With zoonotic outbreaks on the rise, rapid and accurate infectious disease diagnostics are critical for both human and animal health. Traditional lateral flow assays lack sensitivity and specificity, while isothermal amplification methods like LAMP, though rapid, can be hindered by optical detection issues. We present an electrochemical nucleic acid amplification test (NAAT) that combines isothermal amplification with real-time voltammetric detection. This novel method relies on monitoring of amplification-associated proton release through redox probing of a pH-sensing compound. The method shows high concordance with RT-qPCR under the tested conditions and demonstrates a limit of detection (LOD) of 50 copies/reaction for IAV. In RNA purified from clinical samples, 231/234 (98.7%) are concordant with RT-qPCR for SARS-CoV-2, IAV, IBV, or RSV A. In a proof-of-concept extraction-free workflow, 14/14 equine nasal swab samples are correctly classified for EHV-5 relative to qPCR. Together, these data support the feasibility of real-time voltammetric LAMP across several sample types, while broader point-of-care validation across additional matrices and prospective cohorts remains to be established.

The integration of biological tissues with conducting polymers is crucial for the advancement of bioelectronics. Although the potential toxicity of some conducting-ink components is an acknowledged constraint for in vivo use, a more fundamental limitation is the lack of molecular understanding of how conducting polymers interact with biological barriers. This study addresses some of the limitations by presenting a novel method for direct polymerization of pyrrole on excised skin in vitro and investigates the evolving skin/conducting polymer interface using electrical impedance spectroscopy (EIS), X-ray diffraction, vapor sorption, and complementary analyses. Direct polymerization of pyrrole on skin is performed by applying an aqueous pyrrole solution to the dermal side and an oxidant (ferric ion solution) on the stratum corneum (SC) side of the skin membrane fixed in a Franz cell. EIS measurements show a marked reduction in skin barrier resistance after PPy formation, whereas control experiments produced the opposite trend, confirming that the resistance drop arises specifically from polymerization. Our complementary analyses indicate that polymerization is primarily localized at the solution-SC interface but also support the formation of an electrically coupled pathway across the barrier. These results provide molecular-level insight into polymer-SC interactions, imply the formation of a coherent conductive junction that extends through the SC layers, and inform the design of future skin-integrated bioelectronic materials.

Aim: Understanding the interactions between extracellular matrix (ECM) proteins and proteases is essential for elucidating the mechanisms of ECM remodeling in both health and disease. The integration of real-time, label-free, and surface-sensitive techniques based on distinct physical principles enables detailed characterization of protease activity at the ECM substrate-liquid interface. Based on these kinds of techniques, this study focuses on investigating the dynamic interactions between protein adlayers and proteases, offering new insights into complex ECM remodeling processes. Experiments: The adsorption behavior and resulting adlayer properties of collagen and elastin, used as ECM model substrates, and the proteolytic activity of collagenase and elastase, were studied using synchronized quartz crystal microbalance with dissipation monitoring (QCM-D) and localized surface plasmon resonance (LSPR). Changes in adsorbed mass, viscoelastic properties, and near-surface dielectric environment were monitored via shifts in frequency (Δf), energy dissipation (ΔD), and plasmon resonance peak (∆λ), respectively. Atomic force microscopy (AFM) was employed to validate film morphology and mechanical alterations before and after proteolytic digestion. Findings: While the QCM-D/LSPR signals both detect mass uptake during protein adsorption and mass loss during proteolysis, synchronized measurements, complemented with AFM imaging, reveal more complex responses arising from the differing surface sensitivities of the techniques. Our integrated analysis show substantial differences in adlayer morphology and proteolytic degradation. Collagen forms a vertically heterogeneous adlayer with a dense near-surface layer and a highly viscoelastic outer layer of protruding fibrils (Δf ≈ −100 to −240 Hz, ΔD ≈ 40–70 ppm, and ∆λ ≈ 0.7 nm), whereas elastin adsorbs as a thinner, more rigid film (Δf ≈ −36 to −40 Hz, ΔD ≈ 2–3 ppm, and ∆λ ≈ 0.4 nm). Real-time monitoring reveals that collagenase primarily degrades the protruding collagen fibrils, significantly affecting all QCM-D and LSPR signals—particularly showing a clear overtone dependence in ΔD and Δf shifts—while elastase digestion of elastin occurs without overtone dependence and results in more pronounced changes in Δf and ∆λ, with comparatively low effect on ΔD. Cross-reactivity experiments confirm substrate specificity; however, both proteases show non-specific activity. Inhibition studies demonstrate that QCM-D can detect both true enzymatic inactivity and substrate-inhibitor interactions that mimic inhibition in conventional assays, for example by physically adsorbing to the substrate and thereby shielding it from proteolysis.

