PLGA Nanospheres Research Articles

AB0175 INNOVATIVE PREPARATION OF CURCUMIN NANOPARTICLES TO IMPROVE ANTI-INFLAMMATORY EFFECT IN RHEUMATIC DISEASE

Background:Curcumin (Cur) as a natural compound can be used in the wide spectrum of healthy functions and pharmacological activities [1-4]. It shows great promise for medication of various pro-inflammatory chronic illnesses [5]. In this study, we evaluate the ability of poly(lactide-co-glycolide)(PLGA) and different grads of PVA (polyvinyl alcohol) and lecithin as a drug delivery system for poorly soluble CurObjectives:The goal of this study was to prepare and characterize Cur encapsulated PLGA and different grads of PVA and lecithin as an efficient nanocarrier for improve anti-inflammatory effect in rheumatic diseaseMethods:The PLGA nanospheres were formulated and then characterized for percent yield, encapsulation efficiency, surface morphology, and in vitro drug release profiles. At first, 6 mg of Cur was added to the organic phase including 24 mg of polymer dissolved in 5 mL of dichloromethane to constitute 1:4 (drug-to-polymer) ratios. Then, a mixture of PVA-lecithin (at about 5 cc) was added to maintain the stability of double emulsion droplets. The emulsion was continuously stirred at 300 rpm for 24 hours (at temperature of 37.5 ˚C) to evaporate the solvent, leaving behind the colloidal suspension of the drug-encapsulated nanoparticle in aqueous phase. The encapsulation of Cur into PLGA was characterized by Fourier transform infrared spectroscopy (FT-IR) and Transmission electron microscopy (TEM).Results:Our studies achieved the successful formation of smooth surface and spherical shape Cur encapsulated into PLGA nanoparticles by the TEM image confirmed. The particle size distribution demonstrated a range of 30 nm to 100 nm, with the mean particle size being 45 nm. FTIR study implies successful loading of Cur into the nanoparticles. We show high drug-loading efficiency about 98 ± 0.5% for 6% of Cur weight in total ingredients weight of PLGA (w/w). It was also seen that a slower sustained release of 10% CUR in 48 hours is observed with biocompatible PLGA in phosphate buffered saline (pH = 7.4). The MTT assay of the Cur-PLGA exhibited no cytotoxic effect on Normal mouse fibroblast cells (L-929) cell line. IC50 of Cur -PLGA increased 99.5% against Cur nanoparticles (33.57 ±0.62 µM) (P < 0.05).Conclusion:In this study, we constructed a novel preparation of curcumin nanoparticles with PLGA and different grads of PVA (polyvinyl alcohol) and lecithin to improve the bioavailability of CUR and PLGA exhibited no cytotoxic effect on L-929 cell line

Poly(lactic-co-glycolic acid)/Polyethylenimine Nanocarriers for Direct Genetic Reprogramming of MicroRNA Targeting Cardiac Fibroblasts

Cardiovascular disease remains a major cause of deaths globally. Post-heart-infarction, the most abundant cell type of heart, ‘fibroblasts’ undergoes a series of culminating events that lead to fibrotic scar tissue. In many organisms, injury to the heart can be restored but the adult human heart is unable to efficiently regenerate after ischemic injury. So, the inefficiency of heart to regenerate on its own after ischemic injury accounts for its reprogramming. Herein, we demonstrate the effect of microRNAs encapsulating Poly (lactic-co-glycolic acid) (PLGA)-Polyethylenimine (PEI) nanocarriers for direct reprogramming of cardiac fibroblast to cardiomyocyte-like cells. Dual, cardiac muscle specific miRNA (miR-1 and miR-133a) polyplexes were encapsulated in biodegradable PLGA nanospheres. Cytocompatibility of the nanocomplexes were evaluated by various in vitro assays, confirming their safety profile. The change in cardiac fibroblast phenotype to cardiomyocyte was identified by the expression of late-stage s...

Mitochondria-targeted nanospheres with deep tumor penetration for photo/starvation therapy.

