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1.
Biosens Bioelectron ; 151: 111966, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31999576

RESUMO

Known for their capabilities in automated fluid manipulation, microfluidic devices integrated with pneumatic valves are broadly used for researches in life science and clinical practice. The application is, however, hindered by the high cost and overly complex fabrication procedure. Here, we present an approach for fabricating molds of active fluidic devices using a benchtop 3D printer and a simple 2-step protocol (i.e. 3D printing and polishing). The entire workflow can be completed within 6 h, costing less than US$ 5 to produce all necessary templates for PDMS replica molding, which have smooth surface and round-shaped pneumatic valve structures. Moreover, 3D printing can create unique bespoke on-off objects of a wide range of dimensions. The millimeter- and centimeter-sized features allow examination of large-scale biological samples. Our results demonstrate that the 3D-printed active fluidic device has valve control capacities on par with those made by photolithography. Controlled nutrients and ligands delivery by on-off active valves allows generation of dynamic signals mimicking the ever-changing environmental stimuli, and combinatorial/sequential drug inputs for therapeutic screening on liver tumor spheroid. We believe that the proposed methodology can pave the way for integration of active fluidic systems in research labs, clinical settings and even household appliances for a broad range of application.

2.
Bioorg Med Chem ; 27(10): 2112-2121, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30981607

RESUMO

A series of bi-functional 7-hydroxycoumarin platinum(IV) complexes were synthesized, characterized, and evaluated for antitumor activities. The 7-hydroxycoumarin platinum(IV) complexes display moderate to effective antitumor activities toward the tested cell lines and show much potential in overcoming drug resistance of platinum(II) drugs. In reducing microenvironment, the title compounds could be reduced to platinum(II) complex accompanied with two equivalents of coumarin units. By a unique mechanism, the 7-hydroxycoumarin platinum(IV) complex attacks DNA via the released platinum(II) compound, meanwhile it also inhibits the activities of cyclooxygenase by coumarin fragment. This action mechanism might be of much benefit for reducing tumor-related inflammation in the progress of inhibiting tumor proliferation and overcoming cisplatin resistance. The incorporation of 7-hydroxycoumarin leads to significantly enhanced platinum accumulation in both whole tumor cells and DNA. The HSA interaction investigation reveals that the tested coumarin platinum(IV) compound could effectively combine with HSA via van der Waals force and hydrogen bond.

3.
J Inorg Biochem ; 194: 34-43, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30826588

RESUMO

A series of new 4-hydroxycoumarin platinum(IV) complexes were designed, synthesized and evaluated as antitumor agents. All the title compounds display moderate to effective antitumor activities toward the tested cell lines and two prominent compounds were screened out with activities comparable to cisplatin and oxaliplatin. The mechanism investigation demonstrates that the platinum(IV) compounds could be reduced to bivalence and exert significant genotoxicity to tumor cells. Meanwhile the coumarin moiety endows the title compounds with cyclooxygenase inhibitory competence which might favour the reduction of tumor-related inflammation and further influence tumor proliferation. The coumarin platinum(IV) complex could effectively induce apoptosis of SKOV-3 cells through up-regulating the expression of caspase3 and caspase9. Furthermore, the conversion of platinum(II) drugs to platinum(IV) form via the conjunction with 4-hydroxycoumarin enhances the drug uptake in whole cells and DNA simultaneously. Moreover, the 4-hydroxycoumarin platinum(IV) complex could combine with human serum albumin via van der Waals force and hydrogen bond, which would influence their transport and bioactivities in vivo.

4.
Eur J Pharm Sci ; 124: 127-136, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30153524

RESUMO

Naphthalimide platinum(IV) antitumor complexes with potential dual DNA damage mechanism were designed, synthesized and evaluated for antitumor activities. The incorporation of DNA targeted naphthalimide group to the platinum(IV) system exerts much positive impacts on their antitumor efficacy. The mechanism research reveals that the title compounds could interact with dsDNA in platinum(IV) form via the naphthalimide group and cause DNA lesion. The further reduction would release platinum(II) complexes and naphthalimide acids which would induce remarkable secondary damage to DNA. Furthermore, the naphthalimide platinum(IV) compounds could combine with human serum albumin via electrostatic force, which are favourable for their storage and transport in blood. Moreover, the title compounds exhibit higher accumulation in tumor cells, and exert lower toxic and higher safe properties than oxaliplatin in vivo.


