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1.
BMC Health Serv Res ; 24(1): 585, 2024 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-38704571

RESUMO

BACKGROUND: The 5.8 million Ukrainian refugees arriving in European countries must navigate varying healthcare systems and different and often unknown languages in their respective host countries. To date, there has been little exploration of the experiences, perceived differences, information and support needs of these refugees regarding the use of healthcare in Germany. METHODS: We conducted ten qualitative interviews with Ukrainian refugees living in Germany from February to May 2023, using Ukrainian, English and German language. The transcribed interviews were analysed using the qualitative content analysis method according to Kuckartz and Rädiker with the MAXQDA software. RESULTS: In general, participants consistently had a positive experience of the German healthcare system, particularly regarding the quality of treatments and insurance. Differences have been reported in the structure of the healthcare systems. The Ukrainian healthcare system is divided into private and state sectors, with no mandatory insurance and frequent out-of-pocket payments. Pathways differ and tend to focus more on clinics and private doctors. General practitioners, often working in less well-equipped offices, have only recently gained prominence due to healthcare system reforms. Initiating contact with doctors is often easier, with much shorter waiting times compared to Germany. Interviewees often found the prescription requirements for many medications in Germany to be unusual. However, the mentioned differences in healthcare result in unmet information needs among the refugees, especially related to communication, navigating the healthcare system, health insurance, waiting times and medication access. These needs were often addressed through personal internet research and informal (social media) networks because of lacking official information provided during or after their arrival. CONCLUSIONS: Despite the positive experiences of Ukrainian refugees in the German healthcare system, differences in the systems and language barriers led to barriers using healthcare and information needs among refugees. The dissemination of information regarding characteristics of the German health care system is crucial for successful integration but is currently lacking. TRIAL REGISTRATION: German Clinical Trials Register: DRKS00030942, date of registration: 29.12.2022.


Assuntos
Pesquisa Qualitativa , Refugiados , Humanos , Refugiados/psicologia , Refugiados/estatística & dados numéricos , Alemanha , Ucrânia , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Acessibilidade aos Serviços de Saúde , Entrevistas como Assunto , Atenção à Saúde , Necessidades e Demandas de Serviços de Saúde , Avaliação das Necessidades
2.
Analyst ; 145(14): 4991-5003, 2020 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-32519701

RESUMO

Over the past decade aptamers have emerged as a promising class of bioreceptors for biosensing applications with significant advantages over conventional antibodies. However, experimental studies comparing aptasensors and immunosensors, under equivalent conditions, are limited and the results are inconclusive, in terms of benefits and limitations of each bioreceptor type. In the present work, the performance of aptamer and antibody bioreceptors for the detection of a his-tagged protein, used as a model target, is compared. The bioreceptors are immobilized onto a nanostructured porous silicon (PSi) thin film, used as the optical transducer, and the target protein is detected in a real-time and label-free format by reflective interferometric Fourier transform spectroscopy. For the antibodies, random-oriented immobilization onto the PSi nanostructure results in a poor biosensing performance. Contrary, Fc-oriented immobilization of the antibodies shows a similar biosensing performance to that exhibited by the aptamer-based biosensor, in terms of binding rate, dynamic detection range, limit of detection and selectivity. The aptasensor outperforms in terms of its reusability and storability, while the immunosensor could not be regenerated for subsequent experiments.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Imunoensaio , Porosidade , Silício
3.
Sensors (Basel) ; 20(23)2020 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-33260818

RESUMO

An all-optical plasmonic sensor platform designed for smartphones based on planar-optical waveguide structures integrated in a polymer chip is reported for the first time. To demonstrate the applicability of the sensor system for biosensing purposes, the detection of 25-hydroxyvitamin D (25OHD) in human serum samples using an AuNP-enhanced aptamer-based assay was demonstrated. With the aid of the developed assay sensitivity of 0.752 pixel/nM was achieved for 25OHD concentrations ranging from 0-100 nM. The waveguide structure of the sensor enables miniaturisation and parallelisation, thus, demonstrates the potential for simultaneous detection of various analytes including biomarkers. The entire optical arrangement can be integrated into a single polymer chip which allows for large scale and cost-efficient sensor fabrication. The broad utilization and access of smartphone electronics make the proposed design most attractive for its wider use in lab-on-chip applications.


