Homologous Assay Development for Detection of Dexamethasone using HRP as Label Enzyme

Background: Dexamethasone is a synthetic corticosteroid similar to cortisol produced naturally by the adrenal glands. As an anti- inflammatory and immunosuppressive agent, it is used in many diseases such as rheumatoid arthritis and allergic anaphylactic shock, and its suppression test to diagnose Cushing's syndrome. Its further use includes its administration before antibiotics in bacterial meningitis, antitumor treatment, for treatment of glucocorticoid resistance, Addison抯 disease, and congenital adrenal hyperplasia. The drug is abused by using it in animal husbandry as a growth promoter and in horse sports to enhance their performance. Methods: In this study, the development of homologous ELISA using Dexamethasone-21-hemisuccinate (DEX-21-HS)-Bovine serum albumin antiserum and Dexamethasone-21-hemisuccinate (DEX-21-HS)-Horseradish peroxidase enzyme conjugate has been done. The n-hydroxysuccinimide ester method was used to prepare the immunogen and enzyme conjugate. Results: The sensitivity 0.25 ng/mL, affinity 2.8x10-8 L/mol and ED50 4.98 ng/mL of the assay were found. The cross-reactivity of the assay was checked and found with three steroids (Corticosterone- 1.13%, Progesterone- 2.25% and Prednisolone- 6.3%) out of 48 structurally related steroids. Then, analytical variables of the developed assay were studied, such as recovery (98.55% to 105.08%), precision (Inter and Intra- assay coefficient of variation <9.28%), correlation (R2= 0.98) by utilizing a commercially available Dexamethasone kit for comparison. Conclusion: This study concluded that low-cost indigenous ELISA for Dexamethasone had been developed, which can give results within 75-80 minutes.

Preparation of cinnamaldehyde loaded liposomes bilayer-modified by bovine serum albumin/chitosan / 中国药房

OBJECTIVE To prepare cinnamaldehyde （CA） loaded liposomes bilayer-modified by bovine serum albumin （BSA）/chitosan （CTS）（BSA/CTS-Lip-CA） in order to improve the sustained-release effect and storage stability of the nanoparticles. METHODS Firstly，cinnamaldehyde loaded liposomes （Lip-CA）and blank liposomes （Lip-Blank）were prepared by thin film dispersion method. Then chitosan modified cinnamaldehyde loaded liposome （CTS-Lip-CA）and BSA/CTS-Lip-CA were obtained by electrostatic adsorption. Finally ， the prepared liposomes were characterized ， and their in vitro release characteristics and storage stability were investigated. RESULTS The particle size of BSA/CTS-Lip-CA was （177.8±4.0）nm and the Zeta potential was （－15.6±1.5）mV；they were in spherical shape ；FTIR analysis showed that the modification of BSA and CTS had no effect on the internal structure of liposomes. The results of in vitro drug release characteristics showed that the cumulative release of Lip-CA ，CTS-Lip-CA and BSA/CTS-Lip-CA within 10 hours were 82.9％，74.1％ and 72.9％ respectively. The results of storage stability showed that after 30 days of storage ，the particle sizes of Lip-CA ，CTS-Lip-CA and BSA/ CTS-Lip-CA were （134.2±2.1），（151.7±0.4），（164.8±1.5）nm；the retention rates of model drug CA were 65.4％，82.5％ and 90.2％ respectively. CONCLUSIONS BSA/CTS-Lip-CA is successfully prepared. It has a certain sustained-release effect and can improve the storage stability of the drug to a certain extent.

