Quantitative and reversible lectin-induced association of gold nanoparticles modified with alpha-lactosyl-omega-mercapto-poly(ethylene glycol)

Glyconanoparticles for colorimetric bioassays

Carbohydrate molecules are involved in many of the cellular processes that are important for life. By combining the specific analyte targeting of carbohydrates with the multivalent structure and change of solution colour as a consequence of plasmonic interactions with the aggregation of metal nanoparticles, glyconanoparticles have been used extensively for the development of bioanalytical assays. The noble metals used to create the nanocore, the methodologies used to assemble the carbohydrates on the nanoparticle surface, the carbohydrate chosen for each specific target, the length of the tether that separates the carbohydrate from the nanocore and the density of carbohydrates on the surface all impact on the structural formation of metal based glyconanoparticles. This tutorial review highlights these key components, which directly impact on the selectivity and sensitivity of the developed bioassay, for the colorimetric detection of lectins, toxins and viruses.

Probing cell-surface carbohydrate binding proteins with dual-modal glycan-conjugated nanoparticles

Dual-modal fluorescent magnetic glyconanoparticles have been prepared and shown to be powerful in probing lectins displayed on pathogenic and mammalian cell surfaces. Blood group H1- and Le(b)-conjugated nanoparticles were found to bind to BabA displaying Helicobacter pylori, and Le(a)- and Le(b)-modified nanoparticles are both recognized by and internalized into DC-SIGN and SIGN-R1 expressing mammalian cells via lectin-mediated endocytosis. In addition, glyconanoparticles block adhesion of H. pylori to mammalian cells, suggesting that they can serve as inhibitors of infection of host cells by this pathogen. It has been also shown that owing to their magnetic properties, glyconanoparticles are useful tools to enrich lectin expressing cells. The combined results indicate that dual-modal glyconanoparticles are biocompatible and that they can be employed in lectin-associated biological studies and biomedical applications.

Multi-functional self-fluorescent unimolecular micelles for tumor-targeted drug delivery and bioimaging

A novel type of self-fluorescent unimolecular micelle nanoparticle (NP) formed by multi-arm star amphiphilic block copolymer, Boltron® H40 (H40, a 4th generation hyperbranched polymer)-biodegradable photo-luminescent polymer (BPLP)-poly(ethylene glycol) (PEG) conjugated with cRGD peptide (i.e., H40-BPLP-PEG-cRGD) was designed, synthesized, and characterized. The hydrophobic BPLP segment was self-fluorescent, thereby making the unimolecular micelle NP self-fluorescent. cRGD peptides, which can effectively target αvβ3 integrin-expressing tumor neovasculature and tumor cells, were selectively conjugated onto the surface of the micelles to offer active tumor-targeting ability. This unique self-fluorescent unimolecular micelle exhibited excellent photostability and low cytotoxicity, making it an attractive bioimaging probe for NP tracking for a variety of microscopy techniques including fluorescent microscopy, confocal laser scanning microscopy (CLSM), and two-photon microscopy. Moreover, this self-fluorescent unimolecular micelle NP also demonstrated excellent stability in aqueous solutions due to its covalent nature, high drug loading level, pH-controlled drug release, and passive and active tumor-targeting abilities, thereby making it a promising nanoplatform for targeted cancer theranostics.

Novel bio-friendly and non-toxic thiocarbohydrate stabilizers of gold nanoparticles

A new class of stabilizers for gold nanoparticles has been develop with non-toxic thiocarbohydrates that were prepared from d-(+)-gluconic acid δ-lactone and aminoalkylthiols.