Assuntos
Antineoplásicos/farmacologia , Naftalimidas/farmacologia , Compostos Organoplatínicos/farmacologia , Linhagem Celular Tumoral , Dano ao DNA , Humanos
5.
Int J Nanomedicine ; 12: 6909-6921, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29075110

RESUMO

PURPOSE: Breast cancer stem cells (CSCs) are responsible for the initiation, recurrence, and metastasis of breast cancer. Sufficient evidence has established that breast cancer cells can spontaneously turn into breast CSCs. Thus, it is essential to simultaneously target breast CSCs and cancer cells to maximize the efficacy of breast cancer therapy. HER2 has been found to be overexpressed in both breast CSCs and cancer cells. We developed salinomycin-loaded polymer-lipid hybrid anti-HER2 nanoparticles (Sali-NP-HER2) to target both HER2-positive breast CSCs and cancer cells. METHODS: The antitumor activity of Sali-NP-HER2 constructed by conjugating anti-HER2 antibodies to polymer-lipid salinomycin nanoparticles was evaluated in vitro and in vivo. RESULTS: Sali-NP-HER2 efficiently bound to HER2-positive breast CSCs and cancer cells, resulting in enhanced cytotoxic effects compared with non-targeted nanoparticles or salinomycin. In mice bearing breast cancer xenografts, administration of Sali-NP-HER2 exhibited superior efficacy in inhibiting tumor growth. Sali-NP-HER2 reduced the breast tumorsphere formation rate and the proportion of breast CSCs more effectively than non-targeted nanoparticles or salinomycin alone. CONCLUSION: Sali-NP-HER2 represents a promising approach in treating HER2-positive breast cancer by targeting both breast CSCs and cancer cells.


Assuntos
Neoplasias da Mama/tratamento farmacológico , Sistemas de Liberação de Medicamentos/métodos , Nanopartículas/administração & dosagem , Piranos/administração & dosagem , Receptor ErbB-2/metabolismo , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/farmacologia , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Feminino , Humanos , Lipídeos/química , Camundongos , Nanopartículas/química , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/patologia , Polímeros/química , Receptor ErbB-2/antagonistas & inibidores , Receptor ErbB-2/imunologia , Ensaios Antitumorais Modelo de Xenoenxerto
6.
Spectrochim Acta A Mol Biomol Spectrosc ; 173: 584-592, 2017 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-27776313

RESUMO

Combination therapy with more than one therapeutic agent can improve therapeutic efficiency and decrease drug resistance. In this study, the interactions of human serum albumin (HSA) with individual or combined anticancer drugs, (-)-epigallocatechin-3-gallate (EGCG) and 5-fluorouracil (FU), were investigated by fluorescence and circular dichroism (CD) spectroscopy. The results demonstrated that the interaction of EGCG or FU with HSA is a process of static quenching and EGCG formed a more stable complex. The competitive experiments of site markers suggested that both anti-carcinogens mainly bound to site I (subdomain IIA). The interaction forces which play important roles in the binding process were discussed based on enthalpy and entropy changes. Moreover, the competition binding model for a ternary system was proposed so as to precisely calculate the binding parameters. The results demonstrated that one drug decreased the binding affinity of another drug with HSA, resulting in the increasing free drug concentration at the action sites. CD studies indicated that there was an alteration in HSA secondary structure due to the binding of EGCG and FU. It can be concluded that the combination of EGCG with FU may enhance anticancer efficacy. This finding may provide a theoretical basis for clinical treatments.


