-500 nm in diameter with a neutral or positive zeta potential. The haemolytic activity of the N-methyl polymers was studied and no haemolysis was detected up to a concentration of 10 mg ml-1. Cytotoxicity studies showed that the biocompatibility of glycol chitosan was adversely affected by a combination of a palmitoyl group and depolymerisation and that biocompatibility was subsequently restored with the introduction of N-methyl groups. In vitro transfection efficiency superior to the cationic lipid formulation N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium methyl sulphate (DOTAP) was seen with depolymerised glycol chitosan in the A431 cell line only and with the depolymerised N-methyl quaternary ammonium amphiphilic derivatives in both the A431 and A549 cell lines. Degree of polymerisation (DP) was the most important controller of transfection efficiency and transfection resided within polymers with a DP of 73-171. High DP polymers diminished DNA-cell association, the first step in the cellular gene transfer process, thus apparently diminishing cell uptake. In vivo transfection with the N-methyl quaternary ammonium amphiphile was best at a DP of 86 and this glycol chitosan amphiphile gave superior liver and heart gene expression levels when compared to both Exgen 500 (linear polyethylenimine) and Superfect (a polyamidoamine dendrimer).     

Gene Transfer with Three Amphiphilic Glycol Chitosans—the Degree of Polymerisation is the Main Controller of Transfection Efficiency

A number of studies have examined the possibility of delivering genes for the treatment of genetic diseases using various polymers and lipids. We have previously demonstrated the gene transfer ability of amphiphilic polymers (a soluble amine polymer covalently bound to lipid pendant groups). In the current communication we explore the gene transfer activity of amphiphilic glycol chitosans. Glycol chitosan was acid depolymerised to give polymers of various molecular weights. Palmitoyl or hexadecyl and in some cases additional N-methyl quaternary ammonium groups were attached to the polymers. DNA binding was studied by measuring the reduced fluorescence of ethidium bromide and the polyplex particle size and zeta potential. Biological characterisation of the polyplexes involved haemolysis, cytotoxicity and gene transfer assays. For the 22 polymers tested, DNA binding was optimum at a nitrogen to phosphate ratio of 2:1 and above. Polyplexes were 200–500 nm in diameter with a neutral or positive zeta potential. The haemolytic activity of the N-methyl polymers was studied and no haemolysis was detected up to a concentration of 10 mg ml^?1. Cytotoxicity studies showed that the biocompatibility of glycol chitosan was adversely affected by a combination of a palmitoyl group and depolymerisation and that biocompatibility was subsequently restored with the introduction of N-methyl groups. In vitro transfection efficiency superior to the cationic lipid formulation N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium methyl sulphate (DOTAP) was seen with depolymerised glycol chitosan in the A431 cell line only and with the depolymerised N-methyl quaternary ammonium amphiphilic derivatives in both the A431 and A549 cell lines. Degree of polymerisation (DP) was the most important controller of transfection efficiency and transfection resided within polymers with a DP of 73–171. High DP polymers diminished DNA–cell association, the first step in the cellular gene transfer process, thus apparently diminishing cell uptake. In vivo transfection with the N-methyl quaternary ammonium amphiphile was best at a DP of 86 and this glycol chitosan amphiphile gave superior liver and heart gene expression levels when compared to both Exgen 500 (linear polyethylenimine) and Superfect (a polyamidoamine dendrimer).     

Effect of hydroxypropylmethylcellulose (HPMC) on the release profiles and bioavailability of a poorly water-soluble drug from tablets prepared using macrogol and HPMC

