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1.
Anal Chem ; 95(43): 15861-15866, 2023 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-37857348

RESUMO

Transport within human tissue matrices, e.g., the subcutaneous tissue, exhibits some resemblance to chromatographic processes. Here, a porous matrix comprising agarose beads compatible with UV-vis imaging was developed for a parallel piped rectangular flow cell (4 mm light path). Introduction of high-molecular weight dextrans (Mr ∼ 200000 and ∼500000) at 10% (w/v) rendered imaging possible by providing optical clearing of the turbid porous matrix, resulting in improved transmittance as well as resolution (from 400 to 180 µm) at 280 nm, as well as 520 nm. The interplay between diffusive and convective transport at 0 < Pe ≤ 28 was visualized at 280 nm upon injection of dexamethasone suspensions. Real-time UV-vis imaging showed in-flow cell the effect of incorporating ion-exchange resins on the retention of infliximab, lysozyme, and α-lactalbumin. The ion-exchange matrix may serve as a surrogate for polyelectrolytes in the subcutaneous tissue, assessing the potential role of electrostatic interactions of biotherapeutics upon injection. UV-vis imaging of size-exclusion chromatographic matrixes may be of interest in its own right and potentially develop into a characterization tool for injectables.


Assuntos
Lactalbumina , Tela Subcutânea , Humanos , Cromatografia por Troca Iônica/métodos
2.
Int J Mol Sci ; 23(7)2022 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-35408971

RESUMO

A UV imaging release-testing setup comprising an agarose gel as a model for tumorous tissue was developed. The setup was optimized with respect to agarose concentration (0.5% (w/v)), injection procedure, and temperature control. A repeatable injection protocol was established allowing injection into cavities with well-defined geometries. The effective resolution of the SDi2 UV imaging system is 30-80 µm. The linear range of the imaging system is less than that of typical spectrophotometers. Consequently, non-linear cAMP calibration curves were applied for quantification at 280 nm. The degree of deviation from Beer's law was affected by the background absorbance of the gel matrix. MATLAB scripts provided hitherto missing flexibility with respect to definition and utilization of quantification zones, contour lines facilitating visualization, and automated, continuous data analysis. Various release patterns were observed for an aqueous solution and in situ forming Pluronic F127 hydrogel and PLGA implants containing cAMP as a model for STING ligands. The UV imaging and MATLAB data analysis setup constituted a significant technical development in terms of visualizing behavior for injectable formulations intended for intra-tumoral delivery, and, thereby, a step toward establishment of a bio-predictive in vitro release-testing method.


Assuntos
Hidrogéis , Poloxâmero , Sefarose , Temperatura
3.
Molecules ; 27(8)2022 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-35458703

RESUMO

In the development of therapeutic proteins, analytical assessment of structural stability and integrity constitutes an important activity, as protein stability and integrity influence drug efficacy, and ultimately patient safety. Existing analytical methodologies solely rely on relative changes in optical properties such as fluorescence or scattering upon thermal or chemical perturbation. Here, we present an absolute analytical method for assessing protein stability, structure, and unfolding utilizing Taylor dispersion analysis (TDA) and LED-UV fluorescence detection. The developed TDA method measures the change in size (hydrodynamic radius) and intrinsic fluorescence of a protein during in-line denaturation with guanidinium hydrochloride (GuHCl). The conformational stability of the therapeutic antibody adalimumab and human serum albumin were characterized as a function of pH. The simple workflow and low sample consumption (40 ng protein per data point) of the methodology make it ideal for assessing protein characteristics related to stability in early drug development or when having a scarce amount of sample available.


