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The self-assembly system of the rod-shaped tobacco mosaic virus (TMV) has been studied extensively for nanoscale applications. TMV coat protein assembly is modulated by intersubunit carboxylate groups whose electrostatic repulsion limits the assembly of virus rods without incorporating genomic RNA. To engineer assembly control into this system, we reprogrammed intersubunit carboxylate interactions to produce self-assembling coat proteins in the absence of RNA and in response to unique pH and ionic environmental conditions. Specifically, engineering a charge attraction at the intersubunit E50-D77 carboxylate group through a D77K substitution stabilized the coat proteins assembly into virus-like rods. In contrast, the reciprocal E50K modification alone did not confer virus-like rod assembly. However, a combination of R46G/E50K/E97G substitutions enabled virus-like rod assembly. Interestingly, the D77K substitution displays a unique pH-dependent assembly-disassembly profile, while the R46G/E50K/E97G substitutions confer a novel salt concentration dependency for assembly control. In addition, these unique environmentally controlled coat proteins allow for the directed assembly and disassembly of chimeric virus-like rods both in solution and on substrate-attached seed rods. Combined, these findings provide a controllable means to assemble functionally discrete virus-like rods for use in nanotechnology applications.
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Nanotubos , Vírus do Mosaico do Tabaco , Proteínas do Capsídeo/genética , RNA Viral , Vírus do Mosaico do Tabaco/genética , Montagem de VírusRESUMO
In this work, we introduce an electrowetting-assisted 3-D biofabrication process allowing both complete and localized functionalization of bionanoreceptors onto densely arranged 3-D microstructures. The integration of biomaterials with 3-D microdevice components offers exciting opportunities for communities developing miniature bioelectronics with enhanced performance and advanced modes of operation. However, most biological materials are stable only in properly conditioned aqueous solutions, thus the water-repellent properties exhibited by densely arranged micro/nanostructures (widely known as the Cassie-Baxter state) represent a significant challenge to biomaterial integration. Here, we first investigate such potential limitations using cysteine-modified tobacco mosaic virus (TMV1cys) as a model bionanoreceptor and a set of Au-coated Si-micropillar arrays (µPAs) of varying densities. Furthermore, we introduce a novel biofabrication system adopting electrowetting principles for the controlled localization of TMV1cys bionanoreptors on densely arranged µPAs. Contact angle analysis and SEM characterizations provide clear evidence to indicate structural hydrophobicity as a key limiting factor for 3-D biofunctionalization and for electrowetting as an effective method to overcome this limitation. The successful 3-D biofabrication is confirmed using SEM and fluorescence microscopy that show spatially controlled and uniform assemblies of TMV1cys on µPAs. The increased density of TMV1cys per device footprint produces a 7-fold increase in fluorescence intensity attributed to the µPAs when compared to similar assemblies on planar substrates. Combined, this work demonstrates the potential of electrowetting as a unique enabling solution for the controlled and efficient biofabrication of 3-D-patterned micro/nanodomains.
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Oxidative stress is implicated in many diseases yet no simple, rapid, and robust measurement is available at the point-of-care to assist clinicians in detecting oxidative stress. Here, we report results from a discovery-based research approach in which a redox mediator is used to probe serum samples for chemical information relevant to oxidative stress. Specifically, we use an iridium salt (K2IrCl6) to probe serum for reducing activities that can transfer electrons to iridium and thus generate detectable optical and electrochemical signals. We show that this Ir-reducing assay can detect various biological reductants and is especially sensitive to glutathione (GSH) compared to alternative assays. We performed an initial clinical evaluation using serum from 10 people diagnosed with schizophrenia, a mental health disorder that is increasingly linked to oxidative stress. The measured Ir-reducing capacity was able to discriminate people with schizophrenia from healthy controls (p < 0.005), and correlations were observed between Ir-reducing capacity and independent measures of symptom severity.
