Exploration of long-acting implant formulations of hepatitis B drug entecavir.

Alternative formulations of entecavir, a once daily oral hepatitis B antiretroviral, may improve treatment adherence by patients. We explored the use of biocompatible polymers to control entecavir dissolution in two formats suitable for subcutaneous implantation. Hot melt extrudates were prepared by extruding entecavir-polymer blends at specified weight ratios. Dip-coated tablets were prepared by compressing entecavir in a multi-tip tooling. Tablets were dip-coated in solutions of polymer and dried. In rodents, entecavir-poly(caprolactone) extrudates demonstrated >180 days of continuous drug release, although below the estimated efficacious target input rate. Drug pharmacokinetic profiles were tunable by varying the polymer employed and implant format. The rank order trends of drug input rates observed in vitro were observed in vivo in the detected plasma concentrations of entecavir. In all dose groups entecavir was not tolerated locally at the site of administration where adverse event severity correlated with drug input rate. These polymer-based implantable formats have applicability to long-acting formulations of high solubility compounds beyond entecavir.

Extended-Duration MK-8591-Eluting Implant as a Candidate for HIV Treatment and Prevention.

Regimen adherence remains a major hurdle to the success of daily oral drug regimens for the treatment and prevention of human immunodeficiency virus (HIV) infection. Long-acting drug formulations requiring less-frequent dosing offer an opportunity to improve adherence and allow for more forgiving options with regard to missed doses. The administration of long-acting formulations in a clinical setting enables health care providers to directly track adherence. MK-8591 (4'-ethynyl-2-fluoro-2'-deoxyadenosine [EFdA]) is an investigational nucleoside reverse transcriptase translocation inhibitor (NRTTI) drug candidate under investigation as part of a regimen for HIV treatment, with potential utility as a single agent for preexposure prophylaxis (PrEP). The active triphosphate of MK-8591 (MK-8591-TP) exhibits protracted intracellular persistence and, together with the potency of MK-8591, supports its consideration for extended-duration dosing. Toward this end, drug-eluting implant devices were designed to provide prolonged MK-8591 release in vitro and in vivo Implants, administered subcutaneously, were studied in rodents and nonhuman primates to establish MK-8591 pharmacokinetics and intracellular levels of MK-8591-TP. These data were evaluated against pharmacokinetic and pharmacodynamic models, as well as data generated in phase 1a (Ph1a) and Ph1b clinical studies with once-weekly oral administration of MK-8591. After a single administration in animals, MK-8591 implants achieved clinically relevant drug exposures and sustained drug release, with plasma levels maintained for greater than 6 months that correspond to efficacious MK-8591-TP levels, resulting in a 1.6-log reduction in viral load. Additional studies of MK-8591 implants for HIV treatment and prevention are warranted.

Mixed Reality Meets Pharmaceutical Development.

As science evolves, the need for more efficient and innovative knowledge transfer capabilities becomes evident. Advances in drug discovery and delivery sciences have directly impacted the pharmaceutical industry, though the added complexities have not shortened the development process. These added complexities also make it difficult for scientists to rapidly and effectively transfer knowledge to offset the lengthened drug development timelines. While webcams, camera phones, and iPads have been explored as potential new methods of real-time information sharing, the non-"hands-free" nature and lack of viewer and observer point-of-view render them unsuitable for the R&D laboratory or manufacturing setting. As an alternative solution, the Microsoft HoloLens mixed-reality headset was evaluated as a more efficient, hands-free method of knowledge transfer and information sharing. After completing a traditional method transfer between 3 R&D sites (Rahway, NJ; West Point, PA and Schnachen, Switzerland), a retrospective analysis of efficiency gain was performed through the comparison of a mock method transfer between NJ and PA sites using the HoloLens. The results demonstrated a minimum 10-fold gain in efficiency, weighing in from a savings in time, cost, and the ability to have real-time data analysis and discussion. In addition, other use cases were evaluated involving vendor and contract research/manufacturing organizations.

Efficacy, long-term toxicity, and mechanistic studies of gold nanorods photothermal therapy of cancer in xenograft mice.