Tumor masses are three-dimensional (3D). The abnormal physiology of solid tumors is a great barrier to anticancer drug delivery, and the development of effective therapeutic strategies for cancer treatment remains highly challenging. In this study, we have rationally designed IR780 and glucose oxidase (GOx) based poly lactic-co-glycolic acid (PLGA) nanospheres, which can not only selectively accumulate in mitochondria, but also penetrate into 3D tumors deeply at the same time, achieving synergistic treatment of phototherapy and enzyme (GOx)-induced starvation therapy under dual-imaging guidance/monitoring. The lipophilic cationic properties of IR780 enable the nanospheres to penetrate into deep tumor tissues, which has been demonstrated by in vitro 3D tumor modeling and in vivo tumor reconstruction. Meanwhile, the inherent structure of IR780 endows the nanospheres with mitochondrial targeting capability. As mitochondria are susceptible to hyperpyrexia and reactive oxygen species (ROS), mitochondria-targeted phototherapy shows more efficient therapeutic performance. Furthermore, the starvation effect of GOx can cut off the nutrition supply to tumor cells, enhancing the energy metabolism disorder of tumor cells after mitochondrial damage induced by phototherapy, further increasing the damage to tumor cells. In addition, the therapeutic process can be guided/monitored by photoacoustic (PA) and fluorescence (FL) dual imaging. Due to the incorporation of multiple modalities, these nanospheres are promising for cancer theranostics.

Poly(d,l-lactide-co-glycolide) nanospheres within composite poly(vinyl alcohol)/aloe vera electrospun nanofiber as a novel wound dressing for controlled release of drug

In this paper, poly(d,l-lactide-co-glycolide) (PLGA) nanospheres loading with a protein drug were incorporated in poly(vinyl alcohol)/Aloe vera (PVA/AV) nanofibers by electrospinning as a novel wound dressing. The influence of AV and PLGA nanospheres on the physical characteristics, antibacterial activity, and drug release behavior of the composite nanofibers were studied. A successful composite nanofiber production was observed by scanning electron microscopy. The release behavior showed a prolonged release with the addition of PLGA nanospheres. Antimicrobial activities against Staphylococcus aureus and Escherichia coli were found with AV content. The results indicated that the PVA/AV/PLGA nanofibers warrant further attention for wound-healing applications.

Spray coating of dual antibiotic-loaded nanospheres on orthopedic implant for prolonged release and enhanced antibacterial activity

Schanz pins are orthopedic implants that are used for the fixation of external fractures. Long-term use of Schanz pins may cause infection, bacterial adhesion, and biofilm formation, and it can also lead to implant rejection. The spray coating or dip coating of an antibiotic directly onto the surface of the implants prior to use is limited to the rapid release of antibiotic for only a short time. To overcome this problem, nanospheres, which are a type of drug-delivery system, were used to control the release of antibiotics. In this research, vancomycin and gentamicin were loaded separately in Poly(lactide-co-glycolide) (PLGA) nanospheres. Nanospheres were prepared by the double-emulsion solvent evaporation method and spray-coated onto the pins. These nanospheres were characterized in terms of size, zeta potential, drug loading, and encapsulation efficiency. The release profiles of antibiotic-loaded nanospheres were determined before investigating the in vitro release of antibiotics from the nanosphere-coated pins. Vancomycin-loaded PLGA nanospheres (VCM-NPs) and gentamicin-loaded PLGA nanospheres (GM-NPs) indicated slightly negative charges, and the sizes were 214.70 and 499.30 nm in diameter, respectively. VCM-NPs and GM-NPs displayed drug-loading contents of 7.12% and 7.97%, respectively. The concentration of vancomycin and gentamicin released from the coated pins were higher than the minimum inhibitory concentration of Staphylococcus aureus ATCC 25423 and Escherichia coli ATCC 25922 which could be sustained release for 42 and 49 days, respectively. The coated pins demonstrated superior biocompatibility and long-term antibacterial activity. Furthermore, the strategy utilizes dual antibiotic coating onto the implants via loading in polymeric nanospheres for enhanced antibacterial activity. The data gathered from this study is promising and is capable of combating implant associated infections. Hence, we suggest the use of this strategy for coating other medical devices.

