牛血清蛋白在共聚物水凝胶接触镜材料上的沉积过程研究

将水凝胶膜样品置于牛血清蛋白(BSA)的水溶液中,沉积一定时间后,采用染料染色结合分光光度法分析沉积前后BSA浓度的变化,计算沉积量,并采用洗脱法测试BSA与水凝胶材料的结合程度.结果表明,BSA的沉积过程为不可逆过程;BSA的沉积作用不受共聚物水凝胶材料中NVP(N-乙烯基吡咯烷酮)结构单元吸附作用的控制;BSA与水凝胶材料松散结合,很容易洗脱;沉积在水凝胶膜表面上的BSA对后续沉积过程无影响.     

Nanoscopic Characterization of Stearic Acid Release from Bovine Serum Albumin Hydrogels

The release behavior of 16‐doxyl stearic acid (16‐DSA) from hydrogels made from bovine serum albumin (BSA) is characterized. 16‐DSA serves as a model tracer molecule for amphiphilic drugs. Various hydrogel preparation procedures are tested and the fatty acid release from the different gels is compared in detail. These comparisons reach from the macroscopic level, the viscoelastic behavior via rheological characterization to changes on the nanoscopic level concerning the secondary structure of the protein during gelation through infrared (ATR‐IR) spectroscopy. 16‐DSA‐BSA interaction via continuous wave electron paramagnetic resonance (CW EPR) spectroscopy in addition gives a nanoscopic view of small molecule–hydrogel interaction. The combined effects of fatty acid concentration, hydrogel incubation time, and gelation procedures on release behavior are studied via CW EPR spectroscopy and dynamic light scattering (DLS) measurements, which provide deep insight on the interaction of 16‐DSA with BSA hydrogels and the nature and size of the released components, respectively. It is found that the release rate of the fatty acid from BSA hydrogels depends on and can thus be tuned through its loading percentage, duration of hydrogel formation and the type of gelation methods. All of the results confirm the potential of these gels as delivery hosts in pharmaceutical applications allowing the sustained release of drug.     

N-乙烯吡咯烷酮/甲基丙烯酸-β-羟乙酯无规共聚物凝胶对蛋白质吸附机理的研究

用紫外分光光度法研究了牛血清白蛋白(BSA)在N-乙烯吡咯烷酮(NVP)/甲基丙烯酸-β-羟乙酯(HEMA)共聚物水凝胶上的吸附量.结果表明,BSA在凝胶上的吸附关系既可用Langmuir方程描述,又可用计量置换吸附Freundlich方程描述,且用Langmuir方程描述更为优越.研究了凝胶对BSA的吸附动力学行为,建立牛血清白蛋白的吸附动力学模型,发现用Bangharm方程对BSA吸附动力学曲线拟合程度较好,Bangharm方程可以较好地描述BSA在NVP/HEMA凝胶上的吸附动力学行为.     

Interaction between congo red and copper in a binary adsorption system: Spectroscopic and kinetic studies

This study focused on the competitive adsorption of congo red (CR) and copper by chitosan hydrogel beads in a binary adsorption system. Spectroscopic analysis, including Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were integrated with kinetic studies to elucidate the interaction. It was determined that chitosan hydrogel beads show better adsorption performance towards congo red and copper in single adsorption systems. The addition of copper caused a 25% reduction in congo red adsorption capacity, while copper adsorption was enhanced slightly by the presence of congo red. The adsorption results for binary adsorption systems seem due to competition for the present amine and hydroxyl groups that may occur between congo red and copper. A congo red–copper complex was formed in binary adsorption systems. Copper attached to chitosan hydrogel beads individually or was bound by the congo red–copper complex, which resulted in an increase in adsorption capacity. Chitosan exhibited higher adsorption selectivity to the free Cu²⁺ ion than the congo red–copper complex in the binary adsorption system. Adsorption of the congo red–copper complex indicated an inhibition in the attachment of the free Cu²⁺ ion in the form of Cu(II).     

