A low-field nuclear magnetic resonance DNA-hydrogel nanoprobe for bisphenol A determination in drinking water

Multiplex aptamer cluster detection platform and systems toxicology study for 17β-estradiol, bisphenol A, and diethylstilbestrol

Intake of 17β-estradiol (E2), bisphenol A (BPA), and diethylstilbestrol (DES) from food can contribute to endocrine disorders. Therefore, developing a sensitive method for the simultaneous detection of E2, BPA, and DES and understanding their combined effects on endocrine disruption are crucial. We developed a fluorescence aptasensing platform utilizing DNase I-assisted cyclic enzymatic signal amplification in conjunction with an aptamer/graphene oxide complex. Using PEG 20000 as a surface-blocking agent, the aptasensor achieved ultralow detection limits of 2.643, 0.3039, and 0.6996 for E2, BPA, and DES, respectively. The sensor demonstrated accurate detection in plastic bottled water at spiked levels of 10 and 100 ng/mL. Systems toxicology revealed 30 potential targets for mixture-induced endocrine disruption. Molecular docking showed binding affinities of E2, BPA, and DES for ESR1 of -9.94, -8.29, and - 8.98 kcal/mol, respectively. These results highlight the effectiveness of the aptasensor and provide valuable insights into endocrine disruption mechanisms.

Ni-Pt nanozyme-mediated relaxation and colorimetric sensor for dual-modality detection of norovirus

An NiPt nanozyme-mediated relaxation and colorimetric sensor is developed for dual-modality detection of norovirus (NoV). The relaxation modality is based on the "catalase-like" activity of the NiPt nanozyme, which adjusts the hydrogen peroxide (H2O2) mediated Fe (II)/Fe(III) conversion, thereby changing the relaxation signal. Poly-γ-glutamic acid (MW ≈ 1w) can enhance the relaxivity of Fe(III) (r1 = 7.11 mM-1 s-1; r2 = 8.94 mM-1 s-1). The colorimetric modality exploits the "peroxidase-like" activity of the NiPt nanozyme, which can catalyze the oxidation of colorless 3, 3', 5, 5'-tetramethylbenzidine (TMB) to blue oxTMB in H2O2. Under optimal conditions, the relaxation modality exhibits a wide working range (1.0 × 101-1.0 × 104 fM) and a limit of detection (LOD) of 4.7 fM (equivalent to 2820 copies/μL). The spiked recoveries range from 99.593 to 106.442 %, and the relative standard deviation (RSD) is less than 5.124 %. The colorimetric modality exhibited the same working range with a lower LOD of 2.9 fM (equivalent to 1740 copies/μL) and an RSD of less than 2.611 %. Additionally, the recombinase polymerase amplification reaction enabled the detection of low NoV levels in food samples with a working range of 102-106 copies/mL and LOD of 102 copies/mL. The accuracy of the sensor in the analysis of spiked samples is consistent with the gold standard method (real-time quantitative reverse transcription-polymerase chain reaction), demonstrating the high accuracy and practical utility of the sensor.

Magnetic relaxation switch sensor based on aptamer-modified poly-L-lysine-ferroferric oxide magnetic nanoparticles and graphene oxide for the determination of insecticides in vegetables

A simple and effective graphene oxide-magnetic relaxation switch (GO-MRS) sensor that combines graphene oxide (GO) and aptamer-modified poly-L-lysine(PLL)-Fe₃O₄ nanoparticles (Fe₃O₄@PLL-Apt NPs) was designed for the detection of acetamiprid (ACE). In this sensor, Fe₃O₄@PLL-Apt NPs acted as a relaxation signal probe and GO facilitated the generation of relaxation signal changes (dispersion/aggregation shift), while the aptamer is a molecular component that recognizes ACE. This GO-assisted magnetic signal probe improves the stability of magnetic nanoparticles in solution and enhances their sensitivity to small molecules while avoiding cross-reactions. Under optimal conditions, the sensor exhibits a wide working range (10-80 nM) and low detection limit (8.43 nM). The spiked recoveries ranged from 96.54 to 103.17%, with a relative standard deviation (RSD) of less than 2.3%. In addition, the performance of the GO-MRS sensor matched that of the standard method (liquid chromatography-mass spectrometry (LC-MS)), indicating that the GO-MRS sensor is suitable for the detection of ACE in vegetables.

