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Analytical Chemistry Jun 2024The development of sensors for detection of biomarkers exhibits an exciting potential in diagnosis of diseases. Herein, we propose a novel electrochemical sensing...
The development of sensors for detection of biomarkers exhibits an exciting potential in diagnosis of diseases. Herein, we propose a novel electrochemical sensing strategy for label-free dual-biomarker detection, which is based on the combination of stimulus-responsive molecularly imprinted polymer (MIP)-modified nanopores and a polymeric membrane chronopotentiometric sensor. The ion fluxes galvanostatically imposed on the sensing membrane surface can be blocked by the recognition reaction between the target biomarker in the sample solution and the stimulus-responsive MIP receptor in the nanopores, thus causing a potential change. By using two external stimuli (i.e., pH and temperature), the recognition abilities of the stimulus-responsive MIP receptor can be effectively modulated so that dual-biomarker label-free chronopotentiometric detection can be achieved. Using alpha fetoprotein (AFP) and prostate-specific antigen (PSA) as model biomarkers, the proposed sensor offers detection limits of 0.17 and 0.42 ng/mL for AFP and PSA, respectively.
Topics: Prostate-Specific Antigen; Nanopores; Molecularly Imprinted Polymers; alpha-Fetoproteins; Humans; Biomarkers; Limit of Detection; Electrochemical Techniques; Hydrogen-Ion Concentration; Biosensing Techniques; Potentiometry; Polymers; Molecular Imprinting; Temperature
PubMed: 38683892
DOI: 10.1021/acs.analchem.3c05817 -
Analytica Chimica Acta May 2024Monitoring extracellular calcium ion (Ca) chemical signals in neurons is crucial for tracking physiological and pathological changes associated with brain diseases in...
Monitoring extracellular calcium ion (Ca) chemical signals in neurons is crucial for tracking physiological and pathological changes associated with brain diseases in live animals. Potentiometry based solid-state ion-selective electrodes (ISEs) with the assist of functional carbon nanomaterials as ideal solid-contact layer could realize the potential response for in vitro and in vivo analysis. Herein, we employ a kind of biomass derived porous carbon as a transducing layer to prompt efficient ion to electron transduction while stabilizes the potential drift. The eco-friendly porous carbon after activation (APB) displays a high specific area with inherit macropores, micropores, and large specific capacitance. When employed as transducer in ISEs, a stable potential response, minimized potential drift can be obtained. Benefiting from these excellent properties, a solid-state Ca selective carbon fiber electrodes (CFEs) with a sandwich structure is constructed and employed for real time sensing of Ca under electrical stimulation. This study presents a new approach to develop sustainable and versatile transducers in solid-state ISEs, a crucial way for in vivo sensing.
Topics: Calcium; Carbon; Nanostructures; Ion-Selective Electrodes; Animals; Porosity; Transducers; Electrochemical Techniques
PubMed: 38677844
DOI: 10.1016/j.aca.2024.342590 -
Journal of Colloid and Interface Science Aug 2024The sandwich approach, whereby an antigen is captured by a primary antibody and detected by a secondary antibody, is commonly used to improve the selectivity and...
