The association of vasomotor symptoms with fracture risk and bone mineral density in postmenopausal women: a systematic review and meta-analysis of observational studies.

BACKGROUND/AIMS: Vasomotor symptoms (VMS) adversely affect postmenopausal quality of life. However, their association with bone health has not been elucidated. This study aimed to systematically review and meta-analyze the evidence regarding the association of VMS with fracture risk and bone mineral density (BMD) in peri- and postmenopausal women. METHODS: A literature search was conducted in PubMed, Scopus and Cochrane databases until 31 August 2023. Fracture, low BMD (osteoporosis/osteopenia) and mean change in lumbar spine (LS) and femoral neck (FN) BMD were assessed. The results are presented as odds ratio (OR) and mean difference (MD), respectively, with a 95% confidence interval (95% CI). The I2 index quantified heterogeneity. RESULTS: Twenty studies were included in the qualitative and 12 in the quantitative analysis (n=49,659). No difference in fractures between women with and without VMS was found (n=5, OR 1.04, 95% CI 0.93-1.16, I2 16%). However, VMS were associated with low BMD (n=5, OR 1.54, 95% CI 1.42-1.67, I2 0%). This difference was evident for LS (MD -0.019 g/cm2, 95% CI -0.03 to -0.008, I2 85.2%), but not for FN BMD (MD -0.010 g/cm2, 95% CI -0.021 to 0.001, I2 78.2%). These results were independent of VMS severity, age and study design. When the analysis was confined to studies that excluded menopausal hormone therapy use, the association with BMD remained significant. CONCLUSIONS: The presence of VMS is associated with low BMD in postmenopausal women, although it does not seem to increase fracture risk.

One-Pot Synthesis of a Robust Crosslinker-Free Thermo-Reversible Conducting Hydrogel Electrode for Epidermal Electronics.

Traditional epidermal electrodes, typically made of silver/silver chloride (Ag/AgCl), have been widely used in various applications, including electrophysiological recordings and biosignal monitoring. However, they present limitations due to inherent material mismatches with the skin. This often results in high interface impedance, discomfort, and potential skin irritation, particularly during prolonged use or for individuals with sensitive skin. While various tissue-mimicking materials have been explored, their mechanical advantages often come at the expense of conductivity, resulting in low-quality recordings. We herein report the facile fabrication of conducting and stretchable hydrogels using a "one-pot" method. This approach involves the synthesis of a natural hydrogel, termed Golde, composed of abundant and eco-friendly components, including gelatin, chitosan, and glycerol. To enhance the conductivity of the hydrogel, various conducting materials, such as poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS), thermally reduced graphene (TRG), and MXene, are introduced. The resulting conducting hydrogels exhibit remarkable robustness, do not require crosslinkers, and possess a unique thermo-reversible property, simplifying the fabrication process and ensuring enhanced long-term stability. Moreover, their fabrication is sustainable, as it employs environmentally friendly materials and processes while retaining their skin-friendly characteristics. The resulting hydrogel electrodes were tested for electrocardiogram (ECG) signal acquisition and outperformed commercial electrodes even when implemented in an all-flexible electrode setup simply using copper tape, owing to their inherent adhesiveness.

Microelectrode Arrays Measure Blocking of Voltage-Gated Calcium Ion Channels on Supported Lipid Bilayers Derived from Primary Neurons.

Drug studies targeting neuronal ion channels are crucial to understand neuronal function and develop therapies for neurological diseases. The traditional method to study neuronal ion-channel activities heavily relies on the whole-cell patch clamp as the industry standard. However, this technique is both technically challenging and labour-intensive, while involving the complexity of keeping cells alive with low throughput. Therefore, the shortcomings are limiting the efficiency of ion-channel-related neuroscience research and drug testing. Here, this work reports a new system of integrating neuron membranes with organic microelectrode arrays (OMEAs) for ion-channel-related drug studies. This work demonstrates that the supported lipid bilayers (SLBs) derived from both neuron-like (neuroblastoma) cells and primary neurons are integrated with OMEAs for the first time. The increased expression of voltage-gated calcium (CaV) ion channels on differentiated SH-SY5Y SLBs  compared to non-differentiated ones is sensed electrically. Also, dose-response of the CaV ion-channel blocking effect on primary cortical neuronal SLBs from rats is monitored. The dose range causing ion channel blocking is comparable to literature. This system overcomes the major challenges from traditional methods (e.g., patch clamp) and showcases an easy-to-test, rapid, ultra-sensitive, cell-free, and high-throughput platform to monitor dose-dependent ion-channel blocking effects on native neuronal membranes.

