Low-energy-loss electron microscopy of doxorubicin in human breast cancer MCF-7 cells: localization by color

Stable Configurations of DOXH Interacting with Graphene: Heuristic Algorithm Approach Using NSGA-II and U-NSGA-III

Nanoparticles in drug delivery have been widely studied and have become a potential technique for cancer treatment. Doxorubicin (DOX) and carbon graphene are candidates as a drug and a nanocarrier, respectively, and they can be modified or decorated by other molecular functions to obtain more controllable and stable systems. A number of researchers focus on investigating the energy, atomic distance, bond length, system formation and their properties using density function theory and molecular dynamic simulation. In this study, we propose metaheuristic optimization algorithms, NSGA-II and U-NSGA-III, to find the interaction energy between DOXH molecules and pristine graphene in three systems: (i) interacting between two DOXHs, (ii) one DOXH interacting with graphene and (iii) two DOXHs interacting with graphene. The result shows that the position of the carbon ring plane of DOXH is noticeably a key factor of stability. In the first system, there are three possible, stable configurations where their carbon ring planes are oppositely parallel, overlapping and perpendicular. In the second system, the most stable configuration is the parallel form between the DOXH carbon ring plane and graphene, and the spacing distance from the closest atom on the DOXH to the graphene is 2.57 Å. In the last system, two stable configurations are formed, where carbon ring planes from the two DOXHs lie either in the opposite direction or in the same direction and are parallel to the graphene sheet. All numerical results show good agreement with other studies.

Fullerene-conjugated doxorubicin in cells

The conjugation of fullerene with well-established drug molecules has been a representative strategy to impart fullerene-specific properties for improved formulation. However, conjugates involving fullerenes or other nanomaterials often differ significantly from the free drug molecules in cellular uptake and distributions. For the highly effective anticancer drug doxorubicin (DOX), its strong absorption and fluorescence in the visible spectral region enable the tracking of DOX-containing conjugates by optical techniques. In this work, a stoimetrically and structurally well-defined fullerene-DOX conjugate was studied in terms of fluorescence microscopy, including the fluorescence imaging with two-photon excitation, to examine the uptake and distribution in human breast cancer cells. The results suggested that the conjugate was distributed mostly in the cytoplasm, significantly different from free DOX molecules (predominantly in the cell nucleus, as already reported in the literature). Mechanistic implications of the results are discussed. Also discussed are potentials of conjugated DOX species as self-labeled fluorescent probes in bioimaging and other mechanistic investigations on drug delivery.

New doxorubicin-loaded phospholipid microbubbles for targeted tumor therapy: Part I--Formulation development and in-vitro characterization

Despite high antitumor efficacy and a broad application spectrum, clinical treatment with anthracycline chemotherapeutics is often limited by severe adverse effects such as cardiotoxicity and myelosupression. In recent years, tumor drug targeting has evolved as a promising strategy to increase local drug concentration and reduce systemic side effects. One recent approach for targeting solid tumors is the application of microbubbles, loaded with chemotherapeutic drugs. These advanced drug carriers can be safely administered to the patient by intravenous infusion, and will circulate through the entire vasculature. Their drug load can be locally released by ultrasound targeted microbubble destruction. In addition, tumors can be precisely localized by diagnostic ultrasound since microbubbles act as contrast agents. In the present work a novel microbubble carrier for doxorubicin has been developed and characterized in-vitro. In contrast to many recent tumor-targeting MB designs the newly developed doxorubicin-loaded microbubbles possess a soft but stable phospholipid monolayer shell. Importantly, the active drug is embedded in the microbubble shell and is complexed to the phospholipids by both electrostatic and hydrophobic interactions. Despite their drug load, these novel microbubbles retained all important physical characteristics for ultrasound targeted microbubble destruction, comparable with the commercially available ultrasound contrast agents. In cell culture studies doxorubicin-loaded microbubbles in combination with ultrasound demonstrated an about 3 fold increase of the anti-proliferative activity compared to free doxorubicin and doxorubicin-loaded liposomes. For the first time in the literature the intracellular partition of free doxorubicin and phospholipid-complexed doxorubicin were compared. In conclusion, new doxorubicin-loaded microbubbles with ideal physical characteristics were developed. In-vitro studies show enhanced cytotoxic activity compared to free doxorubicin and doxorubicin-loaded liposomes.

Visualization and quantitative analysis of nanoparticles in the respiratory tract by transmission electron microscopy

Nanotechnology in its widest sense seeks to exploit the special biophysical and chemical properties of materials at the nanoscale. While the potential technological, diagnostic or therapeutic applications are promising there is a growing body of evidence that the special technological features of nanoparticulate material are associated with biological effects formerly not attributed to the same materials at a larger particle scale. Therefore, studies that address the potential hazards of nanoparticles on biological systems including human health are required. Due to its large surface area the lung is one of the major sites of interaction with inhaled nanoparticles. One of the great challenges of studying particle-lung interactions is the microscopic visualization of nanoparticles within tissues or single cells both in vivo and in vitro. Once a certain type of nanoparticle can be identified unambiguously using microscopic methods it is desirable to quantify the particle distribution within a cell, an organ or the whole organism. Transmission electron microscopy provides an ideal tool to perform qualitative and quantitative analyses of particle-related structural changes of the respiratory tract, to reveal the localization of nanoparticles within tissues and cells and to investigate the 3D nature of nanoparticle-lung interactions.This article provides information on the applicability, advantages and disadvantages of electron microscopic preparation techniques and several advanced transmission electron microscopic methods including conventional, immuno and energy-filtered electron microscopy as well as electron tomography for the visualization of both model nanoparticles (e.g. polystyrene) and technologically relevant nanoparticles (e.g. titanium dioxide). Furthermore, we highlight possibilities to combine light and electron microscopic techniques in a correlative approach. Finally, we demonstrate a formal quantitative, i.e. stereological approach to analyze the distributions of nanoparticles in tissues and cells.This comprehensive article aims to provide a basis for scientists in nanoparticle research to integrate electron microscopic analyses into their study design and to select the appropriate microscopic strategy.