Preparation and characterization of galactosylated bovine serum albumin nanoparticles for liver-targeted delivery of oridonin

In this study, galactosylated bovine serum albumin (GB), which could be developed for a liver targeting carrier was synthetized and it was identified by Fourier transform infrared (FT-IR) spectrometer. Oridonin loaded bovine serum albumin nanoparticle (ORI-BSA-NP) and oridonin loaded GB nanoparticle (ORI-GB-NP) were prepared and optimized by the desolvation technique. During the preparation of ORI-GB-NP, galactosamine was introduced to end-cap the free aldehyde groups on nanoparticles. The characteristics of ORI-GB-NP such as particle size, zeta potential, particle morphologie, entrapment efficiency and drug loading were evaluated. The nearly spherical nanoparticles, with a narrow size distribution below 200 nm, were negatively charged with zeta potential of about −30 mV. Meanwhile, differential scanning calorimetry (DSC) and X-ray diffraction confirmed the amorphous state of ORI in ORI-GB-NP. The in vitro drug release of ORI from ORI-GB-NP presented a biphasic pattern with an initial burst effect and consequently sustained release. These results implied that the nanoparticles possessed fine physicochemical characteristics and seemed to be a stable delivery system for poorly soluble oridonin.     

冬凌草甲素固态类脂纳米粒在小鼠体内的组织分布及兔体内的药代动力学

目的考察冬凌草甲素固态类脂纳米粒在动物体内的组织分布及药代动力学特性。方法建立生物样品中冬凌草甲素的HPLC测定法，比较冬凌草甲素普通注射液和固态类脂纳米粒注射液的体内分布特点与药代动力学参数。结果冬凌草甲素固态类脂纳米粒在肝、脾、肺、心及肾中的相对摄取率分别为4.25%，3.44%，1.19%，0.52%和0.60%。静脉注射后的药-时曲线表明体内过程符合三室模型，其各相半衰期分别为T_1/2π=0.087 h，T_1/2α=1.65 h，T_1/2β=32.36 h，中心分布容积V_C=0.66 mL·kg^-1。结论冬凌草甲素固态类脂纳米粒能够增强药物的肝脾靶向性，提高药物生物利用度，并在一定程度上延长药物在动物体内的循环时间。固态类脂纳米粒可能成为冬凌草甲素的一种新型药物载体。     

大黄素甲醚和牛血清蛋白相互作用的电化学性质研究

在pH4.0的Britton-Robinson(B-R)缓冲体系中,应用循环伏安法和示差脉冲伏安法对大黄素甲醚与牛血清白蛋白(BSA)相互作用的电化学性质进行研究。结果表明,二者结合生成了一种非电活性的超分子化合物,同时对结合反应的机理进行了探讨。BSA的存在导致大黄素甲醚氧化还原峰电流降低,峰电位基本不变,峰电流的下降值同所加入的BSA浓度在一定范围内呈线性关系。线性范围5.0×10-6~1.0×10-7mol/L,检出限3×10-7mol/L。     

Preparation and characterization of Pingyangmycin-loaded bovine serum albumin microspheres for embolization therapy

Bovine serum albumin microspheres (BSA-MSs) containing Pingyangmycin hydrochloride (PYM) were prepared for the interventional embolization by an emulsification-crosslinking method. The average diameter of the MSs was 83.6 microm with 80% ranging from 35 to 200 microm. The MSs showed a rather high entrapment efficiency (EE%) of 87.6+/-5.7% and the drug loading efficacy (DL%) was 20.2+/-1.3%. The drug release behaviors were evaluated both in vitro and in vivo, using UV-spectroscopy and HPLC, respectively. The in vitro results showed a significantly delayed release of drug for 10 days. The central auricular artery of rabbit was chosen as an embolization sites to study the in vivo drug release and the pharmacokinetics of the MSs compared with PYM injections. Experiments performed by artery perfusion and embolization in rabbits central auricular artery revealed that the PYM loaded BSA-MSs (PYM-BSA-MSs) could obviously prolong in vivo drug release, extend the mean residence time (MRT) and had equal bioavailability compared with plain PYM injections. These results demonstrated that by embolization of the central auricular artery with PYM-BSA-MSs, the local drug concentration could maintain at a relative high level for a longer time, thus achieve the aim of tumor targeting therapy. PYM-BSA-MSs are excellent potential alternatives of interventional embolization materials for the treatment of maxillofacial region tumors.     

