Fabrication of 3D chitosan/polyvinyl alcohol/brushite nanofibrous scaffold for bone tissue engineering by electrospinning using a novel falling film collector.

Despite its advantages, electrospinning has limited effectiveness in 3D scaffolding due to the high density of fibers it produces. In this research, a novel electrospinning collector was developed to overcome this constraint. An aqueous suspension containing chitosan/polyvinyl alcohol nanofibers was prepared employing a unique falling film collector. Suspension molding by freeze-drying resulted in a 3D nanofibrous scaffold (3D-NF). The mineralized scaffold was obtained by brushite deposition on 3D-NF using wet chemical mineralization by new sodium tripolyphosphate and calcium chloride dihydrate precursors. The 3D-NF was optimized and compared with the conventional electrospun 2D nanofibrous scaffold (2D-NF) and the 3D freeze-dried scaffold (3D-FD). Both minor fibrous and major freeze-dried pore shapes were present in 3D-NFs with sizes of 16.11-24.32 µm and 97.64-234.41 µm, respectively. The scaffolds' porosity increased by 53 % to 73 % compared to 2D-NFs. Besides thermal stability, mineralization improved the 3D-NF's ultimate strength and elastic modulus by 2.2 and 4.7 times, respectively. In vitro cell studies using rat bone marrow mesenchymal cells confirmed cell infiltration up to 290 µm and scaffold biocompatibility. The 3D-NFs given nanofibers and brushite inclusion exhibited considerable osteoinductivity. Therefore, falling film collectors can potentially be applied to prepare 3D-NFs from electrospinning without post-processing.

Injectable chitosan hydrogel embedding modified halloysite nanotubes for bone tissue engineering.

Low mechanical strength and untargeted osteoinduction of chitosan hydrogel limit its application for bone regeneration. This study aimed to develop an injectable chitosan hydrogel with enhanced mechanical strength and improved osteoinductivity for bone tissue engineering. For this purpose, chitosan-modified halloysite nanotubes (mHNTs) were synthesized first. Then, icariin as a bone inducer was loaded into mHNTs (IC@mHNTs), resulting in a sustained drug release system. Further, nanocomposite chitosan/mHNTs hydrogels were prepared by the sol-gel transition, leading to decreased gelation time and temperature and enhanced mechanical strength of the resulting scaffolds. The mesenchymal stem cells were encapsulated into the hydrogels, and in vitro viability assays showed scaffold biocompatibility. Moreover, embedded mHNTs or IC@mHNTs in the scaffold resulted in enhanced proliferation and bone differentiation of encapsulated cells. It was collectively demonstrated that the injectable in situ forming nanocomposite chitosan hydrogel loaded with IC@mHNTs is a promising candidate for bone regeneration.

Thermoresponsive Nanogels Based on Different Polymeric Moieties for Biomedical Applications.

Nanogels, or nanostructured hydrogels, are one of the most interesting materials in biomedical engineering. Nanogels are widely used in medical applications, such as in cancer therapy, targeted delivery of proteins, genes and DNAs, and scaffolds in tissue regeneration. One salient feature of nanogels is their tunable responsiveness to external stimuli. In this review, thermosensitive nanogels are discussed, with a focus on moieties in their chemical structure which are responsible for thermosensitivity. These thermosensitive moieties can be classified into four groups, namely, polymers bearing amide groups, ether groups, vinyl ether groups and hydrophilic polymers bearing hydrophobic groups. These novel thermoresponsive nanogels provide effective drug delivery systems and tissue regeneration constructs for treating patients in many clinical applications, such as targeted, sustained and controlled release.

Quantum dots-ßcyclodextrin-histidine labeled human adipose stem cells-laden chitosan hydrogel for bone tissue engineering.

Mesenchymal stem cells with differentiation ability to diverse cells play a crucial role in tissue engineering. Tracking the fate of these cells during the regeneration of tissue helps to obtain more information about their function. In this study, histidine conjugated ß-cyclodextrin as a cell-penetrating carrier with drug loading ability was attached to QDs nanoparticle (QD-ßCD-His) for stem cell labeling. Traceability of QD-ßCD-His labeled human adipose stem cells (hASCs) was monitored in 2D cell culture and 3D temperature-sensitive chitosan hydrogel scaffold. Dexamethasone (Dex) as an osteoinductive drug was loaded into QD-ßCD-His nano-carrier (QD-ßCD-His@Dex) to induce bone differentiation of labeled cells. Overall results indicated that QD-ßCD-His@Dex is a promising dual-purpose nano-carrier for stem cell labeling with osteoinductive potential in cell therapy as well as tissue engineering scaffolds.

