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1.
Food Chem ; 337: 127759, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32777568

RESUMO

High-resolution ultrasonic spectroscopy (HR-US) was applied for real-time monitoring of ß-casein hydrolysis by trypsin at various conditions for the first time. The technique is based on the precision measurement of hydration changes proportional to the number of peptide bond hydrolyzed. As HR-US exhibits ultrasonic transparency for most solution, the analysis did not require optical transparency like for 2,4,6-trinitrobenzenesulfonic acid (TNBS) assay. Appropriate enzymatic models were fitted with degree of hydrolysis (dh) profiles to provide kinetic and mechanistic description of proteolysis in terms of initial hydrolysis rate, r0, and rate constant of hydrolysis, kh, and enzyme inactivation, kd. Maximal r0 and dh were obtained at 45 °C and pH 8. The exponential dependence of kinetic parameters allowed determination of the activation (EA = 50.3 ± 7 kJ/mol) and deactivation (ED = 62.23 ± 3 kJ/mol) energies of hydrolysis. The ultrasonic assay provided rapid detection of trypsin activity even at sub-nanomolar concentration.

2.
Adv Food Nutr Res ; 85: 263-310, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29860976

RESUMO

This chapter reviews recent achievements in methods of detection of mycotoxins in food. Special focus is on the biosensor technology that utilizes antibodies and nucleic acid aptamers as receptors. Development of biosensors is based on the immobilization of antibodies or aptamers onto various conventional supports like gold layer, but also on nanomaterials such as graphene oxide, carbon nanotubes, and quantum dots that provide an effective platform for achieving high sensitivity of detection using various physical methods, including electrochemical, mass sensitive, and optical. The biosensors developed so far demonstrate high sensitivity typically in subnanomolar limit of detection. Several biosensors have been validated in real samples. The sensitivity of biosensors is similar and, in some cases, even better than traditional analytical methods such as ELISA or chromatography. We believe that future trends will be focused on improving biosensor properties toward practical application in food industry.


Assuntos
Técnicas Biossensoriais , Cromatografia/métodos , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Imunoensaio/métodos , Micotoxinas/química , Animais , Análise de Alimentos/instrumentação , Humanos
3.
Colloids Surf B Biointerfaces ; 150: 373-383, 2017 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-27842930

RESUMO

The interaction of the promising drug carriers poly(alkyl cyanoacrylate) nanoparticles (PACA NPs) with lipid monolayers modeling the cell membrane and with RBE4 immortalized rat brain endothelial cells was compared to assess the relevance of lipid monolayer-based cell membrane models for PACA NP cellular uptake. NP properties such as size and charge of NPs and density of poly(ethylene glycol) coating (PEG) were kept in a narrow range to assess whether the type of PEG coating and the PACA monomer affected NP-monolayer and NP-cell interactions. The interaction with lipid monolayers was evaluated using surface pressure measurements and Brewster angle microscopy. NP association with and uptake by cells were assessed using flow cytometry and confocal laser scanning microscopy. The interaction between NPs and both lipid monolayers and the plasma membrane depended on the type of PEG. PEG density affected cellular uptake but not interaction with lipid monolayers. NP monomer, NPs size and charge had no effect on the interaction. This might be due to the fact that the size and charge distribution was kept rather narrow to study the effect of PACA monomer and PEG type. In conclusion, while modeling solely the passive aspect of NP-cell interactions, lipid monolayers nevertheless proved a valuable cell membrane model whose interaction with PACA NPs correlated well with NP-cell interaction. In addition, both NP-monolayer and NP-cell interactions were dependent on PEGylation type, which could be used in the design of NPs to either facilitate or hinder cellular uptake, depending on the intended purpose.


Assuntos
Cianoacrilatos/química , Lipídeos/química , Nanopartículas/química , Polietilenoglicóis/química , Animais , Encéfalo/metabolismo , Membrana Celular/metabolismo , Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos , Células Endoteliais/metabolismo , Citometria de Fluxo , Microscopia Confocal , Tamanho da Partícula , Fosfolipídeos/química , Polímeros/farmacologia , Ratos , Propriedades de Superfície
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