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Electrochemical biosensing has emerged as a promising method for the point-of-care detection of various biomarkers. However, its clinical application faces significant challenges due to biofouling when exposed to clinical samples. This study presents a novel nanocomposite coating aimed at addressing biofouling in electrochemical biosensors by developing an Electrochemical Estradiol Aptasensor (EAS). We developed a nanoengineered, hybrid hydrogel-based 3D antifouling nanocomposite interface (ANcI) by crosslinking carboxymethyl chitosan with sodium carboxymethyl cellulose and incorporating highly conductive Ti3C2Tx MXene nanostructures. The Aptasensor was constructed on a screen-printed carbon electrode by applying the ANcI as an antifouling layer, followed by the deposition of a gold nanoparticle support layer modified with estradiol-specific aptamers, which serves as the biorecognition element. We evaluated the antifouling capabilities by comparing the performance of the Aptasensor with and without the ANcI when exposed to human serum and bovine serum albumin. This innovative nanocomposite coating offers excellent antifouling properties along with a highly porous structure and electrical conductivity, which are essential for maintaining sensor performance in complex clinical samples. By addressing the limitations of existing antifouling materials, this approach paves the way for the commercialization of electrochemical biosensors with enhanced accuracy and sensitivity. The sensors demonstrate a clinically relevant concentration range of 0.1 pg/mL to 1000 pg/mL, with a limit of detection of 0.127 pg/mL. These findings highlight the potential of this innovative approach to improve electrochemical biosensing across various applications and significantly impact biomarker detection in clinical samples.
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Aptâmeros de Nucleotídeos , Incrustação Biológica , Técnicas Biossensoriais , Técnicas Eletroquímicas , Estradiol , Hidrogéis , Nanocompostos , Técnicas Biossensoriais/métodos , Nanocompostos/química , Humanos , Técnicas Eletroquímicas/métodos , Incrustação Biológica/prevenção & controle , Aptâmeros de Nucleotídeos/química , Estradiol/análise , Estradiol/sangue , Estradiol/química , Hidrogéis/química , Quitosana/química , Quitosana/análogos & derivados , Ouro/química , Animais , Bovinos , Eletrodos , Soroalbumina Bovina/química , Nanopartículas Metálicas/químicaRESUMO
AIMS: This study aims to develop an advanced model for the classification of Diabetic Macular Edema (DME) using deep learning techniques. Specifically, the objective is to introduce a novel architecture, SSCSAC-Net, that leverages self-supervised learning and category-selective attention mechanisms to improve the precision of DME classification. METHODS: The proposed SSCSAC-Net integrates self-supervised learning to effectively utilize unlabeled data for learning robust features related to DME. Additionally, it incorporates a category-specific attention mechanism and a domain-specific layer into the ResNet-152 base architecture. The model is trained using an ensemble of unsupervised and supervised learning techniques. Benchmark datasets are utilized for testing the model's performance, ensuring its robustness and generalizability across different data distributions. RESULTS: Evaluation of the SSCSAC-Net on multiple datasets demonstrates its superior performance compared to existing techniques. The model achieves high accuracy, precision, and recall rates, with an accuracy of 98.7%, precision of 98.6%, and recall of 98.8%. Furthermore, the incorporation of self-supervised learning reduces the dependency on extensive labeled data, making the solution more scalable and cost-effective. CONCLUSIONS: The proposed SSCSAC-Net represents a significant advancement in automated DME classification. By effectively using self-supervised learning and attention mechanisms, the model offers improved accuracy in identifying DME-related features within retinal images. Its robustness and generalizability across different datasets highlight its potential for clinical applications, providing a valuable tool for clinicians in diagnosing DME effectively.