Seeing diabetes: visual detection of glucose based on the intrinsic peroxidase-like activity of MoS2 nanosheets

Molybdenum disulfide (MoS2) has attracted increasing research interest recently due to its unique physical, optical and electrical properties, correlated with its 2D ultrathin atomic-layered structure. Until now, however, great efforts have focused on its applications such as lithium ion batteries, transistors, and hydrogen evolution reactions. Herein, for the first time, MoS2 nanosheets are discovered to possess an intrinsic peroxidase-like activity and can catalytically oxidize 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to produce a color reaction. The catalytic activity follows the typical Michaelis-Menten kinetics and is dependent on temperature, pH, H2O2 concentration, and reaction time. Based on this finding, a highly sensitive and selective colorimetric method for H2O2 and glucose detection is developed and applied to detect glucose in serum samples. Moreover, a simple, inexpensive, instrument-free and portable test kit for the visual detection of glucose in normal and diabetic serum samples is constructed by utilizing agarose hydrogel as a visual detection platform.

Glyconanomaterials: Emerging applications in biomedical research

Carbohydrates constitute the most abundant organic matter in nature, serving as structural components and energy sources, and mediating a wide range of cellular activities. The emergence of nanomaterials with distinct optical, magnetic, and electronic properties has witnessed a rapid adoption of these materials for biomedical research and applications. Nanomaterials of various shapes and sizes having large specific surface areas can be used as multivalent scaffolds to present carbohydrate ligands. The resulting glyconanomaterials effectively amplify the glycan-mediated interactions, making it possible to use these materials for sensing, imaging, diagnosis, and therapy. In this review, we summarize the synthetic strategies for the preparation of various glyconanomaterials. Examples are given where these glyconanomaterials have been used in sensing and differentiation of proteins and cells, as well as in imaging glycan-medicated cellular responses.

Distinct Rayleigh scattering from hot spot mutant p53 proteins reveals cancer cells

The scattering of light redirects and resonances when an electromagnetic wave interacts with electrons orbits in the hot spot core protein and oscillated electron of the gold nanoparticles (AuNP). This report demonstrates convincingly that resonant Rayleigh scattering generated from hot spot mutant p53 proteins is correspondence to cancer cells. Hot spot mutants have unique local electron density changes that affect specificity of DNA binding affinity compared with wild types. Rayleigh scattering changes introduced by hot-spot mutations were monitored by localized surface plasmon resonance (LSPR) shift changes. The LSPR λmax shift for hot-spot mutants ranged from 1.7 to 4.2 nm for mouse samples and from 0.64 nm to 2.66 nm for human samples, compared to 9.6 nm and 15 nm for wild type and mouse and human proteins, respectively with a detection sensitivity of p53 concentration at 17.9 nM. It is interesting that hot-spot mutants, which affect only interaction with DNA, launches affinitive changes as considerable as wild types. These changes propose that hot-spot mutants p53 proteins can be easily detected by local electron density alterations that disturbs the specificity of DNA binding of p53 core domain on the surface of the DNA probed-nanoplasmonic sensor.

DNA sensors and aptasensors based on the hemin/G-quadruplex-controlled aggregation of Au NPs in the presence of L-cysteine

L-cysteine induces the aggregation of Au nanoparticles (NPs), resulting in a color transition from red to blue due to interparticle plasmonic coupling in the aggregated structure. The hemin/G-quadruplex horseradish peroxidase-mimicking DNAzyme catalyzes the aerobic oxidation of L-cysteine to cystine, a process that inhibits the aggregation of the NPs. The degree of inhibition of the aggregation process is controlled by the concentration of the DNAzyme in the system. These functions are implemented to develop sensing platforms for the detection of a target DNA, for the analysis of aptamer-substrate complexes, and for the analysis of L-cysteine in human urine samples. A hairpin DNA structure that includes a recognition site for the DNA analyte and a caged G-quadruplex sequence, is opened in the presence of the target DNA. The resulting self-assembled hemin/G-quadruplex acts as catalyst that controls the aggregation of the Au NPs. Also, the thrombin-binding aptamer folds into a G-quadruplex nanostructure upon binding to thrombin. The association of hemin to the resulting G-quadruplex aptamer-thrombin complex leads to a catalytic label that controls the L-cysteine-mediated aggregation of the Au NPs. The hemin/G-qaudruplex-controlled aggregation of Au NPs process is further implemented for visual and spectroscopic detection of L-cysteine concentration in urine samples.