Skin cancer is one of the most common types of cancer worldwide, with exposure to UVB radiation being a significant risk factor for its development. To prevent skin cancer, continuous research efforts have focused on finding suitable photoprotective ingredients from natural sources that are also environmentally friendly. This study aimed to develop oil-in-water photoprotective nanoemulsions containing marine macroalgae extract. A Box-Behnken experimental design was used to identify the most promising formulation composition, resulting in optimal physical properties. These properties, including droplet size, polydispersity index (PDI), and zeta potential, were evaluated using dynamic light scattering (DLS). To assess the photoprotection capacity of the formulations, electrical impedance spectroscopy (EIS) was employed to evaluate alterations in the electrical characteristics of excised pig skin membranes placed in Franz cells equipped with a 4-electrode set-up. The final composition of the nanoemulsion was caprylic/capric triglycerides 4%, Macrogolglycerol ricinoleate 30%, and algae extract 1%. The nanoemulsions had an average droplet size of 128.5 +/- 8.6 nm, a PDI of 0.25 +/- 0.06, and a zeta potential of 45.14 +/- 0.02 mV. Compared to the control group, the photoprotective capacity of the oil-in-water nanoemulsions was statistically significant. Specifically, only a 15% reduction in the skin membrane electrical resistance following UVB exposure was observed when the formulation containing algae extract was used, whereas a 50% reduction was observed for the vehicle. In conclusion, this work demonstrates that the developed nanoemulsions based on natural ingredients show promising protective capacity against UVB exposure of the skin.

BACKGROUND: Staphylococcus aureus and Staphylococcus epidermidis normally coexist on the skin of healthy individuals. Their ratio and pathogenicity, however, change with different skin diseases and thus, the ability to control bacterial growth on the skin is important. Propylene glycol (PG), a widely used component in topical formulations, has been proved to have antimicrobial activity.

OBJECTIVES: To investigate the concentration-dependent antimicrobial properties of PG against S. aureus and S. epidermidis skin isolates in mono- and co-culture at neutral (pH 7.4) and mildly acidic (pH 5) conditions.

RESULTS AND DISCUSSION: The minimum inhibitory concentration of PG was 12.5% at both pH 5 and pH 7.4 for the selected bacterial strains. The viability of S. aureus exposed to 12.5% PG was lower at pH 5 than at pH 7.4, and post-treatment regrowth of S. aureus occurred slowly at acidic pH. When both bacterial strains were incubated in media containing 12.5% PG at pH 5 for 48 hours, S. epidermidis retained significantly higher viability, while at pH 7.4, the results were opposite.

CONCLUSIONS: Under the acidic conditions of healthy skin, pathogenic S. aureus is more suppressed by 12.5% PG than commensal S. epidermidis.

The application of functional nanomaterials (FNMs) in sensing and analytical chemistry has opened a new era of conceptual design for next-generation tracing tools. They have proven their worth through high stability, biocompatibility along with rapid response towards recognition events even at ultra-weak biological signals. This has promoted the field of life science and biomedicine in terms of therapeutics and theranostics. However, studies performed to discover the use of FNMs in wearable sensors are limited. As the market for wearable sensors expands, there is a continuous demand for flexible chips to be integrated with skin or clothes. The FNMs, such as silicon nanolayer or carbon-based nanomaterials in this direction possess lower flexural rigidity than bulk counterparts to demonstrate multi-functionality. This perspective review targets the significant advances of FNMs in wearable sensors. Here, we discuss state-of-the-art FNM based wearable chips. With the initial introduction of FNMs and their unique properties, we elaborate their importance in an integrated system of wearable sensors. The detailed discussion along with suitable examples is also presented in the second section of the review and at last, we explain the need for more extensive research on FNMs to further their applications in the wearable sensing industry.

Purpose: To evade immunosurveillance many cancers convert tryptophan (Trp) into kynurenine (Kyn), which induces immunotolerance and suppresses immune responses. Elevated Kyn amounts have been found in blood from patients with cutaneous melanoma. This study aimed to investigate whether higher Kyn abundance and lower Trp abundance can be detected on the surface of cutaneous melanoma lesions compared with adjacent non-lesional skin.

Methods: Sixteen patients with suspected melanomas were enrolled in this study. All lesions were excised and histopathologically diagnosed: 7 lesions were diagnosed as invasive malignant melanomas (MM), 6 as melanomas in situ (MIS), and 3 as benign lesions (BL). Non-invasive metabolite sampling was performed by tape stripping of suspected skin lesions and adjacent healthy non-lesional (NL) skin. Trp, Kyn, tyrosine (Tyr), and phenylalanine (Phe) were quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Electrical impedance spectroscopy (EIS) measurements were conducted to assess skin barrier integrity.