Dual drug loaded PLGA nanospheres for synergistic efficacy in breast cancer therapy

Improved therapeutic effects can be achieved by the delivery of combination of drugs through multifunctional cell targeted nanocarrier systems. The present investigation reports the preparation of Poly (D,L-lactic-co-glycolic acid) (PLGA) nanospheres loaded with the novel combination such as Rutin (R) and Benzamide (B) as drugs using water-oil-water (w/o/w) emulsion method. Dual drug loaded PLGA nanospheres (R/B@PLGA) were stabilized by poly (vinyl alcohol) (PVA) coating and characterized in terms of morphology, size, surface charge, and structural chemistry by Scanning electron microscopy (SEM), Dynamic light scattering (DLS), Zeta potential analysis, UV–vis and Fourier transform infrared (FT-IR) spectroscopy. The inhibitory effects of rutin and benzamide on MDA-MB-231 (triple negative breast cancer-TNBC) cells using the drug loaded PLGA nanospheres as well as their non-toxic features were evaluated in vivo. The anticancer activity of the R/B@PLGA nanospheres through cell cycle disruption and apoptotic induction was assessed in vitro by flow cytometry analysis. Further, the in vitro antioxidant capacity, pH-based drug release and hemocompatible property were also investigated. It was shown that the R/B@PLGA nanospheres lacked genotoxic potential and they did not alter the antioxidant enzyme activities and histological features of zebrafish. Hence, this dual drug delivery system (DDS) not only actively targets multidrug-resistance (MDR) associated phenotype but also improves the therapeutic efficiency by its non-toxic nature towards enhanced cancer cell focused delivery and sustained release of therapeutic agents.

Preparation and characterization of atrazine-loaded biodegradable PLGA nanospheres

Atrazine is the second mostly used herbicide in USA, but low utilization ratio causes severe environmental problem, so controlled release system is highly needed in order to minimize the negative impact on environment. In this paper, a herbicide delivery system, atrazine-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) were prepared by forming an oilin-water emulsion using the emulsion-solvent evaporation method. By varying the preparation conditions of PLGA-NPs, such as sonication time, surfactant content, solvent fraction, and polymer content, the particle sizes of the PLGA-NPs were well controlled from 204 to 520 nm. The morphology and size distribution of PLGA-NPs were evaluated using dynamic light scattering (DLS) and scanning electron microscopy (SEM). Both the encapsulation efficiency and release profile of the herbicide from the PLGA-NPs were typically evaluated by using 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine (atrazine, ATZ) as the model. ATZ encapsulation efficiency within the PLGA-NPs was ranged from 31.6 to 50.5%. The release profiles of ATZ-loaded PLGA-NPs exhibited a much slower release rate in comparison with that of pure herbicide. The results demonstrated that the prepared PLGA-NPs had a high encapsulation efficiency and slow release rate, which could be used as a promising herbicide release system in agriculture to diminish the impact on the environment and minimize the potential harm to the farmers.

A novel synthesis of selenium nanoparticles encapsulated PLGA nanospheres with curcumin molecules for the inhibition of amyloid β aggregation in Alzheimer's disease

The main factors of Alzheimer's disease (AD) are the cerebral accumulation and the formation of extracellular amyloid plaques. The Aβ peptides are highly able to accumulative and produce fibrils that are placed to form these plaques in the AD. The biological action and drug delivery properties of curcumin (Cur) nanoformulation in the Alzheimer's disease therapeutics can be developed by the altering surface of the Poly-lactide-co-glycolide (PLGA) polymer and encapsulation of selenium nanoparticles (Se NPs). The morphological structure, size distributions of nanospheres, chemical interactions between the polymer and nanoformulations of synthesized curcumin and Se NPs loaded PLGA nanospheres have been studied by using the techniques of analytical instruments. The microscopic and nano observation results of synthesized Cur loaded nanospheres are exhibited that the mono-dispersed distributions of particles with spherical shaped structure. The present drug delivery system of Cur loaded Se-PLGA nanospheres could be decreases the amyloid-β load in the brains samples of AD mice, and greatly cured the memory deficiency of the model mice. The specific binding of Cur loaded Se-PLGA nanospheres with Aβ plaques were visualized by fluorescence microscopic technique. Se-PLGA targeting delivery system to amyloid plaques might be providing the enhanced therapeutic efficacy in AD lesions, which was studied by using transgenic mice (5XFAD). In conclusion, Cur loaded Se-PLGA nanoformulation has been demonstrated that valued delivery system for the targeted delivery and effective way to treat AD.

