Multi-Stimuli-Responsive Water-Dispersible Magnetite Nanoparticles Using Arylazopyrazole-Modified Polymer Ligands

In order to design new nanomaterials with improved functionalities, magnetite nanoparticles (MNP) modified with arylazopyrazole (AAP) molecular photoswitches are presented. Water dispersibility is achieved by using poly(acrylic acid) (pAA) as a multidentate ligand, which is modified with AAP by amide coupling. The polymer ligand stabilizes the MNP, allows for E-Z isomerization of the photoswitch, and provides pH responsiveness. Three different AAP are synthesized and attached to pAA via amide coupling giving pAA-AAP with photoswitches substituted statistically along the hydrophilic polymer backbone. MNP are synthesized by coprecipitation and pAA-AAP is introduced as a stabilizing agent in situ. Photoisomerization of pAA-AAP and pAA-AAP@MNP is investigated showing good photostationary states and cyclability. The MNP can be assembled and dispersed reversibly in water either by applying a magnetic field or by a change in pH.

Histidine modified Fe3O4 nanoparticles improving the ethanol yield and tolerance of Saccharomyces cerevisiae

Saccharomyces cerevisiae, the primary microorganism involved in ethanol production, is hindered by the accumulation of ethanol, leading to reduced ethanol production. In this study, we employed histidine-modified Fe3O4 nanoparticles (His-Fe3O4) for the first time, to the best of our knowledge, as a method to enhance ethanol yield during the S. cerevisiae fermentation process. The results demonstrated that exposing S. cerevisiae cells to Fe3O4 nanoparticles (Fe3O4 NPs) led to increased cell proliferation and glucose consumption. Moreover, the introduction of His-Fe3O4 significantly boosted ethanol content by 17.3% (p < 0.05) during fermentation. Subsequent findings indicated that the increase in ethanol content was associated with enhanced ethanol tolerance and improved electron transport efficiency. This study provided evidence for the positive effects of His-Fe3O4 on S. cerevisiae cells and proposed a straightforward approach to enhance ethanol production in S. cerevisiae fermentation. The mediation of improved ethanol tolerance offers significant potential in the fermentation and bioenergy sectors.

Fe3O4@SiO2@NiAl-LDH microspheres implication in separation, kinetic and structural properties of phenylalanine dehydrogenase

Fe3O4@SiO2@NiAl-LDH three-components microsphere contains a Fe3O4@SiO2 magnetic core and a layered double hydroxide with nickel cation provide the binding ability to (His)-tagged-protein and exhibits high performance in protein separation and purification. The morphology and chemistry of the synthesized Fe3O4@SiO2@NiAl-LDH microspheres were characterized by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), vibrating sample magnetometer (VSM), Dynamic light scattering (DLS). Purified enzyme was assesed with SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis and intrinsic fluorescence spectroscopy. In this study, the separation of phenylalanine dehydrogenase (PheDH) by Fe3O4@SiO2@NiAl -LDH was performed and the effect of microsphere was investigated on the kinetic and structural properties of PheDH. After purification, kinetic parameters such as Km, Vmax, Kcat, kcat/Km, optimum temperature, thermal stability, and and activation energy were evaluated and compared according to the mentioned methods. The interaction between the enzyme and the microsphere displayed a high performance in protein binding capacity. The results also revealed that the kinetic parameters of the enzyme changed in a dose-dependent manner in the presence of a microsphere. Moreover, the results of intrinsic fluorescence and Circular Dichroism (CD) confirmed the structural changes of the protein in the interaction with the microsphere.

Switchable Separation Strategy via Host-Guest Locks

Universal separation strategies are the ultimate goal in separation science. However, there is always a tradeoff between universality and selectivity due to the negative influence among different recognition domains. With the goal of universal separation in mind, an unprecedented, switchable, and versatile separation strategy using reversible supramolecular host-guest interactions has been developed. These adjustable separation mediums were prepared using surface-grafted cationic cyclodextrin to firmly bind negatively charged adamantane derivatives. By changing guest structures, the surface functionality of the separation medium can be precisely regulated to be selective for a variety of substrates including chiral or achiral molecules, thus producing satisfactory single-column universality. This method offers a new approach to move beyond conventional separation methodologies and should stimulate the design of switchable functional materials.

