Preparation of cationic biodegradable dextran microspheres loaded with BSA and study on the mechanism of protein loading

The effect of spacers in dual drug-polymer conjugates toward combination therapeutic efficacy

Recently, a great effort has been made to perfect the therapeutic effect of solid tumor, from single-agent therapy to combined therapy and many other polymer-drug conjugations with dual or more anticancer agents due to their promising synergistic effect and higher drug level accumulation towards tumor tissues. Different polymer-drug spacers present diverse therapeutic efficacy, therefore, finding an appropriate spacer is desirable. In this study, dual drugs that are doxorubicin (DOX) and mitomycin C (MMC) were conjugated onto a polymer carrier (xyloglucan) via various peptide or amide bonds, and a series of polymers drug conjugates were synthesized with different spacers and their effect on tumor treatment efficacy was studied both in vitro and in vivo. The result shows that the synergistic effect is better when using different linker to conjugate different drugs rather than using the same spacer to conjugate different drugs on the carrier. Particularly, the finding of this works suggested that, using peptide bond for MMC and amide bond for DOX to conjugate dual drugs onto single XG carrier could improve therapeutic effect and synergy effect. Therefore, in polymer-pharmaceutical formulations, the use of different spacers to optimize the design of existing drugs to enhance therapeutic effects is a promising strategy.

Nanocarrier-Based Combination Chemotherapy for Resistant Tumor: Development, Characterization, and Ex Vivo Cytotoxicity Assessment

A folic acid-conjugated paclitaxel (PTX)-doxorubicin (DOX)-loaded nanostructured lipid carrier(s) (FA-PTX-DOX NLCs) were prepared by using emulsion-evaporation method and extensively characterized for particle size, polydispersity index, zeta potential, and % entrapment efficiency which were found to be 196 ± 2.5 nm, 0.214 ± 0.04, +23.4 ± 0.3 mV and 88.3 ± 0.2% (PTX), and 89.6 ± 0.5% (DOX) respectively. In vitro drug release study of optimized formulation was carried out using dialysis tube method. FA-conjugated PTX-DOX-loaded NLCs showed 75.6 and 78.4% (cumulative drug release) of PTX and DOX respectively in 72 h in PBS (pH 7.4)/methanol (7:3), while in the case of FA-conjugated PTX-DOX-loaded NLCs, cumulative drug release recorded was 80.4 and 82.8% of PTX and DOX respectively in 72 h in PBS (pH 4.0)/methanol (7:3). Further, the formulation(s) were evaluated for ex vivo cytotoxicity study. The cytotoxicity assay in doxorubicin-resistant human breast cancer MCF-7/ADR cell lines revealed lowest GI₅₀ value of FA-D-P NLCs which was 1.04 ± 0.012 μg/ml, followed by D-P NLCs and D-P solution with GI₅₀ values of 3.12 ± 0.023 and 3.89 ± 0.007 μg/ml, respectively. Findings indicated that the folic acid-conjugated PTX and DOX co-loaded NLCs exhibited lower GI₅₀ values as compared to unconjugated PTX and DOX co-loaded NLCs; thus, they have relatively potential anticancer efficacy against resistant tumor.

Alkaline poly(ethylene glycol)-based hydrogels for a potential use as bioactive wound dressings

The number of patients with chronic wounds is increasing constantly in today's aging society. However, little work is done so far tackling the associated disadvantageous shift of the wound pH. In our study, we developed two different approaches on pH-modulating wound dressing materials, namely, bioactive interpenetrating polymer network hydrogels based on poly(ethylene glycol) diacrylate/N-vinylimidazole/alginate (named VI_x ) and poly(ethylene glycol) diacrylate/2-dimethylaminoethyl methacrylate/N-carboxyethylchitosan (named DMAEMA_x ). Both formulations showed a good cytocompatibility and wound healing capacity in vitro. The developed dressing materials significantly increased the cell ingrowth in wounded human skin constructs; by 364% and 313% for the VI_x and the DMAEMA_x hydrogel formulation, respectively. Additionally, VI_x hydrogels were found to be suitable scaffolds for superficial cell attachment. Our research on the material properties suggests that ionic interactions and hydrogen bonds are the driving forces for the mechanical and swelling properties of the examined hydrogels. High amounts of positively charged amino groups in DMAEMA_x hydrogels caused increased liquid uptake (around 190%), whereas VI_x hydrogels showed a 10-fold higher maximum compressive stress in comparison to hydrogels without ionizable functional groups. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3360-3368, 2017.