Adsorption of bovine serum albumin to acrylamide–itaconic acid hydrogels

In this study, acrylamide–itaconic acid hydrogels containing different amounts of itaconic acid prepared by irradiating with γ radiation are discussed. They have been used in experiments of swelling, diffusion and bovine serum albumin (BSA) adsorption. Maximum and minimum swellings were observed with water (1520%) and BSA (890%), respectively. Diffusion of water, NaCl and BSA within hydrogels were found to be non-Fickian in character. In the experiments of BSA adsorption, type III adsorption was found. The hydrogel prepared with 60 mg itaconic acid and irradiated at 2.00 kGy was found to be the best adsorption system for BSA. The adsorption capacity of acrylamide–itaconic acid hydrogel was found to exceed that of acrylamide hydrogel by more than 80–100%.     

pH/temperature - sensitive imprinted ionic poly(N-tert-butylacrylamide-co-acrylamide/maleic acid) hydrogels for bovine serum albumin

In this study, we have prepared pH/temperature-sensitive imprinted ionic poly(N-tert-butylacrylamide-co-acrylamide/maleic acid) [P(TBA-co-AAm/MA)] hydrogels for bovine serum albumin (BSA) by using molecular imprinting method. BSA adsorption from aqueous BSA solutions was investigated with two types of hydrogel systems prepared by non-imprinted and imprinted methods. Hydrogels imprinted with BSA showed higher adsorption capacity and specificity for BSA than hydrogels prepared by the usual procedure. At all studied conditions, the highest BSA adsorption was observed in the hydrogel imprinted with 8.63 wt.-% BSA. In addition, the imprinted hydrogels exhibited both for good selectivity BSA and high adsorption rate depending on the number of BSA-sized cavities. Adsorption studies showed that other stimuli, such as pH, temperature and initial BSA concentration also influenced the BSA adsorption capacity of both non-imprinted and imprinted hydrogels.     

Efficiency of Superparamagnetic Nano Iron Oxide Loaded Poly(Acrylamide-co-Maleic acid) Hydrogel in Uptaking Cu2+ Ions from Water

A novel superparamagnetic iron oxide nanoparticles loaded poly(acrylamide-co-maleic acid) hydrogel (superparamagnetic PAM hydrogel) has been synthesized and cross-linked by methylene bisacrylamide for the investigation of its efficiency in uptaking copper ions from aqueous solution by batch method. The swelling behavior of the hydrogel was investigated. Metal ion uptake capacity of the adsorbent was evaluated in the light of varying pH, contact time, temperature, adsorbent dose, and different copper ion concentration. The synthesized superparamagnetic PAM was characterized by FTIR and XRD analysis. The structure and coating of the magnetic nanoparticles were characterized by XRD and FTIR analysis respectively. The adsorption data was fitted well in the Langmuir, Freundlich, and Temkin models and various static parameters were calculated. It is stated that this hydrogel could be regenerated efficiently (>97%) and used repeatedly.     

The effect of external stimuli on the Bovine Serum Albumin adsorption capacity of poly(acrylamide/maleic acid) hydrogels prepared by gamma rays

The effects of external stimuli such as pH of the buffer solution, ionic strength, temperature and the amount of poly-electrolyte monomer in the hydrogel system on the Bovine Serum Albumin (BSA) adsorption capacity of poly(acrylamide/maleic acid) [P(AAm/MA)] hydrogels were investigated. Poly-electrolyte P(AAm/MA) hydrogels with varying compositions were prepared by irradiating acrylamide/maleic acid/water mixtures with γ rays at ambient temperature. Langmuir type adsorption isotherms were observed for all prepared hydrogels. Increase of ionic strength of the buffer solution from 0.01 to 0.1 mol dm⁻³ decreased the adsorption capacity of hydrogels and zero adsorption was observed in the presence of 0.1 mol dm⁻³ Na⁺ and Ca²⁺ ion in the adsorption medium. The adsorption capacity of hydrogels was found to increase from 0 to 120 mg BSA/g dry gel, by changing external stimuli and hydrogel composition.     

