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Neuroblastoma (NB) is a significant pediatric cancer associated with high mortality rates, demanding innovative and appropriate approaches for its accurate detection. This paper described the design of a dual-target electrochemical aptasensor capable of simultaneously detecting neuroblastoma-associated microRNAs (miRNA-181 and miRNA-184) with exceptional sensitivity. Screen-printed carbon electrodes (SPCEs) were utilized with gold nanorods (AuNRs), and aptamers functionalized gold nanoparticles (AuNPs) to improve sensitivity, specificity, and portable detection ability. The detection method employed in this study includes differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Our aptasensor exhibited remarkable limits of detections (LODs) of 5.10 aM for miRNA-181 and 9.39 aM for miRNA-184, respectively, along with a broad linear range spanning from 0.1 fM to 100 pM for both miRNAs. The practical significance of neuroblastoma diagnosis was shown through the validation of serum samples and comparison with quantitative polymerase chain reaction (qPCR). Our electrochemical aptasensor is user-friendly, easy to engineer, and offers a promising approach for accurately and selectively detecting important miRNA biomarkers in cancer screening and diagnosis, showing potential application in various clinical scenarios.

In this study, we present the development of an innovative electrochemical biosensor integrated into a microneedle-based system for non-invasive and sensitive quantification of cholesterol levels in interstitial fluid (ISF). The biosensor employs a graphene-based electrode with a polyelectrolyte interlayer to immobilize cholesterol oxidase (ChOx), enabling selective cholesterol detection. Graphene oxide is electrochemically reduced to form a conductive layer, and PANI is chosen as the optimal polyelectrolyte for ChOx immobilization. The biosensor's performance is thoroughly evaluated, demonstrating excellent sensitivity, stability, and selectivity. Furthermore, the biosensor is successfully applied to skin-mimicking agarose gel and porcine skin, showcasing its potential for real-world interstitial fluid extraction and cholesterol monitoring. The integrated microneedle-based system offers a promising approach for non-invasive monitoring of cholesterol levels, with implications for personalized healthcare diagnostics.

Norfloxacin (NOR) and levofloxacin (LEV) are the two most frequently used fluoroquinolones (FQs) in clinic. Their residues seriously endanger the ecosystem and human health. Due to their similarity in structure and properties, it is urgent to develop an efficient and sensitive strategy for detection and differentiation. Herein, we synthesized a novel ratiometric fluorescent sensor for the first time by combining N, S co-doped carbon dots (CDs) and the precursors of Tb-MOFs through a facile one-pot method. The introduction of CDs effectively facilitated the energy transfer between Tb³⁺ and FQs, overcoming the limitation that single Tb-MOFs could not identify similar antibiotics. Specifically, the presence of NOR resulted in reverse signal response through the inner filter effect and antenna effect. The synergistic effect of these two mechanisms contributed to achieving signal amplification accompanied by a distinguishable color transition. The limit of detection (LOD) was 0.036 μM. Different from NOR, the addition of LEV reduced the electron density of the system, weakened the coordination ability of Tb³⁺ with LEV, and induced a single signal response with Tb³⁺ fluorescence intensity as a reference signal (LOD = 0.383 μM). Furthermore, the method proved to be rapid and visual, allowing for the straightforward analysis of FQs residues in water, food matrices, and biological samples with satisfactory precision. By integrating N, S-CDs@Tb-MOFs with flexible substrates, the paper-based sensor facilitated the visual quantitative determination of FQs by reading RGB values. The developed sensor presents a promising strategy for the identification and real-time monitoring of antibiotics.

