Study of the oxidation process of bismuth nanoparticles using NaClO.

Bismuth nanoparticles (NPs) colloids synthesized in deionized water by laser ablation of solids in liquids technique (LASL) were oxidized using NaClO solutions at different concentrations. Oxidized nanomaterials were characterized using several techniques. The crystalline phases of the bismuth compound were determined using Raman microspectroscopy, and the crystallographic structure was identified by x-ray diffraction (XRD). The size and morphology of the obtained nanomaterials were studied by transmission electron microscopy (TEM). The chemical states were determined using x-ray photoelectron spectroscopy (XPS), and the optical properties of the colloids were characterized by UV-vis spectroscopy. The absorption spectra were analyzed using the Tauc method to determine the band gaps of the obtained nanomaterials. Our results showed morphological changes, starting from small nanoparticles to nanosheets and a mixture of nanosheets with hollow nanoparticles. Two kinds of nanomaterials were found depending on the NaClO solution concentration: Bi2O2CO3single phase and a mixture ofδ-Bi2O3and Bi2O2CO3. Some samples were tested as photocatalysts and showed good performance in the degradation of methylene blue in solution. To the best of our knowledge, this is the first study on the oxidation process of bismuth colloidal nanoparticles at room temperature.

Bismuth subsalicylate nanoparticles with anaerobic antibacterial activity for dental applications.

In recent years, nanomaterials have been used in the medical-dental field as new alternative antimicrobial agents. Bismuth subsalicylate (BSS) has been used as an antimicrobial agent, but the effect of BSS in the form of nanoparticles (BSS-nano) as a potential antimicrobial agent has not been tested, in specific against bacteria responsible for periodontal disease. The aim of this study was to evaluate the antibacterial effect of BSS-nano against oral anaerobic bacteria and to assess the safety of BSS-nano by evaluating their cytotoxicity in human gingival fibroblast (HGF-1) cells. BSS-nano were synthesized by laser ablation and were previously physico-chemically characterized using in vitro assays. The antibacterial activity was measured using the tetrazolium-based XTT assay, and cytotoxicity was determined using lactate dehydrogenase (LDH) and MTS assays in HGF-1 cells. Transmission electron microscopy of HGF-1 exposed to BSS-nano was also performed. BSS-nano was shown to have a primary size of 4-22 nm and a polygonal shape. Among the tested bacterial strains, those with a greater sensitivity to BSS-nano (highest concentration of 21.7 µg ml-1) were A. actinomycetemcomitans, C. gingivalis, and P. gingivalis. BSS-nano at a concentration of 60 µg ml-1 showed low cytotoxicity (6%) in HFG-1 cells and was mainly localized intracellularly in acidic vesicles. Our results indicate that the concentration of BSS-nano used as an effective antibacterial agent does not induce cytotoxicity in mammalian cells; thus, BSS-nano can be applied as an antibacterial agent in dental materials or antiseptic solutions.

[HCV and HBV seropositivity in university students of the State of Nuevo Leòn, Mexico]. / Seropositividad de la infección por HCV y HBV, en Estudiantes Universitarios del Estado de Nuevo León, México.

BACKGROUND: Viral hepatitis is a contagious disease. Patients infected with hepatitis B virus (HBV) or hepatitis C virus (HCV), may be either chronically symptomatic or asymptomatic, and suffer cirrhosis and high risk of hepatic carcinoma. AIMS: Asymptomatic carriers of HBV surface antigen (HBs-Ag) or with anti-HCV antibodies are potentially infectious, and therefore a risk to public health. METHODS: This work seeks to establish the frequency of seropositivity for HBs-Ag and anti-HCV antibodies in a population of 774 newly accepted students of the Medical School of the Autonomous University of Nuevo Leon, whose average age was 18 years. Second generation ELISA test were used to screen for HBs-Ag and anti-HCV antibodies. HBs-Ag was confirmed by a neutralization test and anti-HCV antibodies were confirmed by a RIBA test. RESULTS: Three sera were positive for HBs-Ag by ELISA and only one serum (0.13% of analyzed samples) was confirmed by the neutralization technique. On the other hand 12 sera were positive for anti-HCV antibodies by ELISA, and eight of these were confirmed by RIBA (1.03% of the analyzed samples). Intensive reactivity bands were found in two sera, and weak reactivity bands were found in six sera. ELISA screening for anti-HCV antibodies showed 0.5% of false positives. CONCLUSIONS: This study shows that the frequency of anti-HCV antibodies is 7.95% times higher than that found for HBs-Ag. All seropositive patients were asymptomatic and potentially infective. This demonstrates the need to routinely screen for HBs-Ag and anti-HCV antibodies to establish the prevalence of these diseases in our area.

Seroprevalence of HTLV-I/II in blood donors in Monterrey, Mexico.

The prevalence of antibodies against human T-cell lymphotrophic virus (HTLV-I/II) in blood donors from the city of Monterrey, Mexico was investigated. We found that 4 out of 1017 sera (0.39%) reacted against HTLV-I/II, as determined by a passive agglutination test (PA). However, none of PA-positive sera reacted to HTLV-I/II specific polypeptides as demonstrated by Western blot. These findings indicate that the population of Monterrey has very low or no seroprevalence for HTLV-I/II.

[Antibodies against human T-cell lymphotropic viruses in subjects at high risk for HIV in Monterrey]. / Anticuerpos anti-virus linfotrópicos de células T humanas en sujetos de alto riesgo para la infección por VIH en Monterrey.

HIV and HTLV-1 are retrovirus that can produce human disease. It is known that HTLV-1 is associated to the adult T cell leukemia and to the spastic tropical paraparesis. AIDS is now a pandemic infection and HTLV-1 has a high endemicity in the Caribbean region and Japan, whereas the south of the United States has a low endemicity. In Mexico there is little information on HTLV-1 incidence. In the present work we looked for anti HTLV-1 antibodies in one hundred persons that belong to the high risks AIDS population in the city of Monterrey, Mexico. We found that 93 sera were positive for anti HIV antibodies in a ELISA test and seven were negative. All 93 sera were also positive in the Western Blot assay. In the confirmatory test two out of the seven negative sera were classified as indeterminate and five as negative. We also included in this study 50 sera from healthy control volunteers that did not belong to the high risk AIDS population and resulted negative in the HIV and HTLV-1 test. Anti HTLV-1 antibodies were determined by using an agglutination test with gelatin particles covered with HTLV-1 and confirmed by a Western Blot assay. We found that only three sera resulted positive in this agglutination test, but were negative by the Western Blot technique.

[Immunoelectroblotting in Mexican subjects at high risk for infection with human immunodeficiency virus (HIV)]. / La inmunoelectrotransferencia en sujetos mexicanos de alto riesgo para la infección por el virus de la inmunodeficiencia humana (VIH).

Sera from 124 persons in high risk groups were analyzed including homosexuals, blood recipients, and spouses or siblings from AIDS patients. In this study, 118 individuals had a positive ELISA for anti-HIV antibodies. Six persons had a complete immunodeficiency syndrome and a negative ELISA test. In the Western blot, 111 sera were positive, four negative, and nine scored indeterminate; four of the latter converted to positive when retested three months later. Antibodies present in the positive sera were directed against the HIV gp 41 kD in 100% of the cases and against the gp 120 kD in 82%. Frequency of recognition of p55 kD was 96% but p18 kD was only 42%.