The sandwich approach, whereby an antigen is captured by a primary antibody and detected by a secondary antibody, is commonly used to improve the selectivity and sensitivity of enzyme-linked immunosorbent assays (ELISA). This work details the experimental factors that impact the reliable translation of this sandwich approach to two commonly used electronic biosensors, namely potentiometric and impedimetric biosensors. Previous studies have demonstrated the Debye screening limitations associated with potentiometric biosensors. However, the correlation between the ionic strength of the measurement buffer and the impedimetric biosensing response has not been studied. Potentiometric biosensors were able to successfully detect the primary antibody and the target antigen by decreasing the ionic strength of the phosphate buffered saline (PBS) measurement buffer from 1x PBS to 0.01x PBS. However, the secondary antibody used for the selective signal amplification was not reliably detected. Therefore, the sandwich approach is not viable for potentiometric sensing at biologically relevant ionic strengths, due to the Debye screening effect. Alternatively, decreasing the ionic strength of the measurement buffer allowed for the successful translation of the sandwich approach to impedimetric biosensors. Impedimetric biosensing literature typically attributes a measured increase in the charge transfer resistance to an increase in the thickness of the immobilized biolayer. However, this work highlights the influence that both the charge and thickness of the biolayer have on the transport of the redox couple. Decreasing the ionic strength of the measurement buffer lowers the molecular charge screening effect. This permits the transport of a positively charged redox probe through a negatively charged immobilized biolayer via migration and diffusion. The results demonstrate that the use of a buffer at a lower, yet biologically relevant ionic strength allows for the successful translation of the sandwich approach to impedimetric biosensors.
Topics: Enzyme-Linked Immunosorbent Assay; Biosensing Techniques; Osmolar Concentration; Potentiometry
PubMed: 38677211
DOI: 10.1016/j.jcis.2024.04.139 -
International Journal of Molecular... Apr 2024nitroreductase A (NfsA) is a candidate for gene-directed prodrug cancer therapy using bioreductively activated nitroaromatic compounds (ArNO). In this work, we...
nitroreductase A (NfsA) is a candidate for gene-directed prodrug cancer therapy using bioreductively activated nitroaromatic compounds (ArNO). In this work, we determined the standard redox potential of FMN of NfsA to be -215 ± 5 mV at pH 7.0. FMN semiquinone was not formed during 5-deazaflavin-sensitized NfsA photoreduction. This determines the two-electron character of the reduction of ArNO and quinones (Q). In parallel, we characterized the oxidant specificity of NfsA with an emphasis on its structure. Except for negative outliers nitracrine and SN-36506, the reactivity of ArNO increases with their electron affinity (single-electron reduction potential, ) and is unaffected by their lipophilicity and Van der Waals volume up to 386 Å. The reactivity of quinoidal oxidants is not clearly dependent on , but 2-hydroxy-1,4-naphthoquinones were identified as positive outliers and a number of compounds with diverse structures as negative outliers. 2-Hydroxy-1,4-naphthoquinones are characterized by the most positive reaction activation entropy and the negative outlier tetramethyl-1,4-benzoquinone by the most negative. Computer modelling data showed that the formation of H bonds with Arg15, Arg133, and Ser40, plays a major role in the binding of oxidants to reduced NfsA, while the role of the π-π interaction of their aromatic structures is less significant. Typically, the calculated hydride-transfer distances during ArNO reduction are smallwer than for Q. This explains the lower reactivity of quinones. Another factor that slows down the reduction is the presence of positively charged aliphatic substituents.
Topics: Nitroreductases; Prodrugs; Substrate Specificity; Escherichia coli; Oxidation-Reduction; Escherichia coli Proteins; Potentiometry; Catalysis; Molecular Docking Simulation
PubMed: 38673999
DOI: 10.3390/ijms25084413 -
ACS Sensors May 2024Selective and nondisruptive in vivo neurochemical monitoring within the central nervous system has long been a challenging endeavor. We introduce a new sensing approach...
Selective and nondisruptive in vivo neurochemical monitoring within the central nervous system has long been a challenging endeavor. We introduce a new sensing approach that integrates neurocompatible galvanic redox potentiometry (GRP) with customizable phosphorothioate aptamers to specifically probe dopamine (DA) dynamics in live rat brains. The aptamer-functionalized GRP (aptGRP) sensor demonstrates nanomolar sensitivity and over a 10-fold selectivity for DA, even amidst physiological levels of major interfering species. Notably, conventional sensors without the aptamer modification exhibit negligible reactivity to DA concentrations exceeding 20 μM. Critically, the aptGRP sensor operates without altering neuronal activity, thereby permitting real-time, concurrent recordings of both DA flux and electrical signaling in vivo. This breakthrough establishes aptGRP as a viable and promising framework for the development of high-fidelity sensors, offering novel insights into neurotransmission dynamics in a live setting.
