Nanogels in drug delivery

I 0 Hydrophilic Colloidal Networks (Micro- and Nanogels) in Drug Delivery and Diagnostics... 

MICRO- AND NANOGELS IN DRUG DELIVERY 16.4.1 Biodegradable Micro- and Nanogels... 

As mentioned above, the preparation of nanogels by addition reactions of functional macromolecular precursors is mainly used for biomedical applications. Thus, the choice of synthetic precursors for microgel formation is restricted to biocompatible materials. Moreover, as most applications are in drug delivery, the molecular weight of the gel precursors should be below the threshold for renal clearance, a value that depends on the molecular architecture and chemical nature of the polymer but that is usually smaller than 30kDa, which is set as the limit for linear PEG [97], Polymers that are mostly used and thus presented in more detail here are PEG, poly(glycidol) (PG), and polyethylene imine) (PEI). 

Oh, J. K., Lee, D. I., and J. M. Park. 2009. Biopolymer-based microgels/nanogels for drug delivery applications. Progress in Polymer Science 34 1261-1282. 

Subhash, D., Mody, H., Baneijee, R., Bahadur, D., Srivastava, R., 2011. Poly(N-isopropylacrylamide)-based pol3mer nanogels for drug delivery applications. In 11th IEEE International Conference on Nanotechnology Portland Marriott, Portland, Oregon, USA, August 15—18, pp. 1741—1744. 

While nanogel synthesis is attracting increasing attention for its potential in drug delivery, synthesis is usually achieved in bulk solution either from polymer precursors or heterogeneous polymerization from monomers rather than synthesis in a nanofluidic or microfluidic channel. However, nanogel particles can be incorporated into the interior of microspheres within a microfluidic environment. 

MPEG-armed PPE core-cross-linked nanogels have been prepared by a one-step ROP, using MPEG as the arm to polymerize a difunctional phosphate monomer, namely 3,6-dioxaoctan-l,8-diyl bis(ethylene phosphate) (TEGDP), to obtain the core-cross-linked star polymer.This synthesis procedure is surfactant-free, and the core material is constituted of a PPE which has been demonstrated to be biodegradable and which may have wide applications in drug delivery. 

Oh JK, Siegwart DJ, Lee HI, et al. (2007) Biodegradable nanogels prepared by atom transfer radical polymerization as potential drug delivery carriers synthesis, biodegradation, in vitro release, and bioconjugation. J Am Chem Soc 129 5939-5945... 

FIGURE 54.23 A schematic representation of inverse miniemulsion or microemulsion polymerization for the preparation of nanometer-sized particles of water-soluble and water-swellable polymers as well as cross-linked particles in the presence of cross-linkers. (Reprinted from Polymer, 50(19), Oh, J.K., Bencherif, S.A., and Matyjaszewski, K., Atom transfer radical polymerization in inverse miniemulsion A versatile route toward preparation and functionalization of microgels/nanogels for targeted drug delivery applications, 4407-4423. Copyright 2009, with permission from Elsevier.)... 

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