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Cloretos/química , Irídio/química , Estresse Oxidativo , Área Sob a Curva , Técnicas Eletroquímicas , Glutationa/química , Humanos , Oxirredução , Curva ROC , Esquizofrenia/diagnóstico , Esquizofrenia/metabolismo , Compostos de Sulfidrila/sangue , Compostos de Sulfidrila/químicaRESUMO
This paper reports the implementation of temporal capillary microfluidic patterns and biological nanoscaffolds in autonomous microfabrication of nanostructured symmetric electrochemical supercapacitors. A photoresist layer was first patterned on the substrate, forming a capillary microfluidics layer with two separated interdigitated microchannels. Tobacco mosaic virus (TMV) macromolecules suspended in solution are autonomously delivered into the microfluidics, and form a dense bio-nanoscaffolds layer within an hour. This TMV layer is utilized in the electroless plating and thermal oxidation for creating nanostructured NiO supercapacitor. The galvanostatic charge/discharge cycle showed a 3.6-fold increase in areal capacitance for the nanostructured electrode compared to planar structures. The rapid creation of nanostructure-textured microdevices with only simple photolithography and bionanostructure self-assembly can completely eliminate the needs for sophisticated synthesis or deposition processes. This method will contribute to rapid prototyping of wide range of nano-/micro-devices with enhanced performance.
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Nanoestruturas/química , Vírus do Mosaico do Tabaco/química , Capacitância Elétrica , Eletrodos , Substâncias Macromoleculares/química , Microfluídica/métodos , Propriedades de SuperfícieRESUMO
We investigate gold, TiN, and platinum in combination with a chitosan-catechol-based redox-cycling system (RCS) for electrochemical detection of the antipsychotic clozapine. We have previously demonstrated the RCS for detection of clozapine in serum, but challenges remain regarding low signal-to-noise ratios. This can be mitigated by selection of electrode materials with beneficial surface morphologies and/or compositions. We employ cyclic voltammetry to assess the redox current generated by clozapine, and differentiate solely surface-area-based effects from clozapine-specific ones using a standard redox couple. We find that nano- and microstructured platinum greatly amplifies the clozapine signal compared to gold (up to 1490-fold for platinum black). However, the material performs poorly in the presence of chloride ions, and RCS modification provides no further amplification. The RCS combined with atomic-layer-deposited (ALD) TiN, on the other hand, increases the signal by 7.54 times, versus 2.86 times for RCS on gold, with a 9.2-fold lower variability, indicating that the homogenous and chemically inert properties of ALD-TiN may make it an ideal electrode material.
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Bacterial biofilms are a common cause of chronic medical implant infections. Treatment and eradication of biofilms by conventional antibiotic therapy has major drawbacks including toxicity and side effects associated with high-dosage antibiotics. Additionally, administration of high doses of antibiotics may facilitate the emergence of antibiotic resistant bacteria. Thus, there is an urgent need for the development of treatments that are not based on conventional antibiotic therapies. Presented herein is a novel bacterial biofilm combination treatment independent of traditional antibiotics, by using low electric fields in combination with small molecule inhibitors of bacterial quorum sensing - autoinducer-2 analogs. We investigate the effect of this treatment on mature Escherichia coli biofilms by application of an alternating and offset electric potential in combination with the small molecule inhibitor for 24 h using both macro and micro-scale devices. Crystal violet staining of the macro-scale biofilms shows a 46 % decrease in biomass compared to the untreated control. We demonstrate enhanced treatment efficacy of the combination therapy using a high-throughput polydimethylsiloxane-based microfluidic biofilm analysis platform. This microfluidic flow cell is designed to reduce the growth variance of in vitro biofilms while providing an integrated control, and thus allows for a more reliable comparison and evaluation of new biofilm treatments on a single device. We utilize linear array charge-coupled devices to perform real-time tracking of biomass by monitoring changes in optical density. End-point confocal microscopy measurements of biofilms treated with the autoinducer analog and electric fields in the microfluidic device show a 78 % decrease in average biofilm thickness in comparison to the negative controls and demonstrate good correlation with real-time optical density measurements. Additionally, the combination treatment showed 76 % better treatment efficacy compared to conventional antibiotic therapy. Taken together these results suggest that the antibiotic-free combination treatment described here may provide an effective alternative to traditional antibiotic therapies against bacterial biofilm infections. Use of this combination treatment in the medical and environmental fields would alleviate side effects associated with high-dosage antibiotic therapies, and reduce the rise of antibiotic-resistant bacteria.
