The role of polyethylene glycol size in chemical spectra, cytotoxicity, and release of PEGylated nanoliposomal cisplatin

This study aimed to synthesize methoxy polyethylene glycol propionaldehyde (mPEG20,000-ALD) for the preparation of PEGylated nanoliposomal cisplatin. Nanocarriers such as liposomes are developed for a wide range of drug delivery systems. PEG with high molecular weight (Mw) is used to coat the liposomes. In this study, simulated Fourier transform infrared (FTIR) spectra of mPEG-ALD were obtained using density functional theory (DFT) calculations and then compared with actual FTIR spectrum of mPEG20,000-ALD (Mw = 20 kDa). We found that the intensity of C = O stretching vibration at 1,700 cm−1 related to the carbonyl functional group of mPEG20,000-ALD was very weak. The results of DFT calculations of mPEG-ALD showed that by increasing the Mw of mPEG-ALD, the intensity of C = O stretching vibration related to the carbonyl functional group of mPEG-ALD was decreased, so we concluded the hypothesis of decreasing the intensity of C = O stretching vibration at 1,700 cm−1 as a result of increasing the Mw of mPEG-ALD. In vitro release of cisplatin showed that the percentages of released cisplatin from PEGylated nanoliposomal cisplatin and free cisplatin were determined to be 46 ± 2% and 97 ± 3% after 35 h, respectively. Cytotoxicity of free cisplatin and PEGylated nanoliposomal cisplatin was evaluated and related half-maximal inhibitory concentration on human ovarian cancer cell line A2780CP was obtained to be 76.6 ± 3.1 and 46.6 ± 2.3 μg/mL, respectively.