Techniques for efficient entrapment of pharmaceuticals in biodegradable solid micro/nanoparticles

Manufacture and Physicochemical Properties of Chitosan Oligosaccharide/A2 β-Casein Nano-Delivery System Entrapped with Resveratrol

The purposes of this research were to form chitosan oligosaccharide (CSO)/A2 β-casein nano-delivery systems (NDSs) and to investigate the effects of production variables, such as CSO concentration levels (0.1%, 0.2%, and 0.3%, w/v) and manufacturing temperature (5°C, 20°C, and 35°C), on the production and physicochemical characteristics of CSO/A2 β-casein NDSs to carry resveratrol. The morphological characteristics of CSO/A2 β-casein NDSs were assessed by the use of transmission electron microscopy (TEM) and particle size analyzer. High-performance liquid chromatography (HPLC) was applied to determine the entrapment efficiency (EE) of resveratrol. In the TEM images, globular-shaped particles with a diameter from 126 to 266 nm were examined implying that NDSs was successfully formed. As CSO concentration level was increased, the size and zeta-potential values of NDSs were significantly (p<0.05) increased. An increase in manufacturing temperature from 5°C to 35°C resulted in a significant (p<0.05) increase in the size and polydispersity index of NDSs. Over 85% of resveratrol was favorably entrapped in CSO/A2 β-casein NDSs. The entrapment efficiency (EE) of resveratrol was significantly (p<0.05) enhanced with an increase in manufacturing temperature while CSO concentration level did not significantly affect EE of resveratrol. There were no significant (p<0.05) changes observed in the size and polydispersity index of NDSs during heat treatments and storage in model milk and yogurt indicating that CSO/A2 β-casein NDSs exhibited excellent physical stability. In conclusion, the CSO concentration level and manufacturing temperature were the crucial determinants affecting the physicochemical characteristics of CSO/A2 β-casein NDSs containing resveratrol.

Preparation and physicochemical characterization of T-OA PLGA microspheres

As the carrier of water-insoluble drugs, microspheres can play a role in increasing solubility and delaying releasing essence. The objective of this study was to improve the solubility and to delay the release of a newly discovered antitumor compound 3β-hydroxyolea-12-en-28-oic acid-3, 5, 6-trimethylpyrazin-2-methyl ester (T-OA). Early-stage preparation discovery concept (EPDC) was employed in the present study. The preparation, physicochemical characterization, and drug release properties of PLGA microspheres were evaluated. T-OA-loaded PLGA microspheres were prepared by an oil-in-water (O/W) emulsification solvent evaporation method. Characterization and release behaviors of the T-OA PLGA microspheres were evaluated by X-ray diffract (XRD), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and high performance liquid chromatography (HPLC). The results demonstrated that T-OA-loaded PLGA microspheres could be successfully obtained through solvent evaporation method with appropriate morphologic characteristics and high encapsulation efficiency. The XRD analysis showed that T-OA would be either molecularly dispersed in the polymer or distributed in an amorphous form. The DSC and FTIR analysis proved that there were interactions between T-OA and PLGA polymer. SEM observations displayed the morphology of the microspheres was homogeneous and the majority of the spheres ranged between 50 and 150 μm. The drug release behavior of the microspheres in the phosphate buffered saline medium exhibited a sustained release and the duration of the release lasted for more than 23 days, which was fit with zero-order release pattern with r² = 0.9947. In conclusion, TOA-loaded PLGA microspheres might hold great promise for using as a drug-delivery system in biomedical applications.

Inhibitory effect of a new orally active cedrol-loaded nanostructured lipid carrier on compound 48/80-induced mast cell degranulation and anaphylactic shock in mice

BACKGROUND

Type I hypersensitivity is an allergic reaction characterized by the overactivity of the immune system provoked by normally harmless substances. Glucocorticoids, anti-histamines, or mast cell stabilizers are the choices of treatment for type I hypersensitivity. Even though these drugs have the anti-allergic effect, they can have several side effects in prolong use. Cedrol is the main bioactive compound of Cedrus atlantica with anti-tumor, anti-oxidative, and platelet-activating factor inhibiting properties.

METHODS

In this study, the preparation and anti-anaphylactic effect of cedrol-loaded nanostructured lipid carriers (NLCs) were evaluated. NLCs were prepared using Compritol® 888 ATO and triolein as lipid phase and vitamin E d-α-tocopherylpolyethyleneglycol 1000 succinate, soya lecithin, and sodium deoxycholate as nanoparticle stabilizers.

