Novel pH-Responsive Nanoparticles

Abstract

In this work we report a new type of pH-responsive micelle-like nanoparticle. Reversible nanoscale structures are formed in solutions of a pH-sensitive hydrophobic polyelectrolyte, poly( N-methacryloyl- l-valine) or poly( N-methacryloyl- l-phenylalanine), and nonionic surfactant (Brij 98) in the presence of hydrochloric acid. The influence of composition and pH on particles size and shape was investigated by a variety of methods. An entity's size and polydispersity could be varied in a broad range making them a perspective candidate as a drug carrier. Unlike the case of typical micelles, our results indicate the presence of cavities in the formed particles. A hypothetical model of a nanoparticle and mechanism of formation are proposed.

Smart polymers in drug delivery systems on crossroads: Which way deserves following?

“…In this process the proton of the acid plays a crucial role -upon deprotonation (neutralization) of the acid the complex disassembles and dissolves. We have shown [120,121] such behavior for the poly(N-methacryloyl amino acids) and poly(N-methacryloyl oligopeptides) + detergents. Details of this behavior are adjustable by hydrophobicity and sterical aspects.…”

“…Similarly to thermoresponsive polymers, an essential property for the bioapplicability of the pHresponsivity is the sharpness of the pH-driven transition. The polymers described in our publications [120,121] are examples of systems with a very narrow transition (in a range of a few tenths of pH) between the dissolved and collapsed state, as shown in Fig. 5.…”

“…6c for structure) and their interactions with the nonionic surfactant Brij98 were analyzed [120,121]. Nanoparticles of a narrow size distribution have been obtained that displayed reversible pH-dependent transition behavior (i.e.…”

“…Intensity of scattered light I S as a function of pH from an aqueous solution of poly(N-methacryloyl-L-valine) sodium salt[121]. Examples of pH-responsive polymers studied for bioactive component delivery: Eudragit Ò L 100 (copolymer of methacrylic acid and methyl methacrylate, 1:1) (a), poly(propylacrylic acid) (b), poly(N-methacryloyl glycyl-L-leucine) (c), poly(L-histidine) (d).…”

Polymeric Nanoparticles Stabilized by Surfactants: Controlled Phase Separation Approach

“…poly(N-methacryloyl-L-valine) (pNMV), the extent of macrophase separation was controlled by the amphiphilic molecule Brij98. We have shown previously (Filippov et al, 2008;Filippov et al, 2010) that in a certain range of concentration and composition of the polymer/amphiphile system very monodisperse particles with size ca. 50 nm could be reproducibly prepared after a change of pH from 7 to 3.5.…”