Lower Limit Research Articles

Differences in human thermal and physiological responses under corridor and greenway in summer in guangzhou

As urbanization and the heat island effect intensify, comfortable and healthy outdoor micro-environments are particularly important for sustainable urban development, encouraging more outdoor activities. Fewer studies have focused on differences in thermal comfort and thermal physiology of users in potential outdoor open spaces. Therefore, this study aims to examine the differences in thermal comfort and thermal stress among users of common outdoor open shady spaces, contributing towards a better thermal experience and mitigating heat stress. In this study, a field investigation of corridors and greenways was conducted on a campus in Guangzhou in the summer based on subjective questionnaires and objective measurements of thermal environment, and thermal physiological parameters. The results found that people were more likely to experience good thermal comfort and weaker intensity of thermal stress in corridors with significant differences in physiological responses. Furthermore, the upper limit comfort temperatures of the corridor and greenway were 34.0 and 33.4 °C, respectively. In addition, it can be concluded that the corridor was a more optimal space for outdoor shade before evening, whereas the greenway was more optimal in the evening in summer. The findings determine the thermal benchmarks for typical outdoor shady spaces in hot and humid regions in summer, which can help designers create comfortable outdoor public spaces that improve thermal comfort and people's health.

B-type natriuretic peptide informativeness in myocardial revascularization with cardio-pulmonary bypass

The objective was to study the dynamics of B-type natriuretic peptide (BNP) and its relationship with hemodynamic parameters during on-pump coronary artery bypass grafting (CABG), and to evaluate the informativeness of the biomarker as a predictor of myocardial dysfunction.Materials and methods. The study involved 127 patients aged 59 [54–66.75] years with ischemic heart disease who underwent CABG. The BNP blood level was determined in the operating room at stages: I – before surgery (BNP1 ), II – at the end of surgery (BNP2 ). Hemodynamic parameters were analyzed at the same stages. Correlation analysis, logistic regression with the calculation of the odds ratio (OR) and 95% confidence interval (95% CI) and ROC analysis with the calculation of the area under the ROC curve (AUC) were used.Results. BNP1 blood level was 49 [25.6–91.6], BNP2 – 90 [47.8–140.2] pg/ml (p < 0.0001). BNP1 correlated with central venous pressure (CVP) at stage I (rho = 0.212; p = 0.017) and with pulmonary artery wedge pressure (PAWP) at stage II (rho = 0.204; p = 0.045). BNP2 correlated with PAWP at stage II (rho = 0.204; p = 0.045). BNP1 > 52.1 pg/ml was the predictor of ICU length of stay > 24 hours (OR 1.0290, 95% CI 1.0154– 1.0427, p < 0.0001, AUC 0.775), BNP1 > 71 pg/ml was the predictor of inotropic index > 5 c. u. (OR 1.0076, 95% CI 1.0015–1.0138, p = 0.014, AUC 0.705) and BNP1 > 90.8 pg/ml was the predictor of vasoactive inotropic index > 10 c. u. (OR 1.0070, 95% CI 1.0014–1.0126, p = 0.013, AUC 0.727). BNP2 > 67.5 pg/ml was the predictor of ICU length of stay > 24 hours (OR 1.0179, 95% CI 1.0073–1.0287, p < 0.0009, AUC 0.763), BNP2 > 94.3 pg/ml was the predictor of inotropic index > 5 c. u. (OR 1.0063, 95% CI 1.0010–1.0117, p = 0.020, AUC 0.713), BNP2 > 144 pg/ml was the predictor of intra-aortic balloon pumping (OR 1.0037, 95% CI 1 .0000–1.0074, p = 0.048, AUC 0.854), BNP2 > 159 pg/ml was the predictor of vasoactive inotropic index > 10 c. u. (OR 1.0072, 95% CI 1.0006–1.0139, p = 0.033, AUC 0.729) and BNP2 > 161 pg/ml was the predictor of early mortality in the ICU (OR 1.0040, 95% CI 1, 0000-1.0080, p = 0.049, AUC 0.845). Conclusion. In 78.7% of patients undergoing on-pump CABG, BNP blood level does not exceed the upper limit of normal; by the end of surgery, the biomarker level increases by 32.9 [17.7–62.0] pg/ml. Before and at the end of surgery, BNP values are weakly correlated with CVP and PAWP and do not correlate with other hemodynamic parameters. Before surgery, BNP blood level in the range of 52.1–90.8 pg/ml are predictors of ICU stay > 24 hours (AUC 0.775), inotropic scale > 5 (AUC 0.705) and vasoactive-inotropic scale > 10 c. u. (AUC 0.727). At the end of surgery, BNP > 67.5 pg/ml is associated with an ICU stay > 24 hours (AUC 0.763), and BNP > 90.4 pg/ml is associated with inotropic scale > 5 c. u. (AUC 0.713). The BNP, increased to 144.0–161.0 pg/ml, indicates severe myocardial dysfunction, including hemodynamic support with intra-aortic balloon pumping (AUC 0.854), vasoactive-inotropic scale > 10 c. u. (AUC 0.729) and the risk of early mortality in the ICU (AUC 0.845).

