SN-38 loading capacity of hydrophobic polymer blend nanoparticles: formulation, optimization and efficacy evaluation.

One of the most important problems in nanoencapsulation of extremely hydrophobic drugs is poor drug loading due to rapid drug crystallization outside the polymer core. The effort to use nanoprecipitation, as a simple one-step procedure with good reproducibility and FDA approved polymers like Poly(lactic-co-glycolic acid) (PLGA) and Polycaprolactone (PCL), will only potentiate this issue. Considering that drug loading is one of the key defining characteristics, in this study we attempted to examine whether the nanoparticle (NP) core composed of two hydrophobic polymers will provide increased drug loading for 7-Ethyl-10-hydroxy-camptothecin (SN-38), relative to NPs prepared using individual polymers. D-optimal design was applied to optimize PLGA/PCL ratio in the polymer blend and the mode of addition of the amphiphilic copolymer Lutrol®F127 in order to maximize SN-38 loading and obtain NPs with acceptable size for passive tumor targeting. Drug/polymer and polymer/polymer interaction analysis pointed to high degree of compatibility and miscibility among both hydrophobic polymers, providing core configuration with higher drug loading capacity. Toxicity studies outlined the biocompatibility of the blank NPs. Increased in vitro efficacy of drug-loaded NPs compared to the free drug was confirmed by growth inhibition studies using SW-480 cell line. Additionally, the optimized NP formulation showed very promising blood circulation profile with elimination half-time of 7.4 h.

Lactobacillus casei Encapsulated in Soy Protein Isolate and Alginate Microparticles Prepared by Spray Drying.

This article presents a novel formulation for preparation of Lactobacillus casei 01 encapsulated in soy protein isolate and alginate microparticles using spray drying method. A response surface methodology was used to optimise the formulation and the central composite face-centered design was applied to study the effects of critical material attributes and process parameters on viability of the probiotic after microencapsulation and in simulated gastrointestinal conditions. Spherical microparticles were produced in high yield (64%), narrow size distribution (d50=9.7 µm, span=0.47) and favourable mucoadhesive properties, with viability of the probiotic of 11.67, 10.05, 9.47 and 9.20 log CFU/g after microencapsulation, 3 h in simulated gastric and intestinal conditions and four-month cold storage, respectively. Fourier-transform infrared spectroscopy confirmed the probiotic stability after microencapsulation, while differential scanning calorimetry and thermogravimetry pointed to high thermal stability of the soy protein isolate-alginate microparticles with encapsulated probiotic. These favourable properties of the probiotic microparticles make them suitable for incorporation into functional food or pharmaceutical products.

Comparative biodistribution studies of technetium-99 m radiolabeled amphiphilic nanoparticles using three different reducing agents during the labeling procedure.

Considering the confusing biodistribution data through the literature and few reported alerts as well as our preliminary biodistribution results, we decided to evaluate the interaction and interference of the commonly present (99m) Tc (technetium-99m)-stannic oxide colloid during the direct stannous chloride (99m) Tc-labeling procedure and to assess its influence on the biodistribution pattern of amphiphilic poly(lactic-co-glycolic acid) nanoparticles. In order to confirm our thesis, beside stannous chloride, we employed two different reducing agents that don't form colloidal particles. The use of sodium borohydride was previously reported in the literature, whereas sodium dithionite was adapted for the first time in the (99m) Tc direct labeling procedure for nanoparticles. The results in our paper clearly differentiate among samples with and without colloidal impurities originating from the labeling procedure with a logical follow up of the radiochemical, physicochemical evaluation, and biodistribution studies clarifying previously reported data on stannic oxide colloidal interference. (99m) Tc-nanoparticle complex labeled with sodium dithionite as reducing agent illustrated appropriate labeling efficacy, stability, and potential for further use in biodistribution studies thus providing solution for the problem of low-complex stability when sodium borohydride is used and colloidal stannic oxide interference for stannous chloride procedure.

Wheat germ agglutinin-functionalised crosslinked polyelectrolyte microparticles for local colon delivery of 5-FU: in vitro efficacy and in vivo gastrointestinal distribution.

We have previously reported the development and characterisation of wheat germ agglutinin (WGA)-functionalised chitosan-Ca-alginate (CTS-Ca-ALG) microparticles (MPs) loaded with acid-resistant particles of 5-fluorouracil (5-FU). In the present work, our goal was to evaluate the potential of these carriers for efficient treatment of colon cancer by studying in vitro permeability and cell association of 5-FU and [methyl-³H]thymidine uptake in Caco-2 cells, as well as in vivo gastrointestinal distribution. The amount of 5-FU permeated through Caco-2 cells was 15.1, 7.7 and 6.5% for 5-FU solution, CTS-Ca-ALG MPs and WGA conjugates. The concentration of 5-FU associated with Caco-2 cells was significantly greater when delivered from MPs. By incorporation of 5-FU into MPs and further decoration with WGA, an increased [methyl-³H]thymidine uptake was observed few hours after continuous drug treatment followed by significantly reduced uptake after 6 h. Gastrointestinal distribution was in favour of increased localisation and concentration of the particles in colon region.