Assuntos
Catequina/análogos & derivados , Fluoruracila/metabolismo , Albumina Sérica Humana/química , Albumina Sérica Humana/metabolismo , Antimetabólitos Antineoplásicos/metabolismo , Antineoplásicos Fitogênicos/metabolismo , Sítios de Ligação , Ligação Competitiva , Catequina/metabolismo , Dicroísmo Circular , Sinergismo Farmacológico , Humanos , Ibuprofeno/metabolismo , Estrutura Secundária de Proteína , Espectrometria de Fluorescência , Termodinâmica , Varfarina/metabolismo
7.
Nanoscale Res Lett ; 11(1): 126, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26951126

RESUMO

In this report, a novel photocatalyst based on Bi2WO6/Ag2S heterostructures was prepared by a 3-mercaptopropionic acid (MPA)-assisted route at room temperature. Compared to bare Bi2WO6 and Ag2S nanoparticles, the as-formed Bi2WO6/Ag2S heterostructures exhibit enhanced photocatalytic activity for the degradation of rhodamine B (Rh B) under visible-light irradiation. This kind of enhancement in the photocatalytic activity is considered to be the synergistic effects of both the effective electron-hole separation and expansion of the light-absorption range. The pH of the solution is of vital importance to the photocatalytic activity of the as-formed Bi2WO6/Ag2S heterostructures. Under low pH value, the photosensitization process is suppressed, while under higher pH value, the photosensitization process is favored. The mechanism of the photocatalytic process was proposed by the active-species-trapping experiments, indicating that the photogenerated holes (h(+)) play a crucial role in the degradation of Rh B under visible light. The enhanced photocatalytic performance of this heterostructure makes it a promising material for the treatment of dye-containing wastewater.

8.
Food Chem ; 196: 148-54, 2016 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-26593476

RESUMO

The stability and bioavailability of catechins, a kind of tea polyphenols with health benefit, could be improved by complexing with cyclodextrins. The aim of this study was to investigate the complexation of two geometrical isomers, (+)-catechin and (-)-epicatechin, with hydroxypropyl-ß-cyclodextrin (HP-ß-CD) in tris-HCl buffer solutions at pH 6.8-8.0 using isothermal titration calorimetry, fluorescence and proton nuclear magnetic resonance spectroscopy. Experimental results showed that these inclusion interactions are primarily enthalpy-driven processes. The complexation constant (KC) of EC+HP-ß-CD complex was less than that of CA+HP-ß-CD at the same temperature and pH value. Temperature and pH studies showed that the KC value decreased with the rise of temperature and pH. Stability study indicated that HP-ß-CD showed a stronger protection effect on CA than that on EC. The different inclusion modes between CA and EC were discussed in terms of the discrepancy in their molecular structures.


Assuntos
Catequina/química , Espectrometria de Fluorescência/métodos , beta-Ciclodextrinas/química , 2-Hidroxipropil-beta-Ciclodextrina , Estrutura Molecular , Temperatura Ambiente
9.
Artigo em Chinês | MEDLINE | ID: mdl-26281063

RESUMO

OBJECTIVE: To assess and compare the two procedures, total thyroidectomy (TT) and partial thyroidectomy (PT), for papillary thyroid cancer in terms of associated injuries, postoperative complication, recurrence rate and survival, so as to provide a reference and basis for surgical procedure option of this disease. METHOD: Strictly specified into the exclusion criteria, the combination of computer retrieval and manual retrieval and retrieval systems such as CNKI, Wang Fan, PubMed, central, CBM database. Total thyroidectomy and partial thyroidectomy for the treatment of patients with thyroid papillary cancer related literature were compared, with the retrieval time until December 31, 2013. RESULT: According to the retrieval strategy 4630 literatures were found, and 20 witch matched the exclusion criteria were left, all were retrospective study. TT and PT group of recurrent laryngeal nerve injury rate are 5.9%, 2.0% respectively [OR = 0.39, 95% CI (0.17 - 0.90), P < 0.05], TT and PT group of parathyroid injury rate are respectively 4.9%, 0.8% respectively [OR = 0.23, 95% CI (0.08 - 0.68), P < 0.01]. The TT group of 10 years survival rate is 95.24% - 100%, and the PT group is 96.8% - 99.2% [OR = 0.03, 95% CI (0 - 0.34), P < 0.01]. Unstaged, unstaged TT group' postoperative recurrence rate is 4.7%, while PT group is 12.6% [OR = 3.21, 95% CI (1.57 - 6.57), P < 0. 01]. Postoperative recurrence of stage I TT group and PT group are 4.9%, 7.8% respectively [OR = 3.82, 95% CI (1. 07-13.66) P < 0.05]; The rate of stage II TT group is 0.5%, while the rate of PT group is 15.9% [OR = 17.23, 95% CI (4.03 - 73.73), P < 0.01]. CONCLUSION: Different methods of primary thyroid papillary carcinoma surgical treatment can all obtaina good survival, but the rate of laryngeal recurrent nerve injury and parathyroid injury caused by partal throidectomy is relatively lower. As a result, partial thyroidectomy can be a good choice for early stage thyroid papillary carcinoma.