RESULTS

The average diameter of cedrol-NLCs (CR-NLCs) was 71.2 nm (NLC-C1) and 91.93 nm (NLC-C2). The particle had negative zeta potential values of -31.9 mV (NLC-C1) and -44.5 mV (NLC-C2). Type I anaphylactoid reaction in the animal model is significantly reduced by cedrol and cedrol-NLC. This in vivo activity of cedrol resulted that cedrol suppressed compound 48/80-induced peritoneal mast cell degranulation and histamine release from mast cells. Furthermore, compound 48/80-evoked Ca2+ uptake into mast cells was reduced in a dose-dependent manner by cedrol and cedrol-NLC. Studies confirmed that the inhibition of type I anaphylactoid response in vivo in mice and compound 48/80-induced mast cell activation in vitro are greatly enhanced by the loading of cedrol into the NLCs. The safety of cedrol and CR-NLC was evaluated as selectivity index (SI) with prednisolone and cromolyn sodium as positive control. SI of CR-NLC-C2 was found to be 11.5-fold greater than both prednisolone and cromolyn sodium.

CONCLUSION

Administration of CR-NLC 24 hours before the onset of anaphylaxis can prevent an anaphylactoid reaction. NLCs could be a promising vehicle for the oral delivery of cedrol to protect anaphylactic reactions.

Antiepileptic Effects of Lacosamide Loaded Polymers Implanted Subdurally in GAERS

The current experiment investigated the ability of coaxial electrospun poly(D,L-lactide-co-glycolide) (PLGA) biodegradable polymer implants loaded with the antiepileptic drugs (AED) lacosamide to reduce seizures following implantation above the motor cortex in the Genetic Absence Epilepsy Rat from Strasbourg (GAERS). In this prospective, randomized, masked experiments, GAERS underwent surgery for implantation of skull electrodes (n=6), skull electrodes and blank polymers (n=6), or skull electrodes and lacosamide loaded polymers (n=6). Thirty-minute electroencephalogram (EEG) recordings were started at day 7 after surgery and continued for eight weeks. The number of SWDs and mean duration of one SWD were compared week-by-week between the three groups. There was no difference in the number of SWDs between any of the groups. However, the mean duration of one SWD was significantly lower in the lacosamide polymer group for up to 7 weeks when compared to the control group (0.004<p<0.038). The mean duration of one seizure was also lower at weeks 3, 5, 6, and 7 when compared to the blank polymer group (p= 0.016, 0.037, 0.025, and 0.025, resp.). We have demonstrated that AED loaded PLGA polymer sheets implanted on the surface of the cortex could affect seizure activity in GAERS for a sustained period.

Development of biodegradable nanoparticles for liver-specific ribavirin delivery

Ribavirin is an antiviral drug used for the treatment of chronic hepatitis C. However, ribavirin induces severe side effects such as hemolytic anemia. In this study, we prepared biodegradable nanoparticles as ribavirin carriers to modulate the pharmacokinetics of the drug. The nanoparticles encapsulating ribavirin monophosphate (RMP) were prepared from the blend of poly(d,l-lactic acid) homopolymer and arabinogalactan (AG)-poly(l-lysine) conjugate by using the solvent diffusion method in the presence of iron (III). RMP was efficiently and stably embedded in the nanoparticles and gradually released for 37 days in phosphate-buffered saline at 37°C. The coating of AG on the nanoparticles surfaces was verified by measuring the zeta potentials and performing an aggregation test of the nanoparticles using galactose-binding lectin. Moreover, the nanoparticles were efficiently internalized in cultured HepG2 cells. Ribavirin was drastically accumulated to the liver of mice after intravenous administration of the RMP-loaded nanoparticles, after which the ribavirin content gradually decreased for at least 7 days. Our results indicated successful development of nanoparticles with dual functions, targeting to the liver and sustained release of ribavirin, and suggested that the present strategy could help to advance the clinical application of ribavirin as a therapeutic agent for chronic hepatitis C.

