Colorimetric determination of Pb2+ ions based on surface leaching of Au@Pt nanoparticles as peroxidase mimic.

We report the first use of metallic nanozyme as colorimetric probe for Pb2+ determination. The method is based on the surface leaching of Au@PtNP nanozyme by Pb2+-S2O32- ions, accompanied by a decreased catalytic activity of the metallic nanozyme. To construct this colorimetric determination, the Pt deposition onto the AuNPs was carefully investigated and other experimental factors including kind of substrate and buffer were optimized. With increasing Pb2+ concentration, the catalytic activity of the Au@PtNPs decreased gradually. As a result, the blue color at 650 nm from the oxidation of 3,3',5,5'-tetramethylbenzidine by H2O2 faded gradually. A determination limit of 3.0 nM Pb2+ with a linear range from 20 to 800 nM was obtained. The assay demonstrated negligible response to common metal ions even at elevated concentrations. This colorimetric method was applied to the determination of Pb2+ ions spiked in lake water samples, and good recoveries (96.8-105.2%) were obtained. The above results indicate the potential application of metallic nanozymes in developing robust colorimetric assays. Graphical abstract Schematic representation of the surface leaching of Au@PtNP nanozyme by Pb2+-S2O32- ions, accompanying the decreased catalytic activity of the metallic nanozyme.

Erratum: Xie, Z.-J.; Bao, X.-Y.; Peng, C.-F. Highly Sensitive and Selective Colorimetric Detection of Methylmercury Based on DNA-Functionalized Gold Nanoparticles. Sensors 2018, 18, 2679.

The authors wish to make the following corrections to their paper [...].

Highly Sensitive and Selective Colorimetric Detection of Methylmercury Based on DNA Functionalized Gold Nanoparticles.

A new colorimetric detection of methylmercury (CH3Hg⁺) was developed, which was based on the surface deposition of Hg enhancing the catalytic activity of gold nanoparticles (AuNPs). The AuNPs were functionalized with a specific DNA strand (HT7) recognizing CH3Hg⁺, which was used to capture and separate CH3Hg⁺ by centrifugation. It was found that the CH3Hg⁺ reduction resulted in the deposition of Hg onto the surface of AuNPs. As a result, the catalytic activity of the AuNPs toward the chromogenic reaction of 3,3,5,5-tetramethylbenzidine (TMB)-H2O2 was remarkably enhanced. Under optimal conditions, a limit of detection of 5.0 nM was obtained for CH3Hg⁺ with a linear range of 10⁻200 nM. We demonstrated that the colorimetric method was fairly simple with a low cost and can be conveniently applied to CH3Hg⁺ detection in environmental samples.

Engraftment of heavily transfused patients with severe aplastic anemia with a fludarabine-based regimen.

We have developed a practical conditioning regimen without anti-thymocyte globulin (ATG), irradiation, or other myeloablative alkylating agent for low-income countries in which patients with severe aplastic anemia (SAA), who usually have heavily transfused and a prolonged disease history. The application of ATG, Busulphan, and/or irradiation to cyclophosphamide (Cy) to avoid graft rejection has many short- and long-term complications. In this study, we focused on evaluating a fludarabine-based conditioning regimen, among 83 patients with SAA. Patients were treated with fludarabine (40 mg/m(2) /d; day [-5 to -2]) and cyclophosphamide (50 mg/kg/d; day [-5 to -2]). Altogether, 81 patients indicated initial engraftment, whereas two cases showed primary graft failure. And four of the 81 cases indicated graft rejection during follow-up. Regardless of a high cumulative incidence of acute (55/83; 66.2% grade II-IV; 47/83; 56.6% III-IV) and chronic graft-versus-host disease (50/83; 60.2%), in total, 77 patients showed durable engraftment and transfusion independence, and 64 are alive at a median time of 49 months with an overall survival rate of 66%. In conclusion, this conditioning indicated well toleration, mild toxicity, durable engraftment, excellent survival as well as less cost. Its application might shed new light on SAA at high risk of graft rejection in resource-limited countries.

