The hydroxyalkyl amination of agarose gels was studied as an approach to improve adsorption of polyphenols and pharmaceuticals from water. Three commercially available agarose gels, Zetarose FlashFlow4, ZetaCell-CL6B and Sepharose 4B were chemically modified using tris-(hydroxymethyl)aminomethane, TRIS, and ethanolamine, EA. The adsorbed amounts of bisphenol A and diclofenac were significantly higher on TRIS- and EA-derivatives compared with the parent gels. Regarding bisphenol A adsorption on TRIS-ZetaCell-CL6B, a maximal adsorption capacity, Q max of 16 μmol/mL gel and an equilibrium dissociation constant KL of 2.7 × 10−4 mol/L were observed. Filtration of diclofenac-contaminated water through TRIS-Zetarose FlashFlow 4 resulted in a 10-fold reduction of the pollutant concentration within 64 column volumes of the effluent. The moderate binding affinity of polyphenols to TRIS- and EA-adsorbents facilitates efficient polyphenol desorption and column regeneration. The effects of TRIS- and EA-substituents in agarose gels, can be harnessed for the development of environmental adsorbents, as well as for the preparative separation of polyphenols and pharmaceuticals. We consider the physical shapes and textures of the prospective adsorbents with a particular focus on spongy macroporous cryogels. These innovative materials hold promise for future applications in liquid and air filtration.

N-vinylimidazole-divinylbenzene (VI-DVB) copolymer beads with a N-vinylimidazole (VI) weight content ranging from 7% to 15% were studied as possible adsorbents for hemoperfusion and compared with the cross-linked polystyrene beads from commercial devices. All the beads had a large volume fraction of mesopores with diameters of 2–50 nm, quantified by nitrogen adsorption, and BET areas from 500 to 1000 m²/g. Metal-chelate adsorption of copper (II) ions on VI-DVB was high in 0.15 M NaCl (up to 40 μmol/mL), and low in blood plasma (< 1 μmol/mL). Reversible adsorption of blood plasma proteins was high (> 100 mg/mL beads) on all the bead types. Irreversibly adsorbed proteins eluted by 2% SDS included albumin, fibrinogen, fibronectin, and transferrin. Metal chelating contributed to the irreversible adsorption. Unlike the beads from commercial devices, VI-DVB beads adsorbed the LPS endotoxin from plasma. Adsorption of bilirubin and IL-6 was high on all the beads tested, but VI-DVB beads were better adsorbents of bile acids. VI-DVB are promising as components of multifunctional devices for blood purification applicable to treatment of diseases where conventional devices have lower or negligible adsorption capacity.

Three types of polymer-coated glass slides were prepared by acylation of their y-aminopropyl derivatives with succinic anhydride or poly(p-nitrophenyl acylate) (PNPA) at various reaction times. The variations in duration of chemical adsorption of PNPA allowed control over nano-corrugation of the reactive surfaces employed for biosensing. The visually smooth and optically clear polymer-coated slides were used for immobilization of a conjugate of bovine serum albumin with chloramphenicol (CAP) and label-free measurement of concentration of this antibiotic. The sensor chips prepared in this way provided strong biosensing response due to fast biomolecular interactions and efficient competition of the target analyte during indirect immunoassay. The kinetics of formation and dissociation of immune complexes "conjugate-antibody" on the sensor chip surface was registered by the label-free methods of spectral-correlation and spectral-phase interferometry. The average thickness of immune complex adsorption layers was in the range of 5-12 nm. The highest value of kinetic association con- stant (k(on) = 5 x 10(4) M-1S-1) and the lowest equilibrium dissociation constant (K-diss = 2 x 10(-8) M-1) were achieved with the chips originated in the PNPA-coated slides, which were produced under short (2 min) polymer chemisorption and exhibited nano-corrugation almost unchanged with respect to the parent glass, according to the atomic-force microscopy. The detection limit for CAP detection was 80 pg/mL, and the dynamic range was 5 orders. The proposed methods for fabrication of sensor chips with nano-corrugated surface, the results of their characterization, as well as the developed assay can be employed for high-throughput recording of multiple molecular interactions by spectral interferometry and in a wide range of biosensing platforms for registration of biologically active compounds in medicine, veterinary, food control and ecological monitoring.

