A novel ratiometric BenzoBODIPY-Based fluorescent probe for the detection and imaging of Cysteine in living cells and zebrafish models
Cysteine (Cys) plays a critical role in various biological processes, including protein synthesis, cellular signaling, and antioxidant defense. However, precise detection of Cys in biological systems remains challenging due to interference from similar thiols such as homocysteine (Hcy) and glutathione (GSH). In this study, we report the synthesis and bioimaging of a novel ratio-type fluorescent probe based on the benzoBODIPY fluorophore, designed for the ratiometric detection of Cys. The probe operates through an intramolecular charge transfer (ICT) mechanism, where the reaction with Cys triggers a substitution reaction with 4-mercaptopyridine, followed by a Smiles rearrangement. This results in a shift from red to yellow-green fluorescence, providing a sensitive and specific method for the quantitative detection of Cys. The probe demonstrates excellent selectivity, with significantly lower responses to Hcy and GSH, and has been successfully applied in bioimaging experiments in HeLa cells and zebrafish models, highlighting its potential for diagnosing and treating Cys-related diseases.
Intelligent identification of foodborne pathogenic bacteria by self-transfer deep learning and ensemble prediction based on single-cell Raman spectrum
Foodborne pathogenic infections pose a significant threat to human health. Accurate detection of foodborne diseases is essential in preventing disease transmission. This study proposed an AI model for precisely identifying foodborne pathogenic bacteria based on single-cell Raman spectrum. Self-transfer deep learning and ensemble prediction algorithms had been incorporated into the model framework to improve training efficiency and predictive performance, significantly improving prediction results. Our model can identify simultaneously gram-negative and positive, genus, species of foodborne pathogenic bacteria with an accuracy over 99.99 %, as well as recognized strain with over 99.49 %. At all four classification levels, unprecedented excellent predictive performance had been achieved. This advancement holds practical significance for medical detection and diagnosis of foodborne diseases by reducing false negatives.
Optical-fiber sensor for 17β-Estradiol-binding aptamer evaluation and specific detection of 17β-Estradiol in serum at physiological concentrations
Methods for evaluation of immobilized-small molecule-binding aptamers are rare. In this study, taking the evaluation of 17β-Estradiol (E2) aptamers as an example, we first summarized the reported affinity and specificity results of 16 E2 aptamers, highlighting the issues of insufficient and inconsistent results and the lacking of evaluation of immobilized aptamers. We further exemplified the limited application scope of current affinity techniques by testing the two most widely-applied E2 aptamers, Kim76 and Alsa35, using the three label-free fluorescence assays and two nuclease protection assays. Subsequently, we evaluated the affinity of immobilized-E2 aptamers, Alsa35 and E09, using fiber optic evanescent wave aptasensor (FOEW) based on the competitive binding of target and fluorophore-labeled complementary strand with the fiber surface immobilized-aptamer. The results revealed that Alsa35 had the better affinity and specificity than E09. Using Alsa35-based FOEW, the enzyme-free detection of E2 spiked in river water and human serum was respectively realized with the unprecedented limits of detection (LOD, S/N = 3) of 4.75 (undiluted river water) and 206 pM (undiluted serum). FOEW is a valuable addition to analytical approaches for evaluation of immobilized-aptamers and a general platform for ultrasensitive target detection.
A microfluidic chip incorporating magnetic sorting and invasive separation for isolation, culture and telomerase analysis of circulating tumor cells
Circulating tumor cells (CTCs) are a crucial indicator of cancer metastasis, and are vital for early diagnosis, disease monitoring, and treatment response evaluation. However, their extremely low concentration and the complexities of isolation techniques pose a significant challenge in capturing and analyzing CTCs. In this study, we developed a novel microfluidic system that integrates magnetic capture and invasive screening onto a single microfluidic chip. By attaching positively charged magnetic nanoparticles to negatively charged CTCs, the magnetic separation of CTCs within the chip effectively eliminates interference from blood cells. A total of 2 mL blood sample can be processed within 3 min, achieving an impressive tumor capture efficiency of 84 %. Using the chip, we also successfully achieved long-term culture of CTCs, and identified CTCs with high activity and invasive potential in blood samples from 11 patients with colorectal cancer. Finally, we analyzed telomerase activity in cultured CTCs on the microfluidic chip. Significantly higher invasive potential and telomerase activity were observed in CTCs from the malignant tumor group compared to the benign group (P < 0.01), highlighting their increased aggressiveness. This study offers a novel approach for efficient CTCs isolation, culture, and telomerase analysis, clarifying the crucial role of telomerase in tumor metastasis and providing profound insights for future research on telomerase-targeted tumor metastasis.
