The emergence of liposomes has provided a breakthrough for the clinical use of highly toxic chemotherapeutic drugs . However, the clinical effects of conventional drug-loaded liposomes are unsatisfactory due to the lack of specific targeting of cancer cells and the inability to achieve endosome escape and controllable release in vivo. In this paper, a cRGD-PEOz-Hz-DOB (cPzD) molecule with specific targeting, endosomal escape, and endogenous acid-sensitive controlled release ability was creatively designed and synthesized to prepare drug-loaded liposomes cPzDGX encapsulating the anticancer drug Doxorubicin (DOX) in order to enhance the anticancer performance of DOX. The study found that the hydrazone bond in cPzD reached a breakage rate of 42% within 48 h at pH 5.0, so the cumulative release rate of cPzDGX at pH 5.0 for 48 h was as high as 82.9%, which was 22.5% higher than that at pH 7.4. Moreover, the uptake of cPzDGX in A549/ADR cells was increased by 62% at 2 h, and the expression of the green fluorescent protein gene EGFP was also increased by 36% relative to the targeting control group, indicating that cRGD modification could effectively improve the targeting ability of liposomes to cancer cells. In addition, it was demonstrated that PEOz modification could help drug carriers achieve endosome escape because the green fluorescent protein expression in the PEOz-modified liposome group was 60.5% higher than that in the PEG-modified group. Finally, the cell viability of the cPzDGX group decreased by 17.2% relative to the free DOX group when the DOX concentration was 1 μg/mL in the cytotoxicity assay, and the diameter reduction of 3D tumor MCs increased by 34.4%. And cPzDGX could effectively enhance the permeability of free DOX to solid tumors. The above results indicate that the DOX-loaded liposomes cPzDGX we designed have great prospects for the accurate and efficient treatment of cancer.
The structural change of receptor protein at high temperatures is one of the factors affecting the targeting ability of ligand-installed nanocarriers for combined therapy of hyperthermia and drug delivery. In this study, the binding behaviors and mechanisms of integrin αvβ3 receptor and the arginine-glycine-aspartic acid (RGD) peptide ligand at high temperatures were investigated both theoretically and experimentally. The structural parameters of integrin αvβ3 at different temperatures and the interaction forces between the RGD peptide and integrin αvβ3 at different binding sites were calculated by molecular dynamics simulation. Fourier transform infrared spectroscopy, energy dispersive spectroscopy, ultraviolet–visible absorption spectroscopy, and atomic force microscopy were used to analyze the structural changes of integrin αvβ3 and to measure the ligand-receptor interaction. Results show that the number of hydrogen bonds decreased and the secondary structure of integrin αvβ3 changed with the increase in temperature, indicating the denaturation of integrin αvβ3. The structural stability of the integrin αv subunit was better than that of the integrin β3 subunit at high temperatures. The interaction between the RGD peptide and integrin αvβ3 weakened as the temperature increased because the structure of the integrin αvβ3 binding site became more flexible and the corresponding calcium ions were shed from the binding site. The strongest interaction force was exhibited at the binding site of the integrin β3 subunit at 310 K while it was found at the binding site of the integrin αv subunit at higher temperatures, owing to the smaller structure deformation of the integrin αv subunit. Graphical
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