Osteogenic induction of human mesenchymal stem cells in multilayered electrospun scaffolds at different flow rates and configurations in a perfusion bioreactor.

Electrospun scaffolds are potentially interesting in bone tissue engineering due to a strong structural similarity to the natural bone matrix. To investigate the osteogenic behavior of cells on the scaffolds, dynamic culture of cells is essential to simulate the biological environment. In the present study, human mesenchymal stem cells (hMSCs) were cultured on multilayer nanohydroxyapatite-polycaprolactone electrospun scaffolds at different configurations (horizontal with or without pressure and parallel with the medium flow) and flow rates in a perfusion bioreactor. Alkaline phosphatase (ALP) activity, cell viability, Ca deposition and RUNX2 expression were determined in three different dynamic states, and compared with static culture after 1, 3, 7, and 14 days. Among dynamic groups, RUNX2 gene expression upregulated more in a horizontal state at a low flow rate without mechanical pressure (LF) and parallel flow (PF), than static group on day 7. At a high flow rate with mechanical pressure, Ca deposition and ALP activity increased 2.34 and 1.7 folds more than in static culture over 7 days, respectively. Furthermore, ALP activity, Ca deposition and RUNX2 gene expression increased in PF samples. PF provided longer culture time with higher cell differentiation. Therefore, high flow rate with mechanical pressure and PF are suggested for producing differentiated cell structure for bone tissue engineering.

Reduction of marginal mass required for successful islet transplantation in a diabetic rat model using adipose tissue-derived mesenchymal stromal cells.

BACKGROUND AIMS: Adipose tissue-derived mesenchymal stromal cells (AT-MSCs), widely known as multipotent progenitors, release several cytokines that support cell survival and repair. There are in vitro and in vivo studies reporting the regenerative role of AT-MSCs possibly mediated by their protective effects on functional islet cells as well as their capacity to differentiate into insulin-producing cells (IPCs). METHODS: On such a basis, our goal in the present study was to use three different models including direct and indirect co-cultures and islet-derived conditioned medium (CM) to differentiate AT-MSCs into IPCs and to illuminate the molecular mechanisms of the beneficial impact of AT-MSCs on pancreatic islet functionality. Furthermore, we combined in vitro co-culture of islets and AT-MSCs with in vivo assessment of islet graft function to assess whether co-transplantation of islets with AT-MSCs can reduce marginal mass required for successful islet transplantation and prolong graft function in a diabetic rat model. RESULTS: Our findings demonstrated that AT-MSCs are suitable for creating a microenvironment favorable for the repair and longevity of the pancreas ß cells through the improvement of islet survival and maintenance of cell morphology and insulin secretion due to their potent properties in differentiation. Most importantly, hybrid transplantation of islets with AT-MSCs significantly promoted survival, engraftment and insulin-producing function of the graft and reduced the islet mass required for reversal of diabetes. CONCLUSIONS: This strategy might be of therapeutic potential solving the problem of donor islet material loss that currently limits the application of allogeneic islet transplantation as a more widespread therapy for type 1 diabetes.

Self-assembled and pH-sensitive mixed micelles as an intracellular doxorubicin delivery system.

Nanocarrier-based drug delivery systems have been explored extensively in cancer therapy. Among the vast number of different nanocarrier systems applied to deliver chemotherapeutics to cancer tumor, intelligent systems which deliver drug to various sites in the body have attracted considerable attentions. Finding a specific stimulant that triggers the carrier to release its payload in the target tissue is a key parameter for efficacy of delivery systems. Acidic pH of cancer tumor helps a pH-sensitive carrier to release drug at the tumor site. In this study, a pH-sensitive mixed micellar system was developed using Dextran-Stearic Acid (Dex-SA) and Dextran-Histidine (Dex-His) conjugated polymers to deliver doxorubicin (DOX) to cancer cells. Drug release from this micellar system showed higher release rate at acidic pH than that of in neutral environment, where the release was 56 and 76% at pH 7.4 and acidic pH, respectively. Finally, the in vitro cytotoxicity and cell uptake of DOX-loaded micelles and free DOX on U87 MG cell line showed that micellar systems had more anti-proliferation effect and uptake compared to free drug.