Ionic Liquid Modified SPION@Chitosan as a Novel and Reusable Superparamagnetic Catalyst for Green One-Pot Synthesis of Pyrido[2,3-d]pyrimidine-dione Derivatives in Water

In this paper, the chitosan-functionalized ionic liquid is modified with superparamagnetic iron oxide nanoparticles to form a novel and reusable catalyst (SPION@CS-IL), which was carried out using an ultrasonic promoted approach. Transmission electron microscopy (TEM), vibrating-sample magnetometer (VSM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and thermogravimetric analysis (TGA) are some of the techniques that are used to fully characterize SPION@CS-IL. The created nanoparticles were discovered to be a reusable heterogeneous superparamagnetic catalyst for the environmentally friendly one-pot synthesis of pyrido[2,3-d]pyrimidine derivatives using a simple three-component reaction approach involving thiobarbituric acid, 4-hydroxy coumarin, and various aromatic aldehydes. The method is studied by performing the reaction under ultrasonic irradiation, while the approach is a “green” method, it uses water as the solvent. The isolated yields of the synthesized products are very advantageous. The catalyst has outstanding reusability and is easily removed from the products via filtration (5 runs). Short reaction times, low catalyst loadings, the nanocatalyst’s capacity to be recycled five times, and the absence of harmful chemical reagents are all significant benefits of this environmentally benign process.

Layer-by-layer assembly of multilayered double hydroxides/polyoxometalate-coated magnetic nanoparticles for highly efficient phosphopeptide enrichment

A layer-by-layer (LbL) assembly strategy was developed to prepare multilayered double hydroxide/polyoxometalate shell-coated magnetic nanoparticles. The introduction of functional shells not only offered abundant affinity sites of metal oxide and metal ions but also increased the surface area for the contact with targets. By combining the enrichment strategies of immobilized metal ion affinity chromatography and metal oxide affinity chromatography, the nanomaterial can capture phosphopeptides via a synergistic effect. The method presented a low detection limit of 0.1 fmol in combination with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis. The nanomaterial showed satisfactory selectivity (1:1:5000 M ratio of α-/β-casein/bovine serum albumin), good recovery (92.07%), high adsorption capacity (117.6 mg g^-1), and ten times reusability for capturing phosphopeptides.

Fabrication of Fe3O4@poly(methyl methacrylate-co-glycidyl methacrylate) microspheres via miniemulsion polymerization using porous microspheres as templates for removal of cationic dyes

A novel and simple method was proposed to prepare monodisperse magnetic microspheres with controllable particle sizes and different functionalities.

Magneto-responsive hydrogels by self-assembly of low molecular weight peptides and crosslinking with iron oxide nanoparticles

Hydrogels that respond to non-invasive, external stimuli such as a magnetic field are of exceptional interest for the development of adaptive soft materials. To date magneto tuneable gels are predominantly based on macromolecular building blocks, while comparable low molecular weight systems are rarely found in the literature. Herein, we report a highly efficient peptide-based gelator (Nap GFYE), which can form hydrogels and incorporate Fe3O4 superparamagnetic nanoparticles in the gel matrix. The magnetic nanoparticles act as a physical crosslinker for the self-assembled peptide nanostructures and thus give rise to a fortified hybrid gel with distinctively improved mechanical properties. Furthermore, the particles provide the material with magnetic susceptibility and a gel to sol transition is observed upon application of a weak magnetic field. Magnetization of the inorganic-organic hybrid nanomaterial leads to on-demand release of an incorporated fluorescent dye into the supernatant.

