Release of dexamethasone from PLGA nanoparticles entrapped into dextran/poly(vinyl alcohol) hydrogels

Hydrogels based on blends of poly(vinyl alcohol) (PVA) with dextran were prepared by a physical cross-linking procedure and used as matrices for the entrapment of biodegradable nanoparticles loaded with dexamethasone. The nanoparticles were prepared, by a solvent evaporation technique, using biodegradable copolymers of poly(lactic acid)–poly(glycolic acid) (PLGA). Size, morphology and surface characteristics of the nanoparticles were evaluated by scanning electron microscopy. The mechanism of drug release from the nanoparticles entrapped into the PVA-based matrices was studied and compared to that from free nanoparticles. The effect of dextran on the in vitro release profile of dexamethasone from the hydrogels was investigated. The obtained results indicate that PLGA nanoparticles are able to release dexamethasone following a diffusion-controlled mechanism. The entrapment of the nanoparticles into the hydrogels affects only slightly this mechanism of drug release. In addition, dextran/PVA hydrogels release a higher amount of drug with respect to pure PVA hydrogels and by increasing dextran content in the hydrogels, the amount of drug released increases.     

Mg–Al layered double hydroxide–methotrexate nanohybrid drug delivery system: Evaluation of efficacy

Mg–Al layered double hydroxide nanoparticles were synthesized by one-pot co-precipitation method and anticancerous drug methotrexate was incorporated into it by in-situ ion exchange. The LDH–MTX nanohybrid produced moderately stable suspension in water, as predicted by zeta potential measurement. X-ray diffraction revealed that the basal spacing increased to nearly twice the same for pristine LDH on MTX intercalation. Thermogravimetric analyses confirmed an increase in thermal stability of the intercalated drug in the LDH framework. A striking enhancement in efficacy/sensitivity of MTX on the HCT-116 cells was obtained when intercalated within the LDH layers, as revealed by the attainment of half maximal inhibitory concentration of LDH–MTX nanohybrid by 48 h, whereas, bare MTX required 72 h for the same. The MTX release from MgAl-LDH–MTX hybrids in phosphate buffer saline at pH 7.4 followed a relatively slow, first order kinetics and was complete within 8 days following diffusion and crystal dissolution mechanism.     

Methotrexate-conjugated L-lysine coated iron oxide magnetic nanoparticles for inhibition of MCF-7 breast cancer cells

Methotrexate (MTX), a stoichiometric inhibitor of dihydrofolate reductase enzyme, is a chemotherapeutic agent for treating a diversity of neoplasms. In this study, we design and developed a new formulation of MTX that serves as drug carrier and examined its cytotoxic effect in vitro. This target drug delivery system is dependent on the release of the MTX within the lysosomal compartment. The iron oxide magnetic nanoparticles (IONPs) were first surface-coated with L-lysine and subsequently conjugated with MTX through amidation between the carboxylic acid end groups on MTX and the amine groups on the IONPs surface. MTX-conjugated L-lysine coated IONPs (F-Lys-MTX NPs) was characterized by X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, vibrating sample magnetometer, and transmission electron microscopy techniques. The cytotoxicity of the void of MTX and F-Lys-MTX NPs were compared to each other by MTT assay of the treated MCF-7 cell lines. The results showed that the ζ-potential of F-Lys-MTX NPs was about ?5.49?mV and the average size was 43.72?±?4.73?nm. Model studies exhibited the release of MTX via peptide bond cleavage in the presence of proteinase K and at low pH. These studies specify that F-Lys-MTX NPs have a very remarkable anticancer effect, for breast cancer cell lines.     

Effect of MgO nanofillers on burst release reduction from hydrogel nanocomposites

In this study, MgO nanoparticles are applied to control the initial burst release by modification of matrix structure, thereby affecting the release mechanism. The effects of MgO nanofiller loading on the in vitro release of a model drug are investigated. Surface topography and release kinetics of hydrogel nanocomposites are also studied in order to have better insight into the release mechanism. It was found that the incorporation of MgO nanofillers can significantly decrease the initial burst release. The effect of genipin (GN) on burst release was also compared with MgO nanoparticles, and it was found that the impact of MgO on burst release reduction is more obvious than GN; however, GN cross-linking caused greater final release compared to blanks and nanocomposites. To confirm the capability of nanocomposite hydrogels to reduce burst release, the release of β-carotene in Simulated Gastric Fluid and Simulated Intestinal Fluid was also carried out. Thus, the application of MgO nanoparticles seems to be a promising strategy to control burst release.     

