Comparative analysis of electrochemical and optical sensors for detection of chronic wounds biomarkers: A review

Chronic wounds (CW) present a significant healthcare challenge due to their prolonged healing time and associated complications. To effectively treat these wounds and prevent further deterioration, monitoring their healing progress is crucial. Traditional wound assessment methods relying on visual inspection and subjective evaluation are prone to inter-observer variability. Biomarkers play a critical role in objectively evaluating wound status and predicting healing outcomes, providing quantitative measures of wound healing progress, inflammation, infection, and tissue regeneration. Recent attention has been devoted to identifying and validating CW biomarkers. Various studies have investigated potential biomarkers, including growth factors, cytokines, proteases, and extracellular matrix components, shedding light on the complex molecular and cellular processes within CW. This knowledge enables a more targeted and personalized approach to wound management. Accurate and sensitive techniques are necessary for detecting CW biomarkers. Thus, this review compares and discusses the use of electrochemical and optical sensors for biomarker determination. The advantages and disadvantages of these sensors are highlighted. Differences in detection capabilities and characteristics such as non-invasiveness, portability, high sensitivity, specificity, simplicity, cost-effectiveness, compatibility with point-of-care applications, and real-time monitoring of wound biomarkers will be pointed out and compared. In summary, this work provides an overview of CW, explores the emerging field of CW biomarkers, and discusses methods for detecting these biomarkers, with a specific focus on optical and electrochemical sensors. The potential of further research and development in this field for advancing wound care and improving patient outcomes will also be noted.

Fluoroquinolone-Based Organic Salts (GUMBOS) with Antibacterial Potential

Antimicrobial resistance is a silent pandemic considered a public health concern worldwide. Strategic therapies are needed to replace antibacterials that are now ineffective. One approach entails the use of well-known antibacterials along with adjuvants that possess non-antibiotic properties but can extend the lifespan and enhance the effectiveness of the treatment, while also improving the suppression of resistance. In this regard, a group of uniform materials based on organic salts (GUMBOS) presents an alternative to this problem allowing the combination of antibacterials with adjuvants. Fluoroquinolones are a family of antibacterials used to treat respiratory and urinary tract infections with broad-spectrum activity. Ciprofloxacin and moxifloxacin-based GUMBOS were synthesized via anion exchange reactions with lithium and sodium salts. Structural characterization, thermal stability and octanol/water partition ratios were evaluated. The antibacterial profiles of most GUMBOS were comparable to their cationic counterparts when tested against Gram-positive S. aureus and Gram-negative E. coli, except for deoxycholate anion, which demonstrated the least effective antibacterial activity. Additionally, some GUMBOS were less cytotoxic to L929 fibroblast cells and non-hemolytic to red blood cells. Therefore, these agents exhibit promise as an alternative approach to combining drugs for treating infections caused by resistant bacteria.

Automatic Identification of Myeloperoxidase Natural Inhibitors in Plant Extracts

The aim of this study is the development of an automated method for myeloperoxidase activity evaluation and its application in testing the inhibitory action of different plant extracts on the activity of the enzyme. This enzyme has its concentration increased in inflammatory and infectious processes, so it is a possible target to limit these processes. Therefore, an automatic sequential in-jection analysis (SIA) system was optimized and demonstrated that it is possible to obtain results with satisfactory accuracy and precision. With the developed method, plant extracts were studied, as promising candidates for MPO inhibition. In the group of selected plant extracts, IC50 values from 0.029 ± 0.002 mg/mL to 35.4 ± 3.5 mg/mL were obtained. Arbutus unedo L. proved to be the most inhibitory extract for MPO based on its phenolic compound content. The coupling of an automatic SIA method to MPO inhibition assays is a good alternative to other conventional methods, due to its simplicity and speed. This work also supports the pharmacological use of these species that inhibit MPO, and exhibit activity that may be related to the treatment of infection and inflammation.

Microsequential injection analysis/lab-on-valve system for the automatic evaluation of acetylcholinesterase inhibitors

A miniaturized microsequential injection/lab-on-valve (µSIA-LOV) system was developed and shown to be a useful alternative to perform inhibitory studies on acetylcholinesterase. These studies are essential for the evaluation of the potential therapeutic effect of drugs commonly used in the treatment of Alzheimer's disease. Donepezil, galantamine, and rivastigmine were tested, in addition to compounds based on the xanthone scaffold. Four of these xanthone derivatives were identified as having EC₅₀ values between 676 and 4466 µmol/l, showing a potential inhibitory effect higher than the clinical agent rivastigmine. The developed automatic system added advantages of reduction of reagents and sample consumption (around 55 µl per analysis), lower cost per analysis, and the generation of less waste (around 1.2 ml per analysis). The µSIA-LOV system is also a robust, rapid, reliable, and simple system to use. Docking studies suggested a possible mode of interaction with the target acetylcholinesterase protein.