A portable, rapid isothermal amplification kit enabling naked eye detection of SARS-CoV-2 RNAs
Since the coronavirus disease 2019 (COVID-19) pandemic, isothermal amplification techniques have attracted attention due to their higher sensitivity and specificity, compared with immunoassays, and their potential application for point-of-care testing (POCT). A requirement of isothermal amplification-based POCT kits is the inclusion of a heating source with an electrical power supply. We developed an amplification-based rapid kit, which is a portable and naked eye-detectable reverse transcriptase (RT)-recombinase polymerase amplification (RPA) kit. The rapid RT-RPA kit consists of a flow-controllable paper chip, a nickel-chromium (NiCr)-based Joule-heating thin film, and a small-sized portable battery. We found that the Joule-heating thin film, powered by a lithium-ion battery (7.5 g, 20 mm × 35 mm size), was able to maintain the required temperature for the RPA reaction. After the RPA reaction, which takes approximately 20 min, the flow-controllable paper chip automatically enabled visualization of the amplicon by time-delayed release of gold nanoparticle-based optical probes. Using this system, we successfully detected severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at levels as low as 10 copies μL, within 30 min.
Hydrogel patch doped with nanoenzyme for SERS detection of hydrogen peroxide in complex body fluids
Abnormally elevated levels of HO in body fluids are strongly correlated with various diseases, particularly cancers. Consequently, there is a significant need to develop a simple and efficient method for direct detection of HO in body fluids. This study presents an economical and feasible hydrogel patch doped with nanoenzyme, specifically gold nanoparticles assembled on the surface of magnetic nanoparticles (Au@FeO NPs), as a sensing platform for HO in complex body fluids. The hydrogel surface-enhanced Raman spectroscopy (SERS) patch demonstrates ultra-high sensitivity for HO in vitro with a detection limit of 10 nM, which is attributed to the excellent catalytic efficiency of Au@FeO NPs and the rich distribution of SERS "hot spots" on the nanoenzyme. Notably, the hydrogel SERS patch exhibits superior specificity, repeatability, and background-free detection of HO in complex body fluids without pre-treatment. Importantly, the HO levels within cancerous cells were observed to gradually increase during the cell death process, as measured using the hydrogel SERS patch developed for practical application. This SERS patch provides a promising, cost-effective strategy for HO detection in complex samples such as body fluids, food, and environmental samples in future applications.
A new sample preparation approach based on microwave-induced combustion in disposable vessels for Ni and V determination by ICP-MS in crude oil
The presence of Ni and V in crude oil is associated with pollutant emissions, corrosive processes and low-quality products. Nevertheless, the knowledge of the concentration of these elements, helps to predict geochemical characteristics and to bring information about the crude oil source. Moreover, Ni and V can cause problems during the crude oil refining process. Therefore, the development of alternative, low-cost and rapid approaches for Ni and V determination in crude oil is still welcomed and was the aim of this work. The proposed microwave-induced combustion in disposable vessels (MIC-DV) system allows the use cheap and/or reusable materials, combined to the possibility of sample combustion under atmospheric pressure and using a domestic microwave. The parameters evaluated during MIC-DV optimization were, sample mass (5-20 mg), and volume (1-10 mL) and concentration (0.5-7 mol L HNO) of absorbing solution. MIC-DV was applied for the digestion of ten crude oil and the results were compared with those obtained after microwave-assisted digestion (MAD) and Ni and V determination by inductively couple plasma mass spectrometry (ICP-MS). The agreement values achieved ranged from 92 to 103 % for Ni and from 93 to 106 % for V. The limits of quantification after MIC-DV/ICP-MS were 0.28 and 0.15 μg g for Ni and V, respectively. The developed MIC-DV method, can be considered environmentally friendly since it uses low-cost materials and instrumentation, requires reduced handling (based on the single vessel principle), avoids the use of additional dilution steps and minimizes the digest contamination.
