Core-Corona Magnetic Nanospheres Functionalized with Zwitterionic Polymer Ionic Liquid for Highly Selective Isolation of Glycoprotein.

A novel zwitterionic polymer ionic liquid functionalized magnetic nanospheres, shortly as Fe3O4@PCL-PILs, is synthesized by grafting ionic liquid VimCOOHBr onto polymer ε-caprolactone (PCL) modified magnetic nanospheres via esterification and surface-initiated free radical polymerization. This established synthesis strategy offers the obtained magnetic nanospheres with well-defined core-corona structure, compact grafting layer, favorable zwitterionic and negative-charged surface, and high magnetic susceptibility. The as-prepared Fe3O4@PCL-PILs nanospheres exhibit typical "zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC)" behaviors toward protein binding, and selectively adsorption of glycoprotein is achieved. The adsorption capacity of the magnetic nanospheres toward Immunoglobulin G is high up to 1136.4 mg g-1, and the captured Immunoglobulin G could be efficiently recovered by using 0.5% NH3 H2O (v/v) as stripping reagent, providing a recovery of 80.5%. Fe3O4@PCL-PILs nanospheres are then employed as sorbent for the selective isolation of Immunoglobulin G from human whole blood, obtaining high-purity Immunoglobulin G as demonstrated by polyacrylamide gel electrophoresis assays.

Selective isolation of hemoglobin by use of imidazolium-modified polystyrene as extractant.

Ionic liquids have attracted much attention in the analysis of a variety of species. The functional groups in ionic liquids can result in highly efficient separation and enrichment and, because of their typical lack of volatility, they are environmentally benign. We grafted imidazole cations onto the surface of chloromethyl polystyrene, denoted PS-CH2-[MIM](+)Cl(-), and this modified polymer was used to selectively extract the protein hemoglobin (Hb). The prepared extractant PS-CH2-[MIM](+)Cl(-), containing 2 mmol immobilized imidazole groups per gram polymer, was characterized by FT-IR, surface charge analysis, and elemental analysis. The adsorption efficiency was 91%. The adsorption capacity of the PS-CH2-[MIM](+)Cl(-) for Hb was 23.6 µg mg(-1), and 80% of the retained Hb could be readily recovered by use of 0.5% (m/v) aqueous sodium dodecyl sulfate (SDS) solution as eluate. The activity of the eluted Hb was approximately 90%. The prepared imidazole-containing solid phase polymer was used for direct adsorption of Hb without use of any other solid matrix as support of the ionic liquid. The material was used in practice to isolate Hb from human whole blood.

Photoreversible DNA nanoswitch-based eluent-free strategy for the direct and effective isolation of highly-active thrombin from whole blood.

This study proposes an eluent-free isolation strategy for the direct isolation of thrombin from whole blood via tandem temperature/pH dual-responsive polyether sulfone monolith and photoreversible DNA nanoswitch-functionalized metal-organic framework (MOF) aerogel. Temperature/pH dual-responsive microgel immobilized on polyether sulfone monolith was adopted to remove the matrix complexity of blood sample via size/charge screening effect. Photoreversible DNA nanoswitches, comprising thrombin aptamer, aptamer complementary ssDNA (cDNA) and the azobenzene-modified ssDNA (control DNA), were functionalized on MOF aerogel to offer efficient capturing of thrombin under irradiation of ultraviolet light (365 nm), driven by electrostatic and hydrogen bond interactions. The release of captured thrombin was easily achieved by changing the complementary behaviors of DNA strands via blue light (450 nm) irradiation. Thrombin with purity higher than 95 % can be directly obtained from whole blood using this tandem isolation procedure. Fibrin production and substrate chromogenic tests showed that the released thrombin possessed high biological activity. The photoreversible thrombin capturing-release strategy is merited with eluent-free, avoiding the loss of activity of thrombin in chemical circumstances and undesired dilution, providing a robust guarantee for subsequent application.

A pH-responsive poly(N-isopropylacrylamide-co-acrylic acid) hydrogel for the selective isolation of hemoglobin from human blood.

