Untitled

Abstract

The modification of surface properties of biodegradable poly(lactide-co- glycolide) (PLGA) and model polystyrene nanospheres by poly(lactide)-poly(ethylene glycol) (PLA:PEG) copolymers has been assessed using a range of in vitro characterization methods followed by in vivo studies of the nanospheres biodistribution after intravenous injection into rats. Coating polymers with PLA:PEG ratio of 2:5 and 3:4 (PEG chains of 5000 and 2000 Da. respectively) were studied. The results reveal the formation of a PLA:PEG coating layer on the particle surface resulting in an increase in the surface hydrophilicity and decrease in the surface charge of the nanospheres. The effects of addition of electrolyte and changes in pH on stability of the nanosphere dispersions confirm that uncoated particles are electrostatically stabilized, while in the presence of the copolymers, steric repulsions are responsible for the stability. The PLA:PEG coating also prevented albumin adsorption onto the colloid surface. The evidence that this effect was observed for the PLA:PEG 3:4 coated nanospheres may indicate that a poly(ethylene glycol) chain of 2000 Da can provide an effective repulsive barrier to albumin adsorption. The in vivo results reveal that coating of PLGA nanospheres with PLA:PEG copolymers can alter the biodistribution in comparison to uncoated PLGA nanospheres. Coating of the model polystyrene nanospheres with PLA:PEG copolymers resulted in an initial high circulation level, but after 3 hours the organ deposition data showed values similar to uncoated polystyrene spheres. The difference in the biological behaviour of coated PLGA and polystyrene nanospheres may suggest a different stability of the adsorbed layers on these two systems.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymph node localisation of biodegradable nanospheres surface modified with poloxamer and poloxamine block co‐polymers

“…A general reduction in zeta potential was observed when the nanospheres were coated with the block co-polymers. This is attributed to the masking of the inherent negative charge of the nanospheres (carboxyl groups in the polymer end groups [10]). The PEO chains bring about a shift in the shear plane to a distance further from the nanosphere surface [11].…”

Stealth Polycyanoacrylate Nanoparticles as Tumor Necrosis Factor-.ALPHA. Carriers: Pharmacokinetics and Anti-tumor Effects.

“…The same observations have been reported for PLGA-PLA : PEG coated nanoparticles. 28) Our experimental results showed that PEG-PHDCA nanoparticles could extend the half-life of rHuTNF-a to 7.42 h and obviously change the protein biodistribution in tissues, in particular, increase accumulation of rHuTNF-a in tumor. This result confirmed the idea of forming nanoparticles with a steric PEG barrier that would prevent their rapid uptake by MPS, improve circulatory half-life of rHuTNF-a and also contribute to the enhanced vascular permeability of tumors compared with normal tissues.…”

Solvent-Free Synthesis of New Bis(Benzimidazole-2-Alkylthio) Polyethylene Oxides Starting from Dithiols

“…In medicine, the polymer has been incorporated in several drugs such as oral sustainedrelease tablets [1][2][3][4][5] and ocular inserts. 6 in addition, it has been shown that particles with poly(ethylene oxide) surfaces have great potential as long circulating systems after intravenous administration [7][8][9][10][11] .…”