Assuntos
Hidrodinâmica , Proteínas , Guanidina , Humanos , Desnaturação Proteica , Dobramento de Proteína , Estabilidade Proteica , Proteínas/química , Albumina Sérica Humana
4.
Anal Bioanal Chem ; 413(26): 6479-6488, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34458946

RESUMO

In the present study, a method for quantitation of the pharmaceutical peptide oxytocin (OT) and its diselenide-containing analogue (SeOT) in human plasma was developed using gradient elution LC-ICP-MS/MS. Plasma samples were precipitated with acetonitrile containing 1.0% TFA in a volume ratio of 1+3 (sample+precipitation agent) before analysis. Post-column isotope dilution analysis (IDA) was applied for quantitation and was compared with external calibration. Both calibration methods appeared to be fit for purpose regarding figures of merit including linearity, precision, LOD, LOQ and recovery. Analysis of OT and SeOT showed that selenium-based analysis is considerably more sensitive and selective compared to the sulfur-based analysis. Despite the relatively simpler setup of external calibration, IDA can be advantageous because it compensates for instrument drift and changes in organic solvent concentration. The method was applied for a stability study showing the degradation of OT and SeOT in plasma. The degradation of SeOT was faster than the degradation of OT in plasma. Thus, possible stability effects should be considered before replacing a disulfide bridge with a diselenide bridge or introducing a diselenide label in a potential drug.


Assuntos
Ocitócicos/sangue , Ocitocina/sangue , Selênio/sangue , Calibragem , Cromatografia Líquida/métodos , Humanos , Técnicas de Diluição do Indicador , Limite de Detecção , Ocitócicos/análise , Ocitocina/análogos & derivados , Selênio/análise , Espectrometria de Massas em Tandem/métodos
5.
Anal Bioanal Chem ; 413(8): 2247-2255, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33580829

RESUMO

Nanoparticles (NPs) are increasingly applied in research and development of new therapies. Characterization of NP systems most often include size, shape, size distribution, and charge but information on the chemical stability of NPs and investigation of the presence of dissolved species is most often missing in efficacy studies due to lack of appropriate methods. In this study, a method based on capillary electrophoresis coupled to inductively coupled plasma mass spectrometry (CE-ICP-MS) was established for analysis of selenium (Se) NPs and dissolved Se species in aqueous media. Peak area and migration time precisions (RSD) of 1.4-3.0% and 1.0-2.6%, respectively, were obtained. CE-ICP-MS analysis of a commercially available SeNP suspension (Q-SeNP) revealed large amounts of selenite corresponding to 32% of the total Se content in the suspension, indicating considerable NP degradation upon storage. The CE-ICP-MS method was modified using a coated fused silica capillary in order to analyze SeNPs in human plasma. Peak area and migration time precisions (RSD) in the range of 3.3-10.7% and 0.8-2.8%, respectively, were achieved. Degradation of polyvinyl alcohol (PVA)-coated SeNPs to selenite in human plasma was demonstrated using the modified method. The amounts of SeNP and selenite were estimated based on a correction factor for the ICP-MS signals of PVA-SeNP and dissolved Se. To the best of our knowledge, this is the first study of SeNPs by CE-ICP-MS and highlights the potential of CE-ICP-MS for quantitative characterization of the behavior of SeNPs in biological media.


Assuntos
Nanopartículas/análise , Selênio/sangue , Eletroforese Capilar/métodos , Humanos , Espectrometria de Massas/métodos , Nanopartículas/metabolismo , Selênio/análise , Selênio/metabolismo
6.
Mol Pharm ; 17(12): 4522-4532, 2020 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-33164519