Poly(vinyl alcohol) hydrogels as hydrophilic matrices for the release of lipophilic drugs loaded in PLGA nanoparticles

Poly(vinyl alcohol) (PVA) hydrogels prepared by a freeze-thawing procedure were evaluated as matrices for the release of water-insoluble drugs such as dexamethasone. As it is impossible to directly entrap a lipophilic drug into a hydrophilic matrix, a novel mechanism has been designed based on producing biodegradable nanoparticles loaded with the drug, that could then be entrapped into the hydrogels. Nanoparticles were prepared by a solvent evaporation technique using a biodegradable copolymer of poly(lactic acid)-poly(glycolic acid) (PLGA). The effects of several processing parameters on particle properties were investigated. The drug release from free nanoparticles was compared to that from the nanoparticles entrapped into the PVA matrices. It was observed that the release profile of the drug is not significantly affected by the PVA matrix. A correlation was found between the amount of drug released and the PVA concentration in the hydrogels: the percentage of drug released, as a function of time, decreased by increasing PVA concentration, indicating that PVA concentration can be used as a tool in modulating the release of the drug.     

Methotrexate loaded solid lipid nanoparticles (SLN) for effective treatment of carcinoma

Solid Lipid Nanoparticles (SLN) containing Methotrexate (MTX), an anticancer drug for intravenous administration was formulated and characterized. The SLN dispersions with MTX, stearic acid, and soya lecithin in the ratio of 1:4:1, 1:4:1.5, and 1:4:2, sodium taurodeoxycholate and distilled water were prepared by micro emulsification solidification method. The results show that the prepared MTX-SLN particles (with MTX-Stearic acid-Soya lecithin--1:4:2) have an average size of 270 nm with 51.3% drug entrapment. The in-vitro release was attained up to 15th h. The pharmacokinetic study reveals that the half-life and MRT of SLNs were higher than MTX solution. The life span of EAC (Ehrlich Ascite Carcinoma) bearing mice was increased when treated with MTX-SLNs (Methotrexate nanoparticles). These results clearly indicate that SLNs are a promising sustained release drug targeting system for lipophilic antitumour drugs.     

In Vitro Evaluation of Polyisobutylcyanoacrylate Nanoparticles as a Controlled Drug Carrier for Theophylline

Abstract

Theophylline nanoparticles were prepared by emulsifier-free emulsion polymerization technique in continuos aqueous phase. The polymerization process was carried out at a pH 3. Different concentrations of isobutylcyacoacrylate (IBCA) were used to investigate the effect of monomer concentration. The in vitro release of theophylline in phosphate buffer was studied. An HPLC assay was used to follow the release of the drug from the nanospheres. This polymerization technique was able to hold 2349% of the drug initially dissolved in the aqueous medium. The percentage drug loading is a monomer concentration dependent. Increasing the monomer concentration above 40 μL per mL resulted in a less significant increase in the percentage drug loading. The percentage of drug retained in nanospheres up to 24 hr followed first order kinetics (r = 0.94-0.98). The release rate constant of theophylline from nanoparticles is inversely related to the monomer concentration in the initial solution (r = 0.996). In the mean time the release rate constant of theophylline from the nanoparticles was directly related to the amount of the drug added initially (r = 0.990).     

In Vitro Evaluation of Polyisobutylcyanoacrylate Nanoparticles as a Controlled Drug Carrier for Theophylline

Theophylline nanoparticles were prepared by emulsifier-free emulsion polymerization technique in continuos aqueous phase. The polymerization process was carried out at a pH 3. Different concentrations of isobutylcyacoacrylate (IBCA) were used to investigate the effect of monomer concentration. The in vitro release of theophylline in phosphate buffer was studied. An HPLC assay was used to follow the release of the drug from the nanospheres. This polymerization technique was able to hold 2349% of the drug initially dissolved in the aqueous medium. The percentage drug loading is a monomer concentration dependent. Increasing the monomer concentration above 40 μL per mL resulted in a less significant increase in the percentage drug loading. The percentage of drug retained in nanospheres up to 24 hr followed first order kinetics (r = 0.94-0.98). The release rate constant of theophylline from nanoparticles is inversely related to the monomer concentration in the initial solution (r = 0.996). In the mean time the release rate constant of theophylline from the nanoparticles was directly related to the amount of the drug added initially (r = 0.990).     

