The development of point-of-care wearable devices capable of measuring insulin concentration has the potential to significantly improve diabetes management and life quality of diabetic patients. However, the lack of a suitable point-of-care device for personal use makes regular insulin level measurements challenging, in stark contrast to glucose monitoring. Herein, we report an electrochemical transdermal biosensor that utilizes a high-density polymeric microneedle array (MNA) to detect insulin in interstitial fluid (ISF). The biosensor consists of gold-coated polymeric MNA modified with an insulin-selective aptamer, which was used for extraction and electrochemical quantification of the insulin in ISF. In vitro testing of biosensor, performed in artificial ISF (aISF), showed high selectivity for insulin with a linear response between 0.01 nM and 4 nM (sensitivity of ∼65 Ω nM-1), a range that covers both the physiological and the pathological concentration range. Furthermore, ex vivo extraction and quantification of insulin from mouse skin showed no impact on the biosensor's linear response. As a proof of concept, an MNA-based biosensing platform was utilized for the extraction and quantification of insulin on live mouse skin. In vivo application showed the ability of MNs to reach ISF, extract insulin from ISF, and perform electrochemical measurements sufficient for determining insulin levels in blood and ISF. We believe that our MNA-based biosensing platform based on extraction and quantification of the biomarkers will help move insulin assays from traditional laboratory approaches to personalized point-of-care settings.

Microneedles (MNs) or microneedle arrays (MNAs) are critical components of minimally invasive devices comprised of a single or a series of micro‐scale projections. MNs can bypass the outermost layer of the skin and painlessly access microcirculation of the epidermis and dermis layers, attracting great interest in the development of personalized healthcare monitoring and diagnostic devices. However, MN technology has not yet reached its full potential since current micro‐ and nanofabrication methods do not address the need of fabricating MNs with complex surfaces to facilitate the development of clinically adequate devices. This work presents a new approach that combines 3D printing technology based on two‐photon polymerization with soft lithography for cost‐effective and time‐saving fabrication of complex MNAs. Specifically, this method relies on printing complex 3D objects efficiently replicated into polymeric substrates via soft lithography, resulting in a free‐standing polymeric lattice (PL) membrane that can be transferred onto gold‐coated MNs and used for electrochemical biosensing. This platform shows excellent electrochemical performance in detecting metabolite (glucose) and protein (insulin) biomarkers with a dynamic linear range sufficient for detecting biomarkers in healthy individuals and patients. The approach holds great potential for fabricating next‐generationMNs, including their transfer into clinically adequate devices.

Microneedle-based wearable electrochemical biosensors are the new frontier in personalized health monitoring and disease diagnostic devices that provide an alternative tool to traditional blood-based invasive techniques. Advancements in micro- and nanofabrication technologies enabled the fabrication of microneedles using different biomaterials and morphological features with the aim of overcoming existing challenges and enhancing sensing performance. In this work, we report a microneedle array featuring conductive recessed microcavities for monitoring urea levels in the interstitial fluid of the skin. Microcavities are small pockets on the tip of each microneedle that can accommodate the sensing layer, provide protection from delamination during skin insertion or removal, and position the sensing layer in a deep layer of the skin to reach the interstitial fluid. The wearable urea patch has shown to be highly sensitive and selective in monitoring urea, with a sensitivity of 2.5 mV mM-1 and a linear range of 3 to 18 mM making it suitable for monitoring urea levels in healthy individuals and patients. Our ex vivo experiments have shown that recessed microcavities can protect the sensing layer from delamination during skin insertion and monitor changing urea levels in interstitial fluid. This biocompatible platform provides alternative solutions to the critical issue of maintaining the performance of the biosensor upon skin insertion and holds great potential for advancing transdermal sensor technology.