RESUMO

The initial drug release from in situ forming implants is affected by factors such as the physicochemical properties of the active pharmaceutical ingredient, the type of the excipients utilized, and the surrounding environment. The feasibility of UV-vis imaging for characterization of the initial behavior of poly(d,l-lactide-co-glycolide) (PLGA)/1-methyl-2-pyrrolidinone (NMP) in situ forming implants was investigated. The in vitro release of leuprolide acetate (LA) and implant formation in real time were monitored using dual-wavelength imaging at 280 and 525 nm, respectively, in matrices based on agarose gel and hyaluronic acid (HA) solution emulating the subcutaneous matrix. Three hours upon injection of the pre-formulation, approximately 15% of the total amount of LA administered was found in the agarose gel, while 5% was released from the implant into the HA solution. Concurrently, more extensive swelling of the implants in the HA solution as compared to implants in the agarose gel was observed. Transport of both LA and the solvent NMP was investigated using UV-vis imaging in a small-scale cell where the geometry of the formulation was controlled, showing a linear correlation between drug release and solvent escape. Light microscopy showed that the microstructures of the resulting implants in agarose gel and HA solution were different, which may be attributed to the different solvent exchange rates. UV imaging was also used to examine the interaction of LA with the release medium by characterizing the diffusion of LA in agarose gel, HA solution, and phosphate buffered saline. The reduced LA diffusivity in HA solution as compared to agarose gel and the LA distribution coefficient in the agarose gel-HA system indicated the presence of interactions between LA and HA. Our findings show that the external environment affects the solvent exchange kinetics for in situ forming implants in vitro, resulting in different types of initial release behavior. UV-vis imaging in combination with biorelevant matrices may offer an interesting approach in the development of in situ forming implant delivery systems.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Implantes de Medicamento/farmacocinética , Excipientes/química , Leuprolida/farmacocinética , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Implantes de Medicamento/administração & dosagem , Implantes de Medicamento/química , Liberação Controlada de Fármacos , Leuprolida/administração & dosagem , Leuprolida/química , Microscopia Ultravioleta , Imagem Molecular/métodos , Solubilidade
7.
Anal Chem ; 91(8): 4975-4979, 2019 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-30916933

RESUMO

Assessment of protein stability and function is key to the understanding of biological systems and plays an important role in the development of protein-based drugs. In this work, we introduce an integrated approach based on Taylor dispersion analysis (TDA), flow induced dispersion analysis (FIDA), and in-line intrinsic fluorescence which enables rapid and detailed assessment of protein stability and unfolding. We demonstrate that the new platform is able to efficiently characterize chemically induced protein unfolding of human serum albumin (HSA) in great detail. The combined platform enables local structural changes to be probed by monitoring changes in intrinsic fluorescence and loss of binding of a low-molecular weight ligand. Simultaneously, the size of the unfolding HSA is obtained by TDA on the same samples. The integration of the methodologies enables a fully automated characterization of HSA using only a few hundred nanoliters of sample. We envision that the presented methodology will find applications in fundamental biophysics and biology as well as in stability screens of protein-based drug candidates.


Assuntos
Dobramento de Proteína , Albumina Sérica/química , Albumina Sérica/metabolismo , Fluoresceína/metabolismo , Humanos , Desnaturação Proteica/efeitos dos fármacos , Ureia/farmacologia
8.
Anal Chem ; 90(11): 6413-6418, 2018 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-29746095

RESUMO

Evaluation of drug precipitation is important in order to address challenges regarding low and variable bioavailability of poorly water-soluble drugs, to assess potential risk of patient safety with infusion therapy, and to explore injectable in situ suspension-forming drug delivery systems. Generally, drug precipitation is assessed in vitro through solution concentration analysis methods. Dual-wavelength UV-vis imaging is a novel imaging technique that may provide an opportunity for simultaneously monitoring changes in both solution and solid phases during precipitation. In the present study, a multimodal approach integrating UV-vis imaging, light microscopy, and Raman spectroscopy was developed for characterization of piroxicam supersaturation, precipitation, and dissolution in a flow-through setup. A solution of piroxicam dissolved in 1-methyl-2-pyrrolidinone was injected into a flowing aqueous environment (pH 7.4), causing piroxicam to precipitate. Imaging at 405 and 280 nm monitored piroxicam concentration distributions during precipitation and revealed different supersaturation levels dependent on the initial concentration of the piroxicam solution. The combination with imaging at 525 nm, light microscopy, and Raman spectroscopy measurements demonstrated concentration-dependent precipitation and the formation, growth, and dissolution of individual particles. Results emphasize the importance of the specific hydrodynamic conditions on the piroxicam precipitation. The approach used may facilitate comprehensive understanding of drug precipitation and dissolution processes and may be developed further into a basic tool for formulation screening and development.