Assuntos
Técnicas Biossensoriais , Smartphone , Ressonância de Plasmônio de Superfície , Vitamina D , Feminino , Humanos , Polímeros
4.
Sensors (Basel) ; 20(10)2020 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-32443702

RESUMO

We present a surface plasmon resonance (SPR) biosensor that is based on a planar-optical multi-mode (MM) polymer waveguide structure applied for the detection of biomolecules in the lower nano-molar (nM) range. The basic sensor shows a sensitivity of 608.6 nm/RIU when exposed to refractive index changes with a measurement resolution of 4.3 × 10-3 RIU. By combining the SPR sensor with an aptamer-functionalized, gold-nanoparticle (AuNP)-enhanced sandwich assay, the detection of C-reactive protein (CRP) in a buffer solution was achieved with a response of 0.118 nm/nM. Due to the multi-mode polymer waveguide structure and the simple concept, the reported biosensor is well suited for low-cost disposable lab-on-a-chip applications and can be used with rather simple and economic devices. In particular, the sensor offers the potential for fast and multiplexed detection of several biomarkers on a single integrated platform.

5.
Sensors (Basel) ; 18(4)2018 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-29601533

RESUMO

Magnetic beads (MBs) are versatile tools for the purification, detection, and quantitative analysis of analytes from complex matrices. The superparamagnetic property of magnetic beads qualifies them for various analytical applications. To provide specificity, MBs can be decorated with ligands like aptamers, antibodies and peptides. In this context, aptamers are emerging as particular promising ligands due to a number of advantages. Most importantly, the chemical synthesis of aptamers enables straightforward and controlled chemical modification with linker molecules and dyes. Moreover, aptamers facilitate novel sensing strategies based on their oligonucleotide nature that cannot be realized with conventional peptide-based ligands. Due to these benefits, the combination of aptamers and MBs was already used in various analytical applications which are summarized in this article.


Assuntos
Separação Imunomagnética , Anticorpos , Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Técnica de Seleção de Aptâmeros
6.
Bioconjug Chem ; 27(2): 414-26, 2016 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-26567697

RESUMO

Ligands used on the surface of colloidal nanoparticles (NPs) have a significant impact on physiochemical properties of NPs and their interaction in biological environments. In this study, we report a one-pot aqueous synthesis of 3-mercaptopropionic acid (MPA)-functionalized CdTe/CdS/ZnS quantum dots (Qdots) in the presence of thiol-terminated methoxy polyethylene glycol (mPEG) molecules as a surface coordinating ligand. The resulting mPEG-Qdots were characterized by using ζ potential, FTIR, thermogravimetric (TG) analysis, and microscale thermophoresis (MST) studies. We investigated the effect of mPEG molecules and their grafting density on the Qdots photophysical properties, colloidal stability, protein binding affinity, and in vitro cellular toxicity. Moreover, cellular binding features of the resulting Qdots were examined by using three-dimensional (3D) tumor-like spheroids, and the results were discussed in detail. Promisingly, mPEG ligands were found to increase colloidal stability of Qdots, reduce adsorption of proteins to the Qdot surface, and mitigate Qdot-induced side effects to a great extent. Flow cytometry and confocal microscopy studies revealed that PEGylated Qdots exhibited distinctive cellular interactions with respect to their mPEG grafting density. As a result, mPEG molecules demonstrated a minimal effect on the ZnS shell deposition and the Qdot fluorescence efficiency at a low mPEG density, whereas they showed pronounced effect on Qdot colloidal stability, protein binding affinity, cytotoxicity, and nonspecific binding at a higher mPEG grafting amount.


Assuntos
Compostos de Cádmio/química , Polietilenoglicóis/química , Pontos Quânticos/química , Sulfetos/química , Telúrio/química , Compostos de Zinco/química , Ácido 3-Mercaptopropiônico/química , Ácido 3-Mercaptopropiônico/toxicidade , Animais , Compostos de Cádmio/toxicidade , Bovinos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Coloides/química , Coloides/toxicidade , Humanos , Polietilenoglicóis/toxicidade , Agregados Proteicos/efeitos dos fármacos , Pontos Quânticos/toxicidade , Pontos Quânticos/ultraestrutura , Soroalbumina Bovina/química , Sulfetos/toxicidade , Telúrio/toxicidade , Água/química , Compostos de Zinco/toxicidade
7.
Anal Chem ; 87(3): 1999-2006, 2015 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-25551423

