PolyGuanine methacrylate cryogels for ribonucleic acid purification

The isolation and purification of ribonucleic acid have attracted attention recently for the understanding of the functions in detail because of the necessity for the treatment of genetic diseases. In this study, guanine‐incorporated polymeric cryogels were developed to obtain highly purified ribonucleic acid. The satisfactory purification performance was achieved with the guanine‐incorporated poly (2‐hydroxyethyl methacrylate‐guanine methacrylate) cryogels. The most crucial advantages to use guanine as a functional monomer are to obtain a real natural interaction between guanine on the polymeric material and cytosine on the ribonucleic acid. Moreover, using cryogel with a highly porous structure and high swelling ratio provide advantages of getting more water within the structure to get more analyte to interact. The characterization of cryogels has proved the success of the synthesis and the perfect natural interaction to be taken place between the ligand (guanine methacrylate) and the cytosine in the ribonucleic acid molecules. Although the pores within the structure of cryogels are small, they provide efficient and fast adsorption. The chromatographic separation performance was investigated for different conditions (pH, temperature etc.). The desorption ratio and reusability were also analyzed at the end of the five adsorption–desorption cycles with no significant changes.     

Dye attached poly(hydroxyethyl methacrylate) cryogel for albumin depletion from human serum

Cibacron Blue F3GA was immobilized on poly(hydroxyethyl methacrylate) cryogel and it was used for selective and efficient depletion of albumin from human serum. The poly(hydroxyethyl methacrylate) was selected as the basic component because of its inertness, mechanical strength, chemical and biological stability, and biocompatibility. Cibacron Blue F3GA was covalently attached to the poly(hydroxyethyl methacrylate) cryogel to produce poly(hydroxyethyl methacrylate)-Cibacron Blue F3GA cryogel affinity column. The poly(hydroxyethyl methacrylate)-Cibacron Blue F3GA cryogel was characterized with respect to gelation yield, swelling degree, total volume of macropores, Fourier Transform Infrared spectroscopy, and scanning electron microscopy. It was found that the maximum amount of adsorption (343 mg/g of dry cryogel) obtained from experimental results is very close to the calculated Langmuir adsorption capacity (345 mg/g of dry cryogel). The maximum adsorption capacity for poly(hydroxyethyl methacrylate)-Cibacron Blue F3GA cryogel column was obtained as 950 mg/g of dry cryogel for nondiluted serum. The adsorption capacity decreased with increasing dilution ratios while the depletion ratio of albumin remained as 77% in serum sample. Finally, the poly(hydroxyethyl methacrylate)-Cibacron Blue F3GA cryogel was optimized for using in the fast protein liquid chromatography system for rapid removal of the high abundant proteins from the human serum.     

Poly(hydroxyethyl methacrylate)‐based composite cryogel with embedded macroporous cellulose beads for the separation of human serum immunoglobulin and albumin

A novel super‐macroporous monolithic composite cryogel was prepared by embedding macroporous cellulose beads into poly(hydroxyethyl methacrylate) cryogel. The cellulose beads were fabricated by using a microchannel liquid‐flow focusing and cryopolymerization method, while the composite cryogel was prepared by cryogenic radical polymerization of the hydroxyethyl methacrylate monomer with poly(ethylene glycol) diacrylate as cross‐linker together with the cellulose beads. After graft polymerization with (vinylbenzyl)trimethylammonium chloride, the composite cryogel was applied to separate immunoglobulin‐G and albumin from human serum. Immunoglobulin‐G with a mean purity of 83.2% and albumin with a purity of 98% were obtained, indicating the composite cryogel as a promising chromatographic medium in bioseparation for the isolation of important bioactive proteins like immunoglobulins and albumins.     

Molecularly imprinted cryogel as a pH-responsive delivery system for doxorubicin

In this study, implantable and degradable molecularly imprinted cryogel was prepared for pH-responsive delivery of doxorubicin. Cryogel discs were synthesized using amino acid-based functional monomer with HEMA and gelatin. The molecularly imprinted discs were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, degradation and swelling tests. In vitro delivery experiments were carried out in order to examine the effects of medium pH and drug content. The degree of degradation of composite cryogels was found to be 83.45±1.86% after 56 days. The release profiles of DOX from molecularly imprinted cryogel discs exhibit a biphasic delivery. It was observed that an initial burst release step from 0 to 12 h was followed by a slower and sustained release. Release rate of DOX from cryogel discs increased in more acidic conditions. Kinetic studies showed that a combination of diffusion and erosion control is mainly responsible from the general release behaviors of molecularly imprinted cryogel discs.     

