Polyethyleneimine assisted-two-step polymerization to develop surface imprinted cryogels for lysozyme purification

Preparation and characterization of lysozyme loaded cryogel for heavy metal removal

In the present study, monolithic poly(N-isopropylacrylamide-acrylamide)-acrilic acid (poly(npam-aam)-aac) cryogels were made. Swelling tests, SEM, XRD, and ATR-FTIR analyses revealed distinct cryogel and lysozyme-loaded cryogel properties. The equilibrium swelling degree was 6.2 g H2O/g cryogel. The created poly(npam-aam)-aac with pores of 10-100 μm was obviously seen in SEM images. Lysozyme adsorption capacity on poly(npam-aam)-aac was found to be 260 mg/g at pH 7.4 and 40 °C. After that, we used lysozyme adsorbed cryogel for the removal of the model heavy metal ion (cadmium). A series of pH, duration, and ionic strengths were used to conduct Cd2+ adsorption experiments. The results showed that the new adsorbent had a considerable chemical affinity for Cd2+ ions in its ability to bind them under eye ocular conditions (pH 7.4, 32-36 °C, 0,15 M NaCl). The traditional Langmuir adsorption model was the most suitable, achieving maximum uptake of ∼185 mg/g. Chemical adsorption was found to be the rate-controlling step, and the process was also compatible with the pseudo-second-order model. For the treatment of ocular pathologies, the most effective enzyme, lysozyme, must show its function. That is why there is a need for using lysozyme, and lysozyme is selected as a lignad to adsorb heavy metal ions because of its high heavy metal binding affinity. This material could be used for the treatment of ocular pathologies in the future.

Magnetic cryogels as a shape-selective and customizable platform for hyperthermia-mediated drug delivery

Cryogels consisting of polyvinyl alcohol and iron (II, III) oxide magnetic nanoparticles coated with a model drug—acetaminophen, were developed as a tunable platform for thermally triggered drug release, based on shape-selective heat transfer. Two different shapes of cryogels; discs and spherical caps, were formed via adding polymer-nanoparticle-drug mixtures into 3D printed molds, followed by freeze-thawing five times. No additional chemical crosslinking agents were used for gel formation and the iron oxide nanoparticles were coated with acetaminophen using only citric acid as a hydrogen-bonding linker. The two gel shapes displayed varying levels of acetaminophen release within 42–50 °C, which are ideal temperatures for hyperthermia induced drug delivery. The amount and time of drug-release were shown to be tunable by changing the temperature of the medium and the shape of the gels, while keeping all other factors (ex. gel volume, surface area, polymer/nanoparticle concentrations and drug-loading) constant. The discs displayed higher drug release at all temperatures while being particularly effective at lower temperatures (42–46 °C), in contrast to the spherical caps, which were more effective at higher temperatures (48–50 °C). Magnetic hyperthermia-mediated thermal imaging and temperature profiling studies revealed starkly different heat transfer behavior from the two shapes of gels. The disc gels retained their structural integrity up to 51 °C, while the spherical caps were stable up to 59 °C, demonstrating shape-dependent robustness. The highly customizable physicochemical features, facile synthesis, biocompatibility and tunable drug release ability of these cryogels offer potential for their application as a low cost, safe and effective platform for hyperthermia-mediated drug delivery, for external applications such as wound care/muscle repair or internal applications such as melanoma treatment.

Molecularly imprinted polymers in toxicology: a literature survey for the last 5 years

The science of toxicology dates back almost to the beginning of human history. Toxic chemicals, which are encountered in different forms, are always among the chemicals that should be investigated in criminal field, environmental application, pharmaceutic, and even industry, where many researches have been carried out studies for years. Almost all of not only drugs but also industrial dyes have toxic side and direct effects. Environmental micropollutants accumulate in the tissues of all living things, especially plants, and show short- or long-term toxic symptoms. Chemicals in forensic science can be known by detecting the effect they cause to the body with the similar mechanism. It is clear that the best tracking tool among analysis methods is molecularly printed polymer-based analytical setups. Different polymeric combinations of molecularly imprinted polymers allow further study on detection or extraction using chromatographic and spectroscopic instruments. In particular, methods used in forensic medicine can detect trace amounts of poison or biological residues on the scene. Molecularly imprinted polymers are still in their infancy and have many variables that need to be developed. In this review, we summarized how molecular imprinted polymers and toxicology intersect and what has been done about molecular imprinted polymers in toxicology by looking at the studies conducted in the last 5 years.