RESUMO

A proof-of-concept for a label-free and reagentless optical biosensing platform based on nanostructured porous silicon (PSi) and aptamers is presented in this work. Aptamers are oligonucleotides (single-stranded DNA or RNA) that can bind their targets with high affinity and specificity, making them excellent recognition elements for biosensor design. Here we describe the fabrication and characterization of aptamer-conjugated PSi biosensors, where a previously characterized his-tag binding aptamer (6H7) is used as model system. Exposure of the aptamer-functionalized PSi to the target proteins as well as to complex fluids (i.e., bacteria lysates containing target proteins) results in robust and well-defined changes in the PSi optical interference spectrum, ascribed to specific aptamer-protein binding events occurring within the nanoscale pores, monitored in real time. The biosensors show exceptional stability and can be easily regenerated by a short rinsing step for multiple biosensing analyses. This proof-of-concept study demonstrates the possibility of designing highly stable and specific label-free optical PSi biosensors, employing aptamers as capture probes, holding immense potential for application in detection of a broad range of targets, in a simple yet reliable manner.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/instrumentação , Histidina/análise , Nanoestruturas/química , Oligopeptídeos/análise , Silício/química , Porosidade
8.
Anal Chem ; 87(1): 677-85, 2015 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-25435319

RESUMO

Aptamers are promising recognition elements for sensitive and specific detection of small molecules. We have previously selected ssDNA aptamers for ethanolamine, one of the smallest aptamer targets so far. The work presented here focuses on the determination of the binding region within the aptamer structure and its exploitation for the development of an aptamer-based assay for detection of ethanolamine. Sequence analysis of the aptamers resulted in the identification of a G-rich consensus sequence, which was able to fold in a typical two- or three-layered G-quartet structure. Experiments with stepwise truncated variants of the aptamers revealed that the consensus sequence is responsible and sufficient for binding to the target. On the basis of the knowledge of the aptamers binding site, we developed an aptamer-based microarray assay relying on competition between ethanolamine and an oligonucleotide complementary to the consensus sequence. Competitive binding of ethanolamine and fluorescently labeled complementary oligonucleotides resulted in fluorescence intensities dependent on ethanolamine concentration with a limit of detection of 10 pM. This method enables detection of small molecules without any labeling of analytes. The competitive assay could potentially be transferred to other aptamers and thus provides a promising system for aptamer-based detection of diverse small molecules.


Assuntos
Aptâmeros de Nucleotídeos/metabolismo , Técnicas Biossensoriais/métodos , Etanolaminas/análise , Etanolaminas/metabolismo , Corantes Fluorescentes/química , Aptâmeros de Nucleotídeos/química , Sequência de Bases , Sítios de Ligação , Ligação Competitiva , Etanolaminas/química , Dados de Sequência Molecular
9.
Chembiochem ; 16(2): 302-11, 2015 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-25572106

RESUMO

Streptomyces hygroscopicus is a natural producer of geldanamycin. Mutasynthetic supplementation of an AHBA-blocked mutant with all possible monofluoro 3-aminobenzoic acids provided new fluorogeldanamycins. These showed strong antiproliferative activity and inhibitory effects on human heat shock protein Hsp90. Binding to Hsp90 in the low nanomolar range was determined from molecular modelling, AFM analysis and by calorimetric studies.


Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Benzoquinonas/química , Proteínas de Choque Térmico HSP90/antagonistas & inibidores , Lactamas Macrocíclicas/química , Streptomyces/metabolismo , Antineoplásicos/metabolismo , Calorimetria/métodos , Linhagem Celular Tumoral/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Fluorbenzenos/metabolismo , Fluorbenzenos/farmacologia , Proteínas de Choque Térmico HSP90/metabolismo , Humanos , Espectroscopia de Ressonância Magnética , Microscopia de Força Atômica , Modelos Moleculares , Quinonas/química , Streptomyces/genética , meta-Aminobenzoatos/metabolismo , meta-Aminobenzoatos/farmacologia
10.
J Exp Biol ; 217(Pt 2): 235-43, 2014 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-24072801

