66 research outputs found
XSEDE: eXtreme Science and Engineering Discovery Environment Third Quarter 2012 Report
The Extreme Science and Engineering Discovery Environment (XSEDE) is the most advanced, powerful, and robust collection of integrated digital resources and services in the world. It is an integrated cyberinfrastructure ecosystem with singular interfaces for allocations, support, and other key services that researchers can use to interactively share computing resources, data, and expertise.This a report of project activities and highlights from the third quarter of 2012.National Science Foundation, OCI-105357
Properties and Applications of Graphene and Its Derivatives
Graphene is a two-dimensional, one-atom-thick material made entirely of carbon atoms, arranged in a honeycomb lattice. Because of its distinctive mechanical (e.g., high strength and flexibility) and electronic (great electrical and thermal conductivities) properties, graphene is an ideal candidate in myriad applications. Thus, it has just begun to be engineered in electronics, photonics, biomedicine, and polymer-based composites, to name a few. The broad family of graphene nanomaterials (including graphene nanoplatelets, graphene oxide, graphene quantum dots, and many more) go beyond and aim higher than mere single-layer (‘pristine’) graphene, and thus, their potential has sparked the current Special Issue. In it, 18 contributions (comprising 14 research articles and 4 reviews) have portrayed probably the most interesting lines as regards future and tangible uses of graphene derivatives. Ultimately, understanding the properties of the graphene family of nanomaterials is crucial for developing advanced applications to solve important challenges in critical areas such as energy and health
Molecular modeling of drug delivery systems based on carbon nanostructures: structure, function, and potential applications for anticancer complexes of Pt(II)
The medication with Pt(II) drugs (cisplatin, carboplatin, and oxaliplatin) has been an effective
alternative for treating cancers due to their notable inhibition of cancer cells growth and the
prevention of metastasis. Nevertheless, the low selectivity of these metallodrugs for malignant
cells produces severe side effects, which limit this chemotherapy. In this context, carbon
nanohorns (CNHs) have been considered potential nanovectors for drugs, since they present
low toxicity, drug-loading capacity, biodegradation routes, and biocompatibility when
oxidized. However, there is still a lack of studies regarding the molecular behavior of these
nanocarriers on cell membranes. The present work aims to characterize the interactions between
inclusion complexes drug@CNH, which are formed by platinum drugs encapsulated in CNHs,
and plasma membranes by using molecular dynamics simulations. The results demonstrated
that the van der Waals contribution played a primary role (∼74%) for the complex stability,
which explain the confined dynamics of drugs inside the CNHs. The free energy profiles
revealed an endergonic character of the drug release processes from CNHs, in which the energy
barrier for oxaliplatin release (~24 kcal mol–1
) was ~30% larger than those for carboplatin and
cisplatin (~18 kcal mol-1
). The simulations also showed four stages of the interaction
mechanism CNH--membrane: approach, insertion, permeation, and internalization. Despite the
low structural disturbance of the membranes, the free energy barrier of ∼55 kcal mol-1 for the
CNHs translocation indicated that this transport is kinetically unfavorable by passive process.