Methotrexate-grafted-oligochitosan micelles as drug carriers: synthesis and biological evaluations

The novel amphiphilic derivatives of Methotrexate–chitosan oligosaccharide (MTX–CHO) with different molar feeding ratios of MTX were synthesized. The degree of MTX substitution ranged from 4.47 to 13.5 %. MTX–CHO copolymer formed micelles with an average size of 134.6 ± 14.52 to 236.6 ± 30.01 nm, and zeta potential of 20 ± 5 to 16.8 ± 7.74 mV. The critical micelle concentration was found to range from 125 to 0.56 mg/l. Analysis of micelles with different degree of substitutions (DSs) revealed that the size of micelles decreased by increasing DS while zeta potential was reduced. Release study indicated that drug content had effect on the release rate. With increasing amount of loaded drug in the micelle, release rate was decreased. Drug loaded and unloaded MTX–CHO micelles showed significant cytotoxicity on MDA-MB-231. Loaded micelle was more effective than unloaded one which indicated that conjugation could reduce efficacy of MTX. The viability of MDA-MB-231 in presence of drug loaded micelles was significantly decreased and cell viability at 1 µg/ml was 45.17 ± 9 % while the viability of unloaded micelles was 91.86 ± 9.88. These phenomena make MTX–CHO micelles as a good candidate for hydrophobic anticancer drug carrier.     

Synthesis and characterization of photocatalytic polyurethane and poly(methyl methacrylate) microcapsules for the controlled release of methotrexate

Abstract

The aim of this work is to prepare ultraviolet (UV) triggered controlled release of compounds from microcapsule systems (MCs). Polyurethane (PU) and poly(methyl methacrylate) (PMMA) microcapsules were studied with/without chemical functionalization using photocatalytic TiO₂ nanoparticles (NPs) on their surface. Once TiO₂ nanoparticles are illuminated with UV light (λ?=?370?nm), they initiate the rupture of the polymeric bonds of the microcapsule and subsequently initiate the encapsulated compound release, methotrexate (MTX) or rhodamine (Rh), in the present work. The size, polydispersity, charge, and yield of all MCs were measured, being the methotrexate drug release for all systems determined and compared with and without functionalization with TiO₂ NPs, under dark, visible light and UV illumination in vitro. Finally, the Rh release was characterized using fluorescence microscopy. The TiO₂ NPs size is around 10?nm, as determined by X-ray diffraction experiments. The PU MCs average size is around 60?µm, its electric charge +3.11?mV and yield around 85%. As for the PMMA MCs, the average size is around 280?µm, its electric charge ?7.2?mV and yield around 25% and 30% for both MTX and Rh, respectively. In general, adding TiO₂ NPs or the encapsulated products to the MCs does not affect the size but functionalization with TiO₂ NPs lowers the electric charge. Microcapsules functionalized with TiO₂ nanoparticles and irradiated with UV light presented the highest release of MTX and Rh. All other samples showed lower drug release levels when studied under the same conditions.     

pH- and thermo-sensitive MTX-loaded magnetic nanocomposites: synthesis,characterization, and in vitro studies on A549 lung cancer cell and MR imaging

