RESUMEN
Electromagnetic tracking (EMT) can benefit image-guided interventions in cases where line of sight is unavailable. However, EMT can suffer from electromagnetic distortion in the presence of metal instruments. Metal instruments are widely used in laparoscopic surgery, ENT surgery, arthroscopy and many other clinical applications. In this work, we investigate the feasibility of tracking such metal instruments by placing the inductive sensor within the instrument shaft. We propose a magnetostatic model of the field within the instrument, and verify the results experimentally for frequencies from 6 kHz to 60 kHz. The impact of the instrument's dimensions, conductivity and transmitting field frequency is quantified for ranges representative of typical metal instruments used in image-guided interventions. We then performed tracking using the open-source Anser EMT system and quantify the error caused by the presence of the rod as a function of the frequency of the eight emitting coils for the system. The work clearly demonstrates why smaller tool diameters (less than 8 mm) are less susceptible to distortion, as well as identifying optimal frequencies (1 kHz to 2 kHz) for transmitter design to minimise for distortion in larger instruments.
Asunto(s)
Metales , Metales/química , Humanos , Cirugía Asistida por Computador/métodos , Cirugía Asistida por Computador/instrumentación , Magnetismo/instrumentación , Diseño de Equipo , Campos ElectromagnéticosRESUMEN
In experiments considering cell handling in microchannels, cell sedimentation in the storage container is a key problem because it affects the reproducibility of the experiments. Here, a simple and low-cost cell mixing device (CMD) is presented; the device is designed to prevent the sedimentation of cells in a syringe during their injection into a microfluidic channel. The CMD is based on a slider crank device made of 3D-printed parts that, combined with a permanent magnet, actuate a stir bar placed into the syringe containing the cells. By using A549 cell lines, the device is characterized in terms of cell viability (higher than 95%) in different mixing conditions, by varying the oscillation frequency and the overall mixing time. Then, a dedicated microfluidic experiment is designed to evaluate the injection frequency of the cells within a microfluidic chip. In the presence of the CMD, a higher number of cells are injected into the microfluidic chip with respect to the static conditions (2.5 times), proving that it contrasts cell sedimentation and allows accurate cell handling. For these reasons, the CMD can be useful in microfluidic experiments involving single-cell analysis.
Asunto(s)
Dispositivos Laboratorio en un Chip , Humanos , Células A549 , Supervivencia Celular , Técnicas Analíticas Microfluídicas/instrumentación , Magnetismo/instrumentación , Separación Celular/instrumentación , Diseño de Equipo , Análisis de la Célula Individual/instrumentaciónRESUMEN
BACKGROUND: The magnetic compression technique has been used to establish an animal model of tracheoesophageal fistula (TEF), but the commonly shaped magnets present limitations of poor homogeneity of TEF and poor model control. We designed a T-shaped magnet system to overcome these problems and verified its effectiveness via animal experiments. AIM: To investigate the effectiveness of a T-shaped magnet system for establishing a TEF model in beagle dogs. METHODS: Twelve beagles were randomly assigned to groups in which magnets of the T-shaped scheme (study group, n = 6) or normal magnets (control group, n = 6) were implanted into the trachea and esophagus separately under gastroscopy. Operation time, operation success rate, and accidental injury were recorded. After operation, the presence and timing of cough and the time of magnet shedding were observed. Dogs in the control group were euthanized after X-ray and gastroscopy to confirm establishment of TEFs after coughing, and gross specimens of TEFs were obtained. Dogs in the study group were euthanized after X-ray and gastroscopy 2 wk after surgery, and gross specimens were obtained. Fistula size was measured in all animals, and then harvested fistula specimens were examined by hematoxylin and eosin (HE) and Masson trichrome staining. RESULTS: The operation success rate was 100% for both groups. Operation time did not differ between the study group (5.25 min ± 1.29 min) and the control group (4.75 min ± 1.70 min; P = 0.331). No bleeding, perforation, or unplanned magnet attraction occurred in any animal during the operation. In the early postoperative period, all dogs ate freely and were generally in good condition. Dogs in the control group had severe cough after drinking water at 6-9 d after surgery. X-ray indicated that the magnets had entered the stomach, and gastroscopy showed TEF formation. Gross specimens of TEFs from the control group showed the formation of fistulas with a diameter of 4.94 mm ± 1.29 mm (range, 3.52-6.56 mm). HE and Masson trichrome staining showed scar tissue formation and hierarchical structural disorder at the fistulas. Dogs in the study group did not exhibit obvious coughing after surgery. X-ray examination 2 wk after surgery indicated fixed magnet positioning, and gastroscopy showed no change in magnet positioning. The magnets were removed using a snare under endoscopy, and TEF was observed. Gross specimens showed well-formed fistulas with a diameter of 6.11 mm ± 0.16 mm (range, 5.92-6.36 mm), which exceeded that in the control group (P < 0.001). Scar formation was observed on the internal surface of fistulas by HE and Masson trichrome staining, and the structure was more regular than that in the control group. CONCLUSION: Use of the modified T-shaped magnet scheme is safe and feasible for establishing TEF and can achieve a more stable and uniform fistula size compared with ordinary magnets. Most importantly, this model offers better controllability, which improves the flexibility of follow-up studies.
