A colour sensor integrated into a microcontroller platform as a reliable tool for measuring pH changes in biochemistry applications.

Colorimetry is a widely used technique for optical detection in point-of-care testing and on-site detection. Although some studies employ a multiplex approach to analyse coloured solutions, many still analyse one sample at a time. We have prepared a simple and affordable colorimetric assay based on a TCS34725 colour sensor (ams-OSRAM) integrated into an M5Stack module and an RGB LED module both inserted into a 3D printed frame. We found that the colorimetric assay can be easily transferred to a colour sensing platform, and the signal range obtained using the prepared colorimeter is more than 200 times larger than that obtained using digital image colorimetry (DIC) for the same samples containing cholinesterase or urease as a model enzyme providing a change in pH of the processed solution. The assay appears to be ready for practical use.

Biosensors and Bioassays for the Medical Detection of Bacillus Anthracis and Diagnosis of Anthrax.

Bacillus anthracis is a causative agent of the highly mortal disease anthrax. This zoonosis is present in nature, but it is also considered one of the most powerful biological warfare agents. A timely diagnosis is necessary for proper therapy and setting of epidemiological countermeasures. Current diagnostic methods should be used in specialized laboratories or medical facilities because there are only a limited number of methods suitable as hand-held assays or even point-of-care tests for detecting B. anthracis or anthrax diagnosis. The lateral flow tests are an exception in this regard, but these tests also have some limitations. Significant progress has been achieved in point-of-care tests for B. anthracis detection and anthrax diagnosis in various biosensors and bioassays. This review focuses on current hand-held and point-of-care tests that can easily prove anthrax or its causative agent outside the context of specialized facilities.

A 3D-Printed Do-It-Yourself ELISA Plate Reader as a Biosensor Tested on TNFα Assay.

Simple analytical devices suitable for the analysis of various biochemical and immunechemical markers are highly desirable and can provide laboratory diagnoses outside standard hospitals. This study focuses on constructing an easily reproducible do-it-yourself ELISA plate reader biosensor device, assembled from generally available and inexpensive parts. The colorimetric biosensor was based on standard 96-well microplates, 3D-printed parts, and a smartphone camera as a detector was utilized here as a tool to replace the ELISA method, and its function was illustrated in the assay of TNFα as a model immunochemical marker. The assay provided a limit of detection of 19 pg/mL when the B channel of the RGB color model was used for calibration. The assay was well correlated with the ELISA method, and no significant matrix effect was observed for standard biological samples or interference of proteins expected in a sample. The results of this study will inform the development of simple analytical devices easily reproducible by 3D printing and found on generally available electronics.

Are there Risks from Nanocomposite Restoration Grinding for Dentists?

OBJECTIVES: To evaluate the effect of short-term inhalational exposure to nanoparticles released during dental composite grinding on oxidative stress and antioxidant capacity markers. MATERIALS AND METHODS: Twenty-four healthy volunteers were examined before and after exposure in dental workshop. They spent 76.8 ± 0.7 min in the testing room during grinding of dental nanocomposites. The individual exposure to aerosol particles in each participant´s breathing zones was monitored using a personal nanoparticle sampler (PENS). Exhaled breath condensate (EBC), blood, and urine samples were collected pre- and post-exposure to measure one oxidative stress marker, i.e., thiobarbituric acid reactive substances (TBARS), and two biomarkers of antioxidant capacity, i.e., ferric-reducing antioxidant power (FRAP) and reduced glutathione (GSH) by spectrophotometry. Spirometry and fractional exhaled nitric oxide (FeNO) were used to evaluate the effect of acute inhalational exposure. RESULTS: Mean mass of dental nanocomposite ground away was 0.88 ± 0.32 g. Average individual doses of respirable particles and nanoparticles measured by PENS were 380 ± 150 and 3.3 ± 1.3 µg, respectively. No significant increase of the post-exposure oxidative stress marker TBARS in EBC and plasma was seen. No decrease in antioxidant capacity biomarkers FRAP and GSH in EBC post-exposure was seen, either. Post-exposure, conjunctival hyperemia was seen in 62.5% volunteers; however, no impairment in spirometry or FeNO results was observed. No correlation of any biomarker measured with individual exposure was found, however, several correlations with interfering factors (age, body mass index, hypertension, dyslipidemia, and environmental pollution parameters) were seen. CONCLUSIONS: This study, using oxidative stress biomarker and antioxidant capacity biomarkers in biological fluids of volunteers during the grinding of dental nanocomposites did not prove a negative effect of this intense short-term exposure. However, further studies are needed to evaluate oxidative stress in long-term exposure of both stomatologists and patients and diverse populations with varying health statuses.