Assuntos
Carcinoma/cirurgia , Neoplasias da Glândula Tireoide/cirurgia , Tireoidectomia/métodos , Carcinoma Papilar , Humanos , Recidiva Local de Neoplasia , Glândulas Paratireoides , Complicações Pós-Operatórias , Traumatismos do Nervo Laríngeo Recorrente , Estudos Retrospectivos , Taxa de Sobrevida , Câncer Papilífero da Tireoide
10.
Food Chem ; 168: 270-5, 2015 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-25172710

RESUMO

The inclusion complex of 7-hydroxy-4-methylcoumarin (7H4MC) with sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD) was investigated by means of UV-vis, circular dichroism and (1)H NMR spectroscopy in phosphate buffer solutions at different temperatures and pH values. The stoichiometric ratio of the complexation was found to be 1:1 and the stability constants (KC) were estimated from phase solubility analysis. The thermodynamic parameters of standard Gibbs free energy change, ΔG(o), enthalpy change, ΔH(o), and entropy change, ΔS(o), for the complexation process were obtained by using the van't Hoff equation and Gibbs-Helmholtz equation. The large negative ΔH(o) and the small negative or positive ΔS(o) (|ΔH(o)|>|TΔS(o)|) demonstrated that the inclusion interaction was an enthalpy-driven process. The positive signal of circular dichroism indicated that 7H4MC penetrated the cavity in such a way that the transition moment of the guest chromophore was parallel to the long axis of SBE-ß-CD cavity. Moreover, the (1)H NMR spectrum showed that the entire 7H4MC molecule, except the hydroxyl group, was included in the SBE-ß-CD cavity.


Assuntos
Himecromona/química , beta-Ciclodextrinas/química , Estabilidade de Medicamentos , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Solubilidade , Temperatura Ambiente , Termodinâmica
11.
Artigo em Chinês | MEDLINE | ID: mdl-25223066

RESUMO

The prevalence of Echinococcus granulosus infection in dogs and livestock was investigated in Xinjiang Production and Construction Corps by stratified random sampling. A total of 5 391 dog feces were detected by double antibody sandwich ELISA, and the positive rate of dog coproantigen was 0.69% (37/5 391). The livestock were subjected to necropsy, inspection and palpation. The prevalence of E. granulosus infection in livestock was 3.88% (431/11 122).


Assuntos
Doenças do Cão/epidemiologia , Equinococose/veterinária , Echinococcus granulosus , Gado/parasitologia , Animais , Anticorpos , Antígenos de Helmintos , Cães , Equinococose/epidemiologia , Ensaio de Imunoadsorção Enzimática , Fezes , Prevalência
12.
Anal Bioanal Chem ; 406(4): 1163-72, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24026515

RESUMO

A synthetic redox probe structurally related to natural pyridoacridones was designed and electrochemically characterised. These heterocycles behave as DNA intercalators due to their extended planar structure that promotes stacking in between nucleic acid base pairs. Electrochemical characterization by cyclic voltammetry revealed a quasi-reversible electrochemical behaviour occurring at a mild negative potential in aqueous solution. The study of the mechanism showed that the iminoquinone redox moiety acts similarly to quinone involving a two-electron reduction coupled with proton transfer. The easily accessible potential region with respect to aqueous electro-inactive window makes the pyridoacridone ring suitable for the indirect electrochemical detection of chemically unlabelled DNA. Its usefulness as electrochemical hybridization indicator was assessed on immobilised DNA and compared to doxorubicin. The voltamperometric response of the intercalator acts as an indicator of the presence of double-stranded DNA at the electrode surface and allows the selective transduction of immobilised oligonucleotide hybridization at both macro- and microscale electrodes.