Water-soluble polymeric particle embedded cryogels: Synthesis, characterisation and adsorption of haemoglobin

Making cryogels, which are among today’s accepted adsorbents, more functional with different methods, has been one of the subjects spent overtime. In this study, water-soluble poly(maleic anhydride-alt-acrylic acid) polymer embedded in poly(2-hydroxyethyl methacrylate) cryogels. Copper ions were then immobilised to this structure, and this polymer was used for adsorption of haemoglobin from aqueous systems. Adsorption interaction was carried out on an electrostatic basis, and approximately 448.62 mg haemoglobin/g polymer adsorption capacity value was obtained. It was found that the same material has managed to maintain its adsorption ability by 90.3% even after the use of it five times in the adsorption/desorption cycle. The adsorption interaction was determined to be appropriate for the Langmuir model by isotherm studies. The change in Gibbs free energy value was calculated as −2.168 kJ/mol.

Antimicrobial magnetic poly(GMA) microparticles: synthesis, characterization and lysozyme immobilization

Micron-sized magnetic particles currently find a wide range of applications in many areas including biotechnology, biochemistry, colloid sciences and medicine. In this study, magnetic poly(glycidyl methacrylate) microparticles were synthesized by providing a polymerization around Fe(II)-Ni(II) magnetic double salt. Adsorption of lysozyme protein from aqueous systems was studied with these particles. Adsorption studies were performed with changing pH values, variable amount of adsorbent, different interaction times and lysozyme amounts. The adsorption capacity of the particles was investigated, and a value of about 95.6 mg lysozyme/g microparticle was obtained. The enzyme activity of the immobilized lysozyme was examined and found to be more stable and reusable compared to the free enzyme. The immobilized enzyme still showed 80% activity after five runs and managed to maintain 78% of its initial activity at the end of 60 days. Besides, in the antimicrobial analysis study for six different microorganisms, the minimum inhibitory concentration value of lysozyme immobilized particles was calculated as 125 μg/mL like free lysozyme. Finally, the adsorption interaction was found to be compatible with the Langmuir isotherm model. Accordingly, it can be said that magnetic poly(GMA) microparticles are suitable materials for lysozyme immobilization and immobilized lysozyme can be used in biotechnological studies.

Challenges and Advances in the Fabrication of Monolithic Bioseparation Materials and their Applications in Proteomics Research

High-performance liquid chromatography integrated with tandem mass spectrometry (HPLC-MS/MS) has become a powerful technique for proteomics research. Its performance heavily depends on the separation efficiency of HPLC, which in turn depends on the chromatographic material. As the "heart" of the HPLC system, the chromatographic material is required to achieve excellent column efficiency and fast analysis. Monolithic materials, fabricated as continuous supports with interconnected skeletal structure and flow-through pores, are regarded as an alternative to particle-packed columns. Such materials are featured with easy preparation, fast mass transfer, high porosity, low back pressure, and miniaturization, and are next-generation separation materials for high-throughput proteins and peptides analysis. Herein, the recent progress regarding the fabrication of various monolithic materials is reviewed. Special emphasis is placed on studies of the fabrication of monolithic capillary columns and their applications in separation of biomolecules by capillary liquid chromatography (cLC). The applications of monolithic materials in the digestion, enrichment, and separation of phosphopeptides and glycopeptides from biological samples are also considered. Finally, advances in comprehensive 2D HPLC separations using monolithic columns are also shown.