Synthesis and application of magnetite dextran-spermine nanoparticles in breast cancer hyperthermia.

Cancer treatment has been very challenging in recent decades. One of the most promising cancer treatment methods is hyperthermia, which increases the tumor temperature (41-45 °C). Magnetic nanoparticles have been widely used for selective targeting of cancer cells. In the present study, magnetic dextran-spermine nanoparticles, conjugated with Anti-HER2 antibody to target breast cancer cells were developed. The magnetic dextran-spermine nanoparticles (DMNPs) were prepared by ionic gelation, followed by conjugation of antibody to them using EDC-NHS method. Then the Prussian blue method was used to estimate the targeting ability and cellular uptake. Cytotoxicity assay by MTT showed that antibody-conjugated MNPs (ADMNPs) have no toxic effect on SKBR3 and human fibroblast cells. Finally, the hyperthermia was applied to show that synthesized ADMNPs, could increase the cancer cells temperature up to 45 °C and kill most of them without affecting normal cells. These observations proved that Anti-HER2 conjugated magnetic dextran-spermine nanoparticles can target and destroy cancer cells and are potentially suitable for cancer treatment.

Transferrin-conjugated magnetic dextran-spermine nanoparticles for targeted drug transport across blood-brain barrier.

Application of many vital hydrophilic medicines have been restricted by blood-brain barrier (BBB) for treatment of brain diseases. In this study, a targeted drug delivery system based on dextran-spermine biopolymer was developed for drug transport across BBB. Drug loaded magnetic dextran-spermine nanoparticles (DS-NPs) were prepared via ionic gelation followed by transferrin (Tf) conjugation as targeting moiety. The characteristics of Tf conjugated nanoparticles (TDS-NPs) were analyzed by different methods and their cytotoxicity effects on U87MG cells were tested. The superparamagnetic characteristic of TDS-NPs was verified by vibration simple magnetometer. Capecitabine loaded TDS-NPs exhibited pH-sensitive release behavior with enhanced cytotoxicity against U87MG cells, compared to DS-NPs and free capecitabine. Prussian-blue staining and TEM-imaging showed the significant cellular uptake of TDS-NPs. Furthermore, a remarkable increase of Fe concentrations in brain was observed following their biodistribution and histological studies in vivo, after 1 and 7 days of post-injection. Enhanced drug transport across BBB and pH-triggered cellular uptake of TDS-NPs indicated that these theranostic nanocarriers are promising candidate for the brain malignance treatment. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2851-2864, 2017.

Osteogenic Differentiation of MSCs on Fibronectin-Coated and nHA-Modified Scaffolds.

The increasing demand for biocompatible bone substitutes has made it a priority to tissue engineering and regenerative medicine scientists. Combination of minerals, growth factors, and extracellular matrix (ECM) proteins with nanofibrous scaffolds is a potential promising strategy for bone reconstruction and clinical applications. In this study, nanohydroxyapatite (nHA) was incorporated in electrospun nanofibrous polycaprolactone (PCL) scaffolds coated with fibronectin (Fn). The potential bone regeneration capacities of these scaffolds were evaluated in vitro and in vivo using mouse mesenchymal stem cells (mMSCs). The interconnected pores and proper mechanical characteristics of the fabricated electrospun PCL mats in combination with nHA and Fn provided suitable environment for cell attachment, proliferation, and enhanced osteogenic differentiation. The synergistic effect of Fn and nHA on the both in vitro and in vivo increase of calcium deposition was assessed by biochemical analysis. In addition, alkaline phosphatase (ALP) activity in nHA-incorporated PCL scaffold (PCL/nHA) and Fn-coated PCL/nHA (PCL/nHA/Fn) were significantly higher in comparison to the control group. Quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) analyses of important bone-related genes (ALP, osteocalcin, osteopontin, and Runx2) revealed that Fn has additive effect on promoting the osteogenic differentiation. The aforementioned results indicated that nanofibrous PCL/nHA scaffold coated with Fn is a promising candidate for bone-tissue engineering applications.

In-Vitro Assessment of Magnetic Dextran-Spermine Nanoparticles for Capecitabine Delivery to Cancerous Cells.