Assuntos
Anti-Inflamatórios não Esteroides/química , Imagem Óptica/instrumentação , Piroxicam/química , Espectrofotometria Ultravioleta/instrumentação , Precipitação Química , Microscopia/métodos , Imagem Óptica/métodos , Pirrolidinonas/química , Solubilidade , Espectrofotometria Ultravioleta/métodos , Análise Espectral Raman/métodos , Raios Ultravioleta
9.
Langmuir ; 34(22): 6570-6581, 2018 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-29768016

RESUMO

Cisplatin ( cis-diamminedichloroplatinum(II)) is among the most potent cytotoxic agents used in cancer chemotherapy. The encapsulation of cisplatin in lipid-based drug carriers has been challenging owing to its low solubility in both aqueous and lipid phases. Here, we investigated cisplatin encapsulation in nonlamellar liquid-crystalline (LC) nanodispersions formed from a ternary mixture of phytantriol (PHYT), vitamin E (Vit E), and an anionic phospholipid [either phosphatidylglycerol (DSPG) or phosphatidylserine (DPPS)]. We show an increase in cisplatin encapsulation efficiency (EE) in nanodispersions containing 1.5-4 wt % phospholipid. The EE was highest in DPPS-containing nanodispersions (53-98%) compared to DSPG-containing counterparts (25-40%) under similar experimental conditions. Through structural and morphological characterizations involving synchrotron small-angle X-ray scattering and cryogenic transmission electron microscopy, we further show that varying the phospholipid content of cisplatin-free nanodispersions triggers an internal phase transition from a neat hexagonal (H2) phase to a biphasic phase (internal H2 phase coexisting with the lamellar (Lα) phase). However, cisplatin encapsulation in both DPPS- and DSPG-containing nanodispersions generates the coexistence of morphologically different multicompartments in the internal nanostructures comprising vesicles as a core, enveloped by an inverted-type surface bicontinuous cubic Im3 m (primitive, QIIP) phase or H2 phase. We discuss the biophysical basis of these drug-induced morphological alterations and provide insights into the potential development of inverted-type LC nanodispersions for cisplatin delivery.


Assuntos
Cisplatino/química , Portadores de Fármacos/química , Cristais Líquidos/química , Nanoestruturas/química , Transição de Fase , Fosfolipídeos/química , Difração de Raios X
10.
Anal Chem ; 89(24): 13487-13493, 2017 12 19.
Artigo em Inglês | MEDLINE | ID: mdl-29120620

RESUMO

Taylor dispersion analysis (TDA) is an absolute method (no calibration needed) for the determination of the molecular diffusion coefficient (D) based on the band broadening of a solute in a laminar flow. TDA is virtually applicable to any solute with size ranging from angstrom to sub-micrometer. The higher sizing limit is restricted by the occurrence of possibly two regimes: convective and hydrodynamic chromatography (HDC) regimes, which have different physical origins that should not be confused. This work aims at clearly defining the experimental conditions for which these two regimes can play a role, alone or concomitantly. It also calculates the relative error on D due to the HDC regime according to the solute to capillary size ratio. It is demonstrated in this work that HDC does not significantly affect the TDA measurement as long as the hydrodynamic radius of the solute is lower than 0.0051 times the capillary radius. Experimental illustrations of the occurrence of the two regimes are given taking polystyrene nanoparticles as model solutes. Finally, application of TDA to the sizing of large real-life solutes is proposed, taking cubosomes as new drug nanocarriers of potential interest for drug delivery purposes.


Assuntos
Hidrodinâmica , Nanopartículas/química , Fosfatidilgliceróis/química , Poloxâmero/química , Cromatografia , Difusão , Tamanho da Partícula , Propriedades de Superfície
11.
Pharm Res ; 34(5): 929-940, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-27766463

