Endolysosomal environment-responsive photodynamic nanocarrier to enhance cytosolic drug delivery via photosensitizer-mediated membrane disruption

Photomediated Reactive Oxygen Species-Generable Nanoparticles for Triggered Release and Endo/Lysosomal Escape of Drug upon Attenuated Single Light Irradiation

Nanoparticles with "smart" stimuli-responsive materials and multiple therapeutic strategies in a single delivery platform have emerged for highly efficient cancer therapy. Here, photomediated reactive oxygen species (ROS)-generable nanoparticles are designed that can trigger drug release and endo/lysosomal escape upon attenuated single light irradiation, simultaneously, for synergistic chemo-photodynamic ablation. In this study, the self-ROS-generable nanoparticles (SRNs) are prepared from the polymer based on polysaccharide, chlorin e6 as ROS generator and lipoic acid as ROS scavenger covalently conjugated pullulan with anticancer drug (doxorubicin, DOX) through self-assembly, and can disassemble via the ROS-mediated reduction of lipoyl group in response to low level exogenous single light switch. After cellular internalization in hepatic cancer through asialoglycoprotein receptor (ASGPR, as pullulan receptor)-mediated endocytosis, once irradiated, SRNs are able to produce ROS that can simultaneously induce drug release triggering and endo/lysosomal escape of DOX into cytoplasm as well as directly photodynamic therapy for highly efficient chemo-photodynamic cancer therapy. This promising delivery system, which has huge potential in biomedical applications, may be optimal for smart delivery platform.

Investigation of Fatty Acid Ketohydrazone Modified Liposome's Properties as a Drug Carrier

pH-responsive liposomes were prepared by modifying the liposome with acid-cleaving amphiphiles. Palmitic ketohydrazone (P-KH) or stearic ketohydrazone (S-KH), composed of hydrophilic sugar headgroup and hydrophobic acyl chain, was used as a modifier of the DMPC liposome. Because the ketohydrazone group of P-KH or S-KH was cleaved at low pH conditions (<pH 5.0), the delivery of the P-KH modified liposomes was observed probably via an endocytic pathway. The membrane properties of these liposomes were characterized, focusing on the variation of both polarity (measured by Laurdan) and membrane fluidity (measured by DPH) at low pH condition. The interface of the P-KH modified liposome at acidic pH was found to become more hydrophobic and less fluidic as compared with that at neutral pH; that is, P-KH modified liposome became more rigid structure. Therefore, it seems that the P-KH modified liposome could protect encapsulated drugs from the enzymes in the lysosome. This study shows the novel approach about design of pH-responsive liposomes based on the membrane properties.

Light-Controlled Delivery of Monoclonal Antibodies for Targeted Photoinactivation of Ki-67

The selective inhibition of intracellular and nuclear molecules such as Ki-67 holds great promise for the treatment of cancer and other diseases. However, the choice of the target protein and the intracellular delivery of the functional agent remain crucial challenges. Main hurdles are (a) an effective delivery into cells, (b) endosomal escape of the delivered agents, and (c) an effective, externally triggered destruction of cells. Here we show a light-controlled two-step approach for selective cellular delivery and cell elimination of proliferating cells. Three different cell-penetrating nano constructs, including liposomes, conjugates with the nuclear localization sequence (NLS), and conjugates with the cell penetrating peptide Pep-1, delivered the light activatable antibody conjugate TuBB-9-FITC, which targets the proliferation associated protein Ki-67. HeLa cells were treated with the photosensitizer benzoporphyrin monoacid derivative (BPD) and the antibody constructs. In the first optically controlled step, activation of BPD at 690 nm triggered a controlled endosomal escape of the TuBB-9-FITC constructs. In more than 75% of Ki-67 positive, irradiated cells TuBB-9-FITC antibodies relocated within 24 h from cytoplasmic organelles to the cell nucleus and bound to Ki-67. After a second light irradiation at 490 nm, which activated FITC, cell viability decreased to approximately 13%. Our study shows an effective targeting strategy, which uses light-controlled endosomal escape and the light inactivation of Ki-67 for cell elimination. The fact that liposomal or peptide-assisted delivery give similar results leads to the additional conclusion that an effective mechanism for endosomal escape leaves greater variability for the choice of the delivery agent.