In the current study, we proposed a facile method for fabrication of multifunctional pH- and thermo-sensitive magnetic nanocomposites (MNCs) as a theranostic agent for using in targeted drug delivery and magnetic resonance imaging (MRI). To this end, we decorated Fe₃O₄ magnetic nanoparticles (MNPs) with N,N-dimethylaminoethyl methacrylate (DMAEMA) and N-isopropylacrylamide (NIPAAm), best known for their pH- and thermo-sensitive properties, respectively. We also conjugated mesoporous silica nanoparticles (MSNs) to polymer matrix acting as drug container to enhance the drug encapsulation efficacy. Methotroxate (MTX) as a model drug was successfully loaded in MNCs (M-MNCs) via surface adsorption onto MSNs and electrostatic interaction between drug and carrier. The pH- and temperature-triggered release of MTX was concluded through the evaluation of in vitro release at both physiological and simulated tumor tissue conditions. Based on in vitro cytotoxicity assay results, M-MNCs significantly revealed higher antitumor activity compared to free MTX. In vitro MR susceptibility experiment showed that M-MNCs relatively possessed high transverse relaxivity (r₂) of about 0.15?mM^?1·ms^?1 and a linear relationship between the transverse relaxation rate (R₂) and the Fe concentration in the M-MNCs was also demonstrated. Therefore, the designed MNCs can potentially become smart drug carrier, while they also can be promising MRI negative contrast agent.     

Chitosan Nanoparticles for Prolonged Delivery of Timolol Maleate

Timolol maleate-loaded chitosan (CS) nanoparticles were prepared by desolvation method. Experimental variables such as molecular weight of CS and amount of crosslinking agent were varied to study their effect on drug entrapment efficiency, size and release rates of nanoparticles. Chemical stability of timolol maleate (TM) and crosslinking of CS were confirmed by Fourier transform infrared spectroscopy. Differential scanning calorimetric studies were performed on drug-loaded nanoparticles to investigate crystalline nature of the drug after entrapment. Results indicated amorphous dispersion of drug in the polymer matrix. Scanning electron microscopy revealed irregularly shaped particles. Mean particle size of nanoparticles ranged between 118 and 203 nm, while zeta potential ranged between +17 and +22 mV. Entrapment efficiency of nanoparticles ranged between 47.6 and 63.0%. In-vitro release studies were performed in phosphate buffer saline of pH 7.4. A slow release of TM up to 24 h was observed. A 3² full factorial design was employed and second-order regression models were used to study the response (% drug release at 4 h). Release data as analyzed by an empirical relationship suggested that drug release deviated from the Fickian trend.     

Intracellular drug delivery of layered double hydroxide nanoparticles

Intracellular drug delivery of layered double hydroxide (LDH) nanocarriers have been examined in human osteosarcoma Saos-2 cell culture line by both electron and confocal microscopies. For transmission electron microsopic (TEM) study, LDHs and anticancer drug, methotrexate (MTX) loaded LDHs were synthesized and the particle size was controlled. From the scanning electron microscopic (SEM) studies, morphologies of LDH nanoparticle and its MTX intercalated form were proven to be platelike hexagonal with an average size of approximately 150 nm. In order to understand the cellular penetration behavior, both nanoparticles were treated to human osteosarcoma Saos-2 cell culture lines and the cellular uptake pattern with respect to incubation time was observed by TEM and SEM. We observed that the nanoparticles are attached at the cellular membrane at first and then internalized into the cells via endocytosis within 1 h. Then are located in the intracellular vacuole (endosome). In order to examine the intracellular drug delivery mechanism of LDH nanoparticles, fluorescein 5-isothiocyanate (FITC) labeled MTX was intercalated into LDH and treated on Saos-2 cells. Laser scanning confocal microscopic studies revealed that the FITC-MTX molecules were first internalized with LDH nanocarriers via endocytosis, and located in endosome to deliver loaded drug to target cellular organ. It was, therefore, concluded that LDH could play a role as drug delivery nanocarriers.     

Preparation and optimization of doxorubicin-loaded albumin nanoparticles using response surface methodology

Background: The objective of this work was to optimize the preparation of doxorubicin-loaded albumin nanoparticles (Dox-A-Nps) through desolvation procedures using response surface methodology (RSM). A central composite design (CCD) for four factors at five levels was used in this study.

Method: Albumin nanoparticles were prepared through a desolvation method and were optimized in the aid of CCD. Albumin concentration, amount of doxorubicin, pH values, and percentage of glutaraldehyde were selected as independent variables, particle size, zeta potential, drug loading, encapsulation efficiency, and nanoparticles yield were chosen as response variables. RSM and multiple response optimizations utilizing a quadratic polynomial equation were used to obtain an optimal formulation.