RESUMO

Efficient drug delivery is dependent on the drug substance dissolving in the body fluids, being released from dosage forms and transported to the site of action. A fundamental understanding of the interplay between the physicochemical properties of the active compound and pharmaceutical excipients defining formulation behavior after exposure to the aqueous environments and pharmaceutical performance is critical in pharmaceutical development, manufacturing and quality control of drugs. UV imaging has been explored as a tool for qualitative and quantitative characterization of drug dissolution and release with the characteristic feature of providing real-time visualization of the solution phase drug transport in the vicinity of the formulation. Events occurring during drug dissolution and release, such as polymer swelling, drug precipitation/recrystallization, or solvent-mediated phase transitions related to the structural properties of the drug substance or formulation can be monitored. UV imaging is a non-intrusive and simple-to-operate analytical technique which holds potential for providing a mechanistic foundation for formulation development. This review aims to cover applications of UV imaging in the early and late phase pharmaceutical development with a special focus on the relation between structural properties and performance. Potential areas of future advancement and application are also discussed.


Assuntos
Preparações Farmacêuticas/química , Animais , Química Farmacêutica/métodos , Liberação Controlada de Fármacos , Excipientes/química , Humanos , Polímeros/química , Solubilidade , Espectrofotometria Ultravioleta/métodos
12.
J Sep Sci ; 40(3): 779-788, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27868374

RESUMO

Many bioanalytical methods rely on electrophoretic separation of structurally labile and surface active biomolecules such as proteins and peptides. Often poor separation efficiency is due to surface adsorption processes leading to protein denaturation and surface fouling in the separation channel. Flexible and reliable approaches for preventing unwanted protein adsorption in separation science are thus in high demand. We therefore present new coating approaches based on an automated in-capillary surface-initiated atom transfer radical polymerization process (covalent coating) as well as by electrostatically adsorbing a presynthesized polymer leading to functionalized molecular brushes. The electroosmotic flow was measured following each step of the covalent coating procedure providing a detailed characterization and quality control. Both approaches resulted in good fouling resistance against the four model proteins cytochrome c, myoglobin, ovalbumin, and human serum albumin in the pH range 3.4-8.4. Further, even samples containing 10% v/v plasma derived from human blood did not show signs of adsorbing to the coated capillaries. The covalent as well as the electrostatically adsorbed coating were both found to be stable and provided almost complete suppression of the electroosmotic flow in the pH range 3.4-8.4. The coating procedures may easily be integrated in fully automated capillary electrophoresis methodologies.


Assuntos
Análise Química do Sangue/métodos , Eletroforese Capilar/instrumentação , Polietilenoglicóis/química , Adsorção , Análise Química do Sangue/instrumentação , Citocromos c/sangue , Humanos , Mioglobina/sangue , Ovalbumina/sangue , Proteínas/metabolismo , Albumina Sérica/análise , Dióxido de Silício/química
13.
Anal Chem ; 88(18): 9056-61, 2016 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-27571264

RESUMO

Detection of immune responses is important in the diagnosis of many diseases. For example, the detection of circulating autoantibodies against double-stranded DNA (dsDNA) is used in the diagnosis of Systemic Lupus Erythematosus (SLE). It is, however, difficult to reach satisfactory sensitivity, specificity, and accuracy with established assays. Also, existing methodologies for quantification of autoantibodies are challenging to transfer to a point-of-care setting. Here we present the use of flow-induced dispersion analysis (FIDA) for rapid (minutes) measurement of autoantibodies against dsDNA. The assay is based on Taylor dispersion analysis (TDA) and is fully automated with the use of standard capillary electrophoresis (CE) based equipment employing fluorescence detection. It is robust toward matrix effects as demonstrated by the direct analysis of samples composed of up to 85% plasma derived from human blood samples, and it allows for flexible exchange of the DNA sequences used to probe for the autoantibodies. Plasma samples from SLE positive patients were analyzed using the new FIDA methodology as well as by standard indirect immunofluorescence and solid-phase immunoassays. Interestingly, the patient antibodies bound DNA sequences with different affinities, suggesting pronounced heterogeneity among autoantibodies produced in SLE. The FIDA based methodology is a new approach for autoantibody detection and holds promise for being used for patient stratification and monitoring of disease activity.


