In this paper we report for the first time, the photoconductivity of large area sheets of single wall carbon nanotube upon laser illumination. The photoconductivity exhibited an increase, decrease or even 'negative' values when the laser spot was on different positions between contact electrodes, showing a 'position' dependent effect of photoconductivity. Photon induced charge carrier generation in single wall carbon nanotubes and subsequent charge separation across the metal-carbon nanotube contacts is believed to cause the photoconductivity changes. A net photovoltage of ∼10 mV and a photocurrent of ∼1.6 mA were produced under the laser intensity of ∼160 mW with a quantum efficiency of ∼1.5% in vacuum. The effect of the contact area between the electrodes and nanotubes, ambient pressure, laser intensity and light pulse frequency on the photoconductivity is discussed.

Molecular targeting and photodynamic therapy have shown great potential for selective cancer therapy. We hypothesized that monoclonal antibodies that are specific to the IGF1 receptor and HER2 cell surface antigens could be bound to single wall carbon nanotubes (SWCNT) in order to concentrate SWCNT on breast cancer cells for specific near-infrared phototherapy. SWCNT functionalized with HER2 and IGF1R specific antibodies showed selective attachment to breast cancer cells compared to SWCNT functionalized with non-specific antibodies. After the complexes were attached to specific cancer cells, SWCNT were excited by ∼808 nm infrared photons at ∼800 mW cm−2 for 3 min. Viability after phototherapy was determined by Trypan blue exclusion. Cells incubated with SWCNT/non-specific antibody hybrids were still alive after photo-thermal treatment due to the lack of SWNT binding to the cell membrane. All cancerous cells treated with IGF1R and HER2 specific antibody/SWCNT hybrids and receiving infrared photons showed cell death after the laser excitation. Quantitative analysis demonstrated that all the cells treated with SWCNT/IGF1R and HER2 specific antibody complex were completely destroyed, while more than 80% of the cells with SWCNT/non-specific antibody hybrids remained alive. Following multi-component targeting of IGF1R and HER2 surface receptors, integrated photo-thermal therapy in breast cancer cells led to the complete destruction of cancer cells. Functionalizing SWCNT with antibodies in combination with their intrinsic optical properties can therefore lead to a new class of molecular delivery and cancer therapeutic systems.

In this letter we demonstrate a simple carbon nanotube patterning technique that combines nanotube film bonding, photolithography, and O2 plasma etching. Well defined carbon nanotube film structures with line widths less than ∼1.5μm and thickness ranging from 40to780nm were readily fabricated. A micro-optomechanical actuator based on this process has been demonstrated. This patterning process can be utilized for the integration of nanomaterials for wide variety of devices including microeletromechanical systems, field emission displays, and micro-optomechanical systems (MOMS).

Optically driven actuators have been fabricated from single-wall carbon nanotube-polymer composite sheets. Like natural muscles, the millimetre-scale actuators are assemblies of millions of individual nanotube actuators processed into macroscopic length scales and bonded to an acrylic elastomer sheet to form an actuator that have been shown to generate higher stress than natural muscles and higher strains than high-modulus piezoelectric materials. Strain measurements revealed 0.01%-0.3% elastic strain generated due to electrostatic and thermal effects under visible light intensities of 5-120 mW cm −2. An optically actuated nanotube gripper is demonstrated to show manipulation of small objects. This actuation technology overcomes some of the fundamental limitations such as the use of high voltages or electrochemical solutions for actuation, opening up possibilities for remote light-induced actuation technologies.

No abstract