Nanocapsules For Drug Delivery Research Articles

Crosslinked Polymeric Nanocapsules Via Surface-initiated Atom Transfer Radical Polymerization from SiO2 Nano-templates

The aim of the present work was to develop the crosslinked polymeric nanocapsules for drug delivery from the SiO2 nano-templates via surface-initiated atom transfer radical polymerization (SI-ATRP) technique. The crosslinked polymeric nanocapsules were fabricated via the SI-ATRP of 2-hydroxyethyl acrylate (HEA) from initiator modified silica nano-templates. After the hydroxyl side-groups of the polymer grafted silica nanoparticles (SN@PHEA) were crosslinked with hexamethylene diisocyanate (HDI), the silica templates encapsulated in the crosslinked polymer shells were removed by being etched with HF to produce the crosslinked polymeric nanocapsules. The diameter of the polymeric nanocapsules is in the range of 20–40 nm, characterized by transmission electron microscopy (TEM).

Structural Stability of Vault Particles

Vaults, at 13 MDa, are the largest ribonucleoprotein particles known. In vitro, expression of the major vault protein (MVP) alone in Sf9 insect cells results in the production of recombinant particles with characteristic vault structure. With the ultimate goal of using recombinant vaults as nanocapsules for the delivery of biomolecules, we have employed a variety of spectroscopic techniques (i.e., circular dichroism, fluorescence spectroscopy, and light scattering) along with electron microscopy, to characterize the structural stability of vaults over a wide range of pH (3-8) and temperature (10-90 degrees C). Ten different conformational states of the vaults were identified over the pH and temperature range studied with the most stable region at pH 6-8 below 40 degrees C and least stable at pH 4-6 above 60 degrees C. A unique intermediate molten globulelike state was also identified at pH 6 and approximately 55 degrees C. EM imaging showed the opening of intact vaults into flowerlike structures when transitioning from neutral to acidic pH. This information has potential use in the development of recombinant vaults into nanocapsules for drug delivery since one mechanism by which therapeutic agents entrapped in vaults could be released is through an opening of the intact vault structure.

Carbon nanotubes as drug delivery nanocapsules

Nanotubes have been proposed as targeted drug delivery nanocapsules which may realize the “magic bullet” concept and promise many advantages over current procedures. The question arises as to whether a nanotube drug carrier could be engineered so that it is energetically favourable for the drug molecule to be encapsulated, and then once inside the cell, energetically favourable to be ejected. In other words, we need to understand and accurately predict the uptake and expulsion capacities of a particular carbon nanotube in association with the molecules of a particular drug. In this paper, for a carbon nanotube carrier, the concepts of an acceptance condition and the suction energy are used to determine the suction behaviour of cisplatin, a platinum-based anticancer drug. It is shown theoretically using elementary mechanics and applied mathematical modelling techniques that for cisplatin to be accepted, the carbon nanotube must have a radius of at least 4.785 Å, and that the maximum suction energy occurs when the carbon nanotube radius is 5.27 Å.