High Protein Adsorption Capacity Research Articles

Adsorption of Bovine Serum Albumin on Carbon-Based Materials

The protein adsorption plays a very important role in biotechnology, biomolecular engineering and it is one of the main factors determining bio- and hemocompatibility of biomedical materials in medical applications, such as blood purification and wound healing. Here we report adsorption properties of two carbon-based materials, thermally expanded graphite (EGr) and graphene nanoplatelets (GnP), for bovine serum albumin (BSA), the most abundant blood plasma protein. The influence of the surface chemistry of expanded graphite on the mechanism of BSA adsorption was studied by using EGr modified with oxygen or nitrogen functionalities. Having low microporosity and the specific surface area in the range of 5 to 50 m2/g, the expanded graphite exhibits high protein adsorption capacity at high equilibrium concentrations, which makes this material a potential candidate for biomedical applications as a carrier for high molecular weight (HMW) drug delivery or adsorption of HMW metabolites. At low equilibrium concentrations, the effect of specific protein-surface functional groups interaction reveals the differences between the adsorption affinity of different surface modified EGr materials to BSA. The adsorption of BSA on GnP with a specific surface area of 286 m2/g and a developed micro-/mesoporous structure did not follow the same mechanism as seen with EGr materials. At low equilibrium concentration of BSA, GnP exhibits high adsorption efficiency. An important finding is that no release of nanoparticles from expanded graphite adsorbents was observed, which makes them potentially suitable for direct contact with blood and other tissues while very small nanoparticles were noticed in the case of graphene nanoplatelets.

Biologically inspired, catechol-coordinated, hierarchical organization of raspberry-like calcium phosphate nanospheres with high specific surface area.

The elaborate design of calcium phosphates (CaP) with a hierarchical structure for biomedical applications is severely restricted due to their instinctive pertinacious irregular agglomeration. Thus, the development of mesoporous CaP with large internal pores is far from satisfactory. In this study, catechol is selected as a modifier to intervene in the precipitation of CaP. Compared to pure CaP with smooth irregular aggregates with an average size of 110 nm, the catechol-intervened CaP (CaP/Cat) samples are raspberry-like nano-spherical assemblies of ca. 25 nm nanoparticles. The obtained spheres possess a mesoporous structure, large interior pores and high specific surface area, which endow them with a high protein adsorption capacity and high DNA delivery efficacy. Catechol is subjected to oxidative polymerization while CaP precipitation occurs. This simultaneous reaction is supposed to play a crucial role in directing the assembling of the CaP/Cat nanospheres. The flexible catechol moiety is shown to be a novel and promising modifier for manufacturing CaP with tunable structures and properties for various applications.

Silica Interlayer Formation of Mesoporous Silica Coatings on Hydroxyapatite Granules

Mesoporous silica (MPS) coatings on hydroxyapatite (HAp) granules and their protein adsorptive capabilities were studied. MPS particles were coated on HAp granules using a dip-coating method, but the HAp granules were not totally covered by the MPS particles. A silica interlayer was formed on the HAp granules via magnetron sputtering or the sol-gel method prior to the coating of the MPS. The HAp granules coated with the silica interlayer were fully covered by the MPS particles. An silica interlayer may offer bonding between the HAp granules and MPS coating. The adsorption of protein on the MPS-coated HAp granules was evaluated by UV-VIS spectroscopy. The adsorption capacity of protein on the HAp granules was improved by the MPS coatings on the HAp granules, and that of the HAp granules coated with the silica interlayer showed a higher protein adsorption capacity.

Grafting glycidyl methacrylate to Sepharose gel for fabricating high-capacity protein anion exchangers

