Molecularly Imprinted Polymers with Shape-Memorable Imprint Cavities for Efficient Separation of Hemoglobin from Blood.

Efficient separation and purification of hemoglobin from blood and other complicated biological fluids still remains a big challenge. Molecularly imprinted polymers (MIPs) of hemoglobin are potential choices; however, they suffer from severe problems including difficult template removal and low imprinting efficiency like other protein-imprinted polymers. Herein, a novel MIP of bovine hemoglobin (BHb) was designed in which a peptide crosslinker (PC), instead of the commonly used crosslinkers, was used. The PC, a random copolymer of lysine and alanine, adopts an α-helical conformation at pH 10 but transits to a random coil conformation at pH 5. The introduction of alanine residues lowers the pH range at which the PC undergoes helix-coil transition. The imprint cavities in the polymers are shape-memorable due to the reversible and precise helix-coil transition of the peptide segments in the polymers. They can be enlarged by lowering pH from 10 to 5, thus allowing complete removal of the template protein under mild conditions. When the pH is adjusted back to 10, their original size and shape will be recovered. Therefore, the MIP binds the template protein BHb with high affinity. Compared with the MIP crosslinked with the commonly used crosslinker, the imprinting efficiency of the PC-crosslinked MIP is significantly improved. In addition, both the maximum adsorption capacity (641.9 mg/g) and imprinting factor (7.2) are much higher than the BHb MIPs reported previously. The new BHb MIP also exhibits high selectivity toward BHb and good reusability. Thanks to the high adsorption capacity and high selectivity of the MIP, when it was applied to extract BHb from bovine blood, BHb in the blood sample was extracted almost completely, and high purity product was obtained.

Peptide-crosslinked molecularly imprinted polymers for efficient separation of immunoglobulin G from human serum.

Low-cost and highly effective methods are highly desirable to replace the costly ethanol fractionation and affinity chromatography in IgG isolation from human plasma. Molecularly imprinted polymers (MIPs) of IgG are potential candidates, however, they still suffer from severe problems such as difficult template removal and low imprinting efficiency. Here, a recently developed strategy was adopted to overcome these problems. The MIPs were synthesized using poly(L-glutamic acid) (PLGA) peptide crosslinkers instead of commonly used crosslinkers, such as N,N-methylenebisacrylamide (BIS). Because of the pH-induced helix-coil transition and the precise folding of the peptide segments in the polymers, the imprint cavities can be enlarged by adjusting the pH from 5.0 to 7.0, but their original size and shape are restored when the pH is adjusted back. Therefore, the IgG template can be eluted completely under mild conditions, and significantly improved imprinting efficiency can be achieved. Compared with BIS-crosslinked MIP, 8.6 times more binding sites can be created by molecular imprinting PLGA-crosslinked MIP. The factors influencing the performance of the MIP were studied systematically. An optimized MIP with a high adsorption capacity (612.5 mg g-1), high IF (4.92), and high selectivity was obtained. The adsorption capacity and selectivity of the MIP are much higher than the previously reported IgG MIPs. Because of its high adsorption capacity and selectivity, it can separate IgG from human serum effectively, affording high purity products.

Synthesis of carbon-dots@SiO2@TiO2 nanoplatform for photothermal imaging induced multimodal synergistic antitumor.

For facilitating theranostic nanoplatform with multimodal therapeutic ability, we develop the core-shell structured CDs@SiO2@TiO2 nanoplatforms (CST NPs). The designed CST NPs possess excellent photothermal effect and fluorescence resonance energy transfer (FRET) induced photodynamic property, which could achieve synergistic photothermal and photodynamic therapy. Meanwhile, the photothermal ability of CST NPs acts as a key role in the application of real-time photothermal imaging, benefitting for the diagnosis of tumor accurately. Moreover, the obtained CST NPs also exhibit outstanding sonodynamic effect with huge potential for sonodynamic therapy. Under the 650 nm laser irradiation, the synthesized CST NPs not only inhibit the growth of cancer cells in vitro, but also display precise photothermal imaging and photo-induced ablation to tumor in vivo. As a result, the prepared CST NPs may potentially serve as multifunctional nanoplatform for theranostic antitumor and pave the avenue for clinic cancer therapy.

