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1.
Biosens Bioelectron ; 172: 112724, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33142197

RESUMO

The uneven morphology and the trapped charges at the surface of the traditionally used supporting substrate-based 2D biosensors produces a scattering effect, which leads to a irregular signals from individually fabricated devices. Though suspended 2D channel material has the potential to overcome scattering effects from the substrates but achieving reliability and selectivity, have been limiting the using of this biosensor technology. Here, we have demonstrated nanogap electrodes fabrication by using the self-assembly technique, which provides suspension to the 2D-MoS2. These nano-spacing electrodes not only give suspension but also provide robustness strength to the atomic layer, which remains freestanding after coating of the Hafnium oxide (HfO2) as well as linkers and antibodies. For evaluating the electrical characteristics of suspended MoS2 FET, gating potential was applied through an electrolyte on the suspended MoS2 transistor. This helped in achieved a lower subthreshold swing 70 mV/dec and ON/OFF ratio 107. Later, pH detection was conducted at room temperature, which showed an impressive sensitivity of ~880 by changing 1 unit of pH. We have also successfully shown Escherichia coli (E. coli) bacteria sensing from the suspended MoS2 transistor by functionalizing dielectric layer with E. coli antibodies. The reported biosensor has shown the ~9% of conductance changes with a lower concentration of E. coli (10 CFU/mL; colony-forming unit per mL) as well as maintain the constant sensitivity in three fabricated devices. The obtained enhancement in the sensitivity of devices and its effect on biomolecules detection can be extened to other biomolecules and this type of architecture has the potential to detect COVID-19 viruses based biomolecules.


Assuntos
Técnicas Biossensoriais/métodos , Dissulfetos , Molibdênio , Nanoestruturas/química , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/estatística & dados numéricos , /virologia , Materiais Revestidos Biocompatíveis/química , Escherichia coli/química , Escherichia coli/isolamento & purificação , Humanos , Concentração de Íons de Hidrogênio , Microeletrodos , Microtecnologia , Reprodutibilidade dos Testes , /isolamento & purificação , Sensibilidade e Especificidade , Eletricidade Estática , Volatilização
2.
J Vis Exp ; (165)2020 11 17.
Artigo em Inglês | MEDLINE | ID: mdl-33283789

RESUMO

Sand flies are the natural vectors for Leishmania species, protozoan parasites producing a broad spectrum of symptoms ranging from cutaneous lesions to visceral pathology. Deciphering the nature of the vector/parasite interactions is of primary importance for better understanding of Leishmania transmission to their hosts. Among the parameters controlling the sand fly vector competence (i.e. their ability to carry and transmit pathogens), parameters intrinsic to these insects were shown to play a key role. Insect immune response, for example, impacts sand fly vector competence to Leishmania. The study of such parameters has been limited by the lack of methods of gene expression modification adapted for use in these non-model organisms. Gene downregulation by small interfering RNA (siRNA) is possible, but in addition to being technically challenging, the silencing leads to only a partial loss of function, which cannot be transmitted from generation to generation. Targeted mutagenesis by CRISPR/Cas9 technology was recently adapted to the Phlebotomus papatasi sand fly. This technique leads to the generation of transmissible mutations in a specifically chosen locus, allowing to study the genes of interest. The CRISPR/Cas9 system relies on the induction of targeted double-strand DNA breaks, later repaired by either Non-Homologous End Joining (NHEJ) or by Homology Driven Repair (HDR). NHEJ consists of a simple closure of the break and frequently leads to small insertion/deletion events. In contrast, HDR uses the presence of a donor DNA molecule sharing homology with the target DNA as a template for repair. Here, we present a sand fly embryo microinjection method for targeted mutagenesis by CRISPR/Cas9 using NHEJ, which is the only genome modification technique adapted to sand fly vectors to date.