A pH-responsive poly(N-isopropylacrylamide-co-acrylic acid) hydrogel was prepared by an aqueous dispersion polymerization process. The number of carboxylic groups distributed on the surface of the hydrogel was found to be 1.89 mmol g(-1). The hydrogel exhibits excellent binding selectivity to the protein species of interest within certain pH regions. In the present work, it was applied to the selective isolation of hemoglobin from human whole blood. Some important experimental parameters governing the sorption property, including the pH of sample solution, the ionic strength and sorption time, were investigated. Using 2.0 mg of the hydrogel as a sorption medium and suitable acidity of pH 6.0, a sorption efficiency of 93% was achieved for 200 microg mL(-1) of hemoglobin in 1.0 mL of sample solution. Afterwards, the absorbed hemoglobin could be readily recovered using 1.0 mL of Tris-HCl buffer (pH 8.6, 0.01 mol L(-1)), giving rise to recovery of ca. 76%. The practical applicability of this system was further demonstrated by processing human whole blood for the isolation of hemoglobin, and satisfactory results were obtained by assay with SDS-PAGE.

PEGylation of metal-organic framework for selective isolation of glycoprotein immunoglobulin G.

Metal-organic frameworks (MOFs) have been gaining extensive popularity in the field of sample pretreatment due to their designable structures and easy-modifiable surfaces. Herein, zirconium-based MOFs UiO-66-NH2 is first coated with graphene oxide (GO) layer to enhance the stability, and then grafted with hydrophilic polyethylene glycol (PEG) via amidation reaction to give a product of hydrophilic MOF-based nanomaterial UiO@GO@PEG. The obtained nanoparticles exhibit typical hydrophilic interaction liquid chromatography (HILIC) behavior towards glycoproteins, making itself powerful adsorbent for the extraction of glycoproteins from complex matrices. Under pH 9.0, an adsorption capacity of 139.6 mg g-1 for glycoprotein immunoglobulin G (IgG) is achieved, and the retained IgG could be recovered by 0.5% (m/v) ammonium hydroxide (NH4OH) as stripping reagent with a recovery rate of 82.6%. Moreover, the UiO@GO@PEG shows excellent reusability in IgG isolation. The practicability of UiO@GO@PEG is verified by the selective isolation of IgG from human serum, demonstrating the purity of isolated IgG with SDS-PAGE assay.

Carbon dots with tunable dual emissions: from the mechanism to the specific imaging of endoplasmic reticulum polarity.

Regulating the fluorescence of carbon dots (CDs) is important but highly challenging. Here, carbon dots with tunable dual emissions were facilely fabricated via modulating the polymerization and carbonization processes of o-phenylenediamine (OPD) with lysine (Lys) as the co-precursor and modulator, respectively. The self-polymerization/carbonization of the OPD molecules contributed to the blue/green emission of the OPD-derived CDs. The introduction of Lys in the CD fabrication process efficiently suppressed the carbonization of the OPD polymer chains and enhanced the self-polymerization of the OPD molecules. Meanwhile, the formed OPD-Lys co-polymer chains endowed the final CD product with a new green emission center. The dual-emissive CDs were distinctly sensitive to polarity fluctuations, providing a ratiometric fluorescence response towards solution polarity. Due to their specific distribution in the endoplasmic reticulum (ER), the as-prepared dual-emissive CDs successfully distinguished the polarity variations in ER under stress, which offers a new approach for the early diagnosis of cell injury.

The structure-activity relationship of hydrophilic carbon dots regulated by the nature of precursor ionic liquids.

The preparation of hydrophilic carbon dots (HCDs) with imidazolium dicyanamide ionic liquids (ILs) as precursor revealed a unique structure-activity relationship for the IL-HCDs. Their hydrophilicity, fluorescence nature and cytotoxicity are closely correlated to the alkyl side chain length of the imidazolium cationic moiety. (1) The hydrophilicity of the precursor ILs decreases with the alkyl chain length of their imidazolium cations (from ethyl, butyl, hexyl, octyl to decyl). On the contrary, that of the IL-HCDs increases with the alkyl chain length due to the emergence of COC, NH2 moiety. (2) The passivation effect of alkyl chain plays a dominative role in the enhancement of quantum yield (QY, from 4.6% to 48.0%) of IL-HCDs. The doping of nitrogen-containing moieties contributes marginally. (3) The increase of alkyl chain length leads to the weakening of IL-HCDs/bovine serum albumin (BSA) affinity with a decrease on the quenching constants from 12.59 × 104 to 1.779 × 104 L mol-1. (4) The cytotoxicity of IL-HCDs increases with the length of alkyl chain in the imidazolium cation, though the hydrophilicity of IL-HCDs is increased. In addition, the cytotoxicity of IL-HCDs/BSA is lower than that of IL-HCDs. The protective effect of BSA in the IL-HCDs/BSA 'protein corona' could be utilized to improve the biocompatibility of IL-HCDs.