Coated biodegradable casein nanospheres: a valuable tool for oral drug delivery

Biodegradable casein nanospheres for the sustained release of bioactive molecules in the gastro-intestinal tract were prepared by precipitation polymerization using sodium methacrylate (NaMA) and N,N'-methylene bis-acrylamide (MEBA) as pH-responsive monomer and cross-linker. Three materials with different casein amount were obtained and characterized by scanning electron microscopy, dimensional analysis, water uptake, cytotoxicity and enzymatic degradation experiments. Nanospheres biodegradability was tuned by coating with polyacrylic acid. Coated and uncoated materials were investigated as delivery vehicles for diclofenac sodium salt. For un-coated samples, the release raise 100% in 30 h, while for coated specimens these values were lower than 70%, due to the diffusional constraints of polymer layer.

Temporal-controlled Dexamethasone Releasing Chitosan Nanoparticle System Enhances Odontogenic Differentiation of Stem Cells from Apical Papilla

INTRODUCTION

The spatial and temporal control of stem cell differentiation into odontoblast-like cells remains one of the major challenges in regenerative endodontic procedures. The current study aims to synthesize and compare the effect of dexamethasone (Dex) release from 2 variants of Dex-loaded chitosan nanoparticles (CSnp) on the odontogenic differentiation of stem cells from apical papilla (SCAP).

METHODS

Two variants of Dex-loaded CSnp were synthesized by encapsulation (Dex-CSnpI) and adsorption (Dex-CSnpII) methods. The physicochemical characterization of Dex-CSnpI and Dex-CSnpII was assessed by transmission electron microscopy, Zetasizer, and Fourier transform infrared spectroscopy, whereas the Dex release kinetics was assessed by spectrophotometry. A previously characterized SCAP cell line was cultured onto CSnp, Dex-CSnpI, or Dex-CSnpII. The biomineralization potential was determined by alizarin red staining. Alkaline phosphatase, dentin sialophosphoprotein, and dentin matrix protein-1 gene expressions were analyzed by real-time reverse-transcription polymerase chain reaction.

RESULTS

Dex-CSnpI resulted in slower release of Dex compared with Dex-CSnpII, but both demonstrated sustained release of Dex for 4 weeks. Biomineralization of SCAP was significantly higher (P < .05) in presence of Dex-CSnpII compared with that in Dex-CSnpI at 3 weeks. Alkaline phosphatase gene expression was significantly higher in the presence of Dex-CSnpII compared with Dex-CSnpI, with peak expression seen at 2 weeks (P < .05). The expression of odontogenic specific marker dentin matrix protein-1 was significantly higher in presence of Dex-CSnpII compared with Dex-CSnpI at 3 weeks (P < .05).

CONCLUSIONS

Collectively, these data suggest that sustained release of Dex results in enhanced odontogenic differentiation of SCAP. These findings highlight the potential of temporal-controlled delivery of bioactive molecules to direct the spatial- and temporal-controlled odontogenic differentiation of dental stem cells.

Self-organized nanoparticle drug delivery systems from a folate-targeted dextran–doxorubicin conjugate loaded with doxorubicin against multidrug resistance

DOX nano-DDSs with the function of both targeting tumors and controlling drug release were prepared which exhibited larger drug releases, higher cytotoxicity against HepG2/DOX cells, improved cellular uptake and decreased side toxicities.

Encapsulation of albumin in self-assembled layer-by-layer microcapsules: comparison of co-precipitation and adsorption techniques

OBJECTIVE

The objective of this study is to prepare and characterize polymeric self-assembled layer-by-layer microcapsules (LbL-MC) to deliver a model protein, bovine serum albumin (BSA). The aim is to compare the BSA encapsulation in LbL-MC using co-precipitation and adsorption methods.

MATERIALS AND METHODS

In co-precipitation method, BSA was co-precipitated with growing calcium carbonate particles to form a core template. Later, poly(styrene sulfonate) and poly(allylamine hydrochloride) were sequentially adsorbed onto the CaCO3 templates. In adsorption method, preformed LbL-MC were incubated with BSA and encapsulation efficiency is optimized for pH and salt concentration. Free and BSA-encapsulated LbL-MC were characterized using Zetasizer, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and differential scanning calorimeter. Later, in vitro release studies were performed using dialysis membrane method at pH 4, 7.4 and 9.

