Hollow mesoporous
silica microsphere (HMSM) particles are one of the most promising
vehicles for efficient drug delivery owing to their large hollow interior
cavity for drug loading and the permeable mesoporous shell for controlled
drug release. Here, we report an easily controllable aerosol-based
approach to produce HMSM particles by continuous spray-drying of colloidal
silica nanoparticles and Eudragit/Triton X100 composite (EUT) nanospheres
as templates, followed by template removal. Importantly, the internal
structure of the hollow cavity and the external morphology and the
porosity of the mesoporous shell can be tuned to a certain extent
by adjusting the experimental conditions (i.e., silica to EUT mass
ratio and particle size of silica nanoparticles) to optimize the drug
loading capacity and the controlled-release properties. Then, the
application of aerosol-synthesized HMSM particles in controlled drug
delivery was investigated by loading amoxicillin as an antibiotic
compound with high entrapment efficiency (up to 46%). Furthermore,
to improve the biocompatibility of the amoxicillin-loaded HMSM particles,
their surfaces were functionalized with poly(allylamine hydrochloride)
and alginate as biocompatible polymers via the layer-by-layer assembly.
The resulting particles were evaluated toward Escherichia
coli (Gram-negative) bacteria and indicated the bacterial
inhibition up to 90% in less than 2 h. Finally, we explored the versatility
of HMSMs as drug carriers for pancreatic cancer treatment. Because
the pH value of the extracellular medium in pancreatic tumors is lower
than that of the healthy tissue, chitosan as a pH-sensitive gatekeeper
was grafted to the HMSM surface and then loaded with a pro-apoptotic
NCL antagonist agent (N6L) as an anticancer drug. The obtained particles
exhibited pH-responsive drug releases and excellent anticancer activities
with inhibition of cancer cell growth up to 60%.
We present a facile approach toward in situ coating of various inorganic semiconductor nanoparticles with a polymer shell by aerosol-photopolymerization.
With the decline in oil discoveries over recent decades, it is believed that enhanced oil recovery (EOR) technologies will play a key role to meet energy demand in the coming years. Polymer flooding is used commonly worldwide as an EOR process. In this work, we propose the synthesis of protected polyacrylamide (PAM) nanoparticles (PPNs) with a hydrophobic polystyrene (PSt) shell by one‐pot two‐step inverse emulsion polymerization, in which the PSt shell was created by surface polymerization. The shell protects the active PAM chains from premature degradation caused by the harsh environment in the reservoirs, controls the release of the chains as rheological modifiers, and additionally, it provides the chains with prolonged stability. The time‐dependent release of the PPNs promotes the effectiveness of the PPNs as viscosity modifiers, as the maximum viscosity enhancement is achieved at longer residence times in the reservoirs. This can be up to 30 days, and the released polymer maintained its activity. Under conditions of high salinity (total dissolved solids=178 082 mg L−1), temperatures up to 90 °C, and shear rates up to 1000 s−1, PPNs have shown superior properties, such as elastic modulus, shear rate behavior, viscosity loss, and sand adsorption over PAM, whereas the areal sweep efficiency of PPNs is similar to that of PAM and higher than that of conventional water flooding. All of this makes PPNs promising candidates for polymer‐enhanced oil recovery.
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