Assuntos
Proteína 9 Associada à CRISPR/metabolismo , Sistemas CRISPR-Cas/genética , Embrião não Mamífero/metabolismo , Microinjeções , Mutagênese/genética , Phlebotomus/embriologia , Animais , Feminino , Masculino , Camundongos , Microtecnologia , Mutação/genética , Agulhas , Phlebotomus/genética , Phlebotomus/imunologia , Phlebotomus/parasitologia
3.
Small ; 16(45): e2003844, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33078567

RESUMO

Recent studies have shown a correlation between elevated interleukin 6 (IL-6) concentrations and the risk of respiratory failure in COVID-19 patients. Therefore, detection of IL-6 at low concentrations permits early diagnosis of worst-case outcome in viral respiratory infections. Here, a versatile biointerface is presented that eliminates nonspecific adhesion and thus enables immunofluorescence detection of IL-6 in whole human plasma or whole human blood during coagulation, down to a limit of detection of 0.5 pg mL-1 . The sensitivity of the developed lubricant-infused biosensor for immunofluorescence assays in detecting low molecular weight proteins such as IL-6 is facilitated by i) producing a bioink in which the capture antibody is functionalized by an epoxy-based silane for covalent linkage to the fluorosilanized surface and ii) suppressing nonspecific adhesion by patterning the developed bioink into a lubricant-infused coating. The developed biosensor addresses one of the major challenges for biosensing in complex fluids, namely nonspecific adhesion, therefore paving the way for highly sensitive biosensing in complex fluids.


Assuntos
Anticorpos/metabolismo , Técnicas Biossensoriais/métodos , Interleucina-6/sangue , Lubrificantes/química , Microtecnologia , Fluorescência , Imunofluorescência , Humanos , Espectroscopia Fotoeletrônica , Polimetil Metacrilato/química , Padrões de Referência
4.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4314-4317, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018950

RESUMO

Advanced polymer science and design technologies are constantly evolving to meet ever-growing expectations for flexible optical MEMS. In this work, we present design and microfabrication considerations for designed flexible Polymeric Opto-Electro-Mechanical Systems (POEMS). The presented methods integrate waveguide fabrication and laser diode (LD) chip assembly with Lawrence Livermore National Laboratory's (LLNL's) flexible thin-film technology to enable LLNL's first neural optoelectrode that can deliver guided light for neural activation. We support our findings with electrical and optical bench verification tests, present thermal simulation models to analyze heat dissipation of laser light sources on polymer substrates and discuss potential modifications for next generation prototypes. This fully integrated approach will allow spatial precision, scalability and more particularly, longer lifetime, needed to enable chronic studies of brain activities.


Assuntos
Microtecnologia , Próteses e Implantes , Eletricidade , Polímeros
5.
J Chromatogr A ; 1629: 461484, 2020 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-32889297

RESUMO

Isomers, holding similar chemical and physical properties, are difficult to separate especially by utilizing a microfabricated gas chromatography system due to limited column lengths mainly imposed by low-pressure (<20 kPa) micropump capability. In this paper, we demonstrated the separation of a pair of structural isomers, isopentane and pentane, in a micro-scale gas chromatography system with a circulatory loop of two 25-cm micro open tubular columns, while operating under a minimal pressure requirement of <10 kPa. The developed micro circulatory gas chromatography (MCGC) system achieved an effective column length of 12.5 meters by circulating the isomer gases for 25 cycles, the longest micro open tubular column length ever reported by any microfabricated GC systems yet.


Assuntos
Cromatografia Gasosa/métodos , Pentanos/isolamento & purificação , Isomerismo , Microtecnologia
6.
Sci Rep ; 10(1): 15470, 2020 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-32963304

RESUMO

Biofilm colonisation of surfaces is of critical importance in various areas ranging from indwelling medical devices to industrial setups. Of particular importance is the reduced susceptibility of bacteria embedded in a biofilm to existing antimicrobial agents. In this paper, we demonstrate that remotely actuated magnetic cantilevers grafted on a substrate act efficiently in preventing bacterial biofilm formation. When exposed to an alternating magnetic field, the flexible magnetic cantilevers vertically deflect from their initial position periodically, with an extremely low frequency (0.16 Hz). The cantilevers' beating prevents the initial stage of bacterial adhesion to the substrate surface and the subsequent biofilm growth. Our experimental data on E. coli liquid cultures demonstrate up to a 70% reduction in biofilm formation. A theoretical model has been developed to predict the amplitude of the cantilevers vertical deflection. Our results demonstrate proof-of-concept for a device that can magneto-mechanically prevent the first stage in bacterial biofilm formation, acting as on-demand fouling release active surfaces.


