Exploring Photoswitchable Binding Interactions with Small-Molecule- and Peptide-Based Inhibitors of Trypsin.

The ability to photochemically activate a drug, both when and where needed, requires optimisation of the difference in biological activity between each isomeric state. As a step to this goal, we report small-molecule- and peptide-based inhibitors of the same protease-trypsin-to better understand how photoswitchable drugs interact with their biological target. The best peptidic inhibitor displayed a more than fivefold difference in inhibitory activity between isomeric states, whereas the best small-molecule inhibitor only showed a 3.4-fold difference. Docking and molecular modelling suggest this result is due to a large change in 3D structure in the key binding residues of the peptidic inhibitor upon isomerisation; this is not observed for the small-molecule inhibitor. Hence, we demonstrate that significant structural changes in critical binding motifs upon irradiation are essential for maximising the difference in biological activity between isomeric states. This is an important consideration in the design of future photoswitchable drugs for clinical applications.

The relationships between organizational culture and thriving at work among nurses: The mediating role of affective commitment and work engagement.

AIM: Guided by the social embeddedness model of thriving at work, this paper explores how nursing organizational culture, work engagement and affective commitment affect nurses' thriving at work. BACKGROUND: Thriving at work has implications for better employee and organization outcomes. The antecedents of thriving at work among the nursing population needs to be expanded by analysing the cross-level impact of organizational and individual characteristics. METHODS: A cross-sectional design was used to collect data from 1437 frontline nurses in a tertiary teaching hospital in China between April and May 2020 through an online survey about perceived nursing culture, work engagement, affective commitment and thriving at work. Data were analysed using SPSS, and a structural equation model was established using the PROCESS macro. RESULTS: Our results showed that work engagement and affective commitment mediated the relationship between nurses' perceived nursing culture and their thriving at work. Among nurses, work engagement was positively correlated to affective commitment. CONCLUSION: Our study confirmed the social embeddedness model of thriving at work by showing that both contextual and dispositional factors can influence nurses' thriving at work. Nurse leaders can foster nursing staff's thriving at work by building an inclusive work environment and by providing adequate resources to staff. Future research is needed to elaborate on employee and organizational outcomes associated with thriving at work. IMPACT: Nurse leaders should be the advocate for nurses to improve their organizational identification, fostering their thriving at work. Individual nurses can also take an active role in developing work-related resources to sustain their thriving through self-adaption processes. Collective thriving in the nursing workforce is needed to overcome adversity and hardship in the ever-changing and increasingly demanding health care industry and to further contribute to the vitality of the broader social and public environments. PATIENT OR PUBLIC CONTRIBUTION: No patient or public contribution. This study did not involve patients, service users, caregivers or members of the public.

Progress in Solid Polymer Electrolytes for Lithium-Ion Batteries and Beyond.

Solid-state polymer electrolytes (SPEs) for high electrochemical performance lithium-ion batteries have received considerable attention due to their unique characteristics; they are not prone to leakage, and they exhibit low flammability, excellent processability, good flexibility, high safety levels, and superior thermal stability. However, current SPEs are far from commercialization, mainly due to the low ionic conductivity, low Li+ transference number (tLi+ ), poor electrode/electrolyte interface contact, narrow electrochemical oxidation window, and poor long-term stability of Li metal. Recent work on improving electrochemical performance and these aspects of SPEs are summarized systematically here with a particular focus on the underlying mechanisms, and the improvement strategies are also proposed. This review could lead to a deeper consideration of the issues and solutions affecting the application of SPEs and pave a new pathway to safe, high-performance lithium-ion batteries.

A Multichannel Flexible Optoelectronic Fiber Device for Distributed Implantable Neurological Stimulation and Monitoring.

