Adsorption of BSA on QAE-dextran: equilibria

Equilibrium isotherms for adsorption of bovine serum albumin (BSA) on a strong-base (QAE) dextran-type ion exchanger have been determined experimentally. They were not affected by the initial concentration of BSA but were affected by pH considerably. They were correlated by the Langmuir equation when pH >/= 5.05 and by the Freundlich equation of pH 4.8, which is close to pl approximately 4.8 of BSA. The contribution of ion exchange to adsorption of BSA on the ion exchanger was determined experimentally. The maximum amounts of inorganic anion exchanged for BSA were 1% and 0.4% of the exchange capacity of the ion exchanger at pH 6.9, respectively. Since the effect of the ion exchange on the adsorption appeared small, BSA may be adsorbed mainly by electrostatic attraction when pH >/= 5.05 and by hydrophobic interaction or hydrogen bonding at pH 4.8. When NaCl coexisted in the solution, the shape of the isotherm was similar to the Langmuir isotherm, but it is shifted to the right. When the concentration of NaCl was 0.2 mol/dm(3), BsA was not adsorbed on the resin. When BSA was dissolved in pure water, the saturation capacity of BSA on HPO(4) (2-),-orm resin was about 2 times larger than that for adsorption from the solution with buffer (pH 6.9 and 8.79). The saturation capacity for adsorption of BSA in pure water on HPO(4) (2-) + H(2)O(4) (-)-from resin was much smaller than that from the solution with buffer. The isotherms for univalent Cl(-)-and H(2)PO(4) (-)-form resin was peculiar; that is, the amount of BSA adsorbed decreased with increasing the liquid-phase equilibrium concentration of BSA. (c) 1993 John Wiley & Sons, Inc.     

界面上配基种类对BSA吸附行为的影响

利用双偏振极化干涉测量仪(DPI)研究了界面上配基种类对BSA吸附行为的影响。采用3-氨基丙基三乙氧基硅烷(APTES)、3-(甲氨基)丙基三甲氧基硅烷(MAPTMS)和N,N-二乙基-3-氨基丙基三甲氧基硅烷(DAPTMS)对DPI芯片进行了修饰,利用X射线光电子能谱比较了芯片上不同配基的密度,采用原子力显微镜(AFM)和DPI对界面上BSA吸附行为进行了研究。结果表明APTES修饰界面上BSA呈饼状,高配基密度易导致BSA多位点吸附。相同偶联密度条件下BSA在DAPTMS修饰芯片的吸附量高于MAPTMS修饰芯片,但吸附层厚度一致,表明DAPTMS表面上BSA存在聚集现象;AFM扫描结果与DPI分析结果一致,证明了配基密度和种类不仅影响界面上蛋白质吸附量,而且影响蛋白质吸附密度和表面聚集行为。     

Adsorption of Ni2+ on the surface of molecularly imprinted adsorbent from Penicillium chysogenum mycelium

The adsorption capacity for Ni²⁺ on to the surface molecular imprinting adsorbent on Penicillium chysogenum mycelium (the surface-imprinted adsorbent) was 40–45 mg g^–1 (using 200 mg Ni²⁺ l^–1), two times of the mycelium adsorbent. The surface-imprinted adsorbent had good stability at pH 28. The optimal concentration of EDTA for desorption was 0.1 to 0.5 g l^–1. The surface imprinted adsorbent could be reused 15 times without losing its uptake.     

壳聚糖抑菌机制的初步研究

壳聚糖在医学、食品、环保、日化用品等领域有着广泛而重要的应用.近年来,壳聚糖由于对不同的菌类都具有良好的抑菌效果而被研究者们密切关注.然而,有关壳聚糖抑菌机制的研究却并不多,其抑菌机制也没有被完全阐明.在本研究中,我们发现很多金属离子可以对壳聚糖的抑菌效果产生影响,高浓度金属离子(0.5%)可以使壳聚糖完全丧失抑菌活性.还发现金黄色葡萄球菌和白色念珠菌在壳聚糖的作用下会发生钾离子和ATP的渗漏,而且五万分子量的壳聚糖引起钾离子和ATP的渗漏大约比五千分子量壳聚糖多2到4倍.不同分子量的壳聚糖对金黄色葡萄球菌和白色念珠菌都具有较好的抑菌效果,但是引起钾离子和ATP的渗漏量却存在很大差异,这说明小分子量壳聚糖很可能存在与大分子量壳聚糖不同的抑菌机制.     

