4-vinylpyridine Research Articles

Highly Cross-Linked butene grafted poly (Vinyl Alcohol)–co-Vinyl pyridine based anion exchange membrane for improved acid recovery and desalination efficiency

Water treatment and waste acid reclamation are important in present situation due to huge industrialization. Different processes are available for the water treatment and waste treatment. Ion exchange membranes based electrodialysis (ED) and diffusion dialysis (DD) are attracted by the researchers since last decade due to its simplicity and economical operation. Acid reclamation by diffusion dialysis has been gained huge attention due to their absolute selectivity and energy less process. Here, we report the synthesis of efficient anion exchange membrane (AEM) by free radical co-polymerization of butene grafted poly (vinyl alcohol) and 4-vinyl pyridine followed by in-situ quaternization and cross-linking. Different amount 4-vinyl pyridine was chosen for the membrane preparation, and its impact on physiochemical and electrochemical properties has been studied. Structural and chemical characterisation of the membranes were studied using nuclear magnetic resonance (NMR), attenuated total reflectance-infrared spectroscopy (ATR-IR), while surface-phase morphology was investigated through scanning electron microscopy (SEM) and atomic force microscopy (AFM). The thermo-mechanical properties of prepared membranes were studied using thermogravimetric analysis (TGA), differential scanning colorimetry (DSC), dynamic mechanical analysis (DMA) and universal testing machine (UTM) analysis. The cross-linked PVA-x membranes showed high acidic stability as well as good antioxidation property. The synthesized membranes were studied for their salt removal performance by electrodialysis and acid recovery by diffusion dialysis. The optimised membrane (PVA-0.8) shows 0.90 kWh kg−1 energy consumption and 93.49 % current efficiency during salt removal from brackish water using electrodialysis. All cross-linked PVA-x membranes have diffusion coefficient of acid are in the range of 0.0556–0.0716 mh−1 and separation factor values are between the 79.51 to 91.33 at 25 °C, which comparable to commercial DF-120B membrane. This result shows that the prepared cross-linked AEMs may be a good candidate for the electrochemical applications.

Polymer Gel with Tunable Conductive Properties: A Material for Thermal Energy Harvesting.

The spontaneous gelation of poly(4-vinyl pyridine)/pyridine solution produces materials with conductive properties that are suitable for various energy conversion technologies. The gel is a thermoelectric material with a conductivity of 2.2-5.0 × 10-6 S m-1 and dielectric constant ε = 11.3. On the molecular scale, the gel contains various types of hydrogen bonding, which are formed via self-protonation of the pyridine side chains. Our measurements and calculations revealed that the gelation process produces bias-dependent polymer complexes: quasi-symmetric, strongly hydrogen-bonded species, and weakly bound protonated structures. Under an applied DC bias, the gelled complexes differ in their capacitance/conductive characteristics. In this work, we exploited the bias-responsive characteristics of poly(4-vinyl pyridine) gelled complexes to develop a prototype of a thermal energy harvesting device. The measured device efficiency is S = ΔV/ΔT = 0.18 mV/K within the temperature range of 296-360 K. Investigation of the mechanism underlying the conversion of thermal energy into electric charge showed that the heat-controlled proton diffusion (the Soret effect) produces thermogalvanic redox reactions of hydrogen ions on the anode. The charge can be stored in an external capacitor for heat energy harvesting. These results advance our understanding of the molecular mechanisms underlying thermal energy conversion in the poly(4-vinyl pyridine)/pyridine gel. A device prototype, enabling thermal energy harvesting, successfully demonstrates a simple path toward the development of inexpensive, low-energy thermoelectric generators.