Cationic polymeric nanoparticles have great potential for developing drug delivery systems with limited side effects for tumor medication. The goal of this research is investigation of cationic dextran-spermine polymer (DS) efficacy for improvement of hydrophilic drug delivery to negatively charged cancerous cells. Capecitabine (as a hydrophilic antineoplastic drug) was loaded into the magnetic dextran-spermine nanoparticles (DS-NPs) via ionic gelation. Design of experiments was applied to specify how the significant factors affect size, surface charge and capecitabine entrapment efficiency of the DS-NPs. Physicochemical properties, in-vitro release profile and cellular studies of the optimized DS-NPs were evaluated. The experimental results indicated that DS-NPs with favorable properties can be achieved at an optimized condition of 2 mg/mL DS and 0.75 mg/mL tri-polyphosphate (TPP) concentrations, TPP addition rate of 35 mL/min, pH 3 of DS solution and super paramagnetic iron oxide nanoparticles (SPION)/DS mass ratio of 0.5. The entrapment efficiency of capecitabine was 26.1% at optimum condition and drug release at neutral pH after 24 h and acidic pH within 3 h was 56 and 98%, respectively. The cytotoxicity assessment exhibited that capecitabine loaded DS-NPs was more toxic than corresponding free drug as control. Significant cellular uptake of capecitabine loaded DS-NPs by U87MG glioblastoma cells were proved by Prussian blue staining and TEM, qualitatively. DS-NPs are suitable candidates for delivery of the hydrophilic drugs in cancer treatment and due to positive charge of the dextran-spermine, the uptake of the hydrophilic drugs by the cancerous cells was improved.

Functionalized magnetic dextran-spermine nanocarriers for targeted delivery of doxorubicin to breast cancer cells.

In recent decades, targeted drug delivery systems for breast cancer treatment emerged as an ideal alternative and promising solution to reduce systemic side effects of chemotherapeutic agents. In this study, the preparation and characterization of cationic doxorubicin (DOX) loaded magnetic dextran-spermine (DEX-SP) nanocarriers (DEX-SP-DOX) by ionic gelation were fully investigated. Then, anti-HER2 as a monoclonal antibody (mAb) and targeting ligand was conjugated via EDC/NHS reagents. The binding was confirmed by Bradford assay and further assessments were carried out by size and zeta potential measurements. Cytotoxicity effect and internalization of magnetic nanocarriers were assessed by MTT and Prussian blue assays and transmission electron microscopy (TEM), respectively. DLS measurements indicated that the size of nanocarriers increased from 62 to 84 nm by conjugation of anti-HER2 to them. The in vitro release of DOX from mAb conjugated magnetic nanocarriers at pHs 5 and 7.4 was found to be 85 and 55.5%, respectively. The MTT and Prussian blue assays demonstrated enhanced and selective uptake of DEX-SP-DOX-mAb by SKBR cell (HER2 overexpressed cells) in comparison with unconjugated nanocarriers due to higher cellular binding. The TEM result also confirmed cellular internalization of DEX-SP-DOX-mAb magnetic nanocarriers. These results are very promising for targeted delivery of DOX to HER2 positive breast cancer cells.

Synthesis and characterization of an in situ forming hydrogel using tyramine conjugated high methoxyl gum tragacanth.

In this study, an enzyme catalyzed in situ forming hydrogel based on tyramine conjugated high methoxyl content gum tragacanth (TA-HMGT) was prepared and characterized. TA-HMGT was synthesized via heterogeneous ammonolysis of methyl ester groups of HMGT. Then, the hydrogel was prepared via horseradish peroxidase catalyzed coupling reaction in the presence of hydrogen peroxide. Hydrogel properties, such as gelation time, swelling/degradation behavior and rheological properties could be adjusted by tuning the gelation parameters and extent of tyramine conjugation. This system was a soft elastic hydrogel with appropriate biocompatibility. The fast gelation of the hydrogel is desirable for clinical applications. Also, in vitro bovine serum albumin release from the synthesized hydrogel showed good release profile with limited burst release.

Fibroblasts feeder niche and Flt3 Ligand as a novel inducer of plasmacytoid dendritic cells development in vitro.