Photochemical tissue penetration via photosensitizer for effective drug penetration in a non-vascular tumor

To improve the tissue penetration efficiency (PE%) of hydrophilic-drugs in non-vascular drug eluting stents (DES), we designed photochemical tissue penetration (PTP) invested DES (PTP-DES). The PTP technology was applied to the stent as a covering membrane to generate singlet oxygen. Singlet oxygen damages the epithelial layer, so the PE% of released drugs could be improved. To prepare the PTP-DES membrane, chlorin e6 (Ce6, photosensitizer) was incorporated in a gemcitabine (GEM) eluting polyurethane (PU) membrane (Ce6-GEM-PU). Ce6-GEM-PU has smooth surface that is ∼40 μm thick. The photoactivity of Ce6 was maintained for 2 weeks (in vitro GEM releasing period). In a separate cell culture system, both 1.5 folds higher PE% and an improved tumor cell growth inhibition effect were shown after light exposure. Additionally, in tissue penetration experimental system, 2 folds increased in the PE% of GEM was induced by laser exposure at 80 J/cm2. Additionally, improved PE% of hydrophilic molecules (Fluorescein and GEM) was confirmed in colon tumor bearing mice. Consequentially, tumor growth, when implanted with Ce6-GEM-PU, was effectively inhibited without significant side effects. Based on these results, we believe that the PTP-DES system has great potential for improving the therapeutic effect of conventional DES.

Advances in the synthesis and application of nanoparticles for drug delivery

The continuous development of drug delivery systems (DDSs) has been extensively researched by the need to maximize therapeutic efficacy while minimizing undesirable side effects. Nanoparticle technology was recently shown to hold great promise for drug delivery applications in nanomedicine due to its beneficial properties, such as better encapsulation, bioavailability, control release, and lower toxic effect. Despite the great progress in nanomedicine, there remain many limitations for clinical application. To overcome these limitations, advanced nanoparticles for drug delivery have been developed to enable the spatially and temporally controlled release of drugs in response to specific stimuli at disease sites. Furthermore, the controlled self-assembly of organic and inorganic materials may enable their use in theranostic applications. This review presents an overview of a recent advanced nanoparticulate system that can be used as a potential drug delivery carrier and focuses on the potential applications of nanoparticles in various biomedical fields for human health care.

Photodynamic tumor therapy of nanoparticles with chlorin e6 sown in poly(ethylene glycol) forester

We developed novel photosensitizing drug-carrying nanoparticles with poly(ethylene glycol) (PEG) forester.

Aptamer-functionalized gold nanoparticles as photoresponsive nanoplatform for co-drug delivery

Various platforms have been developed as innovative nanocarriers to deliver therapeutic agents to the diseased sites. Multifunctional surface modification allows an enhanced recognition and uptake of drug carriers by targeted cells. However, the development of drug resistance in some tumor cells plays a major role in the failure of chemotherapy. Drugs given in combination, called multidrug delivery approach, was designed to improve the therapeutic efficacy and has become an increasingly used strategy that is of great importance in clinical cancer treatments. In this study, aptamer-functionalized gold nanoparticles (Au NPs) have been used as a nanoplatform to codeliver two different anticancer drugs for improving the drug effectiveness. The surface of Au NPs (13 nm in diameter) was assembled with AS1411 aptamers, which tethered with 21-base pairs of (CGATCGA)3 sequence approached to the Au NPs. Both the photosensitizer 5,10,15,20-tetrakis(1-methylpyridinium-4-yl) porphyrin (TMPyP4) and the chemotherapeutic drug doxorubicin (Dox) were then physically attached to the AS1411-conjugated Au NPs (T/D:ds-NPs) and delivered to the target tumor cells such as HeLa and Dox-resistant MCF-7R cell lines. When exposed to a 632 nm light, reactive oxygen species induced by TMPyP4 molecules were generated inside the living cells, followed by cell damage. In addition, triggered release of the complementary drugs also occurred simultaneously during the photodynamic reaction. In the presence of Dox molecules, the toxicity toward the target cells was superior to individual drug treatment. Overall, a co-drug delivery platform was successfully established to improve the therapeutic efficacy in tumor cells. The improvement of the photodynamic-stimulated triggered release was enhanced, thus highly promising precise drug release in targeted drug delivery.