Enterovirus 71 adsorption on metal ion-composite chitosan beads

In this study, we developed composite chitosan beads combining various metal ions, including Ni(2+), Cu(2+), Zn(2+), and Fe(2+), for direct adsorption of enterovirus 71 (EV71). The metal-ion species had significant effects on the adsorption capacity of beads. Among these metal ion-composite chitosan beads, Ni(2+)-chitosan beads exhibited the best adsorption capacity of EV71. Using a concentration of 0.01-M Ni(2+) was found to best provide for bead formation and EV71 adsorption. The adsorption of EV71 for Ni(2+)-chitosan beads at neutral or alkaline pH was favored. Under a competitive condition with albumin proteins, Ni(2+)-chitosan beads exhibited significant capacity of EV71 adsorption in culture media. The adsorption of EV71 on the Ni(2+)-chitosan beads was attributed to the strong binding between Ni(2+) ions chelated to the surface amino acid of EV71 capsids and Ni(2+) ions chelated on the chitosan materials. Moreover, the adsorbed EV71 retained its antigenicity and infectivity after desorption. The Ni(2+)-chitosan beads exhibit a promising application to EV71 adsorption and removal.     

双波长法用于磺酸型树脂吸附BSA和trypsin的研究

考察了H^ 和Na^ 变化对紫外吸收单波长法、双波长法和考马斯亮蓝法的影响。结果表明双波长法比考马斯亮蓝法和单波长法稳定性要好。选择双波长法用于磺酸型离子交换树脂吸附胰蛋白酶(trypsin)和牛血清白蛋白(BSA)的检测,结果表明：交换容量为4-88mmol／g的树脂对BSA和trypsin的吸附速率和饱和吸附量均高于交换容量为3．17mmol／g的树脂。     

Characterization of decrystallized chitosan and its application in biosorption of textile dyes

Decrystallized chitosan was produced from shrimp shells with a low degree of crystallinity (10%) and a high anionic dye binding capacity. Raw, mixed dye wastewater from a textile factory was efficiently decolorized using decrystallized chitosan that was more efficient than using normal chitosan and activated carbon. Decolorization reached 90% within 10 min and could be carried out from pH 4.5 to 8.1. Decrystallized chitosan can be regenerated by 2 M H₂SO₄ and was reusable more than 10 times. It is, therefore, an attractive candidate for the removal of dyes from textile wastewater.     

Adsorption of avidin on microfabricated surfaces for protein biochip applications

The adsorption of the protein avidin from hen egg white on patterns of silicon dioxide and platinum surfaces on a microchip and the use of fluorescent microscopy to detect binding of biotin are described. A silicon dioxide microchip was formed using plasma-enhanced chemical vapor deposition while platinum was deposited using radiofrequency sputtering. After cleaning using a plasma arc, the chips were placed into solutions containing avidin or bovine serum albumin. The avidin was adsorbed onto the microchips from phosphate-buffered saline (PBS) or from PBS to which ammonium sulfate had been added. Avidin was also adsorbed onto bovine serum albumin (BSA)-coated surfaces of oxide and platinum. Fluorescence microscopy was used to confirm adsorption of labeled protein, or the binding of fluorescently labeled biotin onto previously adsorbed, unlabeled avidin. When labeled biotin in PBS was presented to avidin adsorbed onto a BSA-coated microchip, the fluorescence signal was significantly higher than for avidin adsorbed onto the biochip alone. The results show that a simple, low-cost adsorption process can deposit active protein onto a chip in an approach that has potential application in the development of protein biochips for the detection of biological species.     

Sulfanilic acid‐modified chitosan mini‐spheres and their application for lysozyme purification from egg white

A cation exchange matrix with zwitterionic and multimodal properties was synthesized by a simple reaction sequence coupling sulfanilic acid to a chitosan based support. The novel chromatographic matrix was physico‐chemically characterized by ss‐NMR and ζ potential, and its chromatographic performance was evaluated for lysozyme purification from diluted egg white. The maximum adsorption capacity, calculated according to Langmuir adsorption isotherm, was 50.07 ± 1.47 mg g^?1 while the dissociation constant was 0.074 ± 0.012 mg mL^?1. The process for lysozyme purification from egg white was optimized, with 81.9% yield and a purity degree of 86.5%, according to RP‐HPLC analysis. This work shows novel possible applications of chitosan based materials. The simple synthesis reactions combined with the simple mode of use of the chitosan matrix represents a novel method to purify proteins from raw starting materials. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:387–396, 2018     

Antifungal properties of Schiff bases of chitosan, N-substituted chitosan and quaternized chitosan

Schiff bases of chitosan, N-substituted chitosan, and quaternized chitosan were synthesized and their antifungal properties were analyzed against Botrytis cinerea Pers. (B. cinerea pers.) and Colletotrichum lagenarium (Pass) Ell.et halst (C. lagenarium (Pass) Ell.et halst) based on the method of D. Jasso de Rodríguez and co-workers. The results showed that quaternized chitosan had better inhibitory properties than chitosan, Schiff bases of chitosan, and N-substituted chitosan.     