Asunto(s)
Modelos Animales de Enfermedad , Imanes , Tráquea , Fístula Traqueoesofágica , Animales , Perros , Fístula Traqueoesofágica/cirugía , Fístula Traqueoesofágica/patología , Fístula Traqueoesofágica/etiología , Tráquea/cirugía , Tráquea/patología , Esófago/cirugía , Esófago/patología , Esófago/diagnóstico por imagen , Gastroscopía/instrumentación , Gastroscopía/métodos , Tempo Operativo , Masculino , Magnetismo/instrumentación , Diseño de Equipo , HumanosRESUMEN
BACKGROUND: We report a new real-time navigation system for laparoscopic hepatectomy (LH), which resembles a car navigation system. MATERIAL AND METHODS: Virtual three-dimensional liver and body images were reconstructed using the "New-VES" system, which worked as roadmap during surgery. Several points of the patient's body were registered in virtual images using a magnetic position sensor (MPS). A magnetic transmitter, corresponding to an artificial satellite, was placed about 40 cm above the patient's body. Another MPS, corresponding to a GPS antenna, was fixed on the handling part of the laparoscope. Fiducial registration error (FRE, an error between real and virtual lengths) was utilized to evaluate the accuracy of this system. RESULTS: Twenty-one patients underwent LH with this system. Mean FRE of the initial five patients was 17.7 mm. Mean FRE of eight patients in whom MDCT was taken using radiological markers for registration of body parts as first improvement, was reduced to 10.2 mm (p = .014). As second improvement, a new MPS as an intraoperative body position sensor was fixed on the right-sided chest wall for automatic correction of postural gap. The preoperative and postoperative mean FREs of 8 patients with both improvements were 11.1 mm and 10.1 mm (p = .250). CONCLUSIONS: Our system may provide a promising option that virtually guides LH.
Asunto(s)
Hepatectomía , Laparoscopía , Humanos , Hepatectomía/métodos , Hepatectomía/instrumentación , Laparoscopía/métodos , Laparoscopía/instrumentación , Femenino , Masculino , Persona de Mediana Edad , Anciano , Imagenología Tridimensional , Neoplasias Hepáticas/cirugía , Sistemas de Navegación Quirúrgica , Adulto , Magnetismo/instrumentación , Cirugía Asistida por Computador/métodosRESUMEN
The separation and purification of biomacromolecules such as nucleic acid is a perpetual topic in separation processes and bioengineering (fine chemicals, biopharmaceutical engineering, diagnostics, and biological characterization). In principle, the solid-phase extraction for nucleic acid exhibits efficient phase separation, low pollution risk, and small sample demand, compared to the conventional liquid-phase extraction. Herein, solid-phase extraction methods are systematically reviewed to outline research progress and explore additional solid-phase sorbents and devices for novel, flexible, and high-efficiency nucleic acid separation processes. The functional materials capture nucleic acid, magnetic and magnetic-free solid-phase extraction methods, separation device design and optimization, and high-throughput automatable applications based on high-performance solid-phase extraction are summarized. Finally, the current challenges and promising topics are discussed.