Plasmacytoid dendritic cell (pDC), plays central role in antiviral immunity. The aim of this study was to assess the effect of Flt3 ligand (FL) alone or with L929 fibroblast feeder or L929 conditioned media on differentiation of mouse bone marrow (BM) cells into pDC in vitro. Murine BM cells were cultured with FL or with L929 or conditioned media for 9days. The differentiated cells were analyzed using flow cytometry for PDCA-1, B220 and CXCR4. The relative expression of Stat3, CXCR4, CXCR7, IFN-ß, TGF-ß and Runx2 in differentiated cells determined by real time PCR. The development of pDC showed up to 19% increase after co-culture of BM cells with fibroblast feeder. Upregulation of Stat3, Runx2 and CXCR4 due to the presence of fibroblast feeder with FL in culture results in improved pDC development. Furthermore, 30% L929 supernatant along with Flt3 ligand was able to derive pDC up to 8.9% in comparison with FL alone, which was 6.6% in vitro. Thus, for the first time we introduced L929 fibroblast feeder as a niche producer of M-CSF and probably other growth factors and chemokines, which promotes the development of pDC in vitro along with FL, similar to in vivo niche.

Islets immunoisolation using encapsulation and PEGylation, simultaneously, as a novel design.

The most important obstacle in islets transplantation for the treatment of diabetes is graft rejection by the host immune system. To solve this problem, immunosuppressive drugs should be used, but they may have several side effects. To overcome these problems, islets immunoisolation systems such as encapsulation and PEGylation have been developed. The aim of this study was to investigate the possibility of using encapsulation and PEGylation techniques simultaneously (as a novel design) for immunocamouflaging the islets of Langerhans. For this purpose, the attachment of poly-L-ornithine (PLO) onto the surface of alginate microcapsules and activated methoxy polyethylene glycol (mPEG) onto alginate-PLO microcapsules was verified by Fourier transform infrared analysis and scanning electron microscopy. Viability of the free and encapsulated islets up to the 7th day was approved by acridine orange (AO)/propidium iodide (PI). The obtained results from lymphocytes co-culturing with free and encapsulated islets (in different designs of microcapsules with one to three layers) showed that encapsulation generally reduces the immune response against the islets. However, the addition of PLO and mPEG as second and third layers to the surface of alginate microcapsules decreased interleukine-2 (IL-2) secretion against the islets more and more. Finally, two different activated mPEG, mPEG-succinimidyl carbonate (mPEG-SC) and mPEG-succinimidylvaleric acid (mPEG-SVA), used separately on the surface of microcapsules were investigated, and the results showed that IL-2 secretion was reduced 14.3% and 37.5% in comparison with the alginate-PLO microcapsules, respectively. On the other hand, mPEG-SVA was more effective than mPEG-SC, so it decreased IL-2 secretion 27.1% more than mPEG-SC.

Optimization of monomethoxy poly(ethylene glycol) grafting on Langerhans islets capsule using response surface method.

Langerhans islet transplantation is a much less invasive approach compared with the pancreas transplantation to 'cure' diabetes. However, destruction of transplanted islets by the immune system is an impediment for a successful treatment. Chemical grafting of monomethoxy poly(ethylene glycol) onto pancreatic islet capsule is a novel approach in islet immunoisolation. The aim of this study was to determine an optimized condition for grafting of monomethoxy poly(ethylene glycol) succinimidyl propionate (mPEG-SPA) on islets capsule. Independent variables such as reaction time, the percentage of longer mPEG in the mixture, and polymer concentration were optimized using a three-factor, three-level Box-Behnken statistical design. The dependent variable was IL-2 (interleukin-2) secretion of lymphocytes co-cultured with PEGylated or uncoated control islets for 7 days co-culturing. A mathematical relationship is obtained which explained the main and quadratic effects and the interaction of factors which affected IL-2 secretion. Response surface methodology predicted the optimized values of reaction time, the percentage of longer mPEG in the mixture, and polymer concentration of 60 min to be 63.7% mPEG10 and 22 mg/mL, respectively, for the minimization of the secreted IL-2 as response. Islets which were PEGylated at this condition were transplanted to diabetic rats. The modified islets could survive for 24 days without the aid of any immunosuppressive drugs and it is the longest survival date reported so far. However, free islets (unmodified islets as control) are completely destroyed within 7 days. These results strongly suggest that this new protocol provides an effective clinical means of decreasing transplanted islet immunogenicity.

Targeted delivery of doxorubicin-utilizing chitosan nanoparticles surface-functionalized with anti-Her2 trastuzumab.