Efficacy assessment of self-assembled PLGA-PEG-PLGA nanoparticles: Correlation of nano-bio interface interactions, biodistribution, internalization and gene expression studies.

The aim of our study was to develop and compare the biological performance of two types of biodegradable SN-38 loaded nanoparticles (NPs) with various surface properties, composed of low and high Mw triblock PLGA-PEG-PLGA copolymers, applying rational quality and safety by design approach. Therefore, along with the optimization of crucial physico-chemical properties and in order to evaluate the therapeutical potential and biocompatibility of prepared polymeric nanoparticles, analysis of nano-bio interactions, cell internalization, gene expression and biodistribution studies were performed. The optimized formulations, one of low Mw and one composed of high Mw PLGA-PEG-PLGA copolymer, exhibited different characteristics in terms of surface properties, particle size, zeta potential, drug loading, protein adsorption and biodistribution, which may be attributed to the variations in nano-bio interface interactions due to different NP building blocks length and Mw. On the contrary to protein adsorption and biodistribution studies, both types of NPs exhibited similar results during cell internalization and gene expression studies performed in cell culture medium containing serum proteins. This pool of useful data for internalization and efficacy as well as the notable advance in the circulation time of low Mw NPs may be further employed for shaping the potential of the designed nanocarriers.

PEO-PPO-PEO/Poly(DL-lactide-co-caprolactone) Nanoparticles as Carriers for SN-38: Design, Optimization and Nano-Bio Interface Interactions.

Encapsulation of extremely hydrophobic substances such as SN-38 into nanoparticles, is a promising approach to solve the solubility issue and enable drug administration. Moreover, nanocarriers' tumor homing behavior, targeted and controlled release at the site of action will optimize therapeutic potency and decrease toxicity of the incorporated drug substance. However, the enormous drug hydrophobicity might limit the capacity for encapsulation as the premature drug precipitation will contribute to fast free drug crystal growth, low drug incorporation and huge waste of the active material. In this article we defined the optimal region for manufacturing of SN-38 loaded PEO-PPO-PEO/P(DL)LCL nanoparticles (NPs) with high efficacy of encapsulation, suitable particle size and different surface properties, using D-optimal design and nanoprecipitation as production method. Further we made an approach to investigate the interactions with macromolecules at the nano-bio interface which are predetermined by the physico-chemical and surface properties of the NPs, and are important determinants for the biological identity of the nanoparticles, the potential for evasion of the physiological barriers and the efficacy of localization at the site of action. Here we present in depth analysis of the behavior of two types of nanoparticles with different surface properties through structured protein interaction and bioreactivity experiments in order to presuppose NP performance and toxicological profile in biological environment.

Synthesis and self-assembly of amphiphilic poly(acrylicacid)-poly(ɛ-caprolactone)-poly(acrylicacid) block copolymer as novel carrier for 7-ethyl-10-hydroxy camptothecin.

The process of molecular self-assembly plays a crucial role in formulation of polymeric nanoparticulated drug delivery carriers as it creates the possibility for enhanced drug encapsulation and carrier surface engineering. This study aimed to develop a novel self-assembled polymeric micelles for targeted delivery in tumor cells in order to overcome not only various drawbacks of 7-ethyl-10-hydroxy camptothecin (SN-38) but also various reported limitations of other drug delivery systems, especially low drug loading and premature release. Custom synthesized amphiphilic triblock copolymer poly(acrylic acid)-poly(ɛ-caprolactone)-poly(acrylic acid) (PAA(13)-PCL(35)-PAA(13)) was used to prepare kinetically stable micelles by nanoprecipitation and modified nanoprecipitation procedure. Core-shell micelles with diameter of 120-140 nm, negative zeta potential and satisfactory drug loading were produced. The prepared formulations were stable in pH range of 3-12 and in media with NaCl concentration <1 mol/l. Screening mixed level factorial 3 × 2(2) design identified that the process temperature as well as the type of organic solvent has influence upon the efficacy of encapsulation, particle size, dissolution rate and burst release. Fourier transform infrared and differential scanning calorimetry analyses confirmed the entrapment of the active substance into the micelles. The kinetic analysis of dissolution studies revealed that the main mechanism of drug release from the prepared formulations is Fickian diffusion. Growth inhibition studies as well as DNA fragmentation assay performed on SW-480 cell lines clearly demonstrated increased growth inhibition effect and presence of fragmented DNA in cells treated with loaded micelles compared to SN-38 solution. Altogether, these results point out to potential biomedical and clinical application of PAA-PCL-PAA systems in the future.