To develop ion exchangers of high protein adsorption capacity, we have herein introduced atom transfer radical polymerization (ATRP) method to graft glycidyl methacrylate (GMA) onto Sepharose FF gel. GMA-grafted Sepharose FF resins of four grafting densities and different grafting chain lengths were obtained by adjusting reaction conditions. The epoxy groups on the grafted chains were functionalized by modification with diethylamine (DEA), leading to the fabrication of Sepharose-based anion exchangers of 14 different grafting densities and/or grafting chain lengths. The resins were first characterized for the effects of grafting density, chain length and ionic strength on pore sizes by inverse size exclusion chromatography. Then, the resins were evaluated by adsorption equilibria of bovine serum albumin (BSA) as a function of ionic capacity (IC) (chain length) at individual grafting densities. It was observed that at each grafting density there was a specific IC value (chain length) that offered the maximum equilibrium capacity. Of the resins with maximum values at individual grafting densities, the resin of the second grafting density with an IC value of 330mmol/L (denoted as FF-Br2-pG-D330) showed the highest capacity, 264mg/mL, about two times higher than that of the traditional ungrafted resin Q Sepharose FF (137mg/mL). This resin also showed the most favorable uptake kinetics among the resins of similar IC values but different grafting densities, or of the same grafting density but different IC values. Effects of ionic strength showed that the capacities of FF-Br2-pG-D330 were much higher than Q Sepharose FF at a wide range of NaCl concentrations (0–200mmol/L), and the uptake rates of the two resins were similar in the ionic strength range. Therefore, the dynamic binding capacity values of BSA on FF-Br2-pG-D330 were much higher than Q Sepharose FF as demonstrated at different residence times and ionic strengths. Taken together, the research has proved the success in the fabrication of high-capacity protein anion exchangers by grafting GMA onto Sepharose gel.

Magnesium whitlockite hollow microspheres: a comparison of microwave-hydrothermal and conventional hydrothermal syntheses using fructose 1,6-bisphosphate, and application in protein adsorption

Magnesium whitlockite hollow microspheres with high biocompatibility and protein adsorption capacity are synthesized by a rapid microwave-hydrothermal method using fructose 1,6-bisphosphate.

Microwave-Assisted Hydrothermal Rapid Synthesis of Calcium Phosphates: Structural Control and Application in Protein Adsorption.

Synthetic calcium phosphate (CaP)-based materials have attracted much attention in the biomedical field. In this study, we have investigated the effect of pH values on CaP nanostructures prepared using a microwave-assisted hydrothermal method. The hierarchical nanosheet-assembled hydroxyapatite (HAP) nanostructure was prepared under weak acidic conditions (pH 5), while the HAP nanorod was prepared under neutral (pH 7) and weak alkali (pH 9) condition. However, when the pH value increases to 11, a mixed product of HAP nanorod and tri-calcium phosphate nanoparticle was obtained. The results indicated that the pH value of the initial reaction solution played an important role in the phase and structure of the CaP. Furthermore, the protein adsorption and release performance of the as-prepared CaP nanostructures were investigated by using hemoglobin (Hb) as a model protein. The sample that was prepared at pH = 11 and consisted of mixed morphologies of nanorods and nanoprisms showed a higher Hb protein adsorption capacity than the sample prepared at pH 5, which could be explained by its smaller size and dispersed structure. The results revealed the relatively high protein adsorption capacity of the as-prepared CaP nanostructures, which show promise for applications in various biomedical fields such as drug delivery and protein adsorption.

Microwave-assisted rapid synthesis of magnesium phosphate hydrate nanosheets and their application in drug delivery and protein adsorption.

Magnesium phosphate biomaterial, as an alternative to well-known calcium phosphate biomaterials, is an excellent candidate for biomedical applications, owing to its outstanding biocompatibility and biodegradability. Herein, we report a simple strategy for the rapid synthesis of magnesium phosphate hydrate nanosheets (MPHSs) using the microwave-assisted hydrothermal method. This method is facile, rapid, surfactant-free and environmentally friendly. The product shows an excellent ability to promote osteoblast MC-3T3 adhesion and spreading, which indicates high biocompatibility. Moreover, the as-prepared MPHSs are explored for potential applications in the loading and release of the anticancer drug and protein adsorption, using docetaxel as a model anticancer drug and hemoglobin (Hb) as a model protein. The experiments indicate that the as-prepared MPHSs have a relatively high protein adsorption capacity and a high ability to damage tumor cells after loading docetaxel. Thus, the as-prepared MPHSs are promising for applications in various biomedical fields such as drug delivery and protein adsorption.

Synthesis, characterization and applications of calcium carbonate/fructose 1,6-bisphosphate composite nanospheres and carbonated hydroxyapatite porous nanospheres.