Effects of serum albumin on the photophysical characteristics of synthetic and endogenous protoporphyrin IX

The study of the interaction of synthetic protoporphyrin IX (PpIXs) and protoporphyrin IX extracted from Harderian glands of ssp Rattus novergicus albinus rats (PpIXe) with bovine serum albumin (BSA) was conducted in water at pH 7.3 and pH 4.5 by optical absorption and fluorescence spectroscopies. PpIXs is present as H- and J-aggregates in equilibrium with themselves and with monomers. The PpIXs charge is 2− at pH 7.3 and 1− at pH 4.5. This increases its aggregation at pH 4.5 and shifts the equilibrium in favor of J-aggregates. In spite of electrostatic attraction at pH 4.5, where BSA is positive, the binding constant (Kb) of PpIXs to BSA is 20% less than that at pH 7.3, where BSA is negative. This occurs because higher aggregation of PpIXs at pH 4.5 reduces the observed Kb value. At both pHs, water-soluble PpIXe exists in the monomeric form with the charge of 1− and its Kb exceeds that of PpIXs. At pH 4.5, its Kb is 12 times higher than that at pH 7.3 due to electrostatic attraction between the positively charged BSA and the negatively charged PpIXe. The higher probability of PpIXe binding to BSA makes PpIXe more promising as a fluorescence probe for fluorescence diagnostics and as a photosensitizer for photodynamic therapy. The existence of PpIXe in the monomeric form can explain its faster cell internalization. Aggregation reduces quantum yields and lifetimes of the PpIXs excited states, which explains higher phototoxicity of PpIXe toward malignant cells compared with PpIXs.

Effect of Fufang Shelong Capsules on Rats with Membranous Nephropathy Based on p38 MAPK Signaling Pathway / 中国实验方剂学杂志

ObjectiveTo investigate the nephroprotective and anti-inflammatory effects of Fufang Shelong capsules （FFSL） in rats with membranous nephropathy （MN）， and the role of the p38 mitogen-activated protein kinase （MAPK） signaling pathway. MethodMale SD rats of SPF grade were divided into a normal group and an experimental group. The MN model was induced by tail vein injection of cationized bovine serum albumin in the experimental group. After screening， the eligible model rats were included and divided into a positive control group （tripterygium glycosides tablets） and low-， medium-， and high-dose FFSL groups （0.375， 0.75， 1.5g·kg-1）. The rats were treated correspondingly for eight weeks， and urine protein was detected during drug intervention. Renal function and inflammation-related indicators were detected after drug intervention. The changes in 24-hour urine total protein （24 h UP）， interleukin-6 （IL-6）， interleukin-8 （IL-8）， tumor necrosis factor-α （TNF-α）， creatinine （Cr）， blood urea nitrogen （BUN）， total protein （TP）， albumin （Alb）， and total cholesterol （TC） were detected. Flow cytometry was used to detect CD4+/CD8+ changes. Kidney tissues were collected to observe pathological changes under a light microscope and an electron microscope. The protein expression of p38 MAPK and phosphorylated p38 MAPK （p-p38 MAPK） in kidney tissues was detected by Western blot. ResultCompared with the normal group， the model group showed increased 24 h UP （P<0.01）， elevated serum Cr， BUN， TC， IL-6， IL-8， and TNF-α （P<0.05，P<0.01）， decreased serum Alb and TP levels （P<0.05，P<0.01）， increased CD4+/CD8+ in the peripheral blood （P<0.01）， and up-regulated protein expression of p38 MAPK and p-p38 MAPK in kidney tissues （P<0.05）. Additionally， in the model group， immune complex deposition and foot process fusion， accompanied by infiltration of inflammatory cells， were observed on the epithelial side of the basement membrane in the pathological kidney tissues. Compared with the model group， the groups with drug intervention showed declining 24 h UP levels at six weeks （P<0.05，P<0.01）， decreased serum Cr， BUN， TC， IL-6， IL-8， and TNF-α （P<0.05，P<0.01）， increased serum Alb and TP levels （P<0.05，P<0.01）， reduced CD4+/CD8+ in the peripheral blood （P<0.01）， improved renal pathological damage， and down-regulated p38 MAPK and p-p38 MAPK in kidney tissues （P<0.05，P<0.01）. ConclusionFFSL can decrease the expression of inflammatory factors， reduce proteinuria， delay kidney damage， and protect kidney function by inhibiting the expression of the p38 MAPK signaling pathway.