The aim of the present study was to investigate the effect of hydroxypropylmethylcellulose (HPMC-2208), used as an excipient for controlled release of drug, on the release profiles and bioavailability of the poorly water-soluble nifedipine (NP) from a tablet prepared using macrogol 6000 (PEG) and HPMC. The crushing tolerance of the NP tablet prepared using PEG and HPMC (NP-PEG-HPMC tablet) was markedly increased with increasing compression force used during the preparation from 20 to 200 MPa. The values reached their maximal levels (approximately 13 kg for the NP-PEG-HPMC tablet and 8 kg for the PEG tablet) at the compression force of 100 MPa. Although NP is a poorly water-soluble drug, it was rapidly dissolved from the NP-PEG tablet (without HPMC) due to the improvement of its dissolution rate in the presence of PEG. NP dissolution was complete at the latest within 1 h. On the other hand, dissolution of NP from the NP-PEG-HPMC tablet was significantly delayed with an increase in the concentration of HPMC in the tablet. The dissolution of NP from the NP-PEG-HPMC tablet containing 50% HPMC-2208 was markedly delayed as the viscosity of HPMC also increased. Interestingly, the same peak plasma NP concentration (C(max)) and the area under the plasma NP concentration-time curve (AUC(0-10)) were observed for both the NP-PEG tablet and NP-PEG-HPMC tablets, however, the time to C(max) (t(max)) for the NP-PEG-HPMC tablet was significantly higher when the NP-PEG-HPMC tablet was orally administered to rabbits. We describe here a preparation method of a new sustained-release NP-PEG-HPMC tablet using a mixture of NP-PEG granules (prepared with PEG) and HPMC.     

转铁蛋白修饰的载基因前阳离子脂质体制备及其表达研究

本文制备、优化转铁蛋白修饰的前阳离子脂质体，并研究其相关性质。通过薄膜分散膜挤压法制备空白前阳离子脂质体；以鱼精蛋白缩合质粒DNA与空白前阳离子脂质体作用形成载基因前阳离子脂质体(PLPD)；转铁蛋白(transferrin，Tf)再与PLPD作用形成转铁蛋白修饰的载基因前阳离子脂质体(Tf-PLPD)；中心组合设计优化制备工艺；以lacZ为报告基因转染人肝癌细胞株HepG2；测定形态、粒径、电位和转染效率。结果显示，PLPD形态近似于球体，平均粒径为(228.9±8.0) nm，多分散指数为0.122±0.020(n=3)；zeta电位为(-25.08±2.50) mV(n=3)，转染效率(12.18±3.80) mU·mg^-1(protein)。Tf-PLPD平均粒径为(240±12) nm，多分散指数为0.150±0.030(n=3)；zeta电位为(-24.10±2.50) mV(n=3)；转染效率(24.26±2.60) mU·mg^-1(protein)是裸质粒的20倍；实验结果也表明血清的存在不影响PLPD和Tf-PLPD的转染效率；PLPD和Tf-PLPD小于阳离子脂质体LPD对人肝癌细胞HepG2，SMMC7721和张氏正常肝细胞3种细胞株的毒性。由此可见，转铁蛋白修饰的前阳离子脂质体作为基因转运的非病毒载体具有良好的应用前景。     

A new biodegradable poly-amino acid: alpha,beta-poly[(N-hydroxypropyl/aminoethyl)-DL-aspartamide-co-L-lysine], a potential nonviral vector for gene delivery

A new class of biodegradable poly-amino acid, alpha,beta-poly[(N-hydroxypropyl/aminoethyl)-DL-Aspartamide-co-L-Lysine] (PHAAL), was synthesized by ring-opening of poly[succinimide-co-lysine](PSL) with n-propanolamine and ethylene diamine after thermal copolycondensation of DL-Aspartic acid and L-lysine under reduced pressure. Different ratio feeds of PSL were obtained and characterized by 1H-NMR, Fourier transformed infrared spectroscopy, X-ray, thermogravimetric analysis and gel permeation chromatography experiments. As one of the polycationic materials, performed for gene delivery carrier, the PHAAL degradation experiment was carried out in PBS (10 mM, pH =7.4) and enzyme (papain, trypsine 1 mg/ml, 37 +/- 0.1 degree C) solution. PHAAL had lower cytotoxicity than polyethylenimine (25KDa) and poly-L-Lysine (30 KDa), in Hela, E.C.V.-304, Bcap 37 cell lines. Particle size and zeta, potential of PHAAL/DNA complexes were measured. Sizes ranged from 300-500 nm and zeta potentials were at -20 to 2,5 mV. The condensation ability of PHAAL for DNA was evaluated by agarose gel electrophoresis. The PHAAL could completely neutralize DNA at N/P ratio (w/w) 150:1.     