“The Blot Inside: Jonathan Lethem’s A Gambler’s Anatomy, Lack, Dissent, and Corporate Power”

ABSTRACT This paper argues that the blot in A Gambler’s Anatomy exists in a long line of deep metaphors in Lethem’s work, an ancestor of “Lack” in As She Climbed Across the Table (1997) and the giant hole in the center of Manhattan in Chronic City. In the context of this story, which casts Stolarsky as the pantomimic capitalist villain, it can be interpreted as an ideological blind spot which prevents the protagonist from recognizing his entrapment in a cycle of economic dependency. Its removal should signal an awakening, therefore, but Lethem resists this move. Instead, Bruno is forced to don a mask and is ensnared within a Stolarsky empire which seems to have no outer limits. Even the anti-capitalist riot in which Bruno becomes involved might well have been orchestrated by the arch-capitalist himself. A Gambler’s Anatomy, then, represents Lethem’s most committed critique of corporate power and asks whether it is even possible to step outside its structures and demands.

Prospects for neutron star parameter estimation using gravitational waves from f modes associated with magnetar flares

ABSTRACT Magnetar vibrational modes are theorized to be associated with energetic X-ray flares. Regular searches for gravitational waves from these modes have been performed by Advanced LIGO (Laser Interferometer Gravitational-wave Observatory) and Advanced Virgo, with no detections so far. Presently, search results are given in upper limits on the root sum square of the integrated gravitational-wave strain. However, the increased sensitivity of current detectors and the promise of future detectors invite the consideration of more astrophysically motivated methods. We present a framework for augmenting gravitational-wave searches to measure or place direct limits on magnetar astrophysical properties in various search scenarios using a set of phenomenological and analytical models.

A novel electrochemical sensor with NiSx@MoS2 composite for efficient NO2− sensing

Excess nitrites are potentially threatening to human health, so it is urgent to develop accurate and sensitive methods. The development of sensors can provide early warning of possible hazards and alert people to protect public health. This work presents an NiSx@MoS2-composite with excellent electrochemical activity, representing a key finding for highly sensitive NO2− detection and sensor development. With the assistance of NiSx@MoS2, this electrochemical sensor has excellent quantitative detection performance. It has a wide detection range (0.0001–0.0020 mg/mL) and a low detection limit (1.863*10−5 mg/mL) for NO2−. This electrochemical sensor maintains excellent specificity among numerous interferences, and it completes the accurate detection of different real food samples. Pleasingly, the electrochemical sensor has satisfactory repeatability stability, and potential for practical applications. It would demonstrate tremendous potential in scientific dietary guidance, food safety detection and other fields.