Physicochemical studies of dinitrophenylated bovine serum albumin

The structural changes of bovine serum albumin (BSA) as a function of dini-trophenylation have been studied by disc gel electrophoresis, sedimentation velocity analyses, and circular dichroism. These experiments were designed to understand the molecular bases for the change in immunogenicity and antigenicity of BSA upon dinitrophenylation. Dinitrophenylated BSA tends to aggregate to dimers and higher aggregates. A concomitant large change in electrophoretic mobility was also observed. Circular dichroism studies reveal a large decrease in the α-helical structure of the BSA molecule.     

荧光光谱法研究忍冬苷与牛血清白蛋白的相互作用

本文首次采用荧光光谱法研究了忍冬瞢与牛血清白费白（BSA）在模拟人体生理条件下的相互作用。结果表明忍冬苷对BSA的荧光猝灭作用属于静态猝灭．且296K下结合常数Ka为3．82×10^-5L·mol^-1,结合位点数n为1．16;热力学分析表明二者主要靠氢键和范德华力结合;位点竞争实验则显示忍冬苷主要通过Site I与BSA相结合;最后还考察了几种常见的共存离子对相互作用的影响。     

Molecular spectroscopic studies on the interaction between Ractopamine and bovine serum albumin

To investigate the interaction between Ractopamine (RAC), an animal growth promoter, and bovine serum albumin (BSA), three spectroscopic approaches (fluorescence, UV–vis and FT-IR) and three different experiments (two mole-ratio and a Job's methods) were used to monitor the biological kinetic interaction procedure. The Stern–Volmer quenching constants K_SV, the binding constants K_a, and the number of binding sites n at 298, 301 and 304 K were evaluated by molecular spectroscopic approaches. The values of enthalpy (−13.47 kJ mol⁻¹) and entropy (78.39 J mol⁻¹ K⁻¹) in the reaction indicated that RAC bound to BSA mainly by electrostatic and hydrophobic interaction. The site markers competitive experiments indicated that the binding of RAC to BSA primarily took place in site I. The spectra data matrix was further investigated with multivariate curve resolution-alternating least squares (MCR-ALS), and the concentration profiles and the pure spectra for three species (BSA, RAC and RAC-BSA) existed in the kinetic interaction procedure, as well as the apparent equilibrium constants, were obtained.     

Spectroscopic studies on the interaction between silicotungstic acid and bovine serum albumin

The interaction between silicotungstic acid and bovine serum albumin (BSA) was investigated using fluorescence and UV/vis. The experimental results showed that the fluorescence quenching of BSA by silicotungstic acid is a result of the formation of SiW–BSA complex; static quenching and non-radiative energy transferring were confirmed to result in the fluorescence quenching. The binding site number n, apparent binding constant K_A and corresponding thermodynamic parameters were measured at different temperatures. The process of binding SiW molecule on BSA was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased. Hydrophobic interaction force plays a major role in stabilizing the complex. The effect of silicotungstic acid on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy.     

