Piping Lv

Surface Charge Affects Cellular Uptake and Intracellular Trafficking of Chitosan-Based Nanoparticles

Chitosan-based nanoparticles (NPs) are widely used in drug delivery, device-based therapy, tissue engineering, and medical imaging. In this aspect, a clear understanding of how physicochemical properties of these NPs affect the cytological response is in high demand. The objective of this study is to evaluate the effect of surface charge on cellular uptake profiles (rate and amount) and intracellular trafficking. We fabricate three kinds of NPs (∼ 215 nm) with different surface charge via SPG membrane emulsification technique and deposition method. They possess uniform size as well as identical other physicochemical properties, minimizing any differences between the NPs except for surface charge. Moreover, we extend our research to eight cell lines, which could help to obtain a representative conclusion. Results show that the cellular uptake rate and amount are both positively correlated with the surface charge in all cell line. Subsequent intracellular trafficking indicates that some of positively charged NPs could escape from lysosome after being internalized and exhibit perinuclear localization, whereas the negatively and neutrally charged NPs prefer to colocalize with lysosome. These results are critical in building the knowledge base required to design chitosan-based NPs to be used efficiently and specifically.

Preparation and evaluation of alginate-chitosan microspheres for oral delivery of insulin

The alginate-chitosan microspheres with narrow size distribution were prepared by membrane emulsification technique in combination with ion (Ca(2+)) and polymer (chitosan) solidification. The preparation procedure was observed, and the physical properties (particle size distribution, surface morphology, chitosan distribution, zeta potential) of the microspheres were characterized. Subsequently, the microspheres were employed to load model peptide of insulin. The effect of loading ways on the loading efficiency and immunological activity of insulin were investigated. It was shown that the higher loading efficiency (56.7%) and remarkable activity maintenance (99.4%) were obtained when the insulin was loaded during the chitosan solidification process (Method B). Afterward, the release profile in vitro for the optimal insulin-loaded microspheres was investigated. Under the pH conditions of gastrointestinal environment, only 32% of insulin released during the simulated transit time of drug (2 h in the stomach and 4 h in the intestinal). While under the pH condition of blood environment, insulin release was stable and sustained for a long time (14 days). Furthermore, the chemical stability of insulin released from the microspheres was well preserved after they were treated with the simulated gastric fluid containing pepsin for 2 h. Finally, the blood glucose level of diabetic rats could be effectively reduced and stably kept for a long time (∼60 h) after oral administration of the insulin-loaded alginate-chitosan microspheres. Therefore, the alginate-chitosan microspheres were found to be promising vectors showing a good efficiency in oral administration of protein or peptide drugs.

Particle size affects the cellular response in macrophages

A deeper understanding of how the physical properties of particles regulate specific biological responses is becoming a crucial requirement for their successful biomedical application. To provide insights on their design and application, J774A.1 cells are exposed to particles with different diameters (430 nm, 1.9 μm and 4.8 μm), and the size effects on a series of cellular responses in macrophages are evaluated. Cellular uptake study demonstrates that nanosized particles accumulate in the cells at a faster rate, and with a higher surface area. Once the data are converted into the expression of particle volume, the maximum value is found with 1.9 μm particles instead of nanoparticles. Moreover, the uptake intermediates are also trapped, and the steps of particle internalization include filopodia sensing, skeleton rearrangement, and morphology change. Subsequent cellular trafficking reveals that only nanosized particles transport via lysosomal pathway, which is consistent with their uptake mechanisms. Furthermore, nanosized particles prefer to promote the secretion of Th1-specific molecule signals (e.g. IFN, IL-12) rather than immune suppressors. All these results, along with a couple of surprises, are discussed in the view of clinical practice. They are expected, in principle, to establish the basis of new design concepts for particle-based biomedical applications.

POROUS QUATERNIZED CHITOSAN NANOPARTICLES CONTAINING PACLITAXEL NANOCRYSTALS IMPROVED THERAPEUTIC EFFICACY IN NON-SMALL-CELL LUNG CANCER AFTER ORAL ADMINISTRATION

Clinical application of paclitaxel (PTX) is limited because of its poor solubility in aqueous media. To overcome this hurdle, we devised an oral delivery system by encapsulating PTX into N-((2-hydroxy-3-trimethylammonium) propyl) chitosan chloride (HTCC) nanoparticles. These nanoparticles were small (~130 nm), had a narrow size distribution, and displayed high loading efficiency owing to the homogeneous distribution of PTX nanocrystals. The matrix hydrophilicity and porous structure of the obtained nanoparticles accelerated their degradation and improved drug release. In vitro and in vivo transport experiments had proved that the presence of positive charges enhanced the intestinal permeability of these nanoparticles. Further in vitro experiment of cytotoxicity showed that the PTX-loaded HTCC nanoparticle (HTCC-NP:PTX) was more effective than native PTX owing to enhanced cellular uptake. Drug distribution in tissues and in vivo imaging studies confirmed the preferred accumulation of HTCC-NP:PTX in subcutaneous tumor tissue. Subsequent tumor xenograft assays demonstrated the promising therapeutic effect of HTCC-NP:PTX on inhibition of tumor growth and induction of apoptosis in tumor cells. Additional investigation into side effects revealed that HTCC-NP:PTX caused lower Cremophor EL-associated toxicities compared with Taxol. These results strongly supported the notion that HTCC nanoparticle (HTCC-NP) is a promising candidate as an oral carrier of PTX for cancer therapy.