Asunto(s)
Ácidos Nucleicos/aislamiento & purificación , Extracción en Fase Sólida/métodos , Adsorción , Magnetismo/instrumentación , Magnetismo/métodos , Ácidos Nucleicos/genética , Extracción en Fase Sólida/instrumentaciónRESUMEN
BACKGROUND: Data comparing remote magnetic catheter navigation (RMN) with manual catheter navigation (MCN) ablation of atrial fibrillation (AF) is lacking. The aim of the present prospective observational study was to compare the outcome of RMN versus (vs.) MCN ablation of AF with regards to AF recurrence. METHODS: The study comprised 667 consecutive patients with a total of 939 procedures: 287 patients were ablated using RMN, 380 using MCN. RESULTS: There was no significant difference between the groups at baseline. After 2.3 ± 2.3 years of follow-up, 23% of the patients in the MCN group remained free of AF recurrence compared to 13% in the RMN group (p < .001). After analysis of 299 repeat ablations (133 MCN, 166 RMN) there was a significantly higher reconnection rate of pulmonary veins after RMN ablation p < .001). In multivariable Cox-regression analysis, RMN ablation was an independent risk factor for AF recurrence besides age, persistent AF, number of isolated pulmonary veins, and left atrial diameter. Procedure time, radiofrequency application time and total number of ablation points were higher in the RMN group. Total fluoroscopy time and total fluoroscopy dose were significantly lower for RMN. Complication rates did not differ between groups (p = .842), although the incidence of significant pericardial effusion was higher in the MCN group (seven cases vs. three in RMN group). CONCLUSIONS: In our study the AF recurrence rate and pulmonary vein reconnection rate is higher after RMN ablation with a similar complication rate but reduced probability of pericardial effusion when compared to MCN.
Asunto(s)
Fibrilación Atrial/cirugía , Ablación por Catéter/métodos , Magnetismo/instrumentación , Femenino , Fluoroscopía , Humanos , Masculino , Persona de Mediana Edad , Complicaciones Posoperatorias , Estudios Prospectivos , Recurrencia , Reoperación/estadística & datos numéricos , Factores de RiesgoRESUMEN
The aim of the work was to design and construct a microscopic stage that enables the observation of biological cells in a magnetic field with a constant magnetic force. Regarding the requirements for biological observations in the magnetic field, construction was based on the standard automatic stage of an optical microscope ZEISS Axio Observer, and the main challenge was to design a set of magnets which were the source of a field in which the magnetic force was constant in the observation zone. Another challenge was to design a magnet arrangement producing a weak magnetic field to manipulate the cells without harming them. The Halbach array of magnets was constructed using permanent cubic neodymium magnets mounted on a 3D printed polymer ring. Four sets of magnets were used, differing in their dimensions, namely, 20, 15, 12, and 10 mm. The polymer rings were designed to resist magnetic forces and to keep their shape undisturbed when working under biological conditions. To check the usability of the constructs, experiments with magnetic microparticles were executed. Magnetic microparticles were placed under the microscope and their movement was observed to find the acting magnetic force.
Asunto(s)
Campos Magnéticos , Magnetismo/instrumentación , Supervivencia Celular , Diseño de Equipo , Imagenología Tridimensional , Impresión Tridimensional , Reproducibilidad de los Resultados , TemperaturaRESUMEN
Consumption of leafy greens and to a lesser extent fresh herbs has been associated with several foodborne outbreaks including human norovirus (HuNoV). However, the extraction and detection of viruses from these matrices present multiple challenges such as low recovery yields and relatively high PCR inhibition. A new magnetic silica bead based (MSB) extraction protocol was developed and used to recover norovirus from leafy greens and fresh herbs. The performance results were compared to the ISO 15216-1:2017 standard. The HuNoV GII.4 and GI.5 recovery yields from spiked lettuce using the MSB extraction protocol range from 33 to 82%. There was a good correlation between murine norovirus (MNV) and HuNoV recovery yields from fresh herbs and leafy greens. No reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR) inhibition was detected from leafy green extracts using the MSB methodology. The selected commercial RT-qPCR detection kit had a major impact on RT-qPCR inhibition levels detected in the ISO 15216-1:2017 RNA extracts. RNase treatment was used to estimate genome recovery from HuNoV with intact capsids. This treatment resulted in similar HuNoV and MNV recovery yields. Between 2019 and 2020, the MSB protocol was used to conduct a survey of HuNoV in domestic and imported leafy greens and fresh herbs sold at retail in Canada. All of the 280 samples tested were negative. Overall, the use of MSB was shown to be an efficient approach to recover HuNoV from leafy greens and certain types of fresh herbs and to conduct surveys.