Assuntos
Acridinas/química , Técnicas Biossensoriais/métodos , DNA/química , Substâncias Intercalantes/química , Fenantrolinas/química , Técnicas Biossensoriais/instrumentação , DNA/genética , Eletroquímica , Eletrodos , Hibridização de Ácido Nucleico
13.
J Agric Food Chem ; 62(1): 244-50, 2014 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-24308546

RESUMO

The utilization of kaempferol and its glycosides in food and pharmaceutical industries could be improved by the formation of inclusion complexes with cyclodextrins at different pH. This study explores the complexation of kaempferol-4'-glucoside with sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD), hydroxypropyl-ß-cyclodextrin (HP-ß-CD), and methylated-ß-cyclodextrin (M-ß-CD) in phosphate buffer solutions of different pH using isothermal titration calorimetry, UV-vis absorption and proton nuclear magnetic resonance spectroscopy at 298.2 K. Experimental results showed that kaempferol-4'-glucoside binds with the three ß- cyclodextrins in the same 1:1 stoichiometry. The rank order of stability constants is SBE-ß-CD > HP-ß-CD > M-ß-CD at the same pH level and pH 6.0 > pH 7.4 > pH 9.0 for the same cyclodextrin. The binding of kaempferol-4'-glucoside with the three ß-cyclodextrin derivatives is synergistically driven by enthalpy and entropy at pH 6.0 and enthalpy-driven at pH 7.4 and 9.0. The possible inclusion mode was that in the cavity of ß-CD is included the planar benzopyranic-4-one part of the kaempferol-4'-glucoside.


Assuntos
Glucosídeos/química , Quempferóis/química , beta-Ciclodextrinas/química , Calorimetria , Entropia , Concentração de Íons de Hidrogênio , Estrutura Molecular , Solubilidade , Análise Espectral
14.
Artigo em Inglês | MEDLINE | ID: mdl-23892509

RESUMO

Properties of the inclusion complexes of quercetin (QUE) with sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD), hydroxypropyl-ß-cyclodextrin (HP-ß-CD), and methylated-ß-cyclodextrin (M-ß-CD) in tris-HCl buffer solutions of pH 7.40 were investigated. The stoichiometry and thermodynamic parameters for the complexation process (stability constants K, Gibbs free energy change ΔG, enthalpy change ΔH and entropy change ΔS) were determined using phase-solubility and fluorescence spectra analysis. The thermodynamic studies indicated that the inclusion reactions between QUE and the three ß-CDs are enthalpy-driven processes. Proton nuclear magnetic resonance spectroscopy indicated that B-ring, C-ring, and part of A-ring of QUE interact with the cavity of ß-CDs. The antioxidant activity of QUE and its inclusion complexes were determined by the scavenging of stable radical DPPH(*). The results showed that the complexed QUE/CDs were more effective than free QUE, with the QUE/SBE-ß-CD complex as the best form.


Assuntos
Antioxidantes/química , Quercetina/química , beta-Ciclodextrinas/química , Óxido de Deutério/química , Dimetil Sulfóxido/química , Concentração de Íons de Hidrogênio , Cinética , Espectroscopia de Ressonância Magnética , Dinâmica não Linear , Prótons , Solubilidade , Soluções , Espectrometria de Fluorescência , Termodinâmica
15.
Virology ; 420(2): 156-63, 2011 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-21968197

RESUMO

The Jun NH2-terminal kinase (JNK) which serves as an important component of cellular signal transduction pathways has been shown to regulate many viral infections. The present study demonstrated for the first time that infectious bursal disease virus (IBDV), the causative agent of a highly contagious disease in chickens, can activate JNK1/2 pathway in IBDV-infected cells dependent upon viral replication. IBDV-induced JNK1/2 activation causes its downstream target c-Jun phosphorylation, which kinetically paralleled JNK1/2 activation. Investigations into the mechanism of JNK1/2 regulation revealed that inhibition of JNK1/2 activation leads to reduced viral progeny release, which is associated with decreased viral transcription and lower virus protein expression, and thereby limiting apoptotic cell death as evidenced by blockage of Bax activation, cytochrome c release, and caspase activation. These data suggest that the JNK pathway plays an important role in the IBDV replication and contributes to virus-mediated changes in host cells.


