Biological Characteristics and Carrier Functions of Pegylated Manganese Zinc Ferrite Nanoparticles

Figure 6

Binding, digestion, and release of PEG-MZF-NPs with CD44-shRNA. (a) Electrophoretograms of PEG-MZF-NPs with various mass ratios after binding with CD44-shRNA plasmids. Lane 1—0 : 1 (100 ng plasmid DNA, with no PEG-MZF-NPs); Lane 2—5 : 1; Lane 3—10 : 1; Lane 4—20 : 1; Lane 5—40 : 1; Lane 6—80 : 1. The electrophoresis images of binding, release, and digestion protection experiments suggested that when plasmid was added at the ratios of 0 : 1, 5 : 1, 10 : 1, 20 : 1, and 40 : 1, clear bands could be seen in lanes. When the mass ratio of magnetic NPs to CD44-shRNA was 40 : 1, the former could practically bind with all plasmids in the system indicating 40 : 1 was an optimal binding ratio. (b) Electrophoretograms of the release experiment of PEG-MZF-NP-CD44-shRNA plasmid complex. Lane 1: 100 ng original plasmid DNA; Lane 2: 1 h; Lane 3: 4 h; Lane 4: 8 h; Lane 5: 12 h; Lane 6: 24 h; Lane 7: 48 h; Lane 8: 72 h; Lane 8: 96 h. Within 1, 4, 8, 12, and 24 h and 2 days, DNA was released at a large amount, but in between day 3 and day 4 it was not greatly different and PEG-MZF-NPs could protect plasmid and effectively release DNA. (c) Digestion protection experiment of PEG-MZF-NPs-CD44-shRNA plasmid complex. Lane 1: 100 ng original plasmid DNA; Lane 2: complex for 1 min; Lane 3: complex for 10 min; Lane 4: complex for 30 min; Lane 5: complex for 45 min; Lane 6: complex for 1 h. In the stability research, the DNase-I digestion experiment was used to observe stability of magnetic nanomaterial/gene complex. The band lightness of PEG-MZF-NP/CD44-shRNA complex in electrophoresis image showed no obvious changes within the first 60 min demonstrating its stability. The exposed CD44-shRNA plasmids were almost digested by DNase-I within 1 min suggesting a good stability of complex, and PEG-MZF-NPs could protect CD44-shRNA from nuclease digestion (Figure 6(c)).

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