Assuntos
Anticorpos Antinucleares/imunologia , DNA/imunologia , Eletroforese Capilar/instrumentação , Imunoensaio/instrumentação , Lúpus Eritematoso Sistêmico/diagnóstico , Anticorpos Antinucleares/sangue , Ensaio de Imunoadsorção Enzimática , Desenho de Equipamento , Humanos , Lúpus Eritematoso Sistêmico/sangue , Lúpus Eritematoso Sistêmico/imunologia , Satisfação do Paciente
14.
Mol Pharm ; 13(3): 819-28, 2016 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-26808484

RESUMO

In the field of drug delivery to the articular cartilage, it is advantageous to apply artificial tissue models as surrogates of cartilage for investigating drug transport and release properties. In this study, artificial cartilage models consisting of 0.5% (w/v) agarose gel containing 0.5% (w/v) chondroitin sulfate or 0.5% (w/v) hyaluronic acid were developed, and their rheological and morphological properties were characterized. UV imaging was utilized to quantify the transport properties of the following four model compounds in the agarose gel and in the developed artificial cartilage models: H-Ala-ß-naphthylamide, H-Lys-Lys-ß-naphthylamide, lysozyme, and α-lactalbumin. The obtained results showed that the incorporation of the polyelectrolytes chondroitin sulfate or hyaluronic acid into agarose gel induced a significant reduction in the apparent diffusivities of the cationic model compounds as compared to the pure agarose gel. The decrease in apparent diffusivity of the cationic compounds was not caused by a change in the gel structure since a similar reduction in apparent diffusivity was not observed for the net negatively charged protein α-lactalbumin. The apparent diffusivity of the cationic compounds in the negatively charged hydrogels was highly dependent on the ionic strength, pointing out the importance of electrostatic interactions between the diffusant and the polyelectrolytes. Solution based affinity studies between the model compounds and the two investigated polyelectrolytes further confirmed the electrostatic nature of their interactions. The results obtained from the UV imaging diffusion studies are important for understanding the effect of drug physicochemical properties on the transport in articular cartilage. The extracted information may be useful in the development of hydrogels for in vitro release testing having features resembling the articular cartilage.


Assuntos
Biomimética , Cartilagem Articular/química , Sistemas de Liberação de Medicamentos , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Naftalenos/farmacocinética , Animais , Bovinos , Sulfatos de Condroitina/química , Ácido Hialurônico/química , Lactalbumina/química , Muramidase/química , Naftalenos/química , Reologia , Espectrofotometria Ultravioleta , Eletricidade Estática , Engenharia Tecidual
15.
Biomed Microdevices ; 17(3): 9958, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25981751

RESUMO

Microwells fabricated from poly-L-lactic acid (PLLA) were evaluated for their application as an oral drug delivery system using the amorphous sodium salt of furosemide (ASSF) as a model drug. Hot embossing of PLLA resulted in fabrication of microwells with an inner diameter of 240 µm and a height of 100 µm. The microwells were filled with ASSF using a modified screen printing technique, followed by coating of the microwell cavities with a gastro-resistant lid of Eudragit® L100. The release behavior of ASSF from the coated microwells was investigated using a µ-Diss profiler and a UV imaging system, and under conditions simulating the changing environment of the gastrointestinal tract. Biorelevant gastric medium (pH 1.6) was employed, after which a change to biorelevant intestinal release medium (pH 6.5) was carried out. Both µ-Diss profiler and UV imaging release experiments showed that sealing of microwell cavities with an Eudragit® layer prevented drug release in biorelevant gastric medium. An immediate release of the ASSF from coated microwells was observed in the intestinal medium. This pH-triggered release behavior demonstrates the future potential of PLLA microwells as a site-specific oral drug delivery system.