Design and evaluation of polyamidoamine dendrimer conjugate with PEG, α-cyclodextrin and lactose as a novel hepatocyte-selective gene carrier in vitro and in vivo

Abstract

To develop a novel hepatocyte-selective gene carrier, we prepared polyamidoamine starburst dendrimer (generation 3, G3) conjugates with three functional molecules, i.e. α-cyclodextrin, polyethylene glycol (PEG, molecular weight?=?2170) and lactose (PEG-LαCs), and evaluated gene delivery efficiency of these conjugates in vitro and in vivo. PEG-LαC (G3, degrees of substitution of the PEG moiety (DSP) 2.1) showed higher gene transfer activity than other PEG-LαCs (G3, DSP4.0, 6.2) in HepG2 cells, expressing asialoglycoprotein receptor, and the activity decreased in HeLa cells, non-expressing the receptor and in the presence of asialofetuin. High gene transfer activity of PEG-LαC (G3, DSP2.1) was retained even in the presence of 50% serum, although the activity of α-cyclodextrin/lactosylated dendrimer (G3) conjugate (Lac-α-CDE (G3)), which is lacking a PEG moiety, was severely decreased in the presence of 20% serum. PEG-LαC (G3, DSP2.1) provided negligible cytotoxicity up to a charge ratio of 50 (carrier/pDNA) in HepG2 cells and less acute organ toxicity. PEG-LαC (G3, DSP2.1) showed selective gene transfer activity to hepatic parenchymal cells rather than hepatic non-parenchymal cells. These results suggest that PEG-LαC (G3, DSP2.1) is useful as a hepatocyte-selective gene carrier in vitro and in vivo.     

Anticancer drug delivery of PEG based micelles with small lipophilic moieties

Herein, we reported a new type of self-assembly micelles based on amphiphilic polymers of cinnamate and coumarin derivatives modified PEG for drug delivery applications. Lipophilic cinnamic acid (CIN) and 7-carboxyl methoxycoumarin (COU) were immobilized on the terminal groups of poly(ethylene glycol) (PEG) to prepare amphiphiles. The amphiphiles self-assembled into micelles. The amphiphiles and micelles were characterized by ¹H NMR, FT-IR, DLS and TEM. Doxorubicin (DOX) was used as a model drug to investigate the lipophilic moieties effects on the drug release behaviors. The DOX loaded micelles were incubated with HepG2 liver cancer cells to study the in vitro anticancer activities. The results showed that DOX could be encapsulated in the micelles efficiently. The mean diameter of the drug loaded micelles was around 100 nm. Drug release profile revealed that the release rate of DOX loaded COU-PEG-COU micelles was significantly slower than that of CIN-PEG-CIN micelles. The DOX loaded micelles could be internalized in HepG2 cells. Both CLSM and flow cytometry results showed that the DOX loaded CIN-PEG-CIN micelles exhibited better anticancer efficacy.     

Poly(ester amine) constructed from polyethylenimine and pluronic for gene delivery in vitro and in vivo

A series of poly (ester amines) (PEAs) constructed from low molecular weight polyethyleneimine (LPEI, Mw: 0.8k, 1.2k Da) and Pluronic (different molecular weight (Mw) and hydrophilic-lipophilic-balance (HLB)) components were synthesized, and evaluated in vitro and in vivo as gene delivery carriers. Most PEA polymers were able to bind and condense plasmid DNA effectively into particles of approximately 150?nm in solution at the polymer/DNA ratio of 5 and above. Transfection efficiency of the PEA polymers depends on particle size of the polymer/DNA complex, molecular weight and HLB of the Pluronics and the size of PEI within PEA composition, as well as the cell type. Significant improvement in gene delivery efficacy was achieved with PEA01/04/05 composed of Pluronic size (Mw: 3000–5000?Da), and HLB (12–18) in CHO, C2C12 and HSkM cell lines; and the effective transfection was reflected with PEA 01/04/07 composed of Pluronics with size (2000–5000?Da) and HLB (12–23) in mdx mice. The best formulation for pDNA delivery was obtained with PEA 01 producing transgene expression efficiency 5, 19-folds of that of PEI 25k in vitro and in vivo, respectively. These results potent some of these PEA polymers as attractive vehicles for gene or oligonucleotide delivery.     