Topics: Animals; Aptamers, Nucleotide; Dopamine; Rats; Potentiometry; Brain; Biosensing Techniques; Rats, Sprague-Dawley; Male
PubMed: 38659329
DOI: 10.1021/acssensors.4c00119 -
Advanced Science (Weinheim,... Apr 2024Self-powered pressure detection using smart wearable devices is the subject of intense research attention, which is intended to address the critical need for prolonged...
Self-powered pressure detection using smart wearable devices is the subject of intense research attention, which is intended to address the critical need for prolonged and uninterrupted operations. Current piezoelectric and triboelectric sensors well respond to dynamic stimuli while overlooking static stimuli. This study proposes a dual-response potentiometric pressure sensor that responds to both dynamic and static stimuli. The proposed sensor utilizes interdigital electrodes with MnO/carbon/polyvinyl alcohol (PVA) as the cathode and conductive silver paste as the anode. The electrolyte layer incorporates a mixed hydrogel of PVA and phosphoric acid. The optimized interdigital electrodes and sandpaper-like microstructured surface of the hydrogel electrolyte contribute to enhanced performance by facilitating an increased contact area between the electrolyte and electrodes. The sensor features an open-circuit voltage of 0.927 V, a short-circuit current of 6 µA, a higher sensitivity of 14 mV/kPa, and outstanding cycling performance (>5000 cycles). It can accurately recognize letter writing and enable capacitor charging and LED lighting. Additionally, a data acquisition and display system employing the proposed sensor, which facilitates the monitoring of athletes' rehabilitation training, and machine learning algorithms that effectively guide rehabilitation actions are presented. This study offers novel solutions for the future development of smart wearable devices.
PubMed: 38654624
DOI: 10.1002/advs.202401515 -
Frontiers in Molecular Biosciences 2024The most common skin diseases include eczema, psoriasis, acne, and fungal infections. There is often no effective cure for them. Increasing antimicrobial drug resistance...
The most common skin diseases include eczema, psoriasis, acne, and fungal infections. There is often no effective cure for them. Increasing antimicrobial drug resistance prompts us to search for new, safe, and effective therapeutics. Among such interesting candidates are peptides derived from milk fermented with specific lactic acid bacteria or with kombucha cultures, which are a potential treasure trove of bioactive peptides. Four of them are discussed in this article. Their interactions with zinc and copper ions, which are known to improve the well-being of the skin, were characterized by potentiometry, MS, ITC, and spectroscopic methods, and their cytostatic potential was analyzed. The results suggest that they are safe for human cells and can be used alone or in complexes with copper for further testing as potential therapeutics for skin diseases.
PubMed: 38638688
DOI: 10.3389/fmolb.2024.1366588 -
International Journal of Biological... May 2024The present work demonstrates the correlation between structure, properties, and self-sensing protocols of in situ prepared ferric oxide doped grafted copolymer...
The present work demonstrates the correlation between structure, properties, and self-sensing protocols of in situ prepared ferric oxide doped grafted copolymer composite, comprised of ferric oxide, chitosan, and polypyrrole (α-FeO-en-CHIT-g-PPy) for residual ibuprofen present in natural and artificial samples. The chemical structure, morphology, functionality, and physio-mechanical properties of the composite were determined by Fourier transform infrared spectrometer (FT-IR), Raman spectra, X-ray diffraction (XRD), Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Two probe method, and standard ASTM techniques to explore sensing nature. The results confirm the evolution of axially aligned structure against 110 planes of α-FeO and chemically functionalized expanded polymer matrix during in-situ chemical polymerization of pyrrole, with better porosity, interactivity, and improved electrical conductivity i.e. 7.32 × 10 S cm. Further, a thin film of prepared composite coated on an ITO glass plate was explored for potentiometric sensing of ibuprofen (IBU) present in artificial and natural samples without the use of any additional energy sources. The observed sensing parameters are the sensing ranging 0.5 μM to 100.0 μM, sensitivity 2.5081 mV μM cm, response time 50 s, recovery time 10 s, and stability for 60 days. The sensing mechanism of the IBU sensor and effective charge transfer in the electrode was also discussed based on changes in IR spectra of the electrode recorded before and after sensing due to surface oxidation of IBU due to the presence of iron and doping effect of iron oxide in the composite.