Robust mucosal and systemic responses against HTLV-1 by delivery of multi-epitope vaccine in PLGA nanoparticles

In this investigation, the immunogenicity of HTLV-1 fusion epitope-loaded PLGA nanoparticles (NPs) was assessed in the absence or presence of co-encapsulated CpG ODN adjuvant, in a mice model. For this purpose, the multi-epitope chimera including Tax, env, and gag immunodominant HTLV-1 epitopes was encapsulated in biodegradable PLGA NPs with or without CpG adjuvant. PLGA nanospheres produced by a double emulsion method had a size of <200 nm, and encapsulation efficiency of chimera antigen was 85%. The release profile of radiolabeled chimera indicated that only 17.4% and 20.1% of chimera were released from PLGA NPs without or with co-encapsulated CPG ODN during one month, respectively. The PLGA formulations significantly elevated titers of IgG1, IgG2a, and sIgA antibodies, as well as IL-10, and IFN-γ cytokines and also reduced the amount of TGF-β1 production relative to the other vaccines. Additionally, co-delivery of chimera and CpG ODN in PLGA NPs significantly promoted cellular and mucosal responses compared to the incorporation of CpG and chimera antigen. In summary, these results revealed that the sustained release of chimera from PLGA as an efficient polymeric system elicited potent cell-mediated and mucosal immunity without inflammatory responses against HTLV-1. Therefore, the proper design of vaccine formulation and immunization strategy are crucial factors to construct an efficient vaccine.

Pyraclostrobin-loaded poly (lactic-co-glycolic acid) nanospheres: Preparation and characteristics

We used poly (lactic-co-glycolic acid) (PLGA) as a carrier polymer for pyraclostrobin-loaded nanospheres. Using the ultrasound emulsification-solvent evaporation method, the physicochemical characteristics and release properties of the pyraclostrobin-loaded nanospheres were studied by dialysis. The optimal nanospheres prepared had a diameter of 0.6 μm, an active ingredient loading of 17.2%, and a loading rate of 89.7%. Infrared spectroscopy data and differential scanning calorimetry revealed that pyraclostrobin was successfully embedded in the carrier PLGA, and photostability tests indicated enhanced ultraviolet resistance of pyraclostrobin-loaded PLGA nanospheres nanospheres. Release property testing indicated that smaller particles had a faster release rate. Nanospheres also had a faster release rate in slightly acidic and slightly basic environments than in a neutral condition. Agitated nanospheres had a faster release rate than immobile nanospheres. The cumulative release kinetics of pyraclostrobin-loaded nanospheres was consistent with the first order kinetic equation and the Weibull equation.

Copper oxide loaded PLGA nanospheres: towards a multifunctional nanoscale platform for ultrasound-based imaging and therapy

Copper oxide nanoparticles (CuO-NPs) are increasingly becoming the subject of investigation exploring their potential use for diagnostic and therapeutic purposes. Recent work has demonstrated their anticancer potential, as well as contrast agent capabilities for magnetic resonance imaging (MRI) and through-transmission ultrasound. However, no capability of CuO-NPs has been demonstrated using conventional ultrasound systems, which, unlike the former, are widely deployed in the clinic. Furthermore, in spite of their potential as multifunctional nano-based materials for diagnosis and therapy, CuO-NPs have been delayed from further clinical application due to their inherent toxicity. Herein, we present the synthesis of a novel nanoscale system, composed of CuO-loaded PLGA nanospheres (CuO-PLGA-NS), and demonstrate its imaging detectability and augmented heating effect by therapeutic ultrasound. The CuO-PLGA-NS were prepared by a double emulsion (W/O/W) method with subsequent solvent evaporation. They were characterized as sphere-shaped, with size approximately 200 nm. Preliminary results showed that the viability of PANC-1, human pancreatic adenocarcinoma cells was not affected after 72 h exposure to CuO-PLGA-NS, implying that PLGA masks the toxic effects of CuO-NPs. A systematic ultrasound imaging evaluation of CuO-PLGA-NS, using a conventional system, was performed in vitro and ex vivo using poultry heart and liver, and also in vivo using mice, all yielding a significant contrast enhancement. In contrast to CuO-PLGA-NS, neither bare CuO-NPs nor blank PLGA-NS possess these unique advantageous ultrasonic properties. Furthermore, CuO-PLGA-NS accelerated ultrasound-induced temperature elevation by more than 4 °C within 2 min. The heating efficiency (cumulative equivalent minutes at 43 °C) was increased approximately six-fold, demonstrating the potential for improved ultrasound ablation. In conclusion, CuO-PLGA-NS constitute a versatile platform, potentially useful for combined imaging and therapeutic ultrasound-based procedures.