Receptor-mediated targeted drug delivery systems for treatment of inflammatory bowel disease: Opportunities and emerging strategies

Inflammatory bowel disease (IBD) is a chronic intestinal disease with painful clinical manifestations and high risks of cancerization. With no curative therapy for IBD at present, the development of effective therapeutics is highly advocated. Drug delivery systems have been extensively studied to transmit therapeutics to inflamed colon sites through the enhanced permeability and retention (EPR) effect caused by the inflammation. However, the drug still could not achieve effective concentration value that merely utilized on EPR effect and display better therapeutic efficacy in the inflamed region because of nontargeted drug release. Substantial researches have shown that some specific receptors and cell adhesion molecules highly expresses on the surface of colonic endothelial and/or immune cells when IBD occurs, ligand-modified drug delivery systems targeting such receptors and cell adhesion molecules can specifically deliver drug into inflamed sites and obtain great curative effects. This review introduces the overexpressed receptors and cell adhesion molecules in inflamed colon sites and retrospects the drug delivery systems functionalized by related ligands. Finally, challenges and future directions in this field are presented to advance the development of the receptor-mediated targeted drug delivery systems for the therapy of IBD.

Oral delivery of proteins and peptides: Challenges, status quo and future perspectives

Proteins and peptides (PPs) have gradually become more attractive therapeutic molecules than small molecular drugs due to their high selectivity and efficacy, but fewer side effects. Owing to the poor stability and limited permeability through gastrointestinal (GI) tract and epithelia, the therapeutic PPs are usually administered by parenteral route. Given the big demand for oral administration in clinical use, a variety of researches focused on developing new technologies to overcome GI barriers of PPs, such as enteric coating, enzyme inhibitors, permeation enhancers, nanoparticles, as well as intestinal microdevices. Some new technologies have been developed under clinical trials and even on the market. This review summarizes the history, the physiological barriers and the overcoming approaches, current clinical and preclinical technologies, and future prospects of oral delivery of PPs.

An injectable micelle-hydrogel hybrid for localized and prolonged drug delivery in the management of renal fibrosis

Localized delivery, comparing to systemic drug administration, offers a unique alternative to enhance efficacy, lower dosage, and minimize systemic tissue toxicity by releasing therapeutics locally and specifically to the site of interests. Herein, a localized drug delivery platform ("plum‒pudding" structure) with controlled release and long-acting features is developed through an injectable hydrogel ("pudding") crosslinked

Bioresponsive micro-to-nano albumin-based systems for targeted drug delivery against complex fungal infections

As a typical human pathogenic fungus,

Evaluation of modified IAT with twoself-made low ionic-strength solutions / 中国输血杂志

【Objective】 To explore the clinical applications of low ionic strength salt solution polyethylene glycol (LISS-PEG) and low ionic strength salt solution bovine serum albumin (LISS-BSA) in the indirect antiglobulin test (IAT). 【Methods】 The common standard red blood cell(RBC) IgG irregular antibodies (anti-D, anti-M, anti-N, anti-S, anti-s, anti-Jka, anti-Jkb, anti-Fya, anti-Fyb, anti-Dia, anti-K) were reacted with RBCs with corresponding antigens in IAT with LISS-PEG and LISS-BSA modification for 5-minute and 10-minute incubations, and then compared the results with conventional IAT. One hundred of blood samples from patients presenting irregular antibodies of erythrocyte IgG were selected to observe the effect of these two self-made modification. The agglutination intensity was recorded by AABB scoring method. 【Results】 No difference was noticed in IAT intensity reaction between LISS-PEG 5-minute and 15-minute incubation (P>0.05), nor between 5-minute/15-minute LISS-BSA incubation and conventional IAT (P>0.05). However, LISS-PEG modification demonstrated a significant superiority over the conventional technique just after incubation with 5 minutes(P<0.05). 【Conclusion】 Using the self-made LISS-PEG as the enhancement medium allows not only reduced incubation time (5 minutes) but also increased intensity of the reaction, which shortens the cross-matching time for emergency blood transfusion and is worthy of popularization.