Sample preparation considerations for surface and crystalline properties and ecotoxicity of bare and silica-coated magnetite nanoparticles

Magnetite (Fe₃O₄) nanoparticles (NPs) have widely used in various fields, including in medicine, due to their (super)paramagnetic properties. This requires a thorough evaluation of their possible hazardous effects. However, there is no standard procedure for the preparation of oxidation-prone NPs (such as magnetite) before subjecting them to biological assays. In this study we used Fe₃O₄ NPs (bare and silica-coated) as test samples to compare different preparation methods (ultrasound, centrifugation and filteration of NPs suspensions) based on X-ray and dynamic light scattering analysis and evaluation of microstructure and surface charge. After oxidation and functionalization, all samples retained their superparamagnetic behaviour. The toxicity of NP suspensions obtained by the methods described for Paramecium caudatum ciliates and Sinapis alba plants was evaluated.

The charge and surface reactivity of magnetite nanoparticles can be affected by the different separation methods leading to their toxicity changes.

Cyclodextrin-Based Functional Glyconanomaterials

Cyclodextrins (CDs) have long occupied a prominent position in most pharmaceutical laboratories as "off-the-shelve" tools to manipulate the pharmacokinetics of a broad range of active principles, due to their unique combination of biocompatibility and inclusion abilities. The development of precision chemical methods for their selective functionalization, in combination with "click" multiconjugation procedures, have further leveraged the nanoscaffold nature of these oligosaccharides, creating a direct link between the glyco and the nano worlds. CDs have greatly contributed to understand and exploit the interactions between multivalent glycodisplays and carbohydrate-binding proteins (lectins) and to improve the drug-loading and functional properties of nanomaterials through host-guest strategies. The whole range of capabilities can be enabled through self-assembly, template-assisted assembly or covalent connection of CD/glycan building blocks. This review discusses the advancements made in this field during the last decade and the amazing variety of functional glyconanomaterials empowered by the versatility of the CD component.

Preparation, surface functionalization and application of Fe3O4 magnetic nanoparticles

This paper reviews recent developments in the preparation, surface functionalization, and applications of Fe₃O₄ magnetic nanoparticles. Especially, it includes preparation methods (such as electrodeposition, polyol methods, etc.), organic materials (such as polymers, small molecules, surfactants, biomolecules, etc.) or inorganic materials (such as silica, metals, and metal oxidation/sulfide, functionalized coating of carbon surface, graphene, etc.) and its applications (such as magnetic separation, protein fixation, magnetic catalyst, environmental treatment, medical research, etc.). In the end, some existing challenges and possible future trends in the field were discussed.

Cyclodextrin-based superparamagnetic host vesicles as ultrasensitive nanobiocarriers for electrosensing

A carbohydrate-based nanohybrid of superparamagnetic nanoparticles embedded in unilamellar bilayer vesicles of amphiphilic β-cyclodextrins (magnetic cyclodextrin vesicles, mCDVs) has been engineered as a novel magnetic biorecognition probe for electrosensing. As a proof-of-concept, the synergistic properties of these mCDVs on a magneto nanocomposite carbon-paste electrode (mNC-CPE) have been used for the picomolar determination of thyroxine (T4) as a model analyte (taking advantage of the host-guest chemistry of β-cyclodextrin and T4), resulting in the most sensitive electrochemical T4 system reported in the literature. Accordingly, a first demonstration of mCDVs as alternative water-soluble magnetic nanobiocarriers has been devised foreseeing their successful use as alternative electrochemical biosensing platforms for the supramolecular trace determination of alternative targets.

Design of Functional Magnetic Nanocomposites for Bioseparation

Magnetic materials have been widely used in bioseparation in recent years due to their good biocompatibility, magnetic properties, and high binding capacity. In this review, we provide a brief introduction on the preparation and bioseparation applications of magnetic materials including the synthesis and surface modification of magnetic nanoparticles as well as the preparation and applications of magnetic nanocomposites in the separation of proteins, peptides, cells, exosomes and blood. The current limitations and remaining challenges in the fabrication process of magnetic materials for bioseparation will be also detailed.

