-
ACS Omega May 2022The complexes formed between Pb and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) were reinvestigated in aqueous solutions using a combination of pH...
Revisiting Lead(II)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic Acid Coordination Chemistry in Aqueous Solutions: Evidence of an Underestimated Thermodynamic Stability.
The complexes formed between Pb and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) were reinvestigated in aqueous solutions using a combination of pH potentiometry, UV-vis spectroscopy, and NMR spectroscopy. The thermodynamic data were supported by kinetics assays. Differently protonated complexes, ., [PbHL], [PbHL], [PbHL], and [PbL], were detected, and the corresponding stability constants (log) at = 298 K and = 0.1 M NaCl were 33.1 ± 0.2, 32.00 ± 0.06, 29.28 ± 0.06, and 25.3 ± 0.1, respectively. Results differed significantly from those previously reported by Chaves (Talanta1992, 39, 249) and Pippin (Inorg. Chim. Acta1995, 239, 43) in both the speciation and the overall complex stability; the latter in particular was found to be remarkably higher. The work disclosed herein provides revised data on the Pb-DOTA complexes, which should be used as a new stability benchmark during the development of lead chelators.
PubMed: 35571797
DOI: 10.1021/acsomega.2c00387 -
Sensors (Basel, Switzerland) Nov 2023In the present work, potentiometric sensors with polymer membranes used for chlorhexidine (CHXD) determination were developed. The polymer membranes were plasticized...
In the present work, potentiometric sensors with polymer membranes used for chlorhexidine (CHXD) determination were developed. The polymer membranes were plasticized with bis(2-ethylheksyl)sebacate (DOS) or 2-nitrophenyloctyl ether (-NPOE). The active compounds used in the membrane were cyclodextrins, crown ethers, and ion exchangers. The best-constructed electrode was based on neutral heptakis(2,3,6-tri-O-benzoyl)--cyclodextrin with lipophilic salt (KTpClBP)-potassium tetrakis(4-chlorophenyl) borate-dissolved in plasticizer, DOS. The presented electrode is characterized by an average cationic slope of 30.9 ± 2.9 mV decade within a linear range of 1 × 10 to 1 × 10 mol × L, while the value of the correlation coefficient is 0.9970 ± 0.0026. The response time was about 5 s when increasing the sample concentration and about 10 s when diluting the sample. The electrode potential is independent of the pH within a range of 4.0-9.5. The polymeric membrane sensor was successfully applied for assays of chlorhexidine digluconate in pure samples and pharmaceutical samples. The relative error from three replicate measurements was determined to be 1.1%. and the accuracy was RSD = 0.3-1.1%.
Topics: Chlorhexidine; Membranes, Artificial; Electrodes; Potentiometry; Polymers; Hydrogen-Ion Concentration
PubMed: 38067881
DOI: 10.3390/s23239508 -
Molecules (Basel, Switzerland) Nov 2022Stability-indicating methods are awesome tools to ensure the safety and efficacy of active pharmaceutical ingredients (APIs). An accurate comparative study involving the...
Stability-indicating methods are awesome tools to ensure the safety and efficacy of active pharmaceutical ingredients (APIs). An accurate comparative study involving the use of potentiometric sensors for the determination of bromazepam (BRZ) in the presence of its main product of degradation and impurity was performed by the fabrication of two membrane electrodes. A screen-printed electrode (SPE) and a solid-contact glassy carbon electrode (SCE) were fabricated and their performance optimized. The fabricated sensors showed a linear electrochemical response in the concentration range 1.0 × 10 M to 1.0 × 10 M. The electrodes exhibited Nernstian slopes of 59.70 mV/decade and 58.10 mV/decade for the BRZ-SPE and BRZ-SCE membrane electrodes, respectively. The electrochemical performance was greatly affected by the medium pH. They showed an almost ideal electrochemical performance between pH 3.0 and pH 6.0. The fabricated membranes were applied successfully for the quantification of BRZ in the presence of up to 90% of its degradation product. Moreover, a successful application of the fabricated electrodes was performed for the sensitive and selective quantification of BRZ in its tablet form without any pretreatment procedure.
