Injectable nanospheres from a novel multiblock copolymer: cytocompatibility, degradation and in vitro release studies

The aim was to develop and characterize nanospheres made from a newly synthesized poly (D,L-lactide-co-ethyleneglycol) (-PLA-PEG-PLA-)n multiblock copolymer. Nanospheres were prepared under optimized conditions of modified emulsion-solvent evaporation technique in a continuous flow process using rhodamine B as a drug model. They were characterized for size distribution, zeta (zeta) potential, porosity and morphology. Drug loading and yield were also determined. In vitro degradation studies of the copolymer were conducted in phosphate buffer (pH 7.4) at 37 degrees C. The cytotoxic properties of the polymer and vector were analysed by dimethylthiazoldiphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays on the B16 mouse cell line. Release of rhodamine B from the nanospheres was assayed in vitro using a dialysis bag in isotonic phosphate buffer (pH 7.4) at 37 degrees C. Spherical and non-porous nanospheres with mean size less than 800 nm could be prepared. The (zeta) potential was neutral. The average yield was approximately 70% with 7% rhodamine loading. A total of 50% of the multiblock underwent initial degradation after 4 weeks, while degradation was complete after 16 weeks. Cellular proliferation was not inhibited as no cytotoxicity was observed with the copolymers and nanospheres. Rhodamine B was released in a stepwise pattern. The initial burst was 20%, and release was prolonged thereafter for 29 days. Thus, injectable nanospheres with prolonged rhodamine B release have been designed and characterized as a potential drug-delivery system.     

Prolonged Anti-Inflammatory Action of DL-Lactide/Glycolide Copolymer Nanospheres Containing Betamethasone Sodium Phosphate for an Intra-Articular Delivery System in Antigen-Induced Arthritic Rabbit

Purpose. The objective of the present study was to develop prolonged anti-inflammatory action of DL-lactide/glycolide copolymer (PLGA) nanosphere incorporating a water-soluble corticosteroid (betamethasone sodium phosphate; BSP). Another aim was to demonstrate the biocompatibility and biologic efficacy of these BSP-loaded nanospheres directly administered into ovalbumin-induced chronic synovitis in the rabbit. Methods. BSP-loaded nanospheres were prepared by an emulsion solvent diffusion method in oil (caprylate and caprate triglyceride). The drug releasing properties of the nanospheres were measured in vitro in phosphate buffer saline (PBS: pH7.4), and in vivo in rat air-pouch (pseudo synovial fluid). The BSP-loaded nanosphere suspensions were administered into the joint cavity in a model of antigen-induced arthritic rabbit and evaluated by measuring the joint swelling, and the biocompatibility was appraised by histologic microscopy. Results. The BSP-nanospheres were a unimodally-dispersed particulate system with a mean diameter ranging from 300 to 490 nm, and BSP was efficiently entrapped in the lipophilic copolymer (PLGA), although its hydrophilic properties. The drug release-rate from the nanospheres in PBS was controlled by the molecular weight and the lactic/glycolic acid (LA/GA) ratio of the polymers. The in vitro releasing study demonstrated that sustained drug release occurred for over three weeks. In the antigen-induced arthritic rabbit, the joint swelling decreased significantly by administering BSP-loaded nanospheres during a 21-day period after intra-articular challenge. With regards to the prolonged anti-inflammatory efficacy, serum antibody to ovalbumin showed a sustained reduction during the period, and the steroidal effect appeared by the degradation of the polymer in the synovium. The BSP-nanosphere administered was phagocytosed by the synovial activated-cells and the cartilage degradation was almost prevented. Conclusions. Direct intra-articular injection of a PLGA nanosphere system with a water-soluble steroid provided a prolonged pharmacological efficacy in the joints of arthritic rabbits. The local anesthetic in the knee-joints was evaluated to be safe and without biologic damage.     

