Effective Electrochemiluminescence Aptasensor for Detection of Atrazine Residue.

According to the chemiluminescence characteristics of the luminol-hydrogen peroxide (H2O2) system, this work designed a novel and effective electrochemiluminescence (ECL) aptasensor to detect atrazine (ATZ) rapidly. Silver nanoparticles (AgNPs) could effectively catalyze the decomposition of H2O2 and enhance the ECL intensity of the luminol-H2O2 system. Once ATZ was modified on the aptasensor, the ECL intensity was significantly weakened because of the specific combination between ATZ and its aptamer. Therefore, the changes in ECL intensity could be used to detect the concentration of ATZ. Under optimal detecting conditions, the aptasensor had a wide linear range from 1 × 10-3 ng/mL to 1 × 103 ng/mL and a low limit of detection (3.3 × 10-4 ng/mL). The designed aptasensor had the advantages of good stability, reproducibility, and specificity. The aptasensor could be used to detect the ATZ content of tap water, soil, and cabbage and had satisfactory results. This work effectively constructs a novel, effective, and rapid ECL aptasensor for detecting ATZ in actual samples.

Fluorescence Assay for Detecting Four Organophosphorus Pesticides Using Fluorescently Labeled Aptamer.

In this work, we reported a rapid and sensitive fluorescence assay in homogenous solution for detecting organophosphorus pesticides by using tetramethylrhodamine (TAMRA)-labeled aptamer and its complementary DNA (cDNA) with extended guanine (G) bases. The hybridization of cDNA and aptamer drew TAMRA close to repeated G bases, then the fluorescence of TAMRA was quenched by G bases due to the photoinduced electron transfer (PET). Upon introducing the pesticide target, the aptamer bound to pesticide instead of cDNA because of the competition between pesticide and cDNA. Thus, the TAMRA departed from G bases, resulting in fluorescence recovery of TAMRA. Under optimal conditions, the limits of detection for phorate, profenofos, isocarbophos, and omethoate were 0.333, 0.167, 0.267, and 0.333 µg/L, respectively. The method was also used in the analysis of profenofos in vegetables. Our fluorescence design was simple, rapid, and highly sensitive, which provided a means for monitoring the safety of agricultural products.

Nanoporous Graphene Oxide-Based Quartz Crystal Microbalance Gas Sensor with Dual-Signal Responses for Trimethylamine Detection.

This paper presents a straightforward method to develop a nanoporous graphene oxide (NGO)-functionalized quartz crystal microbalance (QCM) gas sensor for the detection of trimethylamine (TMA), aiming to form a reliable monitoring mechanism strategy for low-concentration TMA that can still cause serious odor nuisance. The synthesized NGO material was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy to verify its structure and morphology. Compared with the bare and GO-based QCM sensors, the NGO-based QCM sensor exhibited ultra-high sensitivity (65.23 Hz/µL), excellent linearity (R2 = 0.98), high response/recovery capability (3 s/20 s) and excellent repeatability (RSD = 0.02, n = 3) toward TMA with frequency shift and resistance. Furthermore, the selectivity of the proposed NGO-based sensor to TMA was verified by analysis of the dual-signal responses. It is also proved that increasing the conductivity did not improve the resistance signal. This work confirms that the proposed NGO-based sensor with dual signals provides a new avenue for TMA sensing, and the sensor is expected to become a potential candidate for gas detection.

The effect of planned active play on the fundamental movement skills of preschool children.

BACKGROUND: At present, Chinese children aged 3-6 years old are facing challenges such as insufficient physical activity, declining physical health, and obesity, and China has yet to issue curriculum standards or physical activity guidelines for this age group. At the same time, the present kindergarten physical activity curriculum is insufficient. To address this issue, this study focused on designing and executing a planned active play intervention program for the kindergarten setting to analyze its efficacy in enhancing children's fundamental movement skills (FMS). This study aims to provide a reference for the theoretical and practical exploration of children's acquisition of fundamental movement skills in the Chinese context. METHODS: Fifty-two preschoolers participated in this study and were either part of an intervention group (n = 30) or a control group (n = 24). Children's FMS were assessed before and after the intervention using the Test of Gross Motor Development-3 (TGMD-3) and the balance ability of the The Movement Assessment Battery for Children-2 (MABC-2). Physical activity (PA) during the planned active play intervention and the routine physical activity curriculum were assessed using the SOFIT throughout the intervention. RESULTS: All the children significantly improved their locomotor skills, ball skills, and TGMD from baseline to the late assessment (p < 0.05). Children in the planned active play intervention group demonstrated greater rates of change (p < 0.001) and scored higher on ball skills and TGMD in the late assessment than those in the control group (p < 0.001). The children in the intervention group, but not those in the control group, significantly improved their balance over time (p < 0.05), and the former had greater rates of change (p < 0.001). Similarly, planned active play was found to provide children with more physical activity than the routine physical activity curriculum. CONCLUSIONS: The eight-week planned active play intervention was effective in improving FMS in preschool children, with higher rates of FMS change in children who completed the intervention than children in the control group.

Screening of broad-spectrum aptamer and development of electrochemical aptasensor for simultaneous detection of penicillin antibiotics in milk.

Penicillin antibiotics (PENs) play an important role in killing pathogenic bacteria. However, the residues of various penicillin antibiotics in milk gradually accumulate in the human body with the increase of milk intake, which causes direct harm to the human body. Aptamers can be used as recognition element of sensors. It is great significance to use broad-spectrum aptamers for simultaneous detection of PENs. In this study, we reported the screening and identification of DNA aptamers for PENs. The aptamers were screened by graphene oxide-systematic evolution of ligands by exponential enrichment (GO-SELEX). The broad-spectrum aptamers with high affinity and specificity were successfully obtained after 13 rounds of screening. The affinity and specificity of candidate aptamers were analyzed by a GO fluorescence competition method. Further sequence analysis revealed that a truncated 47 nt aptamer (P-11-1) had a higher affinity than the original 79 nt aptamer. The truncated aptamer P-11-1 was used as a recognition element, and an electrochemical aptasensor was prepared using gold nanoparticles (AuNPs) combined with ferroferric oxide-multi walled carbon nanotube (Fe3O4-MWCNTs) complex. The results showed that the developed aptasensor achieved the simultaneous detection of PENs in milk samples across a concentration range of 2 nM-10,000 nM, achieving a limit of detection of 0.667 nM. This methodology provided a simple and sensitive new thinking for antibiotic multi-residue detection.

Novel Electrochemical Aptasensor Based on Ordered Mesoporous Carbon/2D Ti3C2 MXene as Nanocarrier for Simultaneous Detection of Aminoglycoside Antibiotics in Milk.

Herein, a novel electrochemical aptasensor using a broad-spectrum aptamer as a biorecognition element was constructed based on a screen-printed carbon electrode (SPCE) for simultaneous detection of aminoglycoside antibiotics (AAs). The ordered mesoporous carbon (OMC) was firstly modified on 2D Ti3C2 MXene. The addition of OMC not only effectively improved the stability of the aptasensor, but also prevented the stacking of Ti3C2 sheets, which formed a good current passage for signal amplification. The prepared OMC@Ti3C2 MXene functioned as a nanocarrier to accommodate considerable aptamers. In the presence of AAs, the transport of electron charge on SPCE surface was influenced by the bio-chemical reactions of the aptamer and AAs, generating a significant decline in the differential pulse voltammetry (DPV) signals. The proposed aptasensor presented a wide linear range and the detection limit was 3.51 nM. Moreover, the aptasensor, with satisfactory stability, reproducibility and specificity, was successfully employed to detect the multi-residuals of AAs in milk. This work provided a novel strategy for monitoring AAs in milk.