Assuntos
Apoptose , Vírus da Doença Infecciosa da Bursa/fisiologia , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Sistema de Sinalização das MAP Quinases , Replicação Viral , Animais , Caspase 3/metabolismo , Caspase 9/metabolismo , Linhagem Celular , Embrião de Galinha , Galinhas , Citocromos c/metabolismo , Ativação Enzimática , Proteínas Quinases JNK Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases JNK Ativadas por Mitógeno/genética , Fosforilação , Estaurosporina/farmacologia , Proteínas Virais/genética , Proteínas Virais/metabolismo , Proteína X Associada a bcl-2/metabolismo
16.
J Pharm Sci ; 100(7): 2945-51, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21328584

RESUMO

As density (free volume) of the amorphous solids should be related to mobility and stability, an attempt was made to develop a simple, sensitive, and reproducible method to evaluate free volume via high-precision gas pycnometry density measurements, and to apply this methodology to study the variation of free volume with formulation and thermal history (i.e., annealing). Annealed samples were prepared either by heating the product after freeze drying (postannealing) or drying at higher temperature in secondary drying than normal (in-process annealing). Density was measured using a gas pycnometer. We find that the key to high-precision density measurements is isolation of the instrument from atmospheric moisture; accordingly, all operations were carried out in a dry box. With suitable care, densities of amorphous freeze-dried products can be measured with a precision of better than 0.5% in a series of independent but nominally identical samples. Density decreased with increasing molecular weight of dextran, but density of proteins was independent of molecular weight. Small but significant increases in density upon annealing were observed for several formulations. Thus, we conclude that accurate density measurements may be made by carefully controlling residual moisture. Density may be a useful parameter to predict long-term stability.


Assuntos
Densitometria , Liofilização , Gases , Proteínas/química , Tecnologia Farmacêutica/métodos , Molhabilidade , Química Farmacêutica , Dessecação , Dextranos/química , Estabilidade de Medicamentos , Temperatura Alta , Hormônio do Crescimento Humano/química , Imunoglobulina G/química , Modelos Químicos , Peso Molecular , Pós , Pressão , Estabilidade Proteica , Reprodutibilidade dos Testes , Soroalbumina Bovina/química , Água/química , beta-Galactosidase/química
17.
J Pharm Sci ; 99(2): 663-82, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19798753

RESUMO

The objective of this study was to investigate the impact of heat treatment (annealing) on the molecular mobility and chemical stability of dried sodium ethacrynate (ECA). ECA was lyophilized with sucrose or trehalose, and some samples were held as control while others were annealed at temperatures below T(g). Enthalpy recovery was studied with DSC and free volume was estimated based on density measurements. Global mobility was measured by the thermal activity monitor (TAM), and fast local mobility was studied with neutron backscattering. Formation of ECA dimer was measured by reverse phase HPLC. Maximum enthalpy recovery and minimum fictive temperature were observed at about T(g)-15 degrees C for both ECA/saccharide formulations. Annealing ECA in amorphous solids improved chemical stability, as shown by the decrease in degradation rate constant relative to the control. Annealed samples exhibited larger structural relaxation time than the control, and thus annealing decreased global mobility in the system. However, annealing does not significantly impact the local mobility. Chemical stability correlates with structural relaxation time, fictive temperature, and free volume, which suggests that improved stability is mainly a result of the reduced global mobility upon annealing.


Assuntos
Ácido Etacrínico/química , Varredura Diferencial de Calorimetria , Cromatografia Líquida de Alta Pressão , Cristalização , Dimerização , Estabilidade de Medicamentos , Excipientes , Liofilização , Temperatura Alta , Umidade , Conformação Molecular , Nêutrons , Proteínas/química , Espalhamento de Radiação , Sacarose/química , Temperatura Ambiente , Termodinâmica , Trealose/química
18.
J Pharm Sci ; 99(2): 683-700, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19798764