Organic Electronic Platform for Real-Time Phenotypic Screening of Extracellular-Vesicle-Driven Breast Cancer Metastasis.

Tumor-derived extracellular vesicles (TEVs) induce the epithelial-to-mesenchymal transition (EMT) in nonmalignant cells to promote invasion and cancer metastasis, representing a novel therapeutic target in a field severely lacking in efficacious antimetastasis treatments. However, scalable technologies that allow continuous, multiparametric monitoring for identifying metastasis inhibitors are absent. Here, the development of a functional phenotypic screening platform based on organic electrochemical transistors (OECTs) for real-time, noninvasive monitoring of TEV-induced EMT and screening of antimetastatic drugs is reported. TEVs derived from the triple-negative breast cancer cell line MDA-MB-231 induce EMT in nonmalignant breast epithelial cells (MCF10A) over a nine-day period, recapitulating a model of invasive ductal carcinoma metastasis. Immunoblot analysis and immunofluorescence imaging confirm the EMT status of TEV-treated cells, while dual optical and electrical readouts of cell phenotype are obtained using OECTs. Further, heparin, a competitive inhibitor of cell surface receptors, is identified as an effective blocker of TEV-induced EMT. Together, these results demonstrate the utility of the platform for TEV-targeted drug discovery, allowing for facile modeling of the transient drug response using electrical measurements, and provide proof of concept that inhibitors of TEV function have potential as antimetastatic drug candidates.

The convergence of traditional and digital biomarkers through AI-assisted biosensing: A new era in translational diagnostics?

Advances in consumer electronics, alongside the fields of microfluidics and nanotechnology have brought to the fore low-cost wearable/portable smart devices. Although numerous smart devices that track digital biomarkers have been successfully translated from bench-to-bedside, only a few follow the same fate when it comes to track traditional biomarkers. Current practices still involve laboratory-based tests, followed by blood collection, conducted in a clinical setting as they require trained personnel and specialized equipment. In fact, real-time, passive/active and robust sensing of physiological and behavioural data from patients that can feed artificial intelligence (AI)-based models can significantly improve decision-making, diagnosis and treatment at the point-of-procedure, by circumventing conventional methods of sampling, and in person investigation by expert pathologists, who are scarce in developing countries. This review brings together conventional and digital biomarker sensing through portable and autonomous miniaturized devices. We first summarise the technological advances in each field vs the current clinical practices and we conclude by merging the two worlds of traditional and digital biomarkers through AI/ML technologies to improve patient diagnosis and treatment. The fundamental role, limitations and prospects of AI in realizing this potential and enhancing the existing technologies to facilitate the development and clinical translation of "point-of-care" (POC) diagnostics is finally showcased.

Bacterial Membrane Mimetics: From Biosensing to Disease Prevention and Treatment.

Plasma membrane mimetics can potentially play a vital role in drug discovery and immunotherapy owing to the versatility to assemble facilely cellular membranes on surfaces and/or nanoparticles, allowing for direct assessment of drug/membrane interactions. Recently, bacterial membranes (BMs) have found widespread applications in biomedical research as antibiotic resistance is on the rise, and bacteria-associated infections have become one of the major causes of death worldwide. Over the last decade, BM research has greatly benefited from parallel advancements in nanotechnology and bioelectronics, resulting in multifaceted systems for a variety of sensing and drug discovery applications. As such, BMs coated on electroactive surfaces are a particularly promising label-free platform to investigate interfacial phenomena, as well as interactions with drugs at the first point of contact: the bacterial membrane. Another common approach suggests the use of lipid-coated nanoparticles as a drug carrier system for therapies for infectious diseases and cancer. Herein, we discuss emerging platforms that make use of BMs for biosensing, bioimaging, drug delivery/discovery, and immunotherapy, focusing on bacterial infections and cancer. Further, we detail the synthesis and characteristics of BMs, followed by various models for utilizing them in biomedical applications. The key research areas required to augment the characteristics of bacterial membranes to facilitate wider applicability are also touched upon. Overall, this review provides an interdisciplinary approach to exploit the potential of BMs and current emerging technologies to generate novel solutions to unmet clinical needs.