Immobilized imidazolium-based ionic liquids in C18 for solid-phase extraction

In this work, two solid-phases based on imidazolium-based ionic liquids were obtained and characterized for solid-phase extraction of fluoroquinolones. The process of immobilization was performed replacing a toxic reagent by UV-irradiation to get a harmless process. The obtained solid-phases were characterized by nuclear magnetic resonance spectroscopy and elemental analysis. Each solid-phase was packed in a cartridge and was used in solid-phase extraction processes for norfloxacin and ciprofloxacin, after the optimization of some parameters such as the elution solvent, the eluent volume and, the sample volume to be used during the loading step. The developed solid-phases with immobilized ionic liquids were successfully implemented for the studied compounds and indicate high probabilities to be useful in solid-phase extractions of other fluoroquinolones.

Automatic fluorometric lactate determination in human plasma samples

A new automatic, robust, economic and reliable methodology to determine the lactate levels in human plasma in a fast way and using low volume blood samples.

Enzymatic Reactions in a Lab-on-Valve System: Cholesterol Evaluations

The micro sequential injection analysis / lab-on-valve (µSIA-LOV) system is a miniaturized SIA system resulting from the implementation of a lab-on-valve (LOV) atop of the selection valve. It integrates the detection cell and the sample processing channels into the same device, promoting the reduction of reagent consumption and waste generation, the improvement of the versatility, and the reduction of the time of analysis. All of these characteristics are really relevant to the implementation of enzymatic reactions. Additionally, the evaluation of cholesterol in serum samples is widely relevant in clinical diagnosis, since higher values of cholesterol in human blood are actually an important risk factor for cardiovascular problems. An automatic methodology was developed based on the µSIA-LOV system in order to evaluate its advantages in the implementation of enzymatic reactions performed by cholesterol esterase, cholesterol oxidase and peroxidase. Considering these reactions, the developed methodology was also used for the evaluation of cholesterol in human serum samples, showing reliable and accurate results. The developed methodology presented detection and quantification limits of 1.36 and 4.53 mg dL⁻¹ and a linear range up to 40 mg dL⁻¹. This work confirmed that this µSIA-LOV system is a simple, rapid, versatile, and robust analytical tool for the automatic implementation of enzymatic reactions performed by cholesterol esterase, cholesterol oxidase, and peroxidase. It is also a useful alternative methodology for the routine determinations of cholesterol in real samples, even when compared with other automatic methodologies.

Manual or automated measuring of antipsychotics' chemical oxygen demand

Antipsychotic (AP) drugs are becoming accumulated in terrestrial and aqueous resources due to their actual consumption. Thus, the search of methods for assessing the contamination load of these drugs is mandatory. The COD is a key parameter used for monitoring water quality upon the assessment of the effect of polluting agents on the oxygen level. Thus, the present work aims to assess the chemical oxygen demand (COD) levels of several typical and atypical antipsychotic drugs in order to obtain structure-activity relationships. It was implemented the titrimetric method with potassium dichromate as oxidant and a digestion step of 2h, followed by the measurement of remained unreduced dichromate by titration. After that, an automated sequential injection analysis (SIA) method was, also, used aiming to overcome some drawbacks of the titrimetric method. The results obtained showed a relationship between the chemical structures of antipsychotic drugs and their COD values, where the presence of aromatic rings and oxidable groups give higher COD values. It was obtained a good compliance between the results of the reference batch procedure and the SIA system, and the APs were clustered in two groups, with the values ratio between the methodologies, of 2 or 4, in the case of lower or higher COD values, respectively. The SIA methodology is capable of operating as a screening method, in any stage of a synthetic process, being also more environmentally friendly, and cost-effective. Besides, the studies presented open promising perspectives for the improvement of the effectiveness of pharmaceutical removal from the waste effluents, by assessing COD values.

The role of ionic liquids in the biocatalytic evaluation of bisphenol levels as contaminant: an automatic approach

Automation of peroxidase activity evaluation and bisphenol A quantification in ionic liquids medium.