Targeted Delivery of Insoluble Cargo (Paclitaxel) by PEGylated Chitosan Nanoparticles Grafted with Arg-Gly-Asp (RGD)

Poor delivery of insoluble anticancer drugs has so far precluded their clinical application. In this study, we developed a tumor-targeting delivery system for insoluble drug (paclitaxel, PTX) by PEGylated O-carboxymethyl-chitosan (CMC) nanoparticles grafted with cyclic Arg-Gly-Asp (RGD) peptide. To improve the loading efficiency (LE), we combined O/W/O double emulsion method with temperature-programmed solidification technique and controlled PTX within the matrix network as in situ nanocrystallite form. Furthermore, these CMC nanoparticles were PEGylated, which could reduce recognition by the reticuloendothelial system (RES) and prolong the circulation time in blood. In addition, further graft of cyclic RGD peptide at the terminal of PEG chain endowed these nanoparticles with higher affinity to in vitro Lewis lung carcinoma (LLC) cells and in vivo tumor tissue. These outstanding properties enabled as-designed nanodevice to exhibit a greater tumor growth inhibition effect and much lower side effects over the commercial formulation Taxol.

Uniform-sized silicone oil microemulsions: Preparation, investigation of stability and deposition on hair surface

Emulsions are commonly used in foods, pharmaceuticals and home-personal-care products. For emulsion based products, it is highly desirable to control the droplet size distribution to improve storage stability, appearance and in-use property. We report preparation of uniform-sized silicone oil microemulsions with different droplets diameters (1.4-40.0 μm) using SPG membrane emulsification technique. These microemulsions were then added into model shampoos and conditioners to investigate the effects of size, uniformity, and storage stability on silicone oil deposition on hair surface. We observed much improved storage stability of uniform-sized microemulsions when the droplets diameter was ≤22.7 μm. The uniform-sized microemulsion of 40.0 μm was less stable but still more stable than non-uniform sized microemulsions prepared by conventional homogenizer. The results clearly indicated that uniform-sized droplets enhanced the deposition of silicone oil on hair and deposition increased with decreasing droplet size. Hair switches washed with small uniform-sized droplets had lower values of coefficient of friction compared with those washed with larger uniform and non-uniform droplets. Moreover the addition of alginate thickener in the shampoos and conditioners further enhanced the deposition of silicone oil on hair. The good correlation between silicone oil droplets stability, deposition on hair and resultant friction of hair support that droplet size and uniformity are important factors for controlling the stability and deposition property of emulsion based products such as shampoo and conditioner.

Molecular structure matters: PEG-b-PLA nanoparticles with hydrophilicity and deformability demonstrate their advantages for high-performance delivery of anti-cancer drugs

Various carriers are being advanced for anti-cancer therapy, which can protect drugs and ferry them to the target site. However, little understanding exists regarding the effect of molecular structure on anti-cancer drug delivery efficiency. To fill this knowledge gap, we take poly(lactic acid) (PLA), poly(lactide-co-glycolide) (PLGA), and poly-ethylene glycol-co-poly-lactide (PEG-b-PLA) polymers as prototype materials and comparatively explore the inherent relationship between the molecular structure and the delivery ability. Compared with PLA and PLGA NPs, PEG-b-PLA ones possess the advantages of longer blood circulation time, more tumor accumulation, and better intratumoral delivery ability. Subsequent mechanism investigations reveal that the molecular structure will regulate the polymer arrangement and render NPs different hydrophilicity/deformability, which dictate the distinct delivery performances. Finally, the superior PEG-b-PLA NPs are further loaded with the anti-cancer drug paclitaxel (PTX) and functionalized with magnetic (M) Fe3O4 nanocrystals. As-designed PTX/M PEG-b-PLA NPs show much better tumor inhibition efficacy and fewer side effects than the commercialized Taxol® formulation, strongly supporting their use as high-performance carriers for anti-cancer therapy.

Potential pharmaceutical applications of uniform-sized chitosan micro/nanoparticles with autofluorescent property

Chinese Acad Sci, Inst Proc Engn, State Key Lab Biochem Engn, Beijing 100190, Peoples R China