A new conjugated mesoporous polymer as fluorescence sensor for the detection of nerve agent simulant dimethyl chlorophosphonate via specific nucleophilic substitution reaction
Conjugated micro/mesoporous polymers (CMPs) represent a category of porous organic materials formed via covalent bonds. Here, DAC-TFP CMP was synthesized using 3,6-diaminocarbazole (DAC) and 2-hydroxy-1,3,5-benzenetricarbaldehyde (TFP) as building blocks. DAC-TFP CMP is a porous conjugation polymer with remarkable thermal and chemical stability. DAC-TFP CMP suspension demonstrates selective "on-off" fluorescence response towards nerve agent simulant dimethyl chlorophosphonate (DMCP) in 1,4-dioxane with exceptionally low detection limits. DMCP and DAC-TFP CMP undergo a nucleophilic substitution reaction, leading to the formation of an N-P bond between N atom on carbazole of DAC-TFP CMP and P atom of DMCP. The new polymer DAC-TFP CMP@DMCP has electron donor-acceptor structure and the fluorescence quenching can be ascribed to the intramolecular charge transfer (ICT) from DAC-TFP CMP unit to DMCP group, as supported by XPS results and DFT calculation. Upon the addition of DMCP to the 1,4-dioxane suspension of DAC-TFP CMP, a subtle blue shift is observed in both the fluorescence emission spectra and UV-vis absorption spectra, providing further validation of the ICT mechanism. DAC-TFP CMP shows excellent recoveries in detecting DMCP in both soil and pesticide samples containing mesotrione and atrazine, highlighting its strong potential as a reliable chemosensor for DMCP detection and analysis.
Graphyne-supported manganese single-atom nanozyme sensor array for bisphenol identification
Bisphenols, as common industrial raw materials, are widely used in food packaging such as plastics. However, their migration and residue may affect the hormone secretion of the human body and then lead to health problems. Therefore, a low-cost, rapid and simple detection method that can simultaneously detect multiple bisphenols is very necessary. In this work, two types of manganese single-atom nanozymes with excellent peroxidase-like activity were synthesized with graphyne as a support. A high-throughput colorimetric sensor array was constructed using three types of nanozymes (Mn-GY, Mn-GY-2N, GY-2N) to distinguish various bisphenols. Due to the absorption of bisphenol molecules on the surface of nanozymes, the activity of nanozymes decreases differently, when different bisphenols are added to the catalytic system. The results proved that the prepared sensor had good linear relationships at both low and high concentrations for determination of five bisphenols. The LODs of BPA, BPS, BPF, BPAF, and Diphenolic Acid were 0.443, 0.280, 0.277, 0.424, and 0.326 μM respectively. Compared with traditional sensors, the sensor array can simultaneously detect multiple analytes with high throughput, showing great advantage in dealing with complex samples. Combined with machine learning algorithms, five bisphenols can be successfully identified by the obtained array data. The sensor array also demonstrated excellent performance in the detection of both mixed samples and real samples. This high-throughput colorimetric sensor array achieves accurate and sensitive detection of bisphenol substances, providing new means and ideas for enhancing food safety. At the same time, the simple and rapid identification of structurally similar compounds demonstrates its potential for more precise analysis, providing possibilities for future development.
Oxidative polyacrylonitrile nanofiber-based solid-phase microextraction coatings via wrapping strategy for polychlorinated biphenyls determination coupled to GC-MS
A straightforward approach to fabricating robust and versatile solid-phase microextraction (SPME) fibers is crucial for the extensive research and application of this notable sample preparation technique. Herein, we proposed a strategy for preparation of oxidative polyacrylonitrile (O-PAN) and O-PAN/ZIF-67 nanofiber-based SPME coatings by wrapping an electrospinning membrane on the stainless-steel wire, following with thermal oxidation at 300 °C. The shrinkage of membrane during thermal treatment resulted in the nanofibers being securely affixed to the stainless-steel wire, thereby creating a robust nanofiber-based SPME fiber. Furthermore, the characterizations results indicated that the thermal oxidation significantly enhanced the generation of oxygen-/nitrogen-containing groups within the nanofibers, which were conducive to the adsorption for the analytes. Given the exceptional properties, the proposed O-PAN/ZIF-67 coating was applied to extract and analyze polychlorinated biphenyls (PCBs) pollutants coupled with GC-MS, and exhibited superior extraction performances. The proposed analytical method presented a wide linear range spanning concentrations from 0.5 to 2500 ng L, with a low detection limit ranging between 0.029 and 0.093 ng L. Additionally, it demonstrated good precision, as evidenced by a relative standard deviation of 4.5 %-8.1 %, and was effectively utilized for the analysis of real water samples. This study introduced a novel, simple, and versatile methodology for the fabrication of nanofiber-based SPME coatings, offering a significant advancement in the field.
