Thermally responsive polymeric micelles self‐assembled by amphiphilic polyphosphazene with poly(N‐isopropylacrylamide) and ethyl glycinate as side groups: Polymer synthesis, characterization, and in vitro drug release study

Abstract

Thermally responsive amphiphilic poly(N-isopropylacrylamide) (PNIPAm)-grafted-polyphosphazene (PNIPAm-g-PPP) was synthesized by stepwise cosubstitution of chlorine atoms on polymer backbones with amino-terminated NIPAm oligomers and ethyl glycinate (GlyEt). Polymer structure was confirmed by FT-IR, (1)H NMR, elemental analysis, and GPC. The thermosensitivity of PNIPAm-g-PPP aqueous solution was investigated by turbidity method. The lower critical solution temperature (LCST) of PNIPAm-g-PPP was observed to be approximately 30 degrees C in water, while it was 24 degrees C in 0.1M PBS (pH 7.4). Micellization behavior of PNIPAm-g-PPP in aqueous solution was characterized by fluorescence probe technique, TEM, and DLS. The critical micelle concentration (CMC), thus, determined was 0.0187 g/L. Both TEM and DLS measurement suggested that the diameter of micelles was approximately 190 nm at 20 degrees C. Diflunisal (DIF)-loaded micelles were prepared by dialysis method. In vitro release test at various temperatures was also performed to study the effect of temperature on the drug release profiles. It was demonstrated that DIF release from PNIPAm-g-PPP micelles was slower at the temperature of 37 degrees C than that at 4 degrees C.

Self-assembled polyethylenimine-graft-poly(ε-caprolactone) micelles as potential dual carriers of genes and anticancer drugs

“…Sample solutions for fluorescence investigation were prepared as described previously [23]. Briefly, a known amount of pyrene in THF was added to each of a series of 10 ml vials and THF was evaporated.…”

The Influence of Drug Loading on Caveolin-1 Mediated Intracellular Internalization of Doxorubicin Nanomicelles in vitro

“…The SMA micelle gives the potential to achieve a wide range of drug loading depending on the characteristics privileges, as this parameter will also precondition a slow or a fast release of the drug from the micelle [19][20][21]. This system differs from most micellar sytem engineered where the drug release rate shows pronounced biphasic characteristics [22][23][24][25]. We generated three SMA micelles with doxorubicin loadings of 4.4, 14.5 or 28.4% (Table 1).…”

Physicochemical characterization, in vitro, and in vivo evaluation of indomethacin‐loaded nanocarriers self‐assembled by amphiphilic polyphosphazene

“…Amphiphilic copolymer PNIPAAm/EtGly-PPP was synthesized as described previously. 24,25,28 The other reagents were commercially available and used without further purification.…”

“…[22][23][24] Preparation, in vitro and in vivo evaluation of drug-loaded micelles based on this type of amphiphilic polyphosphazenes was also performed recently. 25,26 The aim of this work was to develop an injectable drug carrier for local delivery of indomethacin, a hydrophobic nonsteroidal antiinflammatory drug, to inflamed joint in two rat models of arthritis. In addition to physicochemical characterization and in vitro evaluation of micelles containing indomethacin (IND) based on polyphosphazene with PNIPAAm and ethyl glycinate (EtGly) as side groups (PNIPAAm/EtGly-PPP), in vivo pharmacokinetic and pharmacodynamic studies were carried out.…”