1s2p resonant inelastic X-ray scattering combined dipole and quadrupole analysis method.

In this study an analysis strategy towards using the resonant inelastic X-ray scattering (RIXS) technique more effectively compared with X-ray absorption spectroscopy (XAS) is presented. In particular, the question of when RIXS brings extra information compared with XAS is addressed. To answer this question the RIXS plane is analysed using two models: (i) an exciton model and (ii) a continuum model. The continuum model describes the dipole pre-edge excitations while the exciton model describes the quadrupole excitations. Applying our approach to the experimental 1s2p RIXS planes of VO2 and TiO2, it is shown that only in the case of quadrupole excitations being present is additional information gained by RIXS compared with XAS. Combining this knowledge with methods to calculate the dipole contribution in XAS measurements gives scientists the opportunity to plan more effective experiments.

Combining Stimulus-Triggered Release and Active Targeting Strategies Improves Cytotoxicity of Cytochrome c Nanoparticles in Tumor Cells.

Proteins often possess highly specific biological activities that make them potential therapeutics, but their physical and chemical instabilities during formulation, storage, and delivery have limited their medical use. Therefore, engineering of nanosized vehicles to stabilize protein therapeutics and to allow for targeted treatment of complex diseases, such as cancer, is of considerable interest. A micelle-like nanoparticle (NP) was designed for both, tumor targeting and stimulus-triggered release of the apoptotic protein cytochrome c (Cyt c). This system is composed of a Cyt c NP stabilized by a folate-receptor targeting amphiphilic copolymer (FA-PEG-PLGA) attached to Cyt c through a redox-sensitive bond. FA-PEG-PLGA-S-S-Cyt c NPs exhibited excellent stability under extracellular physiological conditions, whereas once in the intracellular reducing environment, Cyt c was released from the conjugate. Under the same conditions, the folate-decorated NP reduced folate receptor positive HeLa cell viability to 20%, while the same complex without FA only reduced it to 80%. Confocal microscopy showed that the FA-PEG-PLGA-S-S-Cyt c NPs were internalized by HeLa cells and were capable of endosomal escape. The specificity of the folate receptor-mediated internalization was confirmed by the lack of uptake by two folate receptor deficient cell lines: A549 and NIH-3T3. Finally, the potential as antitumor therapy of our folate-decorated Cyt c-based NPs was confirmed with an in vivo brain tumor model. In conclusion, we were able to create a stable, selective, and smart nanosized Cyt c delivery system.

Activation of caspase-dependent apoptosis by intracellular delivery of Cytochrome c-based nanoparticles.

BACKGROUND: Cytochrome c is an essential mediator of apoptosis when it is released from the mitochondria to the cytoplasm. This process normally takes place in response to DNA damage, but in many cancer cells (i.e., cancer stem cells) it is disabled due to various mechanisms. However, it has been demonstrated that the targeted delivery of Cytochrome c directly to the cytoplasm of cancer cells selective initiates apoptosis in many cancer cells. In this work we designed a novel nano-sized smart Cytochrome c drug delivery system to induce apoptosis in cancer cells upon delivery. RESULTS: Cytochrome c was precipitated with a solvent-displacement method to obtain protein nanoparticles. The size of the Cytochrome c nanoparticles obtained was 100-300 nm in diameter depending on the conditions used, indicating good potential to passively target tumors by the Enhanced Permeability and Retention effect. The surface of Cytochrome c nanoparticles was decorated with poly (lactic-co-glycolic) acid-SH via the linker succinimidyl 3-(2-pyridyldithio) propionate to prevent premature dissolution during delivery. The linker connecting the polymer to the protein nanoparticle contained a disulfide bond thus allowing polymer shedding and subsequent Cytochrome c release under intracellular reducing conditions. A cell-free caspase-3 assay revealed more than 80% of relative caspase activation by Cytochrome c after nanoprecipitation and polymer modification when compared to native Cytochrome c. Incubation of HeLa cells with the Cytochrome c based-nanoparticles showed significant reduction in cell viability after 6 hours while native Cytochrome c showed none. Confocal microscopy confirmed the induction of apoptosis in HeLa cells when they were stained with 4',6-diamidino-2-phenylindole and propidium iodide after incubation with the Cytochrome c-based nanoparticles. CONCLUSIONS: Our results demonstrate that the coating with a hydrophobic polymer stabilizes Cytochrome c nanoparticles allowing for their delivery to the cytoplasm of target cells. After smart release of Cytochrome c into the cytoplasm, it induced programmed cell death.

Closing extraction spaces with lingual orthodontics.

There are different ways of closing extraction spaces with lingual orthodontics. One is to use loop mechanics and the other is to use sliding mechanics. This case report describes the treatment of closing spaces using sliding mechanics with and without the use of microscrews. Understanding and applying basic biomechanical principles is necessary for lingual orthodontics and the use of miniscrews. The purpose of this article is to demonstrate the effect of orthodontic miniscrews in controlling anchorage and the basic biomechanical considerations in understanding the influence of the anterior teeth.

Smart Targeting To Improve Cancer Therapeutics.