Open Meter Duo: Low-Cost Instrument for Fluorimetric Determination of Cholinesterase Activity.

Environmental screening is essential due to the increased occurrence of harmful substances in the environment. Open Meter Duo (OMD) is an open-source field photo/fluorimeter that uses an RGB diode that imitates a color according to the selected wavelength and uses a UV LED from the security kit diode as an excitation light source. The prepared PCB shield with a 3D-printed aperture was connected to Arduino UNO R4 WiFi. This system was used for the fluorescent detection of cholinesterase activity with the indoxyl acetate method. Carbofuran-a toxic pesticide-and donepezil-a drug used to treat Alzheimer's disease-were tested as model inhibitors of cholinesterase activity. The limit of detection of indoxyl acetate was 11.6 µmol/L, and the IC50 values of the inhibitors were evaluated. This system is optimized for wireless use in field analysis with added cloud support and power source. The time of analysis was 5 min for the fluorimetric assay and 20 min for the optional photometric assay. The time of field operation was approximately 4 h of continuous measurement. This system is ready to be used as a cheap and easy control platform for portable use in drug control and point-of-care testing.

Urine Test Strip Quantitative Assay with a Smartphone Camera.

Urine test strips for urinalysis are a common diagnostic tool with minimal costs and are used in various situations including homecare and hospitalization. The coloration scaled by the naked eye is simple, but it is suitable for semiquantitative analysis only. In this paper, a colorimetric assay is developed based on a smartphone digital camera and urine test strips. Assays of pH, albumin, glucose, and lipase activity were performed as a tool for the diagnosis of aciduria, alkaluria, glycosuria, proteinuria, and leukocyturia. The RGB color channels were analyzed in the colorimetric assay, and the assay exerted good sensitivity, and all the particular diagnoses proved to be reliable. The limits of detection for glucose (0.11 mmol/L), albumin (0.15 g/L), and lipase (2.50 U/µL) were low enough to cover the expected physiological concentration, and the range for pH was also satisfactory. The urine test strips with a camera as an output detector proved applicability to spiked urine samples, and the results were also well in comparison to the standard assays which confirms the practical relevance of the presented findings.

Oxidative stress, microparticles, and E-selectin do not depend on HIV suppression.

BACKGROUND: Oxidative stress and inflammation are considered predictors of diseases associated with aging. Markers of oxidative stress, inflammation, and endothelial activation were investigated in people with HIV on antiretroviral treatment to determine whether they had an immunosenescent phenotype that might predispose to the development of premature age-related diseases. PATIENTS AND METHODS: This study was conducted on 213 subjects with HIV. The control groups consisted of healthy HIV-negative adults. The level of oxidative stress was measured by assessing the production of malondialdehyde levels, which were detected by thiobarbituric acid reactive substance (TBARS) assay. The level of microparticles indicated the presence of inflammation and endothelial activation was measured by E-selectin levels. Significant differences were determined by appropriate statistical tests, depending on the distribution of variables. Relationships between continuous variables were quantified using Spearman's rank correlation coefficient. RESULTS: TBARS, and microparticle and E-selectin levels were significantly higher in untreated and treated subjects with HIV compared with HIV-negative controls (P<0.001). The levels of the investigated markers were not significantly different between untreated and treated patients and no significant correlation of these markers was found with CD4+ count, CD4+/CD8+ ratio, and the number of HIV-1 RNA copies. CONCLUSIONS: Elevated markers of oxidative stress, inflammatory and endothelial activation were independent of the virologic and immunologic status of people with HIV. These results support the hypothesis that residual viremia in cellular reservoirs of various tissues is a key factor related to the premature aging of the immune system and predisposition to the premature development of diseases associated with aging.