Asunto(s)
Lactuca/virología , Magnetismo/métodos , Norovirus/aislamiento & purificación , Dióxido de Silicio/química , Especias/virología , Animales , Canadá , Contaminación de Alimentos/análisis , Humanos , Fenómenos Magnéticos , Magnetismo/instrumentación , Norovirus/química , Norovirus/genética , Hojas de la Planta/virología , Reacción en Cadena en Tiempo Real de la PolimerasaRESUMEN
High-precision delivery of microrobots at the whole-body scale is of considerable importance for efforts toward targeted therapeutic intervention. However, vision-based control of microrobots, to deep and narrow spaces inside the body, remains a challenge. Here, we report a soft and resilient magnetic cell microrobot with high biocompatibility that can interface with the human body and adapt to the complex surroundings while navigating inside the body. We achieve time-efficient delivery of soft microrobots using an integrated platform called endoscopy-assisted magnetic actuation with dual imaging system (EMADIS). EMADIS enables rapid deployment across multiple organ/tissue barriers at the whole-body scale and high-precision delivery of soft and biohybrid microrobots in real time to tiny regions with depth up to meter scale through natural orifice, which are commonly inaccessible and even invisible by conventional endoscope and medical robots. The precise delivery of magnetic stem cell spheroid microrobots (MSCSMs) by the EMADIS transesophageal into the bile duct with a total distance of about 100 centimeters can be completed within 8 minutes. The integration strategy offers a full clinical imaging technique-based therapeutic/intervention system, which broadens the accessibility of hitherto hard-to-access regions, by means of soft microrobots.
Asunto(s)
Sistemas de Liberación de Medicamentos/instrumentación , Endoscopía/instrumentación , Robótica/instrumentación , Células 3T3 , Animales , Sistemas de Computación , Diagnóstico por Imagen/instrumentación , Diseño de Equipo , Femenino , Humanos , Magnetismo/instrumentación , Masculino , Ratones , Microscopía Electrónica de Rastreo , Microtecnología , Cirugía Endoscópica por Orificios Naturales/instrumentación , Ratas , Ratas Sprague-Dawley , Esferoides Celulares/trasplante , Sus scrofa , UltrasonografíaRESUMEN
In this work, a green strategy was developed to prepare molecularly imprinted polymers functionalized magnetic carbon nanotubes in aqueous phase under mild conditions for cyclic adenosine monophosphate. Thanks to water solubility of chitosan, a natural polysaccharide which is rich in amino and hydroxyl groups, provided the feasibility to synthesize the green molecularly imprinted polymers for water soluble template in aqueous media. Coupled with high-performance liquid chromatography, the method exhibited a short equilibrium time (6 min), high adsorption capacity (22.42 µg/mg), high magnetic susceptibility, and good selectivity to template molecule with the imprinting factor of 2.94. A good linearity in the range of 0.020-3.0 mg/mL for target was obtained with a correlation coefficient of 0.9998. The limit of detection (signal-to-noise ratio = 3) and limit of quantitation (signal-to-noise ratio = 10) of the magnetic solid phase extraction method for cyclic adenosine monophosphate were 5 and 15 ng/mg, respectively. And the practical application of chitosan-based molecularly imprinted polymers as adsorbent to isolate and determine cyclic adenosine monophosphate in real natural samples (winter jujube) was demonstrated.
Asunto(s)
Adenosina Monofosfato/aislamiento & purificación , Magnetismo/métodos , Polímeros Impresos Molecularmente/química , Extractos Vegetales/aislamiento & purificación , Extracción en Fase Sólida/métodos , Ziziphus/química , Adenosina Monofosfato/análisis , Adsorción , Cromatografía Líquida de Alta Presión , Frutas/química , Interacciones Hidrofóbicas e Hidrofílicas , Magnetismo/instrumentación , Impresión Molecular , Polímeros Impresos Molecularmente/síntesis química , Nanotubos de Carbono/química , Extractos Vegetales/análisis , Extracción en Fase Sólida/instrumentaciónRESUMEN
The enumeration of circulating tumor cells (CTCs) in the peripheral bloodstream of metastatic cancer patients has contributed to improvements in prognosis and therapeutics. There have been numerous approaches to capture and counting of CTCs. However, CTCs have potential information beyond simple enumeration and hold promise as a liquid biopsy for cancer and a pathway for personalized cancer therapy by detecting the subset of CTCs having the highest metastatic potential. There is evidence that epithelial cell adhesion molecule (EpCAM) expression level distinguishes these highly metastatic CTCs. The few previous approaches to selective CTC capture according to EpCAM expression level are reviewed. A new two-stage microfluidic device for separation, enrichment and release of CTCs into subpopulations sorted by EpCAM expression level is presented here. It relies upon immunospecific magnetic nanoparticle labeling of CTCs followed by their field- and flow-based separation in the first stage and capture as discrete subpopulations in the second stage. To fine tune the separation, the magnetic field profile across the first stage microfluidic channel may be modified by bonding small Vanadium Permendur strips to its outer walls. Mathematical modeling of magnetic fields and fluid flows supports the soundness of the design.
