Recent years have witnessed many breakthroughs in research on graphene (the first two-dimensional atomic crystal) as well as a significant advance in the mass production of this material. This one-atom-thick fabric of carbon uniquely combines extreme mechanical strength, exceptionally high electronic and thermal conductivities, impermeability to gases, as well as many other supreme properties, all of which make it highly attractive for numerous applications. Here we review recent progress in graphene research and in the development of production methods, and critically analyse the feasibility of various graphene applications.

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A roadmap for graphene

Nanotechnology has the potential to revolutionize cancer diagnosis and therapy. Advances in protein engineering and materials science have contributed to novel nanoscale targeting approaches that may bring new hope to cancer patients. Several therapeutic nanocarriers have been approved for clinical use. However, to date, there are only a few clinically approved nanocarriers that incorporate molecules to selectively bind and target cancer cells. This review examines some of the approved formulations and discusses the challenges in translating basic research to the clinic. We detail the arsenal of nanocarriers and molecules available for selective tumour targeting, and emphasize the challenges in cancer treatment.

Nanocarriers as an emerging platform for cancer therapy

Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. Our aim is to present a comprehensive review of current research activities that center on the shape-controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution-phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Finally, we highlight a number of applications that have been enabled and/or enhanced by the shape-controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take.

Shape‐Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets Complex Physics?

We investigated the intracellular uptake of different sized and shaped colloidal gold nanoparticles. We showed that kinetics and saturation concentrations are highly dependent upon the physical dimensions of the nanoparticles (e.g., uptake half-life of 14, 50, and 74 nm nanoparticles is 2.10, 1.90, and 2.24 h, respectively). The findings from this study will have implications in the chemical design of nanostructures for biomedical applications (e.g., tuning intracellular delivery rates and amounts by nanoscale dimensions and engineering complex, multifunctional nanostructures for imaging and therapeutics).

Determining the size and shape dependence of gold nanoparticle uptake into mammalian cells.

The selection of nanoparticles for achieving efficient contrast for biological and cell imaging applications, as well as for photothermal therapeutic applications, is based on the optical properties of the nanoparticles. We use Mie theory and discrete dipole approximation method to calculate absorption and scattering efficiencies and optical resonance wavelengths for three commonly used classes of nanoparticles:  gold nanospheres, silica−gold nanoshells, and gold nanorods. The calculated spectra clearly reflect the well-known dependence of nanoparticle optical properties viz. the resonance wavelength, the extinction cross-section, and the ratio of scattering to absorption, on the nanoparticle dimensions. A systematic quantitative study of the various trends is presented. By increasing the size of gold nanospheres from 20 to 80 nm, the magnitude of extinction as well as the relative contribution of scattering to the extinction rapidly increases. Gold nanospheres in the size range commonly employed (∼40 nm)...

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Calculated Absorption and Scattering Properties of Gold Nanoparticles of Different Size, Shape, and Composition: Applications in Biological Imaging and Biomedicine

The present invention is directed to a method for real-time characterization of spatially-resolved tissue optical properties using OCT/LCI. Imaging data are acquired, processed, displayed and stored in real-time. The resultant tissue optical properties are then used to determine the diagnostic threshold and to determine the OCT/LCI detection sensitivity and specificity. Color-coded optical property maps are constructed to provide direct visual cues for surgeons to differentiate tumor versus non-tumor tissue. These optical property maps can be overlaid with the structural imaging data and/or Doppler results for efficient data display. Finally, the imaging system can also be integrated with existing systems such as tracking and surgical microscopes. An aiming beam is generally provided for interventional guidance. For intraoperative use, a cap/spacer may also be provided to maintain the working distance of the probe, and also to provide biopsy capabilities. The method is usable for research and clinical diagnosis and/or interventional guidance.

Quantitative tissue property mapping for real time tumor detection and interventional guidance

In this presentation, the application of optical coherence tomography (OCT) to the prevention of myocardial infarction and early identification of osteoarthritis is discussed. Myocardial infarction or a heart attack is the leading cause of death worldwide. It results from an acute loss of blood flow to a region of the heart resulting in death to that heart tissue. Most heart attacks are caused by small, thin walled lipid filled plaques which can not be detected by currently available imaging technologies. This paper outlines some of the advances demonstrating the potential of OCT for the identification of high risk plaque. Osteoarthritis is a major cause of mobility in the industrialized world. The hallmark of the disease is a degradation of articular cartilage. As new therapeutics have been shown to be effective in animal models, there effectiveness in humans remains unclear as there is no effective method for accurate monitoring changes in cartilage. In the second part of this manuscript, the effectiveness of OCT for monitoring articular cartilage is described.

OCT imaging of the musculoskeletal and cardiovascular systems

A true clinical need exists for a high resolution imaging modality to characterize coronary microstructure. In this study, OCT imaging was performed of the in in vivo rabbit aorta examining clot, atherosclerosis, and intravascular stents. The performance of OCT was superior to that of high frequency ultrasound.

In Vivo Intravascular Imaging with OCT: Comparison with Ultrasound

Optical coherence tomography (OCT) enables imaging of tissue pathology in situ and in real time. Using ultrashort pulse lasers, ultrahigh resolutions of -1 μm as well as spectroscopic imaging are possible. OCT can function as a type of optical biopsy because it enables imaging tissue microstructure in situ without the need to excise and process a specimen as in conventional histopathology. OCT can be used to image pathology in tissues where biopsy is impossible.

Optical Coherence Tomography for Biomedical Imaging

We present a flexible fiber-optic scanning endoscope for two-photon fluorescence imaging and demonstrate it on live cells. Two-dimensional beam scanning at kilohertz frequencies was achieved using a PZT tube to actuate a double-clad fiber.

Xingde Li

Papers

Quantitative tissue property mapping for real time tumor detection and interventional guidance

OCT imaging of the musculoskeletal and cardiovascular systems

In Vivo Intravascular Imaging with OCT: Comparison with Ultrasound

Optical Coherence Tomography for Biomedical Imaging

Two-photon Fiber-optic Scanning Endoscope