Preparation and Properties of Cryogel Based on Poly(2-hydroxyethyl methacrylate- co-glycidyl methacrylate)

The immobilized metal affinity cryogels based on poly(2-hydroxyethyl methacrylate- co-glycidyl methacrylate) (p(HEMA-GMA)) containing hydroxy and epoxy groups were prepared by free-radical copolymerization under cryogenic condition and then functionalized with iminodiacetic acid and chelated Cu²⁺, Ca²⁺, and Fe³⁺ ions to the p(HEMA-GMA) cryogel. The structures of p(HEMA-GMA) and immobilized metal-affinity cryogels were analyzed by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy. SEM results showed that the prepared cryogels had interconnected pores with the size of 30-100 μm. The performance of water swelling into the cryogels was fitted in Fickian diffusion. The adsorption property of cryogels was influenced by the immobilized ionic type, temperature, and adsorbate. The adsorption capacity of immobilized Cu²⁺ cryogel (p(HEMA)-Cu²⁺ (0.5 M) cryogel) was the highest in comparison with that of Ca²⁺ and Fe³⁺ affinity cryogels under the same condition. The maximum adsorption capacity of p(HEMA)-Cu²⁺ (0.5 M) cryogel for porcine pancreatic lipase was 150.14 mg/g at a higher temperature of 35 °C, whereas for bovine serum albumin, the maximum adsorption capacity was 154.11 mg/g at a lower temperature of 25 °C. The research of thermodynamics and kinetics indicated that the mechanism of the protein adsorption process corresponded to the Langmuir model and pseudo-second-order model.

Effect of immobilization on the activity of catalase carried by poly(HEMA-GMA) cryogels

Hydrogen peroxide is converted by catalase to molecular oxygen and water to remove oxidative stress. In this study, catalase immobilization was performed using poly(2-hydroxyethyl methacrylate-glycidyl methacrylate) (poly(HEMA-GMA)) cryogels with different amounts of GMA. Catalase adsorption capacity of 298.7 ± 9.9 mg/g was achieved at the end of 9 h using the poly(HEMA-GMA)-250 cryogel. Kinetic parameters and the inhibitory effects of pesticides such as 4,4'-DDE and 4,4'-DDT on the activity of free and immobilized catalase enzyme were investigated. While the V_max value of the immobilized enzyme was reduced 4-fold compared to the free enzyme, in the case of the comparison of the K_M values, the affinity of the immobilized enzyme was increased by 1.94 times against the substrate. The inhibitory effect of 4,4'-DDT pesticide was found to be higher for the immobilized and free enzyme. NaCl (1 M, pH: 7.0) solution was used for desorption of the adsorbed catalase enzyme. A desorption ratio of 96.45% was achieved. The technique used in this study is promising regarding for the immobilization of catalase enzyme to increase the operational activity. Therefore, poly(HEMA-GMA) cryogels have the potential to be used for immobilization of catalase enzyme in the fields of biology and biochemistry.

Selective binding of matrix metalloproteases MMP-9 and MMP-12 to inhibitor-assisted thermolysin-imprinted beads

Protein-imprinted polymers have been synthesized to recognize and specifically bind selected proteins. However, protein imprinting requires substantial amounts of pure protein to efficiently obtain imprinted polymers for large scale applications, e.g. protein purification by affinity chromatography. In the absence of large quantities of a pure protein of interest, an alternative strategy was developed. In this case study, neutral metalloprotease thermolysin was selected as a commercially available surrogate for imprinting polymer beads. Phosphoramidon-assisted thermolysin-imprinted beads were synthesized. During rebinding experiments, it was shown that these beads specifically bind to thermolysin. In addition, it was shown that these beads also bind in CHO cell culture supernatant to the matrix metalloprotease-9 and -12 (MMP-9, -12). Therefore, these beads can be applied as a selective sorbent for the rare metalloproteases MMP-9 and MMP-12 to remove these proteases from CHO cell culture supernatants. The high selectivity of thermolysin-imprinted beads can be extended to other proteases of the family of metalloproteases, and is not limited to thermolysin. This innovative approach is suitable to address the challenges in the field of protease purification and isolation from biotechnologically relevant media.