Thin macroporous poly(vinyl alcohol) (PVA) hydrogels were produced by cross-linking of PVA in a semi-frozen state with glutaraldehyde (GA) on glass slides or in the wells of microtiter plates. The 100-130 μm-thick gels were mechanically transferable, squamous translucent films with a high porosity of 7.2 ± 0.3 mL/g dry PVA i.e. similar to larger cylindrical PVA monoliths of the same composition. Additional treatment of the gels with 1% GA increased the aldehyde group content from 0.7 to 2.4 μmol/mL as estimated using dinitrophenylhydrazine (DNPH) reagent. Translucency of the gels allowed registration of UV-visible spectra of the DNPH-stained films. The catalytic activity of trypsin covalently immobilized on thin gels in the microtiter plates was estimated with chromogenic substrate directly in the wells, and indicated that the amount of protein immobilized was at least 0.34 mg/mL gel. Human immunoglobulin G (IgG) immobilized on thin gels at 0.1-10 mg/mL starting concentrations could be detected in a concentration-dependent manner due to recognition by anti-human rabbit IgG conjugated with peroxidase and photometric registration of the enzymatic activity. The results indicate good permeability of the hydrogel pores for macromolecular biospecific reagents and suggest applications of thin reactive PVA hydrogels in photometric analytical techniques.

Smart, or responsive polymers can reversibly change their state of aggregation, thus switching from water-soluble to insoluble state, in response to minor changes in temperature, pH or solvent composition. Grafting of these polymers to solid surfaces imparts the surfaces with controllable wettability and adsorption behaviour. The review summarizes the theoretical models and the results of physical measurements of the conformational transitions in grafted polymer chains and polymer brushes. Primary attention is paid to the grafting density and the length and spatial arrangement of grafted chains, the role of polystyrene, organosilane or alkanethiol sublayers and their effects on adsorption of proteins and adhesion of cells. The key applications of grafted smart polymers such as cell culture and tissue engineering, cell and protein separation, biosensing and targeted drug delivery are surveyed.

Monolithic composites of Polyphepan® or Kraft lignin embedded in a poly(vinyl alcohol) (PVA) matrix were synthesized using cryogelation technique and studied as flow permeable adsorbents for bisphenol A and erythromycin removal from water. Adsorption isotherms of bisphenol A on pristine Polyphepan provided the equilibrium dissociation constant KL=2.6×10−6M and the maximal binding capacity Qmax=20μmol/g; for erythromycin KL was in the 9.6×10−6M to 5.8×10−5M range, and Qmax was between 55μmol/g and 94μmol/g. Embedment of lignins into PVA cryogels resulted in monoliths with adequate flow permeability and the composites essentially retained the binding capacity for both bisphenol A and erythromycin. Percolation of contaminated water through the monoliths resulted in 10-fold reduction of the pollutant concentrations within 12–70 column volumes of the effluent. Due to the higher loading of lignin, the Kraft lignin–PVA composite showed higher adsorption capacity for erythromycin than Polyphepan–PVA. Stability and reversible compression of the monoliths in the flow of water were studied. Limitations are associated with leakage of soluble lignin, strongly expressed in the case of Kraft lignin-containing composites.

Effective technologies are required to remove organic micropollutants from large fluid volumes to overcome present and future challenges in water and effluent treatment. A novel hierarchical composite filter material for rapid and effective removal of polar organic contaminants from water was developed. The composite is fabricated from phenolic resin-derived carbon microbeads with controllable porous structure and specific surface area embedded in a monolithic, flow permeable, poly(vinyl alcohol) cryogel. The bead-embedded monolithic composite filter retains the bulk of the high adsorptive capacity of the carbon microbeads while improving pore diffusion rates of organic pollutants. Water spiked with organic contaminants, both at environmentally relevant concentrations and at high levels of contamination, was used to determine the purification limits of the filter. Flow through tests using water spiked with the pesticides atrazine (32 mg/L) and malathion (16 mg/L) indicated maximum adsorptive capacities of 641 and 591 mg pollutant/g carbon, respectively. Over 400 bed volumes of water contaminated with 32 mg atrazine/L, and over 27,400 bed volumes of water contaminated with 2 μg atrazine/L, were treated before pesticide guideline values of 0.1 μg/L were exceeded. High adsorptive capacity was maintained when using water with high total organic carbon (TOC) levels and high salinity. The toxicity of water filtrates was tested in vitro with human epithelial cells with no evidence of cytotoxicity after initial washing.