Optical fibers made of polymeric materials possess high flexibility that can potentially integrate with flexible electronic devices to realize complex functions in biology and neurology. Here, a multichannel flexible device based on four individually addressable optical fibers transfer-printed with flexible electronic components and controlled by a wireless circuit is developed. The resulting device offers excellent mechanics that is compatible with soft and curvilinear tissues, and excellent diversity through switching different light sources. The combined configuration of optical fibers and flexible electronics allows optical stimulation in selective wavelengths guided by the optical fibers, while conducting distributed, high-throughput biopotential sensing using the flexible microelectrode arrays. The device has been demonstrated in vivo with rats through optical stimulation and simultaneously monitoring of spontaneous/evoked spike signals and local field potentials using 32 microelectrodes in four brain regions. Biocompatibility of the device has been characterized by behavior and immunohistochemistry studies, demonstrating potential applications of the device in long-term animal studies. The techniques to integrate flexible electronics with optical fibers may inspire the development of more flexible optoelectronic devices for sophisticated applications in biomedicine and biology.

Rationally designed peptide-based inhibitor of Aß42 fibril formation and toxicity: a potential therapeutic strategy for Alzheimer's disease.

Amyloid beta peptide (Aß42) aggregation in the brain is thought to be responsible for the onset of Alzheimer's disease, an insidious condition without an effective treatment or cure. Hence, a strategy to prevent aggregation and subsequent toxicity is crucial. Bio-inspired peptide-based molecules are ideal candidates for the inhibition of Aß42 aggregation, and are currently deemed to be a promising option for drug design. In this study, a hexapeptide containing a self-recognition component unique to Aß42 was designed to mimic the ß-strand hydrophobic core region of the Aß peptide. The peptide is comprised exclusively of D-amino acids to enhance specificity towards Aß42, in conjunction with a C-terminal disruption element to block the recruitment of Aß42 monomers on to fibrils. The peptide was rationally designed to exploit the synergy between the recognition and disruption components, and incorporates features such as hydrophobicity, ß-sheet propensity, and charge, that all play a critical role in the aggregation process. Fluorescence assays, native ion-mobility mass spectrometry (IM-MS) and cell viability assays were used to demonstrate that the peptide interacts with Aß42 monomers and oligomers with high specificity, leading to almost complete inhibition of fibril formation, with essentially no cytotoxic effects. These data define the peptide-based inhibitor as a potentially potent anti-amyloid drug candidate for this hitherto incurable disease.

Unravelling electron transfer in peptide-cation complexes: a model for mimicking redox centres in proteins.

Metalloproteins are crucial to many biological processes, such as photosynthesis, respiration, and efficient electron transport. Zinc is the most common transition metal found in proteins and is critical for structure, function and stability, however the effects from the electronic properties of a bound zinc ion on electron transfer are not clearly defined. Here, a series of ß-strand and 310-helical peptides, capable of binding Zn2+via suitably positioned His residues, was synthesized and their ability to undergo electron transfer in the presence and absence of Zn2+ studied by electrochemical and computational means. The ß-strand peptide was shown to be conformationally pre-organized, with this geometry maintained on complexation with zinc. Electrochemical studies show a significant increase in charge transport, following binding of the zinc ion to the ß-strand peptide. In contrast, complexation of zinc to the helical peptide disrupts the intramolecular hydrogen bonding network known to facilitate electron transfer and leads to a loss of secondary structure, resulting in a decrease in charge transfer. These experimental and computational studies reveal an interplay, which demonstrates that bound zinc enhances charge transfer by changing the electronic properties of the peptide, and not simply by influencing secondary structure.

Unravelling Structural Dynamics within a Photoswitchable Single Peptide: A Step Towards Multimodal Bioinspired Nanodevices.

The majority of the protein structures have been elucidated under equilibrium conditions. The aim herein is to provide a better understanding of the dynamic behavior inherent to proteins by fabricating a label-free nanodevice comprising a single-peptide junction to measure real-time conductance, from which their structural dynamic behavior can be inferred. This device contains an azobenzene photoswitch for interconversion between a well-defined cis, and disordered trans isomer. Real-time conductance measurements revealed three distinct states for each isomer, with molecular dynamics simulations showing each state corresponds to a specific range of hydrogen bond lengths within the cis isomer, and specific dihedral angles in the trans isomer. These insights into the structural dynamic behavior of peptides may rationally extend to proteins. Also demonstrated is the capacity to modulate conductance which advances the design and development of bioinspired electronic nanodevices.

