An anthraquinone-enzyme-peptide hybrid as a photo-switchable enzyme.

A purpose-designed anthraquinone-horseradish peroxidase (HRP)-cell penetrating peptide hybrid 1 showed high and effective cell permeability. Furthermore, 1 exhibited enzymatic activity without photo-irradiation, whereas significant self-degradation and loss of enzymatic activity occurred upon photo-irradiation in living cells.

Photoswitching of Cell Penetration of Amphipathic Peptides by Control of α-Helical Conformation.

We stapled an amphipathic peptide mainly consisting of leucine (L) and lysine (K) by an azobenzene (Ab) linker for photocontrol of the secondary structure. The cis- trans isomerization of the Ab moieties could stabilize and destabilize the α-helical conformation of the LK peptide along with dramatic change of associated peptide structures in a reversible manner by UV-vis irradiation. The cell-penetrating activities of the LK peptide can be readily regulated by the photocontrol, as the stabilized cis-Ab-LK peptide showed remarkable increase of cell penetration compared to the destabilized trans-Ab-LK peptide. The photoswitchable cell-penetrating peptides would provide important structural information for cell permeability as well as an effective targeting strategy for peptide-based pharmaceuticals with spatiotemporal specificity.

Dual-Targeted Selenium Nanoparticles for Synergistic Photothermal Therapy and Chemotherapy of Tumors.

A combination of chemo- and photothermal therapy has emerged as a promising tactic for cancer therapy. However, the intricacy of accurate delivery and the ability to initiate drug release in specific tumor sites remains a challenging puzzle. Hence, to assure that the chemotherapeutic drug and photothermal agent are synchronously delivered to a tumor area for their synergistic effect, dual-target (RC-12 and PG-6 peptides) functionalized selenium nanoparticles loaded with both doxorubicin (DOX) and indocyanine green (ICG) were designed and successfully synthesized. The as-synthesized nanoparticles exhibited good monodispersity, size stability, and consistent spectral characteristics compared with those of ICG or DOX alone. The nanoparticles underwent self-immolated cleavage under irradiation from a near-IR laser and released the loaded drug owing to sufficient hyperthermia. Moreover, the internalized nanoparticles triggered the overproduction of intracellular reactive oxygen species to induce cell apoptosis. Taken together, this study provides a sequentially triggered nanosystem to achieve precise drug delivery by chemo-photothermal combination.

Affinity-Based Assembly of Peptides on Plasmonic Nanoparticles Delivered Intracellularly with Light Activated Control.

We report a universal strategy for functionalizing near-infrared light-responsive nanocarriers with both a peptide "cargo" and an orthogonal cell-penetrating peptide. Modularity of both the cargo and the internalization peptide attachment is an important feature of these materials relying on the robust affinity of polyhistidine tags to nitrilotriacetic acid in the presence of nickel as well as the affinity of biotin labeled peptides to streptavidin. Attachment to the gold surface uses thiol-labeled scaffolds terminated with the affinity partner. These materials allow for unprecedented spatiotemporal control over the release of the toxic α-helical amphipathic peptide (KLAKLAK)2 which disrupts mitochondrial membranes and initiates apoptotic cell death. Laser treatment at benign near-infrared wavelengths releases peptide from the gold surface as well as breaches the endosome barrier for cytosolic activity (with 105-fold improved response to peptide activity over the free peptide) and can be monitored in real time.

Photo-responsive and NGR-mediated multifunctional nanostructured lipid carrier for tumor-specific therapy.

A novel nanostructured lipid carrier (NLC) modified with photon-sensitive cell penetrating peptides (psCPP) and Asn-Gly-Arg (NGR) was designed to enhance paclitaxel (PTX)-targeted delivery and antitumor effect. The NGR moiety selectively binds to CD13-positive tumors. On other hand, the psCPP moiety enhance specific cancer cellular uptake after rapidly cleaving the two-photon excitation-responsive protective group, in this case, illumination in the presence of near-IR (NIR) light at the tumor site. The dual-modified NLC (psCPP/NGR-NLC) were prepared by emulsification method, and the concentrations of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-polyethylene glycol 2000-psCPP (DSPE-PEG2000 -psCPP) and DSPE-PEG5000 -NGR in the NLC were chosen to be 4% and 1% (molar ratio), respectively. The mean particle size of the psCPP/NGR-NLC was about 100 nm, and the drug entrapment efficiency was more than 90%. Stability study showed that the prepared NLCs were physically and chemically stable at 2°C-8°C up to 1 month. Cellular uptake results demonstrated that the proposed psCPP/NGR-NLC had an enhancement of cancer cell recognition and specific uptake. Pharmacokinetic study showed that the prepared psCPP/NGR-NLC possessed the long-circulation characteristic with the t1/2 of 6.112 ± 0.304 h. Pharmacodynamics results confirmed that, with the aid of NIR illumination and NGR, the tumor inhibition ratio of psCPP/NGR-NLC group was significantly higher than the other PTX groups.

Constrained and UV-activatable cell-penetrating peptides for intracellular delivery of liposomes.

Herein we report on the development of a novel method of constraining a cell-penetrating peptide, which can be used to trigger transport of liposomes into cells upon in this case radiation with UV-light. A cell-penetrating peptide, which was modified on both termini with an alkyl chain, was anchored to the liposomal surface in a constrained and deactivated form. Since one of the two alkyl chains was connected to the peptide via a UV-cleavable linker, disconnection of this alkyl chain upon irradiation led to the exposure of the cell-penetrating peptide, and mediated the transport of the entire liposome particle into cells.