ABSTRACT
Arsenic trioxide (ATO) is an effective component of traditional Chinese medicine arsenic. The existing studies have shown its good inhibition and apoptosis ability on a variety of tumours. However, its toxicity and difficulties in the permeability into the blood brain barrier (BBB) has the limitation in the application of glioma treatment. Polyamide-amine dendrimer (PAMAM) is a synthetic polymer with many advantages, such as a good permeability, stability and biocompatibility. Additionally, the 5th generation of PAMAM is an ideal drug carrier due to its three-dimensional structure. In this study, the 5th generation of PAMAM co-modified with RGDyC and PEG, then confirmed by ¹H-NMR. The average particle size of nanoparticles was about 20 nm according to the nanoparticle size-potential analyser and transmission electron microscopy. release showed that the nanocarrier not only has the sustained release effect, but also some pH-sensitive properties. The cell results showed that PAMAM co-modified with RGDyC and PEGAM has a lower cytotoxicity than the non-modified group . Accordingly, the drug delivery system has a better anti-tumour effect across the blood brain barrier (BBB) , which further proves the tumour targeting of RGDyC.
ABSTRACT
OBJECTIVE: To study the effect of different graft ratios of PEG on the toxicity in vitro and cellular uptake of PAMAM G5 dendrimers. METHODS: Nuclear magnetic resonance (1H-NMR) and Fourier transform infrared (FT-IR) spectroscopy were used to confirm the structure of PEG-PAMAM G5 dendrimers with four different graft ratios. The particle size and Zeta potential of the nanoparticles were determined by nanoparticle size-Zeta potential analyzer. The toxicity in vitro,cellular uptake, and intracellular localization were tested by hemolysis assay,cytotoxicity assay,cellular uptake test,and laser scanning confocal microscope images,respectively. RESULTS: The particle sizes of dendrimers with PEG graft ratios of 7.8%,14.1%, 20.3%,and 24.2% were (17.05 ± 1.77), (20.77 ± 1.02),(21.68 ± 1.04),and (23.19 ± 0.54) nm,respectively. The Zeta potential decreased from (25.57 ± 1.37) mV of PAMAM G5 to (9.27 ± 0.40) mV of PEG31-PAMAM G5. In addition, the hemolytic toxicity and cytotoxicity of PAMAM G5 dendrimers also markedly decreased especially at high concentrations because of PEG modification. Moreover, the PEG-PAMAM G5 dendrimers with particle diameter of nearly 20 nm not only could be taken in by HBMEC cells, but also accumulated in the cell nucleus. CONCLUSION: Modification of PEG can greatly reduce the toxicity of PAMAM G5 dendrimers in vitro, and the higher the degree of modification, the more obvious is the attenuated effect. The PEG-PAMAM G5 dendrimers with particle diameter larger than 20 nm still can be taken in by HBMEC cells and accumulate in the cell nucleus, which provide a foundation for the further research using modified PEG-PAMAM G5 as a basic carrier for genes and nuclear targeting agents in nano medicine.
ABSTRACT
A novel targeting drug carrier (FA-BO-PAMAM) based on the PAMAM G5 dendrimer modified with borneol (BO) and folic acid (FA) molecules on the periphery and doxorubicin (DOX) loaded in the interior was designed and prepared to achieve the purposes of enhancing the blood-brain barrier (BBB) transportation and improving the drug accumulation in the glioma cells. 1H NMR was used to confirm the synthesis of FA-BO-PAMAM; its morphology and mean size were analyzed by dynamic light scattering (DLS) and transmission electron microscope (TEM). Based on the HBMEC and C6 cells, cytotoxicity assay, transport across the BBB, cellular uptake and anti-tumor activity in vitro were investigated to evaluate the properties of nanocarriers in vitro. The results showed that the nanocarrier of FA-BO-PAMAM was successfully synthesized, which was spherical in morphology with the average size of (22.28 ± 0.42) nm, and zeta potential of (7.6 ± 0.89) mV. Cytotoxicity and transport across the BBB assay showed that BO-modified conjugates decreased the cytotoxicity of PAMAM against both HBMEC and C6 cells and exhibited higher BBB transportation ability than BO-unmodified conjugates; moreover, modification with FA increased the total uptake of DOX by C6 cells and enhanced the cytotoxicity of DOX-polymer against C6 cells. Therefore, FA-BO-PAMAM is a promising nanodrug delivery system in employing PAMAM as a drug carrier and treatment for brain glioma.