RESUMO

For low-energy organisms such as bivalves, the costs of thermal compensation of biological rates (synonymous with acclimation or acclimatization) may be higher than the benefits. We therefore conducted two experiments to examine the effect of seasonal temperature changes on behaviour and oxygen consumption. In the first experiment, we examined the effects of seasonal temperature changes on the freshwater bivalve Anodonta anatina, taking measurements each month for a year at the corresponding temperature for that time of year. There was no evidence for compensation of burrowing valve closure duration or frequency, or locomotory speed. In the second experiment, we compared A. anatina at summer and winter temperatures (24 and 4°C, respectively) and found no evidence for compensation of the burrowing rate, valve closure duration or frequency, or oxygen consumption rates during burrowing, immediately after valve closure or at rest. Within the experimental limits of this study, the evidence suggests that thermal compensation of biological rates is not a strategy employed by A. anatina. We argue that this is due to either a lack of evolutionary pressure to acclimatize, or evolutionary pressure to not acclimatize. Firstly, there is little incentive to increase metabolic rate to enhance predatory ability given that these are filter feeders. Secondly, maintained low energetic demand, enhanced at winter temperatures, is essential for predator avoidance, i.e. valve closure. Thus, we suggest that the costs of acclimatization outweigh the benefits in A. anatina.


Assuntos
Anodonta/fisiologia , Aclimatação , Animais , Movimento , Consumo de Oxigênio , Respiração , Estações do Ano , Temperatura
11.
J Therm Biol ; 43: 13-23, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24956953

RESUMO

Temperature plays a critical role in determining the biology of ectotherms. Many animals have evolved mechanisms that allow them to compensate biological rates, i.e. adjust biological rates to overcome thermodynamic effects. For low energy-organisms, such as bivalves, the costs of thermal compensation may be greater than the benefits, and thus prohibitive. To examine this, two experiments were designed to explore thermal compensation in Unio tumidus. Experiment 1 examined seasonal changes in behaviour in U. tumidus throughout a year. Temperature had a clear effect on burrowing rate with no evidence of compensation. Valve closure duration and frequency were also strongly affected by seasonal temperature change, but there was slight evidence of partial compensation. Experiment 2 examined oxygen consumption during burrowing, immediately following valve opening and at rest in summer (24 °C), autumn (14 °C), winter (4 °C), and spring (14 °C) acclimatized U. tumidus. Again, there was little evidence of burrowing rate compensation, but some evidence of partial compensation of valve closure duration and frequency. None of the oxygen compensation rates showed any evidence of thermal compensation. Thus, in general, there was only very limited evidence of thermal compensation of behaviour and no evidence of thermal compensation of oxygen compensation rates. Based upon this evidence, we argue that there is no evolutionary pressure for these bivalves to compensate these biological rates. Any pressure may be to maintain or even lower oxygen consumption as their only defence against predation is to close their valves and wait. An increase in oxygen consumption will be detrimental in this regard so the cost of thermal compensation may outweigh the benefits.


Assuntos
Comportamento Animal/fisiologia , Unio/fisiologia , Aclimatação , Animais , Água Doce , Consumo de Oxigênio , Estações do Ano , Temperatura
12.
Cell Tissue Res ; 353(1): 117-22, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23579552

RESUMO

Efficient cell expansion is a basic requirement for obtaining clinically relevant numbers of mesenchymal stem cells designed for cell-based therapies or tissue-engineering application. Previous studies have demonstrated that mesenchymal stem cells (MSC) cultivated under reduced atmospheric oxygen concentrations (2.5% O2) possess enhanced proliferation potential and can maintain their differentiation properties. We have analyzed the oxygen-dependent cytokine expression of human MSC derived from umbilical cord and attempted to link the results to the proliferation and differentiation capacities of these cells. By quantitative reverse transcription plus the polymerase chain reaction and by protein microarray, we measured the gene expression and intracellular protein concentration of several growth factors and growth factor receptors. Fibroblast growth factor-7, two growth factor receptors (vascular endothelial growth factor receptor 2 and stem cell factor receptor), and two growth-factor-binding proteins (insulin-like growth-factor-binding proteins 3 and 6) were over-expressed under hypoxic conditions, indicating that their signaling pathways participate in cell proliferation. On the other hand, typical differentiation factors such as bone morphogenetic protein-4, endothelial growth factor, and tissue growth factor-ß1 were absent in cells cultivated under hypoxic and normoxic conditions. The absolute concentration of some intracellular cytokines was also measured for the first time under hypoxia and normoxia. Our results in combination with previous findings indicate that enhanced proliferation potential and a maintained undifferentiated cell state can be ascribed to the oxygen-dependent expression of a set of cytokines. This knowledge might help in the understanding of MSC physiology and in the achievement of directed cell fate of MSC for clinical application.