Poly(l-lactide-co-glycolide) nanospheres conjugated with a nuclear localization signal for delivery of plasmid DNA

Polymeric nanospheres fabricated from biodegradable poly(lactide-co-glycolide) (PLGA) have been extensively investigated for applications in gene delivery. In this study, we show that the covalent conjugation of a nuclear localization signal (NLS, SV40 peptide) on PLGA nanospheres enhances the gene transfection efficiency. NLS conjugated PLGA copolymer was prepared by using a coupling reaction between maleimide-terminated PLGA copolymer and NLS in the presence of Imject maleimide conjugation buffer. PLGA nanospheres encapsulating plasmid (pDNA) were prepared by using a double emulsion-solvent evaporation method. The kinetics of in vitro release of pDNA from PLGA nanospheres was determined with UV in phosphate buffered saline (PBS). Gene transfection efficiency in human dermal fibroblasts was tested in vitro using nanospheres encapsulating the luciferase gene. The conjugation of the NLS peptide to the PLGA nanospheres could improve the nuclear localization and/or cellular uptake of PLGA nanosphere/pDNA constructs and thereby improve the transfection efficiency of a PLGA nanosphere gene delivery system. The pDNA was released from PLGA nanospheres over nine days. NLS conjugation enhanced the gene transfection efficiency in vitro by 1.2 ～ 3.2-fold over 13 days. PLGA/pDNA nanospheres appeared to be superior to PEI/pDNA complexes for the long-term expression of pDNA. Furthermore, the level of the sustained gene expression of the PLGA nanospheres was enhanced by the conjugation of NLS to the PLGA nanospheres. This study showed that the NLS conjugation enhanced the gene transfection efficiency of the PLGA nanosphere gene delivery system in vitro and that the enhanced gene expression was sustained for at least 13 days.     

Spray coating of foley urinary catheter by chlorhexidine-loadedpoly(ε-caprolactone) nanospheres: effect of lyoprotectants,characteristics, and antibacterial activity evaluation

In this study, chlorhexidine-loaded poly(ε-caprolactone) nanospheres (CHX-NS) were prepared and successfully coated on the urinary catheters. Properties of CHX-NS were evaluated including drug loading content and the nanosphere size. Effects of different lyoprotectants for long-term storage of CHX-NS were also investigated. In vitro release study and antibacterial activity were also conducted using 20 cycles coated-urinary catheters. Results showed that the high-pressure emulsification-solvent evaporation technique provided the drug loading content at 1.14?±?0.16% and the size of nanospheres was 152?±?37?nm. The suitable lyoprotectant for long-term storage of CHX-NS was sucrose which provided noticeably no aggregation at the degree of reconstitution at 89.95%. The amount of CHX loading on coated catheters was at 4.55?±?0.31?mg. Drug release from the coated catheters in artificial urine could be prolonged up to 2 weeks and bacteria proliferation was inhibited up to 14?days. These results suggest that the antimicrobial activity of CHX-NS reduces the adherence of the uropathogens to the catheter surface. Chlorhexidine-loaded polymeric nanospheres were fabricated which can be successfully coated on urinary catheters. These systems have potential use for prolonged antimicrobial applications.     

Ocular tolerability and in vivo bioavailability of poly(ethylene glycol) (PEG)-coated polyethyl-2-cyanoacrylate nanosphere-encapsulated acyclovir

Acyclovir-loaded polyethyl-2-cyanoacrylate (PECA) nanospheres were prepared by an emulsion polymerization process in the micellar phase and characterized. The influence of the presence of nonionic surfactant as well as other substances [i.e., 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CyD) and poly(ethylene glycol) (PEG)], on formulation parameters and loading capacity was investigated. In particular, the presence of PEG resulted in an increase of mean size and size distribution. To obtain PEG-coated PECA nanospheres with a mean size of < 200 nm, Pluronic F68 at concentrations > 1.5% (w/v) should be used during preparation. The presence of PEG also resulted in a change in zeta potential, from -25.9 mV for uncoated nanospheres to -12.2 mV for PEG-coated PECA nanospheres. The presence of HP-beta-CyD elicited an increase of nanosphere size and size distribution, but zeta potential was not influenced. In vitro drug release from nanospheres was determined in both phosphate buffer (pH 7.4) and plasma. The presence of HP-beta-CyD and PEG did not influence the acyclovir release rate in plasma. In the case of release in phosphate buffer, PEG-coated nanospheres showed a slower release. Ocular tolerability of PEG-coated PECA nanospheres was evaluated by the in vivo Draize test. This colloidal carrier was well tolerated, eliciting no particular inflammation at the level of the various ocular structures. In vivo ocular bioavailability was evaluated by instilling 50 microL of the acyclovir-loaded nanospheres only once in the conjunctival sac of rabbit eyes. At various time intervals, aqueous humour acyclovir content was determined by high-performance liquid chromatography. Acyclovir-loaded PEG-coated PECA nanospheres were compared with an aqueous solution of the drug and a physical mixture of acyclovir nanospheres. The acyclovir-loaded PEG-coated PECA nanospheres showed a significant (p < 0.001) increase of drug levels (25-fold) in aqueous humor compared with the free drug or the physical mixture. This finding is probably due to an improved ocular mucoadhesion of PEG-coated PECA nanospheres.     