Topics: Bromazepam; Electrodes; Potentiometry; Carbon; Tablets
PubMed: 36364443
DOI: 10.3390/molecules27217616 -
Biosensors & Bioelectronics Apr 2022The field of electrochemical biosensors has been dominated by amperometric and voltammetric sensors; however, these are limited greatly in their signal dependence on...
The field of electrochemical biosensors has been dominated by amperometric and voltammetric sensors; however, these are limited greatly in their signal dependence on electrode size. Open circuit potentiometric sensors are emerging as an alternative due to their signal insensitivity to electrode size. Here, we present a second-generation biosensor that uses a modified chitosan hydrogel to entrap a dehydrogenase or other oxidoreductase enzyme of interest. The chitosan is modified with a desired electron mediator such that in the presence of the analyte, the enzyme will oxidize or reduce the mediator, thus altering the measured interfacial potential. Using the above design, we demonstrate a swift screening method for appropriate enzyme-mediator pairs based on open circuit potentiometry, as well as the efficacy of the biosensor design using two dehydrogenase enzymes (FADGDH and ADH) and peroxidase. Using 1,2-naphthoquinone as the mediator for FADGDH, dynamic ranges from 0.1 to 50 mM glucose are achieved. We additionally demonstrate the ease of fabrication and modification, a lifetime of ≥28 days, insensitivity to interferents, miniaturization to the microscale, and sensor efficacy in the presence of the enzyme's natural cofactor. These results forge a foundation for the generalized use of potentiometric biosensors for a wide variety of analytes within biologically-relevant systems where oxygen can be an interferent.
Topics: Biosensing Techniques; Electrodes; Glucose; Oxygen; Potentiometry
PubMed: 35032843
DOI: 10.1016/j.bios.2021.113888 -
Frontiers in Human Neuroscience 2016Traumatic brain injury (TBI) has been identified as an important cause of death and severe disability in all age groups and particularly in children and young adults....
Traumatic brain injury (TBI) has been identified as an important cause of death and severe disability in all age groups and particularly in children and young adults. Central to TBIs devastation is a delayed secondary injury that occurs in 30-40% of TBI patients each year, while they are in the hospital Intensive Care Unit (ICU). Secondary injuries reduce survival rate after TBI and usually occur within 7 days post-injury. State-of-art monitoring of secondary brain injuries benefits from the acquisition of high-quality and time-aligned electrical data i.e., ElectroCorticoGraphy (ECoG) recorded by means of strip electrodes placed on the brains surface, and neurochemical data obtained via rapid sampling microdialysis and microfluidics-based biosensors measuring brain tissue levels of glucose, lactate and potassium. This article progresses the field of multi-modal monitoring of the injured human brain by presenting the design and realization of a new, compact, medical-grade amperometry, potentiometry and ECoG recording bioinstrumentation. Our combined TBI instrument enables the high-precision, real-time neuroelectrochemical monitoring of TBI patients, who have undergone craniotomy neurosurgery and are treated sedated in the ICU. Electrical and neurochemical test measurements are presented, confirming the high-performance of the reported TBI bioinstrumentation.
PubMed: 27242477
DOI: 10.3389/fnhum.2016.00212 -
Analytical and Bioanalytical Chemistry Jan 2021Multi-analyte sensing using exclusively laser-induced graphene (LIG)-based planar electrode systems was developed for sweat analysis. LIG provides 3D structures of...
