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1.
Environ Res ; 220: 115192, 2023 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-36587721

RESUMO

This work demonstrates the simultaneous identification of four hazardous heavy metals in water samples, namely copper, lead, cadmium, and mercury. A simple yet selective electrode with the simplest fabrication procedure was used. The modified porous carbon threads coated with gold nanoparticles (AuNPs) was employed as a working electrode. The surface chemistry and morphology of the AuNPs deposited porous carbon thread surface were examined. The electrocatalytic activity of the metals on the Au-modified thread surface was observed using the differential pulse voltammetry (DPV) technique. Furthermore, all four metal ions were detected simultaneously, and no interference was observed. Individual and simultaneous experiments to test the impact of concentration revealed that the limit of detection (LoD) was observed to be 1.126 µM, 1.419 µM, 0.966 µM, 0.736 µM for the Cd2+, Pb2+, Cu2+, and Hg2+ metal ions respectively in a linear concentration range of 10-110 µM of each. Subsequently, the study of pH, interference with coexisting metal ions, repeatability study, and stability analysis was also performed. A real sample analysis utilising three different lake water samples is also carried out to further understand the application of the proposed sensor. A good recovery rate is achieved, and the results are reported. This work paves way for the on-field applicability of the present heavy metal detection platform.


Assuntos
Mercúrio , Nanopartículas Metálicas , Metais Pesados , Ouro , Microeletrodos , Fibra de Carbono , Porosidade , Metais Pesados/análise , Mercúrio/análise , Carbono , Água , Íons
2.
Sensors (Basel) ; 23(23)2023 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-38067687

RESUMO

Antimicrobial resistance (AMR) is a global health threat, progressively emerging as a significant public health issue. Therefore, an antibiotic susceptibility study is a powerful method for combating antimicrobial resistance. Antibiotic susceptibility study collectively helps in evaluating both genotypic and phenotypic resistance. However, current traditional antibiotic susceptibility study methods are time-consuming, laborious, and expensive. Hence, there is a pressing need to develop simple, rapid, miniature, and affordable devices to prevent antimicrobial resistance. Herein, a miniaturized, user-friendly device for the electrochemical antibiotic susceptibility study of Escherichia coli (E. coli) has been developed. In contrast to the traditional methods, the designed device has the rapid sensing ability to screen different antibiotics simultaneously, reducing the overall time of diagnosis. Screen-printed electrodes with integrated miniaturized reservoirs with a thermostat were developed. The designed device proffers simultaneous incubator-free culturing and detects antibiotic susceptibility within 6 h, seven times faster than the conventional method. Four antibiotics, namely amoxicillin-clavulanic acid, ciprofloxacin, ofloxacin, and cefpodoxime, were tested against E. coli. Tap water and synthetic urine samples were also tested for antibiotic susceptibility. The results show that the device could be used for antibiotic resistance susceptibility testing against E. coli with four antibiotics within six hours. The developed rapid, low-cost, user-friendly device will aid in antibiotic screening applications, enable the patient to receive the appropriate treatment, and help to lower the risk of anti-microbial resistance.


Assuntos
Infecções por Escherichia coli , Escherichia coli , Humanos , Testes de Sensibilidade Microbiana , Antibacterianos/farmacologia , Combinação Amoxicilina e Clavulanato de Potássio
3.
Biomed Microdevices ; 23(2): 31, 2021 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-34091727

RESUMO

Undoubtedly, various kinds of nanomaterials are of great significance due to their enormous applications in diverse areas. The structure and productivity of nanomaterials are heavily dependent on the process used for their synthesis. The synthesizing process plays a vital role in shaping nanomaterials effectively for better productivity. The conventional method requires expensive and massive thermal instruments, a huge volume of reagents. This paper aims to develop an Automatic Miniaturized Temperature Controller (AMTC) device for the synthesis of nickel oxide (NiO), copper oxide (CuO) nanoparticles, and nanomicelles. The device features a low-cost, miniaturized, easy-to-operate with plug-and-play power source, precise temperature control, and geotagged real-time data logging facility for the producing nanoparticles. With a temperature accuracy of ± 2 °C, NiO and CuO nanoparticles, and nanomicelles are synthesized on AMTC device, and are subjected to different characterizations to analyze their morphological structure. The obtained mean size of NiO and CuO is 27.14 nm and 85.13 nm respectively. As a proof-of-principle, the synthesized NiO and CuO nanomaterials are validated for electrochemical sensing of dopamine, hydrazine, and uric acid. Furthermore, the study is conducted, wherein, Dexamethasone (Dex) loaded nanomicelles are developed using AMTC device and compared to the conventional thin-film hydration method. Subsequently, as a proof-of-application, the developed nanomicelles are evaluated for transcorneal penetration using exvivo goat cornea model. Ultimately, the proposed device can be utilized for performing a variety of controlled thermal reactions on a minuscule platform with an integrated and miniaturized approach for various applications.


