Nanoparticles polymeric micelles

A large variety of drug delivery systems are described in the literature, such as liposomes (Torchilin, 2006), micro and nanoparticles (Kumar, 2000), polymeric micelles (Torchilin, 2006), nanocrystals (Muller et al., 2011), among others. Microparticles are usually classified as microcapsules or microspheres (Figure 8). Microspheres are matrix spherical microparticles where the drug may be located on the surface or dissolved into the matrix. Microcapsules are characterized as spherical particles more than Ipm containing a core substance (aqueous or lipid), normally lipid, and are used to deliver poor soluble molecules... 

Fig. 30 Types of nanocarriers for drug delivery, (a) Polymeric nanoparticles polymeric nanoparticles in which drugs are conjugated to or encapsulated in polymers, (b) Polymeric micelles amphiphilic block copolymers that form nanosized core-shell structures in aqueous solution. The hydrophobic core region serves as a reservoir for hydrophobic drugs, whereas hydrophilic shell region stabilizes the hydrophobic core and renders the polymer water-soluble.

To design BPA, various strategies have been followed by researchers particulate systems (such as liposomes formulated with NS-CA [17-19], nanoparticles [20], micelle [21] or emulsion [22]) or macromolecules (either polymeric [23,24] or monodisperse [25]). In the present article, we shall focus on monodisperse iodi-nated macromolecules, the most recent class of iodinated BPA published so far. 

Another possible form of administration that is under study is through the use of nanoparticles with diameters in the range of 200-400 nm, obtained through the formation of nanocrystals or by creating nanoscale structures that capture the biomolecules. Depending on the materials employed and the preparation method, distinct particles can be used nanoparticles, liposomes, polymeric micelles, ceramic nanoparticles, and dendrimers. 

It is useful, for reasons which are apparent in relation to movement of nanoparticles in vivo, to divide nanosystems into two types, hard and soft, although there are obviously intermediate situations. Hard systems, for example, polymeric nanoparticles and nanocapsules, nanosuspensions or nanocrystals, dendrimers, and carbon nanotubes are neither flexible nor elastic. Hard systems can block capillaries and fenestrae that have dimensions similar to the particles, whereas soft systems can deform and reform to varying degrees. Erythrocytes and many liposomes fall into this category and are thus better able to navigate capillary beds and tissue extracellular spaces. Soft systems include nanoemulsions (microemulsions) and polymeric micelles. 

Fig. 8.6 Mechanism of action of tribologically active additives in nanoparticle form (a) adsorption step for molecular and nanoparticulate species (b) destruction of the surface-modifying layer and (c) several nanoparticles in a polymeric micelle [57]...

Amphiphilic block copolymers self-organize in aqueous mixtures to form polymeric micelles having a core of the hydrophobic block and a shell of the hydrophilic block. The cores can absorb additional hydrophobic low molecular weight compounds. The shells can be cross-linked to form capsules that are much more physically robust than the original micelles, as shown in Figure 11.10 (15). The uncross-linked inner phase can be dissolved by a good solvent to produce hollow capsules or serve as a site for trapping metal nanoparticles as catalysts. 

Figure 6 (a) Schematic presentation of polymeric nanoparticles with weak acid (sulfonamide groups). The polymeric nanoparticles show good stabdity at pH 7.4 but are aggregated/shrunken near the tumor where the pH is below tumor pHg. (b) A schematic concept of anticancer drug release triggered by the change of hydrophobic core solubility in the polymeric micelle. 

Fig. 1 Various polymeric drug carriers (a) conjugates, (b) dendrimers, (c) nanoparticles, (d) micelles, (e) nanogels, (f) polymersomes...

Simply modulating Pgp appears to be an extreme challenge in overcoming MDR in a clinical setting. As an alternative to Pgp modulators alone, various nanosized drug carriers have been tested to circumvent MDR in vitro and in vivo. Carriers include liposomes [216], alkylcyanoacrylate [217], nanoparticles [218], polymeric micelles of Pluronics [219] and other amphiphihc block copolymers [220], and PLGA nanoparticles [221]. 

Several approaches have recently been developed that directly apply natural architectures for artificial chanical reactions, some of which are detailed in different chapters of this book. Although not classified as homogeneous catalysis, the reduction of metal salts inside nanoreactors could be the first step on the way to reactivity with the corresponding metal coUoids or nanoparticles in e.g. hydrogenation reactions. A variety of carrier systems have been studied lately, including virus capsids, polymeric micelles, miniemulsions and hollow core-shell particles, as nanoreactors and hosts for the synthesis and encapsnlation of well-defined, stable nanoparticles. ... 

In our recent smdies, we focused on several complicating factors arising in studies of nanoparticles of a non-negligible size (e.g., polymeric micelles, vesicles) that can carry several fluorescent labels. When the dimensions of such particles become comparable to the typical dimensions of the effective volume (coi, (O2), the correlated motion of the fluorophores located on a single particle affects the shape of the autocorrelation function. Recently, an approximate expression for the FCS autocorrelation function of diffusing particles of finite size has been derived by Wu et al. [85]. They have shown that the autocorrelation function of uniformly labeled spherical particles can be expressed in a form similar to (12) where the diffusion time, concentration, and dimensions of the active volume are replaced by corresponding apparent quantities that depend on the particle size. Qualitatively, the same results were obtained in our computer simulations, which are discussed later (see Sect. 4.3). 

Nano-sized objects may be different in physical nature, e.g. perfectly elastic inorganic nanoparticles, viscoelastic polymeric nanoparticles, viscous micelles however, all injectable nano-systems share a common macroscopic property under the conditions employed during the application, they flow, i.e. they are... 

Bakalova and co-workers reported the synthesis of a 17 nm nanoparticle with a quantum dot (QD) core and a silica sheU. The encapsulation of the QD by silica involved the assembly of a polymerized micelle around the QD followed by the formation of polymerized silane shell around the precursors (Figure 7.1). By avoiding... 

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