Assuntos
Hipóxia Celular/fisiologia , Células-Tronco Mesenquimais/metabolismo , Oxigênio/metabolismo , Cordão Umbilical/metabolismo , Proteína Morfogenética Óssea 4/deficiência , Diferenciação Celular , Proliferação de Células , Células Cultivadas , Fatores de Crescimento Endotelial/deficiência , Fator 7 de Crescimento de Fibroblastos/biossíntese , Fator 7 de Crescimento de Fibroblastos/metabolismo , Expressão Gênica , Humanos , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/biossíntese , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/metabolismo , Proteína 6 de Ligação a Fator de Crescimento Semelhante à Insulina/biossíntese , Proteína 6 de Ligação a Fator de Crescimento Semelhante à Insulina/metabolismo , Proteínas Proto-Oncogênicas c-kit/biossíntese , Proteínas Proto-Oncogênicas c-kit/metabolismo , Fator de Crescimento Transformador beta1/biossíntese , Cordão Umbilical/citologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/biossíntese , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismo
13.
Appl Microbiol Biotechnol ; 97(16): 7097-109, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23838792

RESUMO

Aptamers are nucleic acid oligomers with distinct conformational shapes that allow them to bind targets with high affinity and specificity. Aptamers are selected from a random oligonucleotide library by their capability to bind a certain molecular target. A variety of targets ranging from small molecules like amino acids to complex targets and whole cells have been used to select aptamers. These characteristics and the ability to create specific aptamers against virtually any cell type in a process termed "systematic evolution by exponential enrichment" make them interesting tools for flow cytometry. In this contribution, we review the application of aptamers as probes for flow cytometry, especially cell-phenotyping and detection of various cancer cell lines and virus-infected cells and pathogens. We also discuss the potential of aptamers combined with nanoparticles such as quantum dots for the generation of new multivalent detector molecules with enhanced affinity and sensitivity. With regard to recent advancements in aptamer selection and the decreasing costs for oligonucleotide synthesis, aptamers may rise as potent competitors for antibodies as molecular probes in flow cytometry.


Assuntos
Aptâmeros de Nucleotídeos/metabolismo , Citometria de Fluxo/métodos , Aptâmeros de Nucleotídeos/isolamento & purificação , Técnica de Seleção de Aptâmeros
14.
ACS Omega ; 7(16): 13475-13493, 2022 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-35559140

RESUMO

Hypericum perforatum Linn (St. John's wort) is a popular and widespread medicine in Syria, which is used for a wide range of conditions, including gastrointestinal diseases, heart disease, skin diseases, and psychological disorders. This widespread use prompted us to identify the main compounds of this plant from Syria that are responsible for its medicinal properties, especially since its components differ between countries according to the nature of the soil, climate, and altitude. This is, to the best of our knowledge, the first report in which St. John's wort, a plant native to Syria, is extracted using different solvents and its most important compounds are identified. In this study, the dried above-ground parts, i.e., leaves, stem, petals, and flowers, were extracted using different solvents (water, ethanol, methanol, and acetone) and extraction protocols. By increasing the polarity of the solvent, higher yields were obtained, indicating that mainly hydrophobic compounds were extracted. Therefore, we conclude that extraction using the tea method or using a mixture of water and organic solvents resulted in higher yields compared with pure organic solvents or continuous boiling with water for long periods. The obtained extracts were analyzed using high-performance liquid chromatography equipped with a diode array detector (HPLC-DAD), coupled with UV-visible spectrophotometry at a full spectrum (200-800 nm). The HPLC spectra of the extracts were almost identical at three wavelengths (260 nm for phloroglucinols (hyperforin and derivates), 590 nm for naphthodianthrones (hypericins), and 350 nm for other flavonols, flavones, and caffeoylquinic acids), with differences observed only in the intensity of the peaks. This indicates that the same compounds were obtained using different solvents, but in different amounts. Five standards (chlorogenic acid, quercetin, quercitrin hydrate, hyperoside, and hypericin) were used, and a comparison with retention times and ultraviolet (UV) spectra reported in the literature was performed to identify 10 compounds in these extracts: hyperforin, adhyperforin, hypericin, rutin, quercetin, quercitrin, quercitrin hydrate, hyperoside, biapigenin, and chlorogenic acid. Although the European Pharmacopoeia still describes ultraviolet spectroscopy as a method for determining the quantity of Hyperici herba, interference from other metabolites can occur. Combined HPLC-DAD and electrospray ionization-mass spectrometry (LC-ESI-MS) in the positive mode have therefore also been used to confirm the presence of these compounds in the extracts by correlating known masses with the identified masses or through characteristic fragmentation patterns. Total phenolic contents of the extracts were determined by the Folin-Ciocalteu assay, and antioxidant activity was evaluated as free radical scavenging capacity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. The results indicate that the aqueous extracts prepared by the tea method gave the highest total phenols, while the pure organic solvents gave very low phenols. Also, the extracts that contain the largest amount of phenols gave lower IC50 values or higher antioxidant activity than that of others.

