Graphene oxide nanoparticles for enhanced photothermal cancer cell therapy under the irradiation of a femtosecond laser beam.

Nano-sized graphene and graphene oxide (GO) are promising for biomedical applications, such as drug delivery and photothermal therapy of cancer. It is observed in this work that the ultrafast reduction of GO nanoparticles (GONs) with a femtosecond laser beam creates extensive microbubbling. To understand the surface chemistry of GONs on the microbubble formation, the GONs were reduced to remove most of the oxygen-containing groups to get reduced GONs (rGONs). Microbubbling was not observed when the rGONs were irradiated by the laser. The instant collapse of the microbubbles may produce microcavitation effect that brings about localized mechanical damage. To understand the potential applications of this phenomenon, cancer cells labeled with GONs or rGONs were irradiated with the laser. Interestingly, the microbubbling effect greatly facilitated the destruction of cancer cells. When microbubbles were produced, the effective laser power was reduced to less than half of what is needed when microbubbling is absent. This finding will contribute to the safe application of femtosecond laser in the medical area by taking advantage of the ultrafast reduction of GONs. It may also find other important applications that need highly localized microcavitation effects.

A review of optical imaging and therapy using nanosized graphene and graphene oxide.

Nanosized graphene and graphene oxide (GO) are photoluminescent due to the presence of bandgaps and edges/defects. The excellent photostability of these nanomaterials makes them superior to molecular dyes for biological imaging. They can also produce intensive heat under laser irradiation, enabling them to serve as photothermal agents for cancer treatment. In this work, recent studies on the photoluminescence of these materials, their applications for biological imaging and photothermal cancer therapy are reviewed. Properties of laser, particularly the temporal property (continuous wave or pulsed), affect its interaction with materials. Therefore, the photoluminescence and photothermal effects, as well as their applications under both single (one)-photon (continuous wave laser) and two-photon (pulsed laser) excitation were summarized and analyzed. Synergistic therapy which combines chemotherapy and photothermal therapy using these materials is also reviewed. Finally, critical issues and challenges for further research and in medical applications of these materials are analyzed.

Controlling nanoparticle formation via sizable cages of supramolecular soft materials.

We present a new generic strategy to fabricate nanoparticles in the "cages" within the fibrous networks of supramolecular soft materials. As the cages can be acquired by a design-and-production manner, the size of nanoparticles synthesized within the cages can be tuned accordingly. To implement this idea, both selenium and silver were chosen for the detailed investigation. It follows that the sizes of selenium and silver nanoparticles can be controlled by tuning the pore size of the fiber networks in the material. When the concentration of the gelator is high enough, monodisperse nanoparticles can be prepared. More interestingly, the morphology of the nanoparticles can be altered: silver disks can be formed when the concentrations of both the gelator and silver nitrate are sufficiently low. As the fiber network serves as a physical barrier and semisolid support for the nanoparticles, the stability in the aqueous media and the ease of application of these nanoparticles can be substantially enhanced. This robust surfactant-free approach will not only allow the controlled fabrication of nanoparticles, but also can be applied to the fabrication of composite materials for robust applications.