Peptides as Bio-Inspired Electronic Materials: An Electrochemical and First-Principles Perspective.

Molecular electronics is at the forefront of interdisciplinary research, offering a significant extension of the capabilities of conventional silicon-based technology as well as providing a possible stand-alone alternative. Bio-inspired molecular electronics is a particularly intriguing paradigm, as charge transfer in proteins/peptides, for example, plays a critical role in the energy storage and conversion processes for all living organisms. However, the structure and conformation of even the simplest protein is extremely complex, and therefore, synthetic model peptides comprising well-defined geometry and predetermined functionality are ideal platforms to mimic nature for the elucidation of fundamental biological processes while also enhancing the design and development of single-peptide electronic components. In this Account, we first present intramolecular electron transfer within two synthetic peptides, one with a well-defined helical conformation and the other with a random geometry, using electrochemical techniques and computational simulations. This study reveals two definitive electron transfer pathways (mechanisms), the natures of which are dependent on secondary structure. Following on from this, electron transfer within a series of well-defined helical peptides, constrained by either Huisgen cycloaddition, ring-closing metathesis, or a lactam bridge, was determined. The electrochemical results indicate that each constrained peptide, in contrast to a linear counterpart, exhibits a remarkable shift of the formal potential to the positive (>460 mV) and a significant reduction of the electron transfer rate constant (up to 15-fold), which represent two distinct electronic "on/off" states. High-level calculations demonstrate that the additional backbone rigidity provided by the side-bridge constraints leads to an increased reorganization energy barrier, which impedes the vibrational fluctuations necessary for efficient intramolecular electron transfer through the peptide backbone. Further calculations reveal a clear mechanistic transition from hopping to superexchange (tunneling) stemming from side-bridge gating. We then extended our research to fine-tuning of the electronic properties of peptides through both structural and chemical manipulation, to reveal an interplay between electron-rich side chains and backbone rigidity on electron transfer. Further to this, we explored the possibility that the side-bridge constraints present in our synthetic peptides provide an additional electronic transport pathway, which led to the discovery of two distinct forms of quantum interferometer. The effects of destructive quantum interference appear essentially through both the backbone and an alternative tunneling pathway provided by the side bridge in the constrained ß-strand peptide, as evidenced by a correlation between electrochemical measurements and conductance simulations for both linear and constrained ß-strand peptides. In contrast, an interplay between quantum interference effects and vibrational fluctuations is revealed in the linear and constrained 310-helical peptides. Collectively, these exciting findings augment our fundamental knowledge of charge transfer dynamics and kinetics in peptides and also open up new avenues to design and develop functional bio-inspired electronic devices, such as on/off switches and quantum interferometers, for practical applications in molecular electronics.

Photopharmacological Control of Cyclic Antimicrobial Peptides.

Gramicidin S is a naturally occurring antimicrobial cyclic peptide. Herein, we present a series of cyclic peptides based on gramicidin S that contain an azobenzene photoswitch to reversibly control secondary structure and, hence, antimicrobial activity. 1 H NMR spectroscopy and density functional theory calculations revealed a ß-sheet/ß-turn secondary structure for the cis configuration of each peptide, and an ill-defined conformation for all associated trans structures. The cis-enriched and trans-enriched photostationary states (PSSs) for peptides 1-3 were assayed against Staphylococcus aureus to reveal a clear relationship between well-defined secondary structure, amphiphilicity and optimal antimicrobial activity. Most notably, peptides 2 a and 2 b exhibited a fourfold difference in antimicrobial activity in the cis-enriched PSS over the trans-enriched equivalent. This photopharmacological approach allows antimicrobial activity to be regulated through photochemical control of the azobenzene photoswitch, thereby opening new avenues in the design and synthesis of future antibiotics.