Solvent effect on endosulfan adsorption onto polymeric arginine-methacrylate cryogels

Endosulfan is a persistent insecticide that is still used in some countries even though it is life-threatening and banned in the agricultural struggle. The solubility of pesticides in water is negligible. It is known that pesticides with better solubility in organic solvents have different solubility when the dielectric constants of these solvents are taken into account. The polymeric structure of arginine was modified with methacrylate to be a functional monomer, and it was immobilized on a solid support, poly(HEMA), and finally, poly(2-hydroxyethyl methacrylate-arginine methacrylate) was obtained and used as an effective adsorbent. The effect of organic solvents on endosulfan adsorption was investigated for the first time in the literature. Endosulfan was removed from alcohol media by using this polymeric structure synthesized by exploiting alcoho-phobic interaction in this work. Nuclear magnetic resonance (NMR), elemental analysis, and Fourier transform infrared spectroscopy (FTIR) methods were used for the structural characterization and therefore to prove successful synthesis of cryogels. Morphological characteristics were also investigated by scanning electron microscopy (SEM), an N₂ adsorption method, and swelling test. Adsorption experiments were carried out against varying interaction time and concentration parameters in the batch system. Since the alcohol used as a solvent has a pH value close to the ionic strength of drinking water, no change was made in the pH of the solution. Endosulfan molecules dissolved in solvents such as toluene, dichloromethane, acetone, and chloroform were removed using poly(HEMA-ArMA) cryogels to determine the solvent effect on the adsorption of endosulfan. As expected, the removal of endosulfan from the solvent toluene provided the best result. Although the adsorption in toluene is almost 9.5 times higher than that in ethanol, the use of toluene in the adsorption process due to its chemical structure is not feasible. Thus, experiments were carried out in ethanol.

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.

Fabrication and evaluation of molecularly imprinted magnetic nanoparticles for selective recognition and magnetic separation of lysozyme in human urine

The Lyz-MMIPs displayed a uniform core–shell structure, favorable magnetic properties, good accessibility, and good stability and had a good affinity and excellent binding selectivity to Lyz.

Removal of DDE by exploiting the alcoho-phobic interactions

DDE (1,1-bis-(4-chlorophenyl)-2,2-dichloroethene), which is a commonly used pesticides in agriculture, has harmful effects on human health. Therefore, the removal of this substance from the drinking water and the soil is essential. Since DDT (1,1″-(2,2,2-Trichloroethane-1,1-diyl) bis(4-chlorobenzene)) is derivation of DDE, the presence of DDT can be monitored by the detection of DDE present in the environment. Herein, we report on the development of aspartic acid-incorporated poly(2-hydroxyethyl methacrylate-L-aspartic acid) [poly(HEMA-MAsp)] cryogel for the removal of DDE from aqueous solutions for the first time in the literature. The synthesized cryogels were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), an N₂ adsorption method, elemental analysis, and swelling test. The separation experiments were carried out via a batch system to get the optimum adsorption conditions including pH, interaction time, initial DDE concentration, and temperature. The desorption and the reusability results revealed that there was no significant decrease in the DDE adsorption capacity of the cryogels after five adsorption-desorption cycles. The maximum DDE adsorption capacity of poly(HEMA-MAsp) cryogels was found to be 31.51 mg DDE/g polymer for 50 mg DDE/L solution.

Molecular Imprinting Applications in Forensic Science

Producing molecular imprinting-based materials has received increasing attention due to recognition selectivity, stability, cast effectiveness, and ease of production in various forms for a wide range of applications. The molecular imprinting technique has a variety of applications in the areas of the food industry, environmental monitoring, and medicine for diverse purposes like sample pretreatment, sensing, and separation/purification. A versatile usage, stability and recognition capabilities also make them perfect candidates for use in forensic sciences. Forensic science is a demanding area and there is a growing interest in molecularly imprinted polymers (MIPs) in this field. In this review, recent molecular imprinting applications in the related areas of forensic sciences are discussed while considering the literature of last two decades. Not only direct forensic applications but also studies of possible forensic value were taken into account like illicit drugs, banned sport drugs, effective toxins and chemical warfare agents in a review of over 100 articles. The literature was classified according to targets, material shapes, production strategies, detection method, and instrumentation. We aimed to summarize the current applications of MIPs in forensic science and put forth a projection of their potential uses as promising alternatives for benchmark competitors.