The in silico experiments evidenced that the most likely mechanism of cisplatin delivery from
CNHs involve the approach and insertion stages, where the nanovector adheres on the surface
of cancer cells, as reported in in vitro studies. After this retention, the drug load may be slowly
released in the tumor site. Finally, simulations of the cellular uptake of Pt(II) drugs also pointed
out significant energy barriers (~30 kcal mol-1
) for this process, which reflects their low
permeability in membranes as discussed in experimental studies. In addition to reinforcing the
potential of CNH as nanovector of Pt(II) drugs, the results presented in this thesis may assist
and drive new experimental studies with CNHs, focusing on the development of less aggressive
formulations for cancer treatments.A medicação com fármacos a base de Pt(II) (cisplatina, carboplatina e oxaliplatina) tem sido
uma alternativa efetiva para tratar cânceres devido à sua notável inibição do crescimento de
células cancerosas e a prevenção de metástases. No entanto, a baixa seletividade dessas
metalodrogas por células cancerosas gera severos efeitos colaterais. Nesse contexto, nanohorns
de carbono (CNHs) têm sido considerados potenciais nanovetores de fármacos, devido a baixa
toxicidade, capacidade de carreamento de fármacos, rotas de biodegradação, e
biocompatibilidade quando oxidados. Porém, existe uma carência de estudos tratando o
comportamento desses nanocarreadores em biomembranas. Esse trabalho tem como objetivo
caracterizar as interações entre complexos de inclusão fármaco@CNH, formados por fármacos
de Pt(II) encapsulados em CNHs, e membranas usando simulações por dinâmica molecular. Os
resultados demonstraram que a contribuição de van der Waals teve um papel primário (∼74%)
na estabilidade dos complexos, o que explica a dinâmica confinada dos fármacos dentro dos
CNHs. Os perfis de energia livre revelaram o caráter endergônico da liberação dos fármacos a
partir de CNHs, nos quais a barreira de energia para a liberação da oxaliplatina (~24 kcal mol–
1
) é ~30% maior do que aquelas para carboplatina e cisplatina. As simulações mostraram quatro
estágios do mecanismo de interação CNH-membrana: aproximação, inserção, permeação e
internalização. Apesar do baixo distúrbio estrutural das membranas, a barreira de energia livre
de ∼55 kcal mol-1 para a translocação de CNHs indicou que esse transporte é desfavorável
cineticamente via o processo passivo. Os experimentos in silico evidenciam que o mecanismo
mais provável de entrega de cisplatina a partir de CNHs envolve a aproximação e inserção,
onde o nanovetor adere na superfície de células cancerosas, como reportado em estudos in vitro.
Após essa retenção, a carga de fármaco deve ser ligeiramente liberada no tumor. As simulações
de captação celular de fármacos de Pt(II) também apontaram barreiras de energia significativas
(∼30 kcal mol-1
) para esse processo, o que reflete a baixa permeabilidade deles em membranas
como discutido em estudos experimentais. Além de reforçar o potencial de CNHs como
nanovetores de fármacos de Pt(II), os resultados apresentados nessa tese podem auxiliar e
impulsionar novos estudos com CNHs, focando no desenvolvimento de formulações menos
agressivas para tratamentos de câncer.FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerai
ICR ANNUAL REPORT 2022 (Volume 29)[All Pages]
This Annual Report covers from 1 January to 31 December 202
Inverted Colloidal Crystal Scaffolds New Substitutes for Bone Tissue Engineering
Bone is a highly organised and specialised connective tissue with natural ability to
self-heal and regain functionality. This capacity is, however, exposed to a great number of
threats that can critically damage bone’s health and trigger the need for bone substitutes.
The present thesis aimed at the production of new bone scaffolds for tissue regeneration
using the Inverted Colloidal Crystal (ICC) structure as model system. ICCs are
3D structures, resultant from Colloidal Crystals (CC) inverse replication, that exhibit
uniform pore size, interconnected network and whose architectural design enhances the
cellular environment and vascular ingrowth.
Reported here is the use of organic (chitosan/chitin nanowhiskers) and inorganic
(hydroxyapatite) building materials to develop scaffolds comprising ceramic, polymeric
and composite matrices. Firstly, polystyrene microspheres are produced by simple microfluidic,
assembled in hexagonal close packed CC and then used as templates for all
scaffolds production. Ceramic based ICCs were developed using an hydroxyapatite solgel
system and sintering route that allowed simultaneous template calcination and matrix
formation. Polymeric based ICCs were subjected to hydrolytic degradation after being
produced with different molecular weight chitosans in order to understand polymer influence
on the scaffolds structural stability. Considering bone´s composite nature, ICCs
were constructed using hydroxyapatite nanorods suspended in chitosan solutions. Also,
structures whose materials have an imprinted liquid crystalline organization provided
by chitin nanowhiskers were developed inspired by bone collagen arrangement that contributes
to the tissue hierarchical architecture.
The morphological, biological and mechanical evaluation of such scaffolds contributes
to establish the path for the development of new ICC based products with potential to
complement or replace the currently clinically used bone substitutes and in that way
constitute valuable solutions for bone tissue regeneration
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