Highly sensitive ratiometric fluorescence detection of dibutyl phthalate in liquor and water using bio-based fluorescent molecularly imprinted polymers
A novel fluorescent molecularly imprinted polymer (DBP-FMIPs) was designed and prepared for the selective detection of dibutyl phthalate (DBP) in food samples. This was achieved using inclusion complexes formed between short amylose and DBP as precursors, with tetrafluoroterephthalonitrile, which possesses an electron-donor-acceptor type dipolar structure within a compact benzene backbone, serving as a crosslinking agent and fluorescent readout signal. DBP-FMIPs exhibit excellent fluorescence stability and high selectivity, with a response time of less than 3 min for DBP. Based on the blue-green fluorescence emitted by DBP-FMIPs (λ = 500 nm), this material provided the response signal, while the red-emitting carbon dots(R-CDs, λ = 680 nm) were used as an internal reference, constructing a ratiometric fluorescence probe (R-CDs/DBP-FMIPs). The fluorescence intensity ratio (I/I)/(I/I) exhibited a linear response to DBP within a concentration range of 0.020-20 mg L, with a detection limit as low as 4.5 μg L, and its fluorescence color shifted from blue to red. The fluorescent probe was successfully applied for detecting DBP in liquor and drinking water samples, achieving recoveries of 88-107 % and a relative standard deviation of 1.1-6.4 %. This preparation method can also be adapted for synthesizing FMIPs targeting other hydrophobic compounds. Additionally, the developed ratiometric fluorescence probe shows great potential for the selective and visual detection of phthalates in complex samples.
Ag-coated Au nanostar-based Lateral Flow Immunoassay for Highly Sensitive Influenza A virus antibody Detection in Colorimetric and Surface-Enhanced Raman Scattering (SERS) modes
Antibody testing for virus aids diagnosis, promotes vaccination and development, and evaluates antibody treatment efficacy. Hence, it is essential to examine and monitor antibody levels for accurate disease diagnosis and prevention. Lateral Flow Immunoassay (LFIA) is a technique that is known for its simplicity and speed, making it a popular choice for immediate detection. Noble metal nanoparticles are extensively employed in LFIA due to their exceptional colorimetric and Raman properties, which are a result of the LSPR effect. Au nanostars (Au NSs) have excellent SERS properties due to multiple sharp branches and more "hot spots" on the surface, while Ag nanoparticles (Ag NPs) have higher extinction coefficient and better refractive index sensitivity. The electromagnetic field strength on the surface of Ag-Au bimetallic nanomaterial is greatly enhanced, which further enhances the SERS intensity. In this work, we created a core-shell nanoparticle by combining Au NS as the core and Ag as the shell (Au NS@Ag). We then inserted a Raman reporter molecule between the core and shell. Using this, we developed an LFIA platform that can detect influenza A virus antibodies in both colorimetric and Raman modes. The detection limit in colorimetric mode was 0.1 ng/mL, while in Raman mode it was 8.0 pg/mL, making it approximately 12 times more sensitive than the colorimetric mode. Furthermore, the method has shown excellent specificity, stability, and resistance to interference. Hence, this method can be applied to various fields such as environmental monitoring, clinical diagnosis, and food safety, showing great potential for future applications.