Molecularly imprinted supermacroporous cryogels for cytochrome c recognition

Molecular imprinting is an attractive biomimetic approach that creates specific recognition sites for the shape and functional group arrangement to template molecules. The purpose of this study is to prepare cytochrome c-imprinted poly(hydroxyethyl methacrylate) (PHEMA)-based supermacroporous cryogel which can be used for the separation of cytochrome c from protein mixtures. N-Methacryloyl-(L)-histidinemethylester (MAH) was used as the metal-coordinating monomer. In the first step, Cu(2+) was complexed with MAH, and the cytochrome c imprinted PHEMA (MIP) cryogel was prepared by free radical cryopolymerization initiated by N,N,N',N'-tetramethylene diamine at -12°C. After polymerization is completed, the template cytochrome c molecules were removed from the MIP cryogel using 0.5 M NaCl solution. The maximum cytochrome c binding amount was 126 mg/g polymer. Selective binding studies were performed in the presence of lysozyme and bovine serum albumin. The relative selectivity coefficients of MIP cryogel for cytochrome c/lysozyme and cytochrome c/bovine serum albumin were 1.7 and 5.2 times greater than those of the non-imprinted PHEMA cryogel, respectively. The selectivity of MIP cryogel for cytochrome c was also confirmed with fast protein liquid chromatography. The MIP cryogel could be used many times with no remarkable decrease in cytochrome c binding capacity.     

Morphological and mechanical properties of tannic acid/PAAm semi-IPN hydrogels for cell adhesion

A series of hydrogels were fabricated from tannic acid (TA), a typical plant polyphenol widely present in wood, and polyacrylamide (PAAm) by semi-IPN and cryogelation techniques. The introduction of TA into the PAAm network endows the system with enhanced cell adhesion properties. The cryogels with open interconnected macropores had a superfast swelling rate and a high swelling ratio, as well as high elasticity in response to compression. The degradation of the hydrogels can be tuned by modulating the content of cross-linker poly(ethylene glycol) diacrylate (PEGDA). Cytotoxicity results revealed that the hydrogels were non-toxic to COS-7 cells. All these results suggested that TA/PAAm semi-IPN hydrogels have great potential for applications in tissue engineering.     

Biocompatible cryogels of thermosensitive polyglycidol derivatives with ultra-rapid swelling properties

Novel thermosensitive macroporous cryogels, based on various hydrophobically modified high molar mass (HMM) polyglycidol precursors, were synthesized using the UV-irradiation technique. The method involved the preparation of a semi-dilute aqueous solution of thermosensitive poly(glycidol-co-ethyl glycidyl carbamate) (PGL-Et), subsequent freezing at a moderately negative temperature (−20 °C) and irradiation with UV light. All PGL-Et cryogels had a spongy-like structure of smooth polymer walls surrounding interconnected macroscopic pores. Consequently, the cryogels exhibited temperature triggered, reversible, ultra-rapid volume phase transition (VPT) from a swollen to deswollen state within 20–25 s. The VPT temperature of the PGL-Et cryogels was strongly dependent on the degree of modification of the PGL precursors and it decreased proportionally with increased ethyl glycidyl carbamate content. The PGL-Et cryogels were used as a scaffold for skin cell (fibroblast) adhesion. Adhesion and proliferation tests indicated that the gels were good supports for cell cultivation.     

A novel adsorbent for protein chromatography: supermacroporous monolithic cryogel embedded with Cu2+-attached sporopollenin particles

The aim of this study is to prepare supermacroporous cryogels embedded with Cu(2+)-attached sporopollenin particles (Cu(2+)-ASP) having large surface area for high protein adsorption capacity. Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA)-based monolithic cryogel column embedded with Cu(2+)-ASP was prepared by radical cryo-copolymerization of 2-hydroxyethyl methacrylate (HEMA) with N,N'-methylene-bis-acrylamide (MBAAm) as cross-linker directly in a plastic syringe for affinity purification of human serum albumin (HSA). Firstly, Cu(2+) ions were attached to sporopollenin particles (SP), then the supermacroporous PHEMA cryogel with embedded Cu(2+)-ASP was produced by free radical polymerization using N,N,N',N'-tetramethylene diamine (TEMED) and ammonium persulfate (APS) as initiator/activator pair in an ice bath. Embedded particles (10 mg) in PHEMA-based cryogel column were used in the adsorption/desorption of HSA from aqueous solutions. Optimum conditions of adsorption experiments were performed at pH 8.0 phosphate buffer, with flow rate of 0.5 mL/min, and at 5°C. The maximum amount of HSA adsorption from aqueous solution was very high (677.4 mg/g SP) with initial concentration 6 mg/mL. It was observed that HSA could be repeatedly adsorbed and desorbed to the embedded Cu(2+)-ASP in PHEMA cryogel without significant loss of adsorption capacity.