15.
Pharmaceutics ; 14(5)2022 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-35631691

RESUMO

The rapid development of nanotechnology and its applications in medicine has provided the perfect solution against a wide range of different microbes, especially antibiotic-resistant ones. In this study, a one-step approach was used in preparing silver nanoparticles (AgNPs) by mixing silver nitrate with hot Hypericum perforatum (St. John's wort) aqueous extract under high stirring to prevent agglomeration. The formation of silver nanoparticles was monitored by continuous measurement of the surface plasma resonance spectra (UV-VIS). The effect of St. John's wort aqueous extract on the formation of silver nanoparticles was evaluated and fully characterized by using different physicochemical techniques. The obtained silver nanoparticles were spherical, monodisperse, face-centered cubic (fcc) crystal structures, and the size ranges between 20 to 40 nm. They were covered with a capping layer of organic compounds considered as a nano dimension protective layer that prevents agglomeration and sedimentation. AgNPs revealed antibacterial activity against both tested Gram-positive and Gram-negative bacterial strains causing the formation of 13-32 mm inhibition zones with MIC 6.25-12.5 µg/mL; Escherichia coli strains were resistant to tested AgNPs. The specific growth rate of S. aureus was significantly reduced due to tested AgNPs at concentrations ≥½ MIC. AgNPs did not affect wound migration in fibroblast cell lines compared to control. Our results highlighted the potential use of AgNPs capped with plant extracts in the pharmaceutical and food industries to control bacterial pathogens' growth; however, further studies are required to confirm their wound healing capability and their health impact must be critically evaluated.

16.
Biotechnol Bioeng ; 108(10): 2371-9, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21538335

RESUMO

Aptamers are synthetic nucleic acid-based high affinity ligands that are able to capture their corresponding target via molecular recognition. Here, aptamer-based affinity purification for His-tagged proteins was developed. Two different aptamers directed against the His-tag were immobilized on magnetic beads covalently. The resulting aptamer-modified magnetic beads were characterized and successfully applied for purification of different His-tagged proteins from complex E. coli cell lysates. Purification effects comparable to conventional immobilized metal affinity chromatography were achieved in one single purification step. Moreover, we have investigated the possibility to regenerate and reuse the aptamer-modified magnetic beads and have shown their long-term stability over a period of 6 months.


Assuntos
Aptâmeros de Nucleotídeos/química , Proteínas de Bactérias/química , Proteínas de Bactérias/isolamento & purificação , Histidina/química , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/isolamento & purificação , Estabilidade Proteica
17.
Adv Biochem Eng Biotechnol ; 178: 147-168, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33796881

RESUMO

Hydrogels have attracted much attention especially due to their biocompatibility and their potential for stimulus responsiveness. By combining hydrogels with aptamers, biological recognition and responsiveness can be added to hydrogels, thereby opening path to advanced applications in biosensing and biomedicine. Within this chapter aptamers will be introduced and their contributions to biological responsiveness of hydrogels will be described. Especially the aptamer-based mechanisms that result in biological responsiveness will be explained and examples for the application of these mechanisms will be given ranging from rather simple sensing approaches to advanced materials for tissue engineering and drug delivery. Since aptamers are not only highly specific bioreceptors, but represent switchable structures that can be easily manipulated using well-known DNA techniques, the combination of aptamers and hydrogels facilitates the rational design of well-programmable and target-responsive smart hydrogels.