Selective detection of Fe via fluorescent in real sample using aminoanthraquinone resorcin[4]arene-based receptors with logic gate application
Resorcin[4]arene based fluorescent sensors RES-AAQ containing eight anthraquinone groups as binding sites, were developed for very accurate and sensitive detection of Fe metal ion. The motivation for this study lies in the need for advanced sensing techniques for precisely identifying Fe ions. Due to its unique redox properties, Fe plays a crucial role in biological processes, environmental remediation, medical diagnostics, and advanced detection methods. The sensors were extensively characterized using FT-IR, H NMR, C NMR, and ESI-MS techniques. The absorption spectra revealed significant interactions between RES-AAQ and Fe ions. Fluorescence quenching was observed due to Photoinduced electron transfer (PET). The quenching process was systematically analyzed using Stern-Volmer analysis. Each sensor (L, L, L, L) demonstrated remarkable detection limits for Fe ions (10.51 nM, 10.48 nM, 10.49 nM, 10.47 nM, respectively) along with substantial binding affinities (binding constants: 9.07x10 M, 1.19x10 M, 1.49x10 M and 1.03x10 M for L, L, L, and L, respectively). Traditional, Fe detection methods often suffer from limitations such as complexity, lack of sensitivity, or interference from other metal ions. This research offers highly sensitive fluorescent sensors for Fe detection with potential applications in human blood serum and tap water. Molecular docking, DFT studies, and ESI-MS investigation have been employed to gain insights into the binding interactions between the molecules. The low detection limits, high binding affinity, and real-world applicability highlight the significant advantages of developed sensors compared to existing methods. Additionally, a combinatorial logic gate was constructed to facilitate a proper understanding of the working principle of RES-AAQ.
Target-driven functionalized DNA hydrogel capillary sensor for SARS-CoV-2 dual-mode detection
Coronavirus disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused secondary pandemic, which still poses a serious threat to physical health and economic development. Herein, the target-driven functionalized DNA hydrogel capillary sensor based on cascade signal amplification and carbon coated cobalt manganese modified by prussian blue and platinum nanoparticles (MnCo@C-Pt-PB NPs) has been successfully developed for dual-mode detection of SARS-CoV-2. The cascade signal amplification triggered by target RNA causes the permeability of the DNA hydrogel loaded in the capillary to be destroyed, thereby releasing the embedded MnCo@C-Pt-PB NPs as signal molecules into 3,3',5,5'-tetramethylbenzidine/hydrogen peroxide (TMB/HO) solution under the driving of capillarity. The colorless TMB is then catalyzed to blue oxidation products (oxTMB) due to peroxidase-like activity of MnCo@C-Pt-PB NPs, and MnCo@C-Pt-PB NPs and oxTMB with photothermal properties synergistically increase the system temperature under near-infrared irradiation, which are recorded by portable devices to achieve dual-mode detection. Signals intensity are proportional to the logarithm of T-RNA concentration in a wide detection range (100 aM-100 pM), with a detection limit of 100 aM. Moreover, the reliability of the developed method in oropharyngeal swabs samples has also been validated. The signal conversion and amplification function of functionalized DNA hydrogel enhances the convenience, sensitivity and versatility of the developed method, which is promising to be applied in environmental safety, molecular diagnostic assays and disease prevention.
The electroreduction-free stripping analysis of copper (II) ions and the voltammetric detection of nonylphenol and tetracycline based on graphdiyne/carbon nanotubes
The heavy metal ions (HMI) and π-electronical pollutants are two main types of environmental water contaminants, thus designing a universal sensor for their detection is considerable important. Meanwhile, graphdiyne (GDY) as a star material exhibits many unique advantages, especially superior adsorption and self-reducing property to HMI as well as great affinity to π-electron targets. Herein, by low-cost utilizing carbon nanotubes (CNTs) as the template dedicated to improve the conductivity and dispersibility of GDY, a multifunctional nanohybrid GDY/CNTs was prepared and then revealed successfully as a universal electrochemical sensing material for the HMI and π-electronical pollutants by adopting three models: (a) based on the in-situ adsorption and self-reduction capabilities of GDY towards HMI, an innovative electroreduction-free stripping voltammetry (FSV) sensing strategy was proposed for HMI detection via adopting Cu as a representative, which can effectively avoid the electroreduction process compared with the common anodic stripping voltammetry method; (b) by selecting nonylphenol (NP) and tetracycline (TC) as two representative targets, the sensing performances of GDY/CNTs for the π-electronical pollutants were also confirmed. After optimizing the related experimental parameters, the as-prepared GDY/CNTs exhibits superior analytical performances (the obtained detection limits for Cu, NP and TC are respectively 1.6 nM, 6.67 nM and 1.67 nM coupled with the linearities of 0.005-10.0 μM, 0.02-25.0 μM and 0.005-6.0 μM) owing to the synergistic advantages of GDY and CNTs. This work revealed the as-prepared GDY/CNTs nanohybrids can be utilized as a robust universal sensing material for HMI and pollutants consisting of π-electrons, and especially the proposed FSV sensing strategy is very promising, exhibiting great potential applications.