Assuntos
Antibacterianos/administração & dosagem , Biofilmes/crescimento & desenvolvimento , Infecções por Escherichia coli/prevenção & controle , Escherichia coli/crescimento & desenvolvimento , Magnetismo , Microtecnologia/instrumentação , Aderência Bacteriana , Biofilmes/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Infecções por Escherichia coli/microbiologia , Humanos , Tamanho da Partícula , Propriedades de Superfície
7.
PLoS One ; 15(8): e0236643, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32841239

RESUMO

Accelerometry is a recent method used to quantify workload in team sports. A rapidly increasing number of studies supports the practical implementation of accelerometry monitoring to regulate and optimize training schemes. Therefore, the purposes of this study were: (1) to reflect the current state of knowledge about accelerometry as a method of workload monitoring in invasion team sports according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, and (2) to conclude recommendations for application and scientific investigations. The Web of Science, PubMed and Scopus databases were searched for relevant published studies according to the following keywords: "accelerometry" or "accelerometer" or "microtechnology" or "inertial devices", and "load" or "workload", and "sport". Of the 1383 studies initially identified, 118 were selected for a full review. The main results indicate that the most frequent findings were (i) devices' body location: scapulae; (b) devices brand: Catapult Sports; (iii) variables: PlayerLoadTM and its variations; (iv) sports: rugby, Australian football, soccer and basketball; (v) sex: male; (vi) competition level: professional and elite; and (vii) context: separate training or competition. A great number of variables and devices from various companies make the comparability between findings difficult; unification is required. Although the most common location is at scapulae because of its optimal signal reception for time-motion analysis, new methods for multi-location skills and locomotion assessment without losing tracking accuracy should be developed.


Assuntos
Acelerometria , Desempenho Atlético , Basquetebol , Futebol Americano , Futebol , Carga de Trabalho , Feminino , Sistemas de Informação Geográfica , Humanos , Masculino , Microtecnologia
8.
Nat Commun ; 11(1): 4191, 2020 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-32826892

RESUMO

The nascent field of bioelectronic medicine seeks to decode and modulate peripheral nervous system signals to obtain therapeutic control of targeted end organs and effectors. Current approaches rely heavily on electrode-based devices, but size scalability, material and microfabrication challenges, limited surgical accessibility, and the biomechanically dynamic implantation environment are significant impediments to developing and deploying peripheral interfacing technologies. Here, we present a microscale implantable device - the nanoclip - for chronic interfacing with fine peripheral nerves in small animal models that begins to meet these constraints. We demonstrate the capability to make stable, high signal-to-noise ratio recordings of behaviorally-linked nerve activity over multi-week timescales. In addition, we show that multi-channel, current-steering-based stimulation within the confines of the small device can achieve multi-dimensional control of a small nerve. These results highlight the potential of new microscale design and fabrication techniques for realizing viable devices for long-term peripheral interfacing.