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Biofilmes/efeitos dos fármacos , Eletricidade , Escherichia coli/efeitos dos fármacos , Escherichia coli/fisiologia , Homosserina/análogos & derivados , Lactonas/química , Lactonas/farmacologia , Escherichia coli/citologia , Homosserina/química , Homosserina/farmacologia , Dispositivos Lab-On-A-Chip , Microscopia Confocal , Percepção de Quorum/efeitos dos fármacosRESUMO
This work presents a thorough electrochemical and reliability analysis of a sensing scheme for the antipsychotic clozapine. We have previously demonstrated a novel detection approach for this redox-active drug, highly effective in schizophrenia treatment, based on a catechol-modified chitosan film. The biomaterial film enables amplification of the oxidative current generated by clozapine through redox cycling. Here, we study critical electrochemical and material aspects of the redox cycling system to overcome barriers in point-of-care monitoring in complex biological samples. Specifically, we explore the electrochemical parameter space, showing that enhanced sensing performance depends on the presence of a reducing mediator as well as the electrochemical technique applied. These factors account for up to 1.75-fold and 2.47-fold signal enhancement, respectively. Looking at potential interferents, we illustrate that the redox cycling system allows for differentiation between selected redox-active species, clozapine's structurally largely analogous metabolite norclozapine as well as the representative catecholamine dopamine. Furthermore, we investigate material stability and fouling with reuse as well as storage. We find no evidence of film fouling due to clozapine; slow overall biomaterial degradation with successive use accounts for a 2.2% absolute signal loss and can be controlled for. Storage of the redox cycling system appears feasible over weeks when kept in solution with only 0.26%/day clozapine signal degradation, while ambient air exposure of three or more days reduces performance by 58%. This study not only advances our understanding of the catechol-modified chitosan system, but also further establishes the viability of applying it toward sensing clozapine in a clinical setting. Such point-of-care monitoring will allow for broader use of clozapine by increasing convenience to patients as well as medical professionals, thus improving the lives of people affected by schizophrenia through personalized medicine.
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Catecóis/química , Quitosana/química , Clozapina/química , Eletroquímica/métodosRESUMO
Dopamine (DA) and serotonin (5-HT) are neurotransmitters that regulate a wide range of physiological and behavioral processes. Monitoring of both neurotransmitters with real-time analysis offers important insight into the mechanisms that shape animal behavior. However, bioelectronic tools to simultaneously monitor DA and 5-HT interactive dynamics in freely moving animals are underdeveloped. This is mainly due to the limited sensor sensitivity with miniaturized electronics. Here, we present a semi-implantable electrochemical device achieved by integrating a multi-surface-modified carbon fiber microelectrode with a miniaturized potentiostat module to detect DA and 5-HT in vivo with high sensitivity and selectivity. Specifically, carbon fiber microelectrodes were modified through electrochemical treatment and surface coatings to improve sensitivity, selectivity, and antifouling properties. A customized, lightweight potentiostat module was developed for untethered electrochemical measurements. Integrated with the microelectrode, the microsystem is compact (2.8 × 2.3 × 2.1 cm) to minimize its impacts on animal behavior and achieved simultaneous detection of DA and 5-HT with sensitivities of 48.4 and 133.0 nA/µM, respectively, within submicromolar ranges. The system was attached to the crayfish dorsal carapace, allowing electrode implantation into the heart of a crayfish to monitor DA and 5-HT dynamics, followed by drug injections. The semi-implantable biosensor system displayed a significant increase in oxidation peak currents after DA and 5-HT injections. The device successfully demonstrated the application for in vivo simultaneous monitoring of DA and 5-HT in the hemolymph (i.e., blood) of freely behaving crayfish underwater, yielding a valuable experimental tool to expand our understanding of the comodulation of DA and 5-HT.