Protein cysteine S-glycosylation: oxidative hydrolysis of protein S-glycosidic bonds in aqueous alkaline environments

Some glycoproteins contain carbohydrates S-linked to cysteine (Cys) residues. However, relatively few S-glycosylated proteins have been detected, due to the lack of an effective research methodology. This work outlines a general concept for the detection of S-glycosylation sites in proteins. The approach was verified by exploratory experiments on a model mixture of β-S-glucosylated polypeptides obtained by the chemical transformation of lysozyme P00698. The model underwent two processes: (1) oxidative hydrolysis of S-glycosidic bonds under alkaline conditions to expose the thiol group of Cys residues; (2) thiol S-alkylation leading to thiol S-adduct formation at the former S-glycosylation sites. Oxidative hydrolysis was conducted in aqueous urea, dimethyl sulfoxide, or trifluoroethanol, with silver nitrate as the reaction promoter, in the presence of triethylamine and/or pyridine. The concurrent formation of stable protein silver thiolates, gluconic acid, and silver nanoclusters was observed. The essential de-metalation of protein silver thiolates using dithiothreitol preceded the S-labeling of Cys residues with 4-vinyl pyridine or a fluorescent reagent. The S-labeled model was sequenced by tandem mass spectrometry to obtain data on the modifications and their distribution over the protein chains. This enabled the efficiency of both S-glycosidic bonds hydrolysis and S-glycosylation site labeling to be evaluated. Suggestions are also given for testing this novel strategy on real proteomic samples.

Synthesis, characterisation and optimisation of bulk molecularly imprinted polymers from nonsteroidal anti-inflammatory drugs

The scope of this study was to synthesise and characterise the multi-template molecularly imprinted polymer (MIP) and to use target compounds, naproxen, ibuprofen, diclofenac, fenoprofen and gemfibrozil as templates so as to achieve all maximum extraction efficiency for all compounds. These compounds are a class of nonsteroidal anti-inflammatory drugs (NSAIDs) generally used by humans, as they have pain-relieving activities. MlPs are cross-linked polymeric materials that display high binding capacity and selectivity towards templates of interest. The synthesis consisted of a bulk polymerisation process at 60 °C by using NSAIDs as multi-templates, ethylene glycol dimethacrylate (EGDMA), 2-vinyl pyridine (2VP) and toluene as cross-linker, functional monomer and porogen, respectively. Nonimprinted polymer (NIP) was synthesised in a similar manner with the omission of the templates. Characteristics of the polymers were analysed using Scanning Electron Microscopy (SEM), Fourier Transformed Infrared Spectroscopy (FTIR), Solid State Nuclear Magnetic Resonance Spectroscopy (NMR) and Thermal Gravimetric Analysis (TGA). An adsorption method of NSAIDs using the bulk polymerised MIP was investigated under various pH, mass, concentration and time conditions. Other parameters included adsorption kinetics and adsorption isotherms. Uptake of NSAIDs from an aqueous medium was achieved with 40 mg of MIP at pH 4.0 within 10 min of contact time. The extraction efficiencies achieved for NSAIDs in aqueous solutions ranged from 90-98% for all compounds tested. The adsorption capacity obtained for MIP ranged from 1.230-1.249 mg g-1 and 0.90-1.136 mg g-1 for NIP, whereas the selectivity values ranged from 1.12-2.4. A kinetic study revealed that adsorption obeys a second-order rate, and the Langmuir model explains adsorption isotherm data. This work showed that the multi-template approach for all the target compounds has the potential to give maximum extraction efficiencies in MIP extraction systems from aqueous samples.

A Facile Highly Selective Anti‐Markovnikov Hydroamination of Vinyl Pyridines by Free Radical Oxidation

AbstractIn this paper, we report a new and facile protocol for anti‐Markovnikov hydroamination of vinyl pyridines under mild condition. In the presence of organic peroxide, pyridylethylation of a wide variety of aryl/alkyl amines with different substituent and electronic characteristics by intermolecular anti‐Markovnikov hydroamination was successfully carried out. Furthermore, moderate to excellent yields were obtained along with high selectivity through condition optimization. The highest yield of target product can reach 93 % in gram‐scale reaction. On the basis, we proposed a kind of aza‐Michael‐type free radical addition mechanism, which was well supported by deuterium labeling studies and reference experiments.

