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

We presented a new OCT endoscope design for ultrahigh-resolution 3D imaging at 800nm by using a diffractive microlens for chromatic aberration management. The performance of the OCT imaging catheter was demonstrated by in vivo experiments

Diffractive Endoscope for Real-time Ultrahigh-resolution Volumetric OCT Imaging at 800 nm

Label-Free Metabolic Imaging in vivo by Two-Photon Fluorescence Lifetime Endomicroscopy

We present recent updates on our work on developing a fully integrated, miniaturized fiber-optic scanning endomicroscope for performing nonlinear optical imaging including two-photon fluorescence and second harmonic generation. We describe our design approaches for significantly improving signal collection efficiency and resolution. Preliminary tissue imaging results will be presented to demonstrate the potential of the nonlinear endomicroscopy technology for diagnostics and image-based guidance.

Nonlinear optical imaging with a scanning fiber-optic endomicroscope

Multiphoton fluorescence imaging allows clinicians to identify early signs of oral cancer at its origin below the tissue surface. The high resolution required for adequate morphological assessment is only possible over a relatively small field of view, however, so an additional co-registered wide field of view, low resolution image is crucial for efficient device operation. To meet this need, we present the design of a handheld intraoral probe that includes a 0.50NA objective for multiphoton imaging and auxiliary cameras for region-of-interest identification. Because multiphoton image quality is most dependent on the high NA objective, we characterize its performance and correlate findings to expected system-level quality. Finally, we show concepts for the design and manufacturing strategy of a compact, monolithic, high NA freeform prism objective optimized for multiphoton imaging in the oral cavity. 

Design and characterization of handheld multiphoton probe for intraoral imaging (Conference Presentation)

Summary form only given. In this study, intraoperative imaging was performed to investigate the feasibility of OCT for imaging prostate pathology in vivo as well as to investigate OCT intraoperative imaging in a more general context. A sterilizable hand-held surgical probe was developed and used with a portable OCT system to image in the surgical suite and pathology laboratory. The imaging probe has a 2 cm working distance which allows the surgeon to maneuver the beam within the tight confines of the surgical field. Preliminary results demonstrate the feasibility of intraoperative OCT imaging in human subjects as well as imaging in a pathology laboratory environment.

Xingde Li

Papers

Diffractive Endoscope for Real-time Ultrahigh-resolution Volumetric OCT Imaging at 800 nm

Label-Free Metabolic Imaging in vivo by Two-Photon Fluorescence Lifetime Endomicroscopy

Nonlinear optical imaging with a scanning fiber-optic endomicroscope

Design and characterization of handheld multiphoton probe for intraoral imaging (Conference Presentation)

Intraoperative imaging using optical coherence tomography