Rapid detection of antibiotic-resistant bacteria is a crucial tool in the global fight against antimicrobial resistance, helping to limit the spread of resistance and guide treatment decisions. Here, we report the design, synthesis, and electrochemical evaluation of β-lactam-based redox-activatable probes for detecting β-lactamase activity. The probes incorporate a β-lactam core linked to redox reporters through cleavable linkages, enabling signal generation upon enzymatic hydrolysis. High-performance liquid chromatography and differential pulse voltammetry analyses were used to assess time-dependent activation and concentration-dependent responses against commercial β-lactamase blends and metallo-β-lactamases. Selected probes, bearing cephalosporin recognition motifs and maltol redox reporters, were further evaluated against clinical isolates, demonstrating selective activation in carbapenemase-producing strains. To extend the platform toward solid-state biosensing, an azide-functionalized analog was clicked on alkyne-modified glassy carbon electrodes. Stepwise surface functionalization and immobilization were validated electrochemically using model redox reporters, confirming their activity. The immobilized probe retained responsiveness, demonstrating the feasibility of integrating this sensing strategy into solid-state diagnostic devices. By integrating stable cephalosporin scaffolds with redox-reporter signaling, this work introduces a novel probe system that unites chemical probe design with surface-based electrochemical sensing, providing a strong foundation for the development of portable, point-of-care diagnostics for β-lactamase-mediated antibiotic resistance.

Food, especially fish meat, is extremely vulnerable to oxidation and microbiological deterioration. Therefore, effective analytical techniques for quality control and safety monitoring are required. Electrochemical biosensors have become reliable, rapid, and affordable devices for in-field and real-time food quality assessment. However, their application is often limited in point-of-need scenarios due to the requirement for intensive sample preparation. Here, we introduce a microneedle array (MNA)-based electrochemical biosensor, designed for direct food safety and quality analysis without the need for sample preparation. A gold (Au)-coated polymeric MNA was functionalized with a chitosan-gold nanoparticles (Ch-AuNP) nanocomposite and further modified by immobilizing xanthine oxidase (XO) for selective hypoxanthine (HX) detection. The MNA-based biosensor exhibited a linear range between 5 and 50 μM, and 50 to 200 μM, with a sensitivity of 0.024 μA/μM and a limit of detection (LOD) of 2.18 ± 0.75 μM for HX, with a response time of approximately 100 s. Furthermore, the MNA-based biosensor was successfully utilized for monitoring HX levels in fish tissue samples over 48 h, showing strong agreement with results obtained from a commercial Amplex Red assay kit. The technology can be used for real-time food quality assessment and food safety monitoring due to its high sensitivity, interference tolerance, and lack of requirement for sample preparation.

BACKGROUND Lower respiratory infections (LRIs) remain the world's leading infectious cause of death. This analysis from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2023 provides global, regional, and national estimates of LRI incidence, mortality, and disability-adjusted life-years (DALYs), with attribution to 26 pathogens, including 11 newly modelled pathogens, across 204 countries and territories from 1990 to 2023. With new data and revised modelling techniques, these estimates serve as an update and expansion to GBD 2021. Through these estimates, we also aimed to assess progress towards the 2025 Global Action Plan for the Prevention and Control of Pneumonia and Diarrhoea (GAPPD) target for pneumonia mortality in children younger than 5 years. METHODS Mortality from LRIs, defined as physician-diagnosed pneumonia or bronchiolitis, was estimated using the Cause of Death Ensemble model with data from vital registration, verbal autopsy, surveillance, and minimally invasive tissue sampling. The Bayesian meta-regression tool DisMod-MR 2.1 was used to model overall morbidity due to LRIs. DALYs were calculated as the sum of years of life lost (YLLs) and years lived with disability (YLDs) for all locations, years, age groups, and sexes. We modelled pathogen-specific case-fatality ratios (CFRs) for each age group and location using splined binomial regression to create internally consistent estimates of incidence and mortality proportions attributable to viral, fungal, parasitic, and bacterial pathogens. Progress was assessed towards the GAPPD target of less than three deaths from pneumonia per 1000 livebirths, which is roughly equivalent to a mortality rate of less than 60 deaths per 100 000 children younger than 5 years. FINDINGS In 2023, LRIs were responsible for 2·50 million (95% uncertainty interval [UI] 2·24-2·81) deaths and 98·7 million (87·7-112) DALYs, with children younger than 5 years and adults aged 70 years and older carrying the highest burden. LRI mortality in children younger than 5 years fell by 33·4% (10·4-47·4) since 2010, with a global mortality rate of 94·8 (75·6-116·4) per 100 000 person-years in 2023. Among adults aged 70 years and older, the burden remained substantial with only marginal declines since 2010. A mortality rate of less than 60 deaths per 100 000 for children younger than 5 years was met by 129 of the 204 modelled countries in 2023. At a super-regional level, sub-Saharan Africa had an aggregate mortality rate in children younger than 5 years (hereafter referred to as under-5 mortality rate) furthest from the GAPPD target. Streptococcus pneumoniae continued to account for the largest number of LRI deaths globally (634 000 [95% UI 565 000-721 000] deaths or 25·3% [24·5-26·1] of all LRI deaths), followed by Staphylococcus aureus (271 000 [243 000-298 000] deaths or 10·9% [10·3-11·3]), and Klebsiella pneumoniae (228 000 [204 000-261 000] deaths or 9·1% [8·8-9·5]). Among pathogens newly modelled in this study, non-tuberculous mycobacteria (responsible for 177 000 [95% UI 155 000-201 000] deaths) and Aspergillus spp (responsible for 67 800 [59 900-75 900] deaths) emerged as important contributors. Altogether, the 11 newly modelled pathogens accounted for approximately 22% of LRI deaths. INTERPRETATION This comprehensive analysis underscores both the gains achieved through vaccination and the challenges that remain in controlling the LRI burden globally. Furthermore, it demonstrates persistent disparities in disease burden, with the highest mortality rates concentrated in countries in sub-Saharan Africa. Globally, as well as in these high-burden locations, the under-5 LRI mortality rate remains well above the GAPPD target. Progress towards this target requires equitable access to vaccines and preventive therapies-including newer interventions such as respiratory syncytial virus monoclonal antibodies-and health systems capable of early diagnosis and treatment. Expanding surveillance of emerging pathogens, strengthening adult immunisation programmes, and combating vaccine hesitancy are also crucial. As the global population ages, the dual challenge of sustaining gains in child survival while addressing the rising vulnerability in older adults will shape future pneumonia control strategies. FUNDING Gates Foundation.