Macroporous monolithic composites with embedded divinylbenzene-styrene (DVB-ST) polymeric particles were prepared by cryogelation techniques using poly(vinyl alcohol) or agarose solutions. Scanning electron microscopy images showed multiple interconnected pores with an average diameter in the range of 4 to 180 μm and quite homogeneous distribution of DVB-ST particles in the composites. Biocompatibility of the composites was assessed by estimation of the C5a fragment of complement in the blood serum and concentration of fibrinogen in the blood plasma which contacted the composites. A time-dependent generation of C5a fragment indicated weak activation of the complement system. At the same time, the difference in fibrinogen concentration, one of the most important proteins in the coagulation system of the blood, between the pristine blood plasma and the plasma, circulated through the monolithic columns, was insignificant.

Composite monolithic adsorbents were prepared by the incorporation of neutral polystyrene divinylbenzene (PS-DVB) microparticles into macroporous polymer structures produced by cryogelation of agarose or poly(vinyl alcohol). The composite materials exhibited excellent flow-through properties. Scanning electron microscopy of the composite cryogels revealed that the microparticles were covered by thin films of poly(vinyl alcohol) or agarose and thus were withheld in the monolith structure. Plain PS-DVB microparticles showed efficient adsorption of albumin-bound toxins related to liver failure (bilirubin and cholic acid) and of cytokines (tumor necrosis factor-alpha and interleukin-6). The rates of adsorption and the amount of adsorbed factors were lower for the embedded microparticles as compared to the parent PS-DVB microparticles, indicating the importance of the accessibility of the adsorbent pores. Still, the macroporous composite materials showed efficient adsorption of albumin-bound toxins related to liver failure as well as efficient binding of cytokines, combined with good blood compatibility. Thus, the incorporation of microparticles into macroporous polymer structures may provide an option for the development of adsorption modules for extracorporeal blood purification.

Adsorption of myoglobin (Mb), bovine serum albumin (BSA) and γ-globulin (GG) onto activated carbons (ACs) with different pore size distributions, and poly(vinyl alcohol) (PVA) monolithic cryogels containing AC particles was studied. The highest initial rate of Mb adsorption was observed for AC having the largest specific surface area (1939 m(2) g(-1)) and pore volume (1.82 cm(3) g(-1)). The adsorption kinetics of proteins was characterized by a bimodal shape of the distribution f(D) function of an effective diffusion coefficient. Adsorption isotherms of Mb and GG were of Freundlich type within the studied range of equilibrium concentrations (10-150 μg mL(-1)). The distributions of free energy of protein adsorption were bimodal and reflected both interactions with carbon surfaces and self-association of proteins. Adsorbed amounts of Mb were the highest among the proteins studied (up to 700 mg g(-1) carbon), which was attributed to the higher fraction of pores accessible for Mb. Incorporation of carbon particles into PVA-based cryogel resulted in macroporous monolithic composite materials (AC-PVA) exhibiting good flow-through properties. Scanning electron microscopy of the composites showed macroporous aggregates of carbon particles held together by films and bridges of PVA. The rates of adsorption and adsorbed amounts of proteins on AC-PVA were reduced compared to the pristine carbon and depended on the carbon content in the composites. Nevertheless, adsorption of Mb on AC-PVA took place even in the presence of 500-fold higher concentration of BSA. This indicated a possibility of Mb clearance from blood plasma using the PVA-carbon monoliths.