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Aprendizagem Profunda , Retinopatia Diabética , Edema Macular , Humanos , Edema Macular/classificação , Edema Macular/diagnóstico , Retinopatia Diabética/classificação , Retinopatia Diabética/diagnóstico , Aprendizado de Máquina Supervisionado , Redes Neurais de ComputaçãoRESUMO
The effective removal and displacement of fluids is important in many industrial and environmental applications, such as for operation and cleaning of process equipment, fluid injection in porous media for oil recovery or aquifer remediation, or for achieving subsurface zonal isolation in new or abandoned wells. The accurate measurement of the residual fluid wall film left behind after displacement by a cleaning fluid is a long-standing challenge, particularly so for very thin fluid films where the thickness can be of the order of micrometer. We focus on the characterization of oil films left on the wall of a horizontal pipe after the pipe has been displaced by water, and develop a novel, non-intrusive analytical technique that allows the use of relevant pipe materials. The oil that originally occupies the pipe is stained by a hydrophobic dye Nile red, and an intermediate organic solvent is used to collect the residual oil volume that remains after displacing the pipe with a known volume of water. Finally, ultraviolet-visible spectroscopy is used to measure the Nile red concentration in the collected fluid, which is proportional to the residual volume of oil in the pipe. We demonstrate the methodology by conducting experiments where the displacing fluid is injected at two different imposed velocities, and where the injected fluid volume is varied. As expected, we find a gradual thinning of the oil film with increasing injected fluid volume. We compare the measured film thicknesses to a displacement model based on the steady velocity profile in a pipe, and find that experiments consistently produce smaller film thicknesses. This developed technique allows quantification of displacement and cleaning mechanisms involved in immiscible displacements at laminar, transitional and turbulent regimes, for different non-Newtonian fluid pairs, and for different realistic pipe materials and surface roughnesses.
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Injury to the superficial medial collateral ligament (MCL) is treated conservatively for low-grade injury and with surgery for high-grade injury, especially in association with cruciate ligament injury. Acute injuries are treated with MCL repair, and chronic injury requires reconstruction. Anatomic MCL reconstruction can be done using free allograft or autograft and fixed using screws or suspensory fixation. We describe here an anatomic technique that is a modification of a Danish technique in which we reroute the semitendinosus, keeping its tibial attachment intact. The semitendinosus is rerouted anatomically in the tibial tunnel, and a graft is then passed anatomically in the femoral tunnel. The graft is fixed in both tunnels with adjustable loop suspensory fixation, which gives the unique advantage of controlled tensioning of the graft for MCL reconstruction. In this technique further re-tensioning is possible if the knee is unstable in valgus stress, even after final fixation.
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Microelectrode-based cell chip studies for cellular responses often require improved adhesion and growth conditions for efficient cellular diagnosis and high throughput screening in drug discovery. Cell-chip studies are often performed on gold electrodes due to their biocompatibility, and stability, but the electrode-electrolyte interfacial capacitance is the main drawback to the overall sensitivity of the detection system. Thus, here, we developed reduced graphene oxide-polyaniline-modified gold microelectrodes for real-time impedance-based monitoring of human gastric adenocarcinoma cancer (MKN-1) cells. The impedance characterization on modified electrodes showed 28-fold enhanced conductivity than the bare electrodes, and the spectra were modeled with proper equivalent circuits to extrapolate the values of circuit elements. The impedance of both time-and frequency-dependent measurements of cell-covered modified electrodes with equivalent model circuits was analyzed to achieve cellular behavior, such as adhesion, spreading, proliferation, and influence of anti-cancer agents. The normalized impedance at 41.5 kHz (|Z|norm 41 kHz) was selected to monitor the cell growth analysis, which was found linear with the proliferation of adherent cells along with the influence of the anticancer drug agent on the MKN-1 cells. The synergistic effects and biocompatible nature of PANI-RGO modifications improved the overall sensitivity for the cell-growth studies of MKN-1 cells.
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Grafite , Neoplasias , Humanos , Microeletrodos , Impedância Elétrica , OuroRESUMO
Sensitive and selective determination of protein biomarkers with high accuracy often remains a great challenge due to their existence in the human body at an exceptionally low concentration level. Therefore, sensing mechanisms that are easy to use, simple, and capable of accurate quantification of analyte are still in development to detect biomarkers at a low concentration level. To meet this end, we demonstrated a methodology to detect thrombin in serum at low concentration levels using polypyrrole (PPy)-palladium (Pd)nanoparticle-based hybrid transducers using liposomes encapsulated redox marker as a label. The morphology of Ppy-Pd composites was characterized by scanning electron microscopy, and the hybrid structure provided excellent binding and detection platform for thrombin detection in both buffer and serum solutions. For quantitative measurement of thrombin in PBS and serum, the change in current was monitored using differential pulse voltammetry, and the calculated limit of quantification (LOQ) and limit of detection (LOD) for the linear segment (0.1-1000 nM of thrombin) were 1.1 pM and 0.3 pM, in serum, respectively. The sensors also exhibited good stability and excellent selectivity towards the detection of thrombin, and thus make it a strong candidate for adopting its sensing applications in biomarker detection technologies.