In this work, we first investigated the effect of fructose 1,6-bisphosphate, which is fructose sugar phosphorylated on carbons 1 and 6, on the biomineralization of calcium carbonate, and prepared calcium carbonate/fructose 1,6-bisphosphate (CC/FBP) composite nanospheres. Then, we investigated the transformation of CC/FBP composite nanospheres under microwave-assisted hydrothermal conditions and prepared carbonated hydroxyapatite (CHA) porous nanospheres. We found that FBP has a unique effect on the morphology and crystallization of calcium carbonate. FBP can control the morphology of calcium carbonate and provide the phosphorus source for the formation of CHA. The morphology and size of CC/FBP composite nanospheres can be preserved after transformation to CHA porous nanospheres under microwave-assisted hydrothermal conditions. The CC/FBP composite nanospheres and CHA porous nanospheres are efficient for anticancer drug (docetaxel) loading and release, and the drug delivery system shows a high ability to damage tumor cells, and thus is promising for application in drug delivery. The as-prepared CC/FBP composite nanospheres and CHA porous nanospheres have excellent biocompatibility and high protein adsorption capacity, as well as high efficiency for gene transfection.

Microwave Hydrothermal Transformation of Amorphous Calcium Carbonate Nanospheres and Application in Protein Adsorption

Calcium carbonate and calcium phosphate are the main components of biominerals. Among all of the forms of biominerals, amorphous calcium carbonate (ACC) and amorphous calcium phosphate (ACP) are the most important forms because they play a pivotal role in the process of biomineralization and are the precursors to the crystalline polymorphs. In this work, we first synthesized ACC in vitro using adenosine 5'-triphosphate disodium salt (ATP) as the stabilizer and investigated the transformation of the ACC under microwave hydrothermal conditions, and ACC/ACP composite nanospheres and carbonated hydroxyapatite (CHA) nanospheres were successfully prepared. In this novel strategy, ATP has two main functions: it serves as the stabilizer for ACC and the phosphorus source for ACP and CHA. Most importantly, the morphology and the size of the ACC precursor can be well-preserved after microwave heating, so it provides a new method for the preparation of calcium phosphate nanostructured materials using phosphorus-containing biomolecule-stabilized ACC as the precursor. Furthermore, the as-prepared ACC/ACP composite nanospheres have excellent biocompatibility and high protein adsorption capacity, indicating that they are promising for applications in biomedical fields such as drug delivery and protein adsorption.

Large Pore Mesoporous Silica Nanoparticles by Templating with a Nonsurfactant Molecule, Tannic Acid

We describe a one-pot synthesis of novel large-pore mesoporous silica nanoparticles using a nonsurfactant template, tannic acid, and protein immobilization on these particles. The tannic-acid-templated mesoporous silica nanoparticles (TA-MSNPs) possess tunable large pores (6–13 nm), unique pore morphology, and a uniform diameter of ca. 200 nm. TA-MSNPs show high protein adsorption capacity of 77.1 mg/g for lysozyme, 396.5 mg/g for bovine hemoglobin, and 130.0 mg/g for bovine serum albumin and rapid protein uptake. They can also adsorb a large amount of m-MDH (421 ± 13 mg/g) and protect this enzyme from the environment, as demonstrated by its high activity when encapsulated inside the mesopores of TA-MSNPs.

ATP‐Stabilized Amorphous Calcium Carbonate Nanospheres and Their Application in Protein Adsorption

Calcium carbonate is a common substance found in rocks worldwide, and is the main biomineral formed in shells of marine organisms and snails, pearls and eggshells. Amorphous calcium carbonate (ACC) is the least stable polymorph of calcium carbonate, which is so unstable under normal conditions that it is difficult to be prepared in vitro because it rapidly crystallizes to form one of the more stable polymorphs in aqueous solution. Herein, we report the successful synthesis of highly stable ACC nanospheres in vitro using adenosine 5'-triphosphate disodium salt (ATP) as a stabilizer. The effect of ATP on the stability of ACC nanospheres is investigated. Our experiments show that ATP plays an unique role in the stabilization of ACC nanospheres in aqueous solution. Moreover, the as-prepared ACC nanospheres are highly stable in phosphate buffered saline for a relatively long period of time (12 days) even under relatively high concentrations of calcium and phosphate ions. The cytotoxicity tests show that the as-prepared highly stable ACC nanospheres have excellent biocompatibility. The highly stable ACC nanospheres have high protein adsorption capacity, implying that they are promising for applications in biomedical fields such as drug delivery and protein adsorption.

Multifunctional hydroxyapatite nanoparticle-based affinity adsorbent with sensing and fluorescence imaging capacity.