Fluorescent probes based on N-CQDs: For direct detection of food additives STPP and Al3+

Sodium tripolyphosphate (STPP), as one of the many food additives, can cause gastrointestinal discomfort and a variety of adverse reactions when ingested by the human body, which is a great potential threat to human health. Therefore, it is necessary to develop a fast, sensitive and simple method to detect STPP in food. In this study, we synthesized a kind of nitrogen-doped carbon quantum dots (N-CQDs), and were surprised to find that the addition of STPP led to the gradual enhancement of the emission peaks of the N-CQDs, with a good linearity in the range of 0.067–1.96 μM and a low detection limit as low as 0.024 μM. Up to now, there is no report on the use of carbon quantum dots for the direct detection of STPP. Meanwhile, we found that the addition of Al3+ effectively bursts the fluorescence intensity of N-CQDs@STPP solution and has a good linear relationship in the range of 0.33–6.25 μM with a lower detection limit of 0.24 μM. To this end, we developed a fluorescent probe to detect STPP and Al3+. In addition, the probe was successfully applied to the detection of bread samples, which has great potential for practical application.

Neuron-astrocyte interaction-inspired percolative networks with metal microdendrites and nanostars for ultrasensitive and transparent electronic skins

Biological systems provide innovative designs for electronic devices, optimizing network configurations for high-performance signal transmission with minimal energy consumption. The brain, as one of the most complex biological structures, demonstrates efficient network design through the multiscale radial networks of neurons and astrocytes. Emulating these brain networks offers a blueprint for the development of ultrasensitive pressure sensors for electronic skin, aiming to provide a more intuitive and sensitive mode of interaction between humans and machines. Herein, we propose a neuromorphic percolative network inspired by neuron-astrocyte interactions for ultrasensitive pressure sensors employing metal microdendrites and nanostars. Electromechanical investigation through representative volume elements simulation reveals that the optimized arrangement of microdendrites and nanostars in the neuromorphic percolative system enhances the percolation threshold and probability. Following these simulation results, we developed a neuromorphic percolative polyurethane (NP-PU) matrix utilizing the metal microdendrite-nanostar networks. The augmented quantum tunneling effect in the NP-PU matrix was investigated through electrochemical impedance spectroscopy and capacitance analysis. The fabricated piezoresistive pressure sensor with the NP-PU matrix shows ultrahigh sensitivity (160.3 kPa−1) at a low pressure range and a low limit of detection resolution (4 Pa), enabled by multi-channel quantum tunneling in the metal particle networks. Furthermore, the sensor maintains excellent mechanical flexibility and high optical transparency (75.4 %), improving its efficacy in applications like electronic skin and force touch panel. Our study highlights the potential of leveraging biological system-inspired network designs for crafting advanced electronic devices.

An integrated adaptive allocation model for unified optimization of conventional and unconventional water resources based on fairness and efficiency

Unconventional water (UW) use has pros and cons, presenting the challenge of matching water utilization with regional water use characteristics. This study proposed the concept of amount-centered adaptive water allocation and built an integrated adaptive allocation model that includes conventional water (CW) and UW adaptability. The model consists of two modules. The first module introduces the regional composite index and inequality index to match CW and UW allocation amount with the sub-region’s characteristics. The second module defines the efficiency of CW and UW allocation, employs the Zero-Sum Gains Data Envelopment Analysis to find the solution set with the highest efficiency on the Pareto front, and further modifies it to reach the optimal allocation efficiency. Then the proposed model was applied to Jiangsu Province, China. Empirical and comparative analyses of the 54 weighting plans proved the validity and practicability of the model. The results showed: (1) The model tallies with the principles of fairness and efficiency and reduces the spatial heterogeneity of water shortage risk; (2) When available water supply decreases by over 20% due to future water-related emergency incidents, CW allocation would first reach its upper limit, while UW fails to effectively bridge the supply–demand gap; (3) Only by improving the maximum UW consumption by over 40% can the future risk of extreme water shortages be effectively addressed. The model proposed in this study has excellent practicality and application potential, providing a novel perspective for incorporating UW into the unified management of water resources.