Influence of different protein supplements on the recovery and in vitro maturation of bovine oocytes / Influencia de diferentes suplementos proteicos en la recuperación y maduración in vitro de ovocitos bovinos / Influência de diferentes suplementações proteicas sobre a recuperação e maturação in vitro de oócitos bovinos

Abstract Background: Oocyte quality and maturation are influenced by protein supplementation. Objective: To evaluate the influence of fetal bovine serum (FBS) and bovine serum albumin (BSA) concentrations on the recovery and in vitro maturation (IVM) of bovine oocytes. Methods: The study was divided into Stage 1 (oocyte recovery), and Stage 2 (IVM). In the first stage, three experiments were conducted according to the recovery (R) medium used: (R1) 10 vs. 20% FBS; (R2) 5 vs. 10% BSA; and (R3) the best results from R1, R2, and the combination of FBS+BSA (5+5%). Within the second stage, the maturation medium was supplemented according to three experiments: (M1) 5 vs. 10% FBS; (M2) 0.4 vs. 0.8% BSA; and (M3) better results of M1, M2, and the combination of FBS+BSA (5+0.8%). Results: In Stage 1 (R1 and R2), the media with 10% FBS and 10% BSA showed better oocyte quality results and were defined for experiment R3. In R3, the 10% FBS and the combination of FBS+BSA (5+5%) allowed recovery of better-quality oocytes. In Stage 2 (M1 and M2), media with both levels of FBS (5 and 10%) and 0.8% BSA were defined as better according to the maturation and viability rates of cumulus cells, so they were defined for experiment M3. In M3, no difference was noted among the supplements. Conclusions: For oocyte recovery, 10% FBS and the combination of FBS+BSA (5+5%) can be used to obtain immature oocytes. For the in vitro maturation, FBS (both levels, 5 and 10%) and BSA (0.8%) can be used alone or in combination.

Resumen Antecedentes: La calidad y maduración de los ovocitos son influenciados por la suplementación proteica. Objetivo: Evaluar la influencia de concentraciones de suero fetal bovino (FBS) y albúmina sérica bovina (BSA) en la recuperación y maduración in vitro (IVM) de ovocitos bovinos. Métodos: El estudio se dividió en Etapa 1 (recuperación de ovocitos) y Etapa 2 (IVM). En la primera etapa, tres experimentos se realizaron de acuerdo con el medio de recuperación: (R1) 10 vs. 20% FBS; (R2) 5 vs. 10% BSA; y (R3) los mejores resultados de R1, R2 y la combinación de FBS+BSA (5+5%). En la segunda etapa, el medio de maduración fue suplementado para tres experimentos: (M1) 5 vs. 10% FBS; (M2) 0,4 vs. 0,8% BSA; y (M3) mejores resultados de M1, M2 y la combinación de FBS+BSA (5+0,8%). Resultados: En la Etapa 1 (R1 y R2), los medios con 10% FBS y 10% BSA mostraron mejores resultados de calidad oocitaria y fueron definidos para el experimento R3. En R3, 10% FBS y la combinación de FBS+BSA (5+5%) permitieron la recuperación de ovocitos de mejor calidad. En la Etapa 2 (M1 y M2), los medios con ambos niveles de FBS (5 y 10%) y 0,8% de BSA se definieron como mejores de acuerdo con las tasas de maduración y viabilidad de las células del cumulus, por lo que se definieron para el experimento M3. En M3, no se observó diferencia entre los suplementos. Conclusiones: Para la recuperación de ovocitos, se puede utilizar 10% de FBS y la combinación de FBS+BSA (5+5%) para obtener ovocitos inmaduros. Para la maduración in vitro, FBS (ambos niveles, 5 y 10%) y BSA (0,8%) se pueden usar solos o en combinación.