Nickel hydroxide/hydroxyapatite (Ni(OH)2/HAP) nanoparticles (NPs) coated with rhodamine B hydrazide (RBH) were successfully synthesized in three steps. First, Ni(OH)2/HAP-COOH NPs were synthesized by a facile hydrothermal route in the presence of citric acid. Second, rhodamine B was reacted with hydrazine hydrate to obtain rhodamine B hydrazide (RBH). Finally, RBH was conjugated on the surface of Ni(OH)2/HAP-COOH NPs to form Ni(OH)2/HAP-RBH. As affinity adsorbents, these NPs can directly purify histidine-tagged (His-tagged) proteins from a mixture of lysed cells, and exhibit high protein adsorption capacity with a maximum value of 115 mg g-1. A prominent fluorescence enhancement at 578 nm was observed in the presence of Pt2+, accompanied by a change in absorption spectrum. These NPs display excellent selectivity and sensitive recognition of Pt2+ in comparison with other metal ions and anions with a detection limit of 0.03 μM. These NPs exhibit low cytotoxicity and can be used as a probe for Pt2+ and living cell imaging.

Synthesis of petal-like ferric oxide/cysteine architectures and their application in affinity separation of proteins

Petal-like ferric oxide/cysteine (FeOOH/Cys) architectures were prepared through a solvothermal route, which possessed high thiol group density. These thiol groups as binding sites can chelate Ni2+ ions, which can be further used to enrich and separate his-tagged proteins directly from the mixture of lysed cells without sample pretreatment. These results show that the FeOOH/Cys architectures with immobilized Ni2+ ions present negligible nonspecific protein adsorption and high protein adsorption capacity, with the saturation capacity being 88mg/g, which are especially suitable for purification of his-tagged proteins.

Titanate nanowire scaffolds decorated with anatase nanocrystals show good protein adsorption and low cell adhesion capacity

Background and methods:In this report, layered microporous titanate nanowire scaffolds (TiNWs) were constructed via a hydrothermal route and then decorated with anatase nanocrystals (ANs@TiNWs) by immersion in TiCl4 solution. The diameter and specific surface area of the ANs@TiNWs was measured. The TiNWs and ANs@TiNWs were then compared for their ability to adsorb protein and adhere to MG63 cells.Results:The diameter and specific surface area of the ANs@TiNWs were significantly larger than for TiNWs, and the ANs@TiNWs had an enhanced protein-adsorbing effect. It was found that the MG63 cells were less able to adhere to the flat titanium substrate than the TiNWs and ANs@TiNWs, and that this cell-repellant ability was greater with ANs@TiNWs. Other MG63 cell functions, proliferation in particular, were also inhibited by ANs@TiNWs.Conclusion:ANs@TiNWs show a high protein adsorption and cell-repellant capacity which would be useful in drug delivery.

針葉樹および広葉樹リグノクレゾール固定化セルラーゼの特性比較

Saccharification of cellulosic biomass is essential for the production of bioethanol and other industrial chemicals. The development of an immobilized cellulase is one important alternative to save the cost of cellulase. Until now, various inorganic and organic materials have been tested for the carrier of immobilized cellulases. A lignin-based polymer: lignophenol is also a candidate due to the high protein adsorption capacity via hydrophobic interaction. In this study, two kinds of lignocresols were synthesized from a softwood (Hinoki) and a hardwood (Eucalyptus) with p-cresol and 72% sulfuric acid through the phase separation system. The immobilized cellulases were prepared by simple mixing of Trichoderma cellulase and the lignocresols. The adsorption capacity of Eucalyptus lignocresol for cellulase was lower than Hinoki. It is probably because Eucalyptus lignocresol is rather hydrophilic due to the lower molecular weight and the linear structure with more phenolic hydroxyl groups. The dependences of temperature on the enzymatic activities of the Hinoki and Eucalyptus lignocresol-immobilized cellulases were similar to the native cellulase. While, Hinoki and Eucalyptus lignocresols demonstrated the wider distinct optimum pH range than native cellulase, respectively. Lignocresol-immobilized cellulase successfully hydrolyzed CMC-Na with a small gradual decrease of the enzymatic activity as it was reused repeatedly. The reduction of the enzymatic activity was more pronounced in Eucalyptus than in Hinoki.