RESUMO

The objective of this research was to investigate the impact of thermal treatment on storage stability of an IgG1 fusion protein. IgG1 protein formulations were prepared by freeze-drying the protein with sucrose. Some samples were used as controls, and others were subjected to a further heat treatment (annealing). The protein structure was investigated with Fourier transform infrared spectroscopy (FTIR), and protein aggregation was monitored with size exclusion HPLC. Enthalpy recovery was studied using DSC, and global mobility represented by the structural relaxation time constant (tau(beta)) was characterized by a thermal activity monitor (TAM). The local mobility of the protein system was monitored by both (13)C solid-state NMR and neutron backscattering. Annealing increased the storage stability of the protein, as shown by the smaller aggregation rate and less total aggregation at the end of a storage period. The structural relaxation time constant of an annealed sample was significantly higher than the unannealed control sample, suggesting a decrease in global mobility of the protein system upon annealing. However, annealing does not significantly impact the protein secondary structure or the local mobility. Given the similar protein native structure and specific surface area, the improved stability upon annealing is mainly a result of reduced global molecular mobility.


Assuntos
Imunoglobulina G/química , Algoritmos , Varredura Diferencial de Calorimetria , Química Farmacêutica , Cromatografia em Gel , Estabilidade de Medicamentos , Liofilização , Temperatura Alta , Espectroscopia de Ressonância Magnética , Nêutrons , Proteínas Recombinantes de Fusão/química , Espalhamento de Radiação , Espectroscopia de Infravermelho com Transformada de Fourier , Sacarose/química , Propriedades de Superfície , Temperatura Ambiente , Termodinâmica , Água/química
19.
J Pharm Sci ; 98(9): 3145-66, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19067392

RESUMO

The purpose of this study is to investigate the impact of sucrose level on storage stability of dried proteins and thus better understand the mechanism of protein stabilization by disaccharides in lyophilized protein products. Five proteins were freeze dried with different amounts of sucrose, and protein aggregation was quantified using Size Exclusion Chromatography. Protein secondary structure was monitored by FTIR. The global mobility was studied using Thermal Activity Monitor (TAM), and fast local dynamics with a timescale of nanoseconds was characterized by neutron backscattering. The density of the protein formulations was measured with a gas pycnometer. The physical stability of the proteins increased monotonically with an increasing content of sucrose over the entire range of compositions studied. Both FTIR structure and structural relaxation time from TAM achieved maxima at about 1:1 mass ratio for most proteins studied. Therefore, protein stabilization by sugar cannot be completely explained by global dynamics and FTIR structure throughout the whole range of compositions. On the other hand, both the fast local mobility and free volume obtained from density decreased monotonically with an increased level of sucrose in the formulations, and thus the local dynamics and free volume correlate well with protein storage stability.


Assuntos
Liofilização , Estabilidade Proteica , Proteínas/química , Proteínas/metabolismo , Sacarose/química , Humanos , Ligação Proteica , Conformação Proteica , Sacarose/metabolismo , Temperatura de Transição , Água/química
20.
J Pharm Sci ; 98(9): 3131-44, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19067418

RESUMO

The purpose of this study is to investigate protein-sugar interactions in dried protein solids as a function of sucrose level using water sorption isotherm data and secondary structure information from Fourier transform infrared (FTIR) spectroscopy. Three IgG1 fusion proteins and two cytokines were freeze-dried with sucrose at different sucrose/protein mass ratios. The water monolayer of the colyophilized sucrose/protein samples, as determined by BET analysis of water sorption data, was found to be lower than that expected based on additive contributions of pure protein and pure sucrose. This negative deviation suggests the presence of a solid-state interaction between protein and sucrose that reduces the availability of total water-binding sites. The difference in water monolayer between colyophilized and a physical mixture of protein and sucrose reached a maximum value at sucrose/protein mass ratio of 1/1 for these proteins, suggesting saturation of the protein-sugar interaction at this ratio. In addition, for four proteins studied, the normalized peak height of the major band in the FTIR spectra reached a plateau at about a 1/1 mass ratio. Therefore, it appears that there is a coupling between the preservation of protein secondary structure and the protein-sugar interaction as measured by water sorption isotherms.


Assuntos
Liofilização , Estabilidade Proteica , Proteínas/química , Sacarose/química , Humanos , Ligação Proteica , Conformação Proteica , Proteínas/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Sacarose/metabolismo , Água/química , Água/metabolismo
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