Owing to their unique mechanical, electrical, optical, and thermal properties, carbon nanostructures including carbon nanotubes and graphenes show great promise for advancing the fields of biology and medicine. Many reports have demonstrated the promise of these carbon nanostructures and their hybrid structures (composites with polymers, ceramics, and metal nanoparticles, etc.) for a variety of biomedical areas ranging from biosensing, drug delivery, and diagnostics, to cancer treatment, tissue engineering, and bioterrorism prevention. However, the issue of the safety and toxicity of these carbon nanostructures, which is vital to their use as diagnostic and therapeutic tools in biomedical fields, has not been completely resolved. This paper aims to provide a summary of the features of carbon nanotube and graphene-based materials and current research progress in biomedical applications. We also highlight the current opinions within the scientific community on the toxicity and safety of these carbon structures.

We present a semi-analytical study exploring the end-fire coupling of an incident beam into a surface plasmon mode propagating on a metal-dielectric interface. An energy-conserving projection method is used to solve for the resultant reflected and transmitted fields for a given incident beam, thereby determining the efficiency of the surface plasmon coupling. The coupling efficiency is found to be periodic with waveguide width due to the presence of a transversely propagating surface plasmon. Optimisation of the incident beam parameters, such as beam width, position and wavelength leads to numerically observed maximum efficiencies of approximately 80% when the beam width roughly matches the width of the surface plasmon.

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