壳聚糖改性竹炭对铜吸附性能研究

为了提高竹炭去除废水中重金属离子能力,采用交联法设计合成新型的磁性壳聚糖改性竹炭复合吸附剂,并采用傅里叶红外光谱对改性竹炭复合吸附剂进行表征,同时开展不同Cu2+初始浓度、吸附剂投加量、吸附时间、pH和温度等因素对Cu2+吸附去除率的影响。结果表明,吸附效率与Cu2+初始浓度和吸附剂投加量成正效应;吸附平衡时间约8 h;在作用温度范围内,吸附效率随温度升高而上升;pH为7时吸附效果最好。振荡条件吸附效果优于静置处理。该结果为废水重金属深度处理及水环境保护提供依据。     

Hydroxyl radicals scavenging activity of N-substituted chitosan and quaternized chitosan

N-substituted chitosan and quaternized chitosan were synthesized and their antioxidant activity against hydroxyl radicals was assessed, respectively. Compared with the antioxidant activity of chitosan, the results indicated that the two kinds of chitosan derivatives had different scavenging ability on hydroxyl radicals, which should be related to the form of amido in the two kinds of chitosan derivatives.     

Understanding the interaction of proteins to ion exchange chromatographic supports: A surface energetics approach

Ion exchange chromatography is one of the most widely used chromatographic technique for the separation and purification of important biological molecules. Due to its wide applicability in separation processes, a targeted approach is required to suggest the effective binding conditions during ion exchange chromatography. A surface energetics approach was used to study the interaction of proteins to different types of ion exchange chromatographic beads. The basic parameters used in this approach are derived from the contact angle, streaming potential, and zeta potential values. The interaction of few model proteins to different anionic and cationic exchanger, with different backbone chemistry, that is, agarose and methacrylate, was performed. Generally, under binding conditions, it was observed that proteins having negative surface charges showed strong to lose interaction (20 kT for Hannilase to 0.5 kT for IgG) with different anionic exchangers (having different positive surface charges). On the contrary, anionic exchangers showed almost no interaction (0–0.1 kT) with the positively charged proteins. An inverse behavior was observed for the interaction of proteins to cationic exchangers. The outcome from these theoretical calculations can predict the binding behavior of different proteins under real ion exchange chromatographic conditions. This will ultimately propose a better bioprocess design for protein separation.     

诺氟沙星与牛血清白蛋白相互作用的研究

用荧光光谱法研究诺氟沙星与牛血清白蛋白之间的结合作用,确定了诺氟沙星与牛血清白蛋白的荧光猝灭机制为静态猝灭。通过测定和计算不同温度下该结合反应的结合常数和结合位点数,并根据热力学方程求得了结合反应的热力学参数,讨论了两者问的主要作用力类型是范德华力和氢键。同时采用同步荧光技术考察了诺氟沙星对BSA构象的影响。并从荧光寿命进一步证明诺氟沙星与牛血清白蛋白的荧光猝灭机制为静态猝灭。     

Reactions of chitosan: 4. Preparation of organosoluble derivatives of chitosan

Fully subtituted di-O-acetyl-N-acetylchitosan (chitin diacetate) has been prepared by a route in which the hydroxyl groups are acetylated prior to N-acetylation. This overcomes the previously reported intramolecular steric hindrance to esterification caused by the N-acetamido group. The resultant products were of high viscosity but had a limited solubility range. Di-O-acrylcarbamate derivatives of N-acetylchitosan (chitin) have been produced by a similar route, whilst di-O-arylcarbamate-N-arylureidochitosans have been prepared directly from chitosan. These products also have limited solubility ranges and have inherent viscosities similar to that of di-O-acetylchitosan prepared from the same batch of chitosan.     