Selection of Affinity Reagents to Neutralize the Hemolytic Toxicity of Melittin Based on a Self-Assembled Nanoparticle Library

Antibodies are the most common affinity reagents for specific target recognition. However, their applications are limited by high cost and low stability. Thus, seeking substitutes for antibodies is of great significance. In this work, we designed a library containing 82 self-assembled nanoparticles (SNPs) based on the self-assembly of β-cyclodextrin polymers and adamantane derivatives, and then screened out eight types of SNPs capable of suppressing the toxicity of melittin using a hemolytic activity neutralization assay. The affinities of the SNPs to melittin were demonstrated using surface plasmon resonance (SPR). As evidenced by cytotoxicity experiments, SNPs could also suppress the toxicity of melittin to other cells. In addition, to verify the universality of our method, 11 types of SNPs capable of neutralizing another toxic peptide, phenolic soluble polypeptide (PSMα3) secreted by Staphylococcus aureus, were selected from the same SNP library. Our self-assembly-based method for the library preparation has the advantages of flexible design, mild experimental condition, and simple operation, which is expected to seek artificial affinity reagents for more species.

Functionalization of Clinically Approved MRI Contrast Agents for the Delivery of VEGF

In combining the two clinically approved substances ferumoxytol and VEGF-165 via peptide coupling, we propose a straightforward approach to obtain a potentially ready-to-use theranostic contrast agent for specific cardiovascular diseases. Clinical and preclinical magnetic resonance imaging (MRI) studies have shown that intravenously applied superparamagnetic ferumoxytol nanoparticles accumulate in acute ischemic myocardial tissue. On the other hand, growth factors such as VEGF-165 (vascular endothelial growth factor) play a major role during angiogenesis and vasculogenesis. Promising clinical studies with systemic application of VEGF-165 have been performed in the past. However, following untargeted systemic application, the biological half-life of VEGF-165 was too short to develop its full effect. Therefore, we hypothesized that ferumoxytol particles functionalized with VEGF-165 will accumulate in ischemic myocardial regions and can be detected by MRI, while the prolonged retention of VEGF-165 due to ferumoxytol-coupling will help to prevent adverse tissue remodeling. In addition, strategies such as magnetic targeting can be used to enhance targeted local accumulation. As a precondition for further preclinical research, we confirmed the successful coupling between ferumoxytol and VEGF-165 in detail (TEM, XPS, and IR spectroscopy), characterized the functionalized ferumoxytol particles (DLS, TEM, and MRI) and performed in vitro tests that showed their superior effect on cell growth and survival.

Co-assemblies of polyoxometalate {Mo72Fe30}/double-tailed magnetic-surfactant for magnetic-driven anchorage and enrichment of protein

Covalent grafting and electrostatic-driven assembly have been two strategies in constructing well-defined polyoxometalate (POM) assemblies to produce specific morphologies and desirable properties. The modification of anionic counter-ions of amphiphilic compounds in POM-surfactant hybrid systems is still unexploited. Herein, we report the co-assembly of a synthetic double-tailed magnetic surfactant (MagSurf), (C₁₈)₂C₂N⁺[FeCl₄]^-, and POM, {Mo₇₂Fe₃₀}. The magnetic aggregate (POM/MagSurf) results from the building up hierarchical structures at a time-dependent interface. In this construct, both the MagSurfs and {Mo₇₂Fe₃₀} POMs contribute to and mutually strengthen the magnetization of the designed magnetic assembles. Interestingly, the POM/MagSurf aggregates are compatible with aqueous mixtures and successfully employed to serve as magnetic transporting vehicles to anchor and deliver a protein molecule, myoglobin (Mb). Upon applying a magnetic field (0.3 T), the magnetic aggregates induced a directional migration and enrichment of the Mb protein (71-90%). During this process, the protein/POM/MagSurf complexes exhibited strong interactions facilitating stable anchoring and efficient enrichment of the Mb.

Structure and luminescence properties of supramolecular polymers of amphiphilic aromatic thioether–peptide conjugates in water

We present the preparation of luminophore–peptide conjugates that self-assemble into phosphorescent supramolecular polymers in neutral buffer.