NiCo layered double hydroxide nanosheet arrays constructed via in-situ plasma etching as non-enzymatic electrochemical sensor for glucose in food

The design and construction of an efficient non-enzymatic glucose electrochemical sensor is of great significance for food quality assessment. Here, we have developed a method to fabricate highly efficient catalytic electrodes for glucose sensing in alkaline. This method utilizes microplasma assistance during the in-situ etching of NiCo layered double hydroxide nanosheet arrays on nickel foam (NiCo-LDH/NF). The NiCo-LDH nanosheets possessed uniform dispersion without agglomeration, high electrochemically active surface area, and excellent electron transfer efficiency (the electron transfer coefficient (α) up to 0.91, the catalytic rate constant (k) was 2.44 × 106 cm3 mol−1 s−1). The NiCo-LDH/NF-based non-enzymatic glucose sensor exhibits the broad linear range (0.4–150 μM), high sensitivity (98000 μA mM−1 cm−2), and the low detection limits (48.76 nM) with satisfactory reproducibility and selectivity. This work developed a simple and rapid in-situ approach for constructing non-enzymatic electrochemical sensors with high sensitivity.

The First Evidence of a Host Star Metallicity Cutoff in the Formation of Super-Earth Planets

Planet formation is expected to be severely limited in disks of low metallicity, owing to both the small solid mass reservoir and the low-opacity accelerating the disk gas dissipation. While previous studies have found a weak correlation between the occurrence rates of small planets (≲4R ⊕) and stellar metallicity, so far no studies have probed below the metallicity limit beyond which planet formation is predicted to be suppressed. Here, we constructed a large catalog of ∼110,000 metal-poor stars observed by the TESS mission with spectroscopically derived metallicities, and systematically probed planet formation within the metal-poor regime ([Fe/H] ≤−0.5) for the first time. Extrapolating known higher-metallicity trends for small, short-period planets predicts the discovery of ∼68 super-Earths around these stars (∼85,000 stars) after accounting for survey completeness; however, we detect none. As a result, we have placed the most stringent upper limit on super-Earth occurrence rates around metal-poor stars (−0.75 < [Fe/H] ≤ −0.5) to date, ≤ 1.67%, a statistically significant (p-value = 0.000685) deviation from the prediction of metallicity trends derived with Kepler and K2. We find a clear host star metallicity cliff for super-Earths that could indicate the threshold below which planets are unable to grow beyond an Earth-mass at short orbital periods. This finding provides a crucial input to planet-formation theories, and has implications for the small planet inventory of the Galaxy and the galactic epoch at which the formation of small planets started.

A dual-channel fluorescent probe targeting lysosomes for differential detection of Cys/Hcy and GSH: Applications in food, pharmaceutical analysis and bioimaging

Thiols function as antioxidants in food, prolonging shelf life and enhancing flavor. Moreover, thiols are vital biomolecules involved in enzyme activity, cellular signal transduction, and protein folding among critical biological processes. In this paper, the fluorescent probe PYL-NBD was designed and synthesized, which utilized the fluorescent molecule pyrazoline, the lysosome-targeted morpholine moiety, and the sensing moiety NBD. Probe PYL-NBD was tailored for the recognition of biothiols through single-wavelength excitation, yielding distinct fluorescence emission signals: blue for Cys, Hcy, and GSH; green for Cys, Hcy. Probe PYL-NBD exhibited rapid reaction kinetics (<10 min), distinct fluorescence response signals, and low detection limits (15.7 nM for Cys, 14.4 nM for Hcy, and 12.6 nM for GSH). Probe PYL-NBD enabled quantitative determination of Cys content in food samples and L-cysteine capsules. Furthermore, probe PYL-NBD had been successfully applied for confocal imaging with dual-channel detection of biothiols in various biological specimens, including HeLa cells, zebrafish, tumor sections, and Arabidopsis thaliana.

A near-infrared ratiometric fluorescent probe for the sensing and imaging of sulfur dioxide derivatives in living systems

As a reactive sulfur species, sulfur dioxide (SO2) and its derivatives play crucial role in various physiological processes, which can maintain redox homeostasis at normal levels and lead to the occurrence of many diseases at abnormal levels. So, the development of a suitable fluorescent probe is a crucial step in advancing our understanding of the role of SO2 derivatives in living organisms. Herein, we developed a near-infrared fluorescent probe (SP) based on the ICT mechanism to monitor SO2 derivatives in living organisms in a ratiometric manner. The probe SP exhibited excellent selectivity, good sensitivity, fast response rate (within 50 s), and low detection limit (1.79 µM). In addition, the cell experiment results suggested that the SP has been successfully employed for the real-time monitoring of endogenous and exogenous SO2 derivatives with negligible cytotoxicity. Moreover, SP was effective in detecting SO2 derivatives in mice.