Microneedle-based wearable sensors offer an alternative approach to traditional invasive blood-based health monitoring and disease diagnostics techniques. Instead of blood, microneedle-based sensors target the skin interstitial fluid (ISF), in which the biomarker type and concentration profile resemble the one found in the blood. However, unlike blood, interstitial fluid does not have the same pH-buffering capacity causing deviation of pH levels from the physiological range. Information about the skin ISF pH levels can be used as a biomarker for a wide range of pathophysiological conditions and as a marker for the calibration of a wearable sensor. The ISF pH can significantly affect the detection accuracy of other biomarkers as it influences enzyme activity, aptamer affinity, and antibody-antigen interaction. Herein, we report the fabrication of a high-density polymeric microneedle array-based (PMNA) sensing patch and its optimization for the potentiometric transdermal monitoring of pH levels in ISF. The wearable sensor utilizes a polyaniline-coated PMNA having a density of ∼10,000 microneedles per cm2, containing individual microneedles with a height of ∼250 μm, and a tip diameter of ∼2 μm. To prevent interference from other body fluids like sweat, an insulating layer is deposited at the base of the PMNA. The wearable pH sensor operates from pH 4.0 to 8.6 with a sensitivity of 62.9 mV per pH unit and an accuracy of ±0.036 pH units. Furthermore, testing on a mouse demonstrates the ability of the PMNA to provide a real-time reading of the transdermal pH values. This microneedle-based system will significantly contribute to advancing transdermal wearable sensors technology, simplifying the fabrication process, and improving the cost-effectiveness of such devices.

Wearable technologies have great potential in health monitoring and disease diagnostics. As a consequence, interest in the study of wearable sensors has dramatically increased over recent years. Successful translation of this technology from research prototypes to commercial products requires addressing some of the major challenges faced by wearable sensors such as loss of, and damage in, the biological recognition layer of the skin-interfaced sensors. In this work, we propose a solution to this challenge by integrating micropillar array (MPA) surfaces as part of the sensing layer with the aim to protect and prevent the loss of the enzyme layer from mechanical stress while the sensor is worn. The proposed wearable sensing patch is composed of reference, counter, and working electrodes, all made of MPAs and is designed for measuring glucose in sweat. MPA sensing patch has a wide linear range of 50 μM to 1.4 mM, a sensitivity of 4.7 ± 0.8 μA mM-1, and a limit of detection of 26 ± 5 μM. The glucose sensing patch was tested using human sweat where glucose-level changes were successfully measured before and after meal consumption. The developed patch provides an alternative solution to the problem of the damage to the sensor microenvironment upon wear. But in addition, it also offers a user-friendly, cost-effective, and reliable sweat analysis platform with significant potential in health monitoring applications.

Stray dogs may be highly exposed to vector-borne pathogens (VBPs), including zoonotic agents, and therefore may pose a high risk of spreading infections to other animals and humans. Among the Anaplasmataceae, Anaplasma phagocytophilum, A. platys and Ehrlichia canis are commonly identified species in dogs in Europe; however, information on the occurrence of these pathogens in canine populations from Bosnia and Herzegovina (B&H) is still lacking. Thus, the aim of this study was to determine the seroprevalence of Anaplasma spp. and Ehrlichia spp. in stray dogs in the Sarajevo region of B&H and to identify A. phagocytophilum, A. platys, E. canis and E. ewingii by molecular techniques. A total of 903 blood samples of stray dogs were screened by SNAP 4Dx Plus Test for the presence of antibodies against A. phagocytophilum/A. platys and E. canis/E. ewingii. Real-time PCR assays were performed for the detection of Anaplasmataceae, A. phagocytophilum, A. platys, E. canis and E. ewingii in seropositive dogs. Antibodies to A. phagocytophilum/A. platys and/or E. canis/E. ewingii were detected in 187 (20.7%) samples. Seroprevalence was highest for A. phagocytophilum/A. platys (184/903, 20.4%). Two dogs had antibodies to E. canis/E. ewingii, while one dog was found to have antibodies to A. phagocytophilum/A. platys and to E. canis/E. ewingii. Forty-eight (25.7%) of the 187 seropositive dogs examined by Real-time PCR were positive for Anaplasmataceae. A. phagocytophilum was detected in 45 (24%) samples, while one sample was positive for A. phagocytophilum and A. platys. Two samples positive for Anaplasmataceae tested negative in the species-specific PCRs. E. canis or E. ewingii could not be detected in any of the Ehrlichia-seropositive dogs. These findings highlight the need for dog health monitoring, improving the health and welfare of stray dog population, and establishment of effective surveillance systems to combat VBDs.