Asunto(s)
Separación Celular/instrumentación , Molécula de Adhesión Celular Epitelial/metabolismo , Dispositivos Laboratorio en un Chip , Magnetismo/instrumentación , Células Neoplásicas Circulantes , Línea Celular Tumoral , Humanos , Análisis de Secuencia por Matrices de Oligonucleótidos , Unión ProteicaRESUMEN
Epigenetics, such as the dynamic interplay between DNA methylation and demethylation, play diverse roles in critical cellular events. Enzymatic activity at CpG sites, where cytosines are methylated or demethylated, is known to be influenced by the density of CpGs, methylation states, and the flanking sequences of a CpG site. However, how the relevant enzymes are recruited to and recognize their target DNA is less clear. Moreover, although DNA-binding epigenetic enzymes are ideal targets for therapeutic intervention, these targets have been rarely exploited. Single-molecule techniques offer excellent capabilities to probe site-specific protein-DNA interactions and unravel the dynamics. Here, we develop a single-molecule approach that allows multiplexed profiling of protein-DNA complexes using magnetic tweezers. When a DNA hairpin with multiple binding sites is unzipping, strand separation pauses at the positions bound by a protein. We can thus measure site-specific binding probabilities and dissociation time directly. Taking the TET1 CXXC domain as an example, we show that TET1 CXXC binds multiple CpG motifs with various flanking nucleotides or different methylation patterns in an AT-rich DNA. We are able to establish for the first time, at nanometer resolution, that TET1 CXXC prefers G/C flanked CpG motif over C/G, A/T, or T/A flanked ones. CpG methylation strengthens TET1 CXXC recruitment but has little effect on dissociation time. Finally, we demonstrate that TET1 CXXC can distinguish five CpG clusters in a CpG island with crowded binding motifs. We anticipate that the feasibility of single-molecule multiplexed profiling assays will contribute to the understanding of protein-DNA interactions.
Asunto(s)
Metilación de ADN/genética , Proteínas de Unión al ADN/genética , Oxigenasas de Función Mixta/genética , Complejos Multiproteicos/genética , Proteínas Proto-Oncogénicas/genética , Sitios de Unión/genética , Islas de CpG/genética , Desmetilación del ADN , Proteínas de Unión al ADN/aislamiento & purificación , Epigénesis Genética/genética , Humanos , Magnetismo/instrumentación , Oxigenasas de Función Mixta/química , Complejos Multiproteicos/aislamiento & purificación , Proteínas Proto-Oncogénicas/química , Imagen Individual de MoléculaRESUMEN
The use of nano- and microparticles as a release system for agrochemicals has been increasing in agricultural sector. However, the production of eco-friendly and smart carriers that can be easily handled in the environment is still a challenge for this technology. In this context, we have developed a biodegradable release system for the herbicide atrazine with magnetic properties. Herein, we investigated the (a) physicochemical properties of the atrazine-loaded magnetic poly(ε-caprolactone) microparticles (MPs:ATZ), (b) in vitro release kinetic profile of the herbicide, and (c) phytotoxicity toward photosynthesis in the aquatic fern Azolla caroliniana. The encapsulation efficiency of the herbicide in the MPs:ATZ was ca. 69%, yielding spherical microparticles with a diameter of ca. 100 µm, a sustained-release profile, and easily manipulated with an external magnetic field. Also, phytotoxicity issues showed that the MPs:ATZ maintained their herbicidal activity via inhibition of PSII, showing lower toxicity compared with the nonencapsulated ATZ at 0.01 and 0.02 µmol·L-1. Therefore, this technology may conveniently promote a novel magnetic controlled release of the herbicide ATZ (with the potential to be collected from a watercourse) and act as a nutrient boost to the nontarget plant, with good herbicidal activity and reduced risk to the environment.
