Drug release kinetics of pH-responsive microgels of different glass-transition temperatures

Methacrylic acid based microgels and hybrid microgels

Methacrylic acid based microgels have got much consideration in the last two decades because of their potential uses in different fields owing to their responsive behaviour towards external stimuli. Synthesis, properties and uses of methacrylic acid based microgels and their hybrids have been critically reviewed in this article. With minute change in external stimuli such as pH and ionic strength of medium, these microgels show quick swelling/deswelling reversibly. The methacrylic acid based microgels have been widely reported for applications in the area of nanotechnology, drug delivery, sensing and catalysis due to their responsive behaviour. A critical review of current research development in this field along with upcoming perception is presented here. This discussion is concluded with proposed probable future studies for additional growth in this field of research.

Protecting redesigned supercharged ferritin containers against protease by integration into acid-cleavable polyelectrolyte microgels

HYPOTHESIS

The application of ferritin containers as a promising drug delivery vehicle is limited by their low bioavailability in blood circulation due to unfavorable environments, such as degradation by protease. The integration of ferritin containers into the polymeric network of microgels through electrostatic interactions is expected to be able to protect ferritin against degradation by protease. Furthermore, a stimuli-responsive microgel system can be designed by employing an acid-degradable crosslinker during the microgel synthesis. This should enable ferritin release in an acidic environment, which will be useful for future drug delivery applications.

EXPERIMENTS

Nanoparticle/fluorophores-loaded ferritin was integrated into microgels during precipitation polymerization. The integration was monitored by transmission electron microscopy (TEM)² and fluorescence microscopy, respectively. After studying ferritin release in acidic solutions, we investigated the stability of ferritin inside microgels against degradation by chymotrypsin.

FINDINGS

About 80% of the applied ferritin containers were integrated into microgels and around 85% and 50% of them could be released in buffer pH 2.5 and 4.0, respectively. Total degradation of the microgels was not achieved due to the self-crosslinking of N-isopropylacrylamide (NIPAM). Finally, we prove that microgels could protect ferritin against degradation by chymotrypsin at 37 °C.

A novel multi-stimuli-responsive theranostic nanomedicine based on Fe3O4@Au nanoparticles against cancer

A novel multi-stimuli-responsive theranostic nanomedicine was designed and fabricated by the conjugation of a thiol end-capped poly(N-isopropylacrylamide-block-acrylic acid) (HS-PNIPAAm-b-PAA) onto Fe₃O₄@Au nanoparticles (NPs) followed by physical loading of doxorubicin hydrochloride (Dox) as a general anticancer drug. For this purpose, Fe₃O₄@Au NPs were fabricated through small Au nanolayer grown on larger magnetic NPs. A HS-PNIPAAm-b-PAA was synthesized through an atom transfer radical polymerization (ATRP) approach, and then conjugated with as-synthesized Fe₃O₄@Au NPs by Au-S bonding. The Dox loading capacity of the synthesized Fe₃O₄@Au/Polymer theranostic NPs was calculated to be 81%. The theranostic nanomedicine exhibited excellent in vitro drug release behavior under pH and thermal stimuli. The anticancer activity evaluation using MTT assay (against MCF7 cells) revealed that the fabricated Fe₃O₄@Au/Polymer has high potential as theranostic nanomedicine for cancer therapy of solid tumors. This nanosystem can also applied in photothermal therapy, hyperthermia therapy, and their combination with chemotherapy due to presence of gold and Fe₃O₄ nanomaterials in its structure.