Assuntos
Nanopartículas , Preparações Farmacêuticas , Cobre , Smartphone , Temperatura
4.
Nanotechnology ; 31(42): 425504, 2020 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-32748804

RESUMO

Evidently, microfluidic devices are proven to be one of the most effective and powerful tools for manipulating, preparing, functionalizing and producing new generation nanoparticles and nanocomposites. Their benefits include low solution/sample feeding, excellent handling of reagents, exceptional control of size and composition, compactness, easy to process with rapid thermal management and cost-effectiveness. Such advantages have led to the endorsement of nano-microscale fabrication methods to develop highly controllable and reproducible minuscule devices. This work aims to design and develop a microscale-based temperature control device with added features like low-cost, portability, miniaturized, easy-to-use, minuscule reaction volume and point-of-source system for the synthesis of nanoparticles. The device incorporates many features such as real-time data access with a GUI interface with a smartphone open-source app for Bluetooth and Database cloud for an Internet of Things module. The portable thermal device is then calibrated and is capable of achieving a maximum temperature of 250 °C in 25 min. The fabricated device is harnessed for the synthesis of manganese oxide (MnO2) nanoparticles. The synthesized nanoparticles were subjected to various characterization techniques like SEM and XPS to analyze the surface morphology. To test the applicability, as a proof of concept, the synthesized nanoparticles were tested for electrochemical sensing of hydrogen peroxide and dopamine. Overall, the portable device can be utilized for carrying out diverse temperature-controlled reactions in a microfluidic system in a user-friendly and automated manner.

5.
Analyst ; 2018 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-29546255

RESUMO

Direct sensing of uric acid (UA) in an undiluted whole blood sample is reported here taking human whole blood as an analyte and a self-supporting electrolyte. Among various solid electrodes (Pt, Au, GCE, and GCE/Nafion) and carbon nanomaterials (carbon nanofibers, graphene oxide, graphite nanopowder, graphitized mesoporous carbon (GMC), single-walled carbon nanotubes, and multiwalled carbon nanotubes) tested, a GMC-modified glassy carbon electrode, designated as GCE/GMC, showed a remarkable response towards direct electrochemical oxidation of blood uric acid at ∼0.25 V vs. Ag/AgCl, unlike the poor and/or feeble current signals with the other unmodified and modified electrodes. It is plausible that the mesoporous nature of the GMC favours the formation of a blood-GMC bio-corona through internalization and provides straight access to blood-matrixed uric acid. Furthermore, the effects of the scan rate and interference with various biochemicals on the GCE/GMC were analysed. The electrochemical oxidation reaction is found to be diffusion controlled in nature and there is no interference from common biochemicals like ascorbic acid, glucose, tryptophan, H2O2, xanthine, hypoxanthine, cysteine, nitrate, nitrite, and sulfide in blood. Real blood UA sample analysis was demonstrated with comparable UA analysis results from the clinical measurement.

6.
Analyst ; 141(7): 2145-9, 2016 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-26922940

RESUMO

A highly redox active human whole blood-carbon nanomaterial modified electrode has been developed, which showed a redox peak (vs. Ag/AgCl) similar to that of hemoglobin (vs. Ag/AgCl) in red blood cells. Clinical relevance of this for direct electrochemical analysis of blood hemoglobin content (anemia) and thalassemia disease diagnosis was demonstrated.