A magnetic polypyrrole/iron oxide core/gold shell nanocomposite for multimodal imaging and photothermal cancer therapy.

For the purpose of improving the diagnosis and enhancing the photothermal therapeutic effect for cancer under near-infrared (NIR) laser irradiation, a novel magnetic therapeutic platform containing dual photothermal agents, polypyrrole (PPy) and gold nanoshell, is constructed. The nanostructure is composed of a magnetic PPy/Fe3O4-core and a gold nanoshell, which is capable of enhancing the contrast for both magnetic resonance (MR) and X-ray computed tomography (CT) imaging. By attaching Raman probes onto the surface of gold shell, the nanocomposites exhibit the potential to serve as surface-enhanced Raman scattering (SERS) active substrates for optical modality identification of cancer cell. The capability of the therapeutic nanoplatform as photothermal agent is further demonstrated by effective ablation of cancer cells upon exposure to NIR laser at 808nm, which is highly promising for multimodal imaging-guided cancer treatment.

Polyethyleneimine-iron phosphate nanocomposite as a promising adsorbent for the isolation of DNA.

A polyethyleneimine (PEI)-iron phosphate (FePO4) nanocomposite is prepared by immobilization of PEI onto the surface of FePO4 nanoparticles via electrostatic interaction. The obtained PEI-FePO4 nanocomposites are spherical with a size centered in ca. 100 nm. They provide a novel adsorbent for the solid-phase extraction of DNA from complex sample matrices. At pH 4, 50 µg mL(-1) of DNA (salmon sperm DNA sodium salt) in 1.0 mL aqueous solution are quantitatively adsorbed (100%) by 2mg of the PEI-FePO4 nanocomposites, and meanwhile the coexisting albumin at a same concentration level is not retained, demonstrating the favorable selectivity of the nanocomposites to DNA against proteins. The adsorption behaviors of DNA onto the PEI-FePO4 nanocomposites fit Langmuir model, corresponding to an adsorption capacity of 61.88 mg g(-1). The adsorbed DNA could be readily recovered by using a 0.04 mol L(-1) Britton-Robinson (BR) buffer at pH 10, resulting in a recovery of 85%. The nanocomposites have been further used for the isolation of DNA from a series of real sample matrices, including synthetic λ-DNA sample, human whole blood and Escherichia coli cell lysate. The extraction efficiency and the purity of the recovered DNA are at least comparable to those achieved by using the reported sorbent materials or commercial kits. In addition, the DNAs isolated from human whole blood and E. coli cell lysate are of high quality, which have been further demonstrated by using them as templates for successful PCR amplifications.

Novel polymeric ionic liquid microspheres with high exchange capacity for fast extraction of plasmid DNA.

A novel polymeric ionic liquid (PIL) microsphere, poly(1-vinyl-3-(2-methoxy-2-oxyl ethyl)imidazolium) hexafluorophosphate, is prepared via W/O emulsion polymerization. Rapid ion-exchange between the anionic moieties of PIL and DNA fragments is demonstrated facilitating the exchange equilibrium to be reached within 1 min. The PIL microspheres exhibit a high capacity of 190.7 µg mg(-1) for DNA adsorption. A fast DNA isolation protocol is thus developed with the PIL microspheres as solid phase adsorbent. It is feasible to facilitate DNA adsorption or stripping from the microspheres by simply regulating the concentration of salt. DNA adsorption is facilitated at low salt concentration, while higher concentration of salt entails DNA recovery from the microspheres. In practice, the retained DNA could be readily recovered with 1.0 mol L(-1) NaCl as stripping reagent, giving rise to a recovery of ca. 80.7%. The PIL microspheres are used for the adsorption/isolation of plasmid DNA from E. coli cell culture, demonstrating a superior adsorption performance with respect to that achieved by a commercial Plasmid Miniprep Kit.