The traditional external standard calibration method (EC) is automated and simplified using a four-port switching valve (SV4) and a multi-signal approach that enables the generation of several calibration points from a single calibration solution. The SV4-EC method is applied to inductively coupled plasma optical emission spectrometry (ICP-OES) and is based on gradient dilution taking place within the instrument's sample introduction tubing. Both the calibration solution and the samples are diluted by a blank solution containing an internal standard species. Forty-five dilution points are collected over time while the solutions are mixed. Instrument responses from the calibration solution are then plotted against those from the samples, and the slope of the calibration curve is used to determine the unknown analyte concentrations in the samples. The method is used to determine Ba, Co, Cr, Cu, Fe, Mn, Ni, V and Zn in coconut water, creek water, green tea, mouthwash, soft drink, vinegar, and vodka. Limits of detection are in the 0.0002–0.009 mg L⁻¹ (n = 10) range, with precision on the order of 0.4 %–3 % RSD. Analyte percent recoveries from a 0.5 mg L⁻¹ spike are in the ranges of 88.4 %–111 %, 88.9 %–111 %, and 88.0 %–111 % for EC, SV4-EC, and the internal-standard-corrected method (SV4-EC/Sc), respectively. No statistically significant difference is observed between EC and SV4-EC recoveries for any of the sample matrices evaluated. Comparable results between EC and SV4-EC were also found for the analysis of two certified reference materials, Bovine Liver and Oyster Tissue. Based on a single calibration solution, the SV4-EC method requires caution when preparing the calibration standard to minimize measurement bias.

Tumor cell-derived extracellular vesicles (TEVs) contain numerous cellular molecules and are considered potential biomarkers for non-invasive liquid biopsy. However, due to the low abundance of TEVs secreted by tumor cells and their phenotypic heterogeneity, there is a lack of sensitive and specific methods to quantify TEVs. Here, we developed a dual-aptamer proximity ligation-coupled hybridization chain reaction (HCR) method for tracing TEVs, exploiting CRISPR to achieve highly sensitive detection. Taking advantage of the high binding affinity of aptamers, the two aptamers (Apt_EpCAM, Apt_HER2) exhibited the high selectivity for TEVs recognition. HCR generated long-repeated sequence containing multiple crRNA targetable barcodes, and the signals were further amplified by CRISPR upon recognizing the HCR sequences, thereby enhancing the sensitivity. Under optimal conditions, the developed method demonstrated a favorable linear relationship in the range of 2 × 10³−10⁷ particles/μL, with a limit of detection (LOD) of 3.3 × 10² particles/μL. We directly applied our assay to clinical plasma analysis, achieving 100 % accuracy in cancer diagnosis, thus demonstrating the potential clinical applications of TEVs. Due to its simplicity and rapidity, excellent sensitivity and specificity, this method has broad applications in clinical medicine.

In this work, electromembrane extraction (EME) was used for the first time to separate aconitine (AC), mesaconitine (Mes-AC) and hypaconitine (Hyp-AC) from biological samples and Chinese herbal medicines. Efficient EME of polar and high molecular weight aconitine alkaloids from different sample matrices was achieved with the solvent of 1-ethyl-2-nitrobenzene (ENB). Under the optimal EME conditions, EME provided recoveries for all targets in the range of 72%–74 %, 85%–103 % and 92%–94 % for whole blood, urine and aqueous samples. The proposed EME systems combined with LC-MS/MS and HPLC-UV were evaluated using different sample matrices, and the methods displayed satisfactory analytical characteristic including negligible matrix effect. The LOD and LOQ of AC, Mes-AC, and Hyp-AC by EME-LC-MS/MS were in the range of 0.002–0.068 ng/mL and 0.005–0.228 ng/mL respectively. The LOD and LOQ of AC, Mes-AC, and Hyp-AC by EME-HPLC-UV were in the range of 0.06–0.26 μg/mL and 0.20–0.86 μg/mL, respectively. The coefficient of determination, R²-value was ≥0.9926 for all cases, and the accuracy in the linear ranges was in the range of 91%–111 %. Finally, the method was successfully applied for the qualitative and quantitative analysis of AC and Mes-AC in the whole blood and herbal medicine dreg samples from an actual forensic case, and poisoning by aconitum alkaloids was identified as the cause of death. Therefore, we believe that EME could be a powerful tool to identify poisoning, and EME has great potential for efficient separation of polar and high molecular weight substances. These are of great importance in the fields of but not limited to forensic science, Traditional Chinese Medicine and clinics.