Assuntos
Microeletrodos , Nervos Periféricos/fisiologia , Impressão Tridimensional , Animais , Engenharia Biomédica , Eletrodos Implantados , Potenciais Evocados , Tentilhões/fisiologia , Masculino , Microtecnologia , Modelos Animais , Nervos Periféricos/cirurgia , Razão Sinal-Ruído
9.
Am J Respir Cell Mol Biol ; 63(5): 591-600, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32706623

RESUMO

Viral-induced exacerbation of asthma remains a major cause of hospitalization and mortality. New human-relevant models of the airways are urgently needed to understand how respiratory infections may trigger asthma attacks and to advance treatment development. Here, we describe a new human-relevant model of rhinovirus-induced asthma exacerbation that recapitulates viral infection of asthmatic airway epithelium and neutrophil transepithelial migration, and enables evaluation of immunomodulatory therapy. Specifically, a microengineered model of fully differentiated human mucociliary airway epithelium was stimulated with IL-13 to induce a T-helper cell type 2 asthmatic phenotype and infected with live human rhinovirus 16 (HRV16) to reproduce key features of viral-induced asthma exacerbation. We observed that the infection with HRV16 replicated key hallmarks of the cytopathology and inflammatory responses observed in human airways. Generation of a T-helper cell type 2 microenvironment through exogenous IL-13 stimulation induced features of asthmatic airways, including goblet cell hyperplasia, reduction of cilia beating frequency, and endothelial activation, but did not alter rhinovirus infectivity or replication. High-resolution kinetic analysis of secreted inflammatory markers revealed that IL-13 treatment altered IL-6, IFN-λ1, and CXCL10 secretion in response to HRV16. Neutrophil transepithelial migration was greatest when viral infection was combined with IL-13 treatment, whereas treatment with MK-7123, a CXCR2 antagonist, reduced neutrophil diapedesis in all conditions. In conclusion, our microengineered Airway Lung-Chip provides a novel human-relevant platform for exploring the complex mechanisms underlying viral-induced asthma exacerbation. Our data suggest that IL-13 may impair the hosts' ability to mount an appropriate and coordinated immune response to rhinovirus infection. We also show that the Airway Lung-Chip can be used to assess the efficacy of modulators of the immune response.


Assuntos
Asma/virologia , Bioengenharia , Progressão da Doença , Dispositivos Lab-On-A-Chip , Pulmão/patologia , Pulmão/virologia , Microtecnologia , Modelos Biológicos , Movimento Celular , Células Cultivadas , Efeito Citopatogênico Viral , Humanos , Infiltração de Neutrófilos , Receptores de Interleucina-8B/antagonistas & inibidores , Receptores de Interleucina-8B/metabolismo , Rhinovirus
10.
J Vis Exp ; (160)2020 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-32628171

RESUMO

Advances in spatial resolution and detection sensitivity of scientific instrumentation make it possible to apply small reactors for biological and chemical research. To meet the demand for high-performance microreactors, we developed a femtoliter droplet array (FemDA) device and exemplified its application in massively parallel cell-free protein synthesis (CFPS) reactions. Over one million uniform droplets were readily generated within a finger-sized area using a two-step oil-sealing protocol. Every droplet was anchored in a femtoliter microchamber composed of a hydrophilic bottom and a hydrophobic sidewall. The hybrid hydrophilic-in-hydrophobic structure and the dedicated sealing oils and surfactants are crucial for stably retaining the femtoliter aqueous solution in the femtoliter space without evaporation loss. The femtoliter configuration and the simple structure of the FemDA device allowed minimal reagent consumption. The uniform dimension of the droplet reactors made large-scale quantitative and time-course measurements convincing and reliable. The FemDA technology correlated the protein yield of the CFPS reaction with the number of DNA molecules in each droplet. We streamlined the procedures about the microfabrication of the device, the formation of the femtoliter droplets, and the acquisition and analysis of the microscopic image data. The detailed protocol with the optimized low running cost makes the FemDA technology accessible to everyone who has standard cleanroom facilities and a conventional fluorescence microscope in their own place.