Wearable electrochemical biosensors offer a promising alternative to conventional invasive blood‐based methods for monitoring biomarkers in diagnostic or therapeutic applications. Microneedle (MN)‐based technology provides direct access to the skin's interstitial fluid (ISF), enabling real‐time monitoring of biomarkers. Nevertheless, current micro‐ and nanofabrication techniques do not adequately support the development of MN‐based wearable technology that can utilize soft hybrid conductive inks, limiting its use in transdermal biosensing. Herein, an MN‐based biosensing platform is developed by integrating 3D printing, soft lithography, and hybrid conductive ink technology, featuring a fenestrated MN shell (FMNS) that serves as a protective layer for the inner hybrid conductive ink coating and prevents delamination during skin application. This FMNS patch demonstrates a wide pH monitoring range, high selectivity and accurate detection of subtle ISF pH changes, safe integration of hybrid conductive inks, and reduced fabrication time and cost when compared to other microfabrication methods such as lithography and deep reactive ion etching. The biosensor excels in protecting the biosensing layer and demonstrates excellent analytical performance in monitoring changes in pH levels of the skin ISF. This micro‐ and nanofabrication approach has great potential in integrating hybrid conductive ink technology into transdermal wearable devices for health monitoring and diagnostics.

Mammalian cells, particularly human cell culture models, are essential for studying disease pathophysiology and producing cell-based therapeutic products. Monitoring and controlling cell culture conditions accurately is essential for optimal cell growth and health, as even minor variations can significantly influence cell behavior. The presence of viruses, bacteria, and their by-products are key indicators of cell culture contamination. Conventional assays for quantifying cellular health and microbial contaminants such as endotoxins are end-point assays that are often laborious, require specialized equipment, and typically detect contamination only at advanced stages. For example, the chromogenic Limulus amoebocyte lysate assay, used for quantifying endotoxin, a bacte rial by-product, is often susceptible to interference from serum proteins in the culture medium. In this work, we present a simple and sensitive aptamer-based biosensor designed to detect bacterial-secreted endotoxins in various complex cell culture media. As a proof of concept, human induced pluripotent stem cells (hiPSCs) were deliberately contaminated with Escherichia coli (E. coli), and the biosensor's response to endotoxins released by the bacteria was monitored over a 24-h period. The biosensor demonstrated a reliable linear response with a detection limit of 0.33 ± 0.06 pg/mL in DMEM and 0.142 ± 0.025 pg/mL in StemFlex medium. Its performance in complex sample matrices suggests the potential for integration with industrial-scale cell culture systems for real-time contamination detection, providing a cost-effective, efficient, and timely method to monitor cell health and ensure sterile conditions for therapeutic cell cultivation.

Glucose levels serve as a fundamental indicator of cell health, reflecting crucial aspects of cellular metabolism and energy production. While effective, traditional methods such as spectrophotometry and chromatography have limitations, such as labour-intensive sample collection, reliance on bulky equipment, extensive sample preparation, and prolonged experimental durations. To address these issues, we introduce a micropillar-based microfluidic electrochemical device (MED) for real-time monitoring of glucose levels in diverse cell culture systems, including human induced pluripotent stem cells (hiPSCs) and murine fibroblast cells (GP + E86). This biosensor demonstrates a linear range of 0.025-1.50 mM and a high sensitivity of 4.71 ± 0.13 μA. mM-1, and a low limit of detection of 19.10 ± 0.50 μM. The MED not only delivered fast glucose measurements with accuracy and reliability comparable to ultra-high-performance liquid chromatography (UHPLC) but was also specifically evaluated on GP + E86 murine fibroblast cells at varying seeding densities (1:5 and 1:10 ratios), across different culturing times to accurately monitor dynamic metabolic shifts associated with various growth phases. Furthermore, the MED effectively detected significant changes in glucose consumption in hiPSCs cell cultures contaminated with Escherichia coli (E. coli), highlighting its potential for early contamination detection. Integrating non-invasive, continuous monitoring platforms enhances the reliability of experimental outcomes by enabling cell health monitoring without disrupting the cell culture process. This approach enables real-time monitoring of cell cultures ensuring accurate detection of metabolic changes and early detection of media contamination.

Microneedles (MNs) are emerging as versatile tools for both therapeutic drug delivery and diagnostic monitoring. Unlike hypodermic needles, MNs achieve these applications with minimal or no pain and customizable designs, making them suitable for personalized medicine. Understanding the key design parameters and the challenges during contact with biofluids is crucial to optimizing their use across applications. This review summarizes the current fabrication techniques and design considerations tailored to meet the distinct requirements for drug delivery and biosensing applications. We further underscore the current state of theranostic MNs that integrate drug delivery and biosensing and propose future directions for advancing MNs toward clinical use.

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.