Results: Levels of all metabolites, Tyr (x6), Phe (x6), Trp (x5), and Kyn (x3), were significantly higher in MM lesions compared with adjacent NL skin, resulting in an elevated Trp/Kyn ratio. Trp levels increased less than Phe and Tyr levels, suggesting a potential increase in Trp depletion. Skin resistance in MM lesions was half that of NL skin. No differences were observed between MIS or BL and NL skin.

Conclusions: Non-invasive skin sampling revealed elevated Tyr, Phe, Trp and Kyn levels in MM skin, which is likely the result of compromised skin barrier at this stage of cutaneous melanoma.

This study presents a comprehensive exploration of the electrochemical behavior of layer-by-layer assemblies comprising silver nanoparticles (AgNPs), poly-l-lysine (PLL), and bovine serum albumin (BSA) on gold surfaces. AgNPs were synthesized using the reduction of silver ions with the synergy of ascorbic acid and citrate in the presence of sodium chloride. The obtained silver nanoparticles were characterized using transmission electron microscopy, dynamic light scattering and UV-Vis spectroscopy. A typical preparation produced AgNPs with a plasmon peak at 402 nm, a diameter of 27.5 nm and zeta potential of -37 mV. Employing a drop-coating approach, we successfully achieved stable multilayers of AgNPs, PLL, and BSA. Cyclic voltammetry revealed well-defined, bell-shaped oxidation and reduction peaks of AgNPs within the multilayers, demonstrating complete conversion to AgCl and back to Ag. Notably, the stripping of AgNPs on a monolayer of PLL prepared at pH 4.00 resulted in the highest current intensity, contrasting with lower intensities observed for PLL monolayers prepared at pH 7.01 and pH 9.01. Despite the absence of a splitting reduction peak in the presence of biopolymer materials, a noteworthy observation emerged: the peak splitting exclusively occurred when PLL/AgNP layers, terminated with PLL, were exposed to BSA in the solution. image

Since the progression of biofilm formation is related to the success of infection treatment, detecting microbial biofilms is of great interest. Biofilms of Gram-positive Staphylococcus aureus and Streptococcus gordonii bacteria, Gram-negative Pseudomonas aeruginosa and Escherichia coli bacteria, and Candida albicans yeast were examined using potentiometric, amperometric, and wireless readout modes in this study. As a biofilm formed, the open circuit potential (OCP) of biofilm hosting electrode (bioanode) became increasingly negative. Depending on the microorganism, the OCP ranged from −70 to −250 mV. The co-culture generated the most negative OCP (−300 mV vs Ag/AgCl), while the single-species biofilm formed by E. coli developed the least negative (−70 mV). The OCP of a fungal biofilm formed by C. albicans was −100 mV. The difference in electrode currents generated by biofilms was more pronounced. The current density of the S. aureus biofilm was 0.9‧10−7 A cm−2, while the value of the P. aeruginosa biofilm was 1.3‧10−6 A cm−2. Importantly, a biofilm formed by a co-culture of S. aureus and P. aeruginosa had a slightly higher negative OCP value and current density than the most electrogenic P. aeruginosa single-species biofilm. We present evidence that bacteria can share redox mediators found in multi-species biofilms. This synergy, enabling higher current and OCP values of multi-species biofilm hosting electrodes, could be beneficial for electrochemical detection of infectious biofilms in clinics. We demonstrate that the electrogenic biofilm can provide basis to construct novel wireless, chip-free, and battery-free biofilm detection method.

Amorphous Ti–O thin films were synthesized by reactive magnetron sputtering and their affinity to H2O2 was studied electrochemically. They exhibit a pronounced affinity to H2O2, with TiO0.6 outperforming TiO1.5 and TiO2. Cathodic currents in the range of −211 μA/cm2 suggest that TiO0.6 is highly electroactive to H2O2. Molecular dynamics simulations based on density functional theory revealed rapid dissociation of H2O2 into OH on Ti–O surfaces, leading to diffusion of OH, facilitating both oxidation and reduction processes. These OH groups predominantly dock onto bridge and atop sites, oxidizing the surfaces. Notably, stronger interactions observed for lower oxidation states give rise to higher cathodic currents. Additionally, the ability of amorphous Ti–O thin films to generate free H atoms implies a possible reduction mechanism, likely leading to the desorption of H2O. Hence, amorphous TiO0.6 is more suitable for detection and monitoring of H2O2 than higher oxidation states in their crystalline forms, e.g., rutile TiO2, known as a benchmark for such applications.