Resumo Antecedentes: A qualidade e a maturação de oócitos são influenciadas pela suplementação proteica. Objetivo: Avaliar a influência de concentrações de soro fetal bovino (FBS) e albumina sérica bovina (BSA) sobre a recuperação e maturação in vitro (IVM) de oócitos bovinos. Métodos: O estudo foi dividido em Etapa 1 (recuperação de oócitos) e Etapa 2 (IVM). Na primeira etapa, três experimentos foram realizados de acordo com o meio de recuperação: (R1) 10 vs. 20% FBS; (R2) 5 vs. 10% BSA; e (R3) melhores resultados de R1, R2 e a combinação de FBS+BSA (5+5%). Na segunda etapa, o meio de maturação foi suplementado de acordo com três experimentos: (M1) 5 vs. 10% FBS; (M2) 0,4 vs. 0,8% BSA; e (M3) melhores resultados de M1, M2 e a combinação de FBS+BSA (5+0,8%). Resultados: Na Etapa 1 (R1 e R2), os meios com 10% FBS e 10% BSA mostraram melhores resultados de qualidade oocitária e foram definidos para o experimento R3. Em R3, 10% FBS e a combinação de FBS+BSA (5+5%) permitiram a recuperação de oócitos de melhor qualidade. Na segunda etapa (M1 e M2), meios com ambos os níveis de FBS (5 e 10%) e 0,8% BSA foram definidos como os melhores de acordo com as taxas de maturação e viabilidade de células do cumulus, então foram definidos para o experimento M3. No M3, não houve diferença entre os suplementos. Conclusões: Para a recuperação oocitária, 10% FBS e a combinação de FBS+BSA (5+5%) podem ser usados para obter oócitos imaturos. Para maturação in vitro, FBS (ambos os níveis, 5 e 10%) e BSA (0,8%) podem ser usados sozinhos ou em combinação.

Evodiamine-inspired dual inhibitors of histone deacetylase 1 (HDAC1) and topoisomerase 2 (TOP2) with potent antitumor activity

A great challenge in multi-targeting drug discovery is to identify drug-like lead compounds with therapeutic advantages over single target inhibitors and drug combinations. Inspired by our previous efforts in designing antitumor evodiamine derivatives, herein selective histone deacetylase 1 (HDAC1) and topoisomerase 2 (TOP2) dual inhibitors were successfully identified, which showed potent and antitumor potency. Particularly, compound was orally active and possessed excellent antitumor activity in the HCT116 xenograft model (TGI = 75.2%, 150 mg/kg, .) without significant toxicity, which was more potent than HDAC inhibitor vorinostat, TOP inhibitor evodiamine and their combination. Taken together, this study highlights the therapeutic advantages of evodiamine-based HDAC1/TOP2 dual inhibitors and provides valuable leads for the development of novel multi-targeting antitumor agents.

Biophysical interactions between silver nanoparticle-albumin interface and curcumin / 药物分析学报

Active targeted drug delivery methods facilitate effective uptake of functionalized nanoparticles through receptor-mediated transcytosis. In recent years, albumin-nanoparticle interaction has been critically examined so that this functionalized nanoparticle can be efficiently loaded with drugs. The present investigation aims at understanding the adsorption of Bovine Serum Albumin (BSA) on Silver Nano-particle (SNP) surface, preparation of soft conjugates (SC) and hard conjugates (HC) of BSA-functionalized SNP (SNP-BSA), and their interaction with curcumin (CUR). HC contains tightly bound BSA whereas SC involves tightly and loosely bound BSA. Increase in the hydrodynamic radii of conjugates was observed upon SNP incubation with increased concentration of BSA. Three different SNP-BSA conjugate ratios were selected to study their interaction with CUR. Fluorescence spectroscopy showed a strong association between CUR and SNP:BSA conjugates. However, binding varied with a change in the conjugate ratio. Circular Dichroism (CD)/Fourier Transform Infrared (FTIR) spectroscopy revealed the alterations in the secondary structure of BSA upon CUR binding to the conjugates. Zeta potential data indicated stable conjugate formation. CUR in SNP:BSA conjugate was found to have a higher half-life as compared to the control. We believe that this is the first biophysical characterization report of conjugates that can be effectively extrapolated for targeted drug delivery.