Imidazolyl-PEI modified nanoparticles for enhanced gene delivery

The derivatives of polyethylenimine (PEI 25 and 750kDa) were synthesized by partially substituting their amino groups with imidazolyl moieties. The series of imidazolyl-PEIs thus obtained were cross-linked with polyethylene glycol (PEG) to get imidazolyl-PEI-PEG nanoparticles (IPP). The component of hydrophobicity was introduced by grafting the lauryl groups in the maximal substituted IPP nanoparticles (IPPL). The nanoparticles were characterized with respect to DNA interaction, hydrodynamic diameter, zeta potential, in vitro cytotoxicity and transfection efficiency on model cell lines. The IPP and IPPL nanoparticles formed a loose complex with DNA compared to the corresponding native PEI, leading to more efficient unpackaging of DNA. The DNA loading capacity of IPP and IPPL nanoparticles was also lower compared to PEI. The imidazolyl substitution improved the gene delivery efficiency of PEI (750kDa) by nine- to ten-fold and PEI (25kDa) by three- to four-fold. At maximum transfection efficiency, the zeta potential of nanoparticles was positive after forming a complex with DNA. The maximum level of reporter gene expression was mediated by IPPL nanoparticles in both the series. The cytotoxicity, another pertinent problem with cationic polymers, was also negligible in case of IPP and IPPL nanoparticles.     

葡聚糖-精胺阳离子聚合物基因载体体外基因转染的研究

本文研究了葡聚糖-精胺阳离子聚合物(DSP)基因载体的性能及其对体外细胞基因的转染效率。氧化葡聚糖与精胺通过还原胺化法反应制得DSP，所得DSP与质粒pEGFP通过静电吸附形成复合物；当DSP/DNA质量比在4∶1至20∶1，能形成稳定的复合物，复合物粒径为162.6～187.9 nm，zeta电位则从+8.45 mV增至+39.6 mV；DSP能有效保护DNA不受核酸酶I降解，同时在一定pH范围内载体具有较强的缓冲能力；复合物在质量比为8∶1时对SMMC-7721肝癌细胞、BHK-21细胞的转染率分别达到最高，其效果均与Lipofectamine 2000相当。该研究表明葡聚糖-精胺阳离子聚合物是一种高效的基因载体。     

Spermine grafted galactosylated chitosan for improved nanoparticle mediated gene delivery

Despite multitude of beneficial features, chitosan has poor water solubility and transfection ability which affect its gene delivery efficacy. The two features are improved when certain chemical modifications are incorporated into the chitosan parent backbone. This strategy is adopted here, by coupling galactose and spermine into the chitosan backbone. The conjugation was determined with FTIR and (1)H NMR and nanoparticle morphology was assessed by TEM and AFM techniques. Particle size, zeta potential, buffering capacity and DNA binding ability gave encouraging result of enhanced solubility and stability. In vitro studies of GCSM in HepG2 cell lines displayed low cytotoxicity and improved transfection. We also identified the preference of receptor mediated internalization for nanoparticles cellular uptake by treating with cellular uptake inhibitors. The results evidently led us to comprehend that galactosylated chitosan-g-spermine could be considered as a promising chitosan derivative for conducting nanoparticle mediated gene delivery.     