Results: The optimal formulation for Dox-A-Nps was composed of albumin concentration of 17?mg/ml, amount of doxorubicin of 2?mg/ml, pH value is 9 and percentage of glutaraldehyde of 125% of the theoretic amount, under which the optimized conditions gave rise to the actual average value of mean particle size (151?±?0.43?nm), zeta potential (?18.8?±?0.21 mV), drug loading efficiency (21.4?±?0.70%), drug entrapment efficiency (76.9?±?0.21%) and nanoparticles yield (82.0?±?0.34%). The storage stability experiments proved that Dox-A-Nps stable in 4°C over the period of 4 months. The in vitro experiments showed a burst release at the initial stage and followed by a prolonged release of Dox from albumin nanoparticles up to 60?h.

Conclusions: This study showed that the RSM-CCD method could efficiently be applied for the modeling of nanoparticles, which laid the foundation of the further research of immuno nanoparticles.     

Anticancer drug-inorganic nanohybrid and its cellular interaction

An anticancer drug, methotrexate (MTX), has been successfully hybridized with layered double hydroxide (LDH) through co-precipitation route to produce MTX-LDH nanohybrids (MTX-LDH). According to the X-ray diffraction and FT-IR spectroscopy, it was confirmed that MTX molecules are stabilized in the interlayer space of LDHs by electrostatic interaction, maintaining their functional groups and structural integrity. According to the drug release study, the total amount of released MTX from the LDH lattice was determined to be larger under a simulated intracellular lysosomal condition (pH = 4.5) than simulated body fluid one (pH = 7.4). It is, therefore, expected that the MTX molecules in MTX-LDH can be effectively released in lysosomes, since the MTX release could be accelerated via ion-exchange reaction and dissolution of LDH in an acidic lysosomal condition. We also examined the anticancer efficacy of MTX-LDH in human breast adenocarcinoma MCF-7 cells. The cellular uptake of MTX was considerably higher in MTX-LDH-treated cells than in free MTX-treated cells, giving a lower IC50 value for the former than the latter. All the results demonstrated that the MTX-LDH nanohybrid allows the efficient drug delivery in cells, and thus enhances drug efficacy.     

Biodegradable nanoparticles for improved kidney bioavailability of rhein: preparation,characterization, plasma,and kidney pharmacokinetics

The aim of this work is to develop biodegradable nanoparticles for improved kidney bioavailability of rhein (RH). RH-loaded nanoparticles were prepared using an emulsification solvent evaporation method and fully characterized by several techniques. Kidney pharmacokinetics was assessed by implanting a microdialysis probe in rat's kidney cortex. Blood samples were simultaneously collected (via femoral artery) for assessing plasma pharmacokinetics. Optimized nanoparticles were small, with a mean particle size of 132.6?±?5.95?nm, and homogeneously dispersed. The charge on the particles was nearly zero, the encapsulation efficiency was 62.71?±?3.02%, and the drug loading was 1.56?±?0.15%. In vitro release of RH from the nanoparticles showed an initial burst release followed by a sustained release. Plasma and kidney pharmacokinetics showed that encapsulation of RH into nanoparticles significantly increased its kidney bioavailability (AUC_kidney/AUC_plasma?=?0.586?±?0.072), clearly indicating that nanoparticles are a promising strategy for kidney drug delivery.     

Combination of β-cyclodextrin inclusion complex and self-microemulsifying drug delivery system for photostability and enhanced oral bioavailability of methotrexate: novel technique

In the present study, we prepared an inclusion complex of methotrexate (MTX) with β-cyclodextrin (β-CD) in order to decrease its photosensitivity and enhance its aqueous solubility. Then we incorporated this inclusion complex in a self-microemulsifying drug delivery system (SMEDDS) overall to increase its oral bioavailability. The inclusion complex has been prepared by freeze drying method and characterized by differential scanning calorimetry (DSC), ultraviolet (UV), and infrared (IR) spectroscopy assays. The proper molecular ratio of MTX/β-CD was found to be of 1:7, and the water-solubility of MTX was increased in an average of 10-fold. The photostability studies showed that the MTX became stable on exposure to light. Construction of pseudoternary diagrams were investigated to prepare a MTX/β-CD inclusion complex loaded SMEDDS which was characterized by measuring the particle size and the zeta-potential. The optimum formulation of SMEDDS was a system consisting of ethyl oleate, tween 80, and propylene glycol with a mean droplet size of 39.42?nm. In vitro drug release in different pH media showed that the release profile of MTX from the MTX/β-CD loaded SMEDDS was influenced by the pH of the release medium and presented the characteristics of a sustained release profile. Finally, in-vivo studies showed an enhancement of the bioavailability of MTX from the MTX/β-CD loaded SMEDDS form of 1.57-fold. We concluded that the β-CD inclusion complex loaded SMEDDS improved the chemical and physiological properties of MTX and could be a promising means for the delivery of MTX and other unstable and lipophilic drugs by oral route.     