Multi-analyte sensing using exclusively laser-induced graphene (LIG)-based planar electrode systems was developed for sweat analysis. LIG provides 3D structures of graphene, can be manufactured easier than any other carbon electrode also on large scale, and in form of electrodes: hence, it is predestinated for affordable, wearable point-of-care sensors. Here, it is demonstrated that LIG facilitates all three electrochemical sensing strategies (voltammetry, potentiometry, impedance) in a multi-analyte system for sweat analysis. A potentiometric potassium-ion-selective electrode in combination with an electrodeposited Ag/AgCl reference electrode (RE) enabled the detection of potassium ions in the entire physiologically relevant range (1 to 500 mM) with a fast response time, unaffected by the presence of main interfering ions and sweat-collecting materials. A kidney-shaped interdigitated LIG electrode enabled the determination of the overall electrolyte concentration by electrochemical impedance spectroscopy at a fixed frequency. Enzyme-based strategies with amperometric detection share a common RE and were realized with Prussian blue as electron mediator and biocompatible chitosan for enzyme immobilization and protection of the electrode. Using glucose and lactate oxidases, lower limits of detection of 13.7 ± 0.5 μM for glucose and 28 ± 3 μM for lactate were obtained, respectively. The sensor showed a good performance at different pH, with sweat-collecting tissues, on a model skin system and furthermore in synthetic sweat as well as in artificial tear fluid. Response time for each analytical cycle totals 75 s, and hence allows a quasi-continuous and simultaneous monitoring of all analytes. This multi-analyte all-LIG system is therefore a practical, versatile, and most simple strategy for point-of-care applications and has the potential to outcompete standard screen-printed electrodes. Graphical abstract.
Topics: Biosensing Techniques; Electrochemical Techniques; Graphite; Humans; Ion-Selective Electrodes; Lasers; Point-of-Care Systems; Sweat
PubMed: 32989512
DOI: 10.1007/s00216-020-02939-4 -
Data in Brief Jun 2021The data presented in this article are related to the research paper "Granulation of fly ash and biochar with organic lake sediments - A way to sustainable utilization...
The data presented in this article are related to the research paper "Granulation of fly ash and biochar with organic lake sediments - A way to sustainable utilization of waste from bioenergy production" [1] in the context of waste material investigation and possible valorization instead of disposal. This article provides a comprehensive chemical and physical characterization of wood combustion products - fly ashes, bottom ashes, mixed ashes and biochar. Multiple analytical techniques and methodology were exploited to investigate the composition of wood combustion products, among them a loss on ignition, potentiometry, colorimetry, X-ray diffractometry, X-ray fluorescence spectrometry, inductively coupled plasma optical emission spectrometry, gas chromatography. General parameters detected were the content of dry matter, gravimetric water, volatile matter, amount of ash and fixed carbon. The elemental analysis involved determining C, H, N and O. Physical properties were described by bulk density, solid density, total porosity, electric conductivity, specific weight and mass ratio assessment of particle size distribution. The mineralogical composition was described by major crystalline phases of samples and content of oxides. Chemical properties and composition were characterized by pH, the content of ammonium, nitrates, nitrites, exchangeable elements and cation exchange capacity as well as after the 3-step speciation and analytical quantification of trace and major elements (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Sb, Se, Sr, Ti, Tl, V and Zn) and detection of polycyclic aromatic hydrocarbons.
PubMed: 33889697
DOI: 10.1016/j.dib.2021.106994 -
ACS Sensors Jan 2023Microneedle sensor technology offers exciting opportunities for decentralized clinical analyses. A novel issue puts forward herein is to demonstrate the uniqueness of...
Microneedle sensor technology offers exciting opportunities for decentralized clinical analyses. A novel issue puts forward herein is to demonstrate the uniqueness of membrane-based microneedles to accomplish real-time, on-body monitoring of multiple ions simultaneously. The use of multi-ion detection is clinically relevant since it is expected to provide a more complete and reliable assessment of the clinical status of a subject concerning electrolyte disorders and others. We present a microneedle system for transdermal multiplexed tracing of pH, Na, K, Ca, Li, and Cl. The device consists of an array of seven solid microneedles externally modified to provide six indicator electrodes, each selective for a different ion, and a common reference electrode, all integrated into a wearable patch read in a potentiometric mode. We show in vitro measurements at the expected clinical levels, resulting in a fast response time, excellent reversibility and repeatability, and adequate selectivity. Close-to-Nernstian sensitivity, sufficient stability and resiliency to skin penetration guarantee the sensor's success in transdermal measurements, which we demonstrate through ex vivo (with pieces of rat skin) and in vivo (on-body measurements in rats) tests. Accuracy is evaluated by comparison with gold standard techniques to characterize collected dermal fluid, blood, and serum. In the past, interstitial fluid (ISF) analysis has been challenging due to difficult sample collection and analysis. For ions, this has resulted in extrapolations from blood concentrations (invasive tests) rather than pure measurements in ISF. The developed microneedle patch is a relevant analytical tool to address this information gap.
