Xin Wang

Bio: Xin Wang is an academic researcher from Peking University. The author has contributed to research in topics: Medicine & Chemistry. The author has an hindex of 59, co-authored 762 publications receiving 22731 citations. Previous affiliations of Xin Wang include Beihang University & Sichuan University.

Quantum-sized carbon dots for bright and colorful photoluminescence.

Abstract: We report that nanoscale carbon particles (carbon dots) upon simple surface passivation are strongly photoluminescent in both solution and the solid state. The luminescence emission of the carbon dots is stable against photobleaching, and there is no blinking effect. These strongly emissive carbon dots may find applications similar to or beyond those of their widely pursued silicon counterparts.

Carbon dots for multiphoton bioimaging

Abstract: Carbon nanoparticles upon simple surface passivation exhibit bright photoluminescence. Reported here is a new finding that these carbon dots are also strongly two-photon luminescent with pulsed laser excitation in the near-infrared. The experimentally measured two-photon absorption cross-sections are comparable to those of the high-performance semiconductor quantum dots already available in the literature. The two-photon luminescence microscopy imaging of human breast cancer cells with internalized carbon dots is demonstrated.

Carbon dots for optical imaging in vivo.

Abstract: It was found and recently reported that small carbon nanoparticles can be surface-passivated by organic or biomolecules to become strongly fluorescent. These fluorescent carbon nanoparticles, dubbed “carbon dots”, can be successfully used for in vitro cell imaging with both one- and two-photon excitations, as already demonstrated in the literature. Here we report the first study using carbon dots for optical imaging in live mice. The results suggest that the carbon dots remain strongly fluorescent in vivo, which, coupled with their biocompatibility and nontoxic characteristics, might offer great potential for imaging and related biomedical applications.

Carbon Dots as Nontoxic and High-Performance Fluorescence Imaging Agents

Abstract: Fluorescent carbon dots (small carbon nanoparticles with the surface passivated by oligomeric PEG molecules) were evaluated for their cytotoxicity and in vivo toxicity and also for their optical imaging performance in reference to that of the commercially supplied CdSe/ZnS quantum dots. The results suggested that the carbon dots were biocompatible, and their performance as fluorescence imaging agents was competitive. The implication to the use of carbon dots for in vitro and in vivo applications is discussed.

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Thermal properties of graphene and nanostructured carbon materials

Abstract: Recent years have seen a rapid growth of interest by the scientific and engineering communities in the thermal properties of materials. Heat removal has become a crucial issue for continuing progress in the electronic industry, and thermal conduction in low-dimensional structures has revealed truly intriguing features. Carbon allotropes and their derivatives occupy a unique place in terms of their ability to conduct heat. The room-temperature thermal conductivity of carbon materials span an extraordinary large range--of over five orders of magnitude--from the lowest in amorphous carbons to the highest in graphene and carbon nanotubes. Here, I review the thermal properties of carbon materials focusing on recent results for graphene, carbon nanotubes and nanostructured carbon materials with different degrees of disorder. Special attention is given to the unusual size dependence of heat conduction in two-dimensional crystals and, specifically, in graphene. I also describe the prospects of applications of graphene and carbon materials for thermal management of electronics.

Luminescent Carbon Nanodots: Emergent Nanolights

Abstract: Similar to its popular older cousins the fullerene, the carbon nanotube, and graphene, the latest form of nanocarbon, the carbon nanodot, is inspiring intensive research efforts in its own right. These surface-passivated carbonaceous quantum dots, so-called C-dots, combine several favorable attributes of traditional semiconductor-based quantum dots (namely, size- and wavelength-dependent luminescence emission, resistance to photobleaching, ease of bioconjugation) without incurring the burden of intrinsic toxicity or elemental scarcity and without the need for stringent, intricate, tedious, costly, or inefficient preparation steps. C-dots can be produced inexpensively and on a large scale (frequently using a one-step pathway and potentially from biomass waste-derived sources) by many approaches, ranging from simple candle burning to in situ dehydration reactions to laser ablation methods. In this Review, we summarize recent advances in the synthesis and characterization of C-dots. We also speculate on their future and discuss potential developments for their use in energy conversion/storage, bioimaging, drug delivery, sensors, diagnostics, and composites.