Characterization and stability of solid dispersions based on PEG/polymer blends

Solid dispersions were prepared by a melting method from the water-insoluble model drugs carbamazepine and nifedipine and polyethylene glycol 1500 (PEG 1500) or 1:1 mixtures of PEG 1500 and the polymers polyvinylpyrrolidone (PVP 30, PVP 12), polyvinylpyrrolidone-co-vinylacetate (PVPVA) and Eudragit EPO (Eudragit) in order to combine advantages of the different carrier polymers (recrystallization inhibition, processability and stability). The solid dispersions were characterized by dissolution, powder X-ray diffractometry and microscopy directly after preparation and after storage for 3 and 6 months at 25 °C/0% relative humidity (RH) or 3 months at 40 °C/75% RH. More than 80% drugs were released from all solid dispersions within 20 min. The dissolution rate of carbamazepine decreased in the order of PEG 1500 > PEG 1500/Eudragit > PEG 1500/PVP 30 > PEG 1500/PVPVA > PEG 1500/PVP 12. The dissolution rank order was not directly correlated to the amorphous/crystalline state of the drugs, but rather to the properties of the PEG 1500/polymer compositions. Nifedipine was released in the order of PEG 1500 > PEG 1500/PVPVA > PEG 1500/PVP 30 > PEG 1500/PVP 12 > PEG 1500/Eudragit. Amorphous nifedipine was present in all PEG 1500/polymer dispersions except in pure PEG 1500 solid dispersion. The significant increase in dissolution rate of PEG 1500 solid dispersions was due to the reduced crystallinity of the drug and the excellent solubilisation properties of PEG 1500. After 6 months storage at 25 °C/0% RH, the solid dispersions released both drugs in the order PEG 1500/PVPVA > PEG 1500/PVP 30 > PEG 1500/PVP 12 > PEG 1500/Eudragit > PEG 1500. The stabilized amorphous state of the drug resulted in stable dissolution profiles of PEG 1500/PVPVA, PEG 1500/PVP 30 and PEG 1500/PVP 12 when compared to the PEG 1500 solid dispersions, which contained a higher amount of crystalline drug. The solid dispersions with PEG 1500/PVPVA or PEG 1500/PVP stored for 3 months at 40 °C/75% RH showed phase separation due to the hygroscopic properties of the polymers. The influence of 10% (w/w) of the solubilisers polyoxyl 40 hydrogenated castor oil (Cremophor), macrogol-15-hydroxystearate (Solutol) and fatty alcohol alkoxylate (Pluronic) on the dissolution rate and the physical state of the drug was significant.     

Preparation and gene delivery of alkaline amino acids-based cationic liposomes

Cationic lipids 1, 2, and 3, based on hydrophobic cholesterol linked to L-lysine, L-histidine or L-arginine, respectively, were designed and tested as gene delivery vectors. Physicochemical and biological properties of all liposomes and lipoplexes were evaluated, including lipid-DNA interactions, size, morphology, zeta potential, acid-base buffering capability, protection of DNA from DNase I digestion, and cytotoxity. The efficiency of luciferase gene transfection of lipoplexes 1-3 was compared with that of commercial dioleoyl-trimethylammonium propane (DOTAP) and polyethyleneimine (PEI) in 293T cells and HepG2 cells with or without poly(ethylene glycol) PEG stabilizer. The complexation and protection of DNA of liposome 3 was the strongest among the three liposomes. The efficiency of gene transfection of liposomes 1-3 was two-to threefold higher than that of PEI and/or DOTAP in 293T cells. Liposomes 1 and 3 in PEG as stabilizer showed sixfold higher transfection efficiency than that of PEI and/or DOTAP, whereas liposome 2 showed very low transfection efficiency. In HepG2 cells, the transfection efficiency of all the cationic liposomes was much lower than that of DOTAP. In conclusion, lipids 1-3 were efficient and non-toxic gene vectors; the headgroup of cationic lipids and the stabilizer of liposome formulation had an important influence on gene transfection.     

Synthesis and characterization of RGD-fatty acid amphiphilic micelles as targeted delivery carriers for anticancer agents

Novel amphiphilic conjugates consisting of an Arg-Gly-Asp (RGD) peptide binding motif and aliphatic fatty acids of varying chain length (C10-C18) were synthesized and evaluated for their ability to form micelles and bind specifically to alphaVbeta3 integrin over-expressing tumor cells. The aphilphiles were characterized by IR, proton NMR and mass spectrometry. The size and zeta potential of the resultant micelles were ranged from 178 to 450 nm and - 13.5 to 39.6 mV, respectively. The critical micellar concentration (CMC), drug loading efficiency and tumor cell binding of these amphiphiles were determined. The CMC values, determined by pyrene fluorescent probe method, ranged from 0.02 to 0.12 mM for C14-RGD, C16-RGD and C18-RGD. The C18-RGD micelles with lowest CMC were found to increase the solubility of taxol, a model anticancer drug, by 87%. C18-RGD amphiphiles also exhibited significantly higher (12.1 +/- 1.14%, P < 0.05) binding to alphaVbeta3 integrin over-expressing human breast cancer cells (HTB-129) when compared to normal human epidermal keratinocyte (NHEK) cells (6.68 +/- 0.34). The results from this study demonstrated the feasibility of designing RGD-fatty acid amphiphiles as micellar drug delivery carriers to target to cancer cells.     