Assuntos
Anemia/sangue , Anemia/diagnóstico , Análise Química do Sangue/métodos , Hemoglobinas/análise , Talassemia/sangue , Talassemia/diagnóstico , Adulto , Análise Química do Sangue/instrumentação , Eletroquímica , Eletrodos , Feminino , Humanos , Lactente , Masculino , Nanoestruturas/química , Oxirredução
7.
Artigo em Inglês | MEDLINE | ID: mdl-38963750

RESUMO

The identification of biomarkers has significant benefits for early disease diagnosis and treatment. Hence, there is an increasing demand for low-cost, disposable point-of-care diagnostic devices for rapid and specific biomarker detection, with good sensitivity and range. Interdigitated electrodes (IDEs) are among the most widely used transducers, especially in chemical and biological sensors, because of their high sensitivity, low cost, and straightforward manufacturing procedure. In this work, a simple 3D printed IDE structure has been developed for cardiac troponin I detection to indicate the risk of acute myocardial infarction (AMI). IDEs have been fabricated using 3D printing technique and the electrically conductive composite polylactic acid (PLA) filament being utilized for the fabrication of electrodes. The demonstrated cardiac troponin I sensor has a calculated quantification limit and detection limit of 0.233 ng ml-1 and 76.97 pg ml-1, respectively which are clinically significant ranges for AMI identification. Electrochemical analytical techniques, such as electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), were carried out for the detection of analyte concentration. Furthermore, using this fabrication methodology IDEs can be fabricated for under US$ 0.4 which can be utilized to detect several other biomarkers.

8.
IEEE Trans Nanobioscience ; 23(3): 491-498, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38587943

RESUMO

Microbial Fuel Cells (MFCs) have recently gained attention, as they are inexpensive, green in nature, and sustainable. As per the report, by Allied Market Research the global market size of MFCs will increase from $ 264.8 million in 2021 to $ 452.2 million in 2030, growing at a CAGR of 4.5%. The present work is a comparative study of various types of electrolytes that can be used in MFCs. The working electrodes were printed using conducting graphene-based Polylactic Acid (PLA) filaments with the help of a 3D printer under the principle of the fused deposition method. Simulated electrolytes and natural environmental microbial electrolytes were used here. Also, electrolytes of pure E. coli culture were studied. Lake water reported the highest power density of 8.259 mW/cm2 while Stale E. Coli reported the lowest around 0.184 mW/cm2. The study comprehensively lists potential wastewaters that can fuel the MFCs. With the pioneering of various comparative studies of electrolytes, one can insight into the recruitment of electrolytes with high-performance benchmarks for miniaturized energy storage and other microelectronics applications.


Assuntos
Fontes de Energia Bioelétrica , Eletrodos , Eletrólitos , Escherichia coli , Impressão Tridimensional , Águas Residuárias , Fontes de Energia Bioelétrica/microbiologia , Eletrólitos/química , Águas Residuárias/microbiologia , Águas Residuárias/química , Escherichia coli/metabolismo , Benchmarking , Desenho de Equipamento , Grafite/química
9.
IEEE Trans Nanobioscience ; 23(3): 410-417, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38507383

RESUMO

L-Tyrosine (L-Tyr), a critical amino acid whose aberrant levels impact melanin and dopamine levels in human body while also increasing insulin resistance thereby increasing the risk of type 2 diabetes. The objective of this study was to detect the amount of L-Tyr in human fluids by tailored electrochemical synthesis of well adhered, homogenous and thin molecularly imprinted polymers (MIPs) by the electro-polymerization of pyrrole on glassy carbon electrode modified functionalized multi-walled carbon nanotubes. The key benefits of this procedure over previous imprinting techniques were the elimination of expensive materials like Au and tedious multi-step synthesis, for L-Tyr detection using a handheld potentiostat. The developed particles were characterized using Fourier Transform Infrared Spectroscopy, Scanning Electron Microscope, Chronoamperometry, and Cyclic Voltammetry. With strong reproducibility and stability, this optimized approach provides a rapid and effective method of preparing and sensing MIPs for the target analyte with a broad linear range of [Formula: see text] to [Formula: see text]. The Limit of Detection and Limit of Quantification were [Formula: see text] and [Formula: see text], respectively. The engineered sensor was validated for quantifying the concentrations of L-Tyr in human blood and serum samples, yielding satisfactory recovery and can be expanded in future to detect analytes simultaneous.