Electronic plants: the future of agriculture and urban ecosystems?

Electroactive and functional materials can be integrated with plants to monitor and control their development or to harvest and store energy. Seminal work by Stavrinidou et al. demonstrated electrically conducting polymers that grow inside living plants and form circuitry, unleashing exciting applications in smart agriculture and modern urban ecosystems.

Nanoscale Features of Tunable Bacterial Outer Membrane Models Revealed by Correlative Microscopy.

The rise of antibiotic resistance is a growing worldwide human health issue, with major socioeconomic implications. An understanding of the interactions occurring at the bacterial membrane is crucial for the generation of new antibiotics. Supported lipid bilayers (SLBs) made from reconstituted lipid vesicles have been used to mimic these membranes, but their utility has been restricted by the simplistic nature of these systems. A breakthrough in the field has come with the use of outer membrane vesicles derived from Gram-negative bacteria to form SLBs, thus providing a more physiologically relevant system. These complex bilayer systems hold promise but have not yet been fully characterized in terms of their composition, ratio of natural to synthetic components, and membrane protein content. Here, we use correlative atomic force microscopy (AFM) with structured illumination microscopy (SIM) for the accurate mapping of complex lipid bilayers that consist of a synthetic fraction and a fraction of lipids derived from Escherichia coli outer membrane vesicles (OMVs). We exploit the high resolution and molecular specificity that SIM can offer to identify areas of interest in these bilayers and the enhanced resolution that AFM provides to create detailed topography maps of the bilayers. We are thus able to understand the way in which the two different lipid fractions (natural and synthetic) mix within the bilayers, and we can quantify the amount of bacterial membrane incorporated into the bilayer. We prove the system's tunability by generating bilayers made using OMVs engineered to contain a green fluorescent protein (GFP) binding nanobody fused with the porin OmpA. We are able to directly visualize protein-protein interactions between GFP and the nanobody complex. Our work sets the foundation for accurately understanding the composition and properties of OMV-derived SLBs to generate a high-resolution platform for investigating bacterial membrane interactions for the development of next-generation antibiotics.

Organic Bioelectronics for In Vitro Systems.

Bioelectronics have made strides in improving clinical diagnostics and precision medicine. The potential of bioelectronics for bidirectional interfacing with biology through continuous, label-free monitoring on one side and precise control of biological activity on the other has extended their application scope to in vitro systems. The advent of microfluidics and the considerable advances in reliability and complexity of in vitro models promise to eventually significantly reduce or replace animal studies, currently the gold standard in drug discovery and toxicology testing. Bioelectronics are anticipated to play a major role in this transition offering a much needed technology to push forward the drug discovery paradigm. Organic electronic materials, notably conjugated polymers, having demonstrated technological maturity in fields such as solar cells and light emitting diodes given their outstanding characteristics and versatility in processing, are the obvious route forward for bioelectronics due to their biomimetic nature, among other merits. This review highlights the advances in conjugated polymers for interfacing with biological tissue in vitro, aiming ultimately to develop next generation in vitro systems. We showcase in vitro interfacing across multiple length scales, involving biological models of varying complexity, from cell components to complex 3D cell cultures. The state of the art, the possibilities, and the challenges of conjugated polymers toward clinical translation of in vitro systems are also discussed throughout.

Dual Mode Sensing of Binding and Blocking of Cancer Exosomes to Biomimetic Human Primary Stem Cell Surfaces.