Biodegradability of several antipsychotic drugs: manual and automatic assessment

For the first time, the biodegradability values were determined for several antipsychotic drugs.

Assessment of ionic liquids' toxicity through the inhibition of acylase I activity on a microflow system

Acylase I (ACY I) plays a role in the detoxication and bioactivation of xenobiotics as well in other physiological functions. In this context, an automated ACY I assay for the evaluation of ionic liquids' (ILs) toxicity was developed. The assay was implemented in a sequential injection analysis (SIA) system and was applied to eight commercially available ILs. The SIA methodology was based on the deacetylation of N-acetyl-l-methionine with production of l-methionine, which was determined using fluorescamine. ACY I inhibition in the presence of ILs was monitored by the decrease of fluorescence intensity. The obtained results confirmed the influence of ILs' structural elements on its toxicity and revealed that pyridinium and phosphonium cations, longer alkyl side chains and tetrafluoroborate anion displayed higher toxic effect on enzyme activity. The developed methodology proved to be robust and exhibited good repeatability (RSD < 1.3%, n = 10), leading also to a reduction of reagents consumption and effluents production. Thus, it is expected that the proposed assay can be used as a novel tool for ILs' toxicity screening.

Automated evaluation of the inhibition of glutathione reductase activity: application to the prediction of ionic liquids' toxicity

An automated bioassay based on glutathione reductase was developed and applied to the evaluation of the toxicity of ionic liquids.

Silica nanostructures synthesis and CdTe quantum dots immobilization for photocatalytical applications

A new strategy for the immobilization of semiconductor nanocrystals by carrying out in simultaneous the biomimetic synthesis of silica nanostructures and the encapsulation of MPA-capped CdTe quantum dots (QDs).

Estimation of postmortem interval by hypoxanthine and potassium evaluation in vitreous humor with a sequential injection system

The estimation of the time since death known as postmortem interval (PMI) is a main issue in the field of forensic science and legal medicine. In this work it is proposed a sequential injection system for the determination of hypoxanthine and potassium in the same sample of vitreous humor since the concentrations of both parameters change with PMI and the vitreous humor has been regarded as the ideal extracellular fluid for these kinds of determinations. By measuring both parameters the accuracy of estimation of PMI can be increased, and the effects of factors which influence the values in postmortem chemistry minimized. Hypoxanthine determination is based on its oxidation to uric acid (290 nm), catalyzed by immobilized xanthine oxidase, and the quantification of potassium levels in vitreous humor was performed using a tubular potassium ion-selective electrode. With a unique analytical cycle both analytes were evaluated being potassium levels determined during the degradation of hypoxanthine in the enzymatic reactor. Working concentration ranges between 6.04-40.00 micromol L(-1) and 7.00 x 10(-5) to 1.00 x 10(-1)mmol L(-1) were obtained, for hypoxanthine and potassium, respectively. The method proved to be reproducible with R.S.D. <5% for hypoxanthine and <3% for potassium. Sampling rate was approximately 30 per hour for the sequential determination of both parameters being 15 and 60 determinations per hour if hypoxanthine or potassium, where evaluated independently. Statistical evaluation at the 95% confidence level showed good agreement between the results obtained, for the vitreous humor samples, with both the SIA system and the comparison batch procedures. Moreover the methodology has low environmental impact in agreement with the demands of green analytical chemistry as only 2.7 mL of chemical waste is produced during both determinations.

Application of Sequential Injection Analysis to the Determination of Cationic Surfactants Based on the Sensitized Molybdenum-Bromopyrogallol Red Reaction

The aim of this work was to develop a simple, automatic system for the evaluation of cationic surfactants by combining sequential injection analysis and the sensitized effect of cationic surfactants on the reaction between metal ions and chelating dyes. This reaction is based on the increase in absorbance of the complex formed among molybdenum, bromopyrogallol red and increasing concentrations of cationic surfactants. Under optimum conditions, two calibration plots were obtained for a concentration range between 2.50 x 10(-7) mol dm(-3) (detection limit) and 5.00 x 10(-4) mol dm(-3) of cetylpyridinium chloride, used as standard. Solubilization of water insoluble complexes formed for concentrations of cationic surfactants greater than 1.00 x 10(-4) mol dm(-3) were successfully achieved with Triton X-405. RSD values lower than 5.0% were obtained in all cases. The quality of the results obtained for 18 water samples were evaluated by comparison with conventional methods, with no statistically significant differences for a 95% confidence level.