Preparation and in vitro release profiling of PLGA microspheres containing BSA as a model protein

Conventional drug formulations are incapable of adequate delivery of proteins and peptides for therapeutic purposes. As these molecules have very short biological half-life, multiple dosing is required to achieve the desirable therapeutic effects. Microspheres are able to encapsulate proteins and peptide in the polymeric matrix while protecting them from enzymatic degradation. In this study Bovine Serum Albumin (BSA) matrix type microspheres were fabricated using Polylactide-co-glycolide (PLGA) by double emulsion solvent evaporation method. The effects of variables such as homogenizer speed, molecular weight of polymer and the effect of pH of the water phases, were investigated against factors such as drug loading, encapsulation efficiency, morphology, size, drug distribution and release profile of the microspheres. Results, suggested that an increase in homogenization speed leads to a decrease in microsphere size. The increase in homogenization speed also caused a significant effect on the release profile only when higher molecular weight of polymer had been used.. The pH change of the internal aqueous phase led to modification of surface morphology of spheres to a porous structure that significantly increased the total amount of released protein. Integrity of protein structure was intact as shown by SDS-PAGE. According to the results, it can be concluded that we achieved a reproducible method regarding controlled protein delivery for different sizes of particles.

Bovine serum albumin-based nanoparticles containing the flavonoid rutin produced by nano spray drying

Rutin is a flavonoid compound obtained from different vegetables and fruits; specifically, it is found in the seeds of buckwheat and in fruit peels, particularly citrus. It is also an important constituent of red wine. Rutin exhibits various biological properties including antiviral, vasoprotective, anti-inflammatory, and anticarcinogenic activities. However, its antioxidant activity is the most well studied. Despite the potential for in vitro applications, rutin presents low oral bioavailability that affects its biological activities. Nanoparticles composed of polymers, protein, or lipids are of great importance in the pharmaceutical and nutraceutical areas due to their physicochemical properties, which improve the pharmacokinetics of the drug which is loaded within. This study presents the production of bovine serum albumin (BSA) nanoparticles containing rutin by nano spray drying. Nanoparticles were characterized in terms of mean particle size, size distribution, morphology, zeta potential, and drug content; as well as their antioxidant activity. The optimized spray-drying conditions produced spherical particles with a mean size of 316 nm, zeta potential of −32 mV, and encapsulation efficiency around 32%. Moreover, when antioxidant activity toward the ABTS+ radical was assayed, nanoencapsulation increased the IC50 of rutin by 2-fold. The nano spray-drying process proved to be suitable for the production of rutin-loaded BSA nanoparticles with potential antioxidant activity.

Interaction Between Lobetyolin and Bovine Serum Albumin by Steady-State Fluorescence and Molecular Docking / 中国实验方剂学杂志

Objective:The interaction between lobetyolin and bovine serumal bumin（bovine serum albumin，BSA）. Method:By the steady-state fluorescence analysis method，the molecular-docking，ultraviolet absorption spectrum and fluorescence quenching were used to calculate quenching constant and binding constant，the number of sites，the position，the force and the distance of lobetyolin-BSA system. In addition， the effect of metalionson quenching constant of the lobetyolin-BSA system was studied. Result:The quenching constant was 1.25×104 L·mol-1（37 ℃），the binding constant was 2.95×104 L·mol-1（37 ℃），and the number of sites was 1 and bound with site 1 in ⅡA of BSA， thermodynamic meters were ΔH=-19.374 kJ·mol-1，ΔS=23.1 J·mol-1·K-1， the interaction distance was 3.2 nm. Meta lions could accelerate the quenching. Conclusion:By the steady-state fluorescence technique，molecular-docking and ultraviolet absorption spectrum，the quenching mechanism of Lobetyolin-BSA is quiescent quenching，and the interactive force is electro static force. The Lobetyolin-BSA can be well combined. At the same time，it also shows that the molecular docking results are similar to the experimental results obtained by steady-state fluorescence analysis.