RESULTS AND DISCUSSION

Results from Zetasizer and SEM showed free LbL-MC with an average size and zeta-potential of 2.0 ± 0.6 μm and 8.1 ± 1.9 mV, respectively. Zeta-potential of BSA-loaded LbL-MC was (-)7.4 ± 0.7 mV and (-)5.7 ± 1.0 mV for co-precipitation and adsorption methods, respectively. In adsorption method, BSA encapsulation in LbL-MC was found to be greater at pH 6.0 and 0.2 M NaCl. Co-precipitation method provided four-fold greater encapsulation efficiency (%) of BSA in LbL-MC compared with adsorption method. At pH 4, the BSA release from LbL-MC was extended up to 120 h. Polyacrylamide gel electrophoresis showed that BSA encapsulated in LBL-MC through co-precipitation is stable toward trypsin treatment.

CONCLUSION

In conclusion, co-precipitation method provided greater encapsulation of BSA in LbL-MC. Furthermore, LbL-MC can be developed as carriers for pH-controlled protein delivery.

Temporal-controlled release of bovine serum albumin from chitosan nanoparticles: effect on the regulation of alkaline phosphatase activity in stem cells from apical papilla

INTRODUCTION

The controlled delivery of bioactive molecules is crucial for the regulation of stem cell differentiation. In this study, we examined the effects of temporal-controlled release of bovine serum albumin (BSA) from chitosan nanoparticles (CSnp) to regulate the alkaline phosphatase activity (ALP) in stem cells from apical papilla (SCAP).

METHODS

BSA-loaded CSnp were synthesized by 2 methods to achieve the variant temporal-controlled release: (1) the encapsulation technique (BSA-CSnpI) and (2) the adsorption technique (BSA-CSnpII). After characterization of the size, charge, and release kinetics, SCAP were cultured in the presence of these bioactive molecule-loaded nanoparticles. SCAP viability was analyzed at 1, 7, 14, 21, and 28 days, and ALP activity was analyzed every 7 days until 21 days to determine the effect of these bioactive molecule-releasing nanoparticles on the cytotoxicity and differentiation potential, respectively.

RESULTS

BSA-CSnpI and BSA-CSnpII presented distinct in vitro release profiles of BSA in a time-controlled manner. Cell viability was significantly enhanced over time in the presence of BSA-CSnpI and BSA-CSnpII (P < .01), when compared with BSA nonloaded CSnp. ALP activity was significantly higher (P < .01) in the presence of BSA-CSnpI after 3 weeks than in BSA-CSnpII.

CONCLUSIONS

BSA-loaded CSnps were synthesized and characterized in this study. Based on the physical/chemical interaction of BSA with CSnp (encapsulation or surface adsorption), different time-controlled release profiles were observed that influenced the ALP activity of SCAP in vitro. This study highlighted the potential of temporal-controlled bioactive molecule release technology in the differentiation of stem cells in dentin pulp regeneration.

In vitro evaluation of the effects of various additives and polymers on nerve growth factor microspheres

OBJECTIVE

To evaluate the effects of various additives or polymers on the in vitro characteristics of nerve growth factor (NGF) microspheres.

MATERIALS AND METHODS

NGF microspheres were fabricated using polyethylene glycol (PEG), ovalbumin (OVA), bovine serum albumin (BSA) or glucose as protein protectors, and poly(lactide-co-glycolide) (PLGA) or poly(lactic acid) (PLA)/PLGA blends as encapsulation materials.

RESULTS

Encapsulation efficiencies of the NGF microspheres with various additives or polymers were not more than 30%. A comparative study revealed that OVA was somewhat superior over others, and was thus chosen as the protective additive in subsequent experiments. Polymer analysis showed that NGF release from 1:1 PLA (η = 0.8):PLGA (75/25, η = 0.45) microspheres lasted for 90 d with a burst release rate of 12.7%. About 40% of the original bioactivity was retained on the 28th day, while 10% was left on the 90th day.

DISCUSSION AND CONCLUSION

The combination of OVA as an additive and the PLA/PLGA blend as the coating matrix is suitable for encapsulation of NGF in microspheres for extended release.