Revisiting 30 years of biofunctionalization and surface chemistry of inorganic nanoparticles for nanomedicine

In the last 30 years we have assisted to a massive advance of nanomaterials in material science. Nanomaterials and structures, in addition to their small size, have properties that differ from those of larger bulk materials, making them ideal for a host of novel applications. The spread of nanotechnology in the last years has been due to the improvement of synthesis and characterization methods on the nanoscale, a field rich in new physical phenomena and synthetic opportunities. In fact, the development of functional nanoparticles has progressed exponentially over the past two decades. This work aims to extensively review 30 years of different strategies of surface modification and functionalization of noble metal (gold) nanoparticles, magnetic nanocrystals and semiconductor nanoparticles, such as quantum dots. The aim of this review is not only to provide in-depth insights into the different biofunctionalization and characterization methods, but also to give an overview of possibilities and limitations of the available nanoparticles.

Fluorescence imaging enabled biodegradable photostable polymeric micelles

Amphiphilic biodegradable photoluminescent polymers (ABPLPs) composed of a biodegradable fluorescent polymer and methoxy poly (ethyleneglycol) demonstrate intrinsic bright, tunable, and stable fluorescence emission. ABPLP micelles elicit minor cellular toxicity and can be used for cell and tissue imaging both in vitro and in vivo.

β-Cyclodextrin-bearing gold glyconanoparticles for the development of site specific drug delivery systems

Three novel gold nanoparticles containing multiple long, flexible linkers decorated with lactose, β-cyclodextrin, and both simultaneously have been prepared. The interaction of such nanoparticles with β-d-galactose-recognizing lectins peanut agglutinin (PNA) and human galectin-3 (Gal-3) was demonstrated by UV-vis studies. Gal-3 is well-known to be overexpressed in several human tumors and can act as a biorecognizable target. This technique also allowed us to estimate their loading capability toward the anticancer drug methotrexate (MTX). Both results make these glyconanoparticles potential site-specific delivery systems for anticancer drugs.

A tailor-made nucleoside-based colourimetric probe of formic acid

A ratiometric, specific probe of formic acid has been developed.

T7 bacteriophage induced changes of gold nanoparticle morphology: biopolymer capped gold nanoparticles as versatile probes for sensitive plasmonic biosensors

The morphological changes of gold nanoparticles induced by T7 virus (bacteriophage) and the determination of its femtomolar concentration by a plasmonic method are presented.

Multivalent glycosylated nanoparticles for studying carbohydrate–protein interactions

Glyconanoparticles decorated with multiple copies of various biologically relevant carbohydrates serve as scaffolds for protein binding assay, molecular imaging, targeted therapy, and bacterium detection.

Localized surface plasmon resonance: a unique property of plasmonic nanoparticles for nucleic acid detection

Localized surface plasmon resonance (LSPR) of noble metal nanoparticles (a.k.a. plasmonic nanoparticles) opens up a new horizon for advanced biomolecule sensing. However, an effective and practical sensing system still requires meticulous design to achieve good sensitivity and distinctive selectivity for routine use and high-throughput detection. In particular, the detection of DNA and RNA is crucial in biomedical research and clinical diagnostics. This review describes the fundamental aspects of LSPR and provides an overall account of how it is exploited to assist in nucleic acid sensing. The detection efficiency of each LSPR-based approach is assessed with respect to the assay design, the selection of plasmonic nanoparticles, and the choice of nucleic acid probes which influence the duplex hybridization. Judicious comparison is made among various LSPR-based approaches in terms of the assaying time, the sensitivity or lowest sensing concentration (i.e. limit of detection or LOD), and the single-base mismatch (SBM) selectivity.