Functionalized Magnetic PLGA Nanospheres for Targeting and Bioimaging of Breast Cancer.

Superparamagnetic iron oxide nanoparticles (SPIONs) are actively used as highly sensitive imaging probes to provide contrast in MRI. In this study, we propose the use of SPIONs encapsulated with antibody-conjugated poly(lactic-co-glycolic acid) (PLGA) as a potent theragnostic agent. The SPIONs were synthesized by a chemical co-precipitation method of ferric and ferrous ions, and subsequently encapsulated with PLGA by using an emulsification-diffusion method. Herceptin was chemically conjugated to the SPION-encapsulating PLGA nanoparticles to target the human epidermal growth factor receptor 2 (Her2/neu) overexpressing breast cancers. FACS and MR molecular imaging revealed that the Her2/neu overexpressing cell line showed a stronger contrast enhancement than the Her2/neu non-expressing cell lines, and the signal intensity of in vivo MR imaging decreased as the concentration of Herceptin increased. This strategy of encapsulating SPIONs with PLGA will be highly useful in functionalizing magnetic nanoparticles and improving the diagnostic and therapeutic efficacy of a wide array of cancer treatments.

Menthol-loaded PLGA Micro and Nanospheres: Synthesis, Characterization and Degradation in Artificial Saliva

Menthol-loaded PLGA micro/nanospheres were synthesized using the multiple emulsion/solvent evaporation technique. Parameters such as stirring rate, external surfactant content, PLGA/menthol weight ratio, solvent evaporation and lyophilization time were evaluated as well as the degradation of micro/nanospheres in an artificial saliva medium. The menthol/PLGA micro/nanospheres thus obtained had a size distribution of between 217 nm and 13 µm and particles with spherical and dense morphology were evidenced by SEM micrographs. FTIR and TGA data showed an increase up to 60% of menthol incorporated in the micro/nanoparticles. The degradation of menthol-loaded PLGA micro/nanoparticles in artificial saliva significantly affected the particles morphology and appears to be an effective medium for releasing menthol.

Comparative study of superparamagnetic iron oxide/doxorubicin co-loaded poly (lactic-co-glycolic acid) nanospheres prepared by different emulsion solvent evaporation methods

Poly (lactic-co-glycolic acid) (PLGA) is a widely used biodegradable polymer for preparation of polymeric biodegradable carriers that shows attractive features and offers possibilities to tune the physicochemical characteristics, drug release properties and biological behaviour of the PLGA-based nanospheres. Double emulsion solvent evaporation methods fail when it comes to encapsulation of highly hydrophilic drugs such as doxorubicin (Dox). The reason for this defect is due to the rapid drug diffusion into the external aqueous phase before solidification of the PLGA nanospheres. In this study, we present a comprehensive comparison between the four different fabrication methods of PLGA nanospheres with a focus on double emulsion solvent evaporation-based methodologies to achieve the effective method for co-encapsulation of superparamagnetic iron oxide nanoparticles (SPIONs) and Dox into the PLGA polymer in terms of the size of nanoparticles, particle size distribution and drug loading. Therefore, the optimized ratio of the different phases and other process parameters of these methods is discussed. In conclusion, the prepared SPIO/Dox-PLGA nanospheres (NPs) via a modified double emulsion solvent evaporation method were found to be a promising delivery system in terms of particle size distribution, drug loading, release profile as well as magnetic properties for tumour therapeutic and diagnostic purposes.