亚甲蓝类似物的合成及其与牛血清白蛋白相互作用的研究

目的 合成3种亚甲蓝类似物3,7-二(二正丙胺基)-吩噻嗪-5-鎓碘化物、3,7-二(二正丁胺基)-吩噻嗪-5-鎓碘化物和3,7-二(二正戊胺基)-吩噻嗪-5-鎓碘化物,并研究模拟生理条件下这3种亚甲蓝类似物与牛血清白蛋白的相互作用.方法 通过1H-NMR及MS对这3种亚甲蓝类似物进行结构表征,应用荧光光谱法研究了模拟生理条件下这3种亚甲蓝类似物与牛血清白蛋白的相互作用.结果 3种亚甲蓝类似物和BSA相互作用形成了蛋白质-药物复合物并猝灭其固有荧光,亚甲蓝类似物与BSA相互作用过程的ΔG0<0,亚甲蓝类似物与BSA荧光残基间的距离r均小于7 nm.结论 亚甲蓝类似物和BSA相互作用的猝灭机制为静态猝灭,二者之间的反应是自发进行的.非辐射能量转移理论表明BSA与亚甲蓝类似物之间存在非辐射能量转移.同步荧光光谱和三维荧光光谱的研究结果表明,亚甲蓝类似物与BSA的相互作用导致BSA构象发生变化.     

Analysis of binding interaction between puerarin and bovine serum albumin by multi-spectroscopic method

The interaction of puerarin and bovine serum albumin (BSA) was investigated by means of fluorescence spectroscopy, resonance light-scattering spectroscopy, infrared spectroscopy, and synchronous fluorescence spectra. The apparent binding constants (K(a)) between puerarin and BSA were 1.13 x 10(4) (20 degrees C), and 1.54 x 10(4) lmol(-1) (30 degrees C), and the binding sites values (n) were 0.95+/-0.02. The experimental results showed that the puerarin could be inserted into the BSA, quenching the inner fluorescence by forming the puerarin-BSA complex. The addition of increasing puerarin to BSA solution leads to the gradual decrease in RLS intensity, exhibiting the formation of the aggregate in solution. It was found that both static quenching and non-radiation energy transfer were the main reasons for the fluorescence quenching. The positive entropy change and enthalpy change indicated that the interaction of puerarin and BSA was driven mainly by hydrophobic forces. The process of binding was a spontaneous process in which Gibbs free energy change was negative. The competing binding reaction with BSA between Fe(3+), Cu(2+) and puerarin was investigated. The effect of Fe(3+) and Cu(2+) on the binding of puerarin with BSA is discussed.     

Surface modification of PLGA nanoparticles via human serum albumin conjugation for controlled delivery of docetaxel

Background

Poly lactic-co-glycolic acid (PLGA) based nanoparticles are considered to be a promising drug carrier in tumor targeting but suffer from the high level of opsonization by reticuloendothelial system due to their hydrophobic structure. As a result surface modification of these nanoparticles has been widely studied as an essential step in their development. Among various surface modifications, human serum albumin (HSA) possesses advantages including small size, hydrophilic surface and accumulation in leaky vasculature of tumors through passive targeting and a probable active transport into tumor tissues.

Methods

PLGA nanoparticles of docetaxel were prepared by emulsification evaporation method and were surface conjugated with human serum albumin. Fourier transform infrared spectrum was used to confirm the conjugation reaction where nuclear magnetic resonance was utilized for conjugation ratio determination. In addition, transmission electron microscopy showed two different contrast media in conjugated nanoparticles. Furthermore, cytotoxicity of free docetaxel, unconjugated and conjugated PLGA nanoparticles was studied in HepG2 cells.

Results

Size, zeta potential and drug loading of PLGA nanoparticles were about 199 nm, −11.07 mV, and 4%, respectively where size, zeta potential and drug loading of conjugated nanoparticles were found to be 204 nm, −5.6 mV and 3.6% respectively. Conjugated nanoparticles represented a three-phasic release pattern with a 20% burst effect for docetaxel on the first day. Cytotoxicity experiment showed that the IC50 of HSA conjugated PLGA nanoparticles (5.4 μg) was significantly lower than both free docetaxel (20.2 μg) and unconjugated PLGA nanoparticles (6.2 μg).

Conclusion

In conclusion surface modification of PLGA nanoparticles through HSA conjugation results in more cytotoxicity against tumor cell lines compared with free docetaxel and unconjugated PLGA nanoparticles. Albumin conjugated PLGA nanoparticles may represent a promising drug delivery system in cancer therapy.     