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Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Nanocompostos , Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Humanos , Limite de Detecção , Lipossomos , Paládio/química , Polímeros/química , Pirróis/química , Trombina/químicaRESUMO
Metal-organic frameworks (MOFs) are a class of porous organic-inorganic solids extensively explored for numerous applications owing to their catalytic activity and high surface area. In this work MOF thin films deposited in a one-step, molecular layer deposition (MLD), an all-gas-phase process, on glass wool fibers are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and their capabilities towards toxic industrial chemical (TIC) capture and chemical warfare agents (CWA) degradation are investigated. It is shown that despite low volume of the active material used, MOFs thin films are capable of removal of harmful gaseous chemicals from air stream and CWA from neutral aqueous environment. The results confirm that the MLD-deposited MOF thin films, amorphous and crystalline, are suitable materials for use in air filtration, decontamination, and physical protection against CWA and TIC.
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This review reports the recent advances in surface-enhanced Raman scattering (SERS)-based lateral flow assay (LFA) platforms for the diagnosis of infectious diseases. As observed through the recent infection outbreaks of COVID-19 worldwide, a timely diagnosis of the disease is critical for preventing the spread of a disease and to ensure epidemic preparedness. In this regard, an innovative point-of-care diagnostic method is essential. Recently, SERS-based assay platforms have received increasing attention in medical communities owing to their high sensitivity and multiplex detection capability. In contrast, LFAs provide a user-friendly and easily accessible sensing platform. Thus, the combination of LFAs with a SERS detection system provides a new diagnostic modality for accurate and rapid diagnoses of infectious diseases. In this context, we briefly discuss the recent application of LFA platforms for the POC diagnosis of SARS-CoV-2. Thereafter, we focus on the recent advances in SERS-based LFA platforms for the early diagnosis of infectious diseases and their applicability for the rapid diagnosis of SARS-CoV-2. Finally, the key issues that need to be addressed to accelerate the clinical translation of SERS-based LFA platforms from the research laboratory to the bedside are discussed.
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Development of a very sensitive biosensor is accompanied with an inevitable shrinkage in the linear detection range. Here, we developed an electrochemical biosensor with a novel methodology to detect microRNA-21 (miR21) at an ultralow level and broad linear detection range. A three-way junction RNA structure was designed harboring (i) a methylene blue (MB)-modified hairpin structure at its one leg to function as the sensing moiety and (ii) the other two legs to be further hybridized with barcode gold nanoparticles (MB/barG) as the signal amplifiers. Addition of target miR21 resulted in opening the hairpin moiety and subsequent hybridization with DNA-modified gold nanoflower/platinum electrode (GNF@Pt) to form the MB-3 sensor. Inspired by the relay-race run, to extend the dynamic detection range and increase the sensitivity of the biosensor, MB/barG was added to form the second detection modality (MBG-3). The combined sensor required very low sample volume (4⯵L) and could identify 135 aM or 324 molecules of miR21 with the ability to operate within a wide linear range from 1⯵M down to 500 aM. The fabricated GNF@Pt showed a remarkable conductivity compared with the gold nanoparticle-modified electrode. Addition of MB/barG boosted the electrochemical signal of the MB by almost 230 times. Moreover, a new protocol was introduced by the authors to increase the efficiency of microRNA extraction from the total serum. Possessing a sound selectivity and specificity towards single base-pair mutations, the developed biosensor could profile cancer development stages of two patient serums.