Cancer is the second largest cause of death worldwide with the number of new cancer cases predicted to grow significantly in the next decades. Biotechnology and medicine can and should work hand-in-hand to improve cancer diagnosis and treatment efficacy. However, success has been frequently limited, in particular when treating late-stage solid tumors. There still is the need to develop smart and synergistic therapeutic approaches to achieve the synthesis of strong and effective drugs and delivery systems. Much interest has been paid to the development of smart drug delivery systems (drug-loaded particles) that utilize passive targeting, active targeting, and/or stimulus responsiveness strategies. This review will summarize some main ideas about the effect of each strategy and how the combination of some or all of them has shown to be effective. After a brief introduction of current cancer therapies and their limitations, we describe the biological barriers that nanoparticles need to overcome, followed by presenting different types of drug delivery systems to improve drug accumulation in tumors. Then, we describe cancer cell membrane targets that increase cellular drug uptake through active targeting mechanisms. Stimulus-responsive targeting is also discussed by looking at the intra- and extracellular conditions for specific drug release. We include a significant amount of information summarized in tables and figures on nanoparticle-based therapeutics, PEGylated drugs, different ligands for the design of active-targeted systems, and targeting of different organs. We also discuss some still prevailing fundamental limitations of these approaches, eg, by occlusion of targeting ligands.

New method for analysis of nanoparticle geometry in supported fcc metal catalysts with scanning transmission electron microscopy.

To apply the knowledge of reaction mechanisms of heterogeneously catalyzed reactions on the atomic scale to supported catalyst systems, a detailed description of the structure of active particles on the atomic scale is required. In this article, a method is developed to construct atomic-scale geometric models for supported active fcc metal nanoparticles, based on a measurement of particle sizes and particle volumes by Scanning Transmission Electron Microscopy (STEM) and the M-M coordination number determined from EXAFS. The method is applied to supported Au/TiO(2), Au/MgAl(2)O(4)(-), and Au/Al(2)O(3) catalysts. These geometric models allow for estimation of geometric properties, such as specific Au surface area, metal-support contact perimeter, metal-support contact surface area, edge length, and number of Au atoms located at the corners of the particles, with an error on the order of 20%. In the three catalysts studied here we find that the Au particles in the Al(2)O(3) supported catalyst are small. The Au particles in the Au/TiO(2) catalyst are smaller in diameter than those for the Au/MgAl(2)O(4), but also thicker. The differences in particle size and shape seem to reflect the differences in the metal-support interface energy in the three catalyst systems.

Redox-sensitive cross-linking enhances albumin nanoparticle function as delivery system for photodynamic cancer therapy.

Photodynamic cancer therapy is still limited in its efficiency because of a lack of targeted methods avoiding non-specific toxicity. To overcome this we developed a system that is solely effective upon cellular uptake and intracellular activation by incorporating redox-sensitive chemistry. We used a nanoprecipitation method to obtain human serum albumin nanoparticles (HSA NP) with a diameter of 295 ± 5 nm and decorated them with the photosensitizer (PS) chlorin e6 (Ce6). The NP were stabilized using a redox-sensitive cross-linker to create a smart drug delivery system that is activated only upon NP disintegration in the reducing intracellular environment. Indeed, our drug delivery NP broke down in an environment emulating the reducing intracellular environment with 10 mM glutathione, but not under extracellular conditions. In contrast, the control cross-linked with glutaraldehyde did not break down in the reducing environment. Upon NP disintegration Ce6 fluorescence doubled as the result of diminished self-quenching. While the Ce6-HSA NP did not produce a significant amount of singlet oxygen upon irradiation, NP disintegration restored singlet oxygen production to about half of the value generated by the free Ce6. In vitro experiments with HeLa cells showed that the smart system was able to kill up to 81% of the cells while the glutaraldehyde cross-linked control only killed 56% of them at a drug concentration of 10 ng/ml. Also, Ce6 immobilization in HSA NP prevented dark toxicity in three different cell lines. For the first time, we demonstrate that it is possible to design a smart NP drug delivery system delivering a PS drug to cancer cells while avoiding toxicity prior to the uptake and irradiation. This finding may provide a means of designing more efficient PDT in cancer treatment.

Induction of Cancer Cell Death by Hyaluronic Acid-Mediated Uptake of Cytochrome C.

Effective cancer treatment needs both, passive and active targeting approaches, to achieve highly specific drug delivery to the target cells while avoiding cytotoxicity to normal cells. Protein drugs are useful in this context because they can display excellent specificity and potency. However, their use in therapeutic formulations is limited due to their physical and chemical instability during storage and administration. Polysaccharides have been used to stabilize proteins during formulation and delivery. To accomplish both, stabilization and targeting simultaneously, the apoptosis-inducing protein cytochrome c (Cyt c) was modified with the polysaccharide hyaluronic acid (HA) because its corresponding receptor CD44 is overexpressed in many cancers. Cyt c-HA bioconjugates were formed using low and high molecular weight HA (8 kDa and 1 MDa) with a resultant Cyt c loading percentage of 4%. Circular dichroism and a cell-free caspase assay showed minor structural changes and high bioactivity (more than 80% caspase activation) of Cyt c, respectively, after bioconjugate formation. Two CD44-positive cancer cells lines, HeLa and A549 cells, and two CD44-negative normal cell lines, Huvec and NIH-3T3 cells, were incubated with the samples to assess selectivity and cytotoxicity. After 24 h of incubation with the samples, cancer cell viability was reduced at least 3-fold while CD44-negative control cell lines remained minimally affected. Fluorescence imaging confirmed selective internalization of the Cyt c-HA construct by CD44-positive cancer cell lines. These results demonstrate the development of a drug delivery system that incorporates passive and active targeting which is essential for cancer treatment.