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Astacoidea , Dopamina , Técnicas Eletroquímicas , Microeletrodos , Serotonina , Animais , Dopamina/análise , Serotonina/análise , Técnicas Eletroquímicas/métodos , Técnicas Eletroquímicas/instrumentação , Tecnologia sem Fio , Fibra de Carbono/química , Técnicas Biossensoriais/métodosRESUMO
Hydrogen sulfide (H2 S) is a gaseous inflammatory mediator and important signaling molecule for maintaining gastrointestinal (GI) homeostasis. Excess intraluminal H2 S in the GI tract has been implicated in inflammatory bowel disease and neurodegenerative disorders; however, the role of H2 S in disease pathogenesis and progression is unclear. Herein, an electrochemical gas-sensing ingestible capsule is developed to enable real-time, wireless amperometric measurement of H2 S in GI conditions. A gold (Au) three-electrode sensor is modified with a Nafion solid-polymer electrolyte (Nafion-Au) to enhance selectivity toward H2 S in humid environments. The Nafion-Au sensor-integrated capsule shows a linear current response in H2 S concentration ranging from 0.21 to 4.5 ppm (R2 = 0.954) with a normalized sensitivity of 12.4% ppm-1 when evaluated in a benchtop setting. The sensor proves highly selective toward H2 S in the presence of known interferent gases, such as hydrogen (H2 ), with a selectivity ratio of H2 S:H2 = 1340, as well as toward methane (CH4 ) and carbon dioxide (CO2 ). The packaged capsule demonstrates reliable wireless communication through abdominal tissue analogues, comparable to GI dielectric properties. Also, an assessment of sensor drift and threshold-based notification is investigated, showing potential for in vivo application. Thus, the developed H2 S capsule platform provides an analytical tool to uncover the complex biology-modulating effects of intraluminal H2 S.
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Polímeros de Fluorcarboneto , Hidrogênio , Polímeros de Fluorcarboneto/química , Trato Gastrointestinal , Dióxido de CarbonoRESUMO
Uniform dimensions and genetic tractability make filamentous viruses attractive templates for the display of functional groups used in materials science, sensor applications, and vaccine development. However, active virus replication and recombination often limit the usefulness of these viruses for such applications. To circumvent these limitations, genetic modifications of selected negatively charged intersubunit carboxylate residues within the coat protein of tobacco mosaic virus (TMV) were neutralized so as to stabilize the assembly of rod-shaped virus-like particles (VLPs) within bacterial expression systems. Here we show that TMV-VLP nanorods are easily purified, stable, and can be programmed in a variety of configurations to display functional peptides for antibody and small molecule binding.
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Proteínas do Capsídeo/química , Nanotubos de Peptídeos/química , Sequência de Aminoácidos , Substituição de Aminoácidos , Proteínas do Capsídeo/genética , Ácidos Carboxílicos/química , Escherichia coli , Dados de Sequência Molecular , Nanotubos de Peptídeos/ultraestrutura , Fragmentos de Peptídeos/química , Multimerização Proteica , Vírus do Mosaico do Tabaco/química , Vírion/químicaRESUMO
Quorum sensing (QS), the process of autoinducer-mediated cell-cell signaling among bacteria, facilitates biofilm formation, virulence, and many other multicellular phenotypes. QS inhibitors are being investigated as antimicrobials because of their potential to reduce symptoms of infectious disease while slowing the emergence of resistant strains. Autoinducer-2 (AI-2) analogs have been shown to inhibit genotypic QS responses among many bacteria. We demonstrate for the first time, the ability of C1-alkyl AI-2 analog, isobutyl-DPD, to significantly inhibit the maturation of Escherichia coli biofilms grown in vitro. Using a novel microfluidic device that incorporates dynamic, real-time measurements of biofilm density, we also show that a combinatorial approach wherein isobutyl-DPD ((S)-4,5-dihydroxy-2,3-pentanedione) is used with the antibiotic gentamicin is quite effective in rendering near complete clearance of pre-existing E. coli biofilms. Similarly, another AI-2 analog, phenyl-DPD, also used in combination with near MIC levels of gentamicin, resulted in clearance of preformed Pseudomonas aeruginosa biofilms. Clearance of pre-existing biofilms has remained a significant health care challenge; these results warrant consideration of a new approach based on the combination of "quenching" QS signal transduction processes with traditional antibiotic treatment.