A cancer-recognizing polymeric photosensitizer based on the tumor extracellular pH response of conjugated polymers for targeted cancer photodynamic therapy

Herein, a cancer-recognizing polymeric photosensitizer (CRPP) was demonstrated not only for high water solubility but also for pH-responsive targeted photodynamic cancer therapy. The synthesized CRPP exhibited high water solubility and the pH-dependent charge-switching property. From an in vitro cellular internalization study with HCT-116 human colon cancer cells, significantly enhanced cellular uptake as detected for CRPP at pH 6.5 compared to the cellular uptake of CRPP at pH 7.4, which led to enhanced cytotoxicity in the cancer cells. Finally, the CRPP was found to exhibit high tumor-targeting efficacy in an in vivo tumor model and was finally excreted through the renal route.

Biomimetic nanoparticles for siRNA delivery in the treatment of leukaemia

Leukaemia is a bone marrow cancer occurring in acute and chronic subtypes. Acute leukaemia is a rapidly fatal cancer potentially causing death within a few weeks, if untreated. Leukaemia arises as a result of disruption to haematopoietic precursors, caused either by acquired gene fusions, gene mutations or inappropriate expression of the relevant oncogenes. Current treatment options have made significant progress, but the 5 year survival for acute leukaemia remains under 10% in elderly patients, and less than 50% for some types of acute leukaemia in younger adults. For chronic leukaemias longer survival is generally expected and for chronic myeloid leukaemia patients on tyrosine kinase inhibitors the median survival is not yet reached and is expected to exceed 10 years. Chemotherapy and haematopoietic stem cell transplantation (HSCT) for acute leukaemia provide the mainstay of therapy for patients under 65 and both carry significant morbidity and mortality. Alternative and superior therapeutic strategies for acute leukaemias are urgently required. Recent molecular-based knowledge of recurring chromosome rearrangements, in particular translocations and inversions, has resulted in significant advances in understanding the molecular pathogenesis of leukaemia. Identification of a number of unique fusion genes has facilitated the development of highly specific small interfering RNAs (siRNA). Although delivery of siRNA using multifunctional nanoparticles has been investigated to treat solid cancers, the application of this approach to blood cancers is at an early stage. This review describes current treatments for leukaemia and highlights the potential of leukaemic fusion genes as therapeutic targets for RNA interference (RNAi). In addition, the design of biomimetic nanoparticles which are capable of responding to the physiological environment of leukaemia and their potential to advance RNAi therapeutics to the clinic will be critically evaluated.

pH-sensitive nanoformulated triptolide as a targeted therapeutic strategy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has one of the worst prognoses for survival as it is poorly responsive to both conventional chemotherapy and mechanism-directed therapy. This results from a lack of therapeutic concentration in the tumor tissue coupled with the highly toxic off-site effects exhibited by these compounds. Consequently, we believe the best packaging for holistic therapy for HCC will involve three components: a potent therapeutic, a rationally designed drug delivery vehicle to enrich the target site concentration of the drug, and a surface ligand that can enable a greater propensity to internalization by tumor cells compared to the parenchyma. We screened a library containing hundreds of compounds against a panel of HCC cells and found the natural product, triptolide, to be more effective than sorafenib, doxorubicin, and daunorubicin, which are the current standards of therapy. However, the potential clinical application of triptolide is limited due to its poor solubility and high toxicity. Consequently, we synthesized tumor pH-sensitive nanoformulated triptolide coated with folate for use in an HCC-subpopulation that overexpresses the folate receptor. Our results show triptolide itself can prevent disease progression, but at the cost of significant toxicity. Conversely, our pH-sensitive nanoformulated triptolide facilitates uptake into the tumor, and specifically tumor cells, leading to a further increase in efficacy while mitigating systemic toxicity.

A charge-switchable, four-armed polymeric photosensitizer for photodynamic cancer therapy

A water-soluble, charge-switchable, four-armed polymeric photosensitizer (C4P-PS), in which charge switching is pH dependent, has been designed as a new class of photosensitizer for photodynamic cancer therapy.