Cluster-bomb type magnetic biosensor for ultrasensitive detection of Vibrio parahaemolyticus based on low field nuclear magnetic resonance

Herein, a novel cluster-bomb type signal sensing and amplification strategy in low field nuclear magnetic resonance was proposed, and a magnetic biosensor for ultrasensitive homogeneous immunoassay of Vibrio parahaemolyticus (VP) was developed. The capture unit MGO@Ab was magnetic graphene oxide (MGO) immobilized by VP antibody (Ab) to capture VP. And, the signal unit PS@Gd-CQDs@Ab was polystyrene (PS) pellets covered by Ab to recognize VP and Gd-CQDs i.e. carbon quantum dots (CQDs) containing lots of magnetic signal labels Gd³⁺. In presence of VP, the immunocomplex signal unit-VP-capture unit could be formed and separated by magnetic force conveniently from the sample matrix. With the successive introduction of disulfide threitol and hydrochloric acid, signal units were cleaved and disintegrated, resulting in a homogeneous dispersion of Gd³⁺. Thus, cluster-bomb type dual signal amplification was achieved through increasing the amount and the dispersity of signal labels simultaneously. Under optimal experimental conditions, VP could be detected in the concentration range of 5-1.0 × 10⁶ CFU/mL, with a limit of quantitation (LOQ) 4 CFU/mL. In addition, satisfactory selectivity, stability and reliability could be obtained. Therefore, this cluster-bomb type signal sensing and amplification strategy is powerful in designing magnetic biosensor and detecting pathogenic bacteria.

Stimulus-Responsive DNA Hydrogel Biosensors for Food Safety Detection

Food safety has always been a major global challenge to human health and the effective detection of harmful substances in food can reduce the risk to human health. However, the food industry has been plagued by a lack of effective and sensitive safety monitoring methods due to the tension between the cost and effectiveness of monitoring. DNA-based hydrogels combine the advantages of biocompatibility, programmability, the molecular recognition of DNA molecules, and the hydrophilicity of hydrogels, making them a hotspot in the research field of new nanomaterials. The stimulus response property greatly broadens the function and application range of DNA hydrogel. In recent years, DNA hydrogels based on stimulus-responsive mechanisms have been widely applied in the field of biosensing for the detection of a variety of target substances, including various food contaminants. In this review, we describe the recent advances in the preparation of stimuli-responsive DNA hydrogels, highlighting the progress of its application in food safety detection. Finally, we also discuss the challenges and future application of stimulus-responsive DNA hydrogels.

Observation and Nursing of Adverse Reactions in Severe Patients with Enhanced MRI

In order to explore the observation and nursing of adverse reactions in severe patients with enhanced magnetic resonance imaging, a family nursing service model was proposed in patients with enhanced magnetic resonance imaging. 150 patients who underwent enhanced magnetic resonance imaging in a hospital were selected as the research objects. The patients were divided into two groups by random number table method. 75 patients in the control group received routine nursing intervention and 75 patients in the observation group received family nursing service intervention. The anxiety score, depression score, examination time, one-time success rate, comfort score, incidence of adverse reactions, excellent image quality rate and nursing satisfaction were compared between the two groups. The results showed that the anxiety score and depression score of the observation group were lower than those of the control group (P < 0.05), the examination time of the observation group was significantly shorter than that of the control group (P < 0.05), and the comfort score and one-time success rate of the observation group were significantly higher than those of the control group (P < 0.05). The incidence of adverse reactions was significantly lower than that in the control group (P < 0.05), the excellent and good image quality rate (95.00%) and nursing satisfaction (97.22%) were significantly higher than those in the control group (83.00%, 86.56%). This shows that the application effect of family nursing service mode in magnetic resonance enhanced scanning is remarkable. Therefore, the use of family care mode in MRI patient examination can effectively reduce patients' anxiety and depression scores, shorten examination time, reduce adverse reactions, improve the success rate of one-time examination, improve patients' comfort during examination and patients' evaluation of nursing services. The effect is ideal and worthy of clinical research and promotion.

