AIMTo prepare recombinant human tumor necrosis factor-alpha (rHuTNF-alpha) -loaded stealth nanoparticles with different PEG chain lengths and sizes, and investigate the stability of nanoparticle suspensions.

METHODSThe poly( MePEG cyanoacrylate-co-hexadecyl cyanoacrylate) (MePEG-PHDCA) and poly(hexadecyl cyanoacrylate) (PHDCA) were synthesized and characterized with Fourier transform infrared spectrum (FTIR), 1HNMR, 13CNMR and gel permeation chromatography (GPC). Uniform design was used to optimize the entrapment efficiency. The nanoparticle suspensions were stored at 2 - 8 degrees C for 4 weeks, and the particle size evolution was studied.

RESULTSFTIR, 1HNMR and 13CNMR were consistent with the structures of MePEG-PHDCA and PHDCA whose polydispersity indexes were all less than 1.1, indicating narrow distributions. The entrapment efficiency of all nanoparticles was satisfactory. The three different mean diameters of MePEG-PHDCA and PHDCA nanoparticles were about 80 nm, 170 nm and 240 nm, separately. The nanoparticle suspensions maintained their sizes at 2 - 8 degrees C for 4 weeks

CONCLUSIONMePEG-PHDCA with three different molecular weight MePEG and PHDCA were synthesized successfully. There are negligible aggregations and bulk or surface erosion as for both stealth MePEG-PHDCA and conventional PHDCA nanoparticles in distilled water.