Assuntos
Técnicas Eletroquímicas , Polímeros Molecularmente Impressos , Nanotubos de Carbono , Tirosina , Tirosina/química , Tirosina/sangue , Tirosina/análise , Humanos , Técnicas Eletroquímicas/métodos , Polímeros Molecularmente Impressos/química , Nanotubos de Carbono/química , Limite de Detecção , Reprodutibilidade dos Testes , Impressão Molecular/métodos , Polímeros/química
10.
Bioelectrochemistry ; 160: 108795, 2024 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-39146929

RESUMO

E6 and E7 oncogenes are pivotal in the carcinogenic transformation in HPV infections and efficient diagnostic methods can ensure the detection and differentiation of HPV genotype. This study describes the development and validation of an electrochemical, label-free genosensor coupled with a microfluidic system for detecting the E6 and E7 oncogenes in cervical scraping samples. The nanostructuring employed was based on a cysteine and graphene quantum dots layer that provides functional groups, surface area, and interesting electrochemical properties. Biorecognition tests with cervical scraping samples showed differentiation in the voltammetric response. Low-risk HPV exhibited a lower biorecognition response, reflected in ΔI% values of 82.33 % ± 0.29 for HPV06 and 80.65 % ± 0.68 for HPV11 at a dilution of 1:100. Meanwhile, high-risk, HPV16 and HPV18, demonstrated ΔI% values of 96.65 % ± 1.27 and 93 % ± 0.026, respectively, at the same dilution. Therefore, the biorecognition intensity followed the order: HPV16 >HPV18 >HPV06 >HPV11. The limit of detection and the limit of quantification of E6E7 microfluidic LOC-Genosensor was 26 fM, and 79.6 fM. Consequently, the E6E7 biosensor is a valuable alternative for clinical HPV diagnosis, capable of detecting the potential for oncogenic progression even in the early stages of infection.


Assuntos
Técnicas Biossensoriais , Proteínas Oncogênicas Virais , Técnicas Biossensoriais/métodos , Humanos , Proteínas Oncogênicas Virais/genética , Feminino , Limite de Detecção , Proteínas E7 de Papillomavirus/genética , Colo do Útero/virologia , Grafite/química , Infecções por Papillomavirus/diagnóstico , Infecções por Papillomavirus/virologia , Técnicas Eletroquímicas/métodos , Proteínas Repressoras/genética , Técnicas Analíticas Microfluídicas/métodos , Técnicas Analíticas Microfluídicas/instrumentação , Pontos Quânticos/química , Dispositivos Lab-On-A-Chip , Papillomaviridae/genética , Papillomaviridae/isolamento & purificação
11.
IEEE Trans Nanobioscience ; 22(1): 149-154, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-35476572

RESUMO

Snake bite is a serious medical emergency often leading to untimely fatalities. Serotherapy is the only treatment method adapted for this, whose efficacy depends on identification of the Snake species and venom type. As a specific antivenom has to be implicated for saving the victim, in most of the cases, such identification is challenging, thus, leading to mortality due to delay in treatment or side effects of injecting polymeric non-specific antivenom. Therefore, a point-of-care, venom specific detection device could be an impactful diagnostic tool. Herein, a prototype of miniaturized electrochemical sensing platform is presented for detection of Crotaline, venom from various common pit viper snakes. A three electrode based micro-platform with carbon fibre microelectrode, modified with mesoporous carbon, embedded and laminated in commercial OHP sheet, has been developed. The dimensions of the miniaturized platform was 25 mm ×35 mm, size of electrode was 0.5 mm ×25 mm with an electrochemical testing zone of diameter 10 mm, electrode spacing as 3 mm. The microscopic characterization revealed immobilization of porous carbon on fine fibrous structure. The device gave highly stable and sensitive electro-catalytic oxidation of Crotaline at E'= at 0.81 V, and provided a linear range of 50- [Formula: see text], limit of detection as [Formula: see text] and limit of quantification as [Formula: see text]. The device exhibited negligible interference from physiological blood serum biochemicals, high stability and reproducibility. Further, real blood serum samples, analysis via standard addition approach, was performed which showcased appreciable recovery values confirming the practical applicability of the device.


