Multi‐responsive polymeric microcontainers for potential biomedical applications: synthesis and functionality evaluation

Temperature and pH responsive poly(N‐isopropylacrylamide‐co‐methacrylic acid) (P(NIPAAm‐co‐MAA)) microcontainers with encapsulated magnetic nanoparticles in the shell were prepared by a two‐stage distillation precipitation polymerization. PMAA@Fe₃O₄/P(NIPAAm‐co‐MAA) core–shell nanoparticles were synthesized by the second‐stage polymerization of NIPAAm, MAA and N, N′‐methylenebisacrylamide as crosslinker in the presence of magnetic nanoparticles and PMAA as core. These novel triple‐functional microcontainers were prepared by selective removal of the PMAA core in water. Daunorubicin hydrochloride (DNR) was loaded into the microcontainers and the release profile was studied by UV–visible spectroscopy. The synthesized nanostructures were characterized with transmission and scanning electron microscopy, X‐ray diffraction and Fourier transform infrared spectroscopy. The magnetic properties were evaluated by vibrating sample magnetometry. The shrink and swelling behavior was studied by dynamic light scattering. Copyright © 2012 Society of Chemical Industry     

Direct electrochemical generation of conducting polymer microcontainers on silicon substrate

Polypyrrole microcontainers with morphology like bowls, cups, goblets and bottles have been electrochemically generated by direct oxidation of pyrrole on a p‐type silicon wafer in aqueous solution of camphorsulfonic acid. The well‐ordered microcontainers stand upright on the working electrode surface and changing the electrochemical polymerization conditions can easily control their morphological features. The growing process of microcontainers was studied by scanning electron microscopy. The microcontainers were characterized as being made of polypyrrole films in the doped state by Raman and IR spectroscopies. Copyright © 2004 Society of Chemical Industry     

Microscopic Cascading Devices for Boosting Mucus Penetration in Oral Drug Delivery—Micromotors Nesting Inside Microcontainers

In the case of macromolecules and poorly permeable drugs, oral drug delivery features low bioavailability and low absorption across the intestinal wall. Intestinal absorption can be improved if the drug formulation could be transported close to the epithelium. To achieve this, a cascade delivery device comprising Magnesium-based Janus micromotors (MMs) nesting inside a microscale containers (MCs) has been conceptualized. The device aims at facilitating targeted drug delivery mediated by MMs that can lodge inside the intestinal mucosa. Loading MMs into MCs can potentially enhance drug absorption through increased proximity and unidirectional release. The MMs will be provided with optimal conditions for ejection into any residual mucus layer that the MCs have not penetrated. MMS confined inside MCs propel faster in the mucus environment as compared to non-confined MMs. Upon contact with a suitable fuel, the MM-loaded MC itself can also move. An in vitro study shows fast release profiles and linear motion properties in porcine intestinal mucus compared to more complex motion in aqueous media. The concept of dual-acting cascade devices holds great potential in applications where proximity to epithelium and deep mucus penetration are needed.     

Loading of Drug‐Polymer Matrices in Microreservoirs for Oral Drug Delivery

For major advances in microfabricated drug delivery systems (DDS), fabrication methods with high throughput using biocompatible polymers are required. Once these DDS are fabricated, loading of drug poses a significant challenge. Here, hot punching is presented as an innovative method for drug loading in microfabricated DDS. The microfabricated DDS are microcontainers fabricated in photoresist SU‐8 and biopolymer poly‐l ‐lactic‐acid (PLLA). Furosemide (F) drug is embedded in poly‐ε‐caprolactone (PCL) polymer matrix. This F‐PCL drug polymer matrix is loaded in SU‐8 and PLLA microcontainers using hot punching with >99% yield. Thus, it is illustrated that hot punching allows high‐throughput, parallel loading of 3D polymer microcontainers with drug‐polymer matrices in a single process step.

     

Rational Synthesis of Magnetic Thermosensitive Microcontainers as Targeting Drug Carriers

A new approach to the fabrication of magnetic thermosensitive microcontainers of Fe₃O₄ nanoparticles with poly(N‐isopropylacrylamide) walls is presented. The microcontainers undergo a temperature‐induced volume phase transition and present an impressive magnetic response. The microcontainers have a well‐defined structure with a narrow size distribution. The wall thicknesses of the microcontainers can be controlled according to requirements. Compared to other preparation methods, the process is simple and reproducible. The magnetic saturation of these microcontainers is high enough to meet most requirements of bioapplications. To further investigate the potential application of these microcontainers, they are tested as drug carriers, with the drug loading and releasing processes carefully studied. The drug encapsulation efficiency and drug content in the carriers are pH‐dependent, and the carriers have a maximal drug loading of about 50 wt% under alkaline conditions. The release of the drug from the microcontainers can be controlled by the environmental pH, temperature, and magnetic force.