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Antibacterianos/metabolismo , Biofilmes/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Escherichia coli/fisiologia , Homosserina/análogos & derivados , Lactonas/metabolismo , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/fisiologia , Biofilmes/crescimento & desenvolvimento , Escherichia coli/crescimento & desenvolvimento , Gentamicinas/metabolismo , Homosserina/metabolismo , Pseudomonas aeruginosa/crescimento & desenvolvimentoRESUMO
Serotonin (5-HT) is a neurotransmitter involved in many biophysiological processes in the brain and in the gastrointestinal tract. Electrochemical methods are commonly used to quantify 5-HT, but their reliability may suffer due to the time-dependent nature of adsorption-limited 5-HT detection, as well as electrode fouling over repeated measurements. Mathematical characterization and modeling of adsorption-based electrochemical signal generation would improve reliability of 5-HT measurement. Here, a model was developed to track 5-HT electrode adsorption and resulting current output by combining Langmuir adsorption kinetic equations and adsorption-limited electrochemical equations. 5-HT adsorption binding parameters were experimentally determined at a carbon-nanotube coated Au electrode: KD = 7 × 10-7 M, kon = 130 M-1 s-1, koff = 9.1 × 10-5 s-1. A computational model of 5-HT adsorption was then constructed, which could effectively predict 5-HT fouling over 50 measurements (R2 = 0.9947), as well as predict electrode responses over varying concentrations and measurement times. The model aided in optimizing the measurement of 5-HT secreted from a model enterochromaffin cell line-RIN14B-minimizing measurement time. The presented model simplified and improved the characterization of 5-HT detection at the selected electrode. This could be applied to many other adsorption-limited electrochemical analytes and electrode types, contributing to the improvement of application-specific modeling and optimization processes.
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Serotonin (5-HT) is one of the key neurotransmitters in the human body, regulating numerous physiological functions. A disruption in 5-HT homeostasis could result in serious health problems, including neurodegenerative disorders, depression, and 5-HT syndrome. Detection of 5-HT concentrations in biological fluids, such as urine, is a potential solution for early diagnosis of these diseases. In this study, we developed a novel, simple, and low-cost electrochemical sensing platform consisting of a portable workstation with customized electrodes for 5-HT detection in artificial biological fluids. Nafion/carbon nanotubes (CNTs) and electrochemically modified carbon fiber microelectrodes (Nafion-CNT/EC CFMEs) displayed improved 5-HT sensitivity and selectivity. Together with a customized Ag/AgCl reference electrode and Pt counter electrode, the portable 5-HT sensing platform had a sensitivity of 0.074 µA µM-1 and a limit of detection (LOD) of 140 nM. This system was also assessed to measure 5-HT spiked in artificial urine samples, showing nearly full recovery rates. These satisfactory results demonstrated that the portable system exhibits outstanding performance and confirmed the feasibility of 5-HT detection, which can be used to provide point-of-care analysis in actual biological samples.
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Nanotubos de Carbono , Serotonina , Humanos , Microeletrodos , Fibra de CarbonoRESUMO
Ingestible capsules have the potential to become an attractive alternative to traditional means of treating and detecting gastrointestinal (GI) disease. As device complexity increases, so too does the demand for more effective capsule packaging technologies to elegantly target specific GI locations. While pH-responsive coatings have been traditionally used for the passive targeting of specific GI regions, their application is limited due to the geometric restrictions imposed by standard coating methods. Dip, pan, and spray coating methods only enable the protection of microscale unsupported openings against the harsh GI environment. However, some emerging technologies have millimeter-scale components for performing functions such as sensing and drug delivery. To this end, we present the freestanding region-responsive bilayer (FRRB), a packaging technology for ingestible capsules that can be readily applied for various functional ingestible capsule components. The bilayer is composed of rigid polyethylene glycol (PEG) under a flexible pH-responsive Eudragit® FL 30 D 55, which protects the contents of the capsule until it arrives in the targeted intestinal environment. The FRRB can be fabricated in a multitude of shapes that facilitate various functional packaging mechanisms, some of which are demonstrated here. In this paper, we characterize and validate the use of this technology in a simulated intestinal environment, confirming that the FRRB can be tuned for small intestinal release. We also show a case example where the FRRB is used to protect and expose a thermomechanical actuator for targeted drug delivery.