Magnetic glyconanoparticles for selective lectin separation and purification

A modular platform for the separation and purification of lectins using polymer coated iron oxide nanoparticles is developed.

Glucose oxidation performance is improved by the use of a supramolecular self-assembly of glucose oxidase and catalase

A multi-enzymes complex was assembled successfully via host/guest interactions, and it was used for rapid transformation of glucose.

Self-Assembled Magnetic Viruslike Particles for Encapsulation and Delivery of Deoxyribonucleic Acid

Developing nontoxic artificial carriers for stimuli-responsive capture, transport, and delivery of biomolecules is of immense scientific interest. Herein, for the first time, we synthesize a double-tailed cationic surfactant, (C₁₆H₃₃)₂(CH₃)₂N⁺[FeCl₃Br]^-, which possesses magnetic properties [magnetic surfactants (Mag-Surfs)]. The time-dependent formation of virus-shaped hybrid mixed assemblies of polyoxometalates (POMs) {Mo₇₂Fe₃₀}/Mag-Surf with hollow-shell structures is followed. These structures serve well as robust high-surface-area shuttles, which can be manipulated with applied magnetic fields. By using cationic Mag-Surfs, the anionic POMs and DNA can be complexed in these ternary mixtures. These virus-shaped complexes act as nanoanchors and nanomotors, which can be utilized for binding, anchoring, and delivery of biomolecules, such as DNA. It is found that they have a good absorption capacity for DNA and myoglobin over 24 h, after application of a magnetic field. The realization of magnetic virus-shaped {Mo₇₂Fe₃₀}/Mag-Surf spheres may open possibilities for designing other functional nanoparticles, allowing effective control over the delivery/separation of biomolecules.

A magnetic hydrazine-functionalized dendrimer embedded with TiO2 as a novel affinity probe for the selective enrichment of low-abundance phosphopeptides from biological samples

Dendrimers exhibit tunable terminal functionality and bio-friendly nature, making them of being promising materials for applications in the field of separation and enrichment. In this work, we prepared magnetic hydrazide-functionalized poly-amidoamine (PAMAM) dendrimer embedded with TiO₂ for the enrichment of phosphopeptides. The novel affinity probe possessed superparamagnetism, realizing its rapid separation from sample solution. Electrostatic attraction and hydrogen bonding existed between PAMAM and phosphopeptides while Lewis acid-base interaction was originated between TiO₂ and the targets. The combined synergistic strength of multiple binding interactions contributed to the highly selective enrichment of phosphopeptides. The specificity for the capture of phosphopeptides was reflected in quantities as low as 1:1000 mass ratio of phosphopeptides to non-phosphopeptides. The detection limit of β-casein digests was low to 0.4 fmol, indicating the high sensitivity of the developed method. Fifteen and four phosphopeptides could be selectively captured from non-fat milk digests and human serum samples, which further confirmed the great potential of the affinity probe in the extraction of low-abundance phosphopeptides from real complex biological samples.

A supramolecular approach for versatile biofunctionalization of magnetic nanoparticles

A convenient and versatile approach for biofunctionalization of magnetic nanoparticles was developed based on supramolecular host–guest interaction.

Stabilization of High Oxidation State Upconversion Nanoparticles by N-Heterocyclic Carbenes

The stabilization of high oxidation state nanoparticles by N-heterocyclic carbenes is reported. Such nanoparticles represent an important subset in the field of nanoparticles, with different and more challenging requirements for suitable ligands compared to elemental metal nanoparticles. N-Heterocyclic carbene coated NaYF₄ :Yb,Tm upconversion nanoparticles were synthesized by a ligand-exchange reaction from a well-defined precursor. This new photoactive material was characterized in detail and employed in the activation of photoresponsive molecules by low-intensity near-infrared light (λ=980 nm).

Poly(benzofuran-co-arylacetic acid) – a new type of highly functionalized polymers

A new type of polymer containing a number of functional groups with orthogonal reactivity, allowing linkage to several functionalities.