Asunto(s)
Sistemas de Liberación de Medicamentos/métodos , Herbicidas/química , Magnetismo/métodos , Complejo de Proteína del Fotosistema II/antagonistas & inhibidores , Poliésteres/química , Atrazina/química , Sistemas de Liberación de Medicamentos/instrumentación , Liberación de Fármacos , Helechos/efectos de los fármacos , Helechos/metabolismo , Herbicidas/farmacología , Magnetismo/instrumentación , Nanopartículas/química , Fotosíntesis/efectos de los fármacos , Complejo de Proteína del Fotosistema II/metabolismo , Poliésteres/farmacologíaRESUMEN
Magnetic nanostructures and nanomaterials play essential roles in modern bio medicine and technology. Proper surface functionalization of nanoparticles (NPs) allows the selective bonding thus application of magnetic forces to a vast range of cellular structures and biomolecules. However, the spherical geometry of NPs poises a series of limitations in various potential applications. Mostly, typical spherical core shell structure consists of magnetic and non-magnetic layers have little tunability in terms of magnetic responses, and their single surface functionality also limits chemical activity and selectivity. In comparison to spherical NPs, nanowires (NWs) possess more degrees of freedom in achieving magnetic and surface chemical tenability. In addition to adjustment of magnetic anisotropy and inter-layer interactions, another important feature of NWs is their ability to combine diï¬erent components along their length, which can result in diverse bio-magnetic applications. Magnetic NWs have become the candidate material for biomedical applications owing to their high magnetization, cheapness and cost effective synthesis. With large magnetic moment, anisotropy, biocompatibility and low toxicity, magnetic NWs have been recently used in living cell manipulation, magnetic cell separation and magnetic hyperthermia. In this review, the basic concepts of magnetic characteristics of nanoscale objects and the influences of aspect ratio, composition and diameter on magnetic properties of NWs are addressed. Some underpinning physical principles of magnetic hyperthermia (MH), magnetic resonance imaging (MRI) and magnetic separation (MS) have been discussed. Finally, recent studies on magnetic NWs for the applications in MH, MRI and MS were discussed in detail.
Asunto(s)
Hipertermia Inducida/métodos , Imagen por Resonancia Magnética/métodos , Imanes/análisis , Nanotecnología/métodos , Nanocables/análisis , Animales , Medios de Contraste/análisis , Diseño de Equipo , Humanos , Hipertermia Inducida/instrumentación , Imagen por Resonancia Magnética/instrumentación , Magnetismo/instrumentación , Magnetismo/métodos , Nanotecnología/instrumentación , Nanocables/ultraestructuraRESUMEN
A magnetic porous organic framework (M-POF) was rationally designed and served as a sorbent for magnetic solid-phase extraction of six nitroimidazoles from chicken meat prior to their assay by high-performance liquid chromatography with diode array detection. The M-POF exhibited good magnetic responsiveness and outstanding affinity to nitroimidazoles with large adsorption capacity up to 36 mg g-1. Under optimal conditions, the developed method offered good linearity (r greater than 0.992) in the range of 1.5-100.0 ng g-1, low limits of detection (S/N = 3) of 0.5-0.8 ng g-1, low limits of quantification of 1.5-2.5 ng g-1 and high enrichment factors of 80-175 for the nitroimidazoles. The method was successfully applied to analyze nitroimidazoles in chicken meat. The recoveries were 80.2-118% with relative standard deviations lower than 12%. The adsorption mechanism was further explored and the results showed that the M-POF exhibited adsorption potential for compounds with strong polar interactions.