Preparation of Sub-100 nm Human Serum Albumin Nanospheres Using a pH-Coacervation Method

Abstract

Human serum albumin (HSA) nanospheres of about 100 nm diameter were prepared using a pH-coacervation method whereby acetone was added to an HSA solution (pH 9.0). The particles obtained were cross-linked by glutaraldehyde. Increasing the pH of the HSA solution resulted in a gradual rise in the particle size of the resultant nanospheres. A higher cross-linking efficiency was obtained with increased glutaraldehyde concentration and cross-linking time. No significant differences in surface properties, as determined by zeta potential measurements, were recorded between particles prepared from HSA solutions with different pH. The nanospheres were quite stable over 4 days in both phosphate buffer saline (PBS) solution (pH 7.4) and rat serum, but degraded rapidly over 6 hours when incubated in PBS solution containing trypsin.     

Preparation and optimization of chlorophene-loaded nanospheres as controlled release antimicrobial delivery systems

Chlorophene-loaded nanospheres with various formulation parameters were evaluated. The optimal formulation was found at 0.1% w/v of poloxamer 407, 15?mL of ethyl acetate and 20% initial chlorophene loading that provided the suitable size (179?nm), the highest loading content (19.2%), encapsulation efficiency (88.0%) and yield (91.6%). Moreover, encapsulation of chlorophene in nanospheres was able to prolong and sustain drug release over one month. Chlorophene-loaded nanospheres were effective against Staphylococcus aureus (S. aureus) and Candida albicans (C. albicans), the main cause of hospital-acquired infections. Chlorophene-loaded nanospheres were effective against S. aureus (>46?µg/mL) and C. albicans (>184?µg/mL). These nanospheres appeared to have profound effect on the time-dependent hemolytic activity due to gradual release of chlorophene. At the concentration of 46?µg/mL, nearly no HRBC hemolysis in 24?h compared to 80% of hemolysis from free drug. In conclusion, polymeric nanospheres were successfully fabricated to encapsulate chlorophene which can eliminate inherent toxicity of drugs and have potential uses in prolonged release of antimicrobial.     

Mucoadhesive and floating chitosan-coated alginate beads for the controlled gastric release of amoxicillin

This work focused on the development of mucoadhesive and floating chitosan-coated alginate beads as a gastroretensive delivery vehicle for amoxicillin, towards the effective eradication of Helicobacter pylori, a major causative agent of peptic ulcers. Alginate was used as the core bead core polymer and chitosan as the mucoadhesive polymer coating. Amoxicillin-loaded alginate beads coated with 0.5% (w/v) chitosan (ALG/0.5%CHI) exhibited excellent floating ability, high encapsulation efficiency, high drug loading capacity, and a strong in vitro mucoadhesion to the gastric mucosal layer. In vitro, amoxicillin was released faster in simulated gastric fluid (pH 1.2, HCl) than in simulated intestinal fluid (phosphate buffer, pH 7.4). ALG/0.5%CHI could be prepared with a > 90% drug encapsulation efficiency and exhibited more than 90% muco-adhesiveness, 100% floating ability, and achieved sustained release of amoxicillin for over six hours in SGF.     