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We present a unique microfluidic platform to allow for quick and sensitive probing of protein adsorption to various functionalized surfaces. The ability to tailor a sensor surface for a specific analyte is crucial for the successful application of portable gas and fluid sensors and is of great interest to the drug screening community. However, choosing the correct surface chemistry to successfully passivate against nonspecific binding typically requires repeated trial and error experiments. The presented device incorporates an array of integrated electrochemical sensors for fast, sensitive, label-free detection of these binding interactions. The layout of the electrodes allows for loading various surface chemistries in one direction while sensing their interactions with particular compounds in another without any cross-contamination. Impedance data is collected for three commonly used passivation compounds (mercaptohexanol, polyethylene glycol, and bovine serum albumin) and demonstrates their interaction with three commonly studied proteins in genetic and cancer research (cAMP receptor protein, tumor necrosis factor α, and tumor necrosis factor ß). The ability to quickly characterize various surface interactions provides knowledge for selecting optimal functionalization for any biosensor.
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Proteína Receptora de AMP Cíclico/metabolismo , Técnicas Eletroquímicas/métodos , Linfotoxina-alfa/metabolismo , Técnicas Analíticas Microfluídicas/métodos , Soroalbumina Bovina/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Animais , Técnicas Biossensoriais/métodos , Bovinos , Proteína Receptora de AMP Cíclico/química , Eletrodos , Linfotoxina-alfa/química , Técnicas Analíticas Microfluídicas/instrumentação , Polietilenoglicóis/química , Mapeamento de Interação de Proteínas , Soroalbumina Bovina/química , Propriedades de Superfície , Fator de Necrose Tumoral alfa/químicaRESUMO
GOAL: This work introduces an integrated system incorporated seamlessly with a commercial Foley urinary catheter for bacterial growth sensing and biofilm treatment. METHODS: The system is comprised of flexible, interdigitated electrodes incorporated with a urinary catheter via a 3D-printed insert for impedance sensing and bioelectric effect-based treatment. Each of the functions were wirelessly controlled using a custom application that provides a user-friendly interface for communicating with a custom PCB via Bluetooth to facilitate implementation in practice. RESULTS: The integrated catheter system maintains the primary functions of indwelling catheters - urine drainage, balloon inflation - while being capable of detecting the growth of Escherichia coli, with an average decrease in impedance of 13.0% after 24 hours, tested in a newly-developed simulated bladder environment. Furthermore, the system enables bioelectric effect-based biofilm reduction, which is performed by applying a low-intensity electric field that increases the susceptibility of biofilm bacteria to antimicrobials, ultimately reducing the required antibiotic dosage. CONCLUSION: Overall, this modified catheter system represents a significant step forward for catheter-associated urinary tract infection (CAUTI) management using device-based approaches, integrating flexible electrodes with an actual Foley catheter along with the control electronics and mobile application. SIGNIFICANCE: CAUTIs, exacerbated by the emergence of antibiotic-resistant pathogens, represent a significant challenge as one of the most prevalent healthcare-acquired infections. These infections are driven by the colonization of indwelling catheters by bacterial biofilms.