Gold nanorods (AuNRs)-assisted plasmonic photothermal therapy (AuNRs-PPTT) is a promising strategy for combating cancer in which AuNRs absorb near-infrared light and convert it into heat, causing cell death mainly by apoptosis and/or necrosis. Developing a valid PPTT that induces cancer cell apoptosis and avoids necrosis in vivo and exploring its molecular mechanism of action is of great importance. Furthermore, assessment of the long-term fate of the AuNRs after treatment is critical for clinical use. We first optimized the size, surface modification [rifampicin (RF) conjugation], and concentration (2.5 nM) of AuNRs and the PPTT laser power (2 W/cm2) to achieve maximal induction of apoptosis. Second, we studied the potential mechanism of action of AuNRs-PPTT using quantitative proteomic analysis in mouse tumor tissues. Several death pathways were identified, mainly involving apoptosis and cell death by releasing neutrophil extracellular traps (NETs) (NETosis), which were more obvious upon PPTT using RF-conjugated AuNRs (AuNRs@RF) than with polyethylene glycol thiol-conjugated AuNRs. Cytochrome c and p53-related apoptosis mechanisms were identified as contributing to the enhanced effect of PPTT with AuNRs@RF. Furthermore, Pin1 and IL18-related signaling contributed to the observed perturbation of the NETosis pathway by PPTT with AuNRs@RF. Third, we report a 15-month toxicity study that showed no long-term toxicity of AuNRs in vivo. Together, these data demonstrate that our AuNRs-PPTT platform is effective and safe for cancer therapy in mouse models. These findings provide a strong framework for the translation of PPTT to the clinic.

In vitro investigations of gold nanocages: Toxicological profile in human keratinocyte cell line.

Gold nanocages (AuNCs) are comparatively novel nanostructures, as many of their characteristics are still to be exploited. The purpose of present study was to systematically investigate the toxicological effects of AuNCs on human keratinocyte cell line (HaCaT) utilizing Dark Field (DF)/Bright Field (BF) imaging and flow cytometry cell cycle techniques. We have applied surface modification, concentration, and incubation time of AuNCs as variables to investigate their effect on the cellular imaging and cell cycle response of HaCaT cells. The results indicate that the AuNCs interact with HaCaT cells in accordance to their surface charge and concentration. Cellular uptake is evident from DF images which lead to the cell cycle perturbations and apoptosis in HaCaT cells. AuNCs cause a prominent G2/M phase arrest after 24 h of incubation. To the best of our knowledge toxicological effects of AuNCs on cell cycle of HaCaT cell line in vitro are not reported previously.

Biological Targeting of Plasmonic Nanoparticles Improves Cellular Imaging via the Enhanced Scattering in the Aggregates Formed.

Gold nanoparticles (AuNPs) demonstrate great promise in biomedical applications due to their plasmonically enhanced imaging properties. When in close proximity, AuNPs plasmonic fields couple together, increasing their scattering cross-section due to the formation of hot spots, improving their imaging utility. In the present study, we modified the AuNPs surface with different peptides to target the nucleus and/or the cell as a whole, resulting in similar cellular uptake but different scattering intensities. Nuclear-targeted AuNPs showed the greatest scattering due to the formation of denser nanoparticle clusters (i.e., increased localization). We also obtained a dynamic profile of AuNP localization in living cells, indicating that nuclear localization is directly related to the number of nuclear-targeting peptides on the AuNP surface. Increased localization led to increased plasmonic field coupling, resulting in significantly higher scattering intensity. Thus, biochemical targeting of plasmonic nanoparticles to subcellular components is expected to lead to more resolved imaging of cellular processes.

The optical, photothermal, and facile surface chemical properties of gold and silver nanoparticles in biodiagnostics, therapy, and drug delivery.

Nanotechnology is a rapidly growing area of research in part due to its integration into many biomedical applications. Within nanotechnology, gold and silver nanostructures are some of the most heavily utilized nanomaterial due to their unique optical, photothermal, and facile surface chemical properties. In this review, common colloid synthesis methods and biofunctionalization strategies of gold and silver nanostructures are highlighted. Their unique properties are also discussed in terms of their use in biodiagnostic, imaging, therapeutic, and drug delivery applications. Furthermore, relevant clinical applications utilizing gold and silver nanostructures are also presented. We also provide a table with reviews covering related topics.

The most effective gold nanorod size for plasmonic photothermal therapy: theory and in vitro experiments.