Adapting liposomes for oral drug delivery

Liposomes mimic natural cell membranes and have long been investigated as drug carriers due to excellent entrapment capacity, biocompatibility and safety. Despite the success of parenteral liposomes, oral delivery of liposomes is impeded by various barriers such as instability in the gastrointestinal tract, difficulties in crossing biomembranes, and mass production problems. By modulating the compositions of the lipid bilayers and adding polymers or ligands, both the stability and permeability of liposomes can be greatly improved for oral drug delivery. This review provides an overview of the challenges and current approaches toward the oral delivery of liposomes.

Novel ractopamine–protein carrier conjugation and its application to the lateral flow strip test for ractopamine detection in animal feed / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

In this work, a novel conjugate of ractopamine and bovine serum albumin (RAC–BSA) has been developed via the Mannich reaction, with a mole coupling ratio for RAC–BSA of 9:1. The proposed conjugation method provides a simple and one-step method with the use of fewer reagents compared with other conjugation methods for competitive immunoassays. RAC–BSA conjugation was used to fabricate a competitive lateral flow strip test for RAC detection in animal feed. For sample preparation, RAC was spiked in swine feed purchased from the local markets in Thailand, and methanol and running buffer at a volume ratio of 10:90 was used as extraction buffer. The procedures for sample preparation were completed within 25 min. Under optimal conditions, the limit of detection (LOD), assessed by the naked eye within 5 min, was found to be 1 ng/g. A semi-quantitative analysis was also conducted using a smart phone and computer software, with a linearity of 0.075–0.750 ng/g, calculated LOD of 0.10 ng/g, calculated limit of quantitation of 0.33 ng/g, and good correlation of 0.992. The recoveries were found in the range of 96.4%–103.7% with a relative standard deviation of 2.5%–3.6% for intra- and inter-assays. Comparison of the results obtained by the strip test with those obtained by enzyme-linked immunosorbent assay had a good agreement in terms of accuracy. Furthermore, this strip test exhibited highly specific RAC detection without cross reactivity with related compounds. Therefore, the RAC–BSA conjugation via the Mannich reaction can be accepted as a one-step and easy conjugation method and applied to the competitive lateral flow strip test.

Study on interaction between ginsenosides Rg_1,Rb_1 and Ro and bovine serum albumin / 中国中药杂志

Small molecules with physiological or pharmacological activities need to interact with biological macromolecules in order to function in the body. As the protein with the highest proportion of plasma protein,serum albumin is the main protein binding to various endogenous or exogenous small molecules. Serum albumin interacts with small molecules in a reversible non-covalent manner and transports small molecules to target sites. Bovine serum albumin( BSA) is an ideal target protein for drug research because of its low cost and high homology with human serum albumin. The research on the interaction between drugs and BSA has become a hotspot in the fields of pharmacy,medicine,biology and chemistry. In this research,molecular docking method was used to study the interaction between three small ginsenosides with high pharmacological value( Rg_1,Rb_1,Ro) and bovine serum albumin( BSA),and the binding mode information of three ginsenosides interacting with BSA was obtained. The results of molecular docking showed that ginsenosides and amino acid residues in the active pocket of proteins could be combined by hydrophobic action,hydrogen bonding and electrostatic action. The interaction between small ginsenosides and bovine serum albumin is not the only form,and their interaction has many forms of force. The interaction between these molecules and various weak forces is the key factor for the stability of the complex. The results of this study can provide the structural information of computer simulation for the determination of the interaction patterns between active components and proteins of ginseng.