The SARS-CoV-2 (COVID-19) pandemic has emerged as one of the greatest problems of the 21st century worldwide. Efforts to fight this pandemic require a global co-operation and a multidisciplinary approach. An application of information and communication technologies (ICT) to a great degree contributes to fighting the pandemic as these technologies are one of the key services that assist patients, researchers, health institutions and other interested parties in different activities in an effort to fight the pandemic and its consequences. The present paper presents the features of certain mobile applications (apps) that are being used for different purposes such as: tracking patients, COVID-19-related warnings, keeping tracks of statistical data, organising life and business, etc. Aside from presenting the features of a certain number of applications, a review of technologies used for the development of these applications will also be presented. Furthermore, the paper addresses certain challenges that come along with the mobile technologies applications and offers suggestions for future research.

Dairy cattle breeding is one of the most important branches of livestock production, which has been facing, for several decades, the chronic problem of declining reproductive performance. In 2005, the number of cattle worldwide was about 1,370,000,000, while in 2015 that number dropped below one billion, and in 2021 it shows a slight recovery as it was 1,000,970. This indicates the importance of applying different reproductive protocols in order to increase the number of cows in production. The type of bedding on which the animals stay, as well as the characteristics of the lying area itself, shows a significant impact on numerous physiological functions such as food intake, chewing, milk yield, but also levels of sex hormones. The type of bedding and lying area, which causes chronic pain and stress, leads to disorders of physiological and reproductive processes, since stress has direct negative impact on numerous cellular functions. A total of 66 dairy cows, 50 Holstein-Friesian cows kept on PD Butmir and 16 Simmental cows kept on a private mini farm, were included in the study. At PD Butmir, cows were kept in tie-stall housing system, while on a mini-farm they were kept free. Hormonal protocols of estrus and ovulation synchronization were used in April, May and June 2019. Cows were subjected to two estrus synchronization and ovulation protocols, Ovsynch and Cosynch72. At PD Butmir, 25 cows were subjected to Ovsynch and Cosynch72 protocols, respectively. At the mini-farm only Ovsynch protocol was applied. The Ovsynch protocol applied on PD Butmir had success in conception rate of 12% (n = 3), while the Cosynch72 protocol gave a score of 36% (n = 9). On the mini-farm, Ovsynch resulted in a conception of 25% (n = 4). Based on our results, the Cosynch72 protocol, compared to the Ovsynch protocol, was a better choice in the case of Holstein-Friesian cows kept in the tie-stall housing system. In the Simmental cows kept in the free stall system, the Ovsynch protocol proved to be better choice in achieving conception, compared to the Holstein-Friesian cows. Therefore, it is necessary to test several different protocols of estrus and ovulation synchronization, in order to find the most optimal one for a certain breed, type of keeping and breeding.

Parkinson`s disease (PD) is a progressive neurodegenerative disorder involving dopaminergic neurons from the substantia nigra. The loss of dopaminergic neurons results in decreased dopamine (DA) release in the striatum and thus impaired motor functions. DA is one of the key neurotransmitters monitored for the diagnosis, and during the progression and treatment of PD. Therefore, sensitive and selective DA detection methods are of high clinical relevance. In this study, a new microfluidic device utilized for electrochemical DA detection is reported. The microfluidic sensing device operates in the range of 0.1 - 1000 nM DA requiring only ~ 2.4 µL sample volume, which corresponds to detectable 240 amol of DA. Using this sensor, we were able to monitor the changes in DA levels in cerebrospinal fluid (CSF) and plasma of a mouse model of PD and following the treatment of drug L-3,4-dihydroxyphenylalanine (L-DOPA), which reversed the parkinsonian symptoms in PD mice.