Orientation control of the hexagonal and lamellar phases in thin block copolymer films using in-plane AC electric field

Lamellar and hexagonal pattern rearrangements in thin films of polystyrene–block–poly(2-vinyl pyridine) and polystyrene–block–poly(4-vinyl pyridine) copolymers simultaneously exposed to an in-plane AC electric field and saturated chloroform vapor are studied with atomic force microscopy and analyzed via the numerical solution of the self-consistent field theory equations. It is demonstrated that the use of AC field with the root-mean-square strength higher than 8 V⋅μm−1 allows one to effectively orient microphase-separated domains along the field direction on the tens of microns scale. At the same time, the AC field considerably lowers the risk of breakdown and eliminates effects related to ionic transport in the presence of solvent vapor. The role of such factors as the exposure time, field strength and frequency is investigated. Theoretical considerations prove the equivalent effect of AC and DC fields on the structure of the copolymer film in a wide frequency range. Self-consistent field theory calculations of the free energy as a function of film thickness make it possible to exactly identify which phase dominates in the film. In particular, an apparent transformation of standing cylinders into long threads aligned in the field direction should be interpreted as the phase transition from the perpendicular to parallel hexagonal phase, which can take place in a certain range of film thicknesses, provided the electric field strength exceeds a certain threshold value. In the case of a perpendicular lamellar phase, the domain orientation along the direction of the electric field is always profitable. The observed morphological rearrangements under an in-plane field, which preserve connectivity between the film surfaces through the domains of the minor copolymer block, can be important for practical applications.

Film Instability Induced by Swelling and Drying.

Poly(2-vinyl pyridine), P2VP, films display a surface pattern of craters in a dried state after being immersed in aqueous solutions containing HAuCl4 and its mixtures with low contents of K2CO3. The morphologies of craters indicate that the formation of craters involves three stages through film blistering and drying: (i) the permeability of water and solutes to swell P2VP films, (ii) partial wetting of liquid droplets near the substrate interface in the presence of the P2VP film, and (iii) evaporation-driven flows. The three stages produce the swelling pressure, Laplace pressure, and interplays among capillary flows, Marangoni flows, and pinning effects, respectively, by which craters of different dimensions and morphologies are obtained. The first stage softens the P2VP films and produces swelling pressure. This stage relies on interactions between AuCl4- ions, water, and protonated P2VP chains. The second stage produces liquid droplets inside the film and near the substrate interface. The surface tensions of those liquid droplets at contact lines deform swollen P2VP films. Changing film thicknesses or substrate types alters craters' lateral dimension and depth. The results indicate that film thicknesses and substrate interface energies influence the shape and dimension of liquid droplets on the substrate interface. The third stage determines morphologies of craters through interplays among capillary flows, Marangoni flows, and pinning/depinning events.

Histidine-mediated dendritic mesoporous magnetic ion-imprinted polymer toward effective and recoverable cadmium removal

In this study, a magnetic dendritic mesoporous silica nanoparticle material (MDMS@MAH-Cd-IIP) was prepared via surface ion-imprinted technique for selective removal of Cd(Ⅱ) from aqueous solution. The material was based on an ion-imprinted copolymers of 4-vinyl pyridine (4-VP) and N-methacryloyl-L-histidine (MAH), a synthesized ligand monomer to complex with cadmium ions as ion recognition layer. The obtained polymer was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and magnetic measurement system. The adsorption experiments exhibited MDMS@MAH-Cd-IIP showed fast (within 35 min) and selective capture of Cd(Ⅱ) with maximum uptake capacity of 21.04 mg g−1. The adsorption process followed pseudo-second order kinetic and Langmuir adsorption isotherm models, indicating monolayer chemisorption on homogeneous sites was the rate-limiting step. Meanwhile, the MDMS@MAH-Cd-IIP also showed a specificity recognition ability for Cd(Ⅱ) using analogues Co(Ⅱ), Pb(Ⅱ), Zn(Ⅱ) and Ni(Ⅱ) as interference. Moreover, the MDMS@MAH-Cd-IIP based magnetic SPE can extract approximately 90.0–102.0% of Cd (Ⅱ) in real water samples with a RSD of 3.34–8.23%, which indicated the polymer had the high stability and reproducibility and presented itself a promising material for the Cd(Ⅱ) adsorption and detection from aqueous solution.