Asunto(s)
Antibacterianos/aislamiento & purificación , Contaminación de Alimentos/análisis , Magnetismo/métodos , Carne/análisis , Estructuras Metalorgánicas/química , Nitroimidazoles/aislamiento & purificación , Extracción en Fase Sólida/métodos , Adsorción , Animales , Antibacterianos/análisis , Bioensayo , Pollos , Cromatografía Líquida de Alta Presión , Límite de Detección , Magnetismo/instrumentación , Músculo Esquelético/química , Nitroimidazoles/análisis , Porosidad , Extracción en Fase Sólida/instrumentaciónRESUMEN
Circle-to-circle amplification (C2CA) is a specific and precise cascade nucleic acid amplification method consisting of more than one round of padlock probe ligation and rolling circle amplification (RCA). Although C2CA provides a high amplification efficiency with a negligible increase of false-positive risk, it contains several step-by-step operation processes. We herein demonstrate a homogeneous and isothermal nucleic acid quantification strategy based on C2CA and optomagnetic analysis of magnetic nanoparticle (MNP) assembly. The proposed homogeneous circle-to-circle amplification eliminates the need for additional monomerization and ligation steps after the first round of RCA, and combines two amplification rounds in a one-pot reaction. The second round of RCA produces amplicon coils that anneal to detection probes grafted onto MNPs, resulting in MNP assembly that can be detected in real-time using an optomagnetic sensor. The proposed methodology was applied for the detection of a synthetic complementary DNA of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2, also known as 2019-nCoV) RdRp (RNA-dependent RNA polymerase) coding sequence, achieving a detection limit of 0.4 fM with a dynamic detection range of 3 orders of magnitude and a total assay time of ca. 100 min. A mathematical model was set up and validated to predict the assay performance. Moreover, the proposed method was specific to distinguish SARS-CoV and SARS-CoV-2 sequences with high similarity.
Asunto(s)
Betacoronavirus/aislamiento & purificación , Técnicas Biosensibles/instrumentación , Infecciones por Coronavirus/diagnóstico , ADN Complementario/análisis , Técnicas de Amplificación de Ácido Nucleico/instrumentación , Neumonía Viral/diagnóstico , Técnicas Biosensibles/métodos , COVID-19 , Diseño de Equipo , Estudios de Factibilidad , Humanos , Límite de Detección , Magnetismo/instrumentación , Magnetismo/métodos , Nanopartículas de Magnetita/química , Técnicas de Amplificación de Ácido Nucleico/métodos , Pandemias , SARS-CoV-2RESUMEN
Screening of pathogenic bacteria plays a crucial role in preventing foodborne disease outbreaks. In this study, an ultrasensitive biosensor was developed for fast detection of Salmonella using self-assembled magnetic nanoparticle (MNP) chains for continuous-flow separation of Salmonella from large-volume sample, urease coated gold nanoparticles (GNPs) for specific labelling of Salmonella and efficient amplification of signal, and linear scan voltammetry for sensitive detection of catalysate. First, MNP chains were formed and distributed in a 3D spiral channel using mutually repelling cylindrical magnets and ring iron gears to control anti-Salmonella monoclonal antibody coated MNPs. After bacterial sample was continuous-flow drawn into the channel, bacteria-MNP complexes (magnetic bacteria) were formed on the chains, resulting in specific separation of target bacteria from sample background. Then, anti-Salmonella polyclonal antibodies and urease coated GNPs were drawn to label the magnetic bacteria, resulting in the formation of enzymatic bacteria. After washing to remove residual GNPs, urea was drawn and catalyzed by urease on enzymatic bacteria, resulting in the produce of catalysate (ammonium carbonate). Finally, the catalysate was transferred into a microfluidic chip with a thin-film Ag/AgCl reference electrode array for linear scan voltammetric measurement, and the resistance of catalysate was obtained to determine the amount of target bacteria. This biosensor could quantitatively detect Salmonella from 1.0 × 101 to 1.0 × 106 CFU/mL in 1 h with low detection limit of 101 CFU/mL. The mean recovery for Salmonella in spiked milk was about 104.3%.
Asunto(s)
Técnicas Biosensibles/instrumentación , Magnetismo/instrumentación , Leche/microbiología , Salmonella/aislamiento & purificación , Ureasa/química , Animales , Anticuerpos Inmovilizados/química , Electrodos , Enzimas Inmovilizadas/química , Diseño de Equipo , Contaminación de Alimentos/análisis , Oro/química , Límite de Detección , Fenómenos Magnéticos , Nanopartículas del Metal/química , Infecciones por Salmonella/microbiología , Salmonella typhimurium/aislamiento & purificación , Plata/químicaRESUMEN
The identification and analysis of endogenous phosphopeptides is still a scientific challenge due to their low abundance and the complicated matrix of bio-samples. Hence, the highly effective enrichment of endogenous phosphopeptides is a prerequisite for comprehensive phosphoproteome analysis. Here, a novel guanidyl-functionalized magnetic covalent organic framework (denoted as SPIO@COF-Guanidyl) nanosphere was designed for selective and efficient phosphopeptide enrichment. The SPIO@COF-Guanidyl nanospheres possessed specific recognition sites of functional guanidyl groups, large surface area, regular mesoporous structure, and superior magnetic responsiveness, resulting in excellent performances in phosphopeptide enrichment with high selectivity (ß-casein/BSA = 1:1000), extremely high sensitivity (5 × 10-11 M), an excellent size-exclusion effect (ß-casein digests/ß-casein/bovine serum albumin (BSA) = 1:500:500), and good reusability (at least 5 times). In addition, due to the synergistic effect of functional molecules and the size-selection effect of the COF structure, SPIO@COF-Guanidyl nanospheres captured 63 unique endogenous phosphopeptides from a 10 µL sample of human saliva. Therefore, SPIO@COF-Guanidyl nanospheres possess a huge potential for trace biological detection and endogenous phosphopeptide analysis.