Nanoparticle-protein interactions: a thermodynamic and kinetic study of the adsorption of bovine serum albumin to gold nanoparticle surfaces

Investigating the adsorption process of proteins on nanoparticle surfaces is essential to understand how to control the biological interactions of functionalized nanoparticles. In this work, a library of spherical and rod-shaped gold nanoparticles (GNPs) was used to evaluate the process of protein adsorption to their surfaces. The binding of a model protein (bovine serum albumin, BSA) to GNPs as a function of particle shape, size, and surface charge was investigated. Two independent comparative analytical methods were used to evaluate the adsorption process: steady-state fluorescence quenching titration and affinity capillary electrophoresis (ACE). Although under favorable electrostatic conditions kinetic analysis showed a faster adsorption of BSA to the surface of cationic GNPs, equilibrium binding constant determinations indicated that BSA has a comparable binding affinity to all of the GNPs tested, regardless of surface charge. BSA was even found to adsorb strongly to GNPs with a pegylated/neutral surface. However, these fluorescence titrations suffer from significant interference from the strong light absorption of the GNPs. The BSA-GNP equilibrium binding constants, as determined by the ACE method, were 10(5) times lower than values determined using spectroscopic titrations. While both analytical methods could be suitable to determine the binding constants for protein adsorption to NP surfaces, both methods have limitations that complicate the determination of protein-GNP binding constants. The optical properties of GNPs interfere with Ka determinations by static fluorescence quenching analysis. ACE, in contrast, suffers from material compatibility issues, as positively charged GNPs adhere to the walls of the capillary during analysis. Researchers seeking to determine equilibrium binding constants for protein-GNP interactions should therefore utilize as many orthogonal techniques as possible to study a protein-GNP system.

Micropatterned co-culture of hepatocyte spheroids layered on non-parenchymal cells to understand heterotypic cellular interactions

Microfabrication and micropatterning techniques in tissue engineering offer great potential for creating and controlling cellular microenvironments including cell-matrix interactions, soluble stimuli and cell-cell interactions. Here, we present a novel approach to generate layered patterning of hepatocyte spheroids on micropatterned non-parenchymal feeder cells using microfabricated poly(ethylene glycol) (PEG) hydrogels. Micropatterned PEG-hydrogel-treated substrates with two-dimensional arrays of gelatin circular domains (ϕ = 100 μm) were prepared by photolithographic method. Only on the critical structure of PEG hydrogel with perfect protein rejection, hepatocytes were co-cultured with non-parenchymal cells to be led to enhanced hepatocyte functions. Then, we investigated the mechanism of the functional enhancement in co-culture with respect to the contributions of soluble factors and direct cell-cell interactions. In particular, to elucidate the influence of soluble factors on hepatocyte function, hepatocyte spheroids underlaid with fibroblasts (NIH/3T3 mouse fibroblasts) or endothelial cells (BAECs: bovine aortic endothelial cells) were compared with physically separated co-culture of hepatocyte monospheroids with NIH3T3 or BAEC using trans-well culture systems. Our results suggested that direct heterotypic cell-to-cell contact and soluble factors, both of these between hepatocytes and fibroblasts, significantly enhanced hepatocyte functions. In contrast, direct heterotypic cell-to-cell contact between hepatocytes and endothelial cells only contributed to enhance hepatocyte functions. This patterning technique can be a useful experimental tool for applications in basic science, drug screening and tissue engineering, as well as in the design of artificial liver devices.

