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A simple, reliable, and cost-effective experiment is presented in which students synthesized citrate-capped gold nanoparticles (GNPs), functionalized them with poly(ethylene glycol) (PEG), and transferred the PEG-GNPs from water to the organic phase dichloromethane. The experiment introduces students to nanotechnology with foci on important concepts including surface modification of nanoparticles, colloidal stability, and phase transfer. The proposed experiment was evaluated at three different universities to confirm its reproducibility and versatility. Collectively, the proposed experiment is suitable to be implemented into colloid- or nanoscience-related curricula.

DC-SIGN, a Ca(2+)-dependent transmembrane lectin, is found assembled in microdomains on the plasma membranes of dendritic cells. These microdomains bind a large variety of pathogens and facilitate their uptake for subsequent antigen presentation. In this study, DC-SIGN dynamics in microdomains were explored with several fluorescence microscopy methods and compared with dynamics for influenza hemagglutinin (HA), which is also found in plasma membrane microdomains. Fluorescence imaging indicated that DC-SIGN microdomains may contain other C-type lectins and that the DC-SIGN cytoplasmic region is not required for microdomain formation. Fluorescence recovery after photobleaching measurements showed that neither full-length nor cytoplasmically truncated DC-SIGN in microdomains appreciably exchanged with like molecules in other microdomains and the membrane surround, whereas HA in microdomains exchanged almost completely. Line-scan fluorescence correlation spectroscopy indicated an essentially undetectable lateral mobility for DC-SIGN but an appreciable mobility for HA within their respective domains. Single-particle tracking with defined-valency quantum dots confirmed that HA has significant mobility within microdomains, whereas DC-SIGN does not. By contrast, fluorescence recovery after photobleaching indicated that inner leaflet lipids are able to move through DC-SIGN microdomains. The surprising stability of DC-SIGN microdomains may reflect structural features that enhance pathogen uptake either by providing high-avidity platforms and/or by protecting against rapid microdomain endocytosis.

CuBi2O4 has recently emerged as a promising photocathode for photo‐electrochemical (PEC) water splitting. However, its fast degradation under operation currently poses a limit to its application. Here, we report a novel method to study operando the semiconductor‐electrolyte interface during PEC operation by surface‐sensitive high‐energy X‐ray scattering. We find that a fast decrease in the generated photocurrents correlates directly with the formation of a metallic Bi phase. We further show that the slower formation of metallic Cu, as well as the dissolution of the electrode in contact with the electrolyte, further affect the CuBi2O4 activity and morphology. Our study provides a comprehensive picture of the degradation mechanisms affecting CuBi2O4 electrodes under operation and poses the methodological basis to investigate the photocorrosion processes affecting a wide range of PEC materials. [ABSTRACT FROM AUTHOR]

Rare earth based nanostructures constitute a type of functional materials widely used and studied in the recent literature. The purpose of this review is to provide a general and comprehensive overview of the current state of the art, with special focus on the commonly employed synthesis methods and functionalization strategies of rare earth based nanoparticles and on their different bioimaging and biosensing applications. The luminescent (including downconversion, upconversion and permanent luminescence) and magnetic properties of rare earth based nanoparticles, as well as their ability to absorb X-rays, will also be explained and connected with their luminescent, magnetic resonance and X-ray computed tomography bioimaging applications, respectively. This review is not only restricted to nanoparticles, and recent advances reported for in other nanostructures containing rare earths, such as metal organic frameworks and lanthanide complexes conjugated with biological structures, will also be commented on.

Semiconductor nanocrystals with narrow and tunable fluorescence are covalently linked to oligonucleotides. These biocompounds retain the properties of both nanocrystals and DNA. Therefore, different sequences of DNA can be coded with nanocrystals and still preserve their ability to hybridize to their complements. We report the case where four different sequences of DNA are linked to four nanocrystal samples having different colors of emission in the range of 530-640 nm. When the DNA-nanocrystal conjugates are mixed together, it is possible to sort each type of nanoparticle using hybridization on a defined micrometer -size surface containing the complementary oligonucleotide. Detection of sorting requires only a single excitation source and an epifluorescence microscope. The possibility of directing fluorescent nanocrystals towards specific biological targets and detecting them, combined with their superior photo-stability compared to organic dyes, opens the way to improved biolabeling experiments, such as gene mapping on a nanometer scale or multicolor microarray analysis.

Water-soluble, highly fluorescent, silanized semiconductor nanocrystals with different surface charges were synthesized. To covalently attach the nanocrystals to biological macromolecules with a variety of mild coupling chemistries, the outermost siloxane shells were derivatized with thiol, amino, or carboxyl functional groups. Single- or double-stranded DNA was coupled to the nanocrystal surfaces by using commercially available bifunctional cross-linker. Conjugation had little effect on the optical properties of the nanocrystals, and the resulting conjugates were more stable than previously reported systems. By using the strategies developed in this study, most biomolecules can be covalently coupled to semiconductor nanocrystals. These nanocrystal-DNA conjugates promise to be a versatile tool for fluorescence imaging and probing of biological systems.

In recent years, much effort has been invested into developing multifunctional drug delivery systems to overcome the drawbacks of conventional carriers. Magnetic nanoparticles are not generally used as carriers but can be functionalised with several different biomolecules and their size can be tailored to present a hyperthermia response, allowing for the design of multifunctional systems which can be active in therapies. In this work, we have designed a drug carrier nanosystem based on Fe3O4 nanoparticles with large heating power and 4-amino-2-pentylselenoquinazoline as an attached drug that exhibits oxidative properties and high selectivity against a variety of cancer malignant cells. For this propose, two samples composed of homogeneous Fe3O4 nanoparticles (NPs) with different sizes, shapes, and magnetic properties have been synthesised and characterised. The surface modification of the prepared Fe3O4 nanoparticles has been developed using copolymers composed of poly(ethylene-alt-maleic anhydride), dodecylamine, polyethylene glycol and the drug 4-amino-2-pentylselenoquinazoline. The obtained nanosystems were properly characterised. Their in vitro efficacy in colon cancer cells and as magnetic hyperthermia inductors was analysed, thereby leaving the door open for their potential application as multimodal agents. [ABSTRACT FROM AUTHOR]