Role of Competitive Crystallization Kinetics in the Formation of 2D Platelets with Distinct Coronal Surface Patterns via Seeded Growth.

Low dispersity 2D platelet micelles with controllable surface patterns were prepared by seeded-growth/living crystallization-driven self-assembly (CDSA) of block copolymer/homopolymer (BCP/HP) blends of poly(ferrocenyldimethylsilane)-b-poly(2-vinyl pyridine) (PFS-b-P2VP) and PFS. The precise morphology was found to be dependent on the proportion of the P2VP corona block, which can be efficiently controlled by changing the molar concentration ratio of PFS-b-P2VP/PFS, (cB/cH)t, as well as their relative rates of crystallization, (GB/GH)t. In the case where their molar concentration ratio was comparable to their crystallization rate ratio, platelets with a uniform distribution of P2VP coronal chains were formed. In other cases, as the concentration ratio increased (or decreased) during the living CDSA process, hierarchical structures were formed, including chain-like assemblies consisting of end-to-end linked rectangular platelets and fusiform (tapered) micelles. (GB/GH)t was adjusted by tuning the degree of polymerization of the crystallizable PFS core-forming block and the BCP block ratio and by varying the terminus of the HP or changing the solvent used. Furthermore, the open edge of the platelets remained active for further growth, which permitted control of the morphology and dimensions of the platelets. Interestingly, in cases where the molar concentration ratio was lower than the crystallization rate ratio, growth rings were observed after two or more living CDSA steps. This study on the formation of platelet micelles by living CDSA of BCP/HP blends under kinetic control offers a considerable scope for the design of 2D polymer nanomaterials with controlled shape and surface patterns.

Influence of Carbon Dioxide on the Glass Transition of Styrenic and Vinyl Pyridine Polymers: Comparison of Calorimetric, Creep, and Rheological Experiments

The glass transition of amorphous polymers determines the mobility of polymer chains and the time scale of relaxation processes. The glass transition temperature is reduced by the presence of low molecular weight molecules, e.g., dissolved gases or organic solvents. The quantitative knowledge of reduction of the glass transition temperature caused by the addition of carbon dioxide in a polymer melt is highly relevant for foam extrusion. However, measurement of the reduction of glass transition temperature caused by gas loading has to be performed under elevated pressure which implies high experimental efforts. In this work, we discuss and compare three methods for determination of the influence of carbon dioxide on thermal properties of amorphous polymers, i.e., calorimetric measurements, creep tests, and rheological experiments. The advantages and disadvantages of these methods are elucidated. Furthermore, the influence of molecular structure of the styrenic and vinylpyridine polymers on the glass transition temperature is discussed. Polystyrene generally shows the highest reduction of glass transition temperature. Poly(2-vinylpyridine) and poly(4-vinylpyridine) show a slightly less pronounced behaviour in comparison to polystyrene because of the lower polarity of polystyrene. Poly(α-methyl styrene) is associated with a different dependence of glass transition temperature on gas loading in calorimetric and rheological experiments.

Self-aggregating behavior of poly(4-vinyl pyridine) and the potential in mitigating sand production based on π-π stacking interaction

Unconsolidated sandstone reservoirs are most susceptible to sand production that leads to a dramatic oil production decline. In this study, the poly(4-vinyl pyridine) (P 4 VP) incorporated with self-aggregating behavior was proposed for sand migration control. The P 4 VP could aggregate sand grains spontaneously through π-π stacking interactions to withstand the drag forces sufficiently. The influential factors on the self-aggregating behavior of the P 4 VP were evaluated by adhesion force test. The adsorption as well as desorption behavior of P 4 VP on sand grains was characterized by scanning electron microscopy and adhesion force test at different pH conditions. The result indicated that the pH altered the forms of surface silanol groups on sand grains, which in turn affected the adsorption process of P 4 VP. The spontaneous dimerization of P 4 VP molecules resulting from the π-π stacking interaction was demonstrated by reduced density gradient analysis, which contributed to the self-aggregating behavior and the thermally reversible characteristic of the P 4 VP. Dynamic sand stabilization test revealed that the P 4 VP showed wide pH and temperature ranges of application. The production of sands can be mitigated effectively at 20−130 °C within the pH range of 4–8.