Cancer-derived exosomes (cEXOs) facilitate transfer of information between tumor and human primary stromal cells, favoring cancer progression. Although the mechanisms used during this information exchange are still not completely understood, it is known that binding is the initial contact established between cEXOs and cells. Hence, studying binding and finding strategies to block it are of great therapeutic value. However, such studies are challenging for a variety of reasons, including the need for human primary cell culture, the difficulty in decoupling and isolating binding from internalization and cargo delivery, and the lack of techniques to detect these specific interactions. In this work, we created a supported biomimetic stem cell membrane incorporating membrane components from human primary adipose-derived stem cells (ADSCs). We formed the supported membrane on glass and on multielectrode arrays to offer the dual option of optical or electrical detection of cEXO binding to the membrane surface. Using our platform, we show that cEXOs bind to the stem cell membrane and that binding is blocked when an antibody to integrin ß1, a component of ADSC surface, is exposed to the membrane surface prior to cEXOs. To test the biological outcome of blocking this interaction, we first confirm that adding cEXOs to cultured ADSCs leads to the upregulation of vascular endothelial growth factor, a measure of proangiogenic activity. Next, when ADSCs are first blocked with anti-integrin ß1 and then exposed to cEXOs, the upregulation of proangiogenic activity and cell proliferation are significantly reduced. This biomimetic membrane platform is the first cell-free label-free in vitro platform for the recapitulation and study of cEXO binding to human primary stem cells with potential for therapeutic molecule screening as it is compatible with scale-up and multiplexing.

Functional Infectious Nanoparticle Detector: Finding Viruses by Detecting Their Host Entry Functions Using Organic Bioelectronic Devices.

Emerging viruses will continue to be a threat to human health and wellbeing into the foreseeable future. The COVID-19 pandemic revealed the necessity for rapid viral sensing and inhibitor screening in mitigating viral spread and impact. Here, we present a platform that uses a label-free electronic readout as well as a dual capability of optical (fluorescence) readout to sense the ability of a virus to bind and fuse with a host cell membrane, thereby sensing viral entry. This approach introduces a hitherto unseen level of specificity by distinguishing fusion-competent viruses from fusion-incompetent viruses. The ability to discern between competent and incompetent viruses means that this device could also be used for applications beyond detection, such as screening antiviral compounds for their ability to block virus entry mechanisms. Using optical means, we first demonstrate the ability to recapitulate the entry processes of influenza virus using a biomembrane containing the viral receptor that has been functionalized on a transparent organic bioelectronic device. Next, we detect virus membrane fusion, using the same, label-free devices. Using both reconstituted and native cell membranes as materials to functionalize organic bioelectronic devices, configured as electrodes and transistors, we measure changes in membrane properties when virus fusion is triggered by a pH drop, inducing hemagglutinin to undergo a conformational change that leads to membrane fusion.

Insights into the toxicity of biomaterials microparticles with a combination of cellular and oxidative biomarkers.

Considering that the extensive biomedical, pharmaceutics, cosmetic and other industrial applications of biomaterials (BMs) is of great concern nowadays, regarding their environmental risk, the present study aimed to investigate the effects of four BMs, poly(ε-caprolactone) (PCL), poly(butylene succinate) (PBSu), chitosan (CS) and modified chitosan (succinic acid grafted chitosan) (CS-Suc) in the form of microplastics (particle sizes less than 1 mm) on biochemical parameters of snails Cornu aspersum hemocytes. Due to the absence of knowledge about the environmentally relevant concentrations of BMs, snails were initially treated through their food with a wide range of nominal concentrations of each BM to define the half maximal effective concentration (NRRT50), according to the destabilization degree of hemocytes' lysosomal membranes (by mean of neutral red retention time/NRRT assay). Thereafter, snails were treated with each BM, at concentrations lower than the estimated NRRT50 values in all cases, for periods up to 15 days. After the end of the exposure period, a battery of stress indices were measured in hemocytes of challenged snails. According to the results, all parameters tested in BMs-treated snails statistically differed from those measured in BMs-free snails, thus indicating the pro-oxidant potential of BMs, as well as their ability to affect animals' physiology. The most considerable effect in most cases seems to be caused by modified chitosan and PCL, while chitosan appears to be the least toxic. A common response mechanism of snails' blood cells against the 4 BMs used in the present study was shown. After exposure to each of the studied BMs a significant augmentation in protein carbonyls, MDA equivalents and DNA damage, while a significant reduction in NRRT values was determined in the snails hemocytes, in relation to the unexposed animals. From the biochemical parameters examined, MDA equivalents and DNA damage seem to be more susceptible than the other parameters studied, to respond to BMs effect, with MDA to react with more sensitivity to PCL and CS, while DNA damage to CS-Suc and PBSu. Our results could suggest the simultaneous use of the latter biomarkers in biomonitoring studies of terrestrial ecosystems against the specific BMs.

