Rational design of ROS-responsive nanocarriers for targeted X-ray-induced photodynamic therapy and cascaded chemotherapy of intracranial glioblastoma

Glioblastoma (GBM) is the most lethal primary intracranial tumor because of its high invasiveness and recurrence. Therefore, nanocarriers with blood-brain barrier (BBB) penetration and transcranial-controlled drug release and activation are rather attractive options for glioblastoma treatment. Herein, we designed a multifunctional nanocarrier (T-^TKNP_VP) that combined targeted X-ray-induced photodynamic therapy (X-PDT) and cascaded reactive oxygen species (ROS)-boosted chemotherapy. The T-^TKNP_VP loaded with verteporfin (VP) and paclitaxel (PTX) was self-assembled from an angiopep-2 (Ang) peptide, functionalized Ang-PEG-DSPE and ROS-sensitive PEG-TK-PTX conjugate. After systemic injection, the T-^TKNP_VP efficiently crossed the BBB and targeted the GBM cells via receptor-mediated transcytosis. Upon X-ray irradiation, they can generate a certain amount of ROS, which not only induces X-PDT but also locoregionally activates PTX release and action by cleaving the TK bridged bonds. As evidenced by 9.4 T MRI and other experiments, such nanocarriers offer significant growth inhibition of GBM in situ and prolong the survival times of U87-MG tumor-bearing mice. Taken together, the designed T-^TKNP_VP provided an alternative avenue for realizing transcranial X-PDT and X-ray-activated chemotherapy for targeted and locoregional GBM treatment in vivo.

Mitochondria targeting molecular transporters: synthesis, lipophilic effect, and ionic complex

As mitochondria are potential therapeutic targeting sites for the treatment of human diseases, delivering cytotoxic drugs, antioxidants, and imaging molecules to mitochondria can provide new therapeutic opportunities. In an attempt to develop a new mitochondria-targeting vector, we synthesized sorbitol-based molecular transporters with multiple guanidines, measured their partition coefficients, compared their targeting efficiency using fluorescent images and Pearson's correlation coefficients, and studied cellular uptake mechanisms. To increase the targeting ability of these molecular transporters to mitochondria, alanine-naphthalene as a lipophilic group was attached to the molecular transporter, which improved translocation across cellular membranes and led to higher accumulation in mitochondria. The molecular transporter was able to form an ionic complex with antibiotics, resulting in low cell viability. These data demonstrate that the molecular transporter with a lipophilic group could be utilized as a potential drug delivery vector for treating mitochondrial dysfunction.

Effects of processing parameters on the properties of amphiphilic block copolymer micelles prepared by supercritical carbon dioxide evaporation method

The operation parameters for the supercritical carbon dioxide (ScCO2) evaporation method greatly affect the properties of the prepared drug-loaded micelles. In this study, the effects of those key parameters on the drug-loading content (LC) and drug entrapment efficiency (EE) are discussed. It is observed that EE and LC of the micelles are slightly increased with the enhancing temperature and the copolymer molecular ratio of hydrophilic/hydrophobic segment, while decreased with the enhancing ScCO2 evaporation rate. The pressure and volume ratio of ScCO2 to H2O are observed the optimum condition. In addition, the verification experiment is carried out under the obtained optimizing parameters. The prepared micelles exhibit relatively regular spherical shape and narrow size distribution with the EE and LC value of 70.7% and 14.1%, respectively.

A guanidine-appended scyllo-inositol derivative AAD-66 enhances brain delivery and ameliorates Alzheimer's phenotypes

Alzheimer's disease (AD) is a degenerative brain disease that destroys memory and other important mental functions but lacks efficient therapeutic agents. Blocking toxic amyloid β (Aβ) could be beneficial for AD and represents a promising therapeutic strategy for AD treatment. scyllo-Inositol (SI) is a potential therapeutic for AD by directly interacting with the Aβ peptide to inhibit Aβ42 fiber formation. Clinical studies of SI showed promising benefits on mild to moderate AD, however, with limitations on dosage regime. A new strategy to enhance the brain delivery of SI is needed to achieve the efficacy with minimum adverse effects. Herein, we report that a novel guanidine-appended SI derivative AAD-66 resulted in more effective reductions of brain Aβ and plaque deposits, gliosis, and behavioral memory deficits in the disease-established 5xFAD mice. Overall, our present study reveals the potential of AAD-66 as a promising therapeutic agent for AD.