Molecularly imprinted polymers (MIPs) have been widely used as artificial recognition elements in sensing applications. However, their electrochemical sensing performance is generally hampered by limited affinity and uncontrolled condition change. In this work, a novel MIP electrochemical sensor based on metal coordination interaction was prepared and used for the recognition and ratiometric detection of lidocaine (LC). The sensor was constructed by electrodepositing Cu-coordinated MIP on biomass carbon modified glassy carbon electrode. Herein, Cu²⁺ ions acted as anchor for the immobilization of LC during the synthesis process, enabling the orderly formation of molecular recognition sites. Reversely, the metal coordination between Cu²⁺ ions and LC molecules facilitated the recognition of LC. Moreover, the doped cupric ions in the polymer film could provide a reference signal for subsequent ratiometric strategy. Thus the resulting sensor exhibited high selectivity, sensitivity, satisfactory reproducibility, and anti-interference ability. Under the selected conditions, the peak current ratio of LC and cupric ion was linear to LC concentration in the range of 0.008–2.5 μmol L⁻¹ (R² = 0.9951), and the limit of detection was 1.9 nmol L⁻¹ (S/N = 3). The practical feasibility of the sensor was evaluated by detecting human serum and pharmaceutical samples, and satisfactory outcomes were obtained.

The discovery of pancreatic lipase (PL) inhibitors is an essential route to develop new anti-obesity drugs. In this experiment, chitosan was used to add amino groups to cellulose filter paper (CFP) and then glutaraldehyde was used to covalently combine PL with amino-modified CFP through the Schiff base reaction. Under optimal immobilization conditions, CFP immobilized PL has a wide range of pH and temperature tolerance, as well as excellent reproducibility, reusability and storage stability. Subsequently, 26 natural products (NPs) were screened by immobilized PL with black tea extract having the highest inhibition rate. Three compounds with binding effects on PL (epigallocatechin gallate, theaflavin-3-gallate and theaflavin-3,3′-digallate) were captured. Molecular docking proved that these three compounds have a strong binding affinity for PL. Fluorescence spectra further revealed that theaflavin-3,3′-digallate could statically quench the intrinsic fluorescence of pancreatic lipase. The molecular docking and thermodynamic parameters indicated that electrostatic interaction was considered as the main interaction force between PL and theaflavin-3,3′-digallate. Finally, the potential anti-obesity targets and pathways of the three compounds were discussed through network pharmacology. This study not only proposes a simple and efficient method for screening PL inhibitors, but also sheds light on the anti-obesity mechanism of active compounds in black tea.

Hypochlorous acid (HClO) serves as a critical biomarker in inflammatory diseases such as rheumatoid arthritis (RA), and its real-time imaging is essential for understanding its biological functions. In this study, we designed and synthesized a novel probe, RHMB, which ingeniously integrates rhodamine B and methylene blue fluorophores with HClO-specific responsive moieties into a single molecular framework. Upon exposure to HClO, RHMB exhibited significant dual-channel fluorescence enhancement characterized by high sensitivity (LODs of 2.55 nM and 14.08 nM), excellent selectivity, and rapid response time (within 5 s). Notably, RHMB enabled reliable imaging of both exogenous and endogenous HClO in living cells and in zebrafish, employing a unique duplex-imaging turn-on approach that highlighted its adaptability across various biological contexts. Furthermore, RHMB effectively monitored HClO fluctuations in an RA mouse model and assessed the therapeutic efficacy of diclofenac (Dic) in alleviating RA symptoms. These findings underscore the potential of RHMB as an invaluable tool for elucidating the biological roles of HClO in various diseases.