Fluorescence enhancement of imidazolium ionic liquid by its confinement on PVC for in situ selective quantification of hemoglobin.

A hydrophilic ionic liquid (methylimidazolium chloride, NmimCl)-polyvinyl chloride ionomer (NmimCl-PVC) was prepared by immobilizing and confining N-methylimidazole onto PVC chains. The NmimCl-PVC ionomer exhibits a 4-fold enhancement on the fluorescence intensity with respect to that of NmimCl, attributing to the confinement of ionic liquid by the PVC chain. The fluorescence is excitation-dependent with a maximum at λem 430 nm when excited at 325 nm. In addition, the fluorescence intensity of NmimCl-PVC ionomer increases remarkably with the loading ratio of N-methylimidazole in the range of 4.3-15.1%. The fluorescence quantum yield and lifetime were derived to be 0.112/7.1 ns for the NmimCl-PVC ionomer and 0.063/8.8 ns for NmimCl. Furthermore, hemoglobin is selectively adsorbed by NmimCl-PVC and causes significant fluorescence quenching of the ionomer via dynamic quenching and energy transfer between NmimCl-PVC and hemoglobin. A solid surface fluorimetric procedure was developed for surface adsorption and preconcentration of hemoglobin followed by in situ detection. A linear dynamic range of 0.3-26.2 µg mg(-1) is achieved with a detection limit of 0.1 µg mg(-1). Regarding hemoglobin in aqueous solution, the linear range 5-300 µg mL(-1) is achieved along with a detection limit of 2 µg mL(-1).

Ionic liquid-polyvinyl chloride ionomer for highly selective isolation of basic proteins.

Hydrophilic ionic liquid-polyvinyl chloride (PVC) hybrids were prepared by immobilizing N-methylimidazole (N-mim) to PVC chains in toluene. The NmimCl-PVC hybrids were characterized by FT-IR, (1)H NMR, surface charge analysis and elemental analysis. The immobilization ratio, i.e., the percentage of chloride on PVC chain reacting with N-mim to form the hybrid, varies from 4.3% to 15.1% by increasing the N-mim/PVC molar ratio. The most distinct feature of the hybrid is its excellent selectivity for adsorbing basic proteins by effective suppression of the non-specific protein adsorption by pure PVC, and a higher immobilization ratio facilitates better selectivity. In Tris-HCl buffer, 100 microg mL(-1) of basic proteins, i.e., lysozyme (Lys), cytochrome c (cyt-c) and hemoglobin (Hb), were favorably adsorbed with efficiencies of 97%, 98% and 94% by the hybrid with an immobilization ratio of 15.1%, while the adsorption of acidic proteins, i.e., bovine albumin serum (BSA), transferring (Trf) and immunoglobulin G (IgG) were negligible. The retained Lys, cyt-c and Hb could be readily recovered by elution with phosphate buffer, carbonate buffer and SDS solution with efficiencies of 89%, 87% and 84%, respectively. Another feature of the hybrid is the significant improvement of the biocompatibility characterized by the maintenance of the activity of hemoglobin after adsorption and elution process. The practical usefulness of the hybrid was demonstrated by selective isolation of hemoglobin from human whole blood.

Functionalization of MWNTs with hyperbranched PEI for highly selective isolation of BSA.

Cationic hyperbranched BPEI was immobilized on the surface of MWNTs via electrostatic interactions between the positively charged protonated amines within the polymer and the carboxyl groups on the chemically oxidized MWNT surface. The functionalized BPEI-MWNTs were characterized by FT-IR, TGA, TEM and surface charge analysis, and it was used as a bio-sorbent for the adsorption of proteins. CD spectra showed no conformational change of BSA during the adsorption/desorption process. A dynamic adsorption capacity of 167 mg · g⁻¹ for BSA was achieved. With a sample volume of 2.0 mL, an enrichment factor of 10 was obtained along with an adsorption efficiency of 100%, a recovery of 100%, a sampling frequency of 10 h⁻¹ and a RSD of 2.6% at 25 µg · mL⁻¹ BSA.