Peptides as Bio-inspired Molecular Electronic Materials.

Understanding the electronic properties of single peptides is not only of fundamental importance to biology, but it is also pivotal to the realization of bio-inspired molecular electronic materials. Natural proteins have evolved to promote electron transfer in many crucial biological processes. However, their complex conformational nature inhibits a thorough investigation, so in order to study electron transfer in proteins, simple peptide models containing redox active moieties present as ideal candidates. Here we highlight the importance of secondary structure characteristic to proteins/peptides, and its relevance to electron transfer. The proposed mechanisms responsible for such transfer are discussed, as are details of the electrochemical techniques used to investigate their electronic properties. Several factors that have been shown to influence electron transfer in peptides are also considered. Finally, a comprehensive experimental and theoretical study demonstrates that the electron transfer kinetics of peptides can be successfully fine tuned through manipulation of chemical composition and backbone rigidity. The methods used to characterize the conformation of all peptides synthesized throughout the study are outlined, along with the various approaches used to further constrain the peptides into their geometric conformations. The aforementioned sheds light on the potential of peptides to one day play an important role in the fledgling field of molecular electronics.

Up-regulation of 14-3-3ζ expression in intrahepatic cholangiocarcinoma and its clinical implications.

The 14-3-3 proteins are highly conserved molecules that are involved in many vital biologic processes and are associated with the progression of cancer. The role of 14-3-3ζ, a dimeric isoform of 14-3-3, in intrahepatic cholangiocarcinoma (ICC) was investigated in this study. The expression of 14-3-3ζ in tumour samples from patients with ICC was examined by Western blot and immunohistochemistry, and the correlation between its expression and various clinicopathological features was determined. Then, the capacity for invasion, migration and proliferation as well as the expression of epithelial-mesenchymal transition (EMT)-related markers in ICC cells were assessed after 14-3-3ζ depletion. Finally, the prognostic significance of 14-3-3ζ in patients with ICC was further evaluated by Kaplan-Meier and Cox regression analyses. The expression of 14-3-3ζ was significantly higher in ICC tissues compared to peritumoural tissues. High expression of 14-3-3ζ positively correlated with lymphatic metastasis and tumour-node-metastasis (TNM) stage. The inhibition of 14-3-3ζ expression was able to impair the invasion, migration and proliferation of ICC cells in vitro. The expression of 14-3-3ζ was significantly correlated with the expression of the EMT-related markers snail and E-cadherin in ICC samples. Moreover, the down-regulation of 14-3-3ζ also decreased the phosphorylation of extracellular signal-regulated kinase (ERK) in ICC cells. Clinically, patients with ICC with high 14-3-3ζ expression demonstrated a poor prognosis in terms of a short overall survival and a high recurrence rate of the disease. A multivariate analysis revealed that 14-3-3ζ overexpression was an independent prognostic indicator for patients with ICC. 14-3-3ζ may enhance the invasive and proliferative capacity of tumour cells and thus prompt the progression of ICC via the activation of ERK signalling and the induction of EMT. The overexpression of 14-3-3ζ may be used as a prognostic biomarker and therapeutic target in patients with ICC.

The correlation of electrochemical measurements and molecular junction conductance simulations in ß-strand peptides.

Understanding the electronic properties of single peptides is not only of fundamental importance, but it is also paramount to the realization of peptide-based molecular electronic components. Electrochemical and theoretical studies are reported on two ß-strand-based peptides, one with its backbone constrained with a triazole-containing tether introduced by Huisgen cycloaddition (peptide 1) and the other a direct linear analogue (peptide 2). Density functional theory (DFT) and non-equilibrium Green's function were used to investigate conductance in molecular junctions containing peptides 3 and 4 (analogues of 1 and 2). Although the peptides share a common ß-strand conformation, they display vastly different electronic transport properties due to the presence (or absence) of the side-bridge constraint and the associated effect on backbone rigidity. These studies reveal that the electron transfer rate constants of 1 and 2, and the conductance calculated for 3 and 4, differ by approximately one order of magnitude, thus providing two distinctly different conductance states and what is essentially a molecular switch. A definitive correlation of electrochemical measurements and molecular junction conductance simulations is demonstrated using two different charge transfer techniques. This study furthers our understanding of the electronic properties of peptides at the molecular level, which provides an opportunity to fine-tune their molecular orbital energies through suitable structural manipulation.