A set of glutaraldehyde (GA) cross-linked poly(vinyl alcohol)/activated carbon (PVA/GA/AC) composites prepared in the form of monolithic rods using a cryogelation technique and studied using adsorption, mercury porosimetry, scanning electron microscopy (SEM), and quantum chemistry methods display porosity similar to that of PVA/GA cryogel at a high GA content (content ratio GA/AC = 1 and GA/PVA = 0.2). GA cross-linked PVA multilayer coverage is an effective barrier for adsorption on AC particles. Variations in surface chemistry (AC initial and oxidized in air at 300 C for 12 h) and content (14-62.5%w/w) of ACs in PVA/GA/AC composites relatively weakly affect their textural characteristics at a high GA content (specific surface area S-BET < 120 m(2)/g, pore volume V-p < 0.35 cm(3)/g). However, PVA/GA/AC composite rods formed with a lower concentration of GA (content ratio GA/AC = 1/6 and GA/PVA = 1/10) have significantly greater S-BET (similar to 500 m(2)/g) and V-p (>0.55 cm(3)/g) values because of improved accessibility of the AC surface. This provides better adsorption of methylene blue as a probe compound.

The binding of mucin to water-soluble copolymers of N,N-dimethylacrylamide and N-acryloyl-m-aminophenylboronic acid grafted on the surface of glass is studied. Atomic force microscopy studies show that many graft copolymer islands 20–200 nm in diameter and 50 nm in height occur on the modified surface of flat glass. Owing to the presence of phenyl boronate groups, the copolymer behaves as a weak polyelectrolyte (pK a = 9.0) and, in the grafted state in an aqueous solution, experiences reversible transitions between states with higher and lower degrees of ionization. As evidenced by spectral correlation interferometry, this phenomenon brings about a change in the thickness of the grafted layer by approximately 0.5 nm. The ability of phenyl boronate groups to form cyclic esters with diol and polyol groups results in complexation of the soluble copolymer with mucin oligosaccharides and entails the appearance of slowly growing submicron particles formed by similarly charged polymers. The specificity of complexation is confirmed by dissolution of particles in the presence of fructose: a saccharide with a strong affinity for phenyl boronate groups. The binding of mucin to glass, which is chemically modified with the above copolymer, leads to formation of an adsorption layer with a thickness of 1.2–1.8 nm. Thus, boronate-containing copolymers are suitable for preparing carriers with controllable adsorption properties with respect to polyols, including mucinlike proteins of cellular glycocalyxes.

Reversible changes of the height of a polymer brush containing phenylboronic acid were studied. The polymer brush thickness underwent reversible changes of 0.5-1 nm, in response to the changes in composition of the contacting aqueous phase from deionized water to bicarbonate buffer and vice versa, apparently due to the conformational transition of the weak polyelectrolyte to the more extended electrically charged state. Adsorption of mucin glycoprotein to the polymer brush took place due to boronate/sugar interactions between the glycoprotein and the graft copolymer and resulted in further increase of the brush height by ca. 1.5 nm, as observed by means of spectral correlation spectroscopy and ellipsometry.

Boronate-containing thin polyacrylamide gels (B-Gel), polymer brushes (B-Brush) and chemisorbed organosilane layers (B-COSL) were prepared on the surface of glass slides and studied as substrates for carbohydrate-mediated cell adhesion. B-COSL- and B-Brush-modified glass samples exhibited multiple submicron structures densely and irregularly distributed on the glass surface, as found by scanning electron microscopy and atomic force microscopy. B-Gel was ca. 0.1mm thick and contained pores with effective size of 1–2μm in the middle and of 5–20μm on the edges of the gel sample as found by confocal laser scanning microscopy. Evidence for the presence of phenylboronic acid in the samples was given by time-of-flight secondary ion mass-spectrometry (ToF SIMS), contact angle measurements performed in the presence of fructose, and staining with Alizarin Red S dye capable of formation specific, fluorescent complexes with boronic acids. A comparative study of adhesion and cultivation of animal cells on the above substrates was carried out using murine hybridoma M2139 cell line as a model. M2139 cells adhered to the substrates in the culture medium without glucose or sodium pyruvate at pH 8.0, and then were cultivated in the same medium at pH 7.2 for 4 days. It was found that the substrates of B-Brush type were superior both regarding cell adhesion and viability of the adhered cells, among the substrates studied. MTT assay confirmed proliferation of M2139 cells on B-Brush substrates. Some cell adhesion was also registered in the macropores of B-Gel substrate. The effects of surface microstructure of the boronate-containing polymers on cell adhesion are discussed. Transparent glass substrates grafted with boronate-containing copolymers offer good prospects for cell adhesion studies and development of cell-based assays.