Coordinated motion of molecular motors on DNA chains with branch topology

To understand the macroscopic mechanical behaviors of responsive DNA hydrogels integrated with DNA motors, we constructed a state map for the translocation process of a single FtsK_C on a single DNA chain at the molecular level and then investigated the movement of single or multiple FtsK_C motors on DNA chains with varied branch topologies. Our studies indicate that multiple FtsK_C motors can have coordinated motion, which is mainly due to the force-responsive behavior of individual FtsK_C motors. We further suggest the potential application of motors of FtsK_C, together with DNA chains of specific branch topology, to serve as strain sensors in hydrogels.

Stimuli-responsive DNA-based hydrogels for biosensing applications

The base sequences of DNA are endowed with the rich structural and functional information and are available for the precise construction of the 2D and 3D macro products. The hydrogels formed by DNA are biocompatible, stable, tunable and biologically versatile, thus, these have a wide range of promising applications in bioanalysis and biomedicine. In particular, the stimuli-responsive DNA hydrogels (smart DNA hydrogels), which exhibit a reversible and switchable hydrogel to sol transition under different triggers, have emerged as smart materials for sensing. Thus far, the combination of the stimuli-responsive DNA hydrogels and multiple sensing platforms is considered as biocompatible and is useful as the flexible recognition components. A review of the stimuli-responsive DNA hydrogels and their biosensing applications has been presented in this study. The synthesis methods to prepare the DNA hydrogels have been introduced. Subsequently, the current status of the stimuli-responsive DNA hydrogels in biosensing has been described. The analytical mechanisms are further elaborated by the combination of the stimuli-responsive DNA hydrogels with the optical, electrochemical, point-of-care testing (POCT) and other detection platforms. In addition, the prospects of the application of the stimuli-responsive DNA hydrogels in biosensing are presented.

Suspension array for multiplex immunoassay of five common endocrine disrupter chemicals

A low cost and effective indirect competitive method is reported to detect five EDCs, 17-beta-estradiol (E2), estriol (E3), bisphenol A (BPA), diethylstilbestrol (DES), and nonylphenol (NP) simultaneously, based on suspension array technology (SAT). Five kinds of complete antigens (E2-BSA, E3-BSA, BPA-BSA, DES-BPA, NP-BSA) were coupled to different encoding microspheres using purpose-made solutions in our laboratory instead of commercially available amino coupling kits; the method was further optimized for determination and reducing  the cost. Encoding and signaling fluorescence of the particles are determined at 635/532 nm emission wavelengths. High-throughput curves of five EDCs were draw and the limit of detection (LOD) were between 0.0010 ng mL^-1 ~ 0.0070 ng mL^-1. Compared with traditional ELISA methods, the SAT exhibited better specificity and sensitivity. Experiments using spiked milk and tap water samples were also carried out, and the recovery was between 85 and 110%; the results also confirmed good repeatability and reproducibility. It illustrated great potential of the present strategy in the detection of EDCs in actual samples.

Development and perspectives of rapid detection technology in food and environment

Food safety become a hot issue currently with globalization of food trade and food supply chains. Chemical pollution, microbial contamination and adulteration in food have attracted more attention worldwide. Contamination with antibiotics, estrogens and heavy metals in water environment and soil environment have also turn into an enormous threat to food safety. Traditional small-scale, long-term detection technologies have been unable to meet the current needs. In the monitoring process, rapid, convenient, accurate analysis and detection technologies have become the future development trend. We critically synthesizing the current knowledge of various rapid detection technology, and briefly touched upon the problem which still exist in research process. The review showed that the application of novel materials promotes the development of rapid detection technology, high-throughput and portability would be popular study directions in the future. Of course, the ultimate aim of the research is how to industrialization these technologies and apply to the market.