Detection of Ganglioside-Specific Toxin Binding with Biomembrane-Based Bioelectronic Sensors.

Gangliosides, glycolipids that are abundant in the plasma membrane outer leaflet, play an integral role in cellular recognition, adhesion, and infection by interacting with different endogenous molecules, viruses, and toxins. Model membrane systems, such as ganglioside-enriched supported lipid bilayers (SLBs), present a useful tool for sensing, characterizing, and quantifying such interactions. In this work, we report the formation of ganglioside GM1-rich SLBs on conducting polymer electrodes using a solvent-assisted lipid bilayer assembly method to investigate changes in membrane electrical properties upon binding of the B subunit of cholera toxin. The sensing capabilities of our platform were investigated by varying both the receptor and the toxin concentrations in the system as well as using a complex sample (milk contaminated with the toxin) and monitoring the changes in the electrical properties of the membrane. Our work highlights the potential of such conducting polymer-supported biomembrane-based platforms for detecting the toxins within a complex environment, studying ganglioside-specific biomolecular interactions with toxins and screening inhibitory molecules to prevent these interactions.

Optical and Electronic Ion Channel Monitoring from Native Human Membranes.

Transmembrane proteins represent a major target for modulating cell activity, both in terms of therapeutics drugs and for pathogen interactions. Work on screening such therapeutics or identifying toxins has been severely limited by the lack of available methods that would give high content information on functionality (ideally multimodal) and that are suitable for high-throughput. Here, we have demonstrated a platform that is capable of multimodal (optical and electronic) screening of ligand gated ion-channel activity in human-derived membranes. The TREK-1 ion-channel was expressed within supported lipid bilayers, formed via vesicle fusion of blebs obtained from the HEK cell line overexpressing TREK-1. The resulting reconstituted native membranes were confirmed via fluorescence recovery after photobleaching to form mobile bilayers on top of films of the polymeric electroactive transducer poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS). PEDOT:PSS electrodes were then used for quantitative electrochemical impedance spectroscopy measurements of ligand-mediated TREK-1 interactions with two compounds, spadin and arachidonic acid, known to suppress and activate TREK-1 channels, respectively. PEDOT:PSS-based organic electrochemical transistors were then used for combined optical and electronic measurements of TREK-1 functionality. The technology demonstrated here is highly promising for future high-throughput screening of transmembrane protein modulators owing to the robust nature of the membrane integrated device and the highly quantitative electrical signals obtained. This is in contrast with live-cell-based electrophysiology assays (e.g., patch clamp) which compare poorly in terms of cost, usability, and compatibility with optical transduction.

Self-Assembly of Mammalian-Cell Membranes on Bioelectronic Devices with Functional Transmembrane Proteins.

Transmembrane proteins (TMPs) regulate processes occurring at the cell surface and are essential gatekeepers of information flow across the membrane. TMPs are difficult to study, given the complex environment of the membrane and its influence on protein conformation, mobility, biomolecule interaction, and activity. For the first time, we create mammalian biomembranes supported on a transparent, electrically conducting polymer surface, which enables dual electrical and optical monitoring of TMP function in its native membrane environment. Mammalian plasma membrane vesicles containing ATP-gated P2X2 ion channels self-assemble on a biocompatible polymer cushion that transduces the changes in ion flux during ATP exposure. This platform maintains the complexity of the native plasma membrane, the fluidity of its constituents, and protein orientation critical to ion channel function. We demonstrate the dual-modality readout using microscopy to characterize protein mobility by single-particle tracking and sensing of ATP gating of P2X2 using electrical impedance spectroscopy. This measurement of TMP activity important for pain sensing, neurological activity, and sensory activity raises new possibilities for drug screening and biosensing applications.

Biomembrane-based organic electronic devices for ligand-receptor binding studies.