Printable and flexible macroporous organosilica film with high protein adsorption capacity

An approach for creating a flexible and macroporous silsesquioxane film using phase separation method is described. The porous film was prepared by a simple coating method where sol–gel solution containing polyacrylic acid (PAA) and 1,6-bis(trimethoxysilyl)hexane in water was applied on boehmite silica coated polymethylmethacrylate (PMMA) film. After drying, the water soluble PAA template was removed by washing the film with water revealing the porous film. With certain ratios of PAA and water, fully co-continuous pore system with open surface was obtained. Porous films with 3–4 μm thickness were found to be highly flexible. The biocompatibility of the porous film was tested by immobilizing a high affinity biotin-binding chimeric avidin (ChiAVD(I117Y)) into the porous matrix The porous film was found to adsorb higher amounts of functional chimeric avidin compared to the pure PMMA film or a boehmite silica coated PMMA film.

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 Cu2+-attached sporopollenin particles (Cu2+-ASP) having large surface area for high protein adsorption capacity. Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA)-based monolithic cryogel column embedded with Cu2+-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, Cu2+ ions were attached to sporopollenin particles (SP), then the supermacroporous PHEMA cryogel with embedded Cu2+-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 (10mg) 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 0.5mL/min, and at 5°C. The maximum amount of HSA adsorption from aqueous solution was very high (677.4mg/g SP) with initial concentration 6mg/mL. It was observed that HSA could be repeatedly adsorbed and desorbed to the embedded Cu2+-ASP in PHEMA cryogel without significant loss of adsorption capacity.

Preparation of Monodispersed Uniform Silica Spheres with Large Pore Size for Fast Adsorption of Proteins

In this paper, a “temperature-induced gelation” method, combined with microfluidic flows, has been developed to synthesize the uniform silica spheres with large pore structures for the fast adsorption of bovine serum albumin (BSA). The reversible-thermosentive property of methylcellulose (MC) and auxiliary function of poly(ethylene glycol) (PEG) were introduced to realize a fast gelation in a coaxial microfludic device. The effects of temperature and MC concentration on the gelation process were investigated by monitoring the change of viscosity of sol system over time. The silica spheres with different morphologies of internal structure were synthesized by adjusting the concentration of MC. The prepared silica spheres had large pore volumes (>2.0 mL/g) and an average mesopore diameter of >12 nm. Meanwhile, a large amount of macropores existed in the silica spheres. The bimodal mesopore-marcopore structure resulted in a high protein adsorption capacity (590 mg/g) and a fast adsorption rate (reaching equilibrium within 9 h).

Fast adsorption and separation of bovine serum albumin and lysozyme using micrometer‐sized macromesoporous silica spheres

Micrometer-sized silica spheres with bimodal macromesoporous structures are synthesized continuously by a modified gelation technology, and a novel coaxial microfluidic device is applied to control the size of the silica spheres. These spheres are used as a new protein adsorbent to realize fast adsorption and separation of protein mixture. BSA and lysozyme (LYS) are as model proteins with different sizes and pIs. High protein adsorption capacity and rapid adsorption rate have been achieved. Fast separation of a binary mixture of BSA and LYS through a short packed column (50 mm x 4.6 mm id) has also been successfully realized. LYS was selectively adsorbed while BSA flowed through the column in 12 s at a flow rate of up to 5.0 mL/min. As a result, an ultrafast adsorption and separation of BSA and LYS was obtained, showing great potential for applications in fast, large-scale protein separation processes of these monodispersed silica spheres.

Bioactive composite ceramics in the hydroxyapatite-tricalcium phosphate system

Synthetic materials based on hydroxyapatite (HA), an analogue of the mineral component of the bone tissue, are used in medicine for the repair of damaged bone tissue [1‐3]. A new repair technology is based on implanting porous ceramic scaffolds containing cultivated cells and proteins into the bone tissue [4]. The formation of new bone tissue is a complex process that includes protein adsorption as an important stage [5, 6]. Scaffolds should be resorbable with time in the human body with gradual replacement by newly formed bone tissue and should ensure a high protein-adsorption capacity. Hydroxyapatite is stable against dissolution by body fluids, whereas tricalcium phosphate (TCP) has a much higher resorption rate compared to that of HA. By varying the component ratio in an HA/TCP composite, one can control the resorption rate. The problems of design of such composite materials have been considered in reviews [7, 8]. Two-phase composites (TCMs) are produced by thermal decomposition of calcium-deficient HA followed by sintering [8]. Using this method, it is difficult to control the component ratio in the material. Some aspects of the influence of the phase composition on the biological behavior of TCMs remain obscure. This study is devoted to the production of TCMs with specified composition and porosity and elucidation of the question of which factor, porosity or phase composition, is more important for protein adsorption.