Topics: Chitosan; Pyrroles; Ibuprofen; Polymers; Ferric Compounds; Electrodes; Potentiometry; Spectroscopy, Fourier Transform Infrared
PubMed: 38621570
DOI: 10.1016/j.ijbiomac.2024.131598 -
International Journal of Biological... May 2024Cuttlefish bone biowaste is a potential source of a composite matrix based on chitin and aragonite. In the present work, we propose for the first time the elaboration of...
Cuttlefish bone biowaste is a potential source of a composite matrix based on chitin and aragonite. In the present work, we propose for the first time the elaboration of biocomposites based on chitosan and aragonite through the valorization of bone waste. The composition of the ventral and dorsal surfaces of bone is well studied by ICP-OES. An extraction process has been applied to the dorsal surface to extract β-chitin and chitosan with controlled physico-chemical characteristics. In parallel, aragonite isolation was carried out on the ventral side. The freeze-drying method was used to incorporate aragonite into the chitosan polymer to form CHS/ArgS biocomposites. Physicochemical characterizations were performed by FT-IR, SEM, XRD, H NMR, TGA/DSC, potentiometry and viscometry. The ICP-OES method was used to evaluate in vitro the bioactivity level of biocomposite in simulated human plasma (SBF), enabling analysis of the interactions between the material and SBF. The results obtained indicate that the CHS/ArgS biocomposite derived from cuttlefish bone exhibits bioactivity, and that chitosan enhances the bioactivity of aragonite. The CHS/ArgS biocomposite showed excellent ability to form an apatite layer on its surface. After three days' immersion, FTIR and SEM analyses confirmed the formation of this layer.
Topics: Chitosan; Decapodiformes; Animals; Calcium Carbonate; Biocompatible Materials; Bone and Bones; Spectroscopy, Fourier Transform Infrared; Chemical Phenomena; Humans
PubMed: 38615864
DOI: 10.1016/j.ijbiomac.2024.131554 -
Analytica Chimica Acta May 2024Defining the distribution of the chemical species in a multicomponent system is a task of great importance with applications in many fields. To clarify the identity and... (Review)
Review
Defining the distribution of the chemical species in a multicomponent system is a task of great importance with applications in many fields. To clarify the identity and the abundance of the species that can be formed by the interaction of the components of a solution, it is fundamental to know the formation constants of those species. The determination of equilibrium constants is mainly performed through the analysis of experimental data obtained by different instrumental techniques. Among them, potentiometry is the elective technique for this purpose. As such, a survey was run within the NECTAR COST Action - Network for Equilibria and Chemical Thermodynamics Advanced Research, to identify the most used software for the analysis of potentiometric data and to highlight their strengths and weaknesses. The features and the calculation processes of each software were analyzed and rationalized, and a simulated titration dataset of a hypothetic hexaprotic acid was processed by each software to compare and discuss the optimized protonation constants. Moreover, further data analysis was also carried out on the original dataset including some systematic errors from different sources, as some calibration parameters, the total analytical concentration of reagents and ionic strength variations during titrations, to evaluate their impact on the refined parameters. Results showed that differences on the protonation constants estimated by the tested software are not significant, while some of the considered systematic errors affect results. Overall, it emerged that software commonly used suffer from many limitations, highlighting the urgency of new dedicated and modern tools. In this context, some guidelines for data generation and treatment are also given.
PubMed: 38609256
DOI: 10.1016/j.aca.2024.342476