Binding interaction of harpagoside and bovine serum albumin: spectroscopic methodologies and molecular docking / 中国中药杂志

Scrophularia ningpoensis has exhibited a variety of biological activities and been used as a pharmaceutical product for the treatment of inflammatory ailment, rheumatoid arthritis, osteoarthritis and so on. Harpagoside (HAR) is considerer as a main bioactive compound in this plant. Serum albumin has important physiological roles in transportation, distribution and metabolism of many endogenous and exogenous substances in body. It is of great significance to study the interaction mechanism between HAR and bovine serum albumin (BSA). The mechanism of interaction between HAR and BSA was investigated using 2D and 3D fluorescence, synchronous florescence, ultraviolet spectroscopy and molecular docking. According to the analysis of fluorescence spectra, HAR could strongly quench the fluorescence of BSA, and the static quenching process indicated that the decrease in the quenching constant was observed with the increase in temperature. The magnitude of binding constants (KA) was more than 1×10⁵ L·mol⁻¹, and the number of binding sites(n) was approximate to 1. The thermodynamic parameters were calculated through analysis of fluorescence data with Stern-Volmer and Van't Hoff equation. The calculated enthalpy change (ΔH) and entropy change (ΔS) implied that the main interaction forces of HAR with BSA were the bonding interaction between van der Waals forces and hydrogen. The negative values of energy (ΔG) demonstrated that the binding of HAR with BSA was a spontaneous and exothermic process. The binding distance(r) between HAR and BSA was calculated to be about 2.80 nm based on the theory of Frster's non-radiation energy transfer, which indicated that energy is likely to be transfer from BSA to HAR. Both synchronous and 3D florescence spectroscopy clearly revealed that the microenvironment and conformation of BSA changed during the binding interaction between HAR and BSA. The molecular docking analysis revealed HAR is more inclined to BSA and human serum albumin (HSA) in subdomain ⅡA (Sudlow's site I). This study will provide valuable information for understanding the action mechanism of HAR.

Preparation of PLGA wrinkled microparticles for bovine serum albumin immobilization / 国际生物医学工程杂志

Objective To develop a method for the synthesis of poly [lactic-co-(glycolic acid)] (PLGA) wrinkled microparticles,and to investigate their immobilization on model protein,i.e.bovine serum albumin (BSA),so as to provide a scientific basis for the preparation of artificial antigen-presenting cells (aAPCs).PLGA wrinkled microparticles were prepared by double emulsion-solvent evaporation method combined with porogen NH4HCO3.The effects of PLGA relative molecular mass,porogen mass concentration and double emulsion stirring speed on the morphology of PLGA micro particles were investigated.The PLGA wrinkled particles were incubated with different concentrations of FITC-conjugated BSA (FITC-BSA).The levels of BGA loaded with PLGA wrinkled particles were detected by laser scanning confocal microscopy,flow cytometry and diquinoline formic acid.The effect of the loading process on the BSA structure was analyzed by circular dichroism spectrometer.Results The molecular weight of 5 000 was the optimized parameters for PLGA wrinkled microparticles preparation.The morphology of PLGA wrinkled particles could be maintained when the mass concentration of porogen NH4HCO3 was less than 10 g/L.When the mixing speed of multiple emulsion increased from 400 r/min to 3 600 r/min,the average particle size of PLGA wrinkled particles decreased from 35 μm to 9 μm,which meets the size requirement of artificial aAPCs.The fluorescence intensity of PLGA wrinkled particles was directly proportional to the concentration of BSA,and the BSA structure was not affected by the adsorption of BSA by the PLGA wrinkled particles.Conclusion The relative molecular mass of PLGA has an important influence on the morphology of the particles.PLGA with a relative molecular mass of 5 000 can be used to prepare particles with a wrinkled topology,which can load proteinaceous macromolecules and maintain protein activity.This result has potential applications in artificial aAPCs.