Unraveling the interplay of backbone rigidity and electron rich side-chains on electron transfer in peptides: the realization of tunable molecular wires.

Electrochemical studies are reported on a series of peptides constrained into either a 310-helix (1-6) or ß-strand (7-9) conformation, with variable numbers of electron rich alkene containing side chains. Peptides (1 and 2) and (7 and 8) are further constrained into these geometries with a suitable side chain tether introduced by ring closing metathesis (RCM). Peptides 1, 4 and 5, each containing a single alkene side chain reveal a direct link between backbone rigidity and electron transfer, in isolation from any effects due to the electronic properties of the electron rich side-chains. Further studies on the linear peptides 3-6 confirm the ability of the alkene to facilitate electron transfer through the peptide. A comparison of the electrochemical data for the unsaturated tethered peptides (1 and 7) and saturated tethered peptides (2 and 8) reveals an interplay between backbone rigidity and effects arising from the electron rich alkene side-chains on electron transfer. Theoretical calculations on ß-strand models analogous to 7, 8 and 9 provide further insights into the relative roles of backbone rigidity and electron rich side-chains on intramolecular electron transfer. Furthermore, electron population analysis confirms the role of the alkene as a "stepping stone" for electron transfer. These findings provide a new approach for fine-tuning the electronic properties of peptides by controlling backbone rigidity, and through the inclusion of electron rich side-chains. This allows for manipulation of energy barriers and hence conductance in peptides, a crucial step in the design and fabrication of molecular-based electronic devices.

Impedance nanopore biosensor: influence of pore dimensions on biosensing performance.

Knowledge about electrochemical and electrical properties of nanopore structures and the influence of pore dimensions on these properties is important for the development of nanopore biosensing devices. The aim of this study was to explore the influence of nanopore dimensions (diameter and length) on biosensing performance using non-faradic electrochemical impedance spectroscopy (EIS). Nanoporous alumina membranes (NPAMs) prepared by self-ordered electrochemical anodization of aluminium were used as model nanopore sensing platforms. NPAMs with different pore diameters (25-65 nm) and lengths (4-18 µm) were prepared and the internal pore surface chemistry was modified by covalently attaching streptavidin and biotin. The performance of this antibody nanopore biosensing platform was evaluated using various concentrations of biotin as a model analyte. EIS measurements of pore resistivity and conductivity were carried out for pores with different diameters and lengths. The results showed that smaller pore dimensions of 25 nm and pore lengths up to 10 µm provide better biosensing performance.

Symptoms experienced after transcatheter arterial chemoembolization in patients with primary liver cancer: A network analysis.

Objective: This study aimed to establish a symptom network for patients with primary liver cancer posttranscatheter arterial chemoembolization (TACE), identifying core and bridge symptoms. The goal is to provide a foundation for precise and comprehensive nursing interventions. Methods: A total of 1207 post-TACE patients were included using a consecutive sampling method. Data collection involved a general information questionnaire, the Anderson Symptom Assessment Scale, and a primary liver cancer-specific symptom module. The symptom network was constructed using the R language. Results: In the overall network, distress exhibited the highest strength (rs = 1.31) and betweenness (rb = 62). Fatigue had the greatest closeness (rc = 0.0043), while nausea and vomiting (r = 0.76 ± 0.02) had the highest marginal weights. Nausea had the highest bridge strength (rbs = 5.263). In the first-time TACE-treated symptom network, sadness (rbs = 5.673) showed the highest bridge strength, whereas in the non-first-time symptom network, fever (rbs = 3.061) had the highest bridge strength. Conclusions: Distress serves as a core symptom, and nausea acts as a bridge symptom after TACE treatment in liver cancer patients. Interventions targeting bridge symptoms should be tailored based on the number of treatments, enhancing the quality of symptom management.