Copper-Induced Fluorescence Quenching in a Bis[2-(2′-hydroxyphenyl)benzoxazole]pyridinium Derivative for Quantification of Cu2+ in Solution

Accurate determination of Cu2+ in solution is crucial for preventing several disease conditions. Spectroscopy-based techniques for metal ion detection are promising methods due to their excellent sensitivity and rapid response time. In this work, we are reporting a newly synthesized 2-(2′-Hydroxyphenyl) benzoxazole-based compound, probe 2, by incorporating a vinyl pyridinium segment into the bis(HBO) 4 system. Probe 2 exhibited excellent specificity toward Cu2+ in solution. The ratiometric absorbance (λ440/λ370) and the quenching of fluorescence at λem ≈585 nm exhibited an excellent linear correlation. The formation of the 2-Cu complex can be utilized as a highly sensitive spectroscopic method for the detection of Cu2+ in solution with a detection limit of 0.15 µM. In addition, Cu2+-induced fluorescence quenching in probe 2 occurs mainly via a static quenching mechanism by forming a 2-Cu complex, and the stability constant for the 2-Cu complex was calculated based on spectroscopic measurements.

Large-area homoporous membranes (HOMEs) enabled by multiple annealing

Homoporous membranes (HOMEs) featuring through pores with almost identical apertures, are highly desired for high-precision separations. It remains a major challenge to produce large-area HOMEs because the microstructure control and defect annihilation become increasingly difficult when membrane sizes are dramatically increased. Herein, we propose a multiple annealing strategy to fabricate large-area HOMEs. Polystyrene-block-poly(2-vinyl pyridine) (PS-b-P2VP) films are first coated on smooth and large substrates. Being annealed by chloroform vapor, perpendicularly aligned P2VP cylinders are formed within the films, and further converted into through pores via the mechanism of selective swelling-induced pore generation. It is shown that the conventional single-time annealing is inadequate to create the ordered through pores, because P2VP chains may have no sufficient time to locomote to the right position as required for the ideal hexagonally arranged ordering. By virtue of the multiple annealing, well-defined through pores can be generated after consecutive annealing for three times, as more P2VP chains aggregate into the ideally ordering position. The films are transferred and composited onto macroporous substrates, producing composite membranes with an effective area of up to ∼100 cm2. The resultant membranes exhibit excellent separation performances. Importantly, HOMEs can be fabricated on low-cost substrates via this strategy, highlighting their great promise in real-world applications of high-precision separations.

Insight into the Evolution of Ordered Mesoporous sp2 Carbonaceous Material Derived from Self-Assembly of a Block Copolymer.

Block-copolymer-derived ordered mesoporous carbon (OMC) materials have great potential in many applications, such as adsorption, catalysis, and energy conversions; however, their formation process and the kinetic mechanism remain unclear. Herein, a N-doped OMC (N-OMC) with sp2-bonded C atoms is developed via self-assembly of the polystyrene-block-poly(4-vinyl pyridine) block copolymer. By correlating the external morphologies with the internal chemical states, the formation process can be concluded as follows: (1) pore evolution via polystyrene domain degradation and (2) regularization and graphitization of the residual carbon via the removal of sp3 C atoms. In addition, the thickness of the N-OMC shows a power function relationship with the spin-coating rate, and the N content can be incredibly increased up to 26.34 at. % in an NH3 carbonization atmosphere. With the as-prepared N-OMC as the support for loading of the pseudo-atomic-scale Pt (Pt/N-OMC), a high electrochemical active surface area value of 99.64 m2·g-1 and a half-wave potential (E1/2) of 0.850 VRHE are achieved, showing great potential in developing single-atom electrocatalysts.