Elevated glutathione in researchers exposed to engineered nanoparticles due to potential adaptation to oxidative stress.

Aim: To find a practical biomonitoring method for researchers exposed to nanoparticles causing oxidative stress. Methods: In a continuation of a study in 2016-2018, biological samples (plasma, urine and exhaled breath condensate [EBC]) were collected in 2019-2020 from 43 researchers (13.8 ± 3.0 years of exposure) and 45 controls. Antioxidant status was assessed using glutathione (GSH) and ferric-reducing antioxidant power, while oxidative stress was measured as thiobarbituric acid reactive substances, all using spectrophotometric methods. Researchers' personal nanoparticle exposure was monitored. Results: Plasma GSH was elevated in researchers both before and after exposure (p < 0.01); postexposure plasma GSH correlated with nanoparticle exposure, and GSH in EBC increased. Conclusion: The results suggest adaptation to chronic exposure to nanoparticles, as monitored by plasma and EBC GSH.

What is this study about? Identifying markers of oxidative stress and/or adaptation to oxidation stress could offer tools for monitoring exposure to nanoparticles in exposed researchers. In this study, we question whether these markers correlate with their personal exposure during the shift. What were the results? We found that exposure to nanoparticles correlated with the antioxidant marker glutathione, which is higher in workers who are already pre-exposed. What do the results mean? This study suggests that the researchers have adapted to nanoparticle exposure and are ready to combat oxidative stress. However, the similarity with increased markers of oxidative stress from asbestos and silica exposure, including nucleic acid oxidation, previously found in these researchers highlights the need for further research in this area to better understand and prevent potential future effects.

Current trends in digital camera-based bioassays for point-of-care tests.

Point-of-care and bedside tests are analytical devices suitable for a growing role in the current healthcare system and provide the opportunity to achieve an exact diagnosis by an untrained person and in various conditions and sites where it is necessary. Using a digital camera integrated into a well-accessible device like a smartphone brings a new way in which a colorimetric point-of-care diagnostic test can provide unbiased data. This review summarizes basic facts about the colorimetric point-of-care tests, principles of how to use a portable device with a camera in the assay, applications of digital cameras for the current tests, and new devices described in the recent papers. An overview of the recent literature and a discussion of recent developments and future trends are provided.

Pharmacology and toxicology of kratom.

The term kratom is commonly used for both Mitragyna speciosa and herbal products prepared mainly from leaves. Kratom is well known as a drug that can serve as a less toxic and less-addictive pain-relieving substitute for opium, as well as a therapy for hypertension, cough, and diarrhea. Its major alkaloid, mitragynine, also deserves concern. However, most people use kratom as a psychological stimulant, which carries a risk of addiction associated with negative social and health impacts. This paper reviews basic facts about kratom and its potential use in pharmacology, pharmacokinetics, and pharmacokinetics of its major alkaloid mitragynine (Tab. 3, Fig. 1, Ref. 87). Keywords: 7-hydroxymitragynine; alkaloid; anesthetics; antitussive; drug; mitragynine; Mitragyna speciosa; addictive substance; opioid receptor.

Affordable Portable Platform for Classic Photometry and Low-Cost Determination of Cholinesterase Activity.

Excessive use of pesticides could potentially harm the environment for a long time. The reason for this is that the banned pesticide is still likely to be used incorrectly. Carbofuran and other banned pesticides that remain in the environment may also have a negative effect on human beings. In order to provide a better chance for effective environmental screening, this thesis describes a prototype of a photometer tested with cholinesterase to potentially detect pesticides in the environment. The open-source portable photodetection platform uses a color-programmable red, green and blue light-emitting diode (RGB LED) as a light source and a TSL230R light frequency sensor. Acetylcholinesterase from Electrophorus electricus (AChE) with high similarity to human AChE was used for biorecognition. The Ellman method was selected as a standard method. Two analytical approaches were applied: (1) subtraction of the output values after a certain period of time and (2) comparison of the slope values of the linear trend. The optimal preincubation time for carbofuran with AChE was 7 min. The limits of detection for carbofuran were 6.3 nmol/L for the kinetic assay and 13.5 nmol/L for the endpoint assay. The paper demonstrates that the open alternative for commercial photometry is equivalent. The concept based on the OS3P/OS3P could be used as a large-scale screening system.