Manufacture and characterization of chitosan/PLGA nanoparticles nanocomposite buccal films

Oral bioavailability of C-glycosyl flavonoid enriched fraction of Cecropia glaziovii (EFF-Cg) is limited due to its chemical complexity. The purpose of this study is the prospective evaluation of chitosan buccal films impregnated with EFF-Cg-loaded nanospheres as a drug delivery system for labial herpes treatment or for buccal administration. EFF-Cg-loaded PLGA nanospheres were prepared by double emulsion solvent evaporation technique. Nanoparticles were embedded into buccoadhesive chitosan films in different concentrations in order to obtain nanocomposite films. Films were characterized in term of morphology, mechanical properties and water absorption test. Furthermore a cytotoxicity assay was analyzed to evaluate the biocompatibility of systems. The results obtained from these analyses revealed that nanocomposite films present transparent appearance in all composition and Scanning Electron Microscopy (SEM) images show a continuous and compact section structure. Compared to the control film, mechanical responses of nanocomposites presented lower tensile strength values and no significant effect on the elongation at break. Dynamic Mechanical Analysis (DMA) tests indicated that increasing of NP concentration caused decreased stiffness and an increased of glass transition temperature values. Direct cytotoxicity test shows that nanoparticles and chitosan films not induce cytotoxic effect. Given the promising results, the study concludes that the developed buccal film impregnated with EFF-Cg-loaded nanospheres could be a promising approach for effective delivery of EFF-Cg.

Dermal absorption behavior of fluorescent molecules in nanoparticles on human and porcine skin models

The percutaneous passage of poorly skin absorbed molecules can be improved using nanocarriers, particularly biodegradable polymeric nanospheres (NSs) or nanocapsules (NCs). However, penetration of the encapsulated molecules may be affected by other factors than the nanocarrier properties. To gain insight information on the skin absorption of two fluorescent cargos, DiIC18(5) and coumarin-6 were incorporated in NSs or NCs and topically applied on various human and porcine skin samples. 3D imaging techniques suggest that NSs and NCs enhanced deep dermal penetration of both probes similarly, when applied on excised human skin irrespective of the nature of the cargo. However, when ex vivo pig skin was utilized, the cutaneous absorption of DiIC18(5) was more pronounced by means of PLGA NCs than NSs. In contrast, PLGA NSs noticeably improved the porcine skin penetration of coumarin-6, as compared to the NCs. Furthermore, the porcine skin results were reproducible when triplicated whereas from various human skin samples, as expected, the results were not sufficiently reproducible and large deviations were observed. The overall findings from this comprehensive comparison emphasize the potential of PLGA NCs or NSs to promote cutaneous bioavailability of encapsulated drugs, exhibiting different physicochemical properties but depending on the nature of the skin.

Preparation and characterization of uniform-sized PLGA nanospheres encapsulated with oleic acid-coated magnetic-Fe3O4 nanoparticles for simultaneous diagnostic and therapeutic applications

In recent years, magnetic nanoparticles are increasingly studied and exploited for their potential applications as magnetic resonance imaging (MRI11Magnetic resonance imaging) contrast agents, cancer treatment, targeted therapy, delivery vectors and hyperthermia. Todays, magnetic systems based on polymeric materials such as poly(lactic-co-glycolic acid) (PLGA22Poly(lactic-co-glycolic acid)) have been of special interest for their biomedical applications. In this study, we achieved an effective method for encapsulation of sized-controlled oleic acid-coated superparamagnetic iron oxide (SPIO33Superparamagnetic iron oxide NPs44Nanoparticles) into the PLGA nanospheres via a modified multiple emulsion solvent evaporation method (O1/W1/O2/W255Oil-in-water-in- oil-in-water) resulted in development of the NPs with narrow size distribution and acceptable magnetic properties that are very vital and curtail at targeting and magnetic properties of NPs for both anti-cancer therapy and magnetic resonance imaging studies. The SPIO NPs and SPIO-PLGA nanospheres showed spherical morphology with narrow size distribution of 10nm and 130nm, respectively. SPIO-PLGA nanospheres with high SPIO loading of 18.0% and magnetic properties of 5.9 emu/g were obtained. Furthermore, SPIO-PLGA NPs enhance the contrast of relaxation time (T166Relaxation time)-weighted imaging in tumor site. The prepared SPIO NPs and magnetic PLGA nanosphere could be promising superparamagnetic nanoparticles for simultaneous diagnostic and therapeutic applications.