New Hybrid Nanocomposites with Catalytic Properties Obtained by In Situ Preparation of Gold Nanoparticles on Poly (Ionic Liquid)/Poly (4-Vinylpyridine) Nanofibers.

In this work, we report the obtaining of new hybrid nanocomposites with catalytic activity formed by nanofibers of polymer blends and gold nanoparticles. The nanofibers were obtained by electrospinning blends of a poly (ionic liquid) (PIL) and its precursor polymer, poly (4-vinyl pyridine) (P4VPy). The characteristics of the nanofibers obtained proved to be dependent on the proportion of polymer in the blends. The nanofibers obtained were used to synthesize, in situ, gold nanoparticles on their surface by two-step procedure. Firstly, the adsorption of precursor ions on the nanofibers and then their reduction with sodium borohydride to generate gold nanoparticles. The results indicated a significant improvement in the performance of PIL-containing nanofibers over pure P4VPy NFs during ion adsorption, reaching a 20% increase in the amount of adsorbed ions and a 6-fold increase in the respective adsorption constant. The catalytic performance of the obtained hybrid systems in the reduction reaction of 4-nitrophenol to 4-aminophenol was studied. Higher catalytic conversions were obtained using the hybrid nanofibers containing PIL and gold nanoparticles achieving a maximum conversion rate of 98%. Remarkably, the highest value of kinetic constant was obtained for the nanofibers with the highest PIL content.

Direct Methenylation of 4-Alkylpyridines Using Eschenmoser’s Salt

Abstract4-Alkylpyridines are converted into conjugated 1,1-disubstituted alkenyl pyridines (vinyl pyridines) upon treatment with excess ethyl chloroformate, triethylamine, and Eschenmoser’s salt. The reaction proceeds under mild conditions via alkylidene dihydropyridine intermediates.

Enhancement of the electrochemical performance of a cathodically coloured organic electrochromic material through the formation of hydrogen bonded supramolecular polymer assembly

Herein, we have developed an H-bonded network polymer architecture with improved crystallinity and photophysical properties through a supramolecular interaction between carboxylic acid-containing perylenebisimide (PBI) cross-linker and poly(4-vinyl pyridine) (P4VP) polymer chains. The H-bonded supramolecular polymers (SMPs) are thoroughly characterized using 1 H NMR, FTIR, XRD, and AFM studies. The XRD reveals higher molecular packing, long-range ordering, and better crystallinity after supramolecular assembly formation, while AFM confirms the fibril and sphere-like nanostructures in the SMP networks with decreased diameters. The long-range ordering and nanoaggregate structures in SMP benefit the network structure for better diffusion of counter ions during the redox reaction of the PBI moieties. The electrochromic (EC) measurements of the films divulge the similar reversible EC colour change of the PBI and SMP films from pristine red to deep violet along with vis-to-NIR electrochromism between the −2 V to +1 V potential sweeping along with the significant improvement of the EC parameters in SMP films compared to pristine PBI film. The colouring time (red to deep violet) is improved by 63% (5.6 s–2.2 s), while the bleaching time (deep violet to red) is speeded up by 51% (8.4 s–4.1 s) along with the increment in colouration efficiency by 50% (52.3 cm 2 /C to 78.1 cm 2 /C). Therefore, this report is very advantageous to deliver a simple and viable strategy for the enhancement of the EC parameters of organic electrochromes through the generation of ordered H-bonded polymer network formation. • Generation of H-bonded supramolecular polymer assembly (SPA) with perylene bisimide (PBI). • PBI used as cross-linker for H-bonded SPA with poly(4-vinyl pyridine). • SPA shows fast switching and improved colouration efficiency than pristine PBI. • Durable vis-to-NIR electrochromism in PBI based SPA.