The complex formation between polyacrylamide containing glycine end groups and bovine serium albumin in the presence of copper (II) in neutral aqueous media

Complex formation between end group containing polyacrylamide and BSA has been studied in neutral water. Water soluble and insoluble complexes are formed when divalent copper ions are added to the solution.The contacts between protein and polyelectrolyte are achieved via chelate unit formation in which the copper ion is attached at the center. The solubility of the polycomplexes depends on protein/polymer ratio. Starting with very low concentration of protein in the system, phase separation takes place. Above the critical ratio of the protein/polymer, the mixture again exhibits water soluble character. The velocity of the formation of insoluble ternary complexes has been investigated by spectrophotometric method at different reaction conditions (preparation of mixture, ratio of components, low molecular salts, temperature and stirring, molecular weight of polyelectrolyte and Cu²⁺ concentration). A hypothetical structural scheme for the formation of soluble and insoluble ternary polycomplexes is proposed.     

The Rebinding Properties of Bovine Serum Albumin Imprinted Calcium Alginate/Phosphate Hybrid Microspheres Via the Adjustment of pH Values and Salt Concentration

Summary: Bovine serum albumin imprinted calcium phosphate/alginate hydrogel microspheres were prepared with sodium alginate (SA), (NH₄)₂HPO₄, and using CaCl₂ as gelling agent, bovine serum albumin (BSA) as template in inverse suspension. The optimized rebinding properties of BSA imprinted hydrogel microspheres were investigated by controlling pH value and ionic concentration from the viewpoint of adjusting the process of gelling, removing template and rebinding. The optimized pH values for the imprinting of BSA in gelling, removing template and rebinding process was 4.1, 8.3 and 4.8, respectively. The effect of NaCl concentration on the BSA rebinding was also determined. We provided a strategy to get the optimized imprinting efficiency by altering pH value and ionic concentration in a weakly ionic cross-linked hydrogel system on the process of protein's imprinting.     

The effect of polymeric supports and methods of immobilization on the performance of an optical copper(II)-sensitive membrane based on the colourimetric reagent Zincon

A comparative study on the effect of different immobilization methods and matrix materials on the performance of copper(II)-sensitive membrane layers is presented. The indicator dye Zincon was immobilized in hydrophilic and hydrophobic polymers by various methods including: (a) physical entrapment of the Zincon-tetraoctylammonium ion pair in plasticized PVC, hydrogel, polystyrene, ethyl cellulose, poly-HEMA, AQ-polymer and in sol-gel glass; (b) electrostatic immobilization on an anion exchanger cellulose; and (c) covalent immobilization on cellulose via a sulfatoethylsulfonyl reactive group. The response to copper(II) ion was evaluated kinetically via the initial slope of the change in absorbance within 1 min. Layers made of hydrogel and PVC provide the highest sensitivity, while covalent immobilization is the most reproducible one, and sol-gel layers display the best mechanical stability.     

γ-irradiated chitosan-polyvinyl pyrrolidone hydrogels as pH-sensitive protein delivery system

The effects of pH of the buffer solution and the composition of the hydrogel system on the bovine serum albumin (BSA) adsorption capacity of chitosan (CS)–polyvinyl pyrrolidone (PVP) (CSPVP) hydrogels and release of BSA were investigated. Poly-electrolyte CSPVP hydrogels with different compositions were prepared by irradiating CS/PVP/water mixtures with γ-rays at ambient temperature. The adsorption capacity of hydrogels was found to increase from 0 to 350 mg BSA/g dry gel, by changing external stimuli and hydrogel composition. The adsorption of BSA within CSPVP hydrogels increased with increase in CS content in the hydrogels. When the irradiation doses of hydrogel increased, the adsorption of BSA decreased. The maximum adsorption of BSA was observed at pH 5. A significant amount of the adsorbed BSA (up to 95%) was eluted in the phosphate medium containing 0.1 M NaCl at pH 7.4.     

Preparation and characterization of liposomes-in-alginate (LIA) for protein delivery system

This paper describes the preparation and characterization of a novel drug delivery system for protein, liposomes-in-alginate (LIA) of biodegradable polymers, which is conceived from a combination of the polymer and the lipid-based delivery systems. LIA were prepared by first entrapping bovine serum albumin (BSA), a model protein within multivesicular liposomes (MVLs) by double emulsification process, which are then encapsulated within alginate hydrogel microcapsule, with untrapped BSA which are added during preparation of MVLs. Factors impacting encapsulation efficiency of MVLs are investigated and release of protein from the microcapsules in vitro is studied. At the same time, characterization of MVLs, microcapsules encapsulated protein formulation and integrality analyse of BSA in microcapsules are also studied, with the aim of improving the entrapment efficiency and prolonging release time. It is found that encapsulation efficiency and size of MVLs are affected by the composition and fabrication parameters of LIA. The data also show LIA have high encapsulation efficiency (up to 95%), little chemical change in drug caused by the formulation process, narrow particle size distribution and spherical particle morphology. Drug release assays conducted in vitro indicates that these formulations provide sustained release of encapsulated drug over a period, about 2 weeks.     