Tris(2,2'-bipyridine)ruthenium(II)-silver nanoparticle electrostatic nanoaggregates (AgNPs@[Ru(bpy)] ENAs) as novel SERS nanotags for rapid, sensitive and selective immunosensing
Tris(2,2'-bipyridine)ruthenium(II) ([Ru(bpy)]), as a versatile molecule, has been widely applied in various fields, such as photocatalysis, electrochemiluminescence and fluorescence probes, solar cell and LED due to its excellent optical and electrical properties, good water solubility, high chemical stability. In this work, we prepared electrostatic nanoaggregates from [Ru(bpy)] and silver nanoparticles (AgNPs@[Ru(bpy)] ENAs) as a new type of SERS nanotags. Each [Ru(bpy)] ion carries two positive charges with strong affinity to negative surfaces, which enables a strong electrostatic interaction between [Ru(bpy)] and negatively charged silver nanoparticles (AgNPs) and fast (within 10 min) formation of AgNPs@[Ru(bpy)] ENAs. The prepared AgNPs@[Ru(bpy)] ENAs had a very strong and stable SERS activity due to abundant bipyridine molecules in [Ru(bpy)] and the location of many [Ru(bpy)] SERS reporters at the electromagnetic "hot spots" (i.e. the junction of two adjacent AgNPs), and thus could act as novel and excellent SERS nanotags. Further conjugated with antibodies, AgNPs@[Ru(bpy)] nanotags were used to develop new SERS-based immunochromatography test strips (SERS-ICTSs), showing excellent sensing performances. The AgNPs@[Ru(bpy)] ENAs based SERS-ICTSs not only inherit the merit of fast and visualize quantitative analysis from traditional ICTSs, but also realize much more sensitive biosensing (with detection limit of 25 pg/mL HCG) using the SERS technology.
One stone two birds: NH-UiO-66@MB-based bimodal aptasensor for sensitive and rapid detection of zearalenone in cereal products
Zearalenone (ZEN), a prevalent mycotoxin found in cereal crops, poses a significant threat to food safety and human health. To address this issue, there is an urgent need for rapid, sensitive, and cost-effective detection methods. In this study, we developed a novel bimodal aptasensor based on NH-UiO-66@MB composites for ZEN detection. Methylene blue (MB) was encapsulated within NH-UiO-66 nanoparticles to enhance fluorescence intensity, and the ZEN aptamer was attached to NH-UiO-66 via Zr-O-P bonds and Coulombic forces to create a gating effect. In the presence of ZEN, the aptamer bounded to ZEN, triggering a conformational change that released MB, resulting in decreased fluorescence intensity and absorbance. Under optimal conditions, the bimodal aptasensor exhibited wide linear ranges (2.5-300 ng/mL for colorimetry and 0.125-200 ng/mL for fluorescence) and low limits of detection (1.16 ng/mL for colorimetry and 0.03 ng/mL for fluorescence). Furthermore, the aptasensor demonstrated high specificity and reproducibility, with recovery rates ranging from 97.43 % to 103.71 % in spiked cereal products. These findings highlight the potential of the developed bimodal aptasensor as a novel tool for the rapid, accurate, and cost-effective detection of ZEN in cereal products, contributing to improved food safety monitoring.
Bimetallic sulfides based hybrid anodes are constructed for high-performance lithium ion batteries
Transition metal sulfides (TMSs) are considered as one of the most promising anode materials for lithium-ion batteries (LIBs) in virtue of their high theoretical specific capacity, low cost and environmental friendliness. However, the intrinsic poor electron/ion transport, large volume change and the shuttle effect of polysulfides hinder their achievement of superb rate capability and cycle performance. Compared with the monometallic sulfides, bimetallic sulfides have superior electron transport capability and higher electrochemical activity. In this work, bimetallic CuCoS nanomaterial is in-situ synthesized on copper foam (CF) substrate by a facile hydrothermal method. Benefiting from the introduction of heteroatoms and the construction of integrated hybrid structure, the bimetallic CuCoS/CF anode delivers a high specific capacity of ∼1707 mAh g at 0.1 C and maintains ∼84 % of the initial capacity after 1000 cycles at 1.6 C (1 C = 1 A g). This work provides a strategy to utilize bimetallic sulfides as well as construct hybrid electrode of sulfides and conductive metallic frameworks.