Assuntos
Aptâmeros de Nucleotídeos , Hidrogéis , DNA/genética , Sistemas de Liberação de Medicamentos
18.
Nanomaterials (Basel) ; 11(2)2021 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-33673018

RESUMO

This contribution focuses on the green synthesis of silver nanoparticles (AgNPs) with a size < 100 nm for potential medical applications by using silver nitrate solution and Hypericum Perforatum L. (St John's wort) aqueous extracts. Various synthesis methods were used and compared with regard to their yield and quality of obtained AgNPs. Monodisperse spherical nanoparticles were generated with a size of approximately 20 to 50 nm as elucidated by different techniques (SEM, TEM). XRD measurements showed that metallic silver was formed and the particles possess a face-centered cubic structure (fcc). SEM images and FTIR spectra revealed that the AgNPs are covered by a protective surface layer composed of organic components originating from the plant extract. Ultraviolet-visible spectroscopy, dynamic light scattering, and zeta potential were also measured for biologically synthesized AgNPs. A potential mechanism of reducing silver ions to silver metal and protecting it in the nanoscale form has been proposed based on the obtained results. Moreover, the AgNPs prepared in the present study have been shown to exhibit a high antioxidant activity for 2, 2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation, and super oxide anion radical and 2,2-diphenyl-1-picrylhydrazyl. Synthesized AgNPs showed high cytotoxicity by inhibiting cell viability for Hela, Hep G2, and A549 cells.

19.
J Nanobiotechnology ; 8: 21, 2010 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-20731831

RESUMO

BACKGROUND: Bio-conjugated nanoparticles are important analytical tools with emerging biological and medical applications. In this context, in situ conjugation of nanoparticles with biomolecules via laser ablation in an aqueous media is a highly promising one-step method for the production of functional nanoparticles resulting in highly efficient conjugation. Increased yields are required, particularly considering the conjugation of cost-intensive biomolecules like RNA aptamers. RESULTS: Using a DNA aptamer directed against streptavidin, in situ conjugation results in nanoparticles with diameters of approximately 9 nm exhibiting a high aptamer surface density (98 aptamers per nanoparticle) and a maximal conjugation efficiency of 40.3%. We have demonstrated the functionality of the aptamer-conjugated nanoparticles using three independent analytical methods, including an agglomeration-based colorimetric assay, and solid-phase assays proving high aptamer activity. To demonstrate the general applicability of the in situ conjugation of gold nanoparticles with aptamers, we have transferred the method to an RNA aptamer directed against prostate-specific membrane antigen (PSMA). Successful detection of PSMA in human prostate cancer tissue was achieved utilizing tissue microarrays. CONCLUSIONS: In comparison to the conventional generation of bio-conjugated gold nanoparticles using chemical synthesis and subsequent bio-functionalization, the laser-ablation-based in situ conjugation is a rapid, one-step production method. Due to high conjugation efficiency and productivity, in situ conjugation can be easily used for high throughput generation of gold nanoparticles conjugated with valuable biomolecules like aptamers.

20.
Adv Biochem Eng Biotechnol ; 170: 107-119, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-30847536

RESUMO

Aptazymes are synthetic molecules composed of an aptamer domain and a catalytic active nucleic acid unit, which may be a ribozyme or a DNAzyme. In these constructs the aptamer domain serves as a molecular switch that can regulate the catalytic activity of the ribozyme or DNAzyme subunit. This regulation is triggered by binding of the aptamers target molecule, which causes significant structural changes in the aptamer and thus in the entire aptazyme. Therefore, aptazymes function similar to allosteric enzymes, whose catalytic activity is regulated by binding of ligands (effectors) to allosteric sites due to alteration of the three-dimensional structure of the active site of the enzyme. In case of aptazymes, the allosteric site is composed of an aptamer. Aptazymes can be designed for different applications and have already been used in analytical assays as well as for the regulation of gene expression.


Assuntos
Aptâmeros de Nucleotídeos , DNA Catalítico , RNA Catalítico , Aptâmeros de Nucleotídeos/química , Catálise , DNA Catalítico/química , DNA Catalítico/metabolismo , Ligantes , Ligação Proteica , RNA Catalítico/química , RNA Catalítico/metabolismo
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