Assuntos
Antivenenos , Venenos de Serpentes , Antivenenos/uso terapêutico , Fibra de Carbono , Microeletrodos , Reprodutibilidade dos Testes , Carbono
12.
Anal Chim Acta ; 1237: 340591, 2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36442949

RESUMO

Bacterial contamination and infection is a major health concern today leading to the significance of its detection. Being lab-based bacterial culturing processes, the present approaches are time consuming and require trained skillset. An economical, and miniaturized lab-on-chip device, capable of simultaneous detection of bacterial growth, could be a benchmarking tool for monitoring the bacterial contamination. Herein, the microfluidic-based electrochemical device for a fast, susceptible, detection of Escherichia coli was developed. The device could aid incubator free bacteria culturing in the ambient atmosphere and simultaneously monitor and detect the growth electrochemically. A three-electrode system, integrated with a reservoir and a portable thermostat temperature controller was fabricated and assembled. To achieve this, three-electrodes were embedded on the microfluidic device by screen-printing carbon paste, and the working electrode was enhanced by graphitized mesoporous carbon. Cyclic voltammetry response was noted as the function of concentration and growth of Escherichia Coli in the reservoir. The device gave a linear bacterial concentration range of 0.336 × 1012 to 40 × 1012 CFU mL-1, detection limit of 0.35 CFU mL-1 and the quantification limit of 1.05 CFU mL-1 which was less than the maximum allowable limit. The developed platform was further used to detect and continuously monitor the bacterial growth in the real sample (mango juice) for a period of 36 h. Finally, the interference from other common bacteria on the electrode selectivity was also investigated. Such approach in being further modified for specific sensing of bacteria in patients suffering from different diseases such as corneal ulcers, Diarrhea, tuberculosis, leprosy, and syphilis.


Assuntos
Infecções por Escherichia coli , Escherichia coli , Humanos , Dispositivos Lab-On-A-Chip , Microfluídica , Carbono
13.
IEEE Trans Nanobioscience ; 22(2): 301-307, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-35788459

RESUMO

Ammonia is one of the most prominent and hazardous water pollutants; hence its selective and sensitive detection in water is crucial for monitoring water quality and determining its usability. In the present work, a simple, cost-effective electrochemical sensor for the detection of ammonia is presented. Multi-walled carbon nanotubes modified ultra-micro-carbon thread electrode (UME/MWCNT) has been realized. The electro-catalytic activity of ammonia is studied by voltammetry and amperometry techniques and the results are presented. The microscopic characterization of UME/MWCNT for surface morphology analysis was also carried out. Further, the UME/MWCNT based electrochemical sensor was tested for its practical application by exploring various parameters like the effect of scan rate, pH and interference from co-existing bio-chemicals like nitrate, nitrite, phosphate, hydrazine, H2 [Formula: see text] uric acid, ascorbic acid and dopamine along with real sample analysis. The developed sensor can efficiently detect ammonia in a linear range of [Formula: see text] to 1 mM which is well within the permissible safe drinking water limit. The limit of detection (LoD) and limit of quantification (LoQ) obtained for the developed sensor were [Formula: see text] and [Formula: see text] respectively. The negligible interference, good reproducibility, and appreciable recovery values indicated the potential of the developed UME for real-time ammonia detection. As a flexible electrode, UME can be further modified and fabricated as a microfluidic or a miniaturized device for a portable electrochemical sensing platform in future.


Assuntos
Amônia , Nanotubos de Carbono , Técnicas Eletroquímicas , Qualidade da Água , Nanotubos de Carbono/química , Reprodutibilidade dos Testes , Eletrodos , Limite de Detecção
14.
IEEE Trans Nanobioscience ; 22(3): 548-553, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36269916