Immunosensors for Assay of Toxic Biological Warfare Agents.

An immunosensor for the assay of toxic biological warfare agents is a biosensor suitable for detecting hazardous substances such as aflatoxin, botulinum toxin, ricin, Shiga toxin, and others. The application of immunosensors is used in outdoor assays, point-of-care tests, as a spare method for more expensive devices, and even in the laboratory as a standard analytical method. Some immunosensors, such as automated flow-through analyzers or lateral flow tests, have been successfully commercialized as tools for toxins assay, but the research is ongoing. New devices are being developed, and the use of advanced materials and assay techniques make immunosensors highly competitive analytical devices in the field of toxic biological warfare agents assay. This review summarizes facts about current applications and new trends of immunosensors regarding recent papers in this area.

Quartz crystal microbalance biosensor for the detection of procalcitonin.

Procalcitonin is a blood protein and precursor of the hormone calcitonin. The procalcitonin level increases due to bacterial infections, sepsis, and other related pathologies. Here, we present a simple biosensor for procalcitonin assay suitable for point-of-care tests as an alternative to the current laboratory methods. The biosensor was based on a QCM piezoelectric sensor and a conjugate of gold nanoparticles-antibodies conjugate. It was suitable for the procalcitonin assay in biological samples and fully correlated to the standard ELISA method, and it did not suffer false positive or negative results or interferences. The detection limit was equal to 37.8 ng/l and the quantification limit to 104 ng/l for a sample of 25 µl. The dynamic range of the assay was 37.8 ng/l to 30.0 µg/l. The practical relevance of the biosensor is expected considering the findings, and the possible application of the assay principle for the development of biosensors for other markers is inferred.

Progress in Biosensors for the Point-of-Care Diagnosis of COVID-19.

Coronavirus disease 2019 (COVID-19) is a highly virulent infection that has caused a pandemic since 2019. Early diagnosis of the disease has been recognized as one of the important approaches to minimize the pathological impact and spread of infection. Point-of-care tests proved to be substantial analytical tools, and especially lateral flow immunoassays (lateral flow tests) serve the purpose. In the last few years, biosensors have gained popularity. These are simple but highly sensitive and accurate analytical devices composed from a selective molecule such as an antibody or antigen and a sensor platform. Biosensors would be an advanced alternative to current point-of-care tests for COVID-19 diagnosis and standard laboratory methods as well. Recent discoveries related to point-of-care diagnostic tests for COVID-19, the development of biosensors for specific antibodies and specific virus parts or their genetic information are reviewed.

The latest trends in the design of electrochemical biosensors for the diagnosis and monitoring of diabetes mellitus.

RESULTS: The overworld health problem, the incurable disease, the global burden on health insurers and society, and above all one of the leading causes of death - all characterize diabetes mellitus, a lifelong chronic disease that affects hundreds of millions of people around the world. The new types of biosensors bring new opportunities in the care of diabetic patients and improve current methods. The practical relevance of the recent findings is expected in medicine in next years. CONCLUSIONS: The authors summarized the modern possibilities of biosensing, their pros and cons, and their perspectives for the future. The discussion outcome from the current literature (Tab. 4, Fig. 1, Ref. 63).

Diagnoses Based on C-Reactive Protein Point-of-Care Tests.

C-reactive protein (CRP) is an important part of the immune system's reaction to various pathological impulses such as bacterial infections, systemic inflammation, and internal organ failures. An increased CRP level serves to diagnose the mentioned pathological states. Both standard laboratory methods and simple point-of-care devices such as lateral flow tests and immunoturbidimetric assays serve for the instrumental diagnoses based on CRP. The current method for CRP has many flaws and limitations in its use. Biosensor and bioassay analytical devices are presently researched by many teams to provide more sensitive and better-suited tools for point-of-care tests of CRP in biological samples when compared to the standard methods. This review article is focused on mapping the diagnostical relevance of CRP, the applicability of the current analytical methods, and the recent innovations in the measurement of CRP level.

A Butyrylcholinesterase Camera Biosensor Tested for Carbofuran and Paraoxon Assay.