Abnormal dopamine neurotransmission is associated with several neurological and psychiatric disorders such as Parkinson's disease, schizophrenia, attention deficiency and hyperactivity disorder and addiction. Developing highly sensitive, selective and fast dopamine monitoring methods is of high importance especially for the early diagnosis of these diseases. Herein, we report a new ultrasensitive electrochemical sensing platform for in situ monitoring of cell-secreted dopamine using Au-coated arrays of micropyramid structures integrated directly into a Petri dish. This approach enables the monitoring of dopamine released from cells in real-time without need for relocating cultured cells. According to the electrochemical analyses, our dopamine sensing platform exhibits excellent analytical characteristics with a detection limit of 0.5 nM, a wide linear range of 0.01 to 500 µM, and a sensitivity of 0.18 µA/µM. The sensor also has remarkable selectivity towards DA in the presence of different potentially interfering small molecules. The developed electrochemical sensor has a great potential for in vitro analysis of neuronal cells as well as early diagnosis of different neurological diseases related to abnormal levels of dopamine.

Nanotechnology's rapid development of nanostructured materials with disruptive material properties has inspired research for their use as electrocatalysts to potentially substitute enzymes. Herein, a novel electrocatalytic nanomaterial was constructed by growing gold nanograss (AuNG) on 2D nanoassemblies of gold nanocubes (AuNC). The resulting structure (NG@NC) was used for the detection of H2O2via its electrochemical reduction. The NG@NC electrode displayed a large active surface area, resulting in improved electron transfer efficiency. On the nanoscale, AuNG maintained its structure, providing high stability and reproducibility of the sensing platform. Our nanostructured electrode showed excellent catalytic activity towards H2O2 at an applied potential of -0.5 V vs Ag/AgCl. This facilitated H2O2 detection with excellent selectivity in an environment like human urine, and a linear response from 50 µM to 30 mM, with a sensitivity of 100.66 ± 4.0 μA mM-1 cm-2. The NG@NC-based sensor hence shows great potential in nonenzymatic electrochemical sensing.

Abstract The skin, as the largest and most accessible organ in the human body, contains biofluids rich in biomarkers useful not only in diagnosis and monitoring of diseases, but also in profiling an individual’s wellbeing. Advancements in micro- and nanotechnology research have underpinned the development of multifunctional wearable sensing devices. Those sensors may allow monitoring of physiological parameters from different skin sections such as epidermis, dermis and hypodermis by sampling various bodily fluids. Our review summarizes current advances in wearable biosensors for on-skin analysis of sweat, transdermal monitoring of interstitial fluid and analysis of subcutaneous fluids via implanted devices. The review is divided into three main parts describing biosensors acting on the different skin sections. Each part focuses on recent scientific and technological advancements in the wearable biosensing field by highlighting critical challenges as well as providing information on how these barriers are being addressed by the research community.

Nowadays, there is increasing number of electrochemical biosensors which utilize chitosan (Ch); as an enzyme immobilization matrix, and conductive nanomaterials; as electron carriers improving sensitivity of the biosensor. However, the challenge these sensors face is the lack of uniform dispersion of nanomaterials throughout the Ch film, which can negatively affect analytical performance of the biosensor. In this study, we report the development of an enzyme immobilization matrix that displays enhanced electrochemical performance thanks to a novel conductive thin film prepared via in situ electrocopolymerization of pyrrole (Py) and thiophene-grafted chitosan (Th-Ch). This is a simple thin film preparation method that can help overcome aforementioned challenges by providing a uniformly distributed conductive layer on the electrode. We are also for the first time reporting the synthesis and characterization of Th-Ch, where grafted Th plays an essential role as a linking group between Ch and Py. The resulting conductive Ch-based thin film was modified with glucose oxidase (GOx) which served as a model enzyme. In situ electrocopolymerization of Py with Th-Ch resulted in a highly conductive thin film enabling approximately 40% higher sensitivity when compared to a Py-Ch composite. This new type of composite thin film is promising in biosensor technology due to its biocompatibility, the chemically and physically modifiable structure, as well as its electrical conductivity.