牛血清白蛋白与Cu(Ⅱ)、Cu(Ⅰ)相互作用的表面电化学研究

采用循环伏安法,研究了牛血清白蛋白(BSA)吸附到玻碳电极上构成的BSA修饰电极.考察了铜离子在BSA修饰电极上的电化学行为.结果表明,Cu(Ⅱ)、Cu(Ⅰ)通过非疏水(静电或者共价)作用与电极表面的BSA结合,Cu~(2+)在BSA修饰电极上与BSA的结合能力比Cu~+与BSA的结合能力强,使用该方法探究蛋白与金属离子、小分子的作用是可行的.     

Pore-covered thermoresponsive membranes for repeated on-demand drug release

Reversible on/off-switching of bovine serum albumin (BSA) permeation through a thermoresponsive composite membrane with negligible permeation in the off-state is demonstrated. UV-photografting of poly(N-isopropylacrylamide) onto a poly(ethylene terephthalate) microfiltration membrane results in a hydrogel graft layer on the irradiated side of the membrane only. The amount of hydrogel grafted onto the membrane can be controlled by the amount of crosslinker. Above the lower critical solution temperature (LCST) of the hydrogel (on-state), the shrunken state of the graft layer appears to only partially cover the membrane, allowing BSA permeation through the uncovered pores. Provided the grafting degree is high enough, the swollen hydrogel covers the membrane completely below the LCST (off-state), thus preventing BSA permeation. The on-demand release mechanism proposed here is based on switching the membrane surface coverage rather than previously reported switches based on effective pore size or hydrogel mesh size. The main advantage of our mechanism is that higher fluxes can be achieved in the on-state, since permeation is not limited by pore-narrowing.     

In situ metal particle preparation in cross-linked poly(2-acrylamido-2-methyl-1-propansulfonic acid) hydrogel networks

Anionic hydrogels of poly(2-acrylamido-2-methyl-1-propansulfonic acid) (p(AMPS)) were prepared with a different amount of cross-linker extent and used for in situ preparation of magnetic and metal particles. The metal particles with various sizes were obtained inside the three-dimensional polymer matrixes by absorption of the corresponding metal ions from their aqueous solutions followed by the reduction in the presence of strong reducing agent. In addition to iron particles, cobalt, nickel, copper nanoparticles, and CdS, quantum dot has been prepared by utilizing hydrogel matrix as a template for inorganic/organic composite synthesis. It was observed that the amount of cross-linkers (0.5%, 0.75%, and 1% with respect to monomer mole ratio) used in this study for bare p(AMPS) has not significantly influenced the morphology of the hydrogels or the size of the iron particles while having great effect on swelling of p(AMPS) hydrogels in water. Copolymeric hydrogels of AMPS with acrylamide in different composition were also prepared. Thermogravimetric analysis and transmission electron microscopy results showed that the AMPS content of the copolymeric hydrogel has great impact on both the metal ion loading capacity and the size of the resultant metal particles.     