A New Gramicidin S Analogue with Potent Antibacterial Activity and Negligible Hemolytic Toxicity.

Antibiotic resistance is an urgent threat to global health, with the decreasing efficacy of conventional drugs underscoring the urgency for innovative therapeutic strategies. Antimicrobial peptides present as promising alternatives to conventional antibiotics. Gramicidin S is one such naturally occurring antimicrobial peptide that is effective against Staphylococcus aureus, with a minimum inhibitory concentration (MIC) of 4 µg/mL (3.6 µM). Despite this potent activity, its significant hemolytic toxicity restricts its clinical use to topical applications. Herein, we present rational modifications to the key ß-strand and ß-turn regions of gramicidin S to concurrently mitigate hemolytic effects, while maintaining potency. Critically, peptide 9 displayed negligible hemolytic toxicity, while possessing significant antibacterial potency against a panel of methicillin-sensitive and methicillin-resistant S. aureus clinical isolates (MIC of 8 µg/mL, 7.2 µM). Given the substantial antibacterial activity and near absence of cytotoxicity, 9 presents as a potential candidate for systemic administration in the treatment of S. aureus bacteremia/sepsis.

Full Potential Catalysis of Co0.4Ni1.6P-V/CNT with Phosphorus Vacancies for Li2S1-2 Deposition/Decomposition and S8/Li2Sn (3 ≤ n ≤ 8) Conversion in Li-S Batteries.

The slow kinetics of polysulfide conversions hinders the commercial progress of Li-S batteries. The introduction of high-efficiency catalysts accelerates heterogeneous reactions and enhances the utilization of S. The full potential of the Co0.4Ni1.6P-V/CNT-modified separator catalyzes the all-process reactions of the S electrode and increases the rates and cycling lives of the batteries. The two-site synergistic effect of Co0.4Ni1.6P-V/CNT regulates the catalytic activity, and the phosphorus vacancies enrich the active sites. The higher electron density at the Co and Ni double sites increases chemisorption of the Co0.4Ni1.6P-V/CNT on Li2Sn (1 ≤ n ≤ 4), stretches and breaks the Li-S and Ni-S bonds during Li2S decomposition, and reduces the energy barrier for Li2S decomposition. The cyclic voltammograms of the asymmetric batteries demonstrated that Co0.4Ni1.6P-V/CNT also catalyzed the Li2Sn ⇌ S8 (3 ≤ n ≤ 8) reaction, realizing the full catalytic potential of the Li-S batteries. Increased Li+ diffusion/migration in the Co0.4Ni1.6P-V/CNT-modified separator ensured fast electrochemical reactions. The excellent catalytic effect of Co0.4Ni1.6P-V/CNT provided smaller polarization and superior rate performance, which led to high discharge specific capacities of 1511.9, 1172.6, 1006.0, 881.0, and 785.7 mA h g-1 at current densities of 0.1, 0.2, 0.5, 1, and 2 mA cm-2 with sulfur loadings of 7.98 mg cm-2, respectively. This approach involving simple crystal modulation and introduction of defects provides a new way to achieve the full catalytic potential of Li-S batteries.

Unveiling microplastics from zippers: Characterisation and visualisation through Raman imaging analysis.