Assuntos
DNA/química , Microfluídica/métodos , Microtecnologia/instrumentação , Biossíntese de Proteínas , Proteínas/metabolismo , DNA/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Microfluídica/instrumentação , Microscopia de Fluorescência , Água/química
11.
PLoS One ; 15(7): e0236171, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32702047

RESUMO

Cell-substrate adhesion of the social amoeba Dictyostelium discoideum, a model organism often used for the study of chemotaxis, is non-specific and does not involve focal adhesion complexes. Therefore, micropatterned substrates where adherent Dictyostelium cells are constrained to designated microscopic regions are difficult to make. Here we present a micropatterning technique for Dictyostelium cells that relies on coating the substrate with an ∼1µm thick layer of polyethylene glycol (PEG) gel. We show that, when plated on a substrate with narrow parallel stripes of PEG-gel and glass, Dictyostelium cells nearly exclusive adhere to and migrate along the glass stripes, thus providing a model system to study one-dimensional migration of amoeboid cells. Surprisingly, we find substantial differences in the adhesion to PEG-gel and glass stripes between vegetative and developed cells and between two different axenic laboratory strains of Dictyostelium, AX2 and AX4. Even more surprisingly, we find that the distribution of Dictyostelium cells between PEG-gel and glass stripes is significantly affected by the expression of several fluorescent protein markers of the cytoskeleton. We carry out atomic force microscopy based single cell force spectroscopy measurements that confirm that the force of adhesion to PEG-gel substrate can be significantly different between vegetative and developed cells, AX2 and AX4 cells, and cells with and without fluorescent markers. Thus, the choice of parental background, the degree of development, and the expression of fluorescent protein markers can all have a profound effect on cell-substrate adhesion and should be considered when comparing migration of cells and when designing micropatterned substrates.


Assuntos
Movimento Celular , Dictyostelium/citologia , Corantes Fluorescentes/metabolismo , Microtecnologia/métodos , Polietilenoglicóis/farmacologia , Adesão Celular/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Dictyostelium/efeitos dos fármacos , Géis/farmacologia , Análise Espectral
12.
Int J Nanomedicine ; 15: 4105-4123, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32606667

RESUMO

Background: Magnetic nanoparticles (MNPs) hold promise for enhancing delivery of therapeutic agents, either through direct binding or by functioning as miniature propellers. Fluid-filled conduits and reservoirs within the body offer avenues for MNP-enhanced drug delivery. MNP clusters can be rotated and moved across surfaces at clinically relevant distances in response to a rotating magnet. Limited data are available regarding issues affecting MNP delivery by this mechanism, such as adhesion to a cellular wall. Research reported here was initiated to better understand the fundamental principles important for successful implementation of rotational magnetic drug targeting (rMDT). Methods: Translational movements of four different iron oxide MNPs were tested, in response to rotation (3 Hz) of a neodymium-boron-iron permanent magnet. MNP clusters moved along biomimetic channels of a custom-made acrylic tray, by surface walking. The effects of different distances and cellular coatings on MNP velocity were analyzed using videography. Dyes (as drug surrogates) and the drug etoposide were transported by rotating MNPs along channels over a 10 cm distance. Results: MNP translational velocities could be predicted from magnetic separation times. Changes in distance or orientation from the magnet produced alterations in MNP velocities. Mean velocities of the fastest MNPs over HeLa, U251, U87, and E297 cells were 0.24 ± 0.02, 0.26 ± 0.02, 0.28 ± 0.01, and 0.18 ± 0.03 cm/sec, respectively. U138 cells showed marked MNP adherence and an 87.1% velocity reduction at 5.5 cm along the channel. Dye delivery helped visualize the effects of MNPs as microdevices for drug delivery. Dye delivery by MNP clusters was 21.7 times faster than by diffusion. MNPs successfully accelerated etoposide delivery, with retention of chemotherapeutic effect. Conclusion: The in vitro system described here facilitates side-by-side comparisons of drug delivery by rotating MNP clusters, on a human scale. Such microdevices have the potential for augmenting drug delivery in a variety of clinical settings, as proposed.