The establishment of an up-scaled micro-mixer method allows the standardized and reproducible preparation of well-defined plasmid/LPEI polyplexes

Polyplexes based on linear polyethylenimine (LPEI) and plasmid DNA are known as efficient non-viral gene delivery systems. However, the requirement for freshly prepared complexes prior to administration due to their instability in aqueous suspension poses the risk of batch-to-batch variations. Therefore, the aim of the study was the establishment of a reproducible and up-scalable method for the preparation of well-defined polyplexes.Polyplexes consisting of pCMVLuc plasmid and 22 kDa linear polyethylenimine (LPEI) were prepared by classical pipetting or with a micro-mixer method using different mixing speeds and plasmid DNA concentrations (20-400 μg/mL). The z-average diameter of the polyplexes was measured by dynamic light scattering. Metabolic activity and transfection efficiency was evaluated on murine neuroblastoma cells after transfection with polyplexes.When varying mixing speeds of the micro-mixer, polyplex size (59-197 nm) and polydispersity index (0.05-0.19) could be directly controlled. The z-average diameter (65-170 nm) and polydispersity index (0.05-0.22) of the polyplexes increased with increasing plasmid DNA concentration (20-400 μg/mL).The established up-scaled micro-mixer method allows the standardized and reproducible preparation of well-defined, transfection-competent plasmid/LPEI polyplexes with high reproducibility.     

Cellular delivery of PEGylated PLGA nanoparticles

Objectives The objective of this study was to investigate the efficiency of uptake of PEGylated polylactide‐co‐gycolide (PLGA) nanoparticles by breast cancer cells. Methods Nanoparticles of PLGA containing various amounts of polyethylene glycol (PEG, 5%–15%) were prepared using a double emulsion solvent evaporation method. The nanoparticles were loaded with coumarin‐6 (C6) as a fluorescence marker. The particles were characterized for surface morphology, particle size, zeta potential, and for cellular uptake by 4T1 murine breast cancer cells. Key findings Irrespective of the amount of PEG, all formulations yielded smooth spherical particles. However, a comparison of the particle size of various formulations showed bimodal distribution of particles. Each formulation was later passed through a 1.2 µm filter to obtain target size particles (114–335 nm) with zeta potentials ranging from ?2.8 mV to ?26.2 mV. While PLGA‐PEG di‐block (15% PEG) formulation showed significantly higher 4T1 cellular uptake than all other formulations, there was no statistical difference in cellular uptake among PLGA, PLGA‐PEG‐PLGA tri‐block (10% PEG), PLGA‐PEG di‐block (5% PEG) and PLGA‐PEG di‐block (10% PEG) nanoparticles. Conclusion These preliminary findings indicated that the nanoparticle formulation prepared with 15% PEGylated PLGA showed maximum cellular uptake due to it having the smallest particle size and lowest zeta potential.     

Phagocytic uptake by mouse peritoneal macrophages of microspheres coated with phosphocholine or polyethylene glycol phosphate-derived perfluoroalkylated surfactants