Radical copolymerization of acrylamide (Am) (90 mol%) with N-acryloyl-m-aminophenylboronic acid (NAAPBA) (10 mol%) carried out on the surface of glass slides in aqueous solution and in the absence of chemical cross-linkers, resulted in the formation of thin semitransparent gels. The phenylboronic acid (PBA) ligand density was ca. 160 micromol/ml gel. The gels exhibited a macroporous structure and displayed optical response to sucrose, lactose, glucose and fructose in 50 mM sodium phosphate buffer, in the pH range from 6.5 to 7.5. The response was fairly reversible and linearly depended on glucose concentration in the wide concentration range from 1 to 60 mM at pH 7.3. The character of response was explained by the balance of two competing equilibrium processes: binding of glucose to phenylboronate anions and binary hydrophobic interactions of neutral PBA groups. The apparent diffusion coefficient of glucose in the gels was ca. 2.5 x 10(-7) cm(2)/s. A freshly prepared gel can be used daily for at least 1 month without changes in sensitivity. Autoclaving (121 degrees C, 1.2 bar, 10 min) allows for the gels sterilization, which is important for their use as glucose sensors in fermentation processes.

Thin semitransparent gels were prepared by radical copolymerization of N-acryloyl-m-aminophenylboronic acid (NAAPBA) and acrylamide (AAm) taken in molar ratios from 8:92 to 16:84, respectively, in water. The gels were characterized by the content of immobilized NAAPBA and monomer conversion. Scanning electron microscopy revealed the micrometer size pores in the dried gels. The wet gels displayed a linear optical response to sugars with sensitivity decreasing in the series: d-fructose, d-galactose, d-glucose, d-mannose, N-acetyl-d-glucosamine in the sugar concentration range from 1 to 40–60mM at pH 7.3. Cross-linking of the gels with N,N-methylene-bis-acrylamide decreased the strength of optical response. Specific binding capacity of a diol-containing dye Alizarin Red S in the gels at pH 7.0 coincided with the content of immobilized NAAPBA indicating the 1:1 stoichiometry of the reaction and, therefore, good accessibility of the boronic acid ligands for water-soluble diols. Permeability of the gels was studied with a non-interacting dye Ethyl Orange exhibiting the pore diffusion coefficient of 1.4×10−7cm2/s. The rate of optical response of the gels to glucose was found to be determined by diffusion of sugar into the relatively thick gels (l=0.35–1mm) with effective diffusion coefficients of 2×10−7cm2/s. In the thinner gels (l=0.1mm) the input of other kinetic processes, such as affinity binding or structural rearrangements of the gel, was noticeable.

Boronate-containing polymer brushes were synthesized by free radical copolymerization of N,N-dimethylacrylamide (DMAA) and N-acryloyl-m-phenylboronic acid (NAAPBA) (9:1) on the surface of 3-mercaptopropyl-silylated glass plates and capillaries. The brushes were characterized with time-of-flight secondary ion mass-spectrometry (ToF SIMS), atomic force microscopy and contact angle measurements. Fructose caused a well-expressed drop spreading on the surface of copolymer-grafted glass, due to the strong interaction with the boronate groups. Sedimentation of murine hybridoma cells M2139 or human myeloid leukemia cells KG1 onto the DMAA-NAAPBA copolymer-grafted glass plates from 10 mM phosphate buffer solution (pH 8.0) resulted in the cell adhesion. The adhered M2139 and KG1 cells could be quantitatively detached from the grafted plates with 0.1 M fructose, which competed with cell surface carbohydrates for binding to the boronates. Evaluation of the binding strength between M2139 cells and the copolymer brush was performed by exposure of the adhered cells to a shear stress. Detachment of a fraction of 18% of the adhered M2139 cells was obtained at a shear force of 1400-2800 pN/cell generated by the running phosphate buffer (pH 8.0), whereas the remaining adhered cells (70%) could be detached with 0.1 M fructose dissolved in the same buffer. Possible applications of the boronate-containing polymer brushes to affinity cell separation can be based upon the facile recovery of the attached cells.