Engineered nanoparticles for drug delivery in cancer therapy

In medicine, nanotechnology has sparked a rapidly growing interest as it promises to solve a number of issues associated with conventional therapeutic agents, including their poor water solubility (at least, for most anticancer drugs), lack of targeting capability, nonspecific distribution, systemic toxicity, and low therapeutic index. Over the past several decades, remarkable progress has been made in the development and application of engineered nanoparticles to treat cancer more effectively. For example, therapeutic agents have been integrated with nanoparticles engineered with optimal sizes, shapes, and surface properties to increase their solubility, prolong their circulation half-life, improve their biodistribution, and reduce their immunogenicity. Nanoparticles and their payloads have also been favorably delivered into tumors by taking advantage of the pathophysiological conditions, such as the enhanced permeability and retention effect, and the spatial variations in the pH value. Additionally, targeting ligands (e.g., small organic molecules, peptides, antibodies, and nucleic acids) have been added to the surface of nanoparticles to specifically target cancerous cells through selective binding to the receptors overexpressed on their surface. Furthermore, it has been demonstrated that multiple types of therapeutic drugs and/or diagnostic agents (e.g., contrast agents) could be delivered through the same carrier to enable combination therapy with a potential to overcome multidrug resistance, and real-time readout on the treatment efficacy. It is anticipated that precisely engineered nanoparticles will emerge as the next-generation platform for cancer therapy and many other biomedical applications.

A novel approach to monitor intracellular degradation kinetics of poly(lactide-co-glycolide) nanoparticles by means of flow cytometry

The intracellular degradation of poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) is studied by means of flow cytometry (FACS). NPs are prepared with PLGA of two different ratios of the d,l-lactide and glycolide blocks: 85 : 15 and 65 : 35. PLGA molecules are labelled with rhodamine B. Flow cytometry is first used to follow the degradation of PLGA NPs in PBS over time by measuring the decrease in fluorescence per particle. The 85 : 15 PLGA NPs progressively degrade during the first 10 days and remain constant thereafter. The 65 : 35 PLGA NPs remain unaltered, showing no changes in fluorescence intensity. FACS data are confirmed by transmission electron microscopy and dynamic light scattering measurements. Intracellular degradation of 85 : 15 PLGA is measured by the increase in fluorescence intensity in the cell population with time due to the liberation of rhodamine B labelled PLGA molecules from NPs in the cell interior where rhodamine displays an increased quantum yield. The fluorescence intensity from 85 : 15 PLGA NPs increases up to 24 hours, remaining constant thereafter. No change in the fluorescence of 65 : 35 PLGA NPs is observed after 4 days. The intracellular behaviour of the PLGA NPs is also confirmed by confocal Raman microscopy.

Study of intracellular delivery of doxorubicin from poly(lactide-co-glycolide) nanoparticles by means of fluorescence lifetime imaging and confocal Raman microscopy

The intracellular delivery of Doxorubicin (Dox) from poly(lactide-co-glycolide) (PLGA) nanoparticles stabilised with bovine serum albumin, in HepG2 cells, is studied via flow cytometry, fluorescence lifetime imaging microscopy (FLIM), confocal Raman microscopy (CRM) and cell viability studies. Flow cytometry shows that the initial uptake of PLGA and Dox follow the same kinetics. However, following 8 h of incubation, the fluorescence intensity and cellular uptake of Dox decreases, while in the case of PLGA both parameters remain constant. FLIM shows the presence of a single-lifetime species, with a lifetime of 1.15 ns when measured inside the cells. Cell viability decreases by approximately 20% when incubated for 24 h with PLGA loaded with Dox, with a particle concentration of 100 µg · mL(-1). At the single-cell level, CRM shows changes in the bands from DNA and proteins in the cell nucleus when incubated with PLGA loaded with Dox.

Poly(methyl methacrylate) particulate carriers in drug delivery

Poly(methyl methacrylate) (PMMA) is one of the most widely explored biomedical materials because of its biocompatibility, and recent publications have shown an increasing interest in its applications as a drug carrier. PMMA-based particulate carriers (PMMA(P)) can be prepared either by polymerization methods or from pre-formed polymer-based techniques. Potential biomedical application of these particles includes their use as adjuvant for vaccines and carrier of many drugs as antibiotics and antioxidants via different routes of administration. Release of drugs from PMMA(P) occurs typically in a biphasic way with an incomplete drug release. To improve release profiles, recent strategies are focusing on increasing polymer hydrophilicity by synthesizing functionalized PMMA microspheres or by formulating PMMA composites with hydrophilic polymers. This review examines the current status of preparation techniques, drug release kinetics, biomedical applications and toxicity of these nano/micro PMMA-based particulate carriers.