Assuntos
Sistemas de Liberação de Medicamentos/instrumentação , Nanopartículas de Magnetita/química , Microtecnologia/instrumentação , Rotação , Transporte Biológico , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Difusão , Etoposídeo/farmacologia , Humanos , Microesferas , Tamanho da Partícula , Tomografia Computadorizada por Raios X
13.
Proc Natl Acad Sci U S A ; 117(26): 14667-14675, 2020 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-32532923

RESUMO

Many natural materials possess built-in structural variation, endowing them with superior performance. However, it is challenging to realize programmable structural variation in self-assembled synthetic materials since self-assembly processes usually generate uniform and ordered structures. Here, we report the formation of asymmetric microribbons composed of directionally self-assembled two-dimensional nanoflakes in a polymeric matrix during three-dimensional direct-ink printing. The printed ribbons with embedded structural variations show site-specific variance in their mechanical properties. Remarkably, the ribbons can spontaneously transform into ultrastretchable springs with controllable helical architecture upon stimulation. Such springs also exhibit superior nanoscale transport behavior as nanofluidic ionic conductors under even ultralarge tensile strains (>1,000%). Furthermore, to show possible real-world uses of such materials, we demonstrate in vivo neural recording and stimulation using such springs in a bullfrog animal model. Thus, such springs can be used as neural electrodes compatible with soft and dynamic biological tissues.


Assuntos
Neuroestimuladores Implantáveis , Microtecnologia/instrumentação , Nanoestruturas , Impressão Tridimensional , Animais , Anuros , Elasticidade , Grafite/química , Íons/química , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Neurofisiologia/instrumentação , Nervo Isquiático/fisiologia
14.
Sci Rep ; 10(1): 9248, 2020 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-32514084

RESUMO

Micro-optical coherence tomography (µOCT) is a novel imaging approach enabling visualization of the microstructures of biological tissues at a cellular or sub-cellular level. However, it has been challenging to develop a miniaturized flexible endoscopic µOCT probe allowing helical luminal scanning. In this study, we built a flexible endoscopic µOCT probe with an outer diameter of 1.2 mm, which acquires three-dimensional images of the arterial microstructures via helical scanning with an axial and lateral resolutions of 1.83 µm and 3.38 µm in air, respectively. Furthermore, the depth of focus of the µOCT imaging probe was extended two-fold using a binary phase spatial filter. We demonstrated that the present endoscopic µOCT could image cellular level features of a rabbit artery with high-risk atheroma and a bioresorbable scaffold-implanted swine coronary artery. This highly-translatable endoscopic µOCT will be a useful tool for investigating coronary artery disease and stent biology.


Assuntos
Artérias/diagnóstico por imagem , Vasos Coronários/diagnóstico por imagem , Endoscopia , Fenômenos Mecânicos , Microtecnologia/métodos , Tomografia de Coerência Óptica/métodos , Animais , Artérias/citologia , Calcinose/complicações , Vasos Coronários/citologia , Placa Aterosclerótica/complicações , Placa Aterosclerótica/diagnóstico por imagem , Coelhos , Risco , Suínos
15.
J Vis Exp ; (159)2020 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-32478723

RESUMO

In single molecule fluorescence enzymology, background fluorescence from labeled substrates in solution often limits fluorophore concentration to pico- to nanomolar ranges, several orders of magnitude less than many physiological ligand concentrations. Optical nanostructures called zero mode waveguides (ZMWs), which are 100-200 nm in diameter apertures fabricated in a thin conducting metal such as aluminum or gold, allow imaging of individual molecules at micromolar concentrations of fluorophores by confining visible light excitation to zeptoliter effective volumes. However, the need for expensive and specialized nanofabrication equipment has precluded the widespread use of ZMWs. Typically, nanostructures such as ZMWs are obtained by direct writing using electron beam lithography, which is sequential and slow. Here, colloidal, or nanosphere, lithography is used as an alternative strategy to create nanometer-scale masks for waveguide fabrication. This report describes the approach in detail, with practical considerations for each phase. The method allows thousands of aluminum or gold ZMWs to be made in parallel, with final waveguide diameters and depths of 100-200 nm. Only common lab equipment and a thermal evaporator for metal deposition are required. By making ZMWs more accessible to the biochemical community, this method can facilitate the study of molecular processes at cellular concentrations and rates.


