Fentogram electrochemical detection of HIV RNA based on graphene quantum dots and gold nanoparticles.

This work reports the construction of an HIV-specific genosensor through the modification of carbon screen-printed electrodes (CSPE) with graphene quantum dots decorated with L-cysteine and gold nanoparticles (cys-GQDs/AuNps). Cys-GQDs were characterized by FT-IR and UV-vis spectra and electronic properties of the modified electrodes were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. The modification of the electrode surface with cys-GQDs and AuNps increased the electrochemical performance of the electrode, improving the electron transfer of the anionic redox probe [Fe(CN)6]3-/4- on the electrochemical platform. When compared to the bare surface, the modified electrode showed a 1.7 times increase in effective electrode area and a 29 times decrease in charge transfer resistance. The genosensor response was performed by differential pulse voltammetry, monitoring the current response of the anionic redox probe, confirmed with real genomic RNA samples, making it possible to detect 1 fg/mL. In addition, the genosensor maintained its response for 60 days at room temperature. This new genosensor platform for early detection of HIV, based on the modification of the electrode surface with cys-GQDs and AuNps, discriminates between HIV-negative and positive samples, showing a low detection limit, as well as good specificity and stability, which are relevant properties for commercial application of biosensors.

Ninhydrin as a novel DNA hybridization indicator applied to a highly reusable electrochemical genosensor for Candida auris.

This work reports a simple strategy for Candida auris genomic DNA (gDNA) detection, a multi-resistant fungus associated with nosocomial outbreaks in healthcare settings, presenting high mortality and morbidity rates. The platform was developed using gold electrode sensitized with specific DNA capture probe and ninhydrin as a novel DNA hybridization indicator. The genosensor was able to detect C. auris in urine sample by differential pulse voltammetry and electrochemical impedance spectroscopy. The biosensor's analytical performance was evaluated by differential pulse voltammetry, detecting up to 4.5 pg µL-1 of C. auris gDNA in urine (1:10, V/V). Moreover, the genosensor was reused eight times with no loss in the current signal response. The genosensor showed selectivity and stability, maintaining 100% of its response up to 80 days of storage. In order to analyze interactions of single and double-stranded DNA with ninhydrin, SEM, AFM and molecular dynamics studies followed by docking simulations were performed. Theoretical calculations showed ninhydrin interactions more favorably with dsDNA in an A-T rich binding pocket rather than with the ssDNA. Therefore, the proposed system is a promising electrochemical detection device towards a more accurate detection of C. auris gDNA in biological samples.

Application of nanomaterials for the electrical and optical detection of the hepatitis B virus.

This work describes different approaches for the detection of hepatitis B virus (HBV) genomic DNA, using electrochemical and optical techniques. The platforms consisted of a single-stranded DNA probe (HEPB1S), specific to HBV, grafted on a gold electrode modified with reduced graphene oxide or gold nanoparticles. Differential pulse voltammetry analysis indicates that the addition of HBV genomic DNA caused an increase of about 1.4 times in the current peak value, when compared to the negative control. It was observed a linear dependence with the log HBV-genomic DNA concentration and the electrochemical biosensor detected until 7.65 pg µL-1 of the target. Electrochemical impedance spectroscopy measurements showed an increase of about 2 times in the charge transfer resistance, after the addition of HBV genomic DNA. Assays using colloidal suspension of gold nanoparticles showed a shift of the peak wavelength, linearly proportional to the HBV-genomic DNA concentration, with a detection limit of 0.15 ng µL-1. The applicability of the gold nanoparticles for clinical samples was tested with success in the blood plasma. All the approaches used in this work were effective in detecting genomic DNA or blood plasma in positive samples for HBV.

Paracoccidioidomicose: correlação entre achados clínicos e laboratoriais na região de São José do Rio Preto / Paracoccidioidomycosis: correlation between clinical and laboratorial findings in São José do Rio Preto region

A paracoccidioidomicose (Pbmicose) é uma doença granulomatosa de comprometimento sistêmico causada pelo fungo dimórfico Paracoccidioides brasiliensis. As manifestações clínicas são diversas e têm relação com a resposta imune do hospedeiro. O diagnóstico de Pbmicose tem evoluído nos últimos anos devido o advento das provas sorológicas. Estas são usadas não só para diagnósticos como também para determinar a eficácia terapêutica antifúngica durante e após o tratamento. O objetivo do estudo foi correlacionar os resultados dos testes sorológicos por imunodifusão dos pacientes com pbmicose com as formas clínicas da doença na população de São José do Rio Preto. Para tanto foram utilizadas informações de 79 prontuários de pacientes atendidos no Hospital de Base da Faculdade de Medicina de São José do Rio Preto, no período de2000 a 2003. O resultado obtido mostra prevalência para população masculina, com idade entre 35 e 55 anos, sendo a maioria trabalhadora ou moradora da zona rural. Os pulmões, a mucosa oral e gânglios foram as áreas anatômicas mais comprometidas. O método diagnóstico mais utilizado foi a biópsia de lesão (70,4%), seguido de imagens radiológicas, compatíveis em 49% dos casos, e prova sorológica por imunodifusão radial positiva em 29 pacientes (40,8%). O tratamento de escolha foi a sulfadiazina, seguida pelo uso de sulfametoxazol +trimetoprim. Foi possível correlacionar os títulos de anticorpos com a forma clínica apresentada, tendo em vista a diminuição destes frente ao sucesso terapêutico.

Paracoccidioidomycosis (Pbmicosis) is a granulomatous disease with systemic impairment caused by dimorphic fungi Paracoccidioides brasiliensis. The clinical manifestations are diverse and have relation with the immune answer of the host. Paracoccidiodomycosis diagnosis has evolved in these last years due to the advent of the serologic tests. These are used not only for diagnosis, but also to determine the antifungical therapeutic effectiveness during and after the treatment. The objective of this study was to correlate the results of immunodiffusion serologic tests of patients with Paracoccidioidomycosis with the clinical forms of the disease in the population of São José do Rio Preto. Seventy nine medical records of patients assisted in the Hospital de Base of Medical School , São José do Rio Preto from 2000 to 2003 were used. The results showed that male population aged between 35 to 55 was the most significant ; the majority was workers or inhabitants from rural area. Lungs, oral mucosa and lymph nodes were the structures more frequently impaired.The biopsy of injury was the diagnostic method most used (70.4%), the radiological images were compatiblein 49% of the cases and serologic tests had been positive in 29 patients (40.8%). The chosen treatment was the sulfadiazine, followed by the administration of sulfametaxazol + trimetoprim. It was possible to correlate antibodies titers with the clinic tests; consequently the reduction of these regarding the therapeutical success.

Screening of bacterial strains for pectinolytic activity: characterization of the polygalacturonase produced by "Bacillus" sp

One hundred sixty eight bacterial strains, isolated from soil and samples of vegetable in decomposition, were screened for the use of citrus pectin as the sole carbon source. 102 were positive for pectinase depolymerization in assay plates as evidenced by clear hydrolization halos. Among them, 30(per cent) presented considerable pectinolytic activity. The cultivation of these strains by submerged and semi-solid fermentation for polygalacturose production indicated that five strains of "Bacillus" sp. produced high quantities of the enzyme. The physico-chemical characteristics, such as optimum pH of 6.0-7.0, optimum temperatures between 45ºC and 55ºC, stability at temperatures above 40ºC and in neutral and alkaline pH, were determined