Micropatterning of proteins on the surface of three-dimensional poly(ethylene glycol) hydrogel microstructures

This paper describes micropatterning of proteins on the surface of three-dimensional hydrogel microstructures. Poly(ethylene glycol) (PEG)-based hydrogel microstructures were fabricated on a glass substrate using a poly(dimethylsiloxane) (PDMS) replica as a molding insert and photolithography. The lateral dimension and height of the hydrogel microstructures were easily controlled by the feature size of the photomask and depth of the PDMS replica, respectively. Bovine serum albumin (BSA), a model protein, was covalently immobilized to the surface of the hydrogel microstructure via a 5-azidonitrobenzoyloxy N-hydroxysuccinimide bifunctional linker at a surface density of 1.48 mg cm⁻². The immobilization of BSA on the PEG hydrogel surface was demonstrated with XPS by confirming the formation of a new nitrogen peak, and the selective immobilization of fluorescent-labeled BSA on the outer region of the three-dimensional hydrogel micropattern was demonstrated by fluorescence. A hydrogel microstructure could immobilize two different enzymes separately, and sequential bienzymatic reaction was demonstrated by reacting glucose and Amplex Red with a hydrogel microstructure where glucose oxidase was immobilized on the surface and peroxidase was encapsulated. Activity of immobilized glucose oxidase was 16.5 U mg⁻¹, and different glucose concentration ranged from 0.1 to 20 mM could be successfully detected.     

New semi-interpenetrating network hydrogels: synthesis, characterization and properties

Amphiphilic hydrogels composed of aliphatic polyesters and poly(ethylene glycol) have potential applications in drug delivery, tissue engineering and other biomedical devices due to their advantageous biological properties, biocompatibility and biodegradability. However, they also exhibit some shortcomings in terms of their reactivity, swelling and mechanical properties. To address these limitations, new semi-interpenetrating network (semi-IPN) hydrogels based on poly(ethylene glycol)-co-poly(epsilon-caprolactone) (PEG-PCL) diacrylate macromer and hydroxypropyl guar gum (HPGG) were prepared by a low intensity ultraviolet (UV) light irradiation method, and characterized by FT-IR, DSC and WAXD analysis. Their properties were evaluated by investigating the swelling kinetics, dynamic mechanical rheology and the release behavior for bovine serum albumin (BSA). It was found that the introduction of the semi-IPN structure and HPGG decreased the crystallinity of PEG segments in the hydrogel, and improved the swelling and mechanical properties of the hydrogel, as well as lowered the release percentage of BSA from the hydrogel. Such hydrogel materials may have more advantages as a potentially interesting platform for the design of medical devices.The elastic modulus (G') and viscous modulus (G') as a function of frequency for various hydrogel samples.     

Thermosensitive molecularly imprinted hydrogel cross‐linked with N‐malely chitosan for the recognition and separation of BSA

A novel temperature‐sensitive molecularly imprinted hydrogel composed of N‐isopropylacrylamide and acrylamide has been prepared by using free‐radical polymerization and was cross‐linked by modified water‐soluble N‐maley chitosan in aqueous solution. BSA (pI 4.9, MW 66.0 kDa) was used as the template protein. The produced hydrogels were characterized by environmental SEM to reveal the microcosmic morphology. A microporous structure was only found in the imprinted hydrogel, while no obvious microporous structure was found in nonimprinted hydrogels. The lower critical solution temperature of the hydrogels was 34°C, and the optimal binding conditions were tested, namely, the adsorption equilibrium time of 6 h and initial BSA concentration of 1.0 mg/mL. The adsorption capacity Q_max was determined by Langmuir isotherm plots and was 5.72 mg/g for imprinted hydrogel and 1.18 mg/g for nonimprinted hydrogels. A separation factor (β) of 4 was obtained when bovine hemoglobin (pI 6.9, MW 64.0 kDa) was selected as the particular reference protein. Molecular weights and pIs were chosen to investigate the selectivity of the hydrogels. It was shown that the shape memory and the size effect were the major factors for the recognition. This imprinted hydrogel was used to specifically adsorb the BSA from the protein mixture.     

铜纳米簇的制备、聚集诱导荧光增强性能及应用研究进展

铜纳米簇不仅具有金属纳米簇的特异性,还有前驱体价格便宜等优点,因此有广泛的应用前景。从配体辅助法、模板法、微波法、电化学法和刻蚀法等综述了铜纳米簇的制备方法。从离子诱导聚集、pH诱导聚集、组装诱导聚集和溶剂诱导聚集增强发射等方面综述了铜纳米簇聚集诱导荧光发射增强性能。从离子检测、小分子检测、酶活性检测、生物大分子检测和生物成像等方面综述了铜纳米簇的应用,并对铜纳米簇的制备、性能优化和应用等方面作了展望。