SWCNT fibers decorated with Au nanoparticles as voltammetric sensors for arsenic (III) determination

We developed a new method to produce fiber electrodes from single-walled carbon nanotube (SWCNT) films, which can be employed as a novel sensing platform for electrochemical investigations and analysis. By assembling SWCNT bundles in the form of a strong free-standing fiber with almost entire surface accessible to an analyte, we are able to avoid the interference of substrate and improve detection efficiency. We examined the influence of physical, chemical and electrochemical pretreatments of the new electrode SWCNT material on its properties. Transmission and scanning electron microscopy, Raman spectroscopy and cyclic voltammetry were used to characterize the SWCNT fibers. The modification of the SWCNT fiber electrode with gold nanoparticles provides the necessary analytical characteristics including high repeatability and sensitivity and low detection limit (1.3 – 2.1 μg L-1) for arsenic determination by anodic stripping voltammetry. Arsenic detection parameters such as deposition potential, deposition time and scan rate were optimized. Linear responses were found in concentration ranges from 3 to 210 μg L-1 and 7 to 125 μg L-1 for gold modified SWCNT fiber sensors (the SWCNTs were synthesized using CO or ethanol as precursors) at a relatively low deposition time of 60 s. The developed Au-SWCNT sensors allow rapid As determination in real samples and exhibit high durability and long service life.

Enhance electrochemical sensing of ascorbic acid and dopamine using V-CuO/GO nanocomposite

The electrochemical detection of Ascorbic acid and dopamine is crucial due to their vital roles in biological processes. Both biomolecules coexist in the human body and have the same oxidation potential, leading to electrode fouling and overlapping of oxidation potential. Accurate detection enables monitoring their levels in biological samples, aiding in disease diagnosis and treatment. This study presents the fast and green synthesis of a highly sensitive and selective electrochemical biosensor for the simultaneous detection of dopamine and ascorbic acid. The change in spherical cluster morphology into nanorods enhances the electrode's electroactive surface area, enhancing sensor sensitivity and selectivity. Electrochemical characterization techniques, including cyclic voltammetry and electrochemical impedance spectroscopy, demonstrated excellent electron transportation and low charge transfer resistance. The sensor exhibited simultaneous detection with a low limit of detection of 8 µM for dopamine and 6.9 µM for ascorbic acid, with a wide linear working range. Additionally, the sensor showed excellent selectivity and repeatability with a vast potential gap at simultaneous detection, making it suitable for clinical and food industry applications.

Monitoring of clinical drug osimertinib based on red phosphorus@silver composite SERS substrate synthesized by a photo-induced in-situ reduction method

Surface enhanced Raman scattering (SERS) with high detection sensitivity has emerged as a fascinating protocol for monitoring trace amount of drugs in clinical serum sample. Herein, a simple and environmentally friendly photo-induced in-situ reduction strategy was proposed to synthesize RP@Ag composites with both SERS and photocatalytic activities. By carefully adjusting the concentration of the Ag source in the precursor solution, the amount and diameter of the decorated Ag nanoparticles were precisely tuned. The resulting optimal RP@Ag composites exhibited reliable SERS enhancement ability (enhancement factor: 1.76 × 107) and the highest degradation efficiency (degradation ratio: 95.04 %, irradiation time: 120 mins) in recyclable detection of Rhodamine B. After further confirming the reliable accuracy, sensitivity, homogeneity, and durability of the RP@Ag composites, they were used to monitor osimertinib and enabled an extremely low limit of detection as 1.63 × 10−7 mg/mL. In particular, such a recyclable SERS platform achieved perfect recovery rates, the obtained deviations were all within 10 % in the monitoring of clinical samples from patients taking medicine for different durations.

