Extensive Imprinting Adaptability of Polyacrylamide-based Amphoteric Cryogels Against Protein Molecules

Sulfolane Crystal Templating: A One-Step and Tunable Polarity Approach for Self-Assembled Super-Macroporous Hydrophobic Monoliths

Freeze-casting (ice templating) is generally used to prepare super-macroporous materials. However, water solubility limits the application of freeze-casting in hydrophobic material fabrication. In the present work, inexpensive and low-toxic sulfolane was used as a novel crystallization-induced porogen (sulfolane crystal templating) to prepare super-macroporous hydrophobic monoliths (cryogels) with tunable polarity. The phase transition of sulfolane consisted of reversible processes in the liquid, semi-crystalline, and crystalline states. Because of the density change during phase transition, liquid sulfolane experienced a 16.4% volume shrinkage per unit mass. Thus, the cryogels obtained using the conventional freezing method contained obvious hollow-shaped defects. Furthermore, a novel route of pre-cooling, pre-crystallization, crystal growth, freezing, and thawing (PPCFT) was employed to prepare cryogels with defect-free macroscopic morphology and uniform pore structure. The as-obtained cryogels were composed of a super-macroporous structures and interconnected channels, and their porosity ranged between 85 and 97%. Moreover, the cryogels manifested good hydrophobicity (contact angle = 120-130°) and had absorption capacities greater than 10 g g^-1 for oils and organic liquids. The maximum absorption capacities of the resultant cryogels in dichloromethane, ethyl acetate, and liquid paraffin were 60.3, 35.8, and 15.2 g g^-1, respectively. Moreover, sulfolane could conveniently dissolve hydrophobic and hydrophilic monomers to generate amphiphilic cryogels (contact angle = 130-0°). Therefore, sulfolane crystal templating is a potential fabrication method for super-macroporous hydrophobic materials with tunable polarity.

Molecular imprinting of bovine serum albumin and lysozyme within the matrix of polyampholyte hydrogels based on acrylamide, sodium salt of 2-acrylamido-2-methyl-1-propanesulfonic acid and (3-acrylamidopropyl)trimethyl ammonium chloride

Molecularly-imprinted polyampholyte (MIP) hydrogels based on nonionic monomer – acrylamide (AAm), anionic monomer – sodium salt of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and cationic monomer – (3-acrylamidopropyl)trimethyl ammonium chloride (APTAC) were obtained by immobilization of bovine serum albumin (BSA) and lysozyme in situ polymerization conditions. It was found that the best amphoteric hydrogel for sorption of BSA is APTAC-75H while for sorption of lysozyme is AMPS-75H. The sorption capacity of APTAC-75H and AMPS-75H with respect to BSA and lysozyme is 305.7 and 64.1-74.8 mg per 1 g of hydrogel respectively. Desorption of BSA and lysozyme from MIP template performed by aqueous solution of 1M NaCl is equal to 82-88%. Separation of BSA and lysozyme from their mixture was performed on MIP templates. The results of adsorption-desorption cycles of BSA on adjusted to BSA polyampholyte hydrogel APTAC-75H and of lysozyme on adjusted to lysozyme polyampholyte hydrogel AMPS-75H show that the mixture of BSA and lysozyme can be selectively separated with the help of MIP hydrogels.

The integration of molecular imprinting and surface-enhanced Raman scattering for highly sensitive detection of lysozyme biomarker aided by density functional theory

Surface-enhanced Raman scattering (SERS) is a powerful bioanalytical technique that opens opportunities for early disease diagnosis and treatment by detecting biomarkers. However, the low sensitivity, selectivity, and reproducibility in the bioanalytical SERS are the main obstacles for clinical use. Herein, we demonstrate a high sensitive and selective label-free lysozyme biomarker detection platform based on coupling of SERS with molecular imprinting technique. The hierarchical silver microspheres with dendritic structure are controllably fabricated by a wet-chemical self-assembly approach. Based on selection of surface-active regions by density functional theory (DFT) simulations, a thin MIPs film (thickness < 15 nm) is then grafted on Ag microsphere surface through surface imprinting. As a result, the final synthesized Ag@MIPs hybrid exhibits as low as 5 ng mL^-1 detection limit for target lysozyme, and high selectivity and reproducibility. Intensive "hot spots" in Ag@MIPs confirmed by Raman mapping give rise to the high-performance SERS. Meanwhile, DFT calculations are employed to investigate the SERS spectra and assist the assignment for the characteristic peaks of lysozyme. We believe that the present study provides a reliable and high-sensitive protocol for label-free protein biomarkers detection.