Modification of the Copolymers Poloxamer 407 and Poloxamine 908 can Affect the Physical and Biological Properties of Surface Modified Nanospheres

Purpose. To investigate the effects of the modification of the copolymers poloxamer 407 and poloxamine 908 on the physical and biological properties surface modified polystyrene nanospheres. Methods. A method to modify poloxamer 407 and poloxamine 908, introducing a terminal amine group to each PEO chain has been developed. The aminated copolymers can be subsequently radiolabelled with lodinated (I¹²⁵) Bolton-Hunter reagent. The aminated copolymers were used to surface modify polystyrene nanospheres. The physical and biological properties of the coated nanospheres were studied using particle size, zeta potential, in vitro non-parenchymal cell uptake and in vivo biodistribution experiments. Results. The presence of protonated amine groups in the modified copolymers significantly affected the physical and biological properties of the resulting nanospheres, although the effects were copolymer specific. The protonated surface amine groups in both copolymers reduced the negative zeta potential of the nanospheres. Acetylation of the copolymer's free amine groups resulted in the production of nanospheres with comparable physical properties to control unmodified copolymer coated nanospheres. In vivo, the protonated amine groups in the copolymers increased the removal of the nanospheres by the liver and spleen, although these effects were more pronounced with the modified poloxamer 407 coated nanospheres. Acetylation of the amine groups improved the blood circulation time of the nanospheres providing modified poloxamine 908 coated nanospheres with comparable biological properties to control poloxamine 908 coated nanospheres. Similarly, modified poloxamer 407 coated nanospheres had only slightly reduced circulation times in comparison to control nanospheres. Conclusions. The experiments have demonstrated the importance of copolymer structure on the biological properties of surface modified nanospheres. Modified copolymers, which possess comparable properties to their unmodified forms, could be used in nanosphere systems where antibody fragments can be attached to the copolymers, thereby producing nanospheres which target to specific body sites.     

Controlled release of vancomycin from biodegradable microcapsules

Poly D,L-lactic acid (PLA) and its copolymers with glycolide PLGA 90:10 and 70:30 were polymerized under various conditions to yield polymers in the molecular weight range 12000-40000 daltons, as determined by gel permeation chromatography. Vancomycin hydrochloride was the hydrophilic drug of choice for the treatment of methicillin resistant Staphyloccoccal infections. It was microencapsulated in the synthesized polymers using water-oil-water (w/o/w) double emulsion and solvent evaporation. The influence of microcapsule preparation medium on product properties was investigated. An increase in polymer-to-drug ratio from 1:1 to 3:1 caused an increase in the encapsulation efficiency (i.e. from 44-97% with PLGA). An increase in the emulsifier (PVA) molecular weight from 14-72 kD caused an increase in encapsulation efficiency and microcapsule size. The in vitro release of vancomycin from microcapsules in phosphate buffer saline (pH 7.4) was found to be dependent on molecular weight and copolymer type. The kinetic behaviour was controlled by both diffusion and degradation. Sterilization with ⁶⁰Co (2.5 Mrad) also affected the degradation rate and release profiles. Degradation of microcapsules could be seen by scanning electron microscopy, by the increase in the release rate from PLA and by the decrease in the T_g values of microcapsules. In vitro bactericidal effects of the microcapsule formulations on S.aureus were determined with a special diffusion cell after the preparations had been sterilized, and were found to have bactericidal effects lasting for 4 days.     

Sustained Local Anesthetic Release from Bioerodible Polymer Matrices: A Potential Method for Prolonged Regional Anesthesia

Polyanhydride polymer matrices have been used successfully for sustained release of a number of drugs in vitro and in vivo. Dibucaine free base, dibucaine HC1, and bupivacaine HC1 were incorporated into polymer matrices with copolymer l,3-bis(p-carboxyphenoxy)propane-sebacic acid anhydride (1:4). Drug release was measured in vitro following incubation of the drug-polymer matrices in phosphate buffered solution, pH 7.4, at 37°C, to approximate in vivo conditions. Local anesthetics were released in a sustained manner yielding 90% cumulative drug release over periods ranging from 3 to 14 days. The kinetics of release varied with both the choice of local anesthetic and the method of drug incorporation into the matrix (hot melt versus compression molding). Polymer local anesthetic matrix devices (PLAM), loaded by hot melt incorporation with 20% bupivacaine, were implanted in vivo adjacent to the sciatic nerve in three rats. Reversible neural blockade was observed for 4 days in all animals. Polymer implants without local anesthetic showed no neural blockade. This technology could lead to methods of prolonged blockade of peripheral nerves or of sympathetic ganglia, which may be utilized for the management of postoperative pain, sympathetically maintained pain, or certain forms of chronic pain.     