RESUMO

Metabolic biomarkers, such as Dopamine (DA), Uric acid (UA), and Ascorbic acid (AA), have significant roles in determining the physiological functioning of the human body. These are often analyzed through clinical lab-based procedures which are bulky and require skilled technicians. In view of this, the design, development, and fabrication of a portable, cost-effective, user-friendly, and disposable device for electro-analytical detection, leading to point-of-care (POC) detection of these metabolic biomarkers is a pressing need. This work reports a laser-induced reduced graphene oxide (LIrGO) based miniaturized paper device fabricated by laser ablation of a lab-grade paper using a blue diode laser (450 nm). A three-electrode electrochemical platform was designed with the LIrGO electrodes, whereby bare rGO electrodes were employed as working and counter electrodes, and Ag/AgCl ink-coated rGO was used as the reference electrode. The device was characterized morphologically by Scanning Electron Microscopy (SEM) and electrochemically by a potentiostat. The prepared device was subjected to electrochemical sensing of Dopamine (DA), Uric Acid (UA), and Ascorbic Acid (AA). Furthermore, the effects of several sensory parameters, such as concentration, pH, and interference, were analyzed. A linear range of 10- [Formula: see text] was obtained for all three analytes with the limit of detection (LoD) being [Formula: see text], [Formula: see text], [Formula: see text], and the limit of quantification (LoQ) being [Formula: see text], [Formula: see text], [Formula: see text] for DA, UA and AA, respectively. Finally, the device was tested for non-interference with co-analytes and validated by testing a real sample of human blood serum. This work demonstrates a proof-of-principle of utilizing bare LIrGO for selective sensing which will open door to multiplexed and POC sensing.


Assuntos
Dopamina , Grafite , Humanos , Ácido Úrico , Técnicas Eletroquímicas , Grafite/química , Lasers , Eletrodos , Ácido Ascórbico/análise , Ácido Ascórbico/química , Biomarcadores
15.
IEEE Trans Nanobioscience ; 22(4): 881-888, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37022373

RESUMO

This work delves upon developing a two-layer plasma-bonded microfluidic device with a microchannel layer and electrodes for electroanalytical detection of heavy metal ions. The three-electrode system was realized on an ITO-glass slide by suitably etching the ITO layer with the help of CO2 laser. The microchannel layer was fabricated using a PDMS soft-lithography method wherein the mold created by maskless lithography. The optimized dimensions opted to develop a microfluidic device with length of 20 mm, width of 0.5 mm and gap of 1 mm. The device, with bare unmodified ITO electrodes, was tested to detect Cu and Hg by a portable potentiostat connected with a smartphone. The analytes were introduced in the microfluidic device with a peristaltic pump at an optimal flow rate of [Formula: see text]/min. The device exhibited sensitive electro-catalytic sensing of both the metals by achieving an oxidation peak at -0.4 V and 0.1 V for Cu and Hg respectively. Furthermore, square wave voltammetry (SWV) approach was used to analyze the scan rate effect and concentration effect. The device also used to simultaneously detect both the analytes. During simultaneous sensing of Hg and Cu, the linear range was observed between [Formula: see text] to [Formula: see text], the limit of detection (LOD) was found to be [Formula: see text] and [Formula: see text] for Cu and Hg respectively. Further, no interference with other co-existing metal ions was found manifesting the specificity of the device to Cu and Hg. Finally, the device was successfully tested with real samples like tap water, lake water, and serum with remarkable recovery percentages. Such portable devices pave way for detecting various heavy metal ions in a point-of-care environment. The developed device can also be used for detection of other heavy metals like cadmium, lead, zinc etc., by modifying the working electrode with the various nanocomposites.


Assuntos
Mercúrio , Metais Pesados , Cobre , Sistemas Automatizados de Assistência Junto ao Leito , Eletrodos , Água , Dispositivos Lab-On-A-Chip
16.
STAR Protoc ; 4(2): 102327, 2023 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-37243603

RESUMO

Here, we present a protocol for a miniaturized microfluidic device that enables quantitative tracking of bacterial growth. We describe steps for fabricating a screen-printed electrode, a laser-induced graphene heater, and a microfluidic device with its integrations. We then detail the electrochemical detection of bacteria using a microfluidic fuel cell. The laser-induced graphene heater provides the temperature for the bacterial culture, and metabolic activity is recognized using a bacterial fuel cell. Please see Srikanth et al.1 for comprehensive information on the application and execution of this protocol.