Amplification of resonant Rayleigh light scattering response using immunogold colloids for detection of lysozyme

A strategy for attomolar-level detection of small molecule-size proteins is reported based on Rayleigh light scattering spectroscopy of individual nanoplasmonic aptasensors by exploiting the outstanding characteristics of gold colloids to amplify the nontransparent resonant signal at ultralow analyte concentrations. The fabrication method utilizes thiol-mediated adsorption of a DNA aptamer on the immobilized Au nanoparticle surface, the interfacial binding characteristics of the aptamer with its target molecules, and the antibody-antigen interaction through plasmonic resonance coupling of the Au nanoparticles. Using lysozyme as a model analyte for disease detection, the detection limit of the aptasensor is ∼7 × 10(3) aM, corresponding to the LSPR λmax shift of ∼2.25 nm. Up to a 380% increase in the localized resonant λmax shift is demonstrated upon antibody binding to the analyte compared to the primary response during signal amplification using immunogold colloids. This enhancement leads to a limit of detection of ∼7 aM, which is an improvement of three orders of magnitude. The results demonstrate substantial promise for developing coupled plasmonic nanostructures for ultrasensitive detection of various biological and chemical analytes.

Improved stability of "naked" gold nanoparticles enabled by in situ coating with mono and multivalent thiol PEG ligands

Unprotected ("naked") gold nanoparticles with high monodispersity ([d], 5.5± 0.5 nm) were obtained in a facile and single-step microwave-assisted hydrolytic decomposition of the molecular precursor [NMe4][Au(CF3)2]. Given their chloride-free surface chemistry, the as-obtained gold nanoparticles were in situ functionalized with mono-, di-, and trivalent thiolated PEG ligands in order to study the influence of multivalent character of the ligands on the stability of the colloidal solutions. For this purpose, a novel tridentate ligand was synthesized and the previously reported syntheses of mono- and divalent thiol ligands were improved. Owing to the pristine character of the Au nanoparticles no ligand exchange was required, and the colloidal and chemical stability of the mono- and multivalent functionalized particles purely depended on the ligating ability of the thiolated groups. In situ-functionalized Au nanoparticles showed a strikingly (2 orders of magnitude higher) improved stability against small nucleophiles such as sodium cyanide compared to gold nanoparticles coated with citrate ligands and functionalized via a ligand-exchange reaction. The monovalent thiol PEG ligand produced most stable colloids against cyanide, which is explained by a strongly increased numerical ligand-density on the surface. Gold colloids stabilized by di- and trivalent ligands exhibited high stability in aqueous solutions with high NaCl concentrations (2 M) in contrast to those functionalized with the monovalent PEG ligand, which were only temporally stable in dilute NaCl solutions. The beneficial effect of the multivalence of the ligands was further demonstrated by the incorporation of an additional chelating ligand (dithiothreitol) to the colloidal dispersions.

Cysteine-mediated aggregation of Au nanoparticles: the development of a H2O2 sensor and oxidase-based biosensors

The cysteine-stimulated aggregation of Au nanoparticles (Au NPs) is used as an auxiliary reporting system for the optical detection of H2O2, for optical probing of the glucose oxidase (GOx) and the catalyzed oxidation of glucose, for probing the biocatalytic cascade composed of acetylcholine esterase/choline oxidase (AChE/ChOx), and for following the inhibition of AChE. The analytical paradigm is based on the I(-)-catalyzed oxidation of cysteine by H2O2 to cystine, a process that prohibits the cysteine-triggered aggregation of the Au NPs. The system enabled the analysis of H2O2 with a detection limit of 2 μM. As the GOx-biocatalyzed oxidation of glucose yields H2O2, and the AChE/ChOx cascade leads to the formation of H2O2, the two biocatalytic processes could be probed by the cysteine-stimulated aggregation of the Au NPs. Since AChE is inhibited by 1,5-bis(4-allyldimethylammonium phenyl)pentane-3-one dibromide, the biocatalytic AChE/ChOx cascade is inhibited by the inhibitor, thus leading to the enhanced cysteine-mediated aggregation of the NPs. The results suggest the potential implementation of the cysteine-mediated aggregation of Au NPs in the presence of AChE/ChOx as a sensing platform for the optical detection of chemical warfare agents.