Microplastics have emerged as a global concern due to the increased plastic contamination found in a variety of sources. Herein we unveil microplastics released from plastic zippers that can generally be found in our clothes and textiles. We first employ a scanning electron microscope (SEM) to visualise the scratches developed on the zipper teeth and the derived particles. We then use Raman imaging to identify and simultaneously visualise the plastics from the chemical or molecular spectrum window. Based on hundreds to thousands of spectra, rather than a single spectrum or even a single peak that works as just a pixel in the image, imaging analysis can significantly increase the signal-to-noise ratio. Furthermore, the non-uniform distribution of components or multi-components can also be effectively imaged to avoid the possible bias from the single-spectrum analysis. The challenge to convert the hundreds to thousands of spectra of a hyperspectral matrix to an image is also discussed, and chemometrics is adopted and recommended to further improve the signal-to-noise ratio. The co-ingredient of titanium oxide in the zipper teeth/sewing lines is also effectively identified by Raman imaging. Based on the effective characterisation, we estimate that up to ~410 microplastics could be potentially released during each time of on-off zipping, although the variation can be expected and depends on several other factors. This study reminds us to be aware of the potential contamination derived from similar types of microplastic sources in our daily lives.

External validation of postoperative nausea and vomiting risk scores in patients with liver cancer: A single-centre prospective cohort study.

OBJECTIVES: This study aimed to test the external validity of postoperative nausea and vomiting (PONV) risk assessment tools in patients undergoing hepatectomy, and to guide healthcare professionals' assessment of postoperative patients. BACKGROUND: The identification of PONV risk is particularly important in the context of prevention. However, the predictive performance of the current PONV risk scores has not been confirmed in patients with liver cancer, and its applicability is still unknown. These uncertainties pose difficulties in performing routine risk assessment of PONV for patients with liver cancer in a clinical practice setting. METHODS: Patients diagnosed with liver cancer and undergoing hepatectomy were prospectively consecutively recruited. All enrolled patients received PONV assessments and PONV risk assessments via the Apfel risk score and the Koivuranta risk score. Receiver operating characteristic curves (ROC curves) and calibration curves were used to assess the external validity. This study was reported according to the TRIPOD Checklist. RESULTS: Among 214 PONV-assessed patients, 114 patients (53.3%) developed PONV. For the Apfel simplified risk score, the ROC area was 0.612 (95% confidence interval [CI]: 0.543-0.678) in the validation dataset, which demonstrated imperfect discrimination; the calibration curve showed poor calibration with a slope of 0.49. For the Koivuranta score, the ROC area was 0.628 (CI: 0.559-0.693) in the validation dataset, which showed limited discrimination; the calibration curve indicated an unsatisfactory calibration with a slope of 0.71. CONCLUSIONS: The Apfel risk score and the Koivuranta risk score were not well validated in our study and disease-specific risk factors should be taken into account when updating or developing PONV risk stratification instruments.

Ratiometric colorimetric detection of fluoride ions using a schiff base sensor: enhancing selectivity and sensitivity for naked-eye analysis.

A Schiff base receptor with an active -NH group was designed and synthesized for the selective and sensitive colorimetric detection of inorganic fluoride (F-) ions in an aqueous medium. The sensitivity of the receptor for F- ions was enhanced by the influence of two electron-withdrawing -NO2 groups at ortho and para positions which result in a vivid color change. The receptor underwent a remarkable color change from light yellow to violet, enabling naked-eye detection of F- ions without the need for spectroscopic equipment. To ensure the structural integrity of the synthesized receptors, prominent spectroscopic techniques such as 1H NMR, FTIR, and GCMS analysis were used for characterization. With a limit of detection (LoD) of 0.0996 ppm, a 1 : 2 stoichiometric binding ratio was observed for receptor and F- ions. The binding mechanism confirmed the deprotonation of the -NH group followed by the formation of -HF2, resulting in an intramolecular charge transfer (ICT) transition, which correlates with UV-vis and 1H NMR titration results. In addition, the proposed binding mechanism of F- ion interaction with the receptor was theoretically validated using DFT and TDDFT calculations. Furthermore, as a real-life implementation of the receptor, quantification of the F- ions present in a commercially available mouthwash was demonstrated. To assess the sensitivity performance, a paper-based dip sensor and a solid substrate sensor by functionalizing the receptor on diatomaceous earth were demonstrated. Finally, sensors were built into smartphones that could recognize the red, green, and blue percentages (RGB%) where each parameter defines the intensity of the color, which could also be used as a supplement to the colorimetric investigations.