Improved drug loading and antibacterial activity of minocycline-loaded PLGA nanoparticles prepared by solid/oil/water ion pairing method

Background

Low drug entrapment efficiency of hydrophilic drugs into poly(lactic-co-glycolic acid) (PLGA) nanoparticles is a major drawback. The objective of this work was to investigate different methods of producing PLGA nanoparticles containing minocycline, a drug suitable for periodontal infections.

Methods

Different methods, such as single and double solvent evaporation emulsion, ion pairing, and nanoprecipitation were used to prepare both PLGA and PEGylated PLGA nanoparticles. The resulting nanoparticles were analyzed for their morphology, particle size and size distribution, drug loading and entrapment efficiency, thermal properties, and antibacterial activity.

Results

The nanoparticles prepared in this study were spherical, with an average particle size of 85–424 nm. The entrapment efficiency of the nanoparticles prepared using different methods was as follows: solid/oil/water ion pairing (29.9%) > oil/oil (5.5%) > water/oil/water (4.7%) > modified oil/water (4.1%) > nano precipitation (0.8%). Addition of dextran sulfate as an ion pairing agent, acting as an ionic spacer between PEGylated PLGA and minocycline, decreased the water solubility of minocycline, hence increasing the drug entrapment efficiency. Entrapment efficiency was also increased when low molecular weight PLGA and high molecular weight dextran sulfate was used. Drug release studies performed in phosphate buffer at pH 7.4 indicated slow release of minocycline from 3 days to several weeks. On antibacterial analysis, the minimum inhibitory concentration and minimum bactericidal concentration of nanoparticles was at least two times lower than that of the free drug.

Conclusion

Novel minocycline-PEGylated PLGA nanoparticles prepared by the ion pairing method had the best drug loading and entrapment efficiency compared with other prepared nanoparticles. They also showed higher in vitro antibacterial activity than the free drug.

Novel Strategy to Fabricate PLA/Au Nanocomposites as an Efficient Drug Carrier for Human Leukemia Cells in Vitro

Poly (lactic acid) (PLA) polymer has the promising applications in the biomedical field because of its biodegradability and safe elimination. In this study, we have explored the bio-application of new nanocomposites composed with PLA nanofibers and Au nanoparticles as the potential drug carrier for an efficient drug delivery in target cancer cells. The results demonstrated that the anticancer drug daunorubicin could be efficiently self-assembled on the surface of PLA/Au nanocomposites and the synergistic enhancement of PLA/Au nanocomposites conjugated with daunorubicin into drug-sensitive K562 and drug-resistant leukemia K562/AO2 cells could be obviously observed by MTT assay and confocal fluorescence microscopy studies. These observations suggest that the new nanocomposites could readily induce daunorubicin to accumulate and uptake in target leukemia cells and increase the drug's cytotoxicity. Especially, the PLA/Au nanocomposites could significantly facilitate the cellular drug absorbtion of daunorubicin into drug-resistant K562/AO2 cells and efficiently inhibit the cancer cell proliferation. This raised the possibility to utilize the PLA/Au nanocomposites as a new effective additive agent to inhibit the drug resistance and thus as a novel strategy to sensitively track the respective cancer cells.

Surface engineered Poly(lactide-co-glycolide) nanoparticles for intracellular delivery: uptake and cytotoxicity--a confocal raman microscopic study

Confocal Raman Microscopy (CRM) is used to study the cell internalization of poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) fabricated by emulsion techniques with either poly(ethylene imine) (PEI) or bovine serum albumin (BSA) as surface stabilizers. HepG2 cells were exposed to PEI and BSA stabilized PLGA NPs. Spontaneous Confocal Raman Spectra taken in one and the same spot of exposed cells showed bands arising from the cellular environment as well as bands characteristic for PLGA, proving that the PLGA NPs have been internalized. It was found that PLGA NPs preferentially colocalize with lipid bodies. The results from Raman spectroscopy are compared with flow cytometry and confocal scanning laser microscopy (CLSM) data. The advantages of CRM as a label-free technique over flow cytometry and CLSM are discussed. Additionally, cell viability studies by means of quick cell counting solution and MTT tests in several cell lines show a generally low toxicity for both PEI and BSA stabilized PLGA NPs, with BSA stabilized PLGA NPs having an even lower toxicity than PEI stabilized.