灯盏乙素与牛血清白蛋白相互作用的研究

目的采用荧光、紫外光谱法研究在模拟人体生理条件下灯盏乙素与牛血清白蛋白(BSA)之间的相互作用。方法将灯盏乙素对牛血清白蛋白进行荧光淬灭滴定,利用Scatchard模型和F"rster非辐射能量转移理论得出灯盏乙素和牛血清白蛋白的结合参数。结果灯盏乙素与BSA的结合常数K=1.240×106,结合距离r=2.94nm,相互作用力主要为疏水作用力。结论阐明了灯盏乙素和牛血清白蛋白相互作用的机制,建立了灯盏乙素和牛血清白蛋白的结合模型。     

肝细胞靶向甘草酸表面修饰白蛋白纳米粒的制备工艺

目的研究能主动靶向于肝实质细胞的甘草酸表面修饰白蛋白纳米粒的制备工艺。方法去溶剂化法制备普通纳米粒，以高碘酸盐氧化法制备甘草酸-白蛋白纳米粒偶联物。用2,4,6-三硝基苯磺酸显色法与凝胶柱色谱法验证是否偶联成功，HPLC法测定修饰纳米粒表面甘草酸密度。结果修饰纳米粒表面活性氨基数量较对照组减少19.6%；偶联于纳米粒表面的甘草酸密度为9.2%。纳米粒形态圆整，平均粒径为73 nm，在25 ℃和37 ℃条件下放置10 d后，性质稳定。结论甘草酸表面修饰白蛋白纳米粒制备成功，为进一步研究其对肝细胞的靶向性奠定了实验基础。     

Binding of Sudan II and Sudan IV to bovine serum albumin: Comparison studies

In this paper, we report the interaction of Sudan II and Sudan IV to bovine serum albumin (BSA). Structural analysis showed that both Sudan II and Sudan IV interact mainly with BSA at the hydrophobic pocket and via Van der Waals forces. The number of bound Sudan molecule for each protein molecule was approximately 1. The overall binding constants at 293 K (20 °C) estimated for Sudan II and Sudan IV were 1.22 × 10⁴ M⁻¹ and 1.48 × 10⁴ M⁻¹, respectively. BSA backbone structure was damaged by the dyes with more severe phenomenon observed for Sudan IV. For two Sudan dyes with the same concentration, Sudan IV could cause more alterations on CD spectra of BSA with slight decrease of α-helical content and increase of β-sheet content, suggesting a partial protein unfolding.     

超声波激活氧氟沙星声动力损伤牛血清白蛋白的研究

目的 考察Fe3+、Zn2+金属离子(Mn+)对于超声波激活氧氟沙星(OFX)损伤牛血清白蛋白(BSA)的影响.方法 采用紫外-可见光谱和荧光光谱,探讨了超声照射时间和Fe3+、Zn2+金属离子浓度等因素对牛血清白蛋白损伤的影响.结果 在一定条件下,牛血清白蛋白的损伤程度随超声波照射时间的延长和Fe3+、Zn2+浓度的增大而加剧,并且Fe3+对于超声激活氧氟沙星损伤牛血清白蛋白的促进作用明显强于Zn2+.结论 Fe3+可明显增强超声波激活氧氟沙星对牛血清白蛋白的损伤.     

Multiple spectroscopic studies on the interaction between olaquindox,a feed additive,and bovine serum albumin

The interaction between olaquindox (OLA) and bovine serum albumin (BSA) was investigated using fluorescence, UV–vis absorption and circular dichroism (CD) spectroscopy. The results showed that the fluorescence quenching of BSA by OLA was a static quenching process induced by the formation of OLA–BSA complex. The binding constant of OLA–BSA complex was calculated to be 1.299 × 10⁴ L mol⁻¹ (293 K). The negative values of ΔH⁰ and ΔS⁰ indicated that hydrogen bond and van der Waals interactions played major roles in stabilizing the complex. Site probe competition experiments and number of binding sites (n) revealed that OLA could bind to site I in subdomain IIA of BSA, and the binding distance (r) was evaluated to be 3.643 nm according to Förster’s non-radiative energy transfer theory. The results of CD and three-dimensional fluorescence spectra suggested some conformational changes of BSA after OLA binding.     