Optimization of a simple technique for preparation of monodisperse poly(lactide-co-glycolide) nanospheres

In this study, we report the optimization of a solvent evaporation technique for preparing monodisperse poly-(lactide-co-glycolide) (PLGA) nanospheres, from a mixture of solvents composed of ethanol and PVA solution. Various experimental conditions were investigated in order to control the particle size and size distribution of the nanospheres. In addition, nanospheres containing rifampicin (RFP, an antituberculosis drug), were prepared using PLGA of various molecular weights, to study the effects of RFP as a model hydrophobic drug. The results showed that a higher micro-homogenizer stirring rate facilitated the preparation of monodisperse PLGA nanospheres with a low coefficient of variation (~20 %), with sizes below 200 nm. Increasing the PLGA concentration from 0.1 to 0.5 g resulted in an increase in the size of the obtained nanospheres from 130 to 174 nm. The molecular weight of PLGA had little effect on the particle sizes and particle size distributions of the nanospheres. However, the drug loading efficiencies of the obtained RFP/PLGA nanospheres decreased when the molecular weight of PLGA was increased. Based on these experiments, an optimized technique was established for the preparation of monodisperse PLGA nanospheres, using the method developed by the authors.

Intracellular release of rapamycin from poly (lactic acid) nanospheres modifies autophagy

The objective of this study is to investigate the autophagy activity of cells by the intracellular release of rapamycin (Rapa) of an autophagy inducer. Rapa was incorporated into nanospheres of poly (lactic-co-glycolic acid) (PLGA) for the controlled release of Rapa. Rapa was released from the PLGA nanospheres incorporating rapamycin (Rapa-PLGA-NS) with time while the Rapa-PLGA-NS were hydrolytically degraded. When human hepatocellular carcinoma (HepG2) cells were incubated with the Rapa-PLGA-NS, the Rapa-PLGA-NS were internalized, and the intracellular concentration was maintained over four days, indicating the intracellular Rapa release. The microtubule-associated protein 1 light chain (LC3) of an autophagy marker was significantly high for the Rapa-PLGA-NS group compared with the free Rapa group even after four days incubation. In addition, intracellular harmful ubiquitinated proteins were degraded by the intracellular release of Rapa even after four days incubation in contrast to free Rapa. It is concluded that the intracellular Rapa release is effective in modulating the autophagy activity over a longer time period.

PEGylated PLGA nanospheres optimized by design of experiments for ocular administration of dexibuprofen—in vitro, ex vivo and in vivo characterization

Dexibuprofen-loaded PEGylated PLGA nanospheres have been developed to improve the biopharmaceutical profile of the anti-inflammatory drug for ocular administration. Dexibuprofen is the active enantiomer of ibuprofen and therefore lower doses may be applied to achieve the same therapeutic level. According to this, two batches of nanospheres of different drug concentrations, 0.5 and 1.0mg/ml respectively, have been developed (the latter corresponding to the therapeutic ibuprofen concentration for inflammatory eye diseases). Both batches were composed of negatively charged nanospheres (­−14.1 and ­−15.9mV), with a mean particle size below 200nm, and a high encapsulation efficiency (99%). X-ray, FTIR, and DSC analyses confirmed that the drug was dispersed inside the matrix of the nanospheres. While the in vitro release profile was sustained up to 12h, the ex vivo corneal and scleral permeation profile demonstrated higher drug retention and permeation in the corneal tissue rather than in the sclera. These results were also confirmed by the quantification of dexibuprofen in ocular tissues after the in vivo administration of drug-loaded nanospheres. Cell viability studies confirmed that PEGylated-PLGA nanospheres were less cytotoxic than free dexibuprofen in the majority of the tested concentrations. Ocular in vitro (HET-CAM test) and in vivo (Draize test) tolerance assays demonstrated the non-irritant character of both nanosphere batches. In vivo anti-inflammatory effects were evaluated in albino rabbits before and after inflammation induction. Both batches confirmed to be effective to treat and prevent ocular inflammation.