The development of new and improved photothermal contrast agents for the successful treatment of cancer (or other diseases) via plasmonic photothermal therapy (PPTT) is a crucial part of the application of nanotechnology in medicine. Gold nanorods (AuNRs) have been found to be the most effective photothermal contrast agents, both in vitro and in vivo. Therefore, determining the optimum AuNR size needed for applications in PPTT is of great interest. In the present work, we utilized theoretical calculations as well as experimental techniques in vitro to determine this optimum AuNR size by comparing plasmonic properties and the efficacy as photothermal contrast agents of three different sizes of AuNRs. Our theoretical calculations showed that the contribution of absorbance to the total extinction, the electric field, and the distance at which this field extends away from the nanoparticle surface all govern the effectiveness of the amount of heat these particles generate upon NIR laser irradiation. Comparing between three different AuNRs (38 × 11, 28 × 8, and 17 × 5 nm), we determined that the 28 × 8 nm AuNR is the most effective in plasmonic photothermal heat generation. These results encouraged us to carry out in vitro experiments to compare the PPTT efficacy of the different sized AuNRs. The 28 × 8 nm AuNR was found to be the most effective photothermal contrast agent for PPTT of human oral squamous cell carcinoma. This size AuNR has the best compromise between the total amount of light absorbed and the fraction of which is converted to heat. In addition, the distance at which the electric field extends from the particle surface is most ideal for this size AuNR, as it is sufficient to allow for coupling between the fields of adjacent particles in solution (i.e., particle aggregates), resulting in effective heating in solution.

XAV939: from a small inhibitor to a potent drug bioconjugate when delivered by gold nanoparticles.

Nanoparticles as potential drug delivery vectors are drawing more attention every day. Here, we used gold nanopspheres (AuNSs) to selectively target the Wnt signaling pathway in human oral squamous cell carcinoma (HSC-3) cells. In a previously conducted study, XAV939, a small inhibiter, was found to strongly regulate the Wnt pathway by inhibiting the tankyrase enzyme and subsequent stabilization of cytoplasmic axin levels. In the present study, conjugating XAV939 molecules to AuNSs is found to enhance its potency by at least 100 times over its free form in killing HSC-3 cancer cells. Additionally, XAV 939 uptake studies have demonstrated an enhanced XAV939 bioconjugate delivery to the targeted cells compared to the passive cellular diffusion of the free drug at the same concentration. Furthermore, our study revealed that drug delivery and cytotoxicity are directly related to the size of the functionalized nanoparticles.

Antimicrobial activity of water-soluble triazole phenazine clickamers against E. coli.

The antimicrobial potency of phenazine derivatives is attenuated by their inherently hydrophobic nature, complicating their use as antibiotic drugs. We have analyzed the cytotoxicity and mode of action of water-soluble bis-triazolyl phenazines against E. coli and a human epithelial (HaCat) cell line. We observed complete inhibition of bacterial growth over concentration ranges that do not affect the viability of human epithelial cells. Confocal fluorescence microscopy revealed a high degree of interaction between the phenazine compounds and E. coli, as well as evidence of membrane damage in phenazine-treated E. coli. Additional data suggests that the potency of these particular water-soluble phenazine compounds does not result from the production of reactive oxygen species, but rather from cytotoxic interference with metabolic electron-transfer cascades.

Chemosensitization of cancer cells via gold nanoparticle-induced cell cycle regulation.

We have previously shown that plasmonic nanoparticles conjugated with nuclear-targeting and cytoplasm-targeting peptides (NLS and RGD, respectively) are capable of altering the cell cycle of human oral squamous carcinoma cells (HSC-3). In the present work, we show that this regulation of the cell cycle can be exploited to enhance the efficacy of a common chemotherapeutic agent, 5-Fluorouracil, by pretreating cells with gold nanoparticles. Utilizing flow cytometry cell cycle analysis, we were able to quantify the 5-Fluorouracil efficacy as an accumulation of cells in the S phase with a depletion of cells in the G2/M phase. Two gold nanoparticle sizes were tested in this work; 30 nm with a surface plasmon resonance at 530 nm and 15 nm with a surface plasmon resonance at 520 nm. The 30 nm nuclear-targeted gold nanoparticles (NLS-AuNPs) showed the greatest 5-Fluorouracil efficacy enhancement when 5-Fluorouracil treatment (500 µm, 48 h) is preceded by a 24-h treatment with nanoparticles. In conclusion, we show that nuclear-targeted 30 nm gold nanoparticles enhance 5-Fluorouracil drug efficacy in HSC-3 cells via regulation of the cell cycle, a chemosensitization technique that could potentially be expanded to different cell lines and different chemotherapies.

Surface-enhanced Raman spectroscopy for real-time monitoring of reactive oxygen species-induced DNA damage and its prevention by platinum nanoparticles.

