Rectorite-intercalated nanoparticles for improving controlled release of doxorubicin hydrochloride

Green Chemistry Principles for Nano- and Micro-Sized Hydrogel Synthesis

The growing demand for drug carriers and green-technology-based tissue engineering materials has enabled the fabrication of different types of micro- and nano-assemblies. Hydrogels are a type of material that have been extensively investigated in recent decades. Their physical and chemical properties, such as hydrophilicity, resemblance to living systems, swelling ability and modifiability, make them suitable to be exploited for many pharmaceutical and bioengineering applications. This review deals with a brief account of green-manufactured hydrogels, their characteristics, preparations, importance in the field of green biomedical technology and their future perspectives. Only hydrogels based on biopolymers, and primarily on polysaccharides, are considered. Particular attention is given to the processes of extracting such biopolymers from natural sources and the various emerging problems for their processing, such as solubility. Hydrogels are catalogued according to the main biopolymer on which they are based and, for each type, the chemical reactions and the processes that enable their assembly are identified. The economic and environmental sustainability of these processes are commented on. The possibility of large-scale processing in the production of the investigated hydrogels are framed in the context of an economy aimed at waste reduction and resource recycling.

Natural polysaccharides based self-assembled nanoparticles for biomedical applications - A review

In recent years, nanoparticles (NPs) derived from the self-assembly of natural polysaccharides have shown great potential in the biomedical field. Here, we described several self-assembly modes of natural polysaccharides in detail, summarized the natural polysaccharides mostly used for self-assembly, and provided insights into the current applications and achievements of these self-assembled NPs. As one of the most widespread substances in nature, most natural polysaccharides exhibit advantages of biodegradability, low immunogenicity, low toxicity, and degradable properties. Therefore, they have been fully explored, and the application of chitosan, hyaluronic acid, alginate, starch, and their derivatives has been extensively studied, especially in the fields of biomedical. Polysaccharides based NPs were proved to improve the solubility of insoluble drugs, enhance tissue target ability and realize the controlled and sustained release of drugs. When modified by hydrophobic groups, the amphiphilic polysaccharides can self-assemble into NPs. Other driven forces of self-assembly include electrostatic interaction and hydrogen bonds. Up to the present, polysaccharides-based nanoparticles have been widely applied for tumor treatment, antibacterial application, gene therapy, photodynamic therapy and transporting insulin.

Polyaspartic acid-anchored mesoporous silica nanoparticles for pH-responsive doxorubicin release

Background

Nanotechnology-based drug delivery systems exhibit promising therapeutic efficacy in cancer chemotherapy. However, ideal nano drug carriers are supposed to be sufficiently internalized into cancer cells and then release therapeutic cargoes in response to certain intracellular stimuli, which has never been an easy task to achieve.

Objective

This study is to design mesoporous silica nanoparticles (MSNs)-based pH-responsive nano drug delivery system that is effectively internalized into cancer cells and then release drug in response to lysosomal/endosomal acidified environment.

Methods

We synthesized MSNs by sol-gel method. Doxorubicin (DOX) was encapsulated into the pores as a model drug. Polyaspartic acid (PAsA) was anchored on the surface of mesoporous MSNs (P-MSNs) as a gatekeeper via amide linkage and endowed MSNs with positive charge.

Results

In vitro release analysis demonstrated enhanced DOX release from DOX-loaded PAsA-anchored MSNs (DOX@P-MSNs) under endosomal/lysosomal acidic pH condition. Moreover, more DOX@P-MSNs were internalized into HepG2 cells than DOX-loaded MSNs (DOX@MSNs) and free DOX revealed by flow cytometry. Likewise, confocal microscopic images revealed that DOX@P-MSNs effectively released DOX and translocated to the nucleus. Much stronger cytotoxicity of DOX@P-MSNs against HepG2 cells was observed compared with DOX@MSNs and free DOX.

Conclusion

DOX@P-MSNs were successfully fabricated and achieved pH-responsive DOX release. We anticipated this nanotherapeutics might be suitable contenders for future in vivo cancer chemotherapeutic applications.

Design of diversified self-assembly systems based on a natural rosin-based tertiary amine for doxorubicin delivery and excellent emulsification

A novel rosin-based ester tertiary amine (RETA) with three hydrophilic groups and a rigid hydrophobic group was synthesized from rosin by Diels-Alder addition, acylation and esterification reactions. RETA was characterized by infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (¹³C NMR). Results from testing surface tension, zeta potential, and transmission electron spectroscopy showed that RETA had unique pH responsiveness. RETA self-assembled into worm-like micelles, spherical micelles 130 nm in diameter and big spherical worm-like aggregates with diameter of 2 μm at pH = 5.76, 8.04 and 9.38, respectively. The critical micelle concentration (CMC) of RETA was 0.42 mmol/L, and the surface tension at CMC (γ_cmc) was 38.73 mN/m when pH was 8.04. The RETA had a potential application in delivering doxorubicin hydrochloride (DOX) due to the pH responsiveness. Self-assembly mixed systems of RETA and rosin-based phosphoric acid (DDPD) were designed to improve emulsification. The mixed systems had obvious synergistic effects and unexpected emulsification. The γ_cmc and CMC of mixtures were 41.74 mN/m and 0.20 mmol/L, the size of mixture micelles increased up to 300 nm in the optimum molar ratio of RETA/DDPD (7:3) by TEM and cryo-TEM. It was worth noting that the mixture system formed vesicles in the RETA/DDPD molar ratio of 5:5. The stability time of emulsion with RETA and DDPD as emulsifier were only 63 s and 52 s respectively, but the stability time increased to 234 s in the optimum molar ratio. In addition, the formation mechanisms of micelles at different pH and in various mixtures were discussed in detail. What's more, cytotoxicity results showed that the toxicity of RETA was lower significantly than that of lecithin, a food ingredient in egg yolk and soybean. The cell viability was more than 83% in the high concentration of RETA (4000 μg/ml).

Alternative foaming agents for topical treatment of ulcerative colitis

Approximately 907,000 Americans currently suffer from ulcerative colitis, a condition characterized by inflammation of the large intestine or rectum. Treatment of this disease often includes anti-inflammatory medication or immunosuppressants. Here foams are an attractive delivery platform, offering relatively high bioavailability, low systemic exposure, and improved patient comfort. However, the surfactants that generate these foams may adversely affect the diseased mucosa. Therefore, this project evaluated two alternative surfactants for use in topical drug delivery platforms: sodium caseinate and l-α-phosphatidylcholine. Both were compared to the biocompatible surfactant Pluronic^® F-127 using stability and density tests, and biocompatibility tests performed on mini-guts. Sodium caseinate foams were less stable but denser than Pluronic^® foams; however, they exhibited an unexpectedly low shelf-life. l-α-phosphatidylcholine was an unsuccessful primary foaming agent owing to poor foamability at low concentrations. Mini-gut growth rates were not significantly altered by surfactants, while morphology and an MTT assay identified Pluronic^® as the most biocompatible surfactant at higher concentrations. These results clarify the possible challenges that the tested surfactants may present in topical delivery platforms and show the relevance of permeability to tissue-surfactant interaction tests. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1448-1456, 2018.