Preparation of a tumor-targeted drug-loading material, amphiphilic peptide P10, and analysis of its anti-tumor activity

Preparation of an amphiphilic peptide (P13) with proton sponge effect and analysis of its antitumor activity

In order to prevent drugs from being captured and degraded by the acidic environment of organelles, such as lysosomes, after entering cells, this study designed and synthesized a novel carrier amphiphilic polypeptide (DGRHHHLLLAAAA), designated P13, for use as a tumor-targeting drug delivery vehicle. The P13 peptide was synthesized by the solid phase synthesis method, and its self-assembly behavior and drug-loading capacity in aqueous solution were studied and characterizedin vitro. Doxorubicin (DOX) was loaded by dialysis method, and P13 and DOX were mixed at a mass ratio of 6:1 to form regular rounded globules. The acid-base buffering capacity of P13 was investigated determined by acid-base titration. The results revealed that P13 had excellent acid-base buffering capacity, a critical micelle concentration value of about 0.000 21 g l^-1, and the particle size of P13-Dox nanospheres was 167 nm. The drug encapsulation efficiency and drug loading capacity of micelles were 20.40 ± 1.21% and 21.25 ± 2.79%, respectively. At the concentration of 50μg ml^-1of P13-DOX , the inhibition rate was 73.35%. The results of thein vivoantitumor activity assay in mice showed that P13-DOX also exhibited excellent inhibitory effect on tumor growth, compared with the tumor weight of 1.1 g in the control group, the tumor weight in the P13-DOX-treated group was only 0.26 g. Additionally, the results of hematoxylin and eosin staining of the organs showed that P13-DOX had no damaging effect on normal tissues. The novel amphiphilic peptide P13 with proton sponge effect designed and prepared in this study is expected to be a promising tumor-targeting drug carrier with excellent application potential.

De novosynthesis of pH-responsive, self-assembled, and targeted polypeptide nano-micelles for enhanced delivery of doxorubicin

Doxorubicin (DOX) is a commonly used anticancer drug, but it is inefficient as a therapeutic due to a lack of targeting. Peptide-tuned self-assembly of DOX offers a strategy to improve targeting for greater efficacy. In this work, we designed and prepared an amphiphilic tumor cell-targeting peptide, P14 (AAAAFFFHHHGRGD), able to encapsulate DOX by self-assembly to form tumor cell-targeting and pH-sensitive nano-micelles. The results showed a critical P14-micelle concentration of 1.758 mg l^-1and an average particle size of micelles of 121.64 nm, with entrapment and drug-loading efficiencies of 28.02% ± 1.35% and 12.06% ± 0.59%, respectively. The prepared micelles can release 73.52 ± 1.27% DOX within 24 h in pH 4.5 medium, and the drug cumulative release profile of micelles can be described by the first-order model. Compared with free DOX, the micelles exhibited an increased ability to inhibit tumor cell growth and cause tumor apoptosisin vitro, with IC₅₀values of DOX and P14-DOX micelles against human breast cancer cells (MCF-7) of 0.91 ± 0.07 and 0.75 ± 0.06μg ml^-1, respectively, and cellular apoptotic rates of DOX and P14-DOX micelles of 70.3% and 42.4%, respectively. Cellular uptake experiments revealed high concentrations of micelles around and inside MCF-7 cells, demonstrating that micelles can target tumor cells. These results indicate the excellent potential for the application of this amphiphilic peptide as a carrier for small-molecule drugs and suggest a strategy for the design of effective anti-tumor drugs.