Shaoxin Lu

Integrated molecular targeting of IGF1R and HER2 surface receptors and destruction of breast cancer cells using single wall carbon nanotubes

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.

Optically driven nanotube actuators

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.

Nanotube micro-optomechanical actuators

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).

Photomechanical responses of carbon nanotube/polymer actuators

Recent studies have investigated the photomechanical properties of carbon nanotubes which can be utilized to construct optical actuators. In this paper we compare the photomechanical response from single-wall and multi-wall carbon nanotube/polymer systems in multilayer and nanocomposite actuator constructions. Incorporating polymers in the actuators, single-wall and multi-wall nanotubes show similar photomechanical responses, which are directly related to prestrain and nanotube alignments. Nanotube/polymer multilayered actuators exhibit comparable actuation strokes to the nanocomposite counterparts, while enabling easier sample construction, intact polymer and nanotube properties, and compatibility to CMOS/MEMS processes. The photomechanical responses can be well understood based on affine modelling of photomechanical responses.

Single-wall carbon nanotube nanobomb agents for killing breast cancer cells

We report the first application of single-wall carbon nanotubes (SWCNT) as potent therapeutic nanobomb agents for killing breast cancer cells. We show here that by adsorbing water molecules in SWCNT sheets or loosely adsorbed on top of cells, potent nanobombs were created that heated the water molecules inside them to more than 100°C upon exposure to laser light of 800 nm at light intensities of approx 50–200 mW/cm2. Conversion of optical energy into thermal energy, and the subsequent confinement of thermal energy in SWCNT, caused the water molecules to evaporate and develop extreme pressures in SWCNT causing them to explode in solutions. Co-localized nanobombs killed human BT474 breast cancer cells in physiological phosphate-buffered saline (PBS) solution. Cells that were treated with nanobombs exploded into fragments, while the surrounding cells not treated with nanobombs were viable. SWCNT-based nanobomb agents can potentially outperform most nanotechnological approaches in killing cancer cells without toxicity.

Alignment dependent mechanical responses of carbon nanotubes to light

The authors report the orientation dependent elastic responses of carbon nanotubes to infrared photons. Unaligned and partially aligned samples of single wall carbon nanotubes (SWCNTs) and multiwall carbon nanotubes (MWCNTs) were studied for orientation dependent mechanical responses. While partial alignment in MWCNT ensembles changed the mechanical response to photons from expansion to contraction, the speeds of photomechanical responses were increased at least an order of magnitude by nanotube partial alignment in both SWCNT and MCWNT samples. The unique alignment dependent reversible photomechanical responses of carbon nanotubes are critical for actuator applications.

A Platinum Nanowires Actuator: Metallic Nano-Muscles

In this paper, we report the fabrication and characterization of electro-chemical actuator using platinum nanowire networks. Reversible strain amplitudes of ~ 0.04% have been observed by controlling the surface electronic charge density of the nanowire network through an applied voltage in an electrolyte solution. Displacement amplitudes of up to 3mm was observed for an applied voltage of only ±3 V, much smaller compared to most commercial piezoceramic materials. These results indicate the potential application of platinum nanowires for construction of artificial muscles and materials with tunable electronic properties.

Nanotube Micro-Opto-Mechanical Systems (N-MOMS)

In this paper we report the first applications of single wall carbon nanotube based micro-optomechanical systems (MOMS). Thin films of nanotubes with line widths ranging less than 1.5 mum and thicknesses ranging from 40 to 700 nm were patterned into micro-mechanical systems using batch fabrication techniques. Arrays of nanotube based MOM actuators, MOM-micromirrors and MOM-micro-grippers were fabricated using CMOS compatible techniques. Nanotube based MOMS devices showed better performance compared to their MEMS based electrostatic silicon counterparts and consumed only 200 muW-170 mW of power. These studies open a new field of nanotube based MOMS that could potentially outperform silicon based MEMS devices.

Metallic Nanowires From Carbon Nanotube Building Blocks: The Effect of Atomic Defects on the Nanotube Influencing Nanowire Growth

Manipulation and control of matter at the nano- and atomic level are crucial for the success of nano-scale sensors and actuators. The ability to control and synthesize multilayer structures using carbon nanotubes that will enable to build electronic devices within a nanotube is still in its infancy. In this paper, we present results on selective electric field assisted deposition of metals on carbon nanotubes realizing metallic nanowire structures. Silver and platinum nanowires has been fabricated using this approach due to its applications in chemical sensing sensing as catalytic materials to sniff toxic agents and in the area of biomedical nanotechnology for construction of artificial muscles. The electric field assisted technique allows the deposition of metals with high degree of selectivity on carbon nanotubes by manipulating the charges on the surface of the nanotubes. The thickness and the growth of the nanowires was altered by inducing defects on the initial surface of the nanotubes that affected the local current densities and electrochemical reduction of silver and platinum on those defect sites. SEM and TEM investigations revealed silver and platinum nanowires between 10 nm-100 nm in diameter. Relatively higher metal deposition was achieved in defect related sites or places where the nanotubes criss-crossed each other, due to the high current densities in these sites. The present technique is versatile and enables the fabrication of host of different types of metallic and semiconduting nanowires using carbon nanotube templates for nanoelectronics and myriad of sensor applications. Further, nanowires can also serve as model systems for studying quantum size effects in these dimensions.Copyright