Nanomaterials for ultrasensitive protein detection

The advances of nanomaterials have provided exciting technologies and novel materials for protein detection, based on the unique properties associated with nanoscale phenomena such as plasmon resonance, catalysis and energy transfer. This article reviews a series of nanomaterials including nanoparticles, nanofibers, nanowires, and nanosheets, and evaluates their performances in the application for protein detection, focusing on approaches that realize ultrasensitive detection. Many of these nanomaterials were used to analyze clinically relevant protein biomarkers. Their detection in the picomolar, femtomolar or even zeptomolar regime has been realized, sometimes even with naked-eye readout. We summarize the detection methods and results according to materials and targets, review the current challenges, and discuss the solution in the context of technological integration such as combining nanomaterials with microfluidics, and classical analytical technologies.

Influence of ligand presentation density on the molecular recognition of mannose-functionalised glyconanoparticles by bacterial lectin BC2L-A

Polyvalent carbohydrate-protein interactions play a key role in bio- and pathological processes, including cell-cell communication and pathogen invasion. In order to study, control and manipulate these interactions gold nanoparticles have been employed as a 3D scaffold, presenting carbohydrate ligands in a multivalent fashion for use as high affinity binding partners and a model system for oligosaccharide presentation at biomacromolecular surfaces. In this study, the binding of a series of mannose-functionalised gold nanoparticles to the dimeric BC2L-A lectin from Burkholderia cenocepacia has been evaluated. BC2L-A is known to exhibit a high specificity for (oligo)mannosides. Due to the unique structure and binding nature of this lectin, it provides a useful tool to study (oligo)saccharides presented on multivalent scaffolds. Surface plasmon resonance and isothermal titration calorimetric assays were used to investigate the effect of ligand presentation density towards binding to the bacterial lectin. We show how a combination of structural complementarities between ligand presentation and lectin architecture and statistical re-binding effects are important for increasing the avidity of multivalent ligands for recognition by their protein receptors; further demonstrating the application of glyconanotechnology towards fundamental glycobiology research as well as a potential towards biomedical diagnostics and therapeutic treatments.

CT imaging of myocardial scars with collagen-targeting gold nanoparticles

In the setting of myocardial ischemia, recovery of myocardial function by revascularization procedures depends on the extent of coronary disease and myocardial scar burden. Currently, computed tomographic (CT) imaging offers superior evaluation of coronary lesions but lacks the capability to measure the transmural extent of myocardial scar. Our work focuses on determining if collagen-targeting gold nanoparticles (AuNPs) can effectively target myocardial scar and provide adequate contrast for CT imaging. AuNPs were coated with a collagen-homing peptide, collagen adhesin (CNA35). Myocardial scar was created in mice by occlusion/reperfusion of the left anterior descending coronary artery. Thirty days later, un-gated CT imaging was performed. Over 6h, CNA35-AuNPs provided uniform and prolonged opacification of the vascular structures (100-130 HU). In mice with larger scar burden, focal contrast enhancement was detected in the myocardium, which was not apparent within that of control mice. Histological staining confirmed myocardial scar formation and accumulation of AuNPs.

FROM THE CLINICAL EDITOR

This team of investigators presents a collagen-targeting gold nanoparticle-based approach that enables the imaging of myocardial scars via CT scans in a rodent model. This information would enable clinicians to judge the recovery potential of myocardium more accurately than the current CT-scan based approaches.