BACKGROUND: Targeting drugs to their sites of action to overcome the systemic side effects associated with most antineoplastic agents is still a major challenge in pharmaceutical research. In this study, the monoclonal antibody, trastuzumab, was used as a targeting agent in nanoparticles carrying the antitumor drug, doxorubicin, specifically to its site of action. METHODS: Chitosan-doxorubicin conjugation was carried out using succinic anhydride as a crosslinker. Trastuzumab was conjugated to self-assembled chitosan-doxorubin conjugate (CS-DOX) nanoparticles (particle size, 200 nm) via thiolation of lysine residues and subsequent linking of the resulted thiols to chitosan. Conjugation was confirmed by gel permeation chromatography, differential scanning calorimetry, Fourier transform infrared spectroscopy, and (1)H nuclear magnetic resonance spectroscopy studies. Dynamic light scattering, transmission electron microscopy, and zeta potential determination were used to characterize the nanoparticles. RESULTS: CS-DOX conjugated nanoparticles had a spherical shape and smooth surface with a narrow size distribution and core-shell structure. Increasing the ratio of doxorubicin to chitosan in the conjugation reaction gave rise to a higher doxorubicin content but lower conjugation efficiency. Trastuzumab-decorated nanoparticles (CS-DOX-mAb) contained 47 µg/mg doxorubicin and 33.5 µg/mg trastuzumab. Binding of trastuzumab to the nanoparticles was further probed thermodynamically by isothermal titration calorimetry. Fluorescence microscopy demonstrated enhanced and selective uptake of CS-DOX-mAb by Her2+ cancer cells compared with nontargeted CS-DOX nanoparticles and free drug. CONCLUSION: Antibody-conjugated nanoparticles were shown to discriminate between Her2+ and Her2⁻ cells, and thus have the potential to be used in active targeted drug delivery, with reduction of drug side effects in Her2+ breast and ovarian cancers.

Effect of molecular mass of methoxypoly(ethylene glycol) activated with succinimidyl carbonate on camouflaging pancreatic islets.

The surface modification of Langerhans islets by grafting activated poly(ethylene glycol) on to their capsules in order to prevent immune-system stimulation is a novel method in diabetes cell therapy. In the present study, mPEG [methoxypoly(ethylene glycol)] with two molecular masses of 5 and 10 kDa, activated with SC (succinimidyl carbonate), was grafted on to the surface of pancreatic islets at a polymer concentration of 22 mg/ml. It was found that PEGylated islets were viable and active, and no morphological changes on the collagen capsule of islets were observed. The amount of interleukin-2 secretion from lymphocytes co-cultured with islets PEGylated with mPEG-SC of 5 and 10 kDa was 112.12 ± 23.09 pg/ml and 172.75 ± 27.94 pg/ml respectively. Thus mPEG-SC (SC-activated mPEG) with higher molecular mass was more suitable for camouflaging islets from the immune system.

Optimization of PEGylation conditions for BSA nanoparticles using response surface methodology.

Chemical coupling of polyethylene glycol (PEG) to proteins or particles (PEGylation), prolongs their circulation half-life by greater than 50-fold, reduces their immunogenicity, and also promotes their accumulation in tumors due to enhanced permeability and retention effect. Herein, phase separation method was used to prepare bovine serum albumin (BSA) nanoparticles. PEGylation of BSA nanoparticles was performed by SPA activated mPEG through their free amino groups. Effect of process variables on PEGylation efficiency of BSA nanoparticles was investigated and optimized through response surface methodology with the amount of free amino groups as response. Optimum conditions was found to be 32.5 g/l of PEG concentration, PEG-nanoparticle incubation time of 10 min, incubation temperature of 27°C, and pH of 7 for 5 mg of BSA nanoparticles in 1 mL phosphate buffer. Analysis of data showed that PEG concentration had the most noticeable effect on the amount of PEGylated amino groups, but pH had the least. Mean diameter and zeta potential of PEGylated nanoparticles under these conditions were 217 nm and -14 mV, respectively. In conclusion, PEGylated nanoparticles demonstrated reduction of the negative surface charge compared to the non modified particles with the zeta potential of -31.7 mV. Drug release from PEGylated nanoparticles was almost slower than non-PEGylated ones, probably due to existence of a PEG layer around PEGylated particles which makes an extra resistance in opposition to drug diffusion.