We have successfully demonstrated the potential of surface-enhanced Raman spectroscopy (SERS) in monitoring the real time damage to genomic DNA. To reveal the capabilities of this technique, we exposed DNA to reactive oxygen species (ROS), an agent that has been implicated in causing DNA double-strand breaks, and the various stages of free radical-induced DNA damage have been monitored by using SERS. Besides this, we showed that prompt DNA aggregation followed by DNA double-strand scission and residual damage to the DNA bases caused by the ROS could be substantially reduced by the protective effect of Pt nanocages and nearly cubical Pt nanopartcles. The antioxidant activity of Pt nanoparticles was further confirmed by the cell viability studies. On the basis of SERS results, we identified various stages involved in the mechanism of action of ROS toward DNA damage, which involves the DNA double-strand scission and its aggregation followed by the oxidation of DNA bases. We found that Pt nanoparticles inhibit the DNA double-strand scission to a significant extent by the degradation of ROS. Our method illustrates the capability of SERS technique in giving vital information about the DNA degradation reactions at molecular level, which may provide insight into the effectiveness and mechanism of action of many drugs in cancer therapy.

Inducing cancer cell death by targeting its nucleus: solid gold nanospheres versus hollow gold nanocages.

Recently, we have shown that targeting the cancer cell nucleus with solid gold nanospheres, using a cancer cell penetrating/pro-apoptotic peptide (RGD) and a nuclear localization sequence peptide (NLS), inhibits cell division, thus leading to apoptosis. In the present work, flow cytometric analysis revealed an increase in cell death, via apoptosis and necrosis, in HSC cells upon treatment with peptide-conjugated hollow gold nanocages, compared to those treated with the peptide-conjugated solid gold nanospheres. This is consistent with a G0/G1 phase accumulation, S phase depletion, and G2/M phase depletion, as well as reduced ATP levels. Here, we investigate the possible causes for the observed enhanced cell death with the use of confocal microscopy. The fluorescence images of HSC cells treated with gold nanocages indicate the presence of reactive oxygen species, known to cause apoptosis. The formation of reactive oxygen species observed is consistent with a mechanism involving the oxidation of metallic silver on the inner cavity of the nanocage (inherent to the synthesis of the gold nanocages) to silver oxide. This oxidation is confirmed by an observed redshift in the surface plasmon resonance of the gold nanocages in cell culture medium. The silver oxide, a semiconductor known to photochemically generate hydroxyl radicals, a form of reactive oxygen species, is proposed as a mechanism for the enhanced cell death caused by gold nanocages. Thus, the enhanced cell death, via apoptosis and necrosis, observed with peptide-conjugated hollow gold nanocage-treated cells is considered to be a result of the metallic composition (silver remaining on the inner cavity) of the nanocage.

Probing the unique dehydration-induced structural modifications in cancer cell DNA using surface enhanced Raman spectroscopy.

Conformation-induced formation of a series of unique Raman marker bands in cancer cell DNA, upon dehydration, have been probed for the first time with the use of surface enhanced Raman spectroscopy (SERS). These bands are capable of distinguishing cancer cell DNA from healthy cell DNA. For this simple and label-free DNA detection approach, we used conventional spherical silver nanoparticles, at a high concentration, without any aggregating agents, which gave highly reproducible SERS spectra of DNA separated from various human cells irrespective of their highly complex compositions and sequences. The observed phenomenon is attributed to the change in the chemical environment due to the presence of nucleobase lesions in cancer cell DNA and subsequent variation in the nearby electronic cloud during the dehydration-driven conformational changes. Detailed analysis of the SERS spectra gave important insight about the lesion-induced structural modifications upon dehydration in the cancer cell DNA. These results have widespread implications in cancer diagnostics, where SERS provides vital information about the DNA modifications in the cancer cells.

Size matters: gold nanoparticles in targeted cancer drug delivery.

Cancer is the current leading cause of death worldwide, responsible for approximately one quarter of all deaths in the USA and UK. Nanotechnologies provide tremendous opportunities for multimodal, site-specific drug delivery to these disease sites and Au nanoparticles further offer a particularly unique set of physical, chemical and photonic properties with which to do so. This review will highlight some recent advances, by our laboratory and others, in the use of Au nanoparticles for systemic drug delivery to these malignancies and will also provide insights into their rational design, synthesis, physiological properties and clinical/preclinical applications, as well as strategies and challenges toward the clinical implementation of these constructs moving forward.

Beating cancer in multiple ways using nanogold.