We present a simple, rapid method for forming supported lipid bilayers on organic electronic devices composed of conducting polymer electrodes using a solvent-assisted lipid bilayer formation method. These supported bilayers present protein recognition elements that are mobile, critical for multivalent binding interactions. Because these polymers are transparent and conducting, we demonstrate, by optical and electrical detection, the specific interactions of proteins with these biomembrane-based bioelectronic devices. This work paves the way for easy formation of biomembrane mimetics for sensing and detection of binding events in a label-free manner on organic electronic devices of more sophisticated architectures. Graphical abstract.

A highly sensitive molecular structural probe applied to in situ biosensing of metabolites using PEDOT:PSS.

A large amount of research within organic biosensors is dominated by organic electrochemical transistors (OECTs) that use conducting polymers such as poly(3,4-ethylene dioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS). Despite the recent advances in OECT-based biosensors, the sensing is solely reliant on the amperometric detection of the bioanalytes. This is typically accompanied by large undesirable parasitic electrical signals from the electroactive components in the electrolyte. Herein, we present the use of in situ resonance Raman spectroscopy to probe subtle molecular structural changes of PEDOT:PSS associated with its doping level. We demonstrate how such doping level changes of PEDOT:PSS can be used, for the first time, on operational OECTs for sensitive and selective metabolite sensing while simultaneously performing amperometric detection of the analyte. We test the sensitivity by molecularly sensing a lowest glucose concentration of 0.02 mM in phosphate-buffered saline solution. By changing the electrolyte to cell culture media, the selectivity of in situ resonance Raman spectroscopy is emphasized as it remains unaffected by other electroactive components in the electrolyte. The application of this molecular structural probe highlights the importance of developing biosensing probes that benefit from high sensitivity of the material's structural and electrical properties while being complimentary with the electronic methods of detection.

Facile Generation of Biomimetic-Supported Lipid Bilayers on Conducting Polymer Surfaces for Membrane Biosensing.

Membrane biosensors that can rapidly sense pathogen interaction and disrupting agents are needed to identify and screen new drugs to combat antibiotic resistance. Bioelectronic devices have the capability to read out both ionic and electrical signals, but their compatibility with biological membranes is somewhat limited. Supported lipid bilayers (SLBs) have served as useful biomimetics for a myriad of research topics involving biological membranes. However, SLBs are traditionally made on inert, rigid, inorganic surfaces. Here, we demonstrate a versatile and facile method for generating SLBs on a conducting polymer device using a solvent-assisted lipid bilayer (SALB) technique. We use this bioelectronic device to form both mammalian and bacterial membrane mimetics to sense the membrane interactions with a bacterial toxin (α-hemolysin) and an antibiotic compound (polymyxin B), respectively. Our results show that we can form high quality bilayers of both types and sense these particular interactions with them, discriminating between pore formation, in the case of α-hemolysin, and disruption of the bilayer, in the case of polymyxin B. The SALB formation method is compatible with many membrane compositions that will not form via common vesicle fusion methods and works well in microfluidic devices. This, combined with the massive parallelization possible for the fabrication of electronic devices, can lead to miniaturized multiplexed devices for rapid data acquisition necessary to identify antibiotic targets that specifically disrupt bacterial, but not mammalian membranes, or identify bacterial toxins that strongly interact with mammalian membranes.

Electrophoretic drug delivery for seizure control.

The persistence of intractable neurological disorders necessitates novel therapeutic solutions. We demonstrate the utility of direct in situ electrophoretic drug delivery to treat neurological disorders. We present a neural probe incorporating a microfluidic ion pump (µFIP) for on-demand drug delivery and electrodes for recording local neural activity. The µFIP works by electrophoretically pumping ions across an ion exchange membrane and thereby delivers only the drug of interest and not the solvent. This "dry" delivery enables precise drug release into the brain region with negligible local pressure increase. The therapeutic potential of the µFIP probe is tested in a rodent model of epilepsy. The µFIP probe can detect pathological activity and then intervene to stop seizures by delivering inhibitory neurotransmitters directly to the seizure source. We anticipate that further tailored engineering of the µFIP platform will enable additional applications in neural interfacing and the treatment of neurological disorders.