Hydrolytic Stability of Alkyl 1H-Benzotriazolecarboxylates

Hydrolysis of 1H-benzotriazolecarboxylates was studied in 0.1 M NaOH, phosphate buffer pH 7.4 and using a microsomal esterase preparation. Results obtained for the alkaline hydrolysis qualitatively resembled those of enzymatic hydrolysis. In phosphate buffer pH 7.4 the esters were sufficiently stable concerning their use as potential substrates for in vitro biotransformation studies.     

Controlled Gene Delivery System Based on Thermosensitive Biodegradable Hydrogel

Purpose. Currently, most pDNA delivery systems based on synthetic polymers are either nonbiodegradable or not sensitive to the release environment. The primary objective of this study was to develop and evaluate an aqueous-based, thermosensitive, biodegradable and biocompatible triblock copolymer to control pDNA delivery in vitro and in vivo. Methods. The triblock copolymers, poly[ethylene glycol-b-(D, L-lactic acid-co-glycol acid)-b-ethylene glycol] (PEG-PLGA-PEG), were synthesized as previously described. The molecular weight and polydispersity of PEG-PLGA-PEG were monitored by gel permeation chromatography (GPC). The cytotoxicity of PEG-PLGA-PEG was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetra- zolium bromide assay. The release of ³²P-labeled pDNA entrapped in aqueous dispersion of PEG-PLGA-PEG in 0.1 mol/L sodium phosphate buffer solution (pH 7.4) was studied at 37°C under agitation. Gene transfection efficiency was evaluated in a skin wound model in CD-1 mice. Results. The aqueous dispersion of PEG-PLGA-PEG flows freely at room temperature but form a gel at 37°C body temperature. The in vitro degradation of PEG-PLGA-PEG lasted for more than 30 days. The cytotoxicity of PEG-PLGA-PEG evaluated in HEK 293 cells was significantly lower than that of poly-L-lysine hydrochloride. The release profile of supercoiled pDNA from the polymer followed the zero-order kinetics up to 12 days. Maximal gene expression of luciferase was at 24 h in the skin wound of CD-1 mice and by 72 h, the expression dropped by nearly 94%. Conclusions. These results suggest hydrogel formed by PEG-PLGA-PEG could be a promising platform for delivery of pDNA, which represents a novel strategy that may serve as a non-viral vector for gene therapy in wound healing.     

A supercritical fluid-based coating technology. 3: Preparation and characterization of bovine serum albumin particles coated with lipids

Solvent-free microparticles, loaded with bovine serum albumin as a model protein, were produced using a novel supercritical (SC) fluid-based coating technology. Coating material consists either of trimyristin (Dynasan® 114) or of Gelucire® 50-02. Microparticles obtained were characterized as regards their morphology, protein content and in vitro release profile. A discontinuous coating made of micro-needles of trimyristin led to an initial burst release of ～ 70% in 30min. However, a prolonged release of the BSA could be achieved in a phosphate buffer solution at 37 °C over a 24 h period from particles coated with Gelucire® 50-02. Furthermore, it was shown that BSA does not undergo any degradation after SC CO₂ treatment under the conditions used in the coating process.     

Development,characterization and cancer targeting potential of surface engineered carbon nanotubes