Assuntos
Implantes Absorvíveis , Implantes de Medicamento/síntese química , Furosemida/química , Suco Gástrico/química , Concentração de Íons de Hidrogênio , Ácido Láctico/química , Polímeros/química , Administração Oral , Cápsulas , Difusão , Implantes de Medicamento/administração & dosagem , Furosemida/administração & dosagem , Humanos , Teste de Materiais , Poliésteres
16.
Langmuir ; 31(18): 5042-9, 2015 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-25884233

RESUMO

The inverted-type liquid-crystalline dispersions comprising cubosomes and hexosomes hold much potential for drug solubilization and site-specific targeting on intravenous administration. Limited information, however, is available on the influence of plasma components on nanostructural and morphological features of cubosome and hexosome dispersions, which may modulate their stability in the blood and their overall biological performance. Through an integrated approach involving SAXS, cryo-TEM, and nanoparticle tracking analysis (NTA) we have studied the time-dependent effect of human plasma (and the plasma complement system) on the integrity of the internal nanostructure, morphology, and fluctuation in size distribution of phytantriol (PHYT)-based nonlamellar crystalline dispersions. The results indicate that in the presence of plasma the internal nanostructure undergoes a transition from the biphasic phase (a bicontinuous cubic phase with symmetry Pn3m coexisting with an inverted-type hexagonal (H2) phase) to a neat hexagonal (H2) phase, which decreases the median particle size. These observations were independent of a direct effect by serum albumin and dispersion-mediated complement activation. The implication of these observations in relation to soft nanocarrier design for intravenous drug delivery is discussed.


Assuntos
Cristais Líquidos/química , Nanoestruturas/química , Microscopia Crioeletrônica , Portadores de Fármacos/química , Álcoois Graxos/química , Humanos , Cristais Líquidos/ultraestrutura , Nanopartículas/química , Nanopartículas/ultraestrutura , Nanoestruturas/ultraestrutura
17.
Analyst ; 140(13): 4365-9, 2015 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-26031223

RESUMO

Rapid and sensitive quantification of protein based biomarkers and drugs is a substantial challenge in diagnostics and biopharmaceutical drug development. Current technologies, such as ELISA, are characterized by being slow (hours), requiring relatively large amounts of sample and being subject to cumbersome and expensive assay development. In this work a new approach for quantification based on changes in diffusivity is presented. The apparent diffusivity of an indicator molecule interacting with the protein of interest is determined by Taylor Dispersion Analysis (TDA) in a hydrodynamic flow system. In the presence of the analyte the apparent diffusivity of the indicator changes due to complexation. This change in diffusivity is used to quantify the analyte. This approach, termed Flow Induced Dispersion Analysis (FIDA), is characterized by being fast (minutes), selective (quantification is possible in a blood plasma matrix), fully automated, and being subject to a simple assay development. FIDA is demonstrated for quantification of the protein Human Serum Albumin (HSA) in human plasma as well as for quantification of an antibody against HSA. The sensitivity of the FIDA assay depends on the indicator-analyte dissociation constant which in favourable cases is in the sub-nanomolar to picomolar range for antibody-antigen interactions.


Assuntos
Proteínas Sanguíneas/análise , Análise de Injeção de Fluxo/métodos , Plasma/química , Humanos , Fatores de Tempo
18.
Anal Bioanal Chem ; 407(28): 8497-503, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26329282

RESUMO

An analytical method based on capillary electrophoresis (CE) and inductively coupled plasma mass spectrometry (ICP-MS) detection was developed for studies on the interaction of gold-containing drugs and plasma proteins using auranofin as example. A detection limit of 18 ng/mL of auranofin corresponding to 5.2 ng/mL Au and a precision of 1.5 % were obtained. Kinetic studies of the interaction between auranofin and protein were performed by incubation in aqueous solutions as well as 20 % human plasma at 37 °C. The reaction of auranofin with human serum albumin (HSA) and plasma proceeded fast; 50 % of un-bound auranofin disappeared within 2 and 3 min, respectively. By blocking the free cysteine (Cys-34) by iodoacetamide on HSA, it was shown that Cys-34 was the main reaction site for auranofin. By selective labeling of HSA present in 20 % human plasma with iophenoxate, it was demonstrated that HSA was the major auranofin-interacting protein in plasma. The CE-ICP-MS method is proposed as a novel approach for kinetic studies of the interactions between gold-based drugs and plasma proteins. Graphical Abstract Development of a CE-ICP-MS based method allows for studies on interaction of the gold containing drug auranofin with plasma proteins.