Biosensors containing cholinesterase are analytical devices suitable for the assay of neurotoxic compounds. In the research on biosensors, a new platform has appeared some years ago. It is the digital photography and scoring of coloration (photogrammetry). In this paper, a colorimetric biosensor is constructed using 3D-printed multiwell pads treated with indoxylacetate as a chromogenic substrate and gold nanoparticles with the immobilized enzyme butyrylcholinesterase. A smartphone camera served for photogrammetry. The biosensor was tested for the assay of carbofuran and paraoxon ethyl as two types of covalently binding inhibitors: irreversible and pseudoirreversible. The biosensor exerted good sensitivity to the inhibitors and was able to detect carbofuran with a limit of detection for carbofuran 7.7 nmol/l and 17.6 nmol/l for paraoxon ethyl. A sample sized 25 µl was suitable for the assay lasting approximately 70 minutes. Up to 121 samples can be measured contemporary using one multiwell pad. The received data fully correlated with the standard spectrophotometry. The colorimetric biosensor exerts promising specifications and appears to be competitive to the other analytical procedures working on the principle of cholinesterase inhibition. Low-cost, simple, and portable design represent an advantage of the assay of the biosensor. Despite the overall simplicity, the biosensor can fully replace the standard spectroscopic methods.

Role of Caffeine in the Age-related Neurodegenerative Diseases: A Review.

Caffeine, a simple purine alkaloid with the proper chemical name 1,3,7-trimethylpurine- 2,6-dione, is an abundant compound present in coffee, food and drugs. It interacts with various pathways of which antagonism of adenosine receptors is the most significant but the other physiological pathways can be influenced by caffeine as well. Interaction with glutamate and dopamine neurotransmission pathways, competition with other substrates on cytochrome P450, non-competitive inhibition of acetylcholinesterase, blocking of nicotinic acetylcholine receptor and competitive inhibition of cyclic nucleotide phosphodiesterase can be mentioned. Because of caffeine availability in foods, beverages and drugs, it has practical relevance even if the effect is weak. Intake of coffee containing edibles for a long period or even for a substantial part of life makes caffeine´s impact significant. Low acute and chronic toxicity of caffeine is another important specification. The discoveries from the last few years point to the fact that caffeine would interfere with the progression of some age-related neurodegenerative disorders like Alzheimer's and Parkinson's diseases and dementia with Lewy bodies. In this review article, the recent findings about caffeine´s impact on neurodegenerative diseases are presented and important facts about the caffeine effect, including the substantial discoveries, are described.

New Uses of Melatonin as a Drug; A Review.

Melatonin is a simple compound called N-acetyl-5-methoxy tryptamine and is known as a hormone controlling the circadian rhythm. Melatonin is produced by the human body naturally. The production of melatonin increases in the evening, causing a state of sleep at night and wakefulness during the day. Melatonin interacts with melatonin receptors MT1 and MT2, but it was revealed that melatonin is a strong antioxidant and it also has a role in the regulation of the cell cycle. Melatonin is now used as a medicine to treat some types of sleep disorders. Moreover, recent research suggests that it can also be utilized for other purposes, such as prevention from chemical exposure and treatment of various diseases, including cancer, neurodegenerative disorders, etc. This review summarizes the basic facts and direction of the current research on melatonin. The existing literature was scrutinized for this review.

Novel Trends in Electrochemical Biosensors for Early Diagnosis of Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) is a multifactorial progressive and irreversible neurodegenerative disorder affecting mainly the population over 65 years of age. It is becoming a global health and socioeconomic problem, and the current number of patients reaching 30-50 million people will be three times higher over the next thirty years. OBJECTIVE: Late diagnosis caused by decades of the asymptomatic phase and invasive and cost-demanding diagnosis are problems that make the whole situation worse. Electrochemical biosensors could be the right tool for less invasive and inexpensive early diagnosis helping to reduce spend sources- both money and time. METHOD: This review is a survey of the latest advances in the design of electrochemical biosensors for the early diagnosis of Alzheimer's disease. Biosensors are divided according to target biomarkers. CONCLUSION: Standard laboratory methodology could be improved by analyzing a combination of currently estimated markers along with neurotransmitters and genetic markers from blood samples, which make the test for AD diagnosis available to the wide public.