A series of perfluoroalkylated amphiphiles derived from phosphocholine (PC) and polyethylene glycol (PEG) phosphates has been studied and compared to hydrocarbon analogs with respect to their ability to modify the in vitro protein adsorption, and phagocytic uptake by mouse peritoneal macrophages of polystyrene microspheres coated with these surfactants. A significant correlation between protein adsorption and phagocytosis was seen. Within the PC-derived amphiphiles investigated, those with the shorter C2 and C5 spacers between the fluorinated tail and the phosphocholine group, F8C2PC and F8C5PC, caused significantly lower protein adsorption and a decrease of phagocytic uptake of the microspheres in serum vs a buffer. Phagocytic uptake is then comparable to that observed when pegylated surfactants are used as the coating material. These effects were no longer seen when the spacer was longer, as in F8C11PC, with the non-fluorinated analogues C10PC and C15PC, or when one methyl group was replaced by an ethyl group in the phosphocholine polar head. The beneficial impact of the fluorinated tail thus appear to be related to its distance from the surfactant film's external surface and/or to the lipophobic character of the surfactant. Without serum present phagocytic uptake was lower for the fluorinated surfactants with hydrophilic PEG phosphate head-groups, F8C5PPEG 2000 and F8C5P[PEG 750]2, than for the PC derivatives, although it was significantly greater than with Pluronic F-68 or DSPE-PEG5000. Phagocytosis was, however, not reduced in the presence of serum and the difference between these surfactants and the fluorinated PC derivatives was no longer appreciable.     

Specific gene transfer mediated by galactosylated poly-L-lysine into hepatoma cells

Plasmid DNA/galactosylated poly-L-lysine(GalPLL) complex was used to transfer luciferase reporter gene in vitro into human hepatoma cells by a receptor-mediated endocytosis process. DNA was combined with galPLL via charge interaction (DNA:GalPLL:fusogenic peptide, 1:0.4:5, w/w/w) and the resulting complex was characterized by dynamic light scattering, gel retardation assay and zeta potential analyzer to determine the particle size, electrostatic charge interaction, and apparent surface charge. The complex was tested for the efficiency of gene transfer in cultured human hepatoblastoma cell line Hep G2 and fibroblast cells NIH/3T3 in vitro. The mean diameter of the complex (DNA:GalPLL=1:0.4, w/w) was 256+/-34.8 nm, and at this ratio, it was positively charged (zeta potential of this complex was 10.1 mV). Hep G2 cells, which express a galactose specific membrane lectin, were efficiently and selectively transfected with the RSV Luc/GalPLL complex in a sugar-dependent manner. NIH/3T3 cells, which do not express the galactose-specific membrane lectin, showed only a marginal level of gene expression. The transfection efficiency of GalPLL-conjugated DNA complex into Hep G2 cells was greatly enhanced in the presence of fusogenic peptide that can disrupt endosomes, where the GalPLL-DNA complex is entrapped with the fusogenic peptide. With the fusogenic peptide KALA, the luciferase activity in Hep G2 cells was ten-fold higher than that of cells transfected in the absence of the fusogenic peptide. Our gene transfer formulation may find potential application for the gene therapy of liver diseases.     

Cytotoxicity of monodispersed chitosan nanoparticles against the Caco-2 cells

Published toxicology data on chitosan nanoparticles (NP) often lack direct correlation to the in situ size and surface characteristics of the nanoparticles, and the repeated NP assaults as experienced in chronic use. The aim of this paper was to breach these gaps. Chitosan nanoparticles synthesized by spinning disc processing were characterised for size and zeta potential in HBSS and EMEM at pHs 6.0 and 7.4. Cytotoxicity against the Caco-2 cells was evaluated by measuring the changes in intracellular mitochondrial dehydrogenase activity, TEER and sodium fluorescein transport data and cell morphology. Cellular uptake of NP was observed under the confocal microscope. Contrary to established norms, the collective data suggest that the in vitro cytotoxicity of NP against the Caco-2 cells was less influenced by positive surface charges than by the particle size. Particle size was in turn determined by the pH of the medium in which the NP was dispersed, with the mean size ranging from 25 to 333 nm. At exposure concentration of 0.1%, NP of 25 ± 7 nm (zeta potential 5.3 ± 2.8 mV) was internalised by the Caco-2 cells, and the particles were observed to inflict extensive damage to the intracellular organelles. Concurrently, the transport of materials along the paracellular pathway was significantly facilitated. The Caco-2 cells were, however, capable of recovering from such assaults 5 days following NP removal, although a repeat NP exposure was observed to produce similar effects to the 1st exposure, with the cells exhibiting comparable resiliency to the 2nd assault.