Optical detection based spot test on electrospun nanofibers for glioblastoma cells
Paper-based diagnosis is enabled to be used in many applications in global health due to its low cost and simplicity of operation. Electrospun nanofibers (ESNFs) are useful platforms to prepare paper-based diagnostics. Herein, bead-free ESNFs were formed by electrospinning using polystyrene (PS) and poly (ethylene glycol) (PEG) polymers as a paper-based substrate. PS:PEG ESNFs were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), identification of swelling behavior, and Brunauer-Emmett-Teller (BET) analysis. Synthesized gold nanoparticles (AuNPs) were used as a colorimetric probe and GMT8 aptamer was conjugated on the surface of AuNPs. AuNP and AuNP-GMT8 were characterized by dynamic light scattering (DLS), UV-Visible spectrometry, and X-Ray photoelectron spectroscopy (XPS). The interaction of AuNP-GMT8 bioconjugates with glioblastoma cells was examined. The colored spots for the mixture of glioblastoma (U87-MG) cells and AuNP-GMT8 were optically monitored both in the microplate wells and on the PS:PEG ESNFs. The linear range of colorimetric analysis on PS:PEG ESNFs was determined to be between 10-10 U87-MG cells/mL by smartphone using RGB color analysis.
Efficient Cd separation protocols for high-precision cadmium isotope analyses of diverse samples by double spike MC-ICP-MS
Cadmium isotope analyses are applied for research in planetary, Earth, environmental and life sciences. However, there is still a lack of efficient methods for the separation of the trace element Cd from the different types of samples that are of interest for isotopic analyses. This study presents new and improved Cd separation and purification techniques for meteorite, diverse terrestrial and seawater samples prior to Cd isotope measurements by multiple collector ICP-MS using the double spike approach for mass bias correction. The first separation stage for meteorites and terrestrial samples employs an existing anion exchange chromatography method that uses AG MP-1M resin, whilst AG 1-X8 and Nobias Chelate PA-1 resins were applied for the initial isolation of Cd from small and large seawater samples, respectively. Teflon microcolumns and AG MP-1M anion exchange resin was then employed for further Cd purification of all sample types. The methods consistently isolate Cd from matrix elements more efficiently than previous protocols, whilst achieving consistently high Cd recoveries, of >95 % for meteorite and terrestrial samples and >80 % for seawater samples, combined with low procedural blanks of <0.08 ng. The performance of the new protocols is demonstrated by repeated Cd isotope analyses of well-characterized geological and biological reference materials, which produced data that are in excellent agreement with results that were obtained with previous, more laborious separation methods. Furthermore, precise Cd isotope compositions (δCd) are presented for the Murchison meteorite and, for the first time, the ordinary chondrite GRO 95504. Finally, analyses of seven seawater samples, with Cd concentrations between 0.25 and 0.91 nmol kg using sample volumes of up to 2 L, generated results consistent with those of previous studies. Overall, the new methods thus enable unbiased δCd measurements for diverse sample types with a 2SD precision of better than ±0.07 ‰, even for samples with 10 ng or less of natural Cd.
Calibration-free disposable electrochemical sensor with co-facing electrodes for viscosity monitoring of plasma samples
Plasma viscosity measurement is crucial in clinical diagnostics, providing insights into blood rheology and health status. Traditional methods, such as capillary and rotational viscometers, require large sample volumes and complex calibration. This study presents a novel disposable electrochemical sensor with co-facing electrodes for viscosity monitoring of plasma samples. The sensor independently determines the diffusion coefficient (D) of the electroactive test molecule ferrocyanide, eliminating the need for calibration curves. This enables the subsequent calculation of the solution's viscosity via the Stokes-Einstein relation. The sensor's performance was validated against a standard quartz-crystal microbalance method, demonstrating high accuracy and reliability. It maintained consistent measurements despite the presence of common electroactive plasma interferents such as ascorbic acid (≤160 μM), dopamine (<9.0 nM), uric acid (<1.0 mM), and urea (<15.6 mM). Although these interferents impacted D at concentrations exceeding twice the maximum levels typically present in plasma, the sensor exhibited robust performance under normal physiological conditions and standard interferent concentrations. The sensor offers rapid response times of less than 20 s, requires only 7 μL of sample, and is cost-effective, making it suitable for point-of-care applications. Bland-Altman plot analysis confirmed its precision, showing a mean difference of 0.00877 and narrow limits of agreement compared to the standard method used.