Assuntos
Microscopia de Fluorescência , Microtecnologia/métodos , Nanoestruturas/química , Imagem Individual de Molécula , Alumínio/química , Coloides/química , Cobre/química , Cristalização , Análise de Elementos Finitos , Transferência Ressonante de Energia de Fluorescência , Corantes Fluorescentes/química , Ouro/química , Microesferas , Poliestirenos/química , Porosidade
16.
Pan Afr Med J ; 35(Suppl 1): 3, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32373254

RESUMO

The African Region is committed to measles elimination by 2020 but coverage with the first dose of measles-containing vaccine was only 70% in 2017. Several obstacles to achieving high coverage with measles and rubella vaccines exist, some of which could be overcome with new vaccine delivery technologies. Microarray array patches (MAPs) are single-dose devices used for transcutaneous administration of molecules, including inactivated or attenuated vaccines, that penetrate the outer stratum corneum of the skin, delivering antigens to the epidermis or dermis. MAPs to deliver measles and rubella vaccines have the potential to be a transformative technology to achieve elimination goals in the African Region. MAPs for measles and rubella vaccination have been shown to be safe, immunogenic and thermostable in preclinical studies but results of clinical studies in humans have not yet been published. This review summarizes the current state of knowledge of measles and rubella MAPs, their potential advantages for immunization programs in the African Region, and some of the challenges that must be overcome before measles and rubella MAPs are available for widespread use.


Assuntos
Vacina contra Sarampo/administração & dosagem , Sarampo/prevenção & controle , Vacina contra Rubéola/administração & dosagem , Rubéola (Sarampo Alemão)/prevenção & controle , Adesivo Transdérmico , Cobertura Vacinal/métodos , Administração Cutânea , África/epidemiologia , Humanos , Programas de Imunização/métodos , Microtecnologia/instrumentação , Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos , Cobertura Vacinal/estatística & dados numéricos
17.
PLoS One ; 15(5): e0232518, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32433673

RESUMO

Patterned cell culturing is one of the most useful techniques for understanding the interaction between geometric conditions surrounding cells and their behaviors. The authors previously proposed a simple method for cell patterning with an agarose gel microstructure fabricated by microcasting with a degassed polydimethylsiloxane (PDMS) mold. Although the vacuum pressure produced from the degassed PDMS can drive a highly viscous agarose solution, the influence of solution viscosity on the casting process is unknown. This study investigated the influences of micro-channel dimensions or solution viscosity on the flow of the solution in a micro-channel of a PDMS mold by both experiments and numerical simulation. It was found experimentally that the degassed PDMS mold was able to drive a solution with a viscosity under 575 mPa·s. A simulation model was developed which can well estimate the flow rate in various dimensions of micro-channels. Cross-linked albumin has low viscosity (1 mPa·s) in aqueous solution and can undergo a one-way dehydration process from solution to solid that produces cellular repellency after dehydration. A microstructure of cross-linked albumin was fabricated on a cell culture dish by the microcasting method. After cells were seeded and cultivated on the cell culture dish with the microstructure for 7 days, the cellular pattern of mouse skeletal myoblast cell line C2C12 was observed. The microcasting with cross-linked albumin solution enables preparation of patterned cell culture systems more quickly in comparison with the previous agarose gel casting, which requires a gelation process before the dehydration process.


Assuntos
Técnicas de Cultura de Células/métodos , Albuminas , Animais , Dimetilpolisiloxanos , Camundongos , Microtecnologia/métodos , Mioblastos , Sefarose
18.
Sensors (Basel) ; 20(8)2020 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-32295102

RESUMO

This paper presents a micromachining process for lithium niobate (LiNbO3) material for the rapid prototyping of a resonant sensor design for medical devices applications. Laser micromachining was used to fabricate samples of lithium niobate material. A qualitative visual check of the surface was performed using scanning electron microscopy. The surface roughness was quantitatively investigated using an optical surface profiler. A surface roughness of 0.526 µm was achieved by laser micromachining. The performance of the laser-micromachined sensor has been examined in different working environments and different modes of operation. The sensor exhibits a Quality-factor (Q-factor) of 646 in a vacuum; and a Q-factor of 222 in air. The good match between the modelling and experimental results shows that the laser-micromachined sensor has a high potential to be used as a resonance biosensor.


