Doxorubicin Encapsulation in Carbon Nanotubes Having Haeckelite or Stone-Wales Defects as Drug Carriers: A Molecular Dynamics Approach.

Doxorubicin (DOX), a recognized anticancer drug, forms stable associations with carbon nanotubes (CNTs). CNTs when properly functionalized have the ability to anchor directly in cancerous tumors where the release of the drug occurs thanks to the tumor slightly acidic pH. Herein, we study the armchair and zigzag CNTs with Stone-Wales (SW) defects to rank their ability to encapsulate DOX by determining the DOX-CNT binding free energies using the MM/PBSA and MM/GBSA methods implemented in AMBER16. We investigate also the chiral CNTs with haeckelite defects. Each haeckelite defect consists of a pair of square and octagonal rings. The armchair and zigzag CNT with SW defects and chiral nanotubes with haeckelite defects predict DOX-CNT interactions that depend on the length of the nanotube, the number of present defects and nitrogen doping. Chiral nanotubes having two haeckelite defects reveal a clear dependence on the nitrogen content with DOX-CNT interaction forces decreasing in the order 0N > 4N > 8N. These results contribute to a further understanding of drug-nanotube interactions and to the design of new drug delivery systems based on CNTs.

Carbon Nanotubes Having Haeckelite Defects as Potential Drug Carriers. Molecular Dynamics Simulation.

Carbon nanotubes (CNTs) are valuable drug carriers since when properly functionalized they transport drugs and anchor directly to cancerous tumors whose more acidic pH causes the drug release. Herein, we study the so-called zigzag and armchair CNTs with haeckelite defects to rank their ability to adsorb doxorubicin (DOX) by determining the DOX-CNT binding free energies using the MM/PBSA and MM/GBSA methods implemented in AMBER. Our results reveal stronger DOX-CNT interactions for encapsulation of the drug inside the nanotube compared to its adsorption onto the defective nanotube external surface. Armchair CNTs with one and two defects exhibit better results compared with those with four and fifteen defects. Each haeckelite defect consists of a pair of square and octagonal rings. DOX-CNT binding free energies are predicted to be dependent on: (i) nanotube chirality and diameter, (ii) the number of defects, (iii) nitrogen doping and (iv) the position of the encapsulated DOX inside the nanotube. Armchair (10,10) nanotubes with two haeckelite defects, doped with nitrogen, exhibit the best drug-nanotube binding free energies compared with zigzag and fully hydrogenated nanotubes and, also previously reported ones with bumpy defects. These results contribute to further understanding drug-nanotube interactions and their potential application to the design of new drug delivery systems.

Pseudotumor hemofílico del calcáneo / Pseudotumor hemophilic of the calcaneus

El pseudotumor hemofílico del calcáneo es una complicación infrecuente de la hemofilia grave. Tiene una incidencia del 1 a 2%, en pacientes que han presentado traumatismos repetidos a nivel del talón, manifestándose con mayor frecuencia entre los 20 a 70 años. Se presenta el caso clínico de un paciente masculino de 20 años de edad, portador de Hemofilia sin tratamiento específico con antecedente de múltiples traumatismos en talón derecho de dos años de evolución con hematomas localizados sin recibir tratamiento, evolucionando a la formación de una masa a nivel de talón compatible con un pseudotumor hemofílico del calcáneo. El diagnóstico de esta patología se basa en la historia clínica del paciente, laboratorios y estudios de imagen para definir la localización, características, extensión e invasión a estructuras vecinas. Existen diferentes opciones de tratamiento, siendo indispensable el manejo inicial de la hemorragia aguda o crónica con el respectivo reemplazo del factor deficiente.

The calcaneal hemophilic pseudotumor is a rare complication of severe hemophilia. It has an incidence of 1-2% in patients who have recurrent trauma to the heel, manifesting most often between 20-70 years. We report the case of a male patient, 20 years old, carrier of Hemophilia without specific treatment with a history of multiple traumas in right heel two years of evolution with untreated localized bruising, evolving to the formation of a mass level heel supports a hemophilic pseudotumor of the calcaneus. The diagnosis of this disease is based on patient history, laboratory and imaging studies to define the location, characteristics, extent and invasion of neighboring structures. There are different treatment options, the initial management of acute or chronic bleeding with the corresponding replacement of the deficient factor being indispensable.