5-Fluorouracil-Loaded BSA Nanoparticles: Formulation Optimization and In Vitro Release Study

Over the past few decades, there has been considerable interest in developing protein nanoparticles as drug delivery devices. The underlying rationale is their exceptional characteristics, namely biodegradability and nonantigenicity. Herein, phase separation method was used to prepare 5-fluorouracil-loaded bovine serum albumin (BSA) nanoparticles. Drug release was tracked by continuous flow dialysis technique. Effect of process variables on loading efficiency of 5-fluorouracil was investigated and optimized through Taguchi’s M16 design with the amount of entrapped drug as response. Optimum condition was found to be 2 mg/mL of 5-fluorouracil, 3.7 mL of added ethanol, 176 μL of glutaraldehyde, drug–protein incubation time of 30 min, and pH of 8.4 for 200 mg of BSA in 2 mL drug solution. pH had the most noticeable effect on the amount of entrapped drug, but glutaraldehyde had the least. Mean diameter and zeta potential of fabricated nanoparticles under these conditions were 210 nm and −31.7 mV, respectively. Drug-loaded BSA nanoparticles suspension maintained constant release of drug for 20 h under experimental conditions, so this colloidal drug carrier is capable of releasing drug in a sustained manner.     

Adsorption of bovin serum albumin (BSA) onto the magnetic chitosan nanoparticles prepared by a microemulsion system

The adsorption characteristics of BSA onto the magnetic chitosan nanoparticles have been investigated in this paper. The magnetic chitosan nanoparticles were prepared by adding the basic precipitant of NaOH solution into a W/O microemulsion system. The morphology of magnetic chitosan nanoparticles was observed by transmission electron microscope (TEM). It was found that the diameter of magnetic chitosan nanoparticles was from 10nm to 20 nm, and the nanoparticles suspending in the aqueous solution could easily aggregate by a magnet, which suggested that the nanoparticles had good magnetic characteristics. The BSA adsorption experiment indicated that when pH of BSA solution was equal to 4, the maximum adsorption loading reached 110 mg/g. Through measuring the zeta potential of BSA solution and the magnetic nanoparticles, it was found that under this situation the surface of BSA took the negative charge, but the magnetic nanoparticles took the positive charge. Due to the small diameter, the adsorption equilibrium of BSA onto the nanoparticles reached very quickly within 10 min. The adsorption equilibrium of BSA onto the magnetic chitosan nanoparticles fitted well with the Freundlich model. The experimental results showed that the magnetic chitosan nanoparticles have potential to be used for the quick pretreatment in the protein analysis process.     

Adsorption and desorption surface dynamics of gaseous adsorbate on silicate-1 by molecular dynamics simulation

The dynamics of adsorption and desorption of gaseous molecules on the external surface of a crystal and a membrane of zeolite silicate-1 is investigated by molecular dynamics simulation. The gases are argon and three hydrocarbons, n-heptane, n-butane and ethylene. The sticking coefficient and the desorption coefficient are calculated for different coverages. The results clearly show that the desorption coefficients increase with the coverage contrary to the sticking coefficients. To have a better insight in the process, the desorption and adsorption time are computed, they are very similar and they show an increase with the coverage except for n-heptane which exhibit a specific decreasing behaviour at high loading.     

Expanded bed adsorption: elution in expanded bed mode

Elution in expanded bed mode has been investigated in the expanded bed adsorption process. Elution was performed at different sample loads and at different liquid velocities using bovine serum albumin as a model. The effect on mixing in the liquid phase and on the volume of the eluted peak were determined. Mixing in the liquid phase was almost unaffected when elution was performed at 100 cm/h, regardless of sample load. However, mixing increased significantly when elution was carried out at high liquid velocities (300 cm/h) at high sample loads. The eluted peak volume increased with liquid velocity and increased sample load. It was approx. 80% higher in expanded bed mode than in packed bed from an adsorbent completely saturated with protein eluted at 300 cm/h.     

超声和高压对牛血清白蛋白结构的影响比较

目的：研究牛血清白蛋白经过超声和高压处理前后的结构变化,以及自由基清除剂对其结构变化的影响。为进一步研究细胞破碎和乳化蛋白时超声和高压处理对蛋白的影响提供参考。方法：将BSA溶液经过超声和高压处理,然后利用高效液相色谱（HPLC）、动态光散射（DLS）、非变性聚丙烯酰胺凝胶电泳（nondenaturing SDS PAGE）以及园二色谱（CD）等手段检测处理前后的结构变化。结果：发现超声使BSA严重聚集,加入自由基清除剂可以减少聚集的产生。而高压处理后的BSA未出现聚集,但二级结构发生了变化。结论：超声和高压这两种处理方法对蛋白损伤机理不同,所以选择合适的破碎方法要根据蛋白自身的性质而定。