Density Functional Theoretical Computational Studies on 3-Methyl 2-Vinyl Pyridinium Phosphate

The molecular structure of 3-methyl 2-vinyl pyridinium phosphate (3M2VPP) has been optimized by using Density Functional Theory using B3LYP hybrid functional with 6-311++G (d, p) basis set in order to find the whole characteristics of the molecular complex. The theoretical structural parameters such as bond length, bond angle, and dihedral angle are determined by DFT methods and are well agreed with the single crystal X-ray diffraction parameters. Theoretical vibrational, highest occupied molecular orbital - lowest unoccupied molecular orbital (HOMO-LUMO), natural bonding orbital (NBO), and electrostatic potential (ESP) analyses have also been performed. Based on the potential energy distribution (PED), the complete vibrational assignments, analysis, and correlation of the compound’s fundamental modes have been determined. Natural bonding orbital (NBO) analysis is used to evaluate the intramolecular charge transfer and hyper-conjugative interaction of the molecule. B3LYP/6-311++G (d, p) basis set determines the electronic properties such as HOMO–LUMO energies and is used to understand the kinetic stability and chemical reactivity of the studied compound. Molecular electrostatic potential (MEP) is used to investigate the electron density distribution and chemical reactive sites of 3M2VPP. The dipole moment, total polarizability, and the first-order hyperpolarizability calculations have been carried out for the studied molecule. Hirshfeld surface analysis has been done to study the intermolecular interactions in the studied complex.

Protein coronas coating polymer-stabilized silver nanocolloids attenuate cytotoxicity with minor effects on antimicrobial performance

Silver nanoparticles are versatile platforms with a variety of applications in the biomedical field. In this framework, their presence in biological media inevitably leads to the interaction with proteins thus conducting to the formation of biomolecular coronas. This feature alters the identity of the nanomaterial and may affect many biological events. These considerations motivated the investigation of protein adsorption onto the surface of polymer-stabilized AgNPs. The metallic colloids were coated by polyethyleneimine (PEI), polyvinylpyrrolidone (PVP), and poly(2-vinyl pyridine)-b-poly(ethylene oxide) (PEO-b-P2VP), and nanoparticle-protein interaction was probed by using a library of analytical techniques. The experimental data revealed a higher extent of protein adsorption at the surface of AgNPs@PVP whereas PEO-b-P2VP coating conducted to the least amount. The main component of the protein coronas was evidenced to be bovine serum albumin (BSA), which is indeed the protein at the highest abundancy in the model biological media. We have further demonstrated reduced cytotoxicity of the silver colloids coated by biomolecular coronas as compared to the pristine counterparts. Nevertheless, the protein coatings did not notably reduce the antimicrobial performance of the polymer-stabilized AgNPs. Accordingly, although the protein-repelling property is frequently targeted towards longer in vivo circulation of nanoparticles, we herein underline that protein coatings, which are commonly treated as artifacts to be avoided, may indeed enhance the biological performance of nanomaterials. These findings are expected to be highly relevant in the design of polymer-stabilized metallic colloids intended to be used in healthcare.

Pseudo-mercaptoethyl pyridine functionalized polyhedral oligomeric silsesquioxane-graphene composite via thiol-ene click reaction for highly selective purification of antibody

In this work, we prepared a novel graphene-based composite by combination of mercapto-end capped polyhedral oligomeric silsesquioxane (POSS-SH) with graphene oxide (GO) through covalent bonding process. The composite was further conjugated with 4-vinyl pyridine (4-VP) through thiol-ene click reaction to fabricate pseudo-mercaptoethyl pyridine functionalized POSS-graphene composite (G-POSS-S-VP). The physicochemical properties were confirmed via FT-IR, TGA, XPS, and TEM characterizations and a high ligand density of ca. 87.3 μmol m−2 was obtained. G-POSS-S-VP composite displayed high selectivity toward antibody, i.e., immunoglobulin G (IgG) in this case based on the hydrophobic charge induced chromatography (HCIC) mechanism. A high adsorption efficiency of ca. 90% and large adsorption capacity of 500 mg g−1 were achieved for IgG at pH 7.4. At the same time, the non-specific adsorptions of co-existing proteins on graphene substrate were obviously hindered. The practical applicability of G-POSS-S-VP composite as adsorbent was verified by selective separation of IgG from human serum. SDS-PAGE assay and MALDI-TOF-MS analysis clearly demonstrated the successful isolation of IgG with high purity.