Topics: Rats; Animals; Potentiometry; Skin; Electrodes; Needles; Ions
PubMed: 36475628
DOI: 10.1021/acssensors.2c01907 -
Ecotoxicology and Environmental Safety Mar 2024Deferiprone, generally, is considered an important chelating agent for Fe overload. From a literature data analysis, a lack of information on the interaction of this...
Deferiprone, generally, is considered an important chelating agent for Fe overload. From a literature data analysis, a lack of information on the interaction of this molecule toward a series of metal cations emerged, inducing to fill out the topic. The complexing ability of deferiprone toward Ca, Mg, Cd and Pb was studied by potentiometry and H NMR spectroscopy, in KCl aqueous solutions at different ionic strength values (0.1 ≤ I/mol dm ≤ 1.0) and T = 298.15 K. The same speciation model featured by the ML, ML, ML and ML(OH) (M = metal and L = deferiprone or DFP) species was obtained for Cd and Pb; the formation constants calculated at infinite dilution are: logβ = 7.23±0.02, 12.47±0.03, 16.70±0.04, and -2.53±0.04, respectively for Cd and 9.91±0.01, 15.99±0.02, 19.93±0.05 and 0.99±0.02 for Pb. Only two species, namely ML and ML, were determined for Ca and Mg, whose formation constants at infinite dilution are respectively: 3.72±0.01 and 6.50±0.02, for the first one, 5.31±0.01 and 9.58±0.01, for the second. The ligand sequestering ability and affinity toward M were evaluated by determining the pL and pM parameters at different pHs and ionic strengths. The results suggest that deferiprone has the best complexing and sequestering ability toward Pb, followed by Cd, Mg and Ca, respectively. H NMR studies confirmed the DFP affinity for Cd and Pb, and in combination with DFT calculations showed that metal cations are bound to the hydroxo-oxo moiety of the pyridinone ring. The data reported in this study provide information on the possible employment of a small molecule like deferiprone, as a chelating and sequestering agent for Pb accumulation or overload from environmental and biological matrices.
Topics: Deferiprone; Cadmium; Lead; Cations; Models, Theoretical; Chelating Agents
PubMed: 38295733
DOI: 10.1016/j.ecoenv.2024.116027 -
Sensors (Basel, Switzerland) Dec 2022The evaluation of the biogenic amines (BAs) profile of different types of craft beers is herein presented. A previously developed and validated analytical method based...
The evaluation of the biogenic amines (BAs) profile of different types of craft beers is herein presented. A previously developed and validated analytical method based on ion-pair chromatography coupled with potentiometric detection was used to determine the presence of 10 BAs. Good analytical features were obtained for all amines regarding linearity (R values from 0.9873 ± 0.0015 to 0.9973 ± 0.0015), intra- and inter-day precision (RSD lower than 6.9% and 9.7% for beer samples, respectively), and accuracy (recovery between 83.2-108.9%). Detection and quantification limits range from 9.3 to 60.5 and from 31.1 to 202.3 µg L, respectively. The validated method was applied to the analysis of four ale beers and one lager craft beer. Ethylamine, spermidine, spermine, and tyramine were detected in all analyzed samples while methylamine and phenylethylamine were not detected. Overall, pale ale beers had a significantly higher total content of BAs than those found in wheat pale and dark samples. A general least square regression model showed a good correlation between the total content of BAs and the brewing process, especially for Plato degree, mashing, and fermentation temperatures. Knowledge about the type of ingredients and manufacturing processes that contribute to higher concentrations of these compounds is crucial to ensuring consumer safety.
Topics: Beer; Biogenic Amines; Chromatography, High Pressure Liquid; Spermidine; Spermine
PubMed: 36616940
DOI: 10.3390/s23010343