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Técnicas Biossensoriais/instrumentação , Ouro/química , Nanopartículas Metálicas/química , MicroRNAs/sangue , Técnicas Eletroquímicas/instrumentação , Eletrodos , Desenho de Equipamento , Humanos , Limite de Detecção , Hibridização de Ácido NucleicoRESUMO
The air-free reaction between FeCl(2) and H(4)dobdc (dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate) in a mixture of N,N-dimethylformamide (DMF) and methanol affords Fe(2)(dobdc)·4DMF, a metal-organic framework adopting the MOF-74 (or CPO-27) structure type. The desolvated form of this material displays a Brunauer-Emmett-Teller (BET) surface area of 1360 m(2)/g and features a hexagonal array of one-dimensional channels lined with coordinatively unsaturated Fe(II) centers. Gas adsorption isotherms at 298 K indicate that Fe(2)(dobdc) binds O(2) preferentially over N(2), with an irreversible capacity of 9.3 wt %, corresponding to the adsorption of one O(2) molecule per two iron centers. Remarkably, at 211 K, O(2) uptake is fully reversible and the capacity increases to 18.2 wt %, corresponding to the adsorption of one O(2) molecule per iron center. Mössbauer and infrared spectra are consistent with partial charge transfer from iron(II) to O(2) at low temperature and complete charge transfer to form iron(III) and O(2)(2-) at room temperature. The results of Rietveld analyses of powder neutron diffraction data (4 K) confirm this interpretation, revealing O(2) bound to iron in a symmetric side-on mode with d(O-O) = 1.25(1) Å at low temperature and in a slipped side-on mode with d(O-O) = 1.6(1) Å when oxidized at room temperature. Application of ideal adsorbed solution theory in simulating breakthrough curves shows Fe(2)(dobdc) to be a promising material for the separation of O(2) from air at temperatures well above those currently employed in industrial settings.
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The microporous metal-organic framework Ni(2)(dhtp) (H(4)dhtp=2,5-dihydroxyterephthalic acid) shows distinct end-on CO(2) coordination to coordinatively unsaturated nickel sites giving rise to high CO(2) adsorption capacity at sub-atmospheric pressures and ambient temperatures.
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The structure of the nickel N,N'-piperazinebismethylenephosphonate, Ni-STA-12 (St. Andrews porous material-12), has been determined in the hydrated (Ni2L x 8 H2O, L = O3PCH2NC4H8NCH2PO3), partially dehydrated (Ni2L x 2 H2O), and fully dehydrated (Ni2L) forms from high-resolution synchrotron X-ray powder diffraction. The framework structures of Ni2L x 8 H2O and Ni2L x 2 H2O are almost identical (R, a = 27.8342(1) A, c = 6.2421(2) A; R, a = 27.9144(1) A, c = 6.1655(2) A) with additional physisorbed water of the as-prepared Ni-STA-12 present in an ordered hydrogen-bonded network in the channels. Ab initio structure solution of the fully dehydrated solid indicates it has changed symmetry to triclinic (P1, a = 6.03475(5) A, b = 14.9157(2) A, c = 16.1572(2) A, alpha = 112.5721(7) degrees, beta = 95.7025(11) degrees, gamma = 96.4950(11) degrees) as a result of a topotactic structural rearrangement. The fully dehydrated solid possesses permanent porosity with elliptical channels 8 A x 9 A in free diameter. The structural change results from the loss of water coordinated to the nickel cations, so that the nickel coordination changes from edge-sharing octahedral NiO5N to edge- and corner-sharing five-fold NiO4N. During this change, two out of three phosphonate groups rotate to become fully coordinated to nickel cations, leaving the remainder of the phosphonate groups coordinated to nickel cations by two oxygen atoms and with a P=O bond projecting into the channels. This transformation, which is completely reversible, causes substantial changes in both vibrational and electronic properties as shown by IR, Raman, and UV-visible spectroscopies. Complementary adsorption, calorimetric, and infrared studies of the probe adsorbates H2, CO, and CO2 reveal the presence of several distinct adsorption sites in the solid, which are attributed to their interactions with nickel cations which are weak Lewis acid sites, as well as with P=O groups that project into the pores. At 304 K, the adsorption isotherms and enthalpies of adsorption on dehydrated Ni-STA-12 have been measured for CO2 and CH4: Ni-STA-12 gives adsorption uptakes of CO2 of 2.5 mmol g(-1) at 1 bar, an uptake ca. 10 times that of CH4.