Facile synthesis of thiazole-functionalized magnetic microspheres for highly specific separation of heme proteins

Thiazole-functionalized magnetic microspheres which exhibited high selectivity to capture hemoglobin with a binding capacity of 2.02 g g⁻¹ were successfully synthesized.

Controllable preparation of core–shell magnetic covalent-organic framework nanospheres for efficient adsorption and removal of bisphenols in aqueous solution

A monomer-mediated in situ growth strategy has been developed for the controllable fabrication of magnetic COF core–shell nanostructures with great potential for wide applications.

Self-assembly of colloidal molecules that respond to light and a magnetic field

Janus particles with polymer caps self-assemble into dual responsive particle chains that can be manipulated with light and a magnetic field.

Near-infrared photoswitching of cyclodextrin–guest complexes using lanthanide-doped LiYF4 upconversion nanoparticles

This communication reports a new type of supramolecular cyclodextrin–guest complexes using cyclodextrin coated upconversion nanoparticles as hosts and monovalent and divalent azobenzenes and arylazopyrazoles as guests.

Host–guest interactions and controllable capture and release of proteins based on cationic perylene bisimides

A system of controllable capture and release of protein was constructed by multiple, interconnected supramolecular binding modules based on lactose modified mono-cationic perylene bisimide derivatives, cucurbit[8]uril (CB[8]), 1-adamantanamine (ADA) and peanut agglutinin (PNA) lectins.

Supramolecular Double-Helix Formation by Diastereoisomeric Conformations of Configurationally Enantiomeric Macrocycles

Solid-state superstructures, resulting from assemblies programmed by homochirality, are attracting considerable attention. In addition, artificial double-helical architectures are being investigated, especially in relation to the ways in which homochiral small molecules can be induced to yield helical forms as a result of chiral induction. Herein, we report the highly specific self-assembly upon crystallization of a double-helical superstructure from an enantiopure macrocyclic dimer which adopts two diastereoisomeric conformations in a molar ratio of 1.5:1 in dimethyl sulfoxide. These two conformational diastereoisomers self-organize-and self-sort-in the crystalline phase in equimolar proportions to form two single-handed helices which are complementary to each other, giving rise to the assembly of a double helix that is stabilized by intermolecular [C-H···O] and π-π stacking interactions. The observed self-sorting phenomenon occurs on going from a mixed-solvent system containing two equilibrating conformational diastereoisomers, presumably present in unequal molar proportions, into the solid state. The diastereoisomeric conformations are captured upon crystallization in a 1:1 molar ratio in the double-helical superstructure, whose handedness is dictated by the choice of the enantiomeric macrocyclic dimer. The interconversion of the two conformational diastereoisomers derived from each configurationally enantiomeric macrocycle was investigated in CD₃SOCD₃ solution by variable-temperature ¹H NMR spectroscopy (VT NMR) and circular dichroism (VT CD). The merging of the resonances for the protons corresponding to the two diastereoisomers at a range of coalescence temperatures in the VT NMR spectra and occurrence of the isosbestic points in the VT CD spectra indicate that the two diastereoisomers are interconverting slowly in solution on the ¹H NMR time scale but rapidly on the laboratory time scale. To the best of our knowledge, the self-assembly of such solid-state superstructures from two conformational diastereoisomers of a homochiral macrocycle is a rare, if not unique, occurrence.

A versatile approach towards multivalent saccharide displays on magnetic nanoparticles and phospholipid vesicles

A simple synthetic route has been devised for the production of coating agents that can give multivalent displays of saccharides on the surface of magnetite nanoparticles and phospholipid vesicles. A versatile and potentially high-throughput condensation reaction allowed the rapid synthesis of a variety of glycosylhydrazide conjugates with lipid, resorcinol or catechol termini, each in good yield and high anomeric purity. The hydrolytic stability of these adducts was assessed in D2O at different pD values using (1)H-NMR spectroscopy, whilst quartz crystal microbalance with dissipation monitoring (QCM-D) confirmed that the saccharide functionality on bilayers and on nanoparticles was still available to lectins. These multivalent saccharide displays promoted nanoparticle interactions with cells, for example N-acetylglucosamine-coated nanoparticles interacted much more effectively with 3T3 fibroblasts than uncoated nanoparticles with these cells. Despite potential sensitivity to oxidation, catechol coatings on magnetite nanoparticles were found to be more stable and generate better nanoparticle interactions with fibroblasts than resorcinol coatings.

