Pressure ulcers (PUs), commonly referred to as bedsores, are a major health problem for which early detection remains challenging. Volatile organic compounds (VOCs) released from pressure-affected skin have been proposed as potential biomarkers, providing a complementary approach to conventional visual and pressure-based monitoring. In this study, a cross-reactive electronic nose (e-nose) comprising nine quantum resistive vapour sensors (vQRSs) was evaluated for the detection of three VOCs previously associated with pressure-ulcer-related skin emissions: benzyl alcohol, pentadecane and 1-tetradecene. The vQRS transducers consisted of carbon nanotube (CNT) networks functionalized with different polymer matrices, namely poly (vinylpyrrolidone), poly (vinyl acetate), poly (lactic acid), poly (ethylene glycol), poly (caprolactone), poly (methyl methacrylate), poly (styrene-co-acrylonitrile), polystyrene and sulfonated poly (ether ether ketone). The individual sensors were first evaluated using benzyl alcohol and water vapour at concentrations ranging from approximately 100 ppb to 1 ppm. A measurable response was obtained at 100 ppb, with signal-to-noise ratios exceeding five for six vQRSs. Water vapour modified the response amplitude and apparent sensitivity to benzyl alcohol, highlighting the importance of humidity effects under skin-relevant conditions. The sensor array was subsequently exposed to synthetic mixtures containing the selected biomarkers in a complex VOC background with controlled water vapour content. Principal component analysis (PCA) of the sensor responses enabled discrimination between the different biomarker-containing mixtures, their concentrations, and the background mixture. Combining the maximum response amplitude with the integrated response area further improved separation in the PCA score space compared with amplitude alone. PCA was used as an exploratory visualization tool; no supervised classification or cross-validation was performed, and the data were obtained from synthetic mixtures and a single background donor. These results demonstrate the feasibility of using a cross-reactive CNT/polymer vQRS array to detect pressure-ulcer-associated VOC signatures under controlled laboratory conditions. The study illustrates the possible recognition of synthetic blends of three candidate VOCs added to a healthy-skin background (one donor, four skin sites). Further studies using real skin emissions from individuals will target the discrimination between healthy and patients with pressure ulcers to assess the robustness and clinical diagnostic value of the approach.
We show here the utility of gold nanoparticles (AuNPs) functionalized with PEG, terminated with neutral, zwitterionic, or charged chemical groups as a versatile and homogenous platform to investigate NP–host interactions. We screened nanocoat recognition by FXII using human plasma clotting as an easy and rapid readout parameter. Distinctive procoagulant–anticoagulant patterns were found, depending not only on coat overall charge, but also on the chemical nature of charged groups and on their spatial organization. The systematic comparison of chemically fine-tuned NP coats provides a powerful tool, offering relevant insights for the rational design of nanomaterials with predictable biological behavior.
Acidity, hypoxia, redox imbalance, and altered enzyme activity in the tumor microenvironment (TME) can be used to regulate nanocarrier structure and drug release. However, these conditions vary among tumors and across regions within individual tumors and overlap with certain normal physiological and inflammatory processes. This review examines TME-responsive nanomedicines for chemotherapy, phototherapy, immunomodulation, and theranostics in terms of their triggering conditions, response mechanisms, and carrier materials. Particular attention is given to matching activation thresholds to biological compartments, the relationship between delivery and release, and the biological interpretation of imaging signals. By comparing representative original studies, we examine the benefits of multiresponsive designs, potential off-target activation, and manufacturing complexity, while distinguishing the clinical use of conventional nanoformulations from clinical validation of TME-responsive mechanisms. Current studies demonstrate the feasibility of conditional drug release and local microenvironment modulation, but their clinical value remains to be established through consistent product quality, evidence of in vivo activation, and comparative efficacy studies.
Hydrogel-forming microneedles (HFMNs) are minimally invasive interfaces that access interstitial fluid (ISF) through skin penetration, swelling-mediated uptake, analyte diffusion, and hydrated sensor integration. This review examines HFMN architectures, skin–device interfaces, ISF transport, molecular-recognition and signal-transduction strategies, analytical performance, benchmarking, wear-associated failure modes, therapeutic monitoring, and translational priorities. The field has expanded from glucose sensing to metabolites, ions, hormones, proteins, nucleic acids, microbial and wound biomarkers, and therapeutic drugs, enabled by advances in hydrogel chemistry, conductive networks, nanostructured electrodes, catalysis, affinity recognition, molecular imprinting, optical readouts, and multiplexed wearables. Performance remains context dependent and requires physiological range, calibration stability, biofouling resistance, reliable insertion, validated ISF-reference correlations, and interpretable thresholds. Evidence is strongest in artificial matrices, ex vivo tissue, and animals, while human validation remains limited. Translation will require standardized mechanics and transport reporting, longer wear studies, sterilization-compatible chemistries, scalable manufacturing, and clinical validation. HFMNs may complement rather than replace blood-based diagnostics.
Asthma is a prevalent, long-term inflammatory airway condition that is difficult to diagnose and treat because there is no single reliable diagnostic test. Misdiagnosis is therefore common, with rates as high as 73% in juvenile groups and up to 35% in adult populations. This ultimately exacerbates their illness by postponing therapy for some people and administering needless medication to others. Although well-known biomarkers such as blood eosinophils and fractional exhaled nitric oxide, as well as conventional diagnostic techniques such as spirometry, have improved clinical assessment, they are nevertheless constrained in many healthcare settings by limited availability, high cost, and inconsistent use. Furthermore, these indicators primarily reflect type-2 inflammation and are less useful for non-type-2 asthma, highlighting the need for more comprehensive, readily accessible diagnostic techniques. Identifying novel biomarkers of oxidative stress, metabolic alterations, and airway inflammation, including volatile organic compounds and redox-related chemicals, has been the focus of recent studies. These biomarkers offer opportunities for improved disease phenotyping and non-invasive detection. Simultaneously, advances in biosensor technology have enabled highly sensitive platforms to rapidly detect these biomarkers at low concentrations. In particular, optical biosensors are becoming more and more popular due to their ability to do real-time detection without the need for labels and their ease of miniaturization for point-of-care devices. This work summarizes traditional diagnostic tools alongside existing information on asthma phenotypes and clinically important biomarkers, and discusses advanced biosensors ranging from electrochemical to optical systems, including recent developments in nanomaterial-enhanced optical biosensing techniques. The importance of artificial intelligence and smartphone-integrated hardware is also covered, along with the main challenges that need to be overcome for these technologies to become useful clinical tools for asthma diagnosis and monitoring.