Influence of Cyclodextrins on Thermosensitive and Fluorescent Properties of Pyrenyl-Containing PDMAA.

A series of pyrenyl-containing PDMAA copolymers were prepared by free radical copolymerization of dimethylacrylamide (DMAA) with pyrenebutanoyloxy ethyl methacrylate (PyBEMA). The structure of as-prepared copolymers was characterized by UV, FT-IR and 1H NMR spectroscopy. The effect of cyclodextrins (α-CD, ß-CD and γ-CD) on the thermosensitivity and fluorescence of the copolymers in aqueous solutions were investigated. It was found that the as-prepared copolymers exhibit lower critical solution temperature (LCST)-type thermosensitivity. Cloud point (Tcp) decreases with the increasing molar content of PyBEMA unit in the copolymers. Tcp of the copolymers increases after the CD is added from half molar to equivalent amount relative to pyrenyl moiety, and that further adding twice equivalent CD results in a slight decrease in Tcp. The copolymers exhibit a pyrene emission located at 377 nm and a broad excimer emission centered at 470 nm. The copolymers in water present a stronger excimer emission (Intensity IE) relative to monomer emission (Intensity IM) than that in ethanol. The IE/IM values decrease after the addition of equivalent α-CD, ß-CD and γ-CD into the copolymers in aqueous solution, respectively. The IE/IM values abruptly increase as the copolymers' concentration is over 0.2 mg/L whether in ethanol solution or aqueous solution with or without CD, from which can probably be inferred that intra-polymeric pyrene aggregates dominate for solution concentration below 0.2 mg/L and inter-polymeric pyrene aggregates dominate over 0.2 mg/L. Furthermore, the formation of the CD pseudopolyrotaxanes makes it possible to form pyrene aggregates. For high concentration of 5 g/L, the copolymers and their inclusion complexes completely exhibit an excimer emission. The IE values abruptly increased as the temperature went up to Tcp, which indicates that the IE values can be used to research phase separation of polymers.

Temperature and Recognition Dual Responsive Poly(N-Isopropylacrylamide) and Poly(N,N-Dimethylacrylamide) with Adamantyl Side Group.

A series of copolymers with an adamantyl side group (poly(NIPAM-co-AdMA) and poly(DMAM-co-AdMA)) were prepared by radical copolymerization of N-isopropylacrylamide (NIPAM) and N,N-dimethylacrylamide (DMAM) with a 2-methyl-2-adamantylmethacrylate (AdMA) monomer. The structure and composition of the as-synthesized copolymers were characterized by Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (¹H NMR) spectroscopy, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), and elemental analysis. Temperature and recognition dual responsivity of the copolymers was investigated by cloud point (Tcp) and dynamic light scattering (DLS), respectively. The results show that the as-synthesized copolymers are a kind of temperature-responsive polymer with a lower critical solution temperature (LCST). Tcp was approximately consistent with the critical temperature of intermolecular copolymer association (Tass) from DLS. For these copolymers, Tcp decreases with increasing content of AdMA unit in the copolymers. After the addition of ß-cyclodextrins (ß-CD), Tcp increases, and the increment of Tcp values gradually became large with increasing content of AdMA in the copolymers. It is host-guest molecular recognition of ß-CD and adamantyl groups that endows the as-synthesized copolymers with recognition-tunable thermosensitivity.

Wear and corrosion resistance of Co-P coatings: the effects of current modes.

In this work, Co-P coatings were deposited from a chloride-based bath by direct current (DC), pulse current (PC) and pulse reverse current (PRC) methods, respectively. The effects of current modes on the microstructure, composition, microhardness, wear resistance and corrosion resistance of the Co-P coatings were explored. Results showed that the P content in the Co-P coatings increased and the surface roughness decreased in the sequence of DC, PC and PRC methods. The coatings with low P content deposited by DC and PC methods are crystalline with fcc and hcp structures, respectively, while the coating with high P content deposited by the PRC method is amorphous. Comparing to DC and PC methods, the PRC method can evidently improve the microhardness, wear resistance and corrosion resistance of Co-P coatings. The excellent wear and corrosion resistance of the Co-P coatings deposited by the PRC method could be attributed to its high P content, smooth surface and amorphous structure.