Novel phenazine-based microporous organic network for selective and sensitive determination of trace sulfonamides in milk samples

BackgroundSulfonamide (SA) residues in food of animal origin possess a potential threat to human health and environment. However, due to the polar and ionic characteristics and trace level of SAs and the complexity of food matrices, direct measurement of SAs in these samples is still very difficult. Development of efficient sample pretreatment method for sensitive and selective extraction of trace SAs is of great significance and urgently desired. Therefore, rational design and synthesizing advanced and selective extractants is quite important. ResultsIn this work, a novel phenazine-based microporous organic network (MON) named TEPM-DP is reasonably synthesized and employed as a packing material for selective solid phase extraction (SPE) and sensitive determination of four typical SAs in milk samples. Phenazine-based monomer with aromatic and heteroaromatic ring and numerous N atoms is chosen to construct TEPM-DP adsorbent to provide π-π, hydrogen bonding, hydrophobic, and electrostatic extraction sites for SAs. The proposed method owns wide linear ranges, low limits of detection, high enrichment factors, and good precisions and recoveries for SAs in complex milk samples. The recoveries of SAs on TEPM-DP are much higher than those of commercial C18 and activated carbon. The extraction mechanisms are also elucidated via FT-IR, XPS, and comparative experiments. SignificanceThis work reports the first example of design and synthesizing phenazine-based MON in SPE via a simple and rapid solvothermal method. The results reveal the great prospects of TEPM-DP for enriching polar and ionic SAs in complex samples and uncover the potency of phenazine-based MON in sample pretreatment, which will promote the development of MON.

Molecular imprinting electrochemical sensor based on hollow spherical PProDOT-2CH2OH and chitosan-derived carbon materials for highly sensitive detection of chloramphenicol

The misuse of chloramphenicol (CAP) has jeopardized environmental safety. It is critical to create an effective and sensitive CAP detection technique. In this paper, a composite of chitosan (CS)-derived carbon material modified hollow spherical hydroxylated poly(3,4-propylenedioxythiophene) (PProDOT-2CH2OH) was designed, which innovatively used o-phenylenediamine and p-aminobenzoic acid as bi-functional monomers to prepare molecular imprinting polymer (MIP) sensors for highly sensitive analysis and determination of CAP. It was found that the hollow spherical structure of PProDOT-2CH2OH significantly enhanced the rapid electron migration. When combined with the CS-derived carbon material, which has multi-functional sites, it improved the electrical activity and stability of the sensor. It also provided more active centers for the MIP layer to specifically recognize CAP. Therefore, this MIP sensor had a wide linear response (0.0001 ∼ 125 μM), a low limit of detection (LOD, 6.6 pM), excellent selectivity and stability. In addition, studies showed that the sensor has potential practical value. Environmental implicationChloramphenicol (CAP) is one of the most widely used antibiotics with the highest dosage due to its low price and broad-spectrum antimicrobial properties. Due to its incomplete metabolism in living organisms and its difficulty in degrading in the environment, contamination caused by it can pose a threat to public health. In this study, a novel molecularly imprinted sensor (MIP/PC2C1/GCE) was designed to provide a new idea for rapid and precise removal of CAP by adsorption. The detection of CAP in pharmaceutical, water quality, and food fields was realized.

Highly sensitive electrochemiluminescence sensing platform based on copper nanoclusters synthesized via a DNA nanoribbon template for the detection of cancer cells