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Cateteres de Demora , Cateteres Urinários , Bactérias , Biofilmes , Cateteres de Demora/efeitos adversos , Cateterismo Urinário/efeitos adversos , Cateteres Urinários/efeitos adversosRESUMO
The emergence of bacteria that evade antibiotics has accelerated research on alternative approaches that do not target cell viability. One such approach targets cell-cell communication networks mediated by small molecule signaling. In this report, we assemble biological nanofactories within a bioMEMS device to capture and manipulate the behavior of quorum sensing (QS) bacteria as a step toward modifying small molecule signaling. Biological nanofactories are bio-inspired nanoscale constructs which can include modules with different functionalities, such as cell targeting, molecular sensing, product synthesis, and ultimately self-destruction. The biological nanofactories reported here consist of targeting, sensing, synthesis and, importantly, assembly modules. A bacteria-specific antibody constitutes the targeting module while a genetically engineered fusion protein contains the sensing, synthesis and assembly modules. The nanofactories are assembled on chitosan electrodeposited within a microchannel of the bioMEMS device; they capture QS bacteria in a spatially selective manner and locally synthesize and deliver the "universal" small signaling molecule autoinducer-2 (AI-2) at the captured cell surface. The nanofactory based AI-2 delivery is demonstrated to alter the progression of the native AI-2 based QS response of the captured bacteria. Prospects are envisioned for utilizing our technique as a test-bed for understanding the AI-2 based QS response of bacteria as a means for developing the next generation of antimicrobials.
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Técnicas de Cultura de Células/instrumentação , Separação Celular/instrumentação , Escherichia coli/fisiologia , Sistemas Microeletromecânicos/instrumentação , Técnicas Analíticas Microfluídicas/instrumentação , Micromanipulação/instrumentação , Percepção de Quorum/fisiologia , Bioensaio/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Nanotecnologia/instrumentação , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Ingestible capsule systems continue to evolve to overcome drawbacks associated with traditional gastrointestinal (GI) diagnostic and therapeutic processes, such as limitations on which sections of the GI tract can be accessed or the inability to measure local biomarker concentrations. We report an integrated capsule sensing system, utilizing a hybrid packaging scheme coupled with triglyceride film-coated capacitive sensors, for measuring biochemical species present in the duodenum, such as pancreatic lipase and bile acids. The system uses microfabricated capacitive sensors interfaced with a Bluetooth low-energy (BLE)-microcontroller, allowing wireless connectivity to a mobile app. The triglyceride films insulate the sensor surface and react either with 0.01-1 mM lipase via hydrolysis or 0.07-7% w/v bile acids via emulsification in simulated fluids, leading to measurable changes in capacitance. Cross reactivity of the triglyceride films is evaluated in both phosphate buffered saline (PBS) as well as pancreatic trypsin solutions. The film morphology is observed after exposure to each stimulus to better understand how these changes alter the sensor capacitance. The capsule utilizes a 3D-printed package coated with polymers that remain intact in acid solution (mimicking gastric conditions), then dissolve at a duodenum-mimicking neutral pH for triggered opening of the sensing chamber from which we can subsequently detect the presence of pancreatic lipase. This device strategy represents a significant step towards using embedded packaging and triglyceride-based materials to target specific regions of the GI tract and sensing biochemical contents for evaluating gastrointestinal health.
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Trato Gastrointestinal , Polímeros , Concentração de Íons de Hidrogênio , Estudo de Prova de Conceito , TriglicerídeosRESUMO
Biofilms are the primary cause of clinical bacterial infections and are impervious to typical amounts of antibiotics, necessitating very high doses for elimination. Therefore, it is imperative to have suitable methods for characterization to develop novel methods of treatment that can complement or replace existing approaches using significantly lower doses of antibiotics. This review presents some of the current developments in microsystems for characterization and sensing of bacterial biofilms. Initially, we review current standards for studying biofilms that are based on invasive and destructive end-point biofilm characterization. Additionally, biofilm formation and growth is extremely sensitive to various growth and environmental parameters that cause large variability in biofilms between repeated experiments, making it very difficult to compare experimental repeats and characterize the temporal characteristics of these organisms. To address these challenges, recent developments in the field have moved toward systems and miniature devices that can aid in the non-invasive characterization of bacterial biofilms. Our review focuses on several types of microsystems for biofilm evaluation including optical, electrochemical, and mechanical systems. This review will show how these devices can lead to better understanding of the physiology and function of these communities of bacteria, which can eventually lead to the development of novel treatments that do not rely on high-dosage antibiotics.
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Pseudomonas aeruginosa is a Gram-negative nosocomial pathogen that is a leading cause of morbidity and mortality in cystic fibrosis patients and immunocompromised individuals worldwide. The isolate examined in this study, PA14-UM, is a well-characterized isolate utilized in studies from the University of Maryland.