Capture and Recycling of Sortase A through Site-Specific Labeling with Lithocholic Acid

Enzyme-mediated protein modification often requires large amounts of biocatalyst, adding significant costs to the process and limiting industrial applications. Herein, we demonstrate a scalable and straightforward strategy for the efficient capture and recycling of enzymes using a small-molecule affinity tag. A proline variant of an evolved sortase A (SrtA 7M) was N-terminally labeled with lithocholic acid (LA)-an inexpensive bile acid that exhibits strong binding to β-cyclodextrin (βCD). Capture and recycling of the LA-Pro-SrtA 7M conjugate was achieved using βCD-modified sepharose resin. The LA-Pro-SrtA 7M conjugate retained full enzymatic activity, even after multiple rounds of recycling.

Ligand-Free Fe3 O4 /CMCS Nanoclusters with Negative Charges for Efficient Structure-Selective Protein Adsorption

The easy and effective capture of a single protein from a complex mixture is of great significance in proteomics and diagnostics. However, adsorbing nanomaterials are commonly decorated with specific ligands through a complicated and arduous process. Fe3 O4 /carboxymethylated chitosan (Fe3 O4 /CMCS) nanoclusters are developed as a new nonligand modified strategy to selectively capture bovine hemoglogin (BHB) and other structurally similar proteins (i.e., lysozyme (LYZ) and chymotrypsin (CTP)). The ligand-free Fe3 O4 /CMCS nanoclusters, in addition to their simple and economical two-step preparation process, possess many merits, including uniform morphology, high negative charges (-27 mV), high saturation magnetization (60 emu g(-1) ), and high magnetic content (85%). Additionally, the ligand-free Fe3 O4 /CMCS nanoclusters are found to selectively capture BHB in a model protein mixture even within biological samples. The reason for selective protein capture is further investigated from nanomaterials and protein structure. In terms of nanomaterials, it is found that high negative charges are conducive to selectively adsorb BHB. In consideration of protein structure, interestingly, the ligand-free magnetic nanoclusters display a structure-selective protein adsorption capacity to efficiently capture other proteins structurally similar to BHB, such as LYZ and CTP, showing great potential of the ligand-free strategy in biomedical field.

Carbohydrates in Supramolecular Chemistry

Carbohydrates are involved in a variety of biological processes. The ability of sugars to form a large number of hydrogen bonds has made them important components for supramolecular chemistry. We discuss recent advances in the use of carbohydrates in supramolecular chemistry and reveal that carbohydrates are useful building blocks for the stabilization of complex architectures. Systems are presented according to the scaffold that supports the glyco-conjugate: organic macrocycles, dendrimers, nanomaterials, and polymers are considered. Glyco-conjugates can form host-guest complexes, and can self-assemble by using carbohydrate-carbohydrate interactions and other weak interactions such as π-π interactions. Finally, complex supramolecular architectures based on carbohydrate-protein interactions are discussed.

Precise Macroscopic Supramolecular Assembly by Combining Spontaneous Locomotion Driven by the Marangoni Effect and Molecular Recognition

Macroscopic supramolecular assembly bridges fundamental research on molecular recognition and the potential applications as bulk supramolecular materials. However, challenges remain to realize stable precise assembly, which is significant for further functions. To handle this issue, the Marangoni effect is applied to achieve spontaneous locomotion of macroscopic building blocks to reach interactive distance, thus contributing to formation of ordered structures. By increasing the density of the building blocks, the driving force for assembly transforms from a hydrophobic-hydrophobic interaction to hydrophilic-hydrophilic interaction, which is favorable for introducing hydrophilic coatings with supramolecular interactive groups on matched surfaces, consequently realizing the fabrication of stable precise macroscopic supramolecular assemblies.