Emulsifiers and thickeners on extrusion-cooked instant rice product.

Extrusion-cooked instant rice was prepared by optimizing the formulation with emulsifiers, glycerol monostearate (GMS), soybean lecithin (LC), and sodiumstearoyl lactylate (SSL), and thickeners, gum Arabic (GA), sodium alginate (SA), and sticky rice (SR). The emulsifiers addition caused increase of degree of gelatinization (DG), and decrease of water soluble carbohydrate (WSC), α-amylase sensitivity, water soluble index (WAI) and adhesive for extrudates, while the thickeners addition increased extrudates DG, bulk density (BD), WSC, α-amylase sensitivity, WAI, hydration rate (HR) and adhesiveness. Based on the data generated by a single additive at various levels, optimum formulation was obtained employing orthogonal matrix system with combination of the selected additives for extrusion cooking. Extrudates were evaluated for optimum hydration time followed by drying to prepare the finished product. Texture profile analysis and sensory evaluation indicate that quality of the finished product is equivalent to that of the round shaped rice and superior to a commercial instant rice product. This study also demonstrates possibility of value-added and versatile instant rice product development using broken rice.

Protective effect of isoflavones from Trifolium pratense on dopaminergic neurons.

In the present study, protective effect of five isoflavones (formononetin, daidzein, pratensein, calycosin and irilone) from Trifolium pratense on lipopolysaccharide-induced dopaminergic neurodegeneration was studied for the first time. The results showed that all five isoflavones attenuated LPS-induced decrease in dopamine uptake and the number of dopaminergic neurons in a dose-dependent manner in rat mesencephalic neuron-glia cultures. Moreover, they also significantly inhibited LPS-induced activation of microglia and production of tumor necrosis factor-alpha, nitric oxide and superoxide in mesencephalic neuron-glia cultures and microglia-enriched cultures. In addition, the rank order of protective potency of five isoflavones was: pratensein>daidzein>calycosin>formononetin>irilone. This study suggested that all five isoflavones protected dopaminergic neurons against LPS-induced injury through inhibition of microglia activation and proinflammatory factors generation.

Intraperitoneal Injection of Multiplacentas Pooled Cells Treatment on a Mouse Model with Aplastic Anemia.

Coinfusion of hematopoietic and mesenchymal stem cells is more effective than hematopoietic stem cell transplantation alone. It is necessary to explore a safe and routine mixed stem cell intraperitoneal transplantation method. Multiplacentas pooled cells were intraperitoneally injected into a radiation- and immunity-induced mouse aplastic anemia model with single time. Then, mouse survival time, peripheral blood hemoglobin count, bone marrow architecture, and donor cell engraftment were assessed. The recipient mouse exhibited donor cell engraftment in both bone marrow and peripheral blood. Survival time and peripheral blood hemoglobin count increased in placenta pooled cells treated mice, compared with model-only controls (P = 0.048 and P = 0.000, resp.). However, placentas pooled cells failed to cause a significant decrease in bone marrow pimelosis area (P = 0.357). Intraperitoneally transplanted multiplacentas pooled cells can survive and engraft into a host body through blood circulation, which can increase the life span of an aplastic anemia model mice, and delay but not abrogate the development of aplastic anemia. Furthermore, they appear to play a role in increasing peripheral blood hemoglobin level response for increasing the life span of aplastic anemia model mice.

[Recombinant adeno-associated virus 2-mediated green fluorescent protein expression in bone marrow mesenchymal stem cells derived from acute myelogenous leukemia patients].