Physicochemical, Complexation and Catalytic Properties of Polyampholyte Cryogels

Polyampholyte cryogels are a less considered subject in comparison with cryogels based on nonionic, anionic and cationic precursors. This review is devoted to physicochemical behavior, complexation ability and catalytic properties of cryogels based on amphoteric macromolecules. Polyampholyte cryogels are able to exhibit the stimuli-responsive behavior and change the structure and morphology in response to temperature, pH of the medium, ionic strength and water–organic solvents. Moreover, they can uptake transition metal ions, anionic and cationic dyes, ionic surfactants, polyelectrolytes, proteins, and enzymes through formation of coordination bonds, hydrogen bonds, and electrostatic forces. The catalytic properties of polyampholyte cryogels themselves and with immobilized metal nanoparticles suspended are outlined following hydrolysis, transesterification, hydrogenation and oxidation reactions of various substrates. Application of polyampholyte cryogels as a protein-imprinted matrix for separation and purification of biomacromolecules and for sustained release of proteins is demonstrated. Comparative analysis of the behavior of polyampholyte cryogels with nonionic, anionic and cationic precursors is given together with concluding remarks.

Efficient discovery and capture of new neuronal nitric oxide synthase-postsynaptic density protein-95 uncouplers from herbal medicines using magnetic molecularly imprinted polymers as artificial antibodies

In the scope of stroke treatment, new neuronal nitric oxide synthase-postsynaptic density protein-95 uncouplers from herbal medicines were discovered and captured. To do so, highly selective magnetic molecularly imprinted polymers with a core-shell structure were prepared as artificial antibodies. According to the results of computational simulations, we designed and synthesized various polymers with varying amounts and types of template, functional monomer, cross-linker, and solvent. Characterization and performance tests revealed that the most appropriate artificial antibodies showed uniform spherical morphologies, large adsorption capacities, fast-binding kinetics, high selectivity, and quick separation. These artificial antibodies were then used as sorbents for dispersive magnetic solid-phase extraction coupled with high-performance liquid chromatography and mass spectrometry to capture and identify structural analogs to ZL006 from extracts of Scutellariae radix, Psoraleae fructus, and Trifolium pratense. Furthermore, according to the neuroprotective effect and coimmunoprecipitation test, Baicalein, Neobavaisoflavone, Corylifol A, and Biochanin A can be the potential uncouplers of neuronal nitric oxide synthase-postsynaptic density protein-95. Therefore, this present study contributes valuable information for the discovery of neuronal nitric oxide synthase-postsynaptic density protein-95 uncouplers from herbal medicines.

Synthesis of Molecularly Imprinted Cryogels to Deplete Abundant Proteins from Bovine Serum

Molecularly imprinted polyacrylamide cryogels were synthesized with pending templates (bovine serums of different concentrations). As the serum concentrations increased in the monomer solutions, the resulting cryogels could adsorb and deplete more proteins from serum samples. Due to the addition of vinyltriethoxysilane (VTEOS) in the prepolymerizing solutions, the polymers came as organic⁻inorganic hybrid materials. It endued the silica-modified amphoteric polyacrylamide cryogels with improved mechanical strengths. Scanning electron micrography (SEM), Infrared (IR) spectrometry, thermogravimetry-differential thermal analysis (TG-DTA), and X-ray photoelectron spectroscopy (XPS) were carried out to characterize these macroporous polymers. Amphoteric cryogels proved to be favorable materials recognizing and binding proteins. When used as liquid chromatography stationary phases, they were capable of simultaneously adsorbing various serum proteins. Electrophoresis showed that abundant proteins were gradually depleted by the cryogels prepared from increased ratios of bovine serums in the monomer solutions. As abundant proteins are always imprinted first, this sample per se imprinting method provides an effective and convenient way to deplete abundant proteins from complex samples such as serums, meanwhile concentrating and collecting scarce species therein.