Gold nanoparticles possess a unique combination of properties which allow them to act as highly multifunctional anti-cancer agents (X. H. Huang, P. K. Jain, I. H. El-Sayed and M. A. El-Sayed, Nanomedicine, 2007, 2, 681-693; P. Ghosh, G. Han, M. De, C. K. Kim and V. M. Rotello, Adv. Drug Delivery Rev., 2008, 60, 1307-1315; S. Lal, S. E. Clare and N. J. Halas, Acc. Chem. Res., 2008, 41, 1842-1851; D. A. Giljohann, D. S. Seferos, W. L. Daniel, M. D. Massich, P. C. Patel and C. A. Mirkin, Angew. Chem., Int. Ed., 2010, 49, 3280-3294). Not only can they be used as targeted contrast agents for photothermal cancer therapy, they can serve as scaffolds for increasingly potent cancer drug delivery, as transfection agents for selective gene therapy, and as intrinsic antineoplastic agents. This tutorial review will highlight some of the many forms and recent applications of these gold nanoparticle conjugates by our lab and others, as well as their rational design and physiologic interactions.

Remote triggered release of doxorubicin in tumors by synergistic application of thermosensitive liposomes and gold nanorods.

Delivery of chemotherapeutic agents after encapsulation in nanocarriers such as liposomes diminishes side-effects, as PEGylated nanocarrier pharmacokinetics decrease dosing to healthy tissues and accumulate in tumors due to the enhanced permeability and retention effect. Once in the tumor, however, dosing of the chemotherapeutic to tumor cells is limited potentially by the rate of release from the carriers and the size-constrained, poor diffusivity of nanocarriers in tumor interstitium. Here, we report the design and fabrication of a thermosensitive liposomal nanocarrier that maintains its encapsulation stability with a high concentration of doxorubicin payload, thereby minimizing "leak" and attendant toxicity. When used synergistically with PEGylated gold nanorods and near-infrared stimulation, remote triggered release of doxorubicin from thermosensitive liposomes was achieved in a mouse tumor model of human glioblastoma (U87), resulting in a significant increase in efficacy when compared to nontriggered or nonthermosensitive PEGylated liposomes. This enhancement in efficacy is attributed to increase in tumor-site apoptosis, as was evident from noninvasive apoptosis imaging using Annexin-Vivo 750 probe. This strategy affords remotely triggered control of tumor dosing of nanocarrier-encapsulated doxorubicin without sacrificing the ability to differentially dose drugs to tumors via the enhanced permeation and retention effect.

Comparative study of photothermolysis of cancer cells with nuclear-targeted or cytoplasm-targeted gold nanospheres: continuous wave or pulsed lasers.

We conduct a comparative study on the efficiency and cell death pathways of continuous wave (cw) and nanosecond pulsed laser photothermal cancer therapy using gold nanospheres delivered to either the cytoplasm or nucleus of cancer cells. Cytoplasm localization is achieved using arginine-glycine-aspartate peptide modified gold nanospheres, which target integrin receptors on the cell surface and are subsequently internalized by the cells. Nuclear delivery is achieved by conjugating the gold nanospheres with nuclear localization sequence peptides originating from the simian virus. Photothermal experiments show that cell death can be induced with a single pulse of a nanosecond laser more efficiently than with a cw laser. When the cw laser is applied, gold nanospheres localized in the cytoplasm are more effective in inducing cell destruction than gold nanospheres localized at the nucleus. The opposite effect is observed when the nanosecond pulsed laser is used, suggesting that plasmonic field enhancement of the nonlinear absorption processes occurs at high localization of gold nanospheres at the nucleus. Cell death pathways are further investigated via a standard apoptosis kit to show that the cell death mechanisms depend on the type of laser used. While the cw laser induces cell death via apoptosis, the nanosecond pulsed laser leads to cell necrosis. These studies add mechanistic insight to gold nanoparticle-based photothermal therapy of cancer.

Nuclear targeting of gold nanoparticles in cancer cells induces DNA damage, causing cytokinesis arrest and apoptosis.

By properly conjugating gold nanoparticles with specific peptides, we were successful in selectively transporting them to the nuclei of cancer cells. Confocal microscopy images of DNA double-strand breaks showed that localization of gold nanoparticles at the nucleus of a cancer cell damages the DNA. Gold nanoparticle dark-field imaging of live cells in real time revealed that the nuclear targeting of gold nanoparticles specifically induces cytokinesis arrest in cancer cells, where binucleate cell formation occurs after mitosis takes place. Flow cytometry results indicated that the failure to complete cell division led to programmed cell death (apoptosis) in cancer cells. These results show that gold nanoparticles localized at the nuclei of cancer cells have important implications in understanding the interaction between nanomaterials and living systems.

Formal DNA hydrolysis by mono- and dinuclear iron complexes.

The complexes CpFe(CO)(2)Ph and [CpFe(CO)(2)](2) cleave DNA in the presence of H2O2 or organic peroxides to give products resulting from the formal hydrolysis of the phosphodiester groups.