Development of Drug Delivery Systems from Vegetal Proteins: Legumin Nanoparticles

Legumin (storage protein from Pisum sativum L.) nanoparticles of about 250 nm were prepared by means of a pH-coacervation method and chemical cross-linking with glutaraldehyde. This preparative method enabled to avoid the use of organic solvents but only yielded about 27% of protein added as nanoparticles. No significant differences in size, percentage yield, and surface charge were obtained between legumin nanoparticles cross-linked with different glutaraldehyde concentrations. Legumin nanoparticles were quite stable in phosphate-buffered saline (PBS). They follow a zero-order degradation, and by increasing glutaraldehyde concentration, a longer half-life (t₅₀) was obtained. The amount of methylene blue (MB), used as a model of hydrophilic drug, loaded was about 6.2% of the initial dye. Its release from the nanoparticles consisted of a rapid initial phase followed by a slower second period. The rates in this second phase were inversely related to the degree of cross-linking.     

Preparation and characterization of self-assemblied nanoparticles based on folic acid modified carboxymethyl chitosan

Folate (FA) modified carboxymethyl chitosan (FCC) has been synthesized and the hydrogel nanoparticles can be prepared after the sonication. Formation and characteristics of nanoparticles of FCC were studied by fluorescence spectroscopy and dynamic light scattering methods. The critical aggregation concentration value of FCC in water was 9.34 × 10⁻² mg/ml and the mean hydrodynamic diameter of particle was 267.8 nm. The morphology of nanoparticles was observed by transmission electron microscopy which had spherical shape. Loading capacity (LC), loading efficiency (LE) and the in vitro release profiles of nanoparticles were investigated by doxorubicin (DOX) as a model drug. When the initially added amount of DOX versus the constant amount of FCC polymer was increased, the LC in the nanoparticles was gradually increased and the LE decreased. The in vitro release profile of the DOX from the FCC nanoparticles exhibited sustained release. Cellular uptake of FCC nanoparticles was found to be higher than that of nanoparticles based on linoleic acid (LA) modified carboxymethyl chitosan because of the FA-receptor-mediated endocytosis, thereby providing higher cytotoxicity against Hela cells.     

Development of biocompatible fluorescent gelatin nanocarriers for cell imaging and anticancer drug targeting

In recent years, fluorescent carbon dots (CDs) have attracted a great deal of attention in imaging and related biomedical applications due to their excellent photoluminescence properties, low cost, high quantum yield and low cytotoxicity in comparison with semiconductor quantum dots based on metallic elements. In this paper, a new and simple design for development of CDs/gelatin nanoparticles (CDs/GNPs) is described which used as a novel methotrexate (MTX) nanocarrier and MCF-7 cell imaging. The obtained fluorescent nanocarriers were characterized using FTIR, SEM, XRD, DLS, PL, TGA, and zeta-potential analysis. Afterward, the performance of developed NPs was investigated through different in vitro tests such as MTT assay, fluorescence microscopy, and flow cytometry analyses. MTX was successfully loaded into the fluorescent NPs at physiological pH (7.4) by ionic interactions between anionic carboxylate groups of MTX and cationic amino groups on the surface of NPs. MTX releasing ability of the obtained nanocarrier was illustrated through the comparison of in vitro drug release at both simulated tumor tissue and physiological environment. The MTT assay revealed that the MTX-loaded nanocarriers have higher cytotoxicity in MCF-7 breast cancer cells than nanocarriers without MTX. Upon the obtained results, our fluorescent nanocarriers hold great potential as drug delivery carriers for the targeted MTX delivery to the cancer cells and biological fluorescent labeling.