Abstract

The aim of the present study was to assess the in vitro and in vivo potential of doxorubicin-loaded, folic acid appended engineered multi-walled carbon nanotubes (DOX/FA-PEG-MWCNTs) for efficient tumor targeting. The loading efficiency was determined to be 92.0?±?0.92 (DOX/FA-PEG-MWCNTs) in phosphate buffer solution (pH 7.4) ascribed to π–π stacking interaction. The developed nanoconjugates were evaluated for in vitro DOX release, erythrocytes toxicity, ex vivo cytotoxicity and cell uptake studies on MCF-7 (breast cancer cell line). The DOX/FA-PEG-MWCNTs nanoconjugate affords higher efficacy in tumor growth suppression due to its stealth nature and most preferentially taken up by the cultured MCF-7 through caveolae-mediated endocytosis as compared to free DOX. The in vivo studies were performed to determine the pharmacokinetics, biodistribution and antitumor efficacy on tumor bearing female Sprague Dawley rats and improved pharmacokinetics confirm the function of FA-PEG conjugated CNTs. The median survival time for tumor bearing rats treated with DOX/FA-PEG-MWCNTs (30?d) was extended very significantly as compared to free DOX (p?<?0.001). The results concluded that developed water-soluble nano-conjugates might emerge as “safe and effective” nano-medicine in cancer treatment by minimizing the side effects with and Generally Regarded as Safe prominence.     

Improved pharmacokinetics and antihyperlipidemic efficacy of rosuvastatin-loaded nanostructured lipid carriers

In the present study, rosuvastatin calcium-loaded nanostructured lipid carriers were developed and optimized for improved efficacy. The ROS-Ca-loaded NLC was prepared using melt emulsification ultrasonication technique and optimized by Box–Behnken statistical design. The optimized NLC composed of glyceryl monostearate (solid lipid) and capmul MCM EP (liquid lipid) as lipid phase (3% w/v), poloxamer 188 (1%) and tween 80 (1%) as surfactant. The mean particle size, polydispersity index (PDI), zeta potential (ζ) and entrapment efficiency (%) of optimized NLC formulation was observed to be 150.3?±?4.67?nm, 0.175?±?0.022, ?32.9?±?1.36?mV and 84.95?±?5.63%, respectively. NLC formulation showed better in vitro release in simulated intestinal fluid (pH 6.8) than API suspension. Confocal laser scanning showed deeper permeation of formulation across rat intestine compared to rhodamine B dye solution. Pharmacokinetic study on female albino Wistar rats showed 5.4-fold increase in relative bioavailability with NLC compared to API suspension. Optimized NLC formulation also showed significant (p?<?0.01) lipid lowering effect in hyperlipidemic rats. Therefore, NLC represents a great potential for improved efficacy of ROS-Ca after oral administration.     

Colon specific CODES based Piroxicam tablet for colon targeting: statistical optimization,in vivo roentgenography and stability assessment

Abstract

This study was aimed to statistically optimize CODES? based Piroxicam (PXM) tablet for colon targeting. A 3² full factorial design was used for preparation of core tablet that was subsequently coated to get CODES? based tablet. The experimental design of core tablets comprised of two independent variables: amount of lactulose and PEG 6000, each at three different levels and the dependent variable was %CDR at 12?h. The core tablets were evaluated for pharmacopoeial and non-pharmacopoeial test and coated with optimized levels of Eudragit E100 followed by HPMC K15 and finally with Eudragit S100. The in vitro drug release study of F1–F9 was carried out by change over media method (0.1?N HCl buffer, pH 1.2, phosphate buffer, pH 7.4 and phosphate buffer, pH 6.8 with enzyme β-galactosidase 120?IU) to select optimized formulation F9 that was subjected to in vivo roentgenography. Roentgenography study corroborated the in vitro performance, thus providing the proof of concept. The experimental design was validated by extra check point formulation and Diffuse Reflectance Spectroscopy revealed absence of any interaction between drug and formulation excipients. The shelf life of F9 was deduced as 12 months. Conclusively, colon targeted CODES? technology based PXM tablets were successfully optimized and its potential of colon targeting was validated by roentgenography.     

