Nanoparticles drug release control

Na K, Park KH, Kim SW et al (2000) Self-assembled hydrogel nanoparticles from curdlan derivatives characterization, anti-cancer drug release and interaction with a hepatoma cell line (HepG2). J Control Release 69 225-236... 

Lin YH, Sonaje K, Lin KM et al (2008) Multi-ion-crosslinked nanoparticles with pH-responsive characteristics for oral delivery of protein drugs. J Control Release 132 141-149... 

Jenning, V., Schafer-Korting, M. and Gohla, S., Vitamin A-loaded solid hpid nanoparticles for topical use drug release properties. J. Control. Release, 66, 115-26, 2000. 

The very large absorption cross-sections of Au nanoparticles give rise to photothermal effects, that is, an increase in local temperature upon plasmon resonance excitation. The concept of Au nanoparticles as photothermal transducers has inspired numerous efforts to develop biomedical applications such as localized hyperthermal therapy,63-65 photothermal contrast agents,66 and optothermally controlled drug release,67-69 and also novel platforms for information storage.70... 

Keywords. Controlled drug release, Hydrogels, Microparticles, Nanoparticles, Niosomes, Tablets, Transdermal... 

Following a study of physical properties of these nanoparticles, further research focused on defining stoichiometric coefficients of reactants involved in a batch system. This study was undertaken to gain a better understanding of the assembly process for producing nanoparticles, mechanisms involved in drug release and control of their release. This process is then extensively compared with similar products on the market and reported in the literature. 

In order to achieve a sustained drug release and a prolonged therapeutic activity, nanoparticles must be retained in the cul-de-sac and the entrapped drug must be released from the particles at a certain rate. If the release is too fast, there is no sustained release effect. If it is too slow, the concentration of the drug in the tears might be too low to achieve penetration into the ocular tissues [208]. The major limiting issues for the development of nanoparticles include the control of particle size and drug release rate as well as the formulation stability. 

Paasonen, L., Laaksonen, T., Johans, C., Yliperttula, M., Kontturi, K. and Urtti, A. (2007) Gold nanoparticles enable selective light induced drug release from liposomes. Journal of Controlled Release, 122, 86-93. 

The hydrophobic core of nanoparticles is mostly made of solid glassy polymers such as polycaprolactone, polylactide, and their random copolymers. Drags are physically trapped and dispersed in the core. Except for the initial burst release period, the drug release from the solid nanoparticle cores tends to be a slow diffusion-controlled process [126]. Thus, nanoparticles responding to the acidic environments of tumor intercellular fluid or intracellular acidic compartments have been developed for fast drug release. 

Williams, J. Lansdown, R. Sweitzer, R. Romanowski, M. LaBell, R. Ramaswami, R. Unger, E. Nanoparticle drug delivery system for intravenous delivery of topoisomerase inhibitors. J. Control. Release 2003, 91, 167-172. 

Besides liposomes, polymeric nanoparticles may be used as effective drug carrier systems using cytotic pathways. Particle size and polymeric composition help control particle degradation and drug release. Recently, it was shown in a rat study that polybutylcyanoacrylate nanoparticles, which had been surface coated with polysorbate 80, exhibited a 20-fold higher uptake into brain capillary endothelial cells compared to noncoated nanoparticles [17]. It is assumed that association of lipoproteins at the surface triggers the endocytotic uptake of the nanoparticles. 

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