Size-shrinkable and protein kinase Cα-recognizable nanoparticles for deep tumor penetration and cellular internalization.

In the present study, the three functions, including enhanced permeability and retention (EPR) effect, deep penetration within tumor, and receptor-mediated endocytosis, were integrated into a single platform in order to improve antitumor efficiency. A novel nanoparticle (dendrigraft poly-L-lysine@glycyrrhetinic acid@cyclohexane dicarboxylic anhydride@doxorubicin@ hyaluronic acid composite) has been successfully developed and was denoted as DGL-GA-CDA-DOX-HA. The transmission electron microscope (TEM), dynamic light scattering (DLS), polymer dispersity index (PDI), fourier transform infrared spectrometer (FTIR), and zeta potentials were used to characterize the physicochemical properties of the nanoparticles. According to the results of TEM and DLS, the DGL-GA-CDA-DOX-HA nanoparticles could be rapidly degraded with a size shrink from 182.5 nm to 47.7 nm by hyaluronidase (HAase) added in the medium. The loading amount of DOX reached 252.03 ± 36.38 mg/g for DGL-GA-CDA-DOX nanoparticles. When the nanoparticles were in a medium with HAase at pH 5.0, the drug quickly released. However, when the nanoparticles were exposed to a medium without HAase at pH 5.0, or a neutral medium containing HAase, drug release slowed down. The modification of GA on nanoparticles significantly enhanced their affinity and cytotoxicity to hepatocellular carcinoma HepG2 cells. The study showed that the penetrability of DGL-GA-CDA-DOX and DGL-GA-CDA DOX-HA nanoparticles pre-degraded by HAase in vitro multicellular tumor spheroids were always better than that of DGL-GA-CDA-DOX-HA nanoparticles untreated by HAase. The imaging in vivo and ex vivo exhibited that DGL-GA-CDA-DOX-HA nanoparticles could preferentially accumulate in the tumor site. Correspondingly, the DGL-GA-CDA-DOX-HA displayed the preferable antitumor efficiency to other experimental groups in H22 tumor-bearing mice, with a tumor inhibition rate of 71.6%. In short, these results suggested that DGL-GA-CDA-DOX-HA nanoparticles could promote therapeutic effects by modulating particle size and GA receptor-mediated endocytosis.

pH-Sensitive nanoparticles as smart carriers for selective intracellular drug delivery to tumor.

Herein, a smart pH-sensitive nanoparticle (DGL-PEG-Tat-KK-DMA-DOX) was prepared to achieve the selective intracellular drug delivery. In this nanoparticle, a PEG-grafted cell penetrating peptide (PEG-Tat-KK) was designed and acted as the cell penetrating segment. By introducing the pH-sensitive amide bonds between the peptide and blocking agent (2,3-dimethylmaleic anhydride, DMA), the controllable moiety (PEG-Tat-KK-DMA) endowed the nanoparticle with a charge-switchable shell and temporarily blocked penetrating function, thus improving the specific internalization. Besides, dendrigraft poly-L-lysine (DGL) used as the skeleton can greatly improve the drug loading because of the highly dendritic framework. Under the stimuli of acidic pH, this nanoparticle exhibited a remarkable charge-switchable property. The drug release showed an expected behavior with little release in the neutral pH media but relatively fast release in the acidic media. The in vitro experiments revealed that the cellular uptake and cytotoxicity were significantly enhanced after the pH was decreased. In vivo biodistribution and antitumor research indicated that the nanoparticle had noteworthy specificity and antitumor efficacy with a tumor inhibition rate of 79.7%. These results verified this nanoparticle could efficiently improve the selective intracellular delivery and possessed a great potential in tumor treatment.

Comparison of histologic, biochemical, and mechanical properties of murine skin treated with the 1064-nm and 1320-nm Nd:YAG lasers.

The goal of this study was to compare the effects of the Q-switched 1064-nm Nd:YAG laser and the 1320-nm Nd:YAG laser non-ablative treatments on mouse skin in vivo. Skin elasticity measurements were carried out with a Reviscometer, and skin samples were taken for histological study, hydroxyproline content assay and estimation of collagen type I and III. By the second month after non-ablative treatments, the 1064-nm laser treatment resulted in an average of 25% greater improvement of skin elasticity, 6% more increase of dermal thickness, and 11% higher synthesis of hydroxyproline than the 1320-nm laser. Collagen type III increased markedly after the 1064-nm laser treatment whereas more collagen type I was elicited by the 1320-nm laser. Our results demonstrated that the 1064-nm laser was more effective than the 1320-nm Nd:YAG laser in non-ablative treatments, but the results needed to be confirmed in humans. It appeared that photo-mechanic reaction could cause more collagen type III synthesis whereas the photo-thermal effect was in favor of the formation of collagen type I.