Polyelectrolyte microcapsules are one of the most successful developments in the direction of target drug delivery. Nevertheless, to encapsulate low molecular weight compounds and to deliver the targeted drugs it is necessary to modify the surface of the microcapsules. Silica nanostructures obtained as result of hydrolysis of (3-Aminopropyl)- triethoxysilane (APTES) were used for the modification of the microcapsules. This material shows no toxic effect on cells and is capable of biodegradation. Amino-groups in the structure of APTES make it possible for further direct bioconjugation.
Small drug molecules are widely developed and used in the pharmaceutical industry. In the past few years, loading and delivering such molecules using polymer-shell colloidosomes has attracted interest. Traditional polymer capsules fail to encapsulate low-molecular-weight materials for long times, since they are inherently porous and permeable for small molecules. In this paper, we report a method for encapsulating an anticancer drug with small molecule weight, for cell viability tests. The silver-coated colloidosomes are prepared by making an aqueous core capsule with a polymer shell and then adding AgNO3, surfactant, and l-ascorbic acid to form a second shell. The capsules are impermeable and can be triggered using ultrasound. We propose to use the capsules as drug carriers. The silver demonstrates a low cytotoxicity for up to 10 capsules per cell. After the silver shells are triggered by ultrasound, the released doxorubicin, the broken silver fragments, and the doxorubicin loading on the capsule surface all kill cells. The results demonstrate a nonpermeable silver-shell microcapsule with ultrasound sensitivity for potential medical applications.
This work aims to improve the rheological properties of partially hydrolyzed polyacrylamide (HPAM) for enhanced oil recovery by using silica (or silicon dioxide, SiO2) nanoparticles (NPs). Novel aqueous HPAM-based SiO2 nanocomposites were formulated, and their rheological properties were investigated under different salinities, temperatures, and aging times. The results show that the inclusion of silica NPs significantly improved the viscosity and viscoelastic properties of HPAM especially under high temperature and high salinities. The NP/HPAM hybrid showed an impressive thermal stability at T = 80 °C after 12 days, and the viscosity reached ∼5 times that of HPAM at 0.8 wt % NP loading. The Fourier transform infrared spectral data confirmed that the formation of a hydrogen bond between the carbonyl groups in HPAM and the silanol functionalities on the surface of silica NPs contributed to the improved performance. The oscillation test indicated that seeding SiO2 remarkably facilitated the cross-links among polymer molecules and made the hybrids more elastically dominant. For a given HPAM concentration, it was observed that there was a critical nanoparticle concentration, which may indicate the absorption status of SiO2 NPs onto HPAM, and the salinity also affected the viscosity value.
Microcapsules that can be efficiently loaded with small molecules and effectively released at the target area through the degradation of the capsule shells hold great potential for treating diseases. Traditional biodegradable polyelectrolyte (PE) capsules can be degraded by cells and eliminated from the body but fail to encapsulate drugs with small molecular weight. Here, we report a poly-l-arginine hydrochloride (PARG)/dextran sulfate sodium salt (DEXS)/silica (SiO2) composite capsule that can be destructed in cells and of which the in situ formed inorganic SiO2 enables loading of small model molecules, Rhodamine B (Rh-B). The composite capsules were fabricated based on the layer-by-layer (LbL) technique and the hydrolysis of tetraethoxysilane (TEOS). Capsules composed of nondegradable PEs and SiO2, polyllamine hydrochloride (PAH)/poly(sodium 4-styrenesulfonate) (PSS)/silica (the control sample), were prepared and briefly compared with the degradable composite capsules. An intracellular degradation study of both types of composite capsules revealed that PARG/DEXS/silica capsules were degraded into fragments and lead to the release of model molecules in a relatively short time (2 h), while the structure of PAH/PSS/silica capsules remained intact even after 3 days incubation with B50 cells. Such results indicated that the polymer components played a significant role in the degradability of the SiO2. Specifically, PAH/PSS scaffolds blocked the degradation of SiO2. For PARG/DEXS/silica capsules, we proposed the effects of both hydrolytic degradation of amorphous silica and enzymatic degradation of PARG/DEXS polymers as a cell degradation mechanism. All the results demonstrated a new type of functional composite microcapsule with low permeability, good biocompatibility, and biodegradability for potential medical applications.
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