Assuntos
Antirreumáticos/sangue , Auranofina/sangue , Eletroforese Capilar/métodos , Ouro/química , Albumina Sérica/química , Espectrofotometria Atômica/métodos , Antirreumáticos/química , Auranofina/química , Cisteína/química , Humanos , Iodoacetamida/química , Ácido Iopanoico/química , Cinética , Limite de Detecção , Albumina Sérica/antagonistas & inibidores , Albumina Sérica/metabolismo , Coloração e Rotulagem/métodos
19.
Anal Bioanal Chem ; 407(10): 2829-36, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25650002

RESUMO

Human serum albumin (HSA) is the most abundant protein in the human plasma. HSA has several physiological roles in the human body, including storage and transport. Owing to the predominance of albumin in plasma, HSA is often involved in the protein binding of drugs. The aim of this work was to develop a selective, quantitative method for determining albumin in plasma with the purpose of clarifying the fate of metal-based drugs in biological systems. The method can also be applied for determination of urine albumin, which is of relevance in diagnostics of kidney disease. A selective method for quantification of HSA based on labelling the protein with iophenoxic acid (IPA) was developed. Samples were subjected to size exclusion chromatography (SEC) and detection by inductively coupled plasma mass spectrometry (ICP-MS) monitoring iodine and platinum. The iodine signal for the HSA-IPA complex showed linearity in the range 1 to 250 mg L(-1). The precision was 3.7% and the accuracy 100.7% determined by analysis of a certified HSA reference material. The limit of detection (LOD) and limit of quantification (LOQ) were 0.23 and 9.79 mg L(-1), respectively. The method was applied for analysis of HSA in human plasma and urine samples and for studying the binding of cisplatin to proteins in the human plasma.


Assuntos
Cromatografia em Gel/métodos , Ácido Iopanoico/química , Espectrometria de Massas/métodos , Albumina Sérica/análise , Albuminúria/urina , Cisplatino/metabolismo , Humanos , Limite de Detecção , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Albumina Sérica/química , Albumina Sérica/metabolismo
20.
Langmuir ; 30(22): 6398-407, 2014 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-24833115

RESUMO

Poly(ethylene glycol)-grafted 1,2-distearoyl-sn-glycero-3-phosphoethanolamines (DSPE-mPEGs) are a family of amphiphilic lipopolymers attractive in formulating injectable long-circulating nanoparticulate drug formulations. In addition to long circulating liposomes, there is an interest in developing injectable long-circulating drug nanocarriers based on cubosomes and hexosomes by shielding and coating the dispersed particles enveloping well-defined internal nonlamellar liquid crystalline nanostructures with hydrophilic PEG segments. The present study attempts to shed light on the possible PEGylation of these lipidic nonlamellar liquid crystalline particles by using DSPE-mPEGs with three different block lengths of the hydrophilic PEG segment. The effects of lipid composition, PEG chain length, and temperature on the morphology and internal nanostructure of these self-assembled lipidic aqueous dispersions based on phytantriol (PHYT) were investigated by means of synchrotron small-angle X-ray scattering and Transmission Electron Cryo-Microscopy. The results suggest that the used lipopolymers are incorporated into the water-PHYT interfacial area and induce a significant effect on the internal nanostructures of the dispersed submicrometer-sized particles. The hydrophilic domains of the internal liquid crystalline nanostructures of these aqueous dispersions are functionalized, i.e., the hydrophilic nanochannels of the internal cubic Pn3m and Im3m phases are significantly enlarged in the presence of relatively small amounts of the used DSPE-mPEGs. It is evident that the partial replacement of PHYT by these PEGylated lipids could be an attractive approach for the surface modification of cubosomal and hexosomal particles. These PEGylated nanocarriers are particularly attractive in designing injectable cubosomal and hexosomal nanocarriers for loading drugs and/or imaging probes.


Assuntos
Álcoois Graxos/química , Cristais Líquidos/química , Nanoestruturas/química , Polietilenoglicóis/química , Temperatura
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