Selection of an analytical method for evaluating bovine serum albumin concentrations in pharmaceutical polymeric formulations

Bovine serum albumin (BSA) is a commonly used model protein in the development of pharmaceutical formulations. In order to assay its release from various dosage forms, either the bicinchoninic acid (BCA) assay or a more specific size-exclusion high performance liquid chromatography (SE-HPLC) method are commonly employed. However, these can give erroneous results in the presence of some commonly used pharmaceutical excipients. We therefore investigated the ability of these methods to accurately determine BSA concentrations in pharmaceutical formulations that also contained various polymers and compared them with a new reverse-phase (RP)-HPLC technique. We found that the RP-HPLC technique was the most suitable method. It gave a linear response in the range of 0.5–100 μg/ml with a correlation co-efficient of 0.9999, a limit of detection of 0.11 μg/ml and quantification of 0.33 μg/ml. The performed ‘t’-test for the estimated and theoretical concentrations indicated no significant difference between them providing the accuracy. Low % relative standard deviation values (0.8–1.39%) indicate the precision of the method. Furthermore, the method was used to quantify in vitro BSA release from polymeric freeze-dried formulations.     

Interaction of isoliquiritigenin with bovine serum albumin studied by fluorescence quenching method

Interaction of ioliquiritigenin (ISL), which is the main active component of a commonly used traditional Chinese medicine (TCM) Glycyrrhiza uralensis Fisch. with bovine serum albumin (BSA) has been investigated. The quenching mechanism of fluorescence of bovine serum albumin by ISL was discussed. The binding sites number n and apparent binding constant K were measured by fluorescence quenching method. The thermodynamic parameters ΔH⁰, ΔG⁰, ΔS⁰ at different temperatures were calculated. The distance r between donor (bovine serum albumin) and acceptor (ISL) was obtained according to Förster theory of non-radiation energy transfer. The results of synchronous fluorescence spectra and UV-vis absorption spectra show that the conformation of bovine serum albumin has been changed.     

Chitosan-coated bovine serum albumin nanoparticles for topical tetrandrine delivery in glaucoma: in vitro and in vivo assessment

Glaucoma is one of the leading causes of blindness. Therapies available suffer from several drawbacks including low bioavailability, repeated administration and poor patient compliance with adverse effects thereafter. In this study, bovine serum albumin nanoparticles (BSA-NPs) coated with chitosan(CS) were developed for the topical delivery of tetrandrine (TET) for glaucoma management. Optimized nanoparticles were prepared by desolvation. pH, BSA, CS and cross-linking agent concentrations effects on BSA-NPs colloidal properties were investigated. CS-BSA-NPs with particle size 237.9 nm and zeta potential 24 mV was selected for further evaluation. EE% exceeded 95% with sustained release profile. In vitro mucoadhesion was evaluated based on changes in viscosity and zeta potential upon incubation with mucin. Ex vivo transcorneal permeation was significantly enhanced for CS coated formulation. In vitro cell culture studies on corneal stromal fibroblasts revealed NPs biocompatibility with enhanced cellular uptake and improved antioxidant and anti-proliferative properties for the CS-coated formulation. Moreover, BSA-NPs were nonirritant as shown by HET-CAM test. Also, bioavailability in rabbit aqueous humor showed 2-fold increase for CS-TET-BSA-NPs compared to TET with a sustained reduction in intraocular pressure in a rabbit glaucoma model. Overall, results suggest CS-BSA-NPs as a promising platform for topical ocular TET delivery in the management of glaucoma.