Glyconanoparticles as multifunctional and multimodal carbohydrate systems

The quest for the construction of multivalent carbohydrate systems, with precise geometries that are highly efficient in interacting with carbohydrate binding proteins, has been a goal of synthetic chemists since the discovery of the multivalent nature of carbohydrate-mediated interactions. However, the control of the spatial and topological requirements for these systems is still a challenge. Glyconanoparticles (GNPs) are sugar-coated gold, iron oxide or semiconductor nanoparticles with defined thiol-ending glycosides that combine the multivalent presentation of carbohydrates (glycoclusters) with the special chemico-physical properties of the nano-sized metallic core. The possibility of attaching different types of carbohydrates and other molecules (such as luminescent probes, peptides, and magnetic chelates) onto the same gold nanoparticle in a controlled way (multifunctional GNPs), as well as modifying the core in order to obtain glyconanoparticles with magnetic or fluorescence properties (multimodal GNPs) makes this multivalent glyco-scaffold suitable for carrying out studies on carbohydrate-mediated interactions and applications in molecular imaging. In this review, we focus mainly on the rational design of glyconanoparticles as scaffolds for combining different ligands and survey the most recent examples of glyconanoparticles as both multivalent carbohydrate systems and probes for molecular imaging.

Chondrocyte spheroids on microfabricated PEG hydrogel surface and their noninvasive functional monitoring

A two-dimensional microarray of 10 000 (100 × 100) chondrocyte spheroids was constructed with a 100 μm spacing on a micropatterned gold electrode that was coated with poly(ethylene glycol) (PEG) hydrogels. The PEGylated surface as a cytophobic region was regulated by controlling the gel structure through photolithography. In this way, a PEG hydrogel was modulated enough to inhibit outgrowth of chondrocytes from a cell adhering region in the horizontal direction, which is critical for inducing formation of three-dimensional chondrocyte aggregations (spheroids) within 24 h. We further report noninvasive monitoring of the cellular functional change at the cell membrane using a chondrocyte-based field effect transistor. This measurement is based on detection of extracellular potential change induced as a result of the interaction between extracellular matrix protein secreted from spheroid and substrate at the cell membrane. The interface potential change at the cell membrane/gate interface can be monitored during the differentiation of spheroids without any labeling materials. Our measurements of the time evolution of the interface potential provide important information for understanding the uptake kinetics for cellular differentiation.

Effects of nanopolystyrene on the feeding behavior of the blue mussel (Mytilus edulis L.)

As the industrial production of nanoplastic and the degradation of microplastic into smaller particles at sea increase, the potential amount of nanoplastics in the marine environment rises. It has been reported that mussels uptake 100-nm polystyrene (PS) beads; to date, however, the effects of this uptake on the organism are unknown. In the present study, the authors investigated the effects of 30-nm PS on the feeding behavior of the blue mussel (Mytilus edulis) by exposing the organism to different nano PS and different algae (Pavlova lutheri) concentrations. The state of nano PS aggregation in the exposure medium was assessed using dynamic light scattering. In all treatments that contained nano PS, M. edulis produced pseudofeces. The total weight of the feces and pseudofeces increased with increasing nano PS and increasing algae concentration. Furthermore, M. edulis reduced its filtering activity when nano PS was present but still caused a decrease in the apparent nano PS concentration in the water. The presence of nano PS around the foot of M. edulis after the bioassay confirmed that the organism removed nano PS from the water. Chronic effect studies are therefore needed to investigate the effects of nanoplastics in M. edulis and possible consequences for its predators, including humans.

Syntheses of sulfo-glycodendrimers using click chemistry and their biological evaluation

A series of novel glycol-clusters containing sulfonated N-acetyl-D-glucosamine (GlcNAc) have been synthesized using click chemistry. Three dendrimers with aromatic dendrons were synthesized using chlorination, azidation and click chemistries. The resulting dendrimers were modified with azide-terminated sulfonated GlcNAc using click chemistry. The sulfonated dendrimers showed affinity for proteins, including the lectin wheat germ agglutinin and amyloid beta peptide (1-42). The dendrimers of G1 and G2 in particular showed the largest affinity for the proteins. The addition of the sulfonated GlcNAc dendrimers of G1 and G2 exhibited an inhibition effect on the aggregation of the amyloid beta peptide, reduced the β-sheet conformation, and led to a reduction in the level of nanofiber formation.