Delivery of paclitaxel using PEGylated graphene oxide as a nanocarrier

Paclitaxel (PTX) is an extensively used potent chemotherapy drug; however, low water solubility, poor bioavailability, and emergence of drug resistance in patients limited its biological application. In this report, we proposed a new drug delivery system for cancer therapy based on graphene oxide (GO), a novel 2D nanomaterial obtained from the oxidation of natural graphite, to improve the utilization rate of PTX. PTX was first connected to biocompatible 6-armed poly(ethylene glycol), followed by covalent introduction into the surface of GO sheets via a facile amidation process under mild conditions, affording the drug delivery system, GO-PEG-PTX (size 50-200 nm). GO-PEG nanosized carrier could quickly enter into human lung cancer A549 and human breast cancer MCF-7 cells verified by inverted fluorescence microscope using fluorescein isothiocyanate as probe. This nanocarrier was nontoxic to A549 and MCF-7 cells without linking with PTX. Nevertheless, GO-PEG-PTX showed remarkably high cytotoxicity to A549 and MCF-7 cells in a broad range of concentration of PTX and time compared to free PTX. This kind of nanoscale drug delivery system based on PEGylated GO may find widespread application in biomedicine.

Injectable small molecule hydrogel as a potential nanocarrier for localized and sustained in vivo delivery of doxorubicin

The majority of the localized drug delivery systems are based on polymeric or polypeptide scaffolds, as weak intermolecular interactions of low molecular weight hydrogelators (LMHGs, Mw <500 Da) are significantly perturbed in the presence of anticancer drugs. Here, we present l-alanine derived low molecular weight hydrogelators (LMHGs) that remain injectable even after entrapping the anticancer drug doxorubicin (DOX). These DOX containing nanoassemblies (DOX-Gel) showed promising anticancer activity in mice models. Subcutaneous injection of DOX-Gel near the tumor achieved a greater decrease in tumour load than by intravenous injection of DOX (DOX-IV), and local injection of DOX alone (DOX-Local) at the tumor site. We noticed that DOX-Gel nanocarriers are especially effective when injected during the early stage of tumor progression, and achieve a substantial decrease in tumor load in the long term.

Covalent functionalization of graphene oxide with biocompatible poly(ethylene glycol) for delivery of paclitaxel

Graphene oxide (GO), a novel 2D nanomaterial prepared by the oxidation of natural graphite, has been paid much attention in the area of drug delivery due to good biocompatibility and low toxicity. In the present work, 6-armed poly(ethylene glycol) was covalently introduced into the surface of GO sheets via a facile amidation process under mild conditions, making the modified GO, GO-PEG (PEG: 65 wt %, size: 50-200 nm), stable and biocompatible in physiological solution. This nanosized GO-PEG was found to be nontoxic to human lung cancer A549 and human breast cancer MCF-7 cells via cell viability assay. Furthermore, paclitaxel (PTX), a widely used cancer chemotherapy drug, was conjugated onto GO-PEG via π-π stacking and hydrophobic interactions to afford a nanocomplex of GO-PEG/PTX with a relatively high loading capacity for PTX (11.2 wt %). This complex could quickly enter into A549 and MCF-7 cells evidenced by inverted fluorescence microscopy using Fluorescein isothiocyanate as a probe, and it also showed remarkably high cytotoxicity to A549 and MCF-7 cells in a broad range of concentration of PTX and time compared to free PTX. This kind of nanoscale drug delivery system on the basis of PEGylated GO may find potential application in biomedicine.

On guanidinium and cellular uptake

Guanidinium-rich scaffolds facilitate cellular translocation and delivery of bioactive cargos through biological barriers. Although impressive uptake has been demonstrated for nonoligomeric and nonpept(o)idic guanidinylated scaffolds in cell cultures and animal models, the fundamental understanding of these processes is lacking. Charge pairing and hydrogen bonding with cell surface counterparts have been proposed, but their exact role remains putative. The impact of the number and spatial relationships of the guanidinium groups on delivery and organelle/organ localization is yet to be established.

Natural products as a rich source of tau-targeting drugs for Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder and the most common form of dementia, affecting more than 5.4 million people in the USA. Although the cause of AD is not well understood, the cholinergic, amyloid and tau hypotheses were proposed to explain its development. Drug discovery for AD based on the cholinergic and amyloid theories have not been effective. In this article we summarize tau-based natural products as AD therapeutics from a variety of biological sources, including the anti-amyloid agent curcumin, isolated from turmeric, the microtubule stabilizer paclitaxel, from the Pacific Yew Taxus brevifolia, and the Streptomyces-derived Hsp90 inhibitor, geldanamycin. The overlooked approach of clearing tau aggregation will most likely be the next objective for AD drug discovery.