Herein, we presented a simple ultra-sensitive "on-off-on" electrochemiluminescence (ECL) biosensor that uses copper nanoclusters (CuNCs) synthesized via a DNA nanoribbon (DNR) template (DNR-CuNCs) as a sensing platform coupled with target-cycle amplification for the sensitive and rapid detection of cancer cells that overexpress proteins. DNR templated DNR-CuNCs, a well-ordered ECL emitter, was integrated into the nucleic acid framework structure to self-assembly, which enhanced the ECL intensity benefit from reduced band gap and accelerated electron transfer reaction of CuNCs. Additionally, an optimized exonuclease III (Exo III)-assisted cycle amplification method was introduced to efficiently convert trace target biomarkers into a substantial output of DNA, significantly improving target conversion efficiency and boosting the ECL signal. Consequently, MUC1 proteins were sensitively detected by the ECL biosensor throughout a broad concentration range, from 1 fg·mL−1 to 1 ng·mL−1, with a low limit of detection (LOD) of 0.061 fg·mL−1, and successfully detected MUC1-overexpressing cancer cells (using MCF-7 cancer cells as a model), accurately identifying MCF-7 cells in the concentration range of 10–100,000 cells·mL−1 with a LOD of 5 cells·mL−1. This research, for the first time, introduced a DNR-CuNCs ECL biosensor for the highly sensitive detection of living cells and their associated surface proteins. The detection of biomarker proteins and specific cells is greatly promising by applying this simple, sensitive, and specific strategy.

A glassy carbon electrode modified with gold decorated iron oxide/ carbon dots for light assisted voltammetric detection of antibiotic resistant microbe Enterococcusfaecalis

Detecting bacteria is essential in managing significant health concerns as it enables timely intervention, reducing complications and improving patient outcomes, particularly in treating common infections that necessitate precise identification for effective symptom management. Enterococcus species represent a notable threat in hospital-acquired infections and urinary tract infections (UTIs), given the increasing prevalence of strains resistant to multiple antibiotics, unresponsive to standard therapies, and carrying various virulence factors. Traditional approaches to identifying Enterococcus faecalis (E. faecalis) have limitations, including prolonged processing times, limited sensitivity, and the potential for false positive results. While Polymerase Chain Reaction (PCR) is a valuable tool, it is susceptible to contamination and variations in DNA concentration. The emerging technique of Photoelectrochemical (PEC) holds promise for enhancing E. faecalis detection by leveraging photogenerated electrons and holes. This study introduces a rapid and precise approach utilizing a light-assisted electrochemical biosensor featuring a glassy carbon electrode modified with a nanocomposite of gold-coated iron oxide and carbon dots (Au@Fe3O4/CDs). The nanocomposite was successfully synthesized and underwent thorough characterization. The investigation has a detection range from 1 to 14 CFU mL−1, along with a notably low limit of detection (LOD: 3 CFU mL−1, LOQ: 10 CFU mL−1). Rigorous examination of real-world samples such as food, water, and soil demonstrated exceptional specificity, reproducibility, and long-term stability of the sensor. The applications of the Au@Fe3O4/CDs nanocomposite in PEC processes underscore the potential of this innovative approach in addressing health concerns associated with bacterial infections and delivering real-time impacts for both healthcare and environmental domains.

Highly sensitive colorimetric detection of ascorbic acid using molecularly imprinted photonic crystal hydrogel sensor

Molecular imprinted photonic crystal hydrogel (MICPH) sensors have gained recognition as an efficient platform for selectively detecting analyte molecules. In the present work, we report the development and implementation of a colorimetric sensor based on MIPCH for the selective detection of Ascorbic acid (AA). The fabrication process of the MIPCH sensor involves the photo-polymerization of a hydrogel precursor solution containing AA molecules, which is encapsulated in the interstitial spaces of photonic crystal (PC) opal film. Following the encapsulation, these molecules are selectively removed from the hydrogel network, forming an AA-MIPCH sensor. The sensor exhibits a vivid structural color that redshifts upon rebinding with different concentrations of AA molecules. This alteration in structural coloration serves as a straightforward and visually discernible indicator of the sensor response and enables the quantitative measurement of the target molecule. The sensor exhibits remarkable sensitivity, featuring a low limit of detection (LoD) of 0.011 µM with high selectivity, minimal response time, and promising long-term stability. In addition, the sensor demonstrates its capability to detect the AA even from the complex matrix. A CNN-based deep learning algorithm in MATLAB® was employed to quantitatively predict the concentration of the target molecule. The integration with the machine learning algorithm yields a highly efficient and accurate smart sensor system that is well-suited for real-time sensing of ascorbic acid.