17.
IEEE Trans Nanobioscience ; 22(2): 337-344, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-35820008

RESUMO

This work delves upon the development of different types of miniaturized and 3D printed devices having interdigitated electrodes (IDEs) for the detection of Escherichia coli (E. coli) bacteria. The IDEs were fabricated using different approaches including laser-induced graphene (LIG) on polyamide, direct laser writing on glass, and polymeric 3D printing technique, and their suitability for bacteria detection has been compared. The electrochemical impedance spectroscopy (EIS) technique was employed to detect the E. coli bacteria in the prepared miniaturized devices, and the sensory response was compared. EIS was performed in the frequency range between 1 Hz to 1 MHz to record the bacterial growth and activities as a function of change in electrical impedance, and detection performance of the different miniaturized devices with IDEs were compared. It was observed that the LIG-based IDE sensor provided better sensitivity compared to that of the other two approaches. The obtained results indicate that the magnitude of impedance changes by around 2.5 [Formula: see text] per doubling of E.coli cells. With fast and flexible fabrication process capabilities, such microdevices may be used as suitable IDE sensors for microscale pathogenic detection for biomedical and clinical analysis.


Assuntos
Técnicas Biossensoriais , Escherichia coli , Eletrodos , Polímeros , Impedância Elétrica
18.
ACS Sens ; 8(4): 1373-1390, 2023 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-37074840

RESUMO

Presently, numerous state-of-the-art approaches are being adapted for gas sensing and monitoring. These include hazardous gas leak detection as well as ambient air monitoring. Photoionization detectors, electrochemical sensors, and optical infrared sensors are a few of the commonly widely used technologies. Extensive reviews on the current state of gas sensors have been summarized. These sensors, which are either nonselective or semiselective, are affected by unwanted analytes. On the other hand, volatile organic compounds (VOCs) can be heavily mixed in many vapor intrusion situations. To determine the individual VOCs in a highly mixed gas sample using nonselective or semiselective gas sensors, gas separation and discrimination technologies are highly warranted. These technologies include gas permeable membranes, metal-organic frameworks, microfluidics and IR bandpass filters for different sensors, respectively. The majority of these gas separation and discrimination technologies are currently being developed and evaluated in laboratory-controlled environments and have not yet been extensively utilized in the field for vapor intrusion monitoring. These technologies show promise for continued development and application in the field for more complex gas mixtures. Hence, the present review focuses on the perspectives and a summary of the existing gas separation and discrimination technologies for the currently popular reported gas sensors in environmental applications.


Assuntos
Gases , Compostos Orgânicos Voláteis
19.
Materials (Basel) ; 16(14)2023 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-37512303

RESUMO

In this work, we study the effects of treating nanostructured SnO2-SiO2 films derived by a sol-gel method with nitrogen and oxygen plasma. The structural and chemical properties of the films are closely investigated. To quantify surface site activity in the films following treatment, we employed a photocatalytic UV degradation test with brilliant green. Using X-ray photoelectron spectroscopy, it was found that treatment with oxygen plasma led to a high deviation in the stoichiometry of the SnO2 surface and even the appearance of a tin monoxide phase. These samples also exhibited a maximum photocatalytic activity. In contrast, treatment with nitrogen plasma did not lead to any noticeable changes in the material. However, increasing the power of the plasma source from 250 W to 500 W led to the appearance of an SnO fraction on the surface and a reduction in the photocatalytic activity. In general, all the types of plasma treatment tested led to amorphization in the SnO2-SiO2 samples.

20.
Biomicrofluidics ; 16(6): 061505, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36483020

RESUMO

With the advent of cyber-physical system-based automation and intelligence, the development of flexible and wearable devices has dramatically enhanced. Evidently, this has led to the thrust to realize standalone and sufficiently-self-powered miniaturized devices for a variety of sensing and monitoring applications. To this end, a range of aspects needs to be carefully and synergistically optimized. These include the choice of material, micro-reservoir to suitably place the analytes, integrable electrodes, detection mechanism, microprocessor/microcontroller architecture, signal-processing, software, etc. In this context, several researchers are working toward developing novel flexible devices having a micro-reservoir, both in flow-through and stationary phases, integrated with graphanized zones created by simple benchtop lasers. Various substrates, like different kinds of cloths, papers, and polymers, have been harnessed to develop laser-ablated graphene regions along with a micro-reservoir to aptly place various analytes to be sensed/monitored. Likewise, similar substrates have been utilized for energy harvesting by fuel cell or solar routes and supercapacitor-based energy storage. Overall, realization of a prototype is envisioned by integrating various sub-systems, including sensory, energy harvesting, energy storage, and IoT sub-systems, on a single mini-platform. In this work, the diversified work toward developing such prototypes will be showcased and current and future commercialization potential will be projected.

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