Development of Biodegradable Nanoparticles for Oral Delivery of Ellagic Acid and Evaluation of Their Antioxidant Efficacy Against Cyclosporine A-Induced Nephrotoxicity in Rats

Purpose Ellagic acid (EA), a dietary antioxidant associated with poor biopharmaceutical properties, was encapsulated into poly(lactide-co-glycolide) (PLGA) and polycaprolactone (PCL) nanoparticles to improve oral bioavailability. Materials and Methods EA-loaded nanoparticles were prepared following emulsion–diffusion–evaporation method employing didodecyldimethyl ammonium bromide (DMAB) and polyvinyl alcohol (PVA) as stabilizers. In vitro release was investigated in phosphate buffer (pH 7.4). The in situ permeation studies were performed in rats. The antioxidant potential of the DMAB-stabilized nanoparticulate formulations was evaluated against cyclosporine A (CyA)-induced nephrotoxicity in rats. Results EA-loaded PLGA and PCL nanoparticles have been succesfully prepared employing PEG 400 as co-solvent to solubilize EA. The stabilizers influenced the particle size and encapsulation efficiency. DMAB when used as stabilizer to particles of ~120 nm and ~50% encapsulation, whereas PVA led to ~290 nm and ~60% encapsulation at 5% initial loading (w/w of polymer). The in vitro release of EA from the nanoparticles followed Higuchi's square root pattern and was faster with PVA-stabilized particles in comparison to those stabilized with DMAB. From the in situ permeation studies in rats, it was evident that intestinal uptake of EA as DMAB-stabilized nanoparticles was significantly higher as compared to the sodium carboxymethyl cellulose suspension and the PVA-stabilized particles. EA and EA nanoparticles were able to prevent the CyA-induced nephrotoxicity in rats as evident by biochemical parameters as well as kidney histopathology. Conclusion The present study demonstrates the potential of EA nanoparticulate formulations in the prevention of CyA-induced nephrotoxicity at three times lower dose suggesting improved oral bioavailability of EA. This paper is dedicated to Ramesh C. Gupta, Professor and Agnes Brown Duggan Chair in Oncological Research, University of Louisville, US, who inspired me with his scientific approach, honesty and human warmth.     

Genkwanin nanosuspensions: a novel and potential antitumor drug in breast carcinoma therapy

Recently, genkwanin (GKA) has been shown to display in vitro antitumor activity against some cancer cells, but its poor solubility restricted the in vivo study and further investigation of its antitumor therapeutic efficacy. In this paper, genkwanin nanosuspensions (GKA-NSps) were successfully prepared using D-alpha tocopherol acid polyethylene glycol succinate (TPGS) as a stabilizer using the precipitation-homogenization method. The obtained GKA-NSps had an average particle size of 183.1?±?4.4?nm, a PDI value of 0.16?±?0.07, a zeta potential of ?16.2?±?0.1?mV, and a drug loading content of 49.36?±?0.14%. GKA-NSps showed spherical morphology and very good stability in normal saline, phosphate buffer saline (PBS, pH 7.4), 5% glucose, artificial gastric juice, artificial intestinal juice and plasma; thus, it is suitable for both oral and intravenous administration. The resultant GKA-NSps displayed sustained drug release behavior and stronger in vitro cytotoxicity against 4T1, MCF-7, MDA-MB-453, HeLa, HepG2, BT474, and A549 cells than free GKA. The in vivo study in MCF-7 tumor-bearing nude mice indicated that GKA-NSps (60?mg/kg, i.v.) achieved similar therapeutic efficacy as PTX injection (8?mg/kg, i.v.) (62.09% vs. 61.27%), while the minimal lethal dose was more than 320?mg/kg, indicating good safety. By using nanotechnology, our study suggested that some antitumor flavonoids of low potency, such as GKA, are promising as safe but effective anticancer drugs.     

Preparation and characteristics of chitosan microspheres in different acetylation as drug carrier system

Chitosan microspheres (CM) and reacetylated chitosan microspheres (ACM) were successfully made by the methods of oil/water emulsification and acetic anhydride. The characteristics of the microspheres as a drug carrier system were investigated. Two microsphere samples had spherical shape with the mean diameter of 80.79 µm for CM and 81.25 µm for ACM. The in vitro degradation (pH 7.4) in the presence of lysozyme showed a slow mass loss and ACM was higher degradation compared to CM. The microspheres, especially ACM, had a high drug loading capacity of Adriamycin hydrochloride (ADM) (12.4%) and had sustained release. The cytotoxicity was evaluated in vitro via MTT assay, ACM with steadily continual adhesion to cells had no fibroblast cytotoxicity. The inhibitory rates of ADM-loading CM, ACM suspension to Tca 8113 cells were significantly outperformed that of ADM solution.