Assuntos
Técnicas Biossensoriais/métodos , Microtecnologia , Nióbio/química , Óxidos/química , Técnicas Biossensoriais/instrumentação , Lasers , Microscopia Eletrônica de Varredura
19.
PLoS One ; 15(4): e0230713, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32267845

RESUMO

PURPOSE: To evaluate the surgical technique for subretinal implantation of two sizes of PRIMA photovoltaic wireless microchip in two animal models, and refine these surgical procedures for human trials. METHODS: Cats and Macaca fascicularis primates with healthy retina underwent vitrectomy surgery and were implanted with subretinal wireless photovoltaic microchip at the macula/central retina. The 1.5mm PRIMA chip was initially studied in feline eyes. PRIMA implant (2mm,1.5mm sizes) arrays were studied in primates. Feasibility of subretinal chip implantation was evaluated with a newly-developed surgical technique, with surgical complications and adverse events recorded. RESULTS: The 1.5mm implant was placed in the central retina of 11 feline eyes, with implantation duration 43-106 days. The 1.5mm implant was correctly positioned into central macula of 11 primate eyes, with follow-up periods of minimum 6 weeks (n = 11), 2 years (n = 2), and one eye for 3 years. One primate eye underwent multi-chip 1.5mm implantation using two 1.5mm chips. The 2mm implant was delivered to 4 primate eyes. Optical coherence tomography confirmed correct surgical placement of photovoltaic arrays in the subretinal space in all 26 eyes. Intraoperative complications in primate eyes included retinal tear, macular hole, retinal detachment, and vitreous hemorrhage that resolved spontaneously. Postoperatively, there was no case of significant ocular inflammation in the 1.5mm implant group. CONCLUSIONS: We report subretinal implantation of 1.5mm and 2mm photovoltaic arrays in the central retina of feline and central macula of primate eyes with a low rate of device-related complications. The in vivo PRIMA implantation technique has been developed and refined for use for a 2mm PRIMA implant in ongoing human trials.


Assuntos
Microtecnologia/instrumentação , Próteses e Implantes , Retina/cirurgia , Tecnologia sem Fio , Animais , Gatos , Macaca fascicularis , Segurança
20.
PLoS One ; 15(4): e0230679, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32282802

RESUMO

Cell migration on microlanes represents a suitable and simple platform for the exploration of the molecular mechanisms underlying cell cytoskeleton dynamics. Here, we report on the quasi-periodic movement of cells confined in stripe-shaped microlanes. We observe persistent polarized cell shapes and directed pole-to-pole motion within the microlanes. Cells depolarize at one end of a given microlane, followed by delayed repolarization towards the opposite end. We analyze cell motility via the spatial velocity distribution, the velocity frequency spectrum and the reversal time as a measure for depolarization and spontaneous repolarization of cells at the microlane ends. The frequent encounters of a boundary in the stripe geometry provides a robust framework for quantitative investigations of the cytoskeleton protrusion and repolarization dynamics. In a first advance to rigorously test physical models of cell migration, we find that the statistics of the cell migration is recapitulated by a Cellular Potts model with a minimal description of cytoskeleton dynamics. Using LifeAct-GFP transfected cells and microlanes with differently shaped ends, we show that the local deformation of the leading cell edge in response to the tip geometry can locally either amplify or quench actin polymerization, while leaving the average reversal times unaffected.


Assuntos
Movimento Celular , Microtecnologia , Linhagem Celular Tumoral , Citoesqueleto/metabolismo , Humanos , Análise de Célula Única
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