Asunto(s)
Magnetismo/métodos , Estructuras Metalorgánicas/química , Fosfopéptidos/aislamiento & purificación , Animales , Bovinos , Humanos , Hígado/química , Magnetismo/instrumentación , Leche/química , Nanosferas/química , Tamaño de la Partícula , Porosidad , Ratas , Saliva/químicaRESUMEN
A highly efficient and selective method was successfully developed by using magnetic molecularly imprinted polymers (MMIPs) combined with high performance liquid chromatography (HPLC) to quickly determine patulin (PAT) in juice. MMIPs was prepared by surface imprinting method using Fe3O4 nanoparticles as supporter, 2-oxindole as virtual template, (3-Aminopropyl) triethoxysilane (APTES) as functional monomer and tetraethyl orthosilicate (TEOS) as crosslinking agent. The structure of the product was characterized by vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results showed that MMIP with a particle size of about 450 nm was successfully prepared, the imprinted molecular layer accounted for about 11.6% of the total mass, and the saturation magnetization was about 6.82 emu/g. The maximum adsorption capacities (Qmax) of kinetic and thermodynamic adsorption experiments were 1.97 mg/g and 4.241 mg/g, respectively. The adsorption process was highly selective and fitted well with the pseudo-second-order model. Langmuir model demonstrated that the binding sites were evenly distributed on the surface of the MMIPs. Scatchard analysis showed that MMIPs had two types of binding sites with Qmax of 4.53 mg/g and 5.73 mg/g, respectively. In the actual sample application, the limit of detection (LOD) and the limit of quantification (LOQ) were 3 µg/kg and 10 µg/kg. And the recovery rate of the sample was 86.44-95.50%. MMIPs possessed excellent applicability with stability of 1.11-3.16% and accuracy of 0.63-1.94%. These results indicated that MMIPs had good performance in separating PAT and was suitable for determining PAT in actual samples.
Asunto(s)
Jugos de Frutas y Vegetales/análisis , Magnetismo/métodos , Polímeros Impresos Molecularmente/química , Patulina/aislamiento & purificación , Extracción en Fase Sólida/métodos , Adsorción , Cromatografía Líquida de Alta Presión , Contaminación de Alimentos/análisis , Magnetismo/instrumentación , Nanopartículas de Magnetita/química , Patulina/química , Extracción en Fase Sólida/instrumentación , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
Newly developed magnetic carbon particles prepared from coffee grounds were used as the sorbent for the magnetic solid-phase extraction of eight phthalic acid esters (PAEs) from plastic bottled water prior to their analysis by GC-MS. The method, which uses coffee-ground particles coated with iron oxide, was validated, and exhibited linearities for the eight PAEs, with coefficients of determination above 0.998 in the 0.005 to 0.1 mg/L concentration range. Limits of detection and limits of quantification of 0.00003 to 0.002 mg/L and 0.0001 to 0.005 mg/L, respectively, were achieved, with recoveries (%) ranging between 77% and 120%, and relative standard deviations for intra- and interday precisions below 16.3% at three fortification levels. No PAE residues were detected when the developed and validated method was applied to 10 real plastic bottled water samples. Taken together, the developed magnetic solid-phase extraction method is a useful tool for monitoring phthalate esters in aqueous samples. PRACTICAL APPLICATION: The development of a new, inexpensive, and efficient magnetic sorption material derived from spent coffee grounds, and its ability to determine phthalate esters in aqueous solutions was described by GC-MS/MS. The developed magnetic solid-phase extraction method is a useful tool for monitoring phthalate esters in aqueous samples.