OBJECTIVE: To explore the possibility of using autologous bone marrow mesenchymal stem cells (BMSC) as a vehicle to deliver recombinant adeno-associated virus 2-mediated enhanced green fluorescent protein (rAAV-2-eGFP) in vitro, therefore to find an alternative solution for gene therapy of hematological malignancy. METHODS: BMSCs isolated from the bone marrow of patients with acute myelogenous leukemia (AML) at the onset of disease were infected by rAAV-2-eGFP at different multiplicity of infection (MOI=10(2), 10(3), 10(4), 10(5), 10(6), and 10(7), respectively). Phase-contrast fluorescent microscope and flow cytometry were employed to evaluate the expression of enhanced green fluorescent protein (eGFP). RESULTS: Ten to fourteen days after the transfection, eGFP expression began to be detected and the transfection efficiency ranged between 0.3% to 2%, which failed to be increased with the increase of MOI. The transduced eGFP could maintain a long-term stable expression in vitro in the 61 days of observation, and from 12 to 33 days after transfection, eGFP percentage underwent a decrease from the initial 1.16% to 0.5%-0.6% and maintained this expression level till 61 days after transfection. CONCLUSION: rAAV can be used with BMSCs for in vitro gene therapy, but the poor transfection efficiency of these cells remains a significant obstacle for its further application.

[HLA haploidentical peripheral blood stem cells transplantation for ß thalassemia major].

OBJECTIVE: To evaluate the feasibility of HLA haploidentical peripheral blood hematopoietic stem cell transplantation (PBSCT) for patients with ß thalassemia major. METHODS: Sixteen patients with ß thalassemia major received HLA haploidentical PBSCT from parents. Two conditioning regimens were used. Regimen A was adopted before December 2007, which consisted of fludarabine (total 150 mg/m²), busulfex (total 520 mg/m²), cyclophosphamide (CTX, total 100 mg/kg), antithymocyte globulin (ATG, total 10 mg/kg) and total body irradiation of 3 Gy. Regimen B was adopted after December 2007, which consisted of fludarabine (total 240 mg/m²), busulfex (total 520 mg/m²), CTX (total 100 mg/kg), and ATG (total 10 mg/kg). Combination of cyclosporin (CsA), methotrexate (MTX) and mycophenolate mofetil (MMF) were used for prophylaxis of graft-versus-host disease (GVHD). RESULTS: Of 16 patients, 14 (87.5%) had sustained engraftment. The median days of neutrophil exceeding 0.5 × 109/L and platelet exceeding 20 × 109/L were 13 days (range 10 - 17 days) and 15 days (range 14 - 20 days) after PBSCT, respectively. Complete chimerism was achieved in all the 14 patients at one month after PBSCT. One patient lost his graft with autologous reconstitution 52 days after transplantation. Four patients had grade II-IV acute GVHD and one patient had chronic extensive GVHD. In the 49-month median follow-up duration, 13 of 16 patients were alive in disease-free situation. CONCLUSION: HLA haploidentical PBSCT, which could provide stable and sustained engraftment for thalassemia major patients with no HLA identical donor, is a promising treatment strategy.

[Are leukemic patient bone marrow mesenchymal stem cells malignant?].

The study was aimed to explore whether there are leukemic characteristics in the bone marrow mesenchymal stem cells (BMMSC) from leukemic patients as compared with normal controls. The mesenchymal stem cells from bone marrow of normal volunteers and patients with APL and CML were isolated, then cultured and proliferated in vitro. The morphology, growth curve and cell surface markers of two different sources mesenchymal stem cells were investigated for detecting whether the bone marrow mesenchymal stem cells derived from leukemia patients have the specific abnormal fusion gene of leukemia cells through fluorescent in situ hybridization. The results indicated that there was no significant difference between the mesenchymal stem cells derived from different subjects, the bone marrow mesenchymal stem cells derived from leukemia patients did not have the clonal malignant fusion gene as seen in the leukemia cells. Taken altogether, mesenchymal stem cells derived from leukemia patients had no biological differences as compared with those from normal volunteers, and no malignant clonal abnormality was found. It is concluded that mesenchymal stem cells derived from leukemia patients as an alternative vehicle may be used for assistant of autologous hematopoietic stem cell transplantation or cell therapy and gene therapy.