Search

The field of nanotechnology holds great promise for the diagnosis and treatment of human disease. However, the size and charge of most nanoparticles preclude their efficient clearance from the body as intact nanoparticles. Without such clearance or their biodegradation into biologically benign components, toxicity is potentially amplified and radiological imaging is hindered. Using intravenously administered quantum dots in rodents as a model system, we have precisely defined the requirements for renal filtration and urinary excretion of inorganic, metal-containing nanoparticles. Zwitterionic or neutral organic coatings prevented adsorption of serum proteins, which otherwise increased hydrodynamic diameter by15 nm and prevented renal excretion. A final hydrodynamic diameter5.5 nm resulted in rapid and efficient urinary excretion and elimination of quantum dots from the body. This study provides a foundation for the design and development of biologically targeted nanoparticles for biomedical applications.

We demonstrated a technique to control the placement of 6 nm-diameter CdSe and 5 nm-diameter CdSe/CdZnS colloidal quantum dots (QDs) through electron-beam lithography. This QD-placement technique resulted in an average of three QDs in each cluster, and 87% of the templated sites were occupied by at least one QD. These QD clusters could be in close proximity to one another, with a minimum separation of 12 nm. Photoluminescence measurements of the fabricated QD clusters showed intermittent photoluminescence, which indicates that the QDs were optically active after the fabrication process. This optimized top-down lithographic process is a step towards the integration of individual QDs in optoelectronic and nano-optical systems., Hertz Foundation (Fellowship), United States. Dept. of Energy. Office of Basic Energy Sciences (Award DE-SC0001088)

Bismuth-based compounds have recently gained increasing attention as potentially nontoxic and defect-tolerant solar absorbers. However, many of the new materials recently investigated show limited photovoltaic performance. Herein, one such compound is explored in detail through theory and experiment: bismuth oxyiodide (BiOI). BiOI thin films are grown by chemical vapor transport and found to maintain the same tetragonal phase in ambient air for at least 197 d. The computations suggest BiOI to be tolerant to antisite and vacancy defects. All-inorganic solar cells (ITO|NiO x |BiOI|ZnO|Al) with negligible hysteresis and up to 80% external quantum efficiency under select monochromatic excitation are demonstrated. The short-circuit current densities and power conversion efficiencies under AM 1.5G illumination are nearly double those of previously reported BiOI solar cells, as well as other bismuth halide and chalcohalide photovoltaics recently explored by many groups. Through a detailed loss analysis using optical characterization, photoemission spectroscopy, and device modeling, direction for future improvements in efficiency is provided. This work demonstrates that BiOI, previously considered to be a poor photocatalyst, is promising for photovoltaics., National Science Foundation (U.S.) (Grant CBET-1605495), United States. Department of Energy. Office of Basic Energy Sciences (Grant DE-SC0001088), National Science Foundation (U.S.) (Grant DMF-08019762)

With the emergence of applications based on short-wavelength infrared light, indium arsenide quantum dots are promising candidates to address existing shortcomings of other infrared-emissive nanomaterials. However, III–V quantum dots have historically struggled to match the high-quality optical properties of II–VI quantum dots. Here we present an extensive investigation of the kinetics that govern indium arsenide nanocrystal growth. Based on these insights, we design a synthesis of large indium arsenide quantum dots with narrow emission linewidths. We further synthesize indium arsenide-based core-shell-shell nanocrystals with quantum yields up to 82% and improved photo- and long-term storage stability. We then demonstrate non-invasive through-skull fluorescence imaging of the brain vasculature of murine models, and show that our probes exhibit 2–3 orders of magnitude higher quantum yields than commonly employed infrared emitters across the entire infrared camera sensitivity range. We anticipate that these probes will not only enable new biomedical imaging applications, but also improved infrared nanocrystal-LEDs and photon-upconversion technology., National Science Foundation (U.S.) (EECS-1449291), National Institutes of Health (U.S.) (Massachusetts Institute of Technology. Laser Biomedical Research Center. 9-P41-EB015871-26A1), Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (W911NF-13-D-0001), Boehringer Ingelheim Fonds, European Molecular Biology Organization (Long-term Fellowship), National Science Foundation (U.S.). Graduate Research Fellowship Program, American Society for Engineering Education. National Defense Science and Engineering Graduate Fellowship, United States. Dept. of Energy. Center for Excitonics (DE- SC0001088).

Shape dependent: Fluorescent quantum-dot-based nanospheres and nanorods with identical hydrodynamic size and surface properties but different aspect ratios were developed for real-time in vivo tumor imaging. The nanorods exhibited superior transport and distribution into mammary tumors in vivo versus nanospheres of similar plasma half-life., National Cancer Institute (U.S.) (Grant Number R01-CA126642), MIT-Harvard Center for Cancer Nanotechnology Excellence (1U54-CA119349), Massachusetts Institute of Technology. Dept. of Chemistry Instrumentation Facility (CHE-980806), Massachusetts Institute of Technology. Dept. of Chemistry Instrumentation Facility (DBI-9729592), ISN (W911NF-07-D-0004)

A nanoparticle toolset was created within the size limits of 10–150 nm for probing size-dependent nanoparticle distribution in solid tumors. By using multiphoton intravital microscopy, the particles were tracked both spatially and temporally in the same tumor grown in a transparent window model., National Cancer Institute (U.S.) (Grant R01-CA126642), MIT-Harvard Center for Cancer Nanotechnology Excellence (National Institutes of Health (U.S.) 1U54-CA119349), Massachusetts Institute of Technology. Dept. of Chemistry Instrumentation Facility (CHE-980806), Massachusetts Institute of Technology. Dept. of Chemistry Instrumentation Facility (DBI-9729592), Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (W911NF-07-D-0004), National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (DMR-0117795), National Science Foundation (U.S.). Climate Research Division (CHE-0714189), National Science Foundation (U.S.). Graduate Research Fellowship Program, Novartis Foundation (Fellow of the Life Sciences Research Foundation)

Inorganic/organic hybrid nanoparticles are potentially useful in biomedicine, but to avoid non-specific background fluorescence and long-term toxicity, they need to be cleared from the body within a reasonable timescale1. Previously, we have shown that rigid spherical nanoparticles such as quantum dots can be cleared by the kidneys if they have a hydrodynamic diameter of approximately 5.5 nm and a zwitterionic surface charge2. Here, we show that quantum dots functionalized with high-affinity small-molecule ligands that target tumours can also be cleared by the kidneys if their hydrodynamic diameter is less than this value, which sets an upper limit of 5–10 ligands per quantum dot for renal clearance. Animal models of prostate cancer and melanoma show receptor-specific imaging and renal clearance within 4 h post-injection. This study suggests a set of design rules for the clinical translation of targeted nanoparticles that can be eliminated through the kidneys., National Science Foundation (U.S.) (NSF-0070319), National Institutes of Health (U.S.) (NIH GM68762), National Institutes of Health (U.S.) (NIH grant no. R33-EB-000673), National Institutes of Health (U.S.) ( NIH grant no. R01-CA-115296), National Institutes of Health (U.S.) (MIT-Harvard NanoMedical Consortium (1U54-CA119349, a Center of Cancer Nanotechnology Excellence)), Bank of America, Medical Foundation, inc. (Charles A. King Trust Postdoctoral Research Fellowship Program), cancer

Magneto-fluorescent particles have been recognized as an emerging class of materials that exhibit great potential in advanced applications. However, synthesizing such magneto-fluorescent nanomaterials that simultaneously exhibit uniform and tunable sizes, high magnetic content loading, maximized fluorophore coverage at the surface and a versatile surface functionality has proven challenging. Here we report a simple approach for co-assembling magnetic nanoparticles with fluorescent quantum dots to form colloidal magneto-fluorescent supernanoparticles. Importantly, these supernanoparticles exhibit a superstructure consisting of a close-packed magnetic nanoparticle ‘core’, which is fully surrounded by a ‘shell’ of fluorescent quantum dots. A thin layer of ​silica coating provides high colloidal stability and biocompatibility, and a versatile surface functionality. We demonstrate that after surface pegylation, these ​silica-coated magneto-fluorescent supernanoparticles can be magnetically manipulated inside living cells while being optically tracked. Moreover, our ​silica-coated magneto-fluorescent supernanoparticles can also serve as an in vivo multi-photon and magnetic resonance dual-modal imaging probe., National Institutes of Health (U.S.) (5-U54-CA151884), National Institutes of Health (U.S.) (R01-CA126642), Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (W911NF-13-D-0001)), United States. Dept. of Energy (DE-FG02-07ER46454), National Institutes of Health (U.S.) (Massachusetts Institute of Technology. Laser Biomedical Research Center 9-P41-EB015871-26A1), United States. Dept. of Energy. Office of Basic Energy Sciences (Award DE-SC0001088), United States. Dept. of Defense (Breast Cancer Research Innovator Award W81XWH-10-1-0016)), Human Frontier Science Program (Strasbourg, France) (Grant RGP0005/2007), National Institutes of Health (U.S.) (R01-DA028299), National Institutes of Health (U.S.) (R01-NS076462), European Molecular Biology Organization (Long-term Fellowship)

Height time hyperspectral near IR probing providing broad-band coverage is employed on PbSe nanocrystals, uncovering spectral evolution following high energy photo-excitation due to hot exciton relaxation and recombination. Separation of single, double and triple exciton state contributions to these spectra is demonstrated, and the mechanisms underlying the course of spectral evolution are investigated. In addition no sign of MEG was detected in this sample up to a photon energy 3.7 times that of the band gap.