Here, we firstly report a wireless magnetoelastic (ME) nanobiosensor, based on ME materials and gold nanoparticles (AuNPs), for highly sensitive detection of atrazine employing the competitive immunoassay. In response to a time-varying magnetic field, the ME material longitudinally vibrates at its resonance frequency which can be affected by its mass loading. The layer of AuNPs coating on the ME material contributes to its biocompatibility, stability, and sensitivity. The atrazine antibody was oriented immobilized on the AuNPs-coated ME material surface through protein A, improving the nanobiosensor's performance. Atomic force microscope (AFM) analysis proved that the immobilization of atrazine antibody was successful. Furthermore, to enhance the sensitivity, atrazine–albumin conjugate (Atr–BSA) was induced to compete with atrazine for binding with atrazine antibody, amplifying the signal response. The resonance frequency shift is inversely and linearly proportional to the logarithm of atrazine concentrations ranging from 1 ng/mL to 100 μg/mL, with the sensitivity of 3.43 Hz/μg mL−1 and the detection limit of 1 ng/mL, which is significantly lower than the standard established by US Environmental Protection Agency (EPA). The experimental results indicated that the ME nanobiosensor displayed strong specificity and stability toward atrazine. This study provides a new convenient method for rapid, selective, and highly sensitive detection of atrazine, which has implications for its applications in water quality monitoring and other environmental detection fields.
Abstract Background Chikungunya virus (CHIKV) and Dengue virus (DENV) have similar clinical symptoms, which often induce misdiagnoses. Therefore, an antigen detection diagnostic system that can clearly identify these two viruses is desirable. Methods In this study, we developed a novel peptide with high affinity and specificity to CHIKV, and further constructed peptide aptamer-based TRFIA assay to efficiently detect CHIKV. Peptide aptamer B2 (ITPQSSTTEAEL) and B3 (DTQGSNWI) were obtained through computer-aided design and selected as CHIKV-specific peptide aptamers based on their high binding affinity, strong hydrogen bonding, and RMSD of molecular docking. Then, a sandwich-Time-Resolved Fluoroimmunoassay (TRFIA) was successfully constructed for the detection of the interaction between peptide aptamers and viruses. Results When using B2 as the detection element, highly specific detection of CHIKV E2 was achieved with detection limits of 8.5 ng/ml in PBS solution. Variation coefficient between inter-assay showed the disturbances received from the detection of clinical fluid specimens (including serum and urine), were also within acceptable limits. The detection limits for 10-fold dilution serum and urine were 57.8 ng/mL and 147.3 ng/mL, respectively. The fluorescent signal intensity exhibited a good linear correlation with E2 protein concentration in the range of 0-1000 ng/mL, indicating the potential for quantitative detection of E2 protein. Conclusions These results demonstrate that the construction of peptide aptamers with high affinity and specificity provides an excellent method for rapid diagnostic element screening, and the developed peptide aptamer B2 contributed to better detection of CHIKV viral particles compared to traditional antibodies.
A simple and inexpensive method to synthesize ZnO nanograin powders from Zn powders is reported in this paper and phase change from Zn powders to ZnO nanograins during the process is studied in detail. Zinc powders were immersed into 1.0 mol/l oxalic acid aqueous solution for various times and then dried at ambient condition. As-prepared precursors were decomposed in air at temperatures of 200-600 degrees C for 2 hours. As-prepared samples were characterized with scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The results show that the precursors after immersing zinc powders in oxalic acid aqueous solution are ZnC2O4 x 2H2O/Zn(OH)2 dense blocks which consist of 5-10 nm grains. ZnC2O4 x 2H2O/Zn(OH)2 dense blocks decompose into ZnC2O4/ZnO blocks after heating in air at 200 degrees C x ZnC2O4/ZnO blocks further decompose into loose ZnO blocks after heating in air at 400 degrees C and grain sizes of ZnO are - 10 nm in the loose blocks. The phase transitions from Zn powders to ZnO nanograins during the two-step synthesis are analyzed thermodynamically. A physical model is suggested to explain the morphology changes from ZnC2O4 x 2H2O/Zn(OH)2 dense blocks to ZnO loose blocks, based on the volume changes during the phase transitions.
The purpose of this study was to assess the efficacy and toxicity of HAI regimen [(homoharringtonine 2.5 mg/(m(2)×d), days 1 - 7; cytarabine 150 mg/(m(2)×d), days 1 - 7; idarubicin 9 mg/(m(2)×d), days 1 - 7)] for induction treatment of newly diagnosed acute myeloid leukemia (AML) (except acute promyelocytic leukemia). 31 patients with newly diagnosed AML, aged 39 (14 - 58) years, were enrolled in this clinical study. The complete remission (CR) rate, especially after one course, the overall survival (OS) rate and relapse free survival (RFS) rate were estimated. The outcomes were compared between different prognostic groups according to World Health Organization (WHO) classification, genetics and initial WBC count. Safety was evaluated using standard WHO criteria. The results showed that 26 patients (84%) achieved CR after 1 course of induction. The CR rate for the patients with favorable, intermediate and unfavorable cytogenetics was 90%, 88% and 60% respectively. All 7 patients with a high initial WBC count (≥ 100×10(9)/L) obtained CR, while 19 out of 24 without a high initial WBC count obtained CR. With a median follow-up of 15(range 2-56) months, the estimated 3-year OS rate for all patients and the patients with CR was 44% and 52% respectively. The 3-year RFS rate was 51%. The patients receiving induction chemotherapy died of the chemotherapy. Profound myelosuppression was seen in all patients after the HAI induction with the median duration of neutropenia (ANC < 0.2×10(9)/L) of 16 (6 - 24) days. As the most common toxicity, severe infections (grade III-IV) involved in all the patients and the duration of febris was 6 (1 - 36) days. The incidence of septemia and invasive fungus infection were 19.4% and 45.2% respectively. The incidence of non-infection fever, increased glutamic-pyruvic transaminase (GPT), diarrhea, increased bilirubin and oral cavity mucositis were 6.5%, 6.5%, 3.2%, 3.2%, 3.2% respectively, as the more frequent severe non-hematological toxicities. It is concluded that HAI regimen is a high